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Date: Tue, 17 Apr 2018 14:47:01 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: perf probe line numbers + CONFIG_DEBUG_INFO_SPLIT=y
Hi Masami,
I just tried building the kernel using:
CONFIG_DEBUG_INFO=y
# CONFIG_DEBUG_INFO_REDUCED is not set
CONFIG_DEBUG_INFO_SPLIT=y
# CONFIG_DEBUG_INFO_DWARF4 is not set
that info split looked interesting, and I thought that since we
use elfutils we'd get that for free somehow, so I tried getname_flags
and got the output at the end of this message, with these artifacts:
1) the function signature doesn't appear at the start of the '-L
getname_flags' output
2) offsets are not calculated, just the line numbers in fs/namei.c (it
matches the first line :130 with the first line number.
And then if I try adding a probe at some places, say line 202, to
collect the filename being brought from userspace to the kernel, it
fails:
[root@...et perf]# perf probe "vfs_getname=getname_flags:202 pathname=result->name:string"
Probe point 'getname_flags:202' not found.
Error: Failed to add events.
[root@...et perf]#
If I just try putting the probe without renaming nor collecting vars, to
have a simpler probe request:
[root@...et perf]# perf probe getname_flags:202
Probe point 'getname_flags:202' not found.
Error: Failed to add events.
[root@...et perf]#
Or even:
[root@...et perf]# perf probe getname_flags
Failed to find scope of probe point.
getname_flags is out of .text, skip it.
Error: Failed to add events.
[root@...et perf]#
[root@...et perf]# grep getname_flags /proc/kallsyms
ffffffffb329a5a0 T getname_flags
[root@...et perf]#
I'll try with CONFIG_DEBUG_INFO_SPLIT not set, but have you ever got
such a report?
- Arnaldo
# perf probe -L getname_flags
</home/acme/git/linux/fs/namei.c:130>
130 {
struct filename *result;
char *kname;
int len;
BUILD_BUG_ON(offsetof(struct filename, iname) % sizeof(long) != 0);
result = audit_reusename(filename);
137 if (result)
return result;
140 result = __getname();
141 if (unlikely(!result))
142 return ERR_PTR(-ENOMEM);
/*
* First, try to embed the struct filename inside the names_cache
* allocation
*/
148 kname = (char *)result->iname;
149 result->name = kname;
151 len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX);
152 if (unlikely(len < 0)) {
153 __putname(result);
154 return ERR_PTR(len);
}
/*
* Uh-oh. We have a name that's approaching PATH_MAX. Allocate a
* separate struct filename so we can dedicate the entire
* names_cache allocation for the pathname, and re-do the copy from
* userland.
*/
163 if (unlikely(len == EMBEDDED_NAME_MAX)) {
const size_t size = offsetof(struct filename, iname[1]);
kname = (char *)result;
/*
* size is chosen that way we to guarantee that
* result->iname[0] is within the same object and that
* kname can't be equal to result->iname, no matter what.
*/
result = kzalloc(size, GFP_KERNEL);
173 if (unlikely(!result)) {
174 __putname(kname);
175 return ERR_PTR(-ENOMEM);
}
177 result->name = kname;
178 len = strncpy_from_user(kname, filename, PATH_MAX);
179 if (unlikely(len < 0)) {
180 __putname(kname);
181 kfree(result);
182 return ERR_PTR(len);
}
184 if (unlikely(len == PATH_MAX)) {
185 __putname(kname);
186 kfree(result);
187 return ERR_PTR(-ENAMETOOLONG);
}
}
191 result->refcnt = 1;
/* The empty path is special. */
193 if (unlikely(!len)) {
194 if (empty)
195 *empty = 1;
196 if (!(flags & LOOKUP_EMPTY)) {
197 putname(result);
198 return ERR_PTR(-ENOENT);
}
}
202 result->uptr = filename;
203 result->aname = NULL;
audit_getname(result);
return result;
206 }
struct filename *
getname(const char __user * filename)
210 {
211 return getname_flags(filename, 0, NULL);
}
struct filename *
getname_kernel(const char * filename)
216 {
struct filename *result;
218 int len = strlen(filename) + 1;
220 result = __getname();
221 if (unlikely(!result))
222 return ERR_PTR(-ENOMEM);
224 if (len <= EMBEDDED_NAME_MAX) {
225 result->name = (char *)result->iname;
226 } else if (len <= PATH_MAX) {
const size_t size = offsetof(struct filename, iname[1]);
struct filename *tmp;
tmp = kmalloc(size, GFP_KERNEL);
231 if (unlikely(!tmp)) {
232 __putname(result);
233 return ERR_PTR(-ENOMEM);
}
235 tmp->name = (char *)result;
result = tmp;
} else {
238 __putname(result);
239 return ERR_PTR(-ENAMETOOLONG);
}
241 memcpy((char *)result->name, filename, len);
242 result->uptr = NULL;
243 result->aname = NULL;
244 result->refcnt = 1;
audit_getname(result);
return result;
248 }
void putname(struct filename *name)
251 {
252 BUG_ON(name->refcnt <= 0);
254 if (--name->refcnt > 0)
return;
257 if (name->name != name->iname) {
258 __putname(name->name);
259 kfree(name);
} else
261 __putname(name);
262 }
static int check_acl(struct inode *inode, int mask)
{
#ifdef CONFIG_FS_POSIX_ACL
struct posix_acl *acl;
269 if (mask & MAY_NOT_BLOCK) {
270 acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS);
271 if (!acl)
return -EAGAIN;
/* no ->get_acl() calls in RCU mode... */
274 if (is_uncached_acl(acl))
275 return -ECHILD;
276 return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK);
}
279 acl = get_acl(inode, ACL_TYPE_ACCESS);
280 if (IS_ERR(acl))
return PTR_ERR(acl);
282 if (acl) {
283 int error = posix_acl_permission(inode, acl, mask);
posix_acl_release(acl);
return error;
}
#endif
return -EAGAIN;
}
/*
* This does the basic permission checking
*/
static int acl_permission_check(struct inode *inode, int mask)
{
297 unsigned int mode = inode->i_mode;
299 if (likely(uid_eq(current_fsuid(), inode->i_uid)))
300 mode >>= 6;
else {
302 if (IS_POSIXACL(inode) && (mode & S_IRWXG)) {
int error = check_acl(inode, mask);
304 if (error != -EAGAIN)
return error;
}
308 if (in_group_p(inode->i_gid))
309 mode >>= 3;
}
/*
* If the DACs are ok we don't need any capability check.
*/
315 if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0)
316 return 0;
return -EACCES;
}
/**
* generic_permission - check for access rights on a Posix-like filesystem
* @inode: inode to check access rights for
* @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...)
*
* Used to check for read/write/execute permissions on a file.
* We use "fsuid" for this, letting us set arbitrary permissions
* for filesystem access without changing the "normal" uids which
* are used for other things.
*
* generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
* request cannot be satisfied (eg. requires blocking or too much complexity).
* It would then be called again in ref-walk mode.
*/
int generic_permission(struct inode *inode, int mask)
335 {
int ret;
/*
* Do the basic permission checks.
*/
ret = acl_permission_check(inode, mask);
342 if (ret != -EACCES)
return ret;
345 if (S_ISDIR(inode->i_mode)) {
/* DACs are overridable for directories */
347 if (!(mask & MAY_WRITE))
348 if (capable_wrt_inode_uidgid(inode,
CAP_DAC_READ_SEARCH))
return 0;
if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE))
return 0;
353 return -EACCES;
}
/*
* Searching includes executable on directories, else just read.
*/
359 mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
360 if (mask == MAY_READ)
361 if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH))
return 0;
/*
* Read/write DACs are always overridable.
* Executable DACs are overridable when there is
* at least one exec bit set.
*/
368 if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO))
369 if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE))
return 0;
return -EACCES;
373 }
EXPORT_SYMBOL(generic_permission);
/*
* We _really_ want to just do "generic_permission()" without
* even looking at the inode->i_op values. So we keep a cache
* flag in inode->i_opflags, that says "this has not special
* permission function, use the fast case".
*/
static inline int do_inode_permission(struct inode *inode, int mask)
{
384 if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) {
385 if (likely(inode->i_op->permission))
386 return inode->i_op->permission(inode, mask);
/* This gets set once for the inode lifetime */
spin_lock(&inode->i_lock);
390 inode->i_opflags |= IOP_FASTPERM;
spin_unlock(&inode->i_lock);
}
393 return generic_permission(inode, mask);
}
/**
* sb_permission - Check superblock-level permissions
* @sb: Superblock of inode to check permission on
* @inode: Inode to check permission on
* @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
*
* Separate out file-system wide checks from inode-specific permission checks.
*/
static int sb_permission(struct super_block *sb, struct inode *inode, int mask)
{
406 if (unlikely(mask & MAY_WRITE)) {
407 umode_t mode = inode->i_mode;
/* Nobody gets write access to a read-only fs. */
410 if (sb_rdonly(sb) && (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
return -EROFS;
}
return 0;
}
/**
* inode_permission - Check for access rights to a given inode
* @inode: Inode to check permission on
* @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
*
* Check for read/write/execute permissions on an inode. We use fs[ug]id for
* this, letting us set arbitrary permissions for filesystem access without
* changing the "normal" UIDs which are used for other things.
*
* When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
*/
int inode_permission(struct inode *inode, int mask)
428 {
int retval;
retval = sb_permission(inode->i_sb, inode, mask);
if (retval)
return retval;
if (unlikely(mask & MAY_WRITE)) {
/*
* Nobody gets write access to an immutable file.
*/
439 if (IS_IMMUTABLE(inode))
440 return -EPERM;
/*
* Updating mtime will likely cause i_uid and i_gid to be
* written back improperly if their true value is unknown
* to the vfs.
*/
if (HAS_UNMAPPED_ID(inode))
448 return -EACCES;
}
retval = do_inode_permission(inode, mask);
452 if (retval)
return retval;
455 retval = devcgroup_inode_permission(inode, mask);
456 if (retval)
return retval;
459 return security_inode_permission(inode, mask);
460 }
EXPORT_SYMBOL(inode_permission);
/**
* path_get - get a reference to a path
* @path: path to get the reference to
*
* Given a path increment the reference count to the dentry and the vfsmount.
*/
void path_get(const struct path *path)
470 {
471 mntget(path->mnt);
472 dget(path->dentry);
473 }
EXPORT_SYMBOL(path_get);
/**
* path_put - put a reference to a path
* @path: path to put the reference to
*
* Given a path decrement the reference count to the dentry and the vfsmount.
*/
void path_put(const struct path *path)
483 {
484 dput(path->dentry);
485 mntput(path->mnt);
486 }
EXPORT_SYMBOL(path_put);
#define EMBEDDED_LEVELS 2
struct nameidata {
struct path path;
struct qstr last;
struct path root;
struct inode *inode; /* path.dentry.d_inode */
unsigned int flags;
unsigned seq, m_seq;
int last_type;
unsigned depth;
int total_link_count;
struct saved {
struct path link;
struct delayed_call done;
const char *name;
unsigned seq;
} *stack, internal[EMBEDDED_LEVELS];
struct filename *name;
struct nameidata *saved;
struct inode *link_inode;
unsigned root_seq;
int dfd;
} __randomize_layout;
static void set_nameidata(struct nameidata *p, int dfd, struct filename *name)
{
515 struct nameidata *old = current->nameidata;
516 p->stack = p->internal;
517 p->dfd = dfd;
518 p->name = name;
519 p->total_link_count = old ? old->total_link_count : 0;
520 p->saved = old;
521 current->nameidata = p;
}
static void restore_nameidata(void)
525 {
526 struct nameidata *now = current->nameidata, *old = now->saved;
528 current->nameidata = old;
529 if (old)
530 old->total_link_count = now->total_link_count;
531 if (now->stack != now->internal)
532 kfree(now->stack);
533 }
static int __nd_alloc_stack(struct nameidata *nd)
536 {
struct saved *p;
539 if (nd->flags & LOOKUP_RCU) {
p= kmalloc(MAXSYMLINKS * sizeof(struct saved),
GFP_ATOMIC);
542 if (unlikely(!p))
543 return -ECHILD;
} else {
p= kmalloc(MAXSYMLINKS * sizeof(struct saved),
GFP_KERNEL);
547 if (unlikely(!p))
548 return -ENOMEM;
}
550 memcpy(p, nd->internal, sizeof(nd->internal));
551 nd->stack = p;
552 return 0;
553 }
/**
* path_connected - Verify that a path->dentry is below path->mnt.mnt_root
* @path: nameidate to verify
*
* Rename can sometimes move a file or directory outside of a bind
* mount, path_connected allows those cases to be detected.
*/
static bool path_connected(const struct path *path)
563 {
564 struct vfsmount *mnt = path->mnt;
565 struct super_block *sb = mnt->mnt_sb;
/* Bind mounts and multi-root filesystems can have disconnected paths */
568 if (!(sb->s_iflags & SB_I_MULTIROOT) && (mnt->mnt_root == sb->s_root))
return true;
571 return is_subdir(path->dentry, mnt->mnt_root);
572 }
static inline int nd_alloc_stack(struct nameidata *nd)
{
576 if (likely(nd->depth != EMBEDDED_LEVELS))
return 0;
578 if (likely(nd->stack != nd->internal))
return 0;
580 return __nd_alloc_stack(nd);
}
static void drop_links(struct nameidata *nd)
{
585 int i = nd->depth;
586 while (i--) {
587 struct saved *last = nd->stack + i;
do_delayed_call(&last->done);
clear_delayed_call(&last->done);
}
}
static void terminate_walk(struct nameidata *nd)
594 {
drop_links(nd);
596 if (!(nd->flags & LOOKUP_RCU)) {
int i;
path_put(&nd->path);
599 for (i = 0; i < nd->depth; i++)
600 path_put(&nd->stack[i].link);
601 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
path_put(&nd->root);
603 nd->root.mnt = NULL;
}
} else {
606 nd->flags &= ~LOOKUP_RCU;
607 if (!(nd->flags & LOOKUP_ROOT))
608 nd->root.mnt = NULL;
rcu_read_unlock();
}
611 nd->depth = 0;
612 }
/* path_put is needed afterwards regardless of success or failure */
615 static bool legitimize_path(struct nameidata *nd,
struct path *path, unsigned seq)
{
618 int res = __legitimize_mnt(path->mnt, nd->m_seq);
619 if (unlikely(res)) {
620 if (res > 0)
621 path->mnt = NULL;
622 path->dentry = NULL;
623 return false;
}
625 if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) {
path->dentry = NULL;
return false;
}
629 return !read_seqcount_retry(&path->dentry->d_seq, seq);
630 }
static bool legitimize_links(struct nameidata *nd)
633 {
int i;
635 for (i = 0; i < nd->depth; i++) {
636 struct saved *last = nd->stack + i;
637 if (unlikely(!legitimize_path(nd, &last->link, last->seq))) {
drop_links(nd);
639 nd->depth = i + 1;
640 return false;
}
}
643 return true;
644 }
/*
* Path walking has 2 modes, rcu-walk and ref-walk (see
* Documentation/filesystems/path-lookup.txt). In situations when we can't
* continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
* normal reference counts on dentries and vfsmounts to transition to ref-walk
* mode. Refcounts are grabbed at the last known good point before rcu-walk
* got stuck, so ref-walk may continue from there. If this is not successful
* (eg. a seqcount has changed), then failure is returned and it's up to caller
* to restart the path walk from the beginning in ref-walk mode.
*/
/**
* unlazy_walk - try to switch to ref-walk mode.
* @nd: nameidata pathwalk data
* Returns: 0 on success, -ECHILD on failure
*
* unlazy_walk attempts to legitimize the current nd->path and nd->root
* for ref-walk mode.
* Must be called from rcu-walk context.
* Nothing should touch nameidata between unlazy_walk() failure and
* terminate_walk().
*/
static int unlazy_walk(struct nameidata *nd)
669 {
670 struct dentry *parent = nd->path.dentry;
672 BUG_ON(!(nd->flags & LOOKUP_RCU));
674 nd->flags &= ~LOOKUP_RCU;
675 if (unlikely(!legitimize_links(nd)))
goto out2;
677 if (unlikely(!legitimize_path(nd, &nd->path, nd->seq)))
goto out1;
679 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
680 if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq)))
goto out;
}
rcu_read_unlock();
684 BUG_ON(nd->inode != parent->d_inode);
685 return 0;
out2:
688 nd->path.mnt = NULL;
689 nd->path.dentry = NULL;
out1:
691 if (!(nd->flags & LOOKUP_ROOT))
692 nd->root.mnt = NULL;
out:
rcu_read_unlock();
695 return -ECHILD;
696 }
/**
* unlazy_child - try to switch to ref-walk mode.
* @nd: nameidata pathwalk data
* @dentry: child of nd->path.dentry
* @seq: seq number to check dentry against
* Returns: 0 on success, -ECHILD on failure
*
* unlazy_child attempts to legitimize the current nd->path, nd->root and dentry
* for ref-walk mode. @dentry must be a path found by a do_lookup call on
* @nd. Must be called from rcu-walk context.
* Nothing should touch nameidata between unlazy_child() failure and
* terminate_walk().
*/
static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq)
{
713 BUG_ON(!(nd->flags & LOOKUP_RCU));
715 nd->flags &= ~LOOKUP_RCU;
716 if (unlikely(!legitimize_links(nd)))
goto out2;
718 if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq)))
goto out2;
720 if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref)))
goto out1;
/*
* We need to move both the parent and the dentry from the RCU domain
* to be properly refcounted. And the sequence number in the dentry
* validates *both* dentry counters, since we checked the sequence
* number of the parent after we got the child sequence number. So we
* know the parent must still be valid if the child sequence number is
*/
730 if (unlikely(!lockref_get_not_dead(&dentry->d_lockref)))
goto out;
732 if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) {
rcu_read_unlock();
734 dput(dentry);
goto drop_root_mnt;
}
/*
* Sequence counts matched. Now make sure that the root is
* still valid and get it if required.
*/
741 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
742 if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) {
rcu_read_unlock();
744 dput(dentry);
return -ECHILD;
}
}
rcu_read_unlock();
return 0;
out2:
753 nd->path.mnt = NULL;
out1:
755 nd->path.dentry = NULL;
out:
rcu_read_unlock();
drop_root_mnt:
759 if (!(nd->flags & LOOKUP_ROOT))
760 nd->root.mnt = NULL;
return -ECHILD;
}
static inline int d_revalidate(struct dentry *dentry, unsigned int flags)
{
766 if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE))
767 return dentry->d_op->d_revalidate(dentry, flags);
else
769 return 1;
}
/**
* complete_walk - successful completion of path walk
* @nd: pointer nameidata
*
* If we had been in RCU mode, drop out of it and legitimize nd->path.
* Revalidate the final result, unless we'd already done that during
* the path walk or the filesystem doesn't ask for it. Return 0 on
* success, -error on failure. In case of failure caller does not
* need to drop nd->path.
*/
static int complete_walk(struct nameidata *nd)
783 {
784 struct dentry *dentry = nd->path.dentry;
int status;
787 if (nd->flags & LOOKUP_RCU) {
788 if (!(nd->flags & LOOKUP_ROOT))
789 nd->root.mnt = NULL;
790 if (unlikely(unlazy_walk(nd)))
791 return -ECHILD;
}
794 if (likely(!(nd->flags & LOOKUP_JUMPED)))
795 return 0;
797 if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE)))
return 0;
800 status = dentry->d_op->d_weak_revalidate(dentry, nd->flags);
801 if (status > 0)
return 0;
if (!status)
805 status = -ESTALE;
return status;
808 }
static void set_root(struct nameidata *nd)
811 {
812 struct fs_struct *fs = current->fs;
814 if (nd->flags & LOOKUP_RCU) {
unsigned seq;
do {
seq = read_seqcount_begin(&fs->seq);
819 nd->root = fs->root;
820 nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
821 } while (read_seqcount_retry(&fs->seq, seq));
} else {
823 get_fs_root(fs, &nd->root);
}
825 }
static void path_put_conditional(struct path *path, struct nameidata *nd)
{
829 dput(path->dentry);
830 if (path->mnt != nd->path.mnt)
831 mntput(path->mnt);
}
static inline void path_to_nameidata(const struct path *path,
struct nameidata *nd)
{
837 if (!(nd->flags & LOOKUP_RCU)) {
838 dput(nd->path.dentry);
839 if (nd->path.mnt != path->mnt)
840 mntput(nd->path.mnt);
}
842 nd->path.mnt = path->mnt;
843 nd->path.dentry = path->dentry;
}
static int nd_jump_root(struct nameidata *nd)
847 {
848 if (nd->flags & LOOKUP_RCU) {
struct dentry *d;
850 nd->path = nd->root;
851 d = nd->path.dentry;
852 nd->inode = d->d_inode;
853 nd->seq = nd->root_seq;
854 if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq)))
855 return -ECHILD;
} else {
path_put(&nd->path);
858 nd->path = nd->root;
859 path_get(&nd->path);
860 nd->inode = nd->path.dentry->d_inode;
}
862 nd->flags |= LOOKUP_JUMPED;
863 return 0;
864 }
/*
* Helper to directly jump to a known parsed path from ->get_link,
* caller must have taken a reference to path beforehand.
*/
void nd_jump_link(struct path *path)
871 {
872 struct nameidata *nd = current->nameidata;
path_put(&nd->path);
875 nd->path = *path;
876 nd->inode = nd->path.dentry->d_inode;
877 nd->flags |= LOOKUP_JUMPED;
878 }
static inline void put_link(struct nameidata *nd)
{
882 struct saved *last = nd->stack + --nd->depth;
do_delayed_call(&last->done);
884 if (!(nd->flags & LOOKUP_RCU))
path_put(&last->link);
}
int sysctl_protected_symlinks __read_mostly = 0;
int sysctl_protected_hardlinks __read_mostly = 0;
/**
* may_follow_link - Check symlink following for unsafe situations
* @nd: nameidata pathwalk data
*
* In the case of the sysctl_protected_symlinks sysctl being enabled,
* CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is
* in a sticky world-writable directory. This is to protect privileged
* processes from failing races against path names that may change out
* from under them by way of other users creating malicious symlinks.
* It will permit symlinks to be followed only when outside a sticky
* world-writable directory, or when the uid of the symlink and follower
* match, or when the directory owner matches the symlink's owner.
*
* Returns 0 if following the symlink is allowed, -ve on error.
*/
static inline int may_follow_link(struct nameidata *nd)
{
const struct inode *inode;
const struct inode *parent;
kuid_t puid;
912 if (!sysctl_protected_symlinks)
return 0;
/* Allowed if owner and follower match. */
inode = nd->link_inode;
917 if (uid_eq(current_cred()->fsuid, inode->i_uid))
return 0;
/* Allowed if parent directory not sticky and world-writable. */
921 parent = nd->inode;
922 if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH))
return 0;
/* Allowed if parent directory and link owner match. */
926 puid = parent->i_uid;
927 if (uid_valid(puid) && uid_eq(puid, inode->i_uid))
return 0;
930 if (nd->flags & LOOKUP_RCU)
return -ECHILD;
933 audit_inode(nd->name, nd->stack[0].link.dentry, 0);
934 audit_log_link_denied("follow_link");
return -EACCES;
}
/**
* safe_hardlink_source - Check for safe hardlink conditions
* @inode: the source inode to hardlink from
*
* Return false if at least one of the following conditions:
* - inode is not a regular file
* - inode is setuid
* - inode is setgid and group-exec
* - access failure for read and write
*
* Otherwise returns true.
*/
static bool safe_hardlink_source(struct inode *inode)
{
952 umode_t mode = inode->i_mode;
/* Special files should not get pinned to the filesystem. */
955 if (!S_ISREG(mode))
return false;
/* Setuid files should not get pinned to the filesystem. */
959 if (mode & S_ISUID)
return false;
/* Executable setgid files should not get pinned to the filesystem. */
963 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
return false;
/* Hardlinking to unreadable or unwritable sources is dangerous. */
967 if (inode_permission(inode, MAY_READ | MAY_WRITE))
return false;
return true;
}
/**
* may_linkat - Check permissions for creating a hardlink
* @link: the source to hardlink from
*
* Block hardlink when all of:
* - sysctl_protected_hardlinks enabled
* - fsuid does not match inode
* - hardlink source is unsafe (see safe_hardlink_source() above)
* - not CAP_FOWNER in a namespace with the inode owner uid mapped
*
* Returns 0 if successful, -ve on error.
*/
static int may_linkat(struct path *link)
{
struct inode *inode;
989 if (!sysctl_protected_hardlinks)
return 0;
992 inode = link->dentry->d_inode;
/* Source inode owner (or CAP_FOWNER) can hardlink all they like,
* otherwise, it must be a safe source.
*/
997 if (safe_hardlink_source(inode) || inode_owner_or_capable(inode))
return 0;
1000 audit_log_link_denied("linkat");
1001 return -EPERM;
}
static __always_inline
const char *get_link(struct nameidata *nd)
{
1007 struct saved *last = nd->stack + nd->depth - 1;
1008 struct dentry *dentry = last->link.dentry;
1009 struct inode *inode = nd->link_inode;
int error;
const char *res;
1013 if (!(nd->flags & LOOKUP_RCU)) {
1014 touch_atime(&last->link);
1015 cond_resched();
1016 } else if (atime_needs_update_rcu(&last->link, inode)) {
1017 if (unlikely(unlazy_walk(nd)))
1018 return ERR_PTR(-ECHILD);
1019 touch_atime(&last->link);
}
1022 error = security_inode_follow_link(dentry, inode,
nd->flags & LOOKUP_RCU);
1024 if (unlikely(error))
1025 return ERR_PTR(error);
1027 nd->last_type = LAST_BIND;
1028 res = inode->i_link;
1029 if (!res) {
const char * (*get)(struct dentry *, struct inode *,
struct delayed_call *);
1032 get = inode->i_op->get_link;
1033 if (nd->flags & LOOKUP_RCU) {
1034 res = get(NULL, inode, &last->done);
1035 if (res == ERR_PTR(-ECHILD)) {
1036 if (unlikely(unlazy_walk(nd)))
return ERR_PTR(-ECHILD);
1038 res = get(dentry, inode, &last->done);
}
} else {
1041 res = get(dentry, inode, &last->done);
}
if (IS_ERR_OR_NULL(res))
return res;
}
1046 if (*res == '/') {
1047 if (!nd->root.mnt)
1048 set_root(nd);
1049 if (unlikely(nd_jump_root(nd)))
return ERR_PTR(-ECHILD);
1051 while (unlikely(*++res == '/'))
;
}
1054 if (!*res)
res = NULL;
return res;
}
/*
* follow_up - Find the mountpoint of path's vfsmount
*
* Given a path, find the mountpoint of its source file system.
* Replace @path with the path of the mountpoint in the parent mount.
* Up is towards /.
*
* Return 1 if we went up a level and 0 if we were already at the
* root.
*/
int follow_up(struct path *path)
1070 {
1071 struct mount *mnt = real_mount(path->mnt);
struct mount *parent;
struct dentry *mountpoint;
read_seqlock_excl(&mount_lock);
1076 parent = mnt->mnt_parent;
1077 if (parent == mnt) {
read_sequnlock_excl(&mount_lock);
1079 return 0;
}
1081 mntget(&parent->mnt);
1082 mountpoint = dget(mnt->mnt_mountpoint);
read_sequnlock_excl(&mount_lock);
1084 dput(path->dentry);
1085 path->dentry = mountpoint;
1086 mntput(path->mnt);
1087 path->mnt = &parent->mnt;
1088 return 1;
1089 }
EXPORT_SYMBOL(follow_up);
/*
* Perform an automount
* - return -EISDIR to tell follow_managed() to stop and return the path we
* were called with.
*/
static int follow_automount(struct path *path, struct nameidata *nd,
bool *need_mntput)
{
struct vfsmount *mnt;
int err;
1103 if (!path->dentry->d_op || !path->dentry->d_op->d_automount)
return -EREMOTE;
/* We don't want to mount if someone's just doing a stat -
* unless they're stat'ing a directory and appended a '/' to
* the name.
*
* We do, however, want to mount if someone wants to open or
* create a file of any type under the mountpoint, wants to
* traverse through the mountpoint or wants to open the
* mounted directory. Also, autofs may mark negative dentries
* as being automount points. These will need the attentions
* of the daemon to instantiate them before they can be used.
*/
1117 if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
1118 LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) &&
path->dentry->d_inode)
1120 return -EISDIR;
1122 nd->total_link_count++;
1123 if (nd->total_link_count >= 40)
1124 return -ELOOP;
1126 mnt = path->dentry->d_op->d_automount(path);
1127 if (IS_ERR(mnt)) {
/*
* The filesystem is allowed to return -EISDIR here to indicate
* it doesn't want to automount. For instance, autofs would do
* this so that its userspace daemon can mount on this dentry.
*
* However, we can only permit this if it's a terminal point in
* the path being looked up; if it wasn't then the remainder of
* the path is inaccessible and we should say so.
*/
1137 if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT))
1138 return -EREMOTE;
1139 return PTR_ERR(mnt);
}
1142 if (!mnt) /* mount collision */
1143 return 0;
1145 if (!*need_mntput) {
/* lock_mount() may release path->mnt on error */
1147 mntget(path->mnt);
*need_mntput = true;
}
1150 err = finish_automount(mnt, path);
1152 switch (err) {
case -EBUSY:
/* Someone else made a mount here whilst we were busy */
1155 return 0;
case 0:
path_put(path);
1158 path->mnt = mnt;
1159 path->dentry = dget(mnt->mnt_root);
return 0;
default:
return err;
}
}
/*
* Handle a dentry that is managed in some way.
* - Flagged for transit management (autofs)
* - Flagged as mountpoint
* - Flagged as automount point
*
* This may only be called in refwalk mode.
*
* Serialization is taken care of in namespace.c
*/
static int follow_managed(struct path *path, struct nameidata *nd)
1178 {
1179 struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */
unsigned managed;
1181 bool need_mntput = false;
1182 int ret = 0;
/* Given that we're not holding a lock here, we retain the value in a
* local variable for each dentry as we look at it so that we don't see
* the components of that value change under us */
1187 while (managed = READ_ONCE(path->dentry->d_flags),
managed &= DCACHE_MANAGED_DENTRY,
unlikely(managed != 0)) {
/* Allow the filesystem to manage the transit without i_mutex
* being held. */
1192 if (managed & DCACHE_MANAGE_TRANSIT) {
1193 BUG_ON(!path->dentry->d_op);
1194 BUG_ON(!path->dentry->d_op->d_manage);
1195 ret = path->dentry->d_op->d_manage(path, false);
1196 if (ret < 0)
break;
}
/* Transit to a mounted filesystem. */
1201 if (managed & DCACHE_MOUNTED) {
1202 struct vfsmount *mounted = lookup_mnt(path);
1203 if (mounted) {
1204 dput(path->dentry);
1205 if (need_mntput)
1206 mntput(path->mnt);
1207 path->mnt = mounted;
1208 path->dentry = dget(mounted->mnt_root);
need_mntput = true;
continue;
}
/* Something is mounted on this dentry in another
* namespace and/or whatever was mounted there in this
* namespace got unmounted before lookup_mnt() could
* get it */
}
/* Handle an automount point */
1220 if (managed & DCACHE_NEED_AUTOMOUNT) {
ret = follow_automount(path, nd, &need_mntput);
1222 if (ret < 0)
break;
continue;
}
/* We didn't change the current path point */
break;
}
1231 if (need_mntput && path->mnt == mnt)
1232 mntput(path->mnt);
1233 if (ret == -EISDIR || !ret)
1234 ret = 1;
if (need_mntput)
1236 nd->flags |= LOOKUP_JUMPED;
1237 if (unlikely(ret < 0))
path_put_conditional(path, nd);
return ret;
1240 }
int follow_down_one(struct path *path)
1243 {
struct vfsmount *mounted;
1246 mounted = lookup_mnt(path);
1247 if (mounted) {
1248 dput(path->dentry);
1249 mntput(path->mnt);
1250 path->mnt = mounted;
1251 path->dentry = dget(mounted->mnt_root);
1252 return 1;
}
return 0;
1255 }
EXPORT_SYMBOL(follow_down_one);
static inline int managed_dentry_rcu(const struct path *path)
{
1260 return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ?
1261 path->dentry->d_op->d_manage(path, true) : 0;
}
/*
* Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
* we meet a managed dentry that would need blocking.
*/
1268 static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
struct inode **inode, unsigned *seqp)
{
for (;;) {
struct mount *mounted;
/*
* Don't forget we might have a non-mountpoint managed dentry
* that wants to block transit.
*/
1277 switch (managed_dentry_rcu(path)) {
case -ECHILD:
default:
return false;
case -EISDIR:
1282 return true;
case 0:
break;
}
1287 if (!d_mountpoint(path->dentry))
return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT);
1290 mounted = __lookup_mnt(path->mnt, path->dentry);
1291 if (!mounted)
break;
1293 path->mnt = &mounted->mnt;
1294 path->dentry = mounted->mnt.mnt_root;
1295 nd->flags |= LOOKUP_JUMPED;
1296 *seqp = read_seqcount_begin(&path->dentry->d_seq);
/*
* Update the inode too. We don't need to re-check the
* dentry sequence number here after this d_inode read,
* because a mount-point is always pinned.
*/
1302 *inode = path->dentry->d_inode;
}
1304 return !read_seqretry(&mount_lock, nd->m_seq) &&
1305 !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT);
1306 }
static int follow_dotdot_rcu(struct nameidata *nd)
{
1310 struct inode *inode = nd->inode;
while (1) {
if (path_equal(&nd->path, &nd->root))
break;
1315 if (nd->path.dentry != nd->path.mnt->mnt_root) {
struct dentry *old = nd->path.dentry;
1317 struct dentry *parent = old->d_parent;
unsigned seq;
1320 inode = parent->d_inode;
seq = read_seqcount_begin(&parent->d_seq);
1322 if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq)))
1323 return -ECHILD;
1324 nd->path.dentry = parent;
1325 nd->seq = seq;
1326 if (unlikely(!path_connected(&nd->path)))
1327 return -ENOENT;
break;
} else {
struct mount *mnt = real_mount(nd->path.mnt);
1331 struct mount *mparent = mnt->mnt_parent;
1332 struct dentry *mountpoint = mnt->mnt_mountpoint;
1333 struct inode *inode2 = mountpoint->d_inode;
unsigned seq = read_seqcount_begin(&mountpoint->d_seq);
1335 if (unlikely(read_seqretry(&mount_lock, nd->m_seq)))
return -ECHILD;
1337 if (&mparent->mnt == nd->path.mnt)
break;
/* we know that mountpoint was pinned */
1340 nd->path.dentry = mountpoint;
1341 nd->path.mnt = &mparent->mnt;
1342 inode = inode2;
1343 nd->seq = seq;
}
}
1346 while (unlikely(d_mountpoint(nd->path.dentry))) {
struct mount *mounted;
1348 mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry);
1349 if (unlikely(read_seqretry(&mount_lock, nd->m_seq)))
return -ECHILD;
1351 if (!mounted)
break;
1353 nd->path.mnt = &mounted->mnt;
1354 nd->path.dentry = mounted->mnt.mnt_root;
1355 inode = nd->path.dentry->d_inode;
1356 nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
}
1358 nd->inode = inode;
1359 return 0;
}
/*
* Follow down to the covering mount currently visible to userspace. At each
* point, the filesystem owning that dentry may be queried as to whether the
* caller is permitted to proceed or not.
*/
int follow_down(struct path *path)
1368 {
unsigned managed;
int ret;
1372 while (managed = READ_ONCE(path->dentry->d_flags),
unlikely(managed & DCACHE_MANAGED_DENTRY)) {
/* Allow the filesystem to manage the transit without i_mutex
* being held.
*
* We indicate to the filesystem if someone is trying to mount
* something here. This gives autofs the chance to deny anyone
* other than its daemon the right to mount on its
* superstructure.
*
* The filesystem may sleep at this point.
*/
1384 if (managed & DCACHE_MANAGE_TRANSIT) {
1385 BUG_ON(!path->dentry->d_op);
1386 BUG_ON(!path->dentry->d_op->d_manage);
1387 ret = path->dentry->d_op->d_manage(path, false);
1388 if (ret < 0)
1389 return ret == -EISDIR ? 0 : ret;
}
/* Transit to a mounted filesystem. */
1393 if (managed & DCACHE_MOUNTED) {
1394 struct vfsmount *mounted = lookup_mnt(path);
1395 if (!mounted)
break;
1397 dput(path->dentry);
1398 mntput(path->mnt);
1399 path->mnt = mounted;
1400 path->dentry = dget(mounted->mnt_root);
continue;
}
/* Don't handle automount points here */
break;
}
1407 return 0;
1408 }
EXPORT_SYMBOL(follow_down);
/*
* Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
*/
static void follow_mount(struct path *path)
1415 {
1416 while (d_mountpoint(path->dentry)) {
1417 struct vfsmount *mounted = lookup_mnt(path);
1418 if (!mounted)
break;
1420 dput(path->dentry);
1421 mntput(path->mnt);
1422 path->mnt = mounted;
1423 path->dentry = dget(mounted->mnt_root);
}
1425 }
static int path_parent_directory(struct path *path)
1428 {
1429 struct dentry *old = path->dentry;
/* rare case of legitimate dget_parent()... */
1431 path->dentry = dget_parent(path->dentry);
1432 dput(old);
1433 if (unlikely(!path_connected(path)))
return -ENOENT;
1435 return 0;
1436 }
static int follow_dotdot(struct nameidata *nd)
{
while(1) {
1441 if (nd->path.dentry == nd->root.dentry &&
nd->path.mnt == nd->root.mnt) {
break;
}
1445 if (nd->path.dentry != nd->path.mnt->mnt_root) {
1446 int ret = path_parent_directory(&nd->path);
1447 if (ret)
return ret;
break;
}
1451 if (!follow_up(&nd->path))
break;
}
1454 follow_mount(&nd->path);
1455 nd->inode = nd->path.dentry->d_inode;
1456 return 0;
}
/*
* This looks up the name in dcache and possibly revalidates the found dentry.
* NULL is returned if the dentry does not exist in the cache.
*/
static struct dentry *lookup_dcache(const struct qstr *name,
struct dentry *dir,
unsigned int flags)
1466 {
1467 struct dentry *dentry = d_lookup(dir, name);
1468 if (dentry) {
int error = d_revalidate(dentry, flags);
1470 if (unlikely(error <= 0)) {
1471 if (!error)
1472 d_invalidate(dentry);
1473 dput(dentry);
1474 return ERR_PTR(error);
}
}
return dentry;
1478 }
/*
* Parent directory has inode locked exclusive. This is one
* and only case when ->lookup() gets called on non in-lookup
* dentries - as the matter of fact, this only gets called
* when directory is guaranteed to have no in-lookup children
* at all.
*/
static struct dentry *__lookup_hash(const struct qstr *name,
struct dentry *base, unsigned int flags)
1489 {
1490 struct dentry *dentry = lookup_dcache(name, base, flags);
struct dentry *old;
1492 struct inode *dir = base->d_inode;
1494 if (dentry)
return dentry;
/* Don't create child dentry for a dead directory. */
1498 if (unlikely(IS_DEADDIR(dir)))
1499 return ERR_PTR(-ENOENT);
1501 dentry = d_alloc(base, name);
1502 if (unlikely(!dentry))
1503 return ERR_PTR(-ENOMEM);
1505 old = dir->i_op->lookup(dir, dentry, flags);
1506 if (unlikely(old)) {
1507 dput(dentry);
dentry = old;
}
return dentry;
1511 }
static int lookup_fast(struct nameidata *nd,
struct path *path, struct inode **inode,
unsigned *seqp)
1516 {
1517 struct vfsmount *mnt = nd->path.mnt;
1518 struct dentry *dentry, *parent = nd->path.dentry;
int status = 1;
int err;
/*
* Rename seqlock is not required here because in the off chance
* of a false negative due to a concurrent rename, the caller is
* going to fall back to non-racy lookup.
*/
1527 if (nd->flags & LOOKUP_RCU) {
unsigned seq;
bool negative;
1530 dentry = __d_lookup_rcu(parent, &nd->last, &seq);
1531 if (unlikely(!dentry)) {
1532 if (unlazy_walk(nd))
1533 return -ECHILD;
return 0;
}
/*
* This sequence count validates that the inode matches
* the dentry name information from lookup.
*/
1541 *inode = d_backing_inode(dentry);
negative = d_is_negative(dentry);
1543 if (unlikely(read_seqcount_retry(&dentry->d_seq, seq)))
return -ECHILD;
/*
* This sequence count validates that the parent had no
* changes while we did the lookup of the dentry above.
*
* The memory barrier in read_seqcount_begin of child is
* enough, we can use __read_seqcount_retry here.
*/
1553 if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq)))
return -ECHILD;
1556 *seqp = seq;
status = d_revalidate(dentry, nd->flags);
1558 if (likely(status > 0)) {
/*
* Note: do negative dentry check after revalidation in
* case that drops it.
*/
1563 if (unlikely(negative))
return -ENOENT;
1565 path->mnt = mnt;
1566 path->dentry = dentry;
1567 if (likely(__follow_mount_rcu(nd, path, inode, seqp)))
1568 return 1;
}
1570 if (unlazy_child(nd, dentry, seq))
1571 return -ECHILD;
1572 if (unlikely(status == -ECHILD))
/* we'd been told to redo it in non-rcu mode */
status = d_revalidate(dentry, nd->flags);
} else {
1576 dentry = __d_lookup(parent, &nd->last);
1577 if (unlikely(!dentry))
1578 return 0;
status = d_revalidate(dentry, nd->flags);
}
1581 if (unlikely(status <= 0)) {
1582 if (!status)
1583 d_invalidate(dentry);
1584 dput(dentry);
1585 return status;
}
1587 if (unlikely(d_is_negative(dentry))) {
1588 dput(dentry);
1589 return -ENOENT;
}
1592 path->mnt = mnt;
1593 path->dentry = dentry;
1594 err = follow_managed(path, nd);
1595 if (likely(err > 0))
1596 *inode = d_backing_inode(path->dentry);
return err;
1598 }
/* Fast lookup failed, do it the slow way */
static struct dentry *__lookup_slow(const struct qstr *name,
struct dentry *dir,
unsigned int flags)
1604 {
struct dentry *dentry, *old;
1606 struct inode *inode = dir->d_inode;
1607 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
/* Don't go there if it's already dead */
1610 if (unlikely(IS_DEADDIR(inode)))
1611 return ERR_PTR(-ENOENT);
again:
1613 dentry = d_alloc_parallel(dir, name, &wq);
1614 if (IS_ERR(dentry))
return dentry;
1616 if (unlikely(!d_in_lookup(dentry))) {
1617 if (!(flags & LOOKUP_NO_REVAL)) {
int error = d_revalidate(dentry, flags);
1619 if (unlikely(error <= 0)) {
1620 if (!error) {
1621 d_invalidate(dentry);
1622 dput(dentry);
1623 goto again;
}
1625 dput(dentry);
1626 dentry = ERR_PTR(error);
}
}
} else {
1630 old = inode->i_op->lookup(inode, dentry, flags);
d_lookup_done(dentry);
1632 if (unlikely(old)) {
1633 dput(dentry);
dentry = old;
}
}
return dentry;
1638 }
static struct dentry *lookup_slow(const struct qstr *name,
struct dentry *dir,
unsigned int flags)
1643 {
struct inode *inode = dir->d_inode;
struct dentry *res;
inode_lock_shared(inode);
1647 res = __lookup_slow(name, dir, flags);
inode_unlock_shared(inode);
return res;
1650 }
static inline int may_lookup(struct nameidata *nd)
{
1654 if (nd->flags & LOOKUP_RCU) {
1655 int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK);
1656 if (err != -ECHILD)
return err;
1658 if (unlazy_walk(nd))
return -ECHILD;
}
1661 return inode_permission(nd->inode, MAY_EXEC);
}
static inline int handle_dots(struct nameidata *nd, int type)
{
1666 if (type == LAST_DOTDOT) {
1667 if (!nd->root.mnt)
1668 set_root(nd);
1669 if (nd->flags & LOOKUP_RCU) {
return follow_dotdot_rcu(nd);
} else
return follow_dotdot(nd);
}
1674 return 0;
}
static int pick_link(struct nameidata *nd, struct path *link,
struct inode *inode, unsigned seq)
1679 {
int error;
struct saved *last;
1682 if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) {
path_to_nameidata(link, nd);
1684 return -ELOOP;
}
1686 if (!(nd->flags & LOOKUP_RCU)) {
1687 if (link->mnt == nd->path.mnt)
1688 mntget(link->mnt);
}
error = nd_alloc_stack(nd);
1691 if (unlikely(error)) {
1692 if (error == -ECHILD) {
1693 if (unlikely(!legitimize_path(nd, link, seq))) {
drop_links(nd);
1695 nd->depth = 0;
1696 nd->flags &= ~LOOKUP_RCU;
1697 nd->path.mnt = NULL;
1698 nd->path.dentry = NULL;
1699 if (!(nd->flags & LOOKUP_ROOT))
1700 nd->root.mnt = NULL;
rcu_read_unlock();
1702 } else if (likely(unlazy_walk(nd)) == 0)
error = nd_alloc_stack(nd);
}
1705 if (error) {
path_put(link);
1707 return error;
}
}
1711 last = nd->stack + nd->depth++;
1712 last->link = *link;
clear_delayed_call(&last->done);
1714 nd->link_inode = inode;
1715 last->seq = seq;
1716 return 1;
1717 }
enum {WALK_FOLLOW = 1, WALK_MORE = 2};
/*
* Do we need to follow links? We _really_ want to be able
* to do this check without having to look at inode->i_op,
* so we keep a cache of "no, this doesn't need follow_link"
* for the common case.
*/
static inline int step_into(struct nameidata *nd, struct path *path,
int flags, struct inode *inode, unsigned seq)
{
1730 if (!(flags & WALK_MORE) && nd->depth)
put_link(nd);
1732 if (likely(!d_is_symlink(path->dentry)) ||
1733 !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) {
/* not a symlink or should not follow */
path_to_nameidata(path, nd);
1736 nd->inode = inode;
1737 nd->seq = seq;
return 0;
}
/* make sure that d_is_symlink above matches inode */
1741 if (nd->flags & LOOKUP_RCU) {
1742 if (read_seqcount_retry(&path->dentry->d_seq, seq))
1743 return -ECHILD;
}
1745 return pick_link(nd, path, inode, seq);
}
static int walk_component(struct nameidata *nd, int flags)
1749 {
struct path path;
struct inode *inode;
unsigned seq;
int err;
/*
* "." and ".." are special - ".." especially so because it has
* to be able to know about the current root directory and
* parent relationships.
*/
1759 if (unlikely(nd->last_type != LAST_NORM)) {
err = handle_dots(nd, nd->last_type);
1761 if (!(flags & WALK_MORE) && nd->depth)
put_link(nd);
return err;
}
1765 err = lookup_fast(nd, &path, &inode, &seq);
1766 if (unlikely(err <= 0)) {
1767 if (err < 0)
return err;
1769 path.dentry = lookup_slow(&nd->last, nd->path.dentry,
nd->flags);
1771 if (IS_ERR(path.dentry))
return PTR_ERR(path.dentry);
1774 path.mnt = nd->path.mnt;
1775 err = follow_managed(&path, nd);
1776 if (unlikely(err < 0))
return err;
1779 if (unlikely(d_is_negative(path.dentry))) {
path_to_nameidata(&path, nd);
1781 return -ENOENT;
}
1784 seq = 0; /* we are already out of RCU mode */
1785 inode = d_backing_inode(path.dentry);
}
return step_into(nd, &path, flags, inode, seq);
1789 }
/*
* We can do the critical dentry name comparison and hashing
* operations one word at a time, but we are limited to:
*
* - Architectures with fast unaligned word accesses. We could
* do a "get_unaligned()" if this helps and is sufficiently
* fast.
*
* - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we
* do not trap on the (extremely unlikely) case of a page
* crossing operation.
*
* - Furthermore, we need an efficient 64-bit compile for the
* 64-bit case in order to generate the "number of bytes in
* the final mask". Again, that could be replaced with a
* efficient population count instruction or similar.
*/
#ifdef CONFIG_DCACHE_WORD_ACCESS
#include <asm/word-at-a-time.h>
#ifdef HASH_MIX
/* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */
#elif defined(CONFIG_64BIT)
/*
* Register pressure in the mixing function is an issue, particularly
* on 32-bit x86, but almost any function requires one state value and
* one temporary. Instead, use a function designed for two state values
* and no temporaries.
*
* This function cannot create a collision in only two iterations, so
* we have two iterations to achieve avalanche. In those two iterations,
* we have six layers of mixing, which is enough to spread one bit's
* influence out to 2^6 = 64 state bits.
*
* Rotate constants are scored by considering either 64 one-bit input
* deltas or 64*63/2 = 2016 two-bit input deltas, and finding the
* probability of that delta causing a change to each of the 128 output
* bits, using a sample of random initial states.
*
* The Shannon entropy of the computed probabilities is then summed
* to produce a score. Ideally, any input change has a 50% chance of
* toggling any given output bit.
*
* Mixing scores (in bits) for (12,45):
* Input delta: 1-bit 2-bit
* 1 round: 713.3 42542.6
* 2 rounds: 2753.7 140389.8
* 3 rounds: 5954.1 233458.2
* 4 rounds: 7862.6 256672.2
* Perfect: 8192 258048
* (64*128) (64*63/2 * 128)
*/
#define HASH_MIX(x, y, a) \
( x ^= (a), \
y ^= x, x = rol64(x,12),\
x += y, y = rol64(y,45),\
y *= 9 )
/*
* Fold two longs into one 32-bit hash value. This must be fast, but
* latency isn't quite as critical, as there is a fair bit of additional
* work done before the hash value is used.
*/
static inline unsigned int fold_hash(unsigned long x, unsigned long y)
{
1859 y ^= x * GOLDEN_RATIO_64;
1860 y *= GOLDEN_RATIO_64;
1861 return y >> 32;
}
#else /* 32-bit case */
/*
* Mixing scores (in bits) for (7,20):
* Input delta: 1-bit 2-bit
* 1 round: 330.3 9201.6
* 2 rounds: 1246.4 25475.4
* 3 rounds: 1907.1 31295.1
* 4 rounds: 2042.3 31718.6
* Perfect: 2048 31744
* (32*64) (32*31/2 * 64)
*/
#define HASH_MIX(x, y, a) \
( x ^= (a), \
y ^= x, x = rol32(x, 7),\
x += y, y = rol32(y,20),\
y *= 9 )
static inline unsigned int fold_hash(unsigned long x, unsigned long y)
{
/* Use arch-optimized multiply if one exists */
return __hash_32(y ^ __hash_32(x));
}
#endif
/*
* Return the hash of a string of known length. This is carfully
* designed to match hash_name(), which is the more critical function.
* In particular, we must end by hashing a final word containing 0..7
* payload bytes, to match the way that hash_name() iterates until it
* finds the delimiter after the name.
*/
unsigned int full_name_hash(const void *salt, const char *name, unsigned int len)
1898 {
1899 unsigned long a, x = 0, y = (unsigned long)salt;
for (;;) {
1902 if (!len)
goto done;
a = load_unaligned_zeropad(name);
1905 if (len < sizeof(unsigned long))
break;
1907 HASH_MIX(x, y, a);
1908 name += sizeof(unsigned long);
len -= sizeof(unsigned long);
}
1911 x ^= a & bytemask_from_count(len);
done:
return fold_hash(x, y);
1914 }
EXPORT_SYMBOL(full_name_hash);
/* Return the "hash_len" (hash and length) of a null-terminated string */
u64 hashlen_string(const void *salt, const char *name)
1919 {
1920 unsigned long a = 0, x = 0, y = (unsigned long)salt;
unsigned long adata, mask, len;
const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
1924 len = 0;
1925 goto inside;
do {
1928 HASH_MIX(x, y, a);
1929 len += sizeof(unsigned long);
inside:
a = load_unaligned_zeropad(name+len);
1932 } while (!has_zero(a, &adata, &constants));
adata = prep_zero_mask(a, adata, &constants);
mask = create_zero_mask(adata);
1936 x ^= a & zero_bytemask(mask);
1938 return hashlen_create(fold_hash(x, y), len + find_zero(mask));
1939 }
EXPORT_SYMBOL(hashlen_string);
/*
* Calculate the length and hash of the path component, and
* return the "hash_len" as the result.
*/
static inline u64 hash_name(const void *salt, const char *name)
{
1948 unsigned long a = 0, b, x = 0, y = (unsigned long)salt;
unsigned long adata, bdata, mask, len;
const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
1952 len = 0;
goto inside;
do {
1956 HASH_MIX(x, y, a);
1957 len += sizeof(unsigned long);
inside:
a = load_unaligned_zeropad(name+len);
1960 b = a ^ REPEAT_BYTE('/');
1961 } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants)));
adata = prep_zero_mask(a, adata, &constants);
bdata = prep_zero_mask(b, bdata, &constants);
mask = create_zero_mask(adata | bdata);
1966 x ^= a & zero_bytemask(mask);
1968 return hashlen_create(fold_hash(x, y), len + find_zero(mask));
}
#else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */
/* Return the hash of a string of known length */
unsigned int full_name_hash(const void *salt, const char *name, unsigned int len)
{
unsigned long hash = init_name_hash(salt);
while (len--)
hash = partial_name_hash((unsigned char)*name++, hash);
return end_name_hash(hash);
}
EXPORT_SYMBOL(full_name_hash);
/* Return the "hash_len" (hash and length) of a null-terminated string */
u64 hashlen_string(const void *salt, const char *name)
{
unsigned long hash = init_name_hash(salt);
unsigned long len = 0, c;
c = (unsigned char)*name;
while (c) {
len++;
hash = partial_name_hash(c, hash);
c = (unsigned char)name[len];
}
return hashlen_create(end_name_hash(hash), len);
}
EXPORT_SYMBOL(hashlen_string);
/*
* We know there's a real path component here of at least
* one character.
*/
static inline u64 hash_name(const void *salt, const char *name)
{
unsigned long hash = init_name_hash(salt);
unsigned long len = 0, c;
c = (unsigned char)*name;
do {
len++;
hash = partial_name_hash(c, hash);
c = (unsigned char)name[len];
} while (c && c != '/');
return hashlen_create(end_name_hash(hash), len);
}
#endif
/*
* Name resolution.
* This is the basic name resolution function, turning a pathname into
* the final dentry. We expect 'base' to be positive and a directory.
*
* Returns 0 and nd will have valid dentry and mnt on success.
* Returns error and drops reference to input namei data on failure.
*/
static int link_path_walk(const char *name, struct nameidata *nd)
2028 {
int err;
2031 while (*name=='/')
2032 name++;
2033 if (!*name)
2034 return 0;
/* At this point we know we have a real path component. */
for(;;) {
u64 hash_len;
int type;
err = may_lookup(nd);
2042 if (err)
return err;
2045 hash_len = hash_name(nd->path.dentry, name);
type = LAST_NORM;
2048 if (name[0] == '.') switch (hashlen_len(hash_len)) {
case 2:
2050 if (name[1] == '.') {
2051 type = LAST_DOTDOT;
2052 nd->flags |= LOOKUP_JUMPED;
}
break;
case 1:
2056 type = LAST_DOT;
}
if (likely(type == LAST_NORM)) {
struct dentry *parent = nd->path.dentry;
2060 nd->flags &= ~LOOKUP_JUMPED;
2061 if (unlikely(parent->d_flags & DCACHE_OP_HASH)) {
2062 struct qstr this = { { .hash_len = hash_len }, .name = name };
2063 err = parent->d_op->d_hash(parent, &this);
2064 if (err < 0)
return err;
2066 hash_len = this.hash_len;
2067 name = this.name;
}
}
2071 nd->last.hash_len = hash_len;
2072 nd->last.name = name;
2073 nd->last_type = type;
2075 name += hashlen_len(hash_len);
2076 if (!*name)
goto OK;
/*
* If it wasn't NUL, we know it was '/'. Skip that
* slash, and continue until no more slashes.
*/
do {
2083 name++;
2084 } while (unlikely(*name == '/'));
2085 if (unlikely(!*name)) {
OK:
/* pathname body, done */
2088 if (!nd->depth)
return 0;
2090 name = nd->stack[nd->depth - 1].name;
/* trailing symlink, done */
2092 if (!name)
return 0;
/* last component of nested symlink */
2095 err = walk_component(nd, WALK_FOLLOW);
} else {
/* not the last component */
2098 err = walk_component(nd, WALK_FOLLOW | WALK_MORE);
}
2100 if (err < 0)
return err;
2103 if (err) {
const char *s = get_link(nd);
2106 if (IS_ERR(s))
2107 return PTR_ERR(s);
err = 0;
2109 if (unlikely(!s)) {
/* jumped */
put_link(nd);
} else {
2113 nd->stack[nd->depth - 1].name = name;
name = s;
2115 continue;
}
}
2118 if (unlikely(!d_can_lookup(nd->path.dentry))) {
2119 if (nd->flags & LOOKUP_RCU) {
2120 if (unlazy_walk(nd))
return -ECHILD;
}
2123 return -ENOTDIR;
}
}
2126 }
static const char *path_init(struct nameidata *nd, unsigned flags)
2129 {
2130 const char *s = nd->name->name;
2132 if (!*s)
2133 flags &= ~LOOKUP_RCU;
2135 nd->last_type = LAST_ROOT; /* if there are only slashes... */
2136 nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT;
nd->depth = 0;
2138 if (flags & LOOKUP_ROOT) {
2139 struct dentry *root = nd->root.dentry;
2140 struct inode *inode = root->d_inode;
2141 if (*s && unlikely(!d_can_lookup(root)))
return ERR_PTR(-ENOTDIR);
2143 nd->path = nd->root;
2144 nd->inode = inode;
2145 if (flags & LOOKUP_RCU) {
rcu_read_lock();
2147 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
2148 nd->root_seq = nd->seq;
2149 nd->m_seq = read_seqbegin(&mount_lock);
} else {
2151 path_get(&nd->path);
}
return s;
}
2156 nd->root.mnt = NULL;
2157 nd->path.mnt = NULL;
2158 nd->path.dentry = NULL;
2160 nd->m_seq = read_seqbegin(&mount_lock);
2161 if (*s == '/') {
if (flags & LOOKUP_RCU)
rcu_read_lock();
2164 set_root(nd);
2165 if (likely(!nd_jump_root(nd)))
return s;
2167 nd->root.mnt = NULL;
rcu_read_unlock();
2169 return ERR_PTR(-ECHILD);
2170 } else if (nd->dfd == AT_FDCWD) {
2171 if (flags & LOOKUP_RCU) {
2172 struct fs_struct *fs = current->fs;
unsigned seq;
rcu_read_lock();
do {
seq = read_seqcount_begin(&fs->seq);
2179 nd->path = fs->pwd;
2180 nd->inode = nd->path.dentry->d_inode;
2181 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
2182 } while (read_seqcount_retry(&fs->seq, seq));
} else {
2184 get_fs_pwd(current->fs, &nd->path);
2185 nd->inode = nd->path.dentry->d_inode;
}
return s;
} else {
/* Caller must check execute permissions on the starting path component */
struct fd f = fdget_raw(nd->dfd);
struct dentry *dentry;
2193 if (!f.file)
2194 return ERR_PTR(-EBADF);
2196 dentry = f.file->f_path.dentry;
2198 if (*s) {
2199 if (!d_can_lookup(dentry)) {
fdput(f);
2201 return ERR_PTR(-ENOTDIR);
}
}
2205 nd->path = f.file->f_path;
2206 if (flags & LOOKUP_RCU) {
rcu_read_lock();
2208 nd->inode = nd->path.dentry->d_inode;
2209 nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
} else {
2211 path_get(&nd->path);
2212 nd->inode = nd->path.dentry->d_inode;
}
fdput(f);
return s;
}
2217 }
static const char *trailing_symlink(struct nameidata *nd)
2220 {
const char *s;
int error = may_follow_link(nd);
if (unlikely(error))
return ERR_PTR(error);
2225 nd->flags |= LOOKUP_PARENT;
2226 nd->stack[0].name = NULL;
s = get_link(nd);
2228 return s ? s : "";
2229 }
static inline int lookup_last(struct nameidata *nd)
{
2233 if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len])
2234 nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
2236 nd->flags &= ~LOOKUP_PARENT;
2237 return walk_component(nd, 0);
}
static int handle_lookup_down(struct nameidata *nd)
{
2242 struct path path = nd->path;
2243 struct inode *inode = nd->inode;
2244 unsigned seq = nd->seq;
int err;
2247 if (nd->flags & LOOKUP_RCU) {
/*
* don't bother with unlazy_walk on failure - we are
* at the very beginning of walk, so we lose nothing
* if we simply redo everything in non-RCU mode
*/
2253 if (unlikely(!__follow_mount_rcu(nd, &path, &inode, &seq)))
2254 return -ECHILD;
} else {
2256 dget(path.dentry);
2257 err = follow_managed(&path, nd);
2258 if (unlikely(err < 0))
return err;
2260 inode = d_backing_inode(path.dentry);
2261 seq = 0;
}
path_to_nameidata(&path, nd);
2264 nd->inode = inode;
2265 nd->seq = seq;
return 0;
}
/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path)
2271 {
2272 const char *s = path_init(nd, flags);
int err;
2275 if (IS_ERR(s))
return PTR_ERR(s);
2278 if (unlikely(flags & LOOKUP_DOWN)) {
err = handle_lookup_down(nd);
if (unlikely(err < 0)) {
terminate_walk(nd);
return err;
}
}
2286 while (!(err = link_path_walk(s, nd))
2287 && ((err = lookup_last(nd)) > 0)) {
2288 s = trailing_symlink(nd);
2289 if (IS_ERR(s)) {
err = PTR_ERR(s);
break;
}
}
2294 if (!err)
2295 err = complete_walk(nd);
2297 if (!err && nd->flags & LOOKUP_DIRECTORY)
2298 if (!d_can_lookup(nd->path.dentry))
2299 err = -ENOTDIR;
if (!err) {
2301 *path = nd->path;
2302 nd->path.mnt = NULL;
2303 nd->path.dentry = NULL;
}
2305 terminate_walk(nd);
return err;
2307 }
static int filename_lookup(int dfd, struct filename *name, unsigned flags,
struct path *path, struct path *root)
2311 {
int retval;
struct nameidata nd;
2314 if (IS_ERR(name))
2315 return PTR_ERR(name);
2316 if (unlikely(root)) {
2317 nd.root = *root;
2318 flags |= LOOKUP_ROOT;
}
set_nameidata(&nd, dfd, name);
2321 retval = path_lookupat(&nd, flags | LOOKUP_RCU, path);
2322 if (unlikely(retval == -ECHILD))
2323 retval = path_lookupat(&nd, flags, path);
2324 if (unlikely(retval == -ESTALE))
2325 retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path);
2327 if (likely(!retval))
audit_inode(name, path->dentry, flags & LOOKUP_PARENT);
2329 restore_nameidata();
2330 putname(name);
return retval;
2332 }
/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
static int path_parentat(struct nameidata *nd, unsigned flags,
struct path *parent)
2337 {
2338 const char *s = path_init(nd, flags);
int err;
2340 if (IS_ERR(s))
2341 return PTR_ERR(s);
2342 err = link_path_walk(s, nd);
2343 if (!err)
2344 err = complete_walk(nd);
2345 if (!err) {
2346 *parent = nd->path;
2347 nd->path.mnt = NULL;
2348 nd->path.dentry = NULL;
}
2350 terminate_walk(nd);
return err;
2352 }
static struct filename *filename_parentat(int dfd, struct filename *name,
unsigned int flags, struct path *parent,
struct qstr *last, int *type)
2357 {
int retval;
struct nameidata nd;
2361 if (IS_ERR(name))
return name;
set_nameidata(&nd, dfd, name);
2364 retval = path_parentat(&nd, flags | LOOKUP_RCU, parent);
2365 if (unlikely(retval == -ECHILD))
2366 retval = path_parentat(&nd, flags, parent);
2367 if (unlikely(retval == -ESTALE))
2368 retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent);
2369 if (likely(!retval)) {
2370 *last = nd.last;
2371 *type = nd.last_type;
audit_inode(name, parent->dentry, LOOKUP_PARENT);
} else {
2374 putname(name);
2375 name = ERR_PTR(retval);
}
2377 restore_nameidata();
return name;
2379 }
/* does lookup, returns the object with parent locked */
struct dentry *kern_path_locked(const char *name, struct path *path)
2383 {
struct filename *filename;
struct dentry *d;
struct qstr last;
int type;
2389 filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path,
&last, &type);
2391 if (IS_ERR(filename))
2392 return ERR_CAST(filename);
2393 if (unlikely(type != LAST_NORM)) {
path_put(path);
2395 putname(filename);
2396 return ERR_PTR(-EINVAL);
}
inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT);
2399 d = __lookup_hash(&last, path->dentry, 0);
2400 if (IS_ERR(d)) {
2401 inode_unlock(path->dentry->d_inode);
path_put(path);
}
2404 putname(filename);
return d;
2406 }
int kern_path(const char *name, unsigned int flags, struct path *path)
2409 {
2410 return filename_lookup(AT_FDCWD, getname_kernel(name),
flags, path, NULL);
2412 }
EXPORT_SYMBOL(kern_path);
/**
* vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
* @dentry: pointer to dentry of the base directory
* @mnt: pointer to vfs mount of the base directory
* @name: pointer to file name
* @flags: lookup flags
* @path: pointer to struct path to fill
*/
int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
const char *name, unsigned int flags,
struct path *path)
2426 {
2427 struct path root = {.mnt = mnt, .dentry = dentry};
/* the first argument of filename_lookup() is ignored with root */
2429 return filename_lookup(AT_FDCWD, getname_kernel(name),
flags , path, &root);
2431 }
EXPORT_SYMBOL(vfs_path_lookup);
static int lookup_one_len_common(const char *name, struct dentry *base,
int len, struct qstr *this)
2436 {
2437 this->name = name;
2438 this->len = len;
2439 this->hash = full_name_hash(base, name, len);
2440 if (!len)
2441 return -EACCES;
2443 if (unlikely(name[0] == '.')) {
2444 if (len < 2 || (len == 2 && name[1] == '.'))
return -EACCES;
}
2448 while (len--) {
2449 unsigned int c = *(const unsigned char *)name++;
2450 if (c == '/' || c == '\0')
return -EACCES;
}
/*
* See if the low-level filesystem might want
* to use its own hash..
*/
2457 if (base->d_flags & DCACHE_OP_HASH) {
2458 int err = base->d_op->d_hash(base, this);
2459 if (err < 0)
return err;
}
2463 return inode_permission(base->d_inode, MAY_EXEC);
2464 }
/**
* lookup_one_len - filesystem helper to lookup single pathname component
* @name: pathname component to lookup
* @base: base directory to lookup from
* @len: maximum length @len should be interpreted to
*
* Note that this routine is purely a helper for filesystem usage and should
* not be called by generic code.
*
* The caller must hold base->i_mutex.
*/
struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
2478 {
struct dentry *dentry;
struct qstr this;
int err;
2483 WARN_ON_ONCE(!inode_is_locked(base->d_inode));
2485 err = lookup_one_len_common(name, base, len, &this);
2486 if (err)
2487 return ERR_PTR(err);
2489 dentry = lookup_dcache(&this, base, 0);
2490 return dentry ? dentry : __lookup_slow(&this, base, 0);
2491 }
EXPORT_SYMBOL(lookup_one_len);
/**
* lookup_one_len_unlocked - filesystem helper to lookup single pathname component
* @name: pathname component to lookup
* @base: base directory to lookup from
* @len: maximum length @len should be interpreted to
*
* Note that this routine is purely a helper for filesystem usage and should
* not be called by generic code.
*
* Unlike lookup_one_len, it should be called without the parent
* i_mutex held, and will take the i_mutex itself if necessary.
*/
struct dentry *lookup_one_len_unlocked(const char *name,
struct dentry *base, int len)
2508 {
struct qstr this;
int err;
struct dentry *ret;
2513 err = lookup_one_len_common(name, base, len, &this);
2514 if (err)
2515 return ERR_PTR(err);
2517 ret = lookup_dcache(&this, base, 0);
2518 if (!ret)
2519 ret = lookup_slow(&this, base, 0);
return ret;
2521 }
EXPORT_SYMBOL(lookup_one_len_unlocked);
#ifdef CONFIG_UNIX98_PTYS
int path_pts(struct path *path)
2526 {
/* Find something mounted on "pts" in the same directory as
* the input path.
*/
struct dentry *child, *parent;
struct qstr this;
int ret;
2534 ret = path_parent_directory(path);
2535 if (ret)
return ret;
2538 parent = path->dentry;
2539 this.name = "pts";
2540 this.len = 3;
2541 child = d_hash_and_lookup(parent, &this);
2542 if (!child)
2543 return -ENOENT;
2545 path->dentry = child;
2546 dput(parent);
2547 follow_mount(path);
2548 return 0;
2549 }
#endif
int user_path_at_empty(int dfd, const char __user *name, unsigned flags,
struct path *path, int *empty)
2554 {
2555 return filename_lookup(dfd, getname_flags(name, flags, empty),
flags, path, NULL);
2557 }
EXPORT_SYMBOL(user_path_at_empty);
/**
* mountpoint_last - look up last component for umount
* @nd: pathwalk nameidata - currently pointing at parent directory of "last"
*
* This is a special lookup_last function just for umount. In this case, we
* need to resolve the path without doing any revalidation.
*
* The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since
* mountpoints are always pinned in the dcache, their ancestors are too. Thus,
* in almost all cases, this lookup will be served out of the dcache. The only
* cases where it won't are if nd->last refers to a symlink or the path is
* bogus and it doesn't exist.
*
* Returns:
* -error: if there was an error during lookup. This includes -ENOENT if the
* lookup found a negative dentry.
*
* 0: if we successfully resolved nd->last and found it to not to be a
* symlink that needs to be followed.
*
* 1: if we successfully resolved nd->last and found it to be a symlink
* that needs to be followed.
*/
static int
mountpoint_last(struct nameidata *nd)
{
int error = 0;
2587 struct dentry *dir = nd->path.dentry;
struct path path;
/* If we're in rcuwalk, drop out of it to handle last component */
2591 if (nd->flags & LOOKUP_RCU) {
2592 if (unlazy_walk(nd))
return -ECHILD;
}
2596 nd->flags &= ~LOOKUP_PARENT;
2598 if (unlikely(nd->last_type != LAST_NORM)) {
error = handle_dots(nd, nd->last_type);
if (error)
return error;
2602 path.dentry = dget(nd->path.dentry);
} else {
2604 path.dentry = d_lookup(dir, &nd->last);
2605 if (!path.dentry) {
/*
* No cached dentry. Mounted dentries are pinned in the
* cache, so that means that this dentry is probably
* a symlink or the path doesn't actually point
* to a mounted dentry.
*/
2612 path.dentry = lookup_slow(&nd->last, dir,
nd->flags | LOOKUP_NO_REVAL);
2614 if (IS_ERR(path.dentry))
return PTR_ERR(path.dentry);
}
}
2618 if (d_is_negative(path.dentry)) {
2619 dput(path.dentry);
2620 return -ENOENT;
}
2622 path.mnt = nd->path.mnt;
2623 return step_into(nd, &path, 0, d_backing_inode(path.dentry), 0);
}
/**
* path_mountpoint - look up a path to be umounted
* @nd: lookup context
* @flags: lookup flags
* @path: pointer to container for result
*
* Look up the given name, but don't attempt to revalidate the last component.
* Returns 0 and "path" will be valid on success; Returns error otherwise.
*/
static int
path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path)
2637 {
2638 const char *s = path_init(nd, flags);
int err;
2640 if (IS_ERR(s))
2641 return PTR_ERR(s);
2642 while (!(err = link_path_walk(s, nd)) &&
(err = mountpoint_last(nd)) > 0) {
2644 s = trailing_symlink(nd);
2645 if (IS_ERR(s)) {
err = PTR_ERR(s);
break;
}
}
2650 if (!err) {
2651 *path = nd->path;
2652 nd->path.mnt = NULL;
2653 nd->path.dentry = NULL;
2654 follow_mount(path);
}
2656 terminate_walk(nd);
return err;
2658 }
static int
filename_mountpoint(int dfd, struct filename *name, struct path *path,
unsigned int flags)
2663 {
struct nameidata nd;
int error;
2666 if (IS_ERR(name))
2667 return PTR_ERR(name);
set_nameidata(&nd, dfd, name);
2669 error = path_mountpoint(&nd, flags | LOOKUP_RCU, path);
2670 if (unlikely(error == -ECHILD))
2671 error = path_mountpoint(&nd, flags, path);
2672 if (unlikely(error == -ESTALE))
2673 error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path);
2674 if (likely(!error))
audit_inode(name, path->dentry, 0);
2676 restore_nameidata();
2677 putname(name);
return error;
2679 }
/**
* user_path_mountpoint_at - lookup a path from userland in order to umount it
* @dfd: directory file descriptor
* @name: pathname from userland
* @flags: lookup flags
* @path: pointer to container to hold result
*
* A umount is a special case for path walking. We're not actually interested
* in the inode in this situation, and ESTALE errors can be a problem. We
* simply want track down the dentry and vfsmount attached at the mountpoint
* and avoid revalidating the last component.
*
* Returns 0 and populates "path" on success.
*/
int
user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags,
struct path *path)
2698 {
2699 return filename_mountpoint(dfd, getname(name), path, flags);
2700 }
int
kern_path_mountpoint(int dfd, const char *name, struct path *path,
unsigned int flags)
2705 {
2706 return filename_mountpoint(dfd, getname_kernel(name), path, flags);
2707 }
EXPORT_SYMBOL(kern_path_mountpoint);
int __check_sticky(struct inode *dir, struct inode *inode)
2711 {
2712 kuid_t fsuid = current_fsuid();
2714 if (uid_eq(inode->i_uid, fsuid))
2715 return 0;
2716 if (uid_eq(dir->i_uid, fsuid))
return 0;
2718 return !capable_wrt_inode_uidgid(inode, CAP_FOWNER);
2719 }
EXPORT_SYMBOL(__check_sticky);
/*
* Check whether we can remove a link victim from directory dir, check
* whether the type of victim is right.
* 1. We can't do it if dir is read-only (done in permission())
* 2. We should have write and exec permissions on dir
* 3. We can't remove anything from append-only dir
* 4. We can't do anything with immutable dir (done in permission())
* 5. If the sticky bit on dir is set we should either
* a. be owner of dir, or
* b. be owner of victim, or
* c. have CAP_FOWNER capability
* 6. If the victim is append-only or immutable we can't do antyhing with
* links pointing to it.
* 7. If the victim has an unknown uid or gid we can't change the inode.
* 8. If we were asked to remove a directory and victim isn't one - ENOTDIR.
* 9. If we were asked to remove a non-directory and victim isn't one - EISDIR.
* 10. We can't remove a root or mountpoint.
* 11. We don't allow removal of NFS sillyrenamed files; it's handled by
* nfs_async_unlink().
*/
static int may_delete(struct inode *dir, struct dentry *victim, bool isdir)
2743 {
2744 struct inode *inode = d_backing_inode(victim);
int error;
2747 if (d_is_negative(victim))
2748 return -ENOENT;
2749 BUG_ON(!inode);
2751 BUG_ON(victim->d_parent->d_inode != dir);
audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE);
2754 error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
2755 if (error)
return error;
2757 if (IS_APPEND(dir))
2758 return -EPERM;
2760 if (check_sticky(dir, inode) || IS_APPEND(inode) ||
2761 IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode))
return -EPERM;
2763 if (isdir) {
if (!d_is_dir(victim))
2765 return -ENOTDIR;
2766 if (IS_ROOT(victim))
return -EBUSY;
} else if (d_is_dir(victim))
2769 return -EISDIR;
2770 if (IS_DEADDIR(dir))
return -ENOENT;
if (victim->d_flags & DCACHE_NFSFS_RENAMED)
2773 return -EBUSY;
return 0;
2775 }
/* Check whether we can create an object with dentry child in directory
* dir.
* 1. We can't do it if child already exists (open has special treatment for
* this case, but since we are inlined it's OK)
* 2. We can't do it if dir is read-only (done in permission())
* 3. We can't do it if the fs can't represent the fsuid or fsgid.
* 4. We should have write and exec permissions on dir
* 5. We can't do it if dir is immutable (done in permission())
*/
static inline int may_create(struct inode *dir, struct dentry *child)
{
struct user_namespace *s_user_ns;
audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE);
2790 if (child->d_inode)
2791 return -EEXIST;
2792 if (IS_DEADDIR(dir))
2793 return -ENOENT;
2794 s_user_ns = dir->i_sb->s_user_ns;
2795 if (!kuid_has_mapping(s_user_ns, current_fsuid()) ||
!kgid_has_mapping(s_user_ns, current_fsgid()))
2797 return -EOVERFLOW;
2798 return inode_permission(dir, MAY_WRITE | MAY_EXEC);
}
/*
* p1 and p2 should be directories on the same fs.
*/
struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
2805 {
struct dentry *p;
2808 if (p1 == p2) {
inode_lock_nested(p1->d_inode, I_MUTEX_PARENT);
2810 return NULL;
}
2813 mutex_lock(&p1->d_sb->s_vfs_rename_mutex);
2815 p = d_ancestor(p2, p1);
2816 if (p) {
inode_lock_nested(p2->d_inode, I_MUTEX_PARENT);
inode_lock_nested(p1->d_inode, I_MUTEX_CHILD);
return p;
}
2822 p = d_ancestor(p1, p2);
if (p) {
inode_lock_nested(p1->d_inode, I_MUTEX_PARENT);
inode_lock_nested(p2->d_inode, I_MUTEX_CHILD);
return p;
}
inode_lock_nested(p1->d_inode, I_MUTEX_PARENT);
inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2);
return NULL;
2832 }
EXPORT_SYMBOL(lock_rename);
void unlock_rename(struct dentry *p1, struct dentry *p2)
2836 {
inode_unlock(p1->d_inode);
2838 if (p1 != p2) {
inode_unlock(p2->d_inode);
2840 mutex_unlock(&p1->d_sb->s_vfs_rename_mutex);
}
2842 }
EXPORT_SYMBOL(unlock_rename);
int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
bool want_excl)
2847 {
int error = may_create(dir, dentry);
2849 if (error)
return error;
2852 if (!dir->i_op->create)
2853 return -EACCES; /* shouldn't it be ENOSYS? */
mode &= S_IALLUGO;
2855 mode |= S_IFREG;
2856 error = security_inode_create(dir, dentry, mode);
2857 if (error)
return error;
2859 error = dir->i_op->create(dir, dentry, mode, want_excl);
2860 if (!error)
fsnotify_create(dir, dentry);
return error;
2863 }
EXPORT_SYMBOL(vfs_create);
int vfs_mkobj(struct dentry *dentry, umode_t mode,
int (*f)(struct dentry *, umode_t, void *),
void *arg)
2869 {
2870 struct inode *dir = dentry->d_parent->d_inode;
int error = may_create(dir, dentry);
2872 if (error)
return error;
mode &= S_IALLUGO;
2876 mode |= S_IFREG;
2877 error = security_inode_create(dir, dentry, mode);
2878 if (error)
return error;
2880 error = f(dentry, mode, arg);
2881 if (!error)
fsnotify_create(dir, dentry);
return error;
2884 }
EXPORT_SYMBOL(vfs_mkobj);
bool may_open_dev(const struct path *path)
2888 {
2889 return !(path->mnt->mnt_flags & MNT_NODEV) &&
2890 !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV);
2891 }
static int may_open(const struct path *path, int acc_mode, int flag)
2894 {
struct dentry *dentry = path->dentry;
2896 struct inode *inode = dentry->d_inode;
int error;
2899 if (!inode)
2900 return -ENOENT;
2902 switch (inode->i_mode & S_IFMT) {
case S_IFLNK:
2904 return -ELOOP;
case S_IFDIR:
2906 if (acc_mode & MAY_WRITE)
2907 return -EISDIR;
break;
case S_IFBLK:
case S_IFCHR:
if (!may_open_dev(path))
2912 return -EACCES;
/*FALLTHRU*/
case S_IFIFO:
case S_IFSOCK:
2916 flag &= ~O_TRUNC;
break;
}
2920 error = inode_permission(inode, MAY_OPEN | acc_mode);
2921 if (error)
return error;
/*
* An append-only file must be opened in append mode for writing.
*/
2927 if (IS_APPEND(inode)) {
2928 if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND))
2929 return -EPERM;
2930 if (flag & O_TRUNC)
return -EPERM;
}
/* O_NOATIME can only be set by the owner or superuser */
2935 if (flag & O_NOATIME && !inode_owner_or_capable(inode))
return -EPERM;
return 0;
2939 }
static int handle_truncate(struct file *filp)
{
const struct path *path = &filp->f_path;
2944 struct inode *inode = path->dentry->d_inode;
int error = get_write_access(inode);
if (error)
return error;
/*
* Refuse to truncate files with mandatory locks held on them.
*/
error = locks_verify_locked(filp);
if (!error)
error = security_path_truncate(path);
if (!error) {
2955 error = do_truncate(path->dentry, 0,
ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
filp);
}
put_write_access(inode);
return error;
}
static inline int open_to_namei_flags(int flag)
{
2965 if ((flag & O_ACCMODE) == 3)
2966 flag--;
return flag;
}
static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode)
{
struct user_namespace *s_user_ns;
int error = security_path_mknod(dir, dentry, mode, 0);
if (error)
return error;
2977 s_user_ns = dir->dentry->d_sb->s_user_ns;
2978 if (!kuid_has_mapping(s_user_ns, current_fsuid()) ||
!kgid_has_mapping(s_user_ns, current_fsgid()))
2980 return -EOVERFLOW;
2982 error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC);
2983 if (error)
return error;
2986 return security_inode_create(dir->dentry->d_inode, dentry, mode);
}
/*
* Attempt to atomically look up, create and open a file from a negative
* dentry.
*
* Returns 0 if successful. The file will have been created and attached to
* @file by the filesystem calling finish_open().
*
* Returns 1 if the file was looked up only or didn't need creating. The
* caller will need to perform the open themselves. @path will have been
* updated to point to the new dentry. This may be negative.
*
* Returns an error code otherwise.
*/
static int atomic_open(struct nameidata *nd, struct dentry *dentry,
struct path *path, struct file *file,
const struct open_flags *op,
int open_flag, umode_t mode,
int *opened)
{
struct dentry *const DENTRY_NOT_SET = (void *) -1UL;
3009 struct inode *dir = nd->path.dentry->d_inode;
int error;
3012 if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */
3013 open_flag &= ~O_TRUNC;
if (nd->flags & LOOKUP_DIRECTORY)
3016 open_flag |= O_DIRECTORY;
3018 file->f_path.dentry = DENTRY_NOT_SET;
3019 file->f_path.mnt = nd->path.mnt;
3020 error = dir->i_op->atomic_open(dir, dentry, file,
open_to_namei_flags(open_flag),
mode, opened);
d_lookup_done(dentry);
3024 if (!error) {
/*
* We didn't have the inode before the open, so check open
* permission here.
*/
3029 int acc_mode = op->acc_mode;
3030 if (*opened & FILE_CREATED) {
3031 WARN_ON(!(open_flag & O_CREAT));
fsnotify_create(dir, dentry);
acc_mode = 0;
}
3035 error = may_open(&file->f_path, acc_mode, open_flag);
3036 if (WARN_ON(error > 0))
3037 error = -EINVAL;
3038 } else if (error > 0) {
3039 if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) {
3040 error = -EIO;
} else {
3042 if (file->f_path.dentry) {
3043 dput(dentry);
3044 dentry = file->f_path.dentry;
}
3046 if (*opened & FILE_CREATED)
fsnotify_create(dir, dentry);
3048 if (unlikely(d_is_negative(dentry))) {
error = -ENOENT;
} else {
path->dentry = dentry;
path->mnt = nd->path.mnt;
return 1;
}
}
}
3057 dput(dentry);
return error;
}
/*
* Look up and maybe create and open the last component.
*
* Must be called with i_mutex held on parent.
*
* Returns 0 if the file was successfully atomically created (if necessary) and
* opened. In this case the file will be returned attached to @file.
*
* Returns 1 if the file was not completely opened at this time, though lookups
* and creations will have been performed and the dentry returned in @path will
* be positive upon return if O_CREAT was specified. If O_CREAT wasn't
* specified then a negative dentry may be returned.
*
* An error code is returned otherwise.
*
* FILE_CREATE will be set in @*opened if the dentry was created and will be
* cleared otherwise prior to returning.
*/
static int lookup_open(struct nameidata *nd, struct path *path,
struct file *file,
const struct open_flags *op,
bool got_write, int *opened)
{
3084 struct dentry *dir = nd->path.dentry;
3085 struct inode *dir_inode = dir->d_inode;
3086 int open_flag = op->open_flag;
struct dentry *dentry;
int error, create_error = 0;
3089 umode_t mode = op->mode;
3090 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
3092 if (unlikely(IS_DEADDIR(dir_inode)))
3093 return -ENOENT;
3095 *opened &= ~FILE_CREATED;
3096 dentry = d_lookup(dir, &nd->last);
for (;;) {
3098 if (!dentry) {
3099 dentry = d_alloc_parallel(dir, &nd->last, &wq);
3100 if (IS_ERR(dentry))
3101 return PTR_ERR(dentry);
}
3103 if (d_in_lookup(dentry))
break;
error = d_revalidate(dentry, nd->flags);
3107 if (likely(error > 0))
break;
3109 if (error)
goto out_dput;
3111 d_invalidate(dentry);
3112 dput(dentry);
dentry = NULL;
}
3115 if (dentry->d_inode) {
/* Cached positive dentry: will open in f_op->open */
goto out_no_open;
}
/*
* Checking write permission is tricky, bacuse we don't know if we are
* going to actually need it: O_CREAT opens should work as long as the
* file exists. But checking existence breaks atomicity. The trick is
* to check access and if not granted clear O_CREAT from the flags.
*
* Another problem is returing the "right" error value (e.g. for an
* O_EXCL open we want to return EEXIST not EROFS).
*/
3129 if (open_flag & O_CREAT) {
3130 if (!IS_POSIXACL(dir->d_inode))
3131 mode &= ~current_umask();
3132 if (unlikely(!got_write)) {
3133 create_error = -EROFS;
3134 open_flag &= ~O_CREAT;
3135 if (open_flag & (O_EXCL | O_TRUNC))
goto no_open;
/* No side effects, safe to clear O_CREAT */
} else {
3139 create_error = may_o_create(&nd->path, dentry, mode);
3140 if (create_error) {
3141 open_flag &= ~O_CREAT;
3142 if (open_flag & O_EXCL)
goto no_open;
}
}
3146 } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) &&
unlikely(!got_write)) {
/*
* No O_CREATE -> atomicity not a requirement -> fall
* back to lookup + open
*/
goto no_open;
}
3155 if (dir_inode->i_op->atomic_open) {
error = atomic_open(nd, dentry, path, file, op, open_flag,
mode, opened);
3158 if (unlikely(error == -ENOENT) && create_error)
error = create_error;
return error;
}
no_open:
3164 if (d_in_lookup(dentry)) {
3165 struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry,
nd->flags);
d_lookup_done(dentry);
3168 if (unlikely(res)) {
3169 if (IS_ERR(res)) {
error = PTR_ERR(res);
goto out_dput;
}
3173 dput(dentry);
dentry = res;
}
}
/* Negative dentry, just create the file */
3179 if (!dentry->d_inode && (open_flag & O_CREAT)) {
3180 *opened |= FILE_CREATED;
audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE);
3182 if (!dir_inode->i_op->create) {
3183 error = -EACCES;
goto out_dput;
}
3186 error = dir_inode->i_op->create(dir_inode, dentry, mode,
open_flag & O_EXCL);
3188 if (error)
goto out_dput;
fsnotify_create(dir_inode, dentry);
}
3192 if (unlikely(create_error) && !dentry->d_inode) {
error = create_error;
goto out_dput;
}
out_no_open:
3197 path->dentry = dentry;
3198 path->mnt = nd->path.mnt;
return 1;
out_dput:
3202 dput(dentry);
return error;
}
/*
* Handle the last step of open()
*/
static int do_last(struct nameidata *nd,
struct file *file, const struct open_flags *op,
int *opened)
{
3213 struct dentry *dir = nd->path.dentry;
3214 int open_flag = op->open_flag;
3215 bool will_truncate = (open_flag & O_TRUNC) != 0;
3216 bool got_write = false;
3217 int acc_mode = op->acc_mode;
unsigned seq;
struct inode *inode;
struct path path;
int error;
3223 nd->flags &= ~LOOKUP_PARENT;
3224 nd->flags |= op->intent;
3226 if (nd->last_type != LAST_NORM) {
error = handle_dots(nd, nd->last_type);
if (unlikely(error))
return error;
goto finish_open;
}
3233 if (!(open_flag & O_CREAT)) {
3234 if (nd->last.name[nd->last.len])
3235 nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
/* we _can_ be in RCU mode here */
3237 error = lookup_fast(nd, &path, &inode, &seq);
3238 if (likely(error > 0))
goto finish_lookup;
3241 if (error < 0)
return error;
3244 BUG_ON(nd->inode != dir->d_inode);
3245 BUG_ON(nd->flags & LOOKUP_RCU);
} else {
/* create side of things */
/*
* This will *only* deal with leaving RCU mode - LOOKUP_JUMPED
* has been cleared when we got to the last component we are
* about to look up
*/
3253 error = complete_walk(nd);
3254 if (error)
return error;
audit_inode(nd->name, dir, LOOKUP_PARENT);
/* trailing slashes? */
3259 if (unlikely(nd->last.name[nd->last.len]))
return -EISDIR;
}
3263 if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) {
3264 error = mnt_want_write(nd->path.mnt);
3265 if (!error)
got_write = true;
/*
* do _not_ fail yet - we might not need that or fail with
* a different error; let lookup_open() decide; we'll be
* dropping this one anyway.
*/
}
if (open_flag & O_CREAT)
inode_lock(dir->d_inode);
else
inode_lock_shared(dir->d_inode);
error = lookup_open(nd, &path, file, op, got_write, opened);
3278 if (open_flag & O_CREAT)
inode_unlock(dir->d_inode);
else
inode_unlock_shared(dir->d_inode);
3283 if (error <= 0) {
3284 if (error)
goto out;
3287 if ((*opened & FILE_CREATED) ||
3288 !S_ISREG(file_inode(file)->i_mode))
will_truncate = false;
audit_inode(nd->name, file->f_path.dentry, 0);
goto opened;
}
3295 if (*opened & FILE_CREATED) {
/* Don't check for write permission, don't truncate */
3297 open_flag &= ~O_TRUNC;
3298 will_truncate = false;
3299 acc_mode = 0;
path_to_nameidata(&path, nd);
goto finish_open_created;
}
/*
* If atomic_open() acquired write access it is dropped now due to
* possible mount and symlink following (this might be optimized away if
* necessary...)
*/
3309 if (got_write) {
3310 mnt_drop_write(nd->path.mnt);
got_write = false;
}
3314 error = follow_managed(&path, nd);
3315 if (unlikely(error < 0))
return error;
3318 if (unlikely(d_is_negative(path.dentry))) {
path_to_nameidata(&path, nd);
return -ENOENT;
}
/*
* create/update audit record if it already exists.
*/
audit_inode(nd->name, path.dentry, 0);
3328 if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) {
path_to_nameidata(&path, nd);
3330 return -EEXIST;
}
3333 seq = 0; /* out of RCU mode, so the value doesn't matter */
3334 inode = d_backing_inode(path.dentry);
finish_lookup:
error = step_into(nd, &path, 0, inode, seq);
3337 if (unlikely(error))
return error;
finish_open:
/* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
3341 error = complete_walk(nd);
3342 if (error)
return error;
3344 audit_inode(nd->name, nd->path.dentry, 0);
3345 error = -EISDIR;
3346 if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry))
goto out;
3348 error = -ENOTDIR;
3349 if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry))
goto out;
3351 if (!d_is_reg(nd->path.dentry))
3352 will_truncate = false;
3354 if (will_truncate) {
3355 error = mnt_want_write(nd->path.mnt);
3356 if (error)
goto out;
3358 got_write = true;
}
finish_open_created:
3361 error = may_open(&nd->path, acc_mode, open_flag);
3362 if (error)
goto out;
3364 BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
3365 error = vfs_open(&nd->path, file, current_cred());
3366 if (error)
goto out;
3368 *opened |= FILE_OPENED;
opened:
error = ima_file_check(file, op->acc_mode, *opened);
3371 if (!error && will_truncate)
error = handle_truncate(file);
out:
3374 if (unlikely(error) && (*opened & FILE_OPENED))
3375 fput(file);
3376 if (unlikely(error > 0)) {
3377 WARN_ON(1);
3378 error = -EINVAL;
}
3380 if (got_write)
3381 mnt_drop_write(nd->path.mnt);
return error;
}
struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag)
3386 {
3387 struct dentry *child = NULL;
3388 struct inode *dir = dentry->d_inode;
struct inode *inode;
int error;
/* we want directory to be writable */
3393 error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
3394 if (error)
goto out_err;
error = -EOPNOTSUPP;
3397 if (!dir->i_op->tmpfile)
goto out_err;
error = -ENOMEM;
3400 child = d_alloc(dentry, &slash_name);
3401 if (unlikely(!child))
goto out_err;
3403 error = dir->i_op->tmpfile(dir, child, mode);
3404 if (error)
goto out_err;
error = -ENOENT;
3407 inode = child->d_inode;
3408 if (unlikely(!inode))
goto out_err;
3410 if (!(open_flag & O_EXCL)) {
spin_lock(&inode->i_lock);
3412 inode->i_state |= I_LINKABLE;
spin_unlock(&inode->i_lock);
}
return child;
3417 out_err:
3418 dput(child);
return ERR_PTR(error);
3420 }
EXPORT_SYMBOL(vfs_tmpfile);
static int do_tmpfile(struct nameidata *nd, unsigned flags,
const struct open_flags *op,
struct file *file, int *opened)
{
struct dentry *child;
struct path path;
3429 int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path);
3430 if (unlikely(error))
return error;
3432 error = mnt_want_write(path.mnt);
3433 if (unlikely(error))
goto out;
3435 child = vfs_tmpfile(path.dentry, op->mode, op->open_flag);
3436 error = PTR_ERR(child);
3437 if (IS_ERR(child))
goto out2;
3439 dput(path.dentry);
3440 path.dentry = child;
audit_inode(nd->name, child, 0);
/* Don't check for other permissions, the inode was just created */
3443 error = may_open(&path, 0, op->open_flag);
3444 if (error)
goto out2;
3446 file->f_path.mnt = path.mnt;
3447 error = finish_open(file, child, NULL, opened);
if (error)
goto out2;
out2:
3451 mnt_drop_write(path.mnt);
out:
path_put(&path);
return error;
}
static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file)
{
struct path path;
3460 int error = path_lookupat(nd, flags, &path);
3461 if (!error) {
audit_inode(nd->name, path.dentry, 0);
3463 error = vfs_open(&path, file, current_cred());
path_put(&path);
}
return error;
}
static struct file *path_openat(struct nameidata *nd,
const struct open_flags *op, unsigned flags)
3471 {
const char *s;
struct file *file;
3474 int opened = 0;
int error;
3477 file = get_empty_filp();
3478 if (IS_ERR(file))
return file;
3481 file->f_flags = op->open_flag;
3483 if (unlikely(file->f_flags & __O_TMPFILE)) {
error = do_tmpfile(nd, flags, op, file, &opened);
3485 goto out2;
}
3488 if (unlikely(file->f_flags & O_PATH)) {
error = do_o_path(nd, flags, file);
3490 if (!error)
opened |= FILE_OPENED;
goto out2;
}
3495 s = path_init(nd, flags);
3496 if (IS_ERR(s)) {
3497 put_filp(file);
3498 return ERR_CAST(s);
}
3500 while (!(error = link_path_walk(s, nd)) &&
(error = do_last(nd, file, op, &opened)) > 0) {
3502 nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
3503 s = trailing_symlink(nd);
3504 if (IS_ERR(s)) {
3505 error = PTR_ERR(s);
break;
}
}
3509 terminate_walk(nd);
out2:
3511 if (!(opened & FILE_OPENED)) {
3512 BUG_ON(!error);
3513 put_filp(file);
}
3515 if (unlikely(error)) {
3516 if (error == -EOPENSTALE) {
3517 if (flags & LOOKUP_RCU)
error = -ECHILD;
else
error = -ESTALE;
}
file = ERR_PTR(error);
}
return file;
3525 }
struct file *do_filp_open(int dfd, struct filename *pathname,
const struct open_flags *op)
3529 {
struct nameidata nd;
3531 int flags = op->lookup_flags;
struct file *filp;
set_nameidata(&nd, dfd, pathname);
3535 filp = path_openat(&nd, op, flags | LOOKUP_RCU);
3536 if (unlikely(filp == ERR_PTR(-ECHILD)))
3537 filp = path_openat(&nd, op, flags);
3538 if (unlikely(filp == ERR_PTR(-ESTALE)))
3539 filp = path_openat(&nd, op, flags | LOOKUP_REVAL);
3540 restore_nameidata();
return filp;
3542 }
struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
const char *name, const struct open_flags *op)
3546 {
struct nameidata nd;
struct file *file;
struct filename *filename;
3550 int flags = op->lookup_flags | LOOKUP_ROOT;
3552 nd.root.mnt = mnt;
3553 nd.root.dentry = dentry;
3555 if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN)
3556 return ERR_PTR(-ELOOP);
3558 filename = getname_kernel(name);
3559 if (IS_ERR(filename))
3560 return ERR_CAST(filename);
set_nameidata(&nd, -1, filename);
3563 file = path_openat(&nd, op, flags | LOOKUP_RCU);
3564 if (unlikely(file == ERR_PTR(-ECHILD)))
3565 file = path_openat(&nd, op, flags);
3566 if (unlikely(file == ERR_PTR(-ESTALE)))
3567 file = path_openat(&nd, op, flags | LOOKUP_REVAL);
3568 restore_nameidata();
3569 putname(filename);
return file;
3571 }
static struct dentry *filename_create(int dfd, struct filename *name,
struct path *path, unsigned int lookup_flags)
3575 {
3576 struct dentry *dentry = ERR_PTR(-EEXIST);
struct qstr last;
int type;
int err2;
int error;
bool is_dir = (lookup_flags & LOOKUP_DIRECTORY);
/*
* Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any
* other flags passed in are ignored!
*/
3587 lookup_flags &= LOOKUP_REVAL;
3589 name = filename_parentat(dfd, name, lookup_flags, path, &last, &type);
3590 if (IS_ERR(name))
3591 return ERR_CAST(name);
/*
* Yucky last component or no last component at all?
* (foo/., foo/.., /////)
*/
3597 if (unlikely(type != LAST_NORM))
goto out;
/* don't fail immediately if it's r/o, at least try to report other errors */
3601 err2 = mnt_want_write(path->mnt);
/*
* Do the final lookup.
*/
3605 lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL;
3606 inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT);
3607 dentry = __lookup_hash(&last, path->dentry, lookup_flags);
3608 if (IS_ERR(dentry))
goto unlock;
error = -EEXIST;
3612 if (d_is_positive(dentry))
goto fail;
/*
* Special case - lookup gave negative, but... we had foo/bar/
* From the vfs_mknod() POV we just have a negative dentry -
* all is fine. Let's be bastards - you had / on the end, you've
* been asking for (non-existent) directory. -ENOENT for you.
*/
3621 if (unlikely(!is_dir && last.name[last.len])) {
error = -ENOENT;
goto fail;
}
3625 if (unlikely(err2)) {
error = err2;
goto fail;
}
putname(name);
return dentry;
3631 fail:
3632 dput(dentry);
3633 dentry = ERR_PTR(error);
unlock:
3635 inode_unlock(path->dentry->d_inode);
3636 if (!err2)
3637 mnt_drop_write(path->mnt);
out:
path_put(path);
3640 putname(name);
return dentry;
3642 }
struct dentry *kern_path_create(int dfd, const char *pathname,
struct path *path, unsigned int lookup_flags)
3646 {
3647 return filename_create(dfd, getname_kernel(pathname),
path, lookup_flags);
3649 }
EXPORT_SYMBOL(kern_path_create);
void done_path_create(struct path *path, struct dentry *dentry)
3653 {
3654 dput(dentry);
3655 inode_unlock(path->dentry->d_inode);
3656 mnt_drop_write(path->mnt);
path_put(path);
3658 }
EXPORT_SYMBOL(done_path_create);
inline struct dentry *user_path_create(int dfd, const char __user *pathname,
struct path *path, unsigned int lookup_flags)
3663 {
3664 return filename_create(dfd, getname(pathname), path, lookup_flags);
3665 }
EXPORT_SYMBOL(user_path_create);
int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
3669 {
int error = may_create(dir, dentry);
3672 if (error)
return error;
3675 if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
3676 return -EPERM;
3678 if (!dir->i_op->mknod)
return -EPERM;
error = devcgroup_inode_mknod(mode, dev);
3682 if (error)
return error;
3685 error = security_inode_mknod(dir, dentry, mode, dev);
3686 if (error)
return error;
3689 error = dir->i_op->mknod(dir, dentry, mode, dev);
3690 if (!error)
fsnotify_create(dir, dentry);
return error;
3693 }
EXPORT_SYMBOL(vfs_mknod);
static int may_mknod(umode_t mode)
{
3698 switch (mode & S_IFMT) {
case S_IFREG:
case S_IFCHR:
case S_IFBLK:
case S_IFIFO:
case S_IFSOCK:
case 0: /* zero mode translates to S_IFREG */
return 0;
case S_IFDIR:
return -EPERM;
default:
return -EINVAL;
}
}
long do_mknodat(int dfd, const char __user *filename, umode_t mode,
unsigned int dev)
3715 {
struct dentry *dentry;
struct path path;
int error;
3719 unsigned int lookup_flags = 0;
error = may_mknod(mode);
if (error)
return error;
retry:
dentry = user_path_create(dfd, filename, &path, lookup_flags);
3726 if (IS_ERR(dentry))
return PTR_ERR(dentry);
3729 if (!IS_POSIXACL(path.dentry->d_inode))
3730 mode &= ~current_umask();
3731 error = security_path_mknod(&path, dentry, mode, dev);
if (error)
goto out;
3734 switch (mode & S_IFMT) {
case 0: case S_IFREG:
3736 error = vfs_create(path.dentry->d_inode,dentry,mode,true);
if (!error)
ima_post_path_mknod(dentry);
break;
case S_IFCHR: case S_IFBLK:
3741 error = vfs_mknod(path.dentry->d_inode,dentry,mode,
new_decode_dev(dev));
break;
case S_IFIFO: case S_IFSOCK:
3745 error = vfs_mknod(path.dentry->d_inode,dentry,mode,0);
break;
}
out:
3749 done_path_create(&path, dentry);
3750 if (retry_estale(error, lookup_flags)) {
3751 lookup_flags |= LOOKUP_REVAL;
goto retry;
}
return error;
3755 }
3757 SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode,
unsigned int, dev)
{
3760 return do_mknodat(dfd, filename, mode, dev);
}
3763 SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev)
{
3765 return do_mknodat(AT_FDCWD, filename, mode, dev);
}
int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
3769 {
int error = may_create(dir, dentry);
3771 unsigned max_links = dir->i_sb->s_max_links;
3773 if (error)
return error;
3776 if (!dir->i_op->mkdir)
3777 return -EPERM;
mode &= (S_IRWXUGO|S_ISVTX);
3780 error = security_inode_mkdir(dir, dentry, mode);
3781 if (error)
return error;
3784 if (max_links && dir->i_nlink >= max_links)
3785 return -EMLINK;
3787 error = dir->i_op->mkdir(dir, dentry, mode);
3788 if (!error)
fsnotify_mkdir(dir, dentry);
return error;
3791 }
EXPORT_SYMBOL(vfs_mkdir);
long do_mkdirat(int dfd, const char __user *pathname, umode_t mode)
3795 {
struct dentry *dentry;
struct path path;
int error;
3799 unsigned int lookup_flags = LOOKUP_DIRECTORY;
retry:
dentry = user_path_create(dfd, pathname, &path, lookup_flags);
3803 if (IS_ERR(dentry))
return PTR_ERR(dentry);
3806 if (!IS_POSIXACL(path.dentry->d_inode))
3807 mode &= ~current_umask();
3808 error = security_path_mkdir(&path, dentry, mode);
if (!error)
3810 error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
3811 done_path_create(&path, dentry);
3812 if (retry_estale(error, lookup_flags)) {
3813 lookup_flags |= LOOKUP_REVAL;
goto retry;
}
return error;
3817 }
3819 SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode)
{
3821 return do_mkdirat(dfd, pathname, mode);
}
3824 SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode)
{
3826 return do_mkdirat(AT_FDCWD, pathname, mode);
}
int vfs_rmdir(struct inode *dir, struct dentry *dentry)
3830 {
3831 int error = may_delete(dir, dentry, 1);
3833 if (error)
return error;
3836 if (!dir->i_op->rmdir)
3837 return -EPERM;
dget(dentry);
inode_lock(dentry->d_inode);
3842 error = -EBUSY;
3843 if (is_local_mountpoint(dentry))
goto out;
3846 error = security_inode_rmdir(dir, dentry);
3847 if (error)
goto out;
3850 shrink_dcache_parent(dentry);
3851 error = dir->i_op->rmdir(dir, dentry);
3852 if (error)
goto out;
3855 dentry->d_inode->i_flags |= S_DEAD;
dont_mount(dentry);
detach_mounts(dentry);
out:
inode_unlock(dentry->d_inode);
3861 dput(dentry);
if (!error)
3863 d_delete(dentry);
return error;
3865 }
EXPORT_SYMBOL(vfs_rmdir);
long do_rmdir(int dfd, const char __user *pathname)
3869 {
int error = 0;
struct filename *name;
struct dentry *dentry;
struct path path;
struct qstr last;
int type;
3876 unsigned int lookup_flags = 0;
retry:
3878 name = filename_parentat(dfd, getname(pathname), lookup_flags,
&path, &last, &type);
3880 if (IS_ERR(name))
3881 return PTR_ERR(name);
3883 switch (type) {
case LAST_DOTDOT:
error = -ENOTEMPTY;
goto exit1;
case LAST_DOT:
error = -EINVAL;
goto exit1;
case LAST_ROOT:
error = -EBUSY;
goto exit1;
}
3895 error = mnt_want_write(path.mnt);
3896 if (error)
goto exit1;
3899 inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT);
3900 dentry = __lookup_hash(&last, path.dentry, lookup_flags);
error = PTR_ERR(dentry);
3902 if (IS_ERR(dentry))
goto exit2;
3904 if (!dentry->d_inode) {
error = -ENOENT;
goto exit3;
}
error = security_path_rmdir(&path, dentry);
if (error)
goto exit3;
3911 error = vfs_rmdir(path.dentry->d_inode, dentry);
exit3:
3913 dput(dentry);
exit2:
3915 inode_unlock(path.dentry->d_inode);
3916 mnt_drop_write(path.mnt);
exit1:
path_put(&path);
3919 putname(name);
if (retry_estale(error, lookup_flags)) {
3921 lookup_flags |= LOOKUP_REVAL;
goto retry;
}
return error;
3925 }
3927 SYSCALL_DEFINE1(rmdir, const char __user *, pathname)
{
3929 return do_rmdir(AT_FDCWD, pathname);
}
/**
* vfs_unlink - unlink a filesystem object
* @dir: parent directory
* @dentry: victim
* @delegated_inode: returns victim inode, if the inode is delegated.
*
* The caller must hold dir->i_mutex.
*
* If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and
* return a reference to the inode in delegated_inode. The caller
* should then break the delegation on that inode and retry. Because
* breaking a delegation may take a long time, the caller should drop
* dir->i_mutex before doing so.
*
* Alternatively, a caller may pass NULL for delegated_inode. This may
* be appropriate for callers that expect the underlying filesystem not
* to be NFS exported.
*/
int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode)
3951 {
3952 struct inode *target = dentry->d_inode;
3953 int error = may_delete(dir, dentry, 0);
3955 if (error)
return error;
3958 if (!dir->i_op->unlink)
3959 return -EPERM;
inode_lock(target);
3962 if (is_local_mountpoint(dentry))
3963 error = -EBUSY;
else {
3965 error = security_inode_unlink(dir, dentry);
3966 if (!error) {
error = try_break_deleg(target, delegated_inode);
3968 if (error)
goto out;
3970 error = dir->i_op->unlink(dir, dentry);
3971 if (!error) {
dont_mount(dentry);
detach_mounts(dentry);
}
}
}
out:
inode_unlock(target);
/* We don't d_delete() NFS sillyrenamed files--they still exist. */
3981 if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
fsnotify_link_count(target);
3983 d_delete(dentry);
}
return error;
3987 }
EXPORT_SYMBOL(vfs_unlink);
/*
* Make sure that the actual truncation of the file will occur outside its
* directory's i_mutex. Truncate can take a long time if there is a lot of
* writeout happening, and we don't want to prevent access to the directory
* while waiting on the I/O.
*/
long do_unlinkat(int dfd, struct filename *name)
3997 {
int error;
struct dentry *dentry;
struct path path;
struct qstr last;
int type;
struct inode *inode = NULL;
4004 struct inode *delegated_inode = NULL;
4005 unsigned int lookup_flags = 0;
retry:
4007 name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type);
4008 if (IS_ERR(name))
4009 return PTR_ERR(name);
error = -EISDIR;
4012 if (type != LAST_NORM)
goto exit1;
4015 error = mnt_want_write(path.mnt);
4016 if (error)
goto exit1;
retry_deleg:
4019 inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT);
4020 dentry = __lookup_hash(&last, path.dentry, lookup_flags);
4021 error = PTR_ERR(dentry);
4022 if (!IS_ERR(dentry)) {
/* Why not before? Because we want correct error value */
4024 if (last.name[last.len])
goto slashes;
4026 inode = dentry->d_inode;
4027 if (d_is_negative(dentry))
goto slashes;
4029 ihold(inode);
error = security_path_unlink(&path, dentry);
if (error)
goto exit2;
4033 error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode);
exit2:
4035 dput(dentry);
}
4037 inode_unlock(path.dentry->d_inode);
4038 if (inode)
4039 iput(inode); /* truncate the inode here */
inode = NULL;
4041 if (delegated_inode) {
error = break_deleg_wait(&delegated_inode);
4043 if (!error)
goto retry_deleg;
}
4046 mnt_drop_write(path.mnt);
exit1:
path_put(&path);
4049 if (retry_estale(error, lookup_flags)) {
4050 lookup_flags |= LOOKUP_REVAL;
inode = NULL;
goto retry;
}
4054 putname(name);
return error;
slashes:
4058 if (d_is_negative(dentry))
4059 error = -ENOENT;
else if (d_is_dir(dentry))
4061 error = -EISDIR;
else
4063 error = -ENOTDIR;
goto exit2;
4065 }
4067 SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag)
{
4069 if ((flag & ~AT_REMOVEDIR) != 0)
return -EINVAL;
4072 if (flag & AT_REMOVEDIR)
4073 return do_rmdir(dfd, pathname);
4075 return do_unlinkat(dfd, getname(pathname));
}
4078 SYSCALL_DEFINE1(unlink, const char __user *, pathname)
{
4080 return do_unlinkat(AT_FDCWD, getname(pathname));
}
int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
4084 {
int error = may_create(dir, dentry);
4087 if (error)
return error;
4090 if (!dir->i_op->symlink)
4091 return -EPERM;
4093 error = security_inode_symlink(dir, dentry, oldname);
4094 if (error)
return error;
4097 error = dir->i_op->symlink(dir, dentry, oldname);
4098 if (!error)
fsnotify_create(dir, dentry);
return error;
4101 }
EXPORT_SYMBOL(vfs_symlink);
long do_symlinkat(const char __user *oldname, int newdfd,
const char __user *newname)
4106 {
int error;
struct filename *from;
struct dentry *dentry;
struct path path;
unsigned int lookup_flags = 0;
from = getname(oldname);
4114 if (IS_ERR(from))
return PTR_ERR(from);
retry:
dentry = user_path_create(newdfd, newname, &path, lookup_flags);
4118 error = PTR_ERR(dentry);
4119 if (IS_ERR(dentry))
goto out_putname;
error = security_path_symlink(&path, dentry, from->name);
if (!error)
4124 error = vfs_symlink(path.dentry->d_inode, dentry, from->name);
4125 done_path_create(&path, dentry);
if (retry_estale(error, lookup_flags)) {
4127 lookup_flags |= LOOKUP_REVAL;
goto retry;
}
out_putname:
4131 putname(from);
4132 return error;
4133 }
4135 SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
int, newdfd, const char __user *, newname)
{
4138 return do_symlinkat(oldname, newdfd, newname);
}
4141 SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname)
{
4143 return do_symlinkat(oldname, AT_FDCWD, newname);
}
/**
* vfs_link - create a new link
* @old_dentry: object to be linked
* @dir: new parent
* @new_dentry: where to create the new link
* @delegated_inode: returns inode needing a delegation break
*
* The caller must hold dir->i_mutex
*
* If vfs_link discovers a delegation on the to-be-linked file in need
* of breaking, it will return -EWOULDBLOCK and return a reference to the
* inode in delegated_inode. The caller should then break the delegation
* and retry. Because breaking a delegation may take a long time, the
* caller should drop the i_mutex before doing so.
*
* Alternatively, a caller may pass NULL for delegated_inode. This may
* be appropriate for callers that expect the underlying filesystem not
* to be NFS exported.
*/
int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode)
4166 {
4167 struct inode *inode = old_dentry->d_inode;
4168 unsigned max_links = dir->i_sb->s_max_links;
int error;
4171 if (!inode)
return -ENOENT;
error = may_create(dir, new_dentry);
4175 if (error)
return error;
4178 if (dir->i_sb != inode->i_sb)
4179 return -EXDEV;
/*
* A link to an append-only or immutable file cannot be created.
*/
4184 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
4185 return -EPERM;
/*
* Updating the link count will likely cause i_uid and i_gid to
* be writen back improperly if their true value is unknown to
* the vfs.
*/
if (HAS_UNMAPPED_ID(inode))
return -EPERM;
4193 if (!dir->i_op->link)
return -EPERM;
4195 if (S_ISDIR(inode->i_mode))
return -EPERM;
4198 error = security_inode_link(old_dentry, dir, new_dentry);
4199 if (error)
return error;
inode_lock(inode);
/* Make sure we don't allow creating hardlink to an unlinked file */
4204 if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE))
4205 error = -ENOENT;
4206 else if (max_links && inode->i_nlink >= max_links)
4207 error = -EMLINK;
else {
error = try_break_deleg(inode, delegated_inode);
4210 if (!error)
4211 error = dir->i_op->link(old_dentry, dir, new_dentry);
}
4214 if (!error && (inode->i_state & I_LINKABLE)) {
spin_lock(&inode->i_lock);
4216 inode->i_state &= ~I_LINKABLE;
spin_unlock(&inode->i_lock);
}
inode_unlock(inode);
if (!error)
fsnotify_link(dir, inode, new_dentry);
return error;
4223 }
EXPORT_SYMBOL(vfs_link);
/*
* Hardlinks are often used in delicate situations. We avoid
* security-related surprises by not following symlinks on the
* newname. --KAB
*
* We don't follow them on the oldname either to be compatible
* with linux 2.0, and to avoid hard-linking to directories
* and other special files. --ADM
*/
int do_linkat(int olddfd, const char __user *oldname, int newdfd,
const char __user *newname, int flags)
4237 {
struct dentry *new_dentry;
struct path old_path, new_path;
4240 struct inode *delegated_inode = NULL;
int how = 0;
int error;
4244 if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0)
4245 return -EINVAL;
/*
* To use null names we require CAP_DAC_READ_SEARCH
* This ensures that not everyone will be able to create
* handlink using the passed filedescriptor.
*/
4251 if (flags & AT_EMPTY_PATH) {
4252 if (!capable(CAP_DAC_READ_SEARCH))
4253 return -ENOENT;
4254 how = LOOKUP_EMPTY;
}
if (flags & AT_SYMLINK_FOLLOW)
4258 how |= LOOKUP_FOLLOW;
retry:
error = user_path_at(olddfd, oldname, how, &old_path);
4261 if (error)
return error;
4264 new_dentry = user_path_create(newdfd, newname, &new_path,
(how & LOOKUP_REVAL));
error = PTR_ERR(new_dentry);
4267 if (IS_ERR(new_dentry))
goto out;
4270 error = -EXDEV;
4271 if (old_path.mnt != new_path.mnt)
goto out_dput;
error = may_linkat(&old_path);
if (unlikely(error))
goto out_dput;
error = security_path_link(old_path.dentry, &new_path, new_dentry);
if (error)
goto out_dput;
4279 error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode);
out_dput:
4281 done_path_create(&new_path, new_dentry);
4282 if (delegated_inode) {
error = break_deleg_wait(&delegated_inode);
4284 if (!error) {
path_put(&old_path);
goto retry;
}
}
if (retry_estale(error, how)) {
path_put(&old_path);
4291 how |= LOOKUP_REVAL;
4292 goto retry;
}
out:
path_put(&old_path);
4297 return error;
4298 }
4300 SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
int, newdfd, const char __user *, newname, int, flags)
{
4303 return do_linkat(olddfd, oldname, newdfd, newname, flags);
}
4306 SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname)
{
4308 return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
}
/**
* vfs_rename - rename a filesystem object
* @old_dir: parent of source
* @old_dentry: source
* @new_dir: parent of destination
* @new_dentry: destination
* @delegated_inode: returns an inode needing a delegation break
* @flags: rename flags
*
* The caller must hold multiple mutexes--see lock_rename()).
*
* If vfs_rename discovers a delegation in need of breaking at either
* the source or destination, it will return -EWOULDBLOCK and return a
* reference to the inode in delegated_inode. The caller should then
* break the delegation and retry. Because breaking a delegation may
* take a long time, the caller should drop all locks before doing
* so.
*
* Alternatively, a caller may pass NULL for delegated_inode. This may
* be appropriate for callers that expect the underlying filesystem not
* to be NFS exported.
*
* The worst of all namespace operations - renaming directory. "Perverted"
* doesn't even start to describe it. Somebody in UCB had a heck of a trip...
* Problems:
*
* a) we can get into loop creation.
* b) race potential - two innocent renames can create a loop together.
* That's where 4.4 screws up. Current fix: serialization on
* sb->s_vfs_rename_mutex. We might be more accurate, but that's another
* story.
* c) we have to lock _four_ objects - parents and victim (if it exists),
* and source (if it is not a directory).
* And that - after we got ->i_mutex on parents (until then we don't know
* whether the target exists). Solution: try to be smart with locking
* order for inodes. We rely on the fact that tree topology may change
* only under ->s_vfs_rename_mutex _and_ that parent of the object we
* move will be locked. Thus we can rank directories by the tree
* (ancestors first) and rank all non-directories after them.
* That works since everybody except rename does "lock parent, lookup,
* lock child" and rename is under ->s_vfs_rename_mutex.
* HOWEVER, it relies on the assumption that any object with ->lookup()
* has no more than 1 dentry. If "hybrid" objects will ever appear,
* we'd better make sure that there's no link(2) for them.
* d) conversion from fhandle to dentry may come in the wrong moment - when
* we are removing the target. Solution: we will have to grab ->i_mutex
* in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
* ->i_mutex on parents, which works but leads to some truly excessive
* locking].
*/
int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry,
struct inode **delegated_inode, unsigned int flags)
4364 {
int error;
bool is_dir = d_is_dir(old_dentry);
4367 struct inode *source = old_dentry->d_inode;
4368 struct inode *target = new_dentry->d_inode;
4369 bool new_is_dir = false;
4370 unsigned max_links = new_dir->i_sb->s_max_links;
struct name_snapshot old_name;
4373 if (source == target)
4374 return 0;
4376 error = may_delete(old_dir, old_dentry, is_dir);
4377 if (error)
return error;
4380 if (!target) {
error = may_create(new_dir, new_dentry);
} else {
new_is_dir = d_is_dir(new_dentry);
4385 if (!(flags & RENAME_EXCHANGE))
4386 error = may_delete(new_dir, new_dentry, is_dir);
else
4388 error = may_delete(new_dir, new_dentry, new_is_dir);
}
4390 if (error)
return error;
4393 if (!old_dir->i_op->rename)
4394 return -EPERM;
/*
* If we are going to change the parent - check write permissions,
* we'll need to flip '..'.
*/
4400 if (new_dir != old_dir) {
4401 if (is_dir) {
4402 error = inode_permission(source, MAY_WRITE);
4403 if (error)
return error;
}
4406 if ((flags & RENAME_EXCHANGE) && new_is_dir) {
4407 error = inode_permission(target, MAY_WRITE);
4408 if (error)
return error;
}
}
4413 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry,
flags);
4415 if (error)
return error;
4418 take_dentry_name_snapshot(&old_name, old_dentry);
dget(new_dentry);
4420 if (!is_dir || (flags & RENAME_EXCHANGE))
4421 lock_two_nondirectories(source, target);
4422 else if (target)
inode_lock(target);
4425 error = -EBUSY;
4426 if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry))
goto out;
4429 if (max_links && new_dir != old_dir) {
4430 error = -EMLINK;
4431 if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links)
goto out;
4433 if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir &&
old_dir->i_nlink >= max_links)
goto out;
}
4437 if (is_dir && !(flags & RENAME_EXCHANGE) && target)
4438 shrink_dcache_parent(new_dentry);
if (!is_dir) {
error = try_break_deleg(source, delegated_inode);
4441 if (error)
goto out;
}
4444 if (target && !new_is_dir) {
error = try_break_deleg(target, delegated_inode);
4446 if (error)
goto out;
}
4449 error = old_dir->i_op->rename(old_dir, old_dentry,
new_dir, new_dentry, flags);
4451 if (error)
goto out;
4454 if (!(flags & RENAME_EXCHANGE) && target) {
4455 if (is_dir)
4456 target->i_flags |= S_DEAD;
dont_mount(new_dentry);
detach_mounts(new_dentry);
}
4460 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) {
if (!(flags & RENAME_EXCHANGE))
4462 d_move(old_dentry, new_dentry);
else
4464 d_exchange(old_dentry, new_dentry);
}
out:
4467 if (!is_dir || (flags & RENAME_EXCHANGE))
4468 unlock_two_nondirectories(source, target);
4469 else if (target)
inode_unlock(target);
4471 dput(new_dentry);
if (!error) {
4473 fsnotify_move(old_dir, new_dir, old_name.name, is_dir,
4474 !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry);
4475 if (flags & RENAME_EXCHANGE) {
4476 fsnotify_move(new_dir, old_dir, old_dentry->d_name.name,
new_is_dir, NULL, new_dentry);
}
}
4480 release_dentry_name_snapshot(&old_name);
4482 return error;
4483 }
EXPORT_SYMBOL(vfs_rename);
static int do_renameat2(int olddfd, const char __user *oldname, int newdfd,
const char __user *newname, unsigned int flags)
4488 {
struct dentry *old_dentry, *new_dentry;
struct dentry *trap;
struct path old_path, new_path;
struct qstr old_last, new_last;
int old_type, new_type;
4494 struct inode *delegated_inode = NULL;
struct filename *from;
struct filename *to;
4497 unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET;
bool should_retry = false;
int error;
4501 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
4502 return -EINVAL;
4504 if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) &&
(flags & RENAME_EXCHANGE))
return -EINVAL;
4508 if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD))
4509 return -EPERM;
4511 if (flags & RENAME_EXCHANGE)
target_flags = 0;
4514 retry:
4515 from = filename_parentat(olddfd, getname(oldname), lookup_flags,
&old_path, &old_last, &old_type);
4517 if (IS_ERR(from)) {
4518 error = PTR_ERR(from);
4519 goto exit;
}
4522 to = filename_parentat(newdfd, getname(newname), lookup_flags,
&new_path, &new_last, &new_type);
4524 if (IS_ERR(to)) {
4525 error = PTR_ERR(to);
goto exit1;
}
4529 error = -EXDEV;
4530 if (old_path.mnt != new_path.mnt)
goto exit2;
4533 error = -EBUSY;
4534 if (old_type != LAST_NORM)
goto exit2;
4537 if (flags & RENAME_NOREPLACE)
4538 error = -EEXIST;
4539 if (new_type != LAST_NORM)
goto exit2;
4542 error = mnt_want_write(old_path.mnt);
4543 if (error)
goto exit2;
retry_deleg:
4547 trap = lock_rename(new_path.dentry, old_path.dentry);
4549 old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags);
4550 error = PTR_ERR(old_dentry);
4551 if (IS_ERR(old_dentry))
goto exit3;
/* source must exist */
4554 error = -ENOENT;
4555 if (d_is_negative(old_dentry))
goto exit4;
4557 new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags);
4558 error = PTR_ERR(new_dentry);
4559 if (IS_ERR(new_dentry))
goto exit4;
4561 error = -EEXIST;
4562 if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry))
goto exit5;
4564 if (flags & RENAME_EXCHANGE) {
4565 error = -ENOENT;
4566 if (d_is_negative(new_dentry))
goto exit5;
if (!d_is_dir(new_dentry)) {
error = -ENOTDIR;
4571 if (new_last.name[new_last.len])
goto exit5;
}
}
/* unless the source is a directory trailing slashes give -ENOTDIR */
if (!d_is_dir(old_dentry)) {
4577 error = -ENOTDIR;
4578 if (old_last.name[old_last.len])
goto exit5;
4580 if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len])
goto exit5;
}
/* source should not be ancestor of target */
4584 error = -EINVAL;
4585 if (old_dentry == trap)
goto exit5;
/* target should not be an ancestor of source */
if (!(flags & RENAME_EXCHANGE))
4589 error = -ENOTEMPTY;
4590 if (new_dentry == trap)
goto exit5;
error = security_path_rename(&old_path, old_dentry,
&new_path, new_dentry, flags);
if (error)
goto exit5;
4597 error = vfs_rename(old_path.dentry->d_inode, old_dentry,
new_path.dentry->d_inode, new_dentry,
&delegated_inode, flags);
exit5:
4601 dput(new_dentry);
exit4:
4603 dput(old_dentry);
exit3:
4605 unlock_rename(new_path.dentry, old_path.dentry);
4606 if (delegated_inode) {
error = break_deleg_wait(&delegated_inode);
4608 if (!error)
goto retry_deleg;
}
4611 mnt_drop_write(old_path.mnt);
exit2:
if (retry_estale(error, lookup_flags))
should_retry = true;
path_put(&new_path);
4616 putname(to);
exit1:
path_put(&old_path);
4619 putname(from);
4620 if (should_retry) {
should_retry = false;
4622 lookup_flags |= LOOKUP_REVAL;
goto retry;
}
exit:
return error;
4627 }
4629 SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname,
int, newdfd, const char __user *, newname, unsigned int, flags)
{
4632 return do_renameat2(olddfd, oldname, newdfd, newname, flags);
}
4635 SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
int, newdfd, const char __user *, newname)
{
4638 return do_renameat2(olddfd, oldname, newdfd, newname, 0);
}
4641 SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname)
{
4643 return do_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
}
int vfs_whiteout(struct inode *dir, struct dentry *dentry)
4647 {
int error = may_create(dir, dentry);
4649 if (error)
return error;
4652 if (!dir->i_op->mknod)
4653 return -EPERM;
4655 return dir->i_op->mknod(dir, dentry,
S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
4657 }
EXPORT_SYMBOL(vfs_whiteout);
int readlink_copy(char __user *buffer, int buflen, const char *link)
4661 {
4662 int len = PTR_ERR(link);
4663 if (IS_ERR(link))
goto out;
4666 len = strlen(link);
if (len > (unsigned) buflen)
len = buflen;
4669 if (copy_to_user(buffer, link, len))
4670 len = -EFAULT;
out:
return len;
4673 }
/*
* A helper for ->readlink(). This should be used *ONLY* for symlinks that
* have ->get_link() not calling nd_jump_link(). Using (or not using) it
* for any given inode is up to filesystem.
*/
static int generic_readlink(struct dentry *dentry, char __user *buffer,
int buflen)
{
4683 DEFINE_DELAYED_CALL(done);
struct inode *inode = d_inode(dentry);
4685 const char *link = inode->i_link;
int res;
4688 if (!link) {
4689 link = inode->i_op->get_link(dentry, inode, &done);
4690 if (IS_ERR(link))
4691 return PTR_ERR(link);
}
4693 res = readlink_copy(buffer, buflen, link);
do_delayed_call(&done);
return res;
}
/**
* vfs_readlink - copy symlink body into userspace buffer
* @dentry: dentry on which to get symbolic link
* @buffer: user memory pointer
* @buflen: size of buffer
*
* Does not touch atime. That's up to the caller if necessary
*
* Does not call security hook.
*/
int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen)
4709 {
4710 struct inode *inode = d_inode(dentry);
4712 if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) {
4713 if (unlikely(inode->i_op->readlink))
4714 return inode->i_op->readlink(dentry, buffer, buflen);
4716 if (!d_is_symlink(dentry))
4717 return -EINVAL;
spin_lock(&inode->i_lock);
4720 inode->i_opflags |= IOP_DEFAULT_READLINK;
spin_unlock(&inode->i_lock);
}
return generic_readlink(dentry, buffer, buflen);
4725 }
EXPORT_SYMBOL(vfs_readlink);
/**
* vfs_get_link - get symlink body
* @dentry: dentry on which to get symbolic link
* @done: caller needs to free returned data with this
*
* Calls security hook and i_op->get_link() on the supplied inode.
*
* It does not touch atime. That's up to the caller if necessary.
*
* Does not work on "special" symlinks like /proc/$$/fd/N
*/
const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done)
4740 {
const char *res = ERR_PTR(-EINVAL);
4742 struct inode *inode = d_inode(dentry);
4744 if (d_is_symlink(dentry)) {
4745 res = ERR_PTR(security_inode_readlink(dentry));
4746 if (!res)
4747 res = inode->i_op->get_link(dentry, inode, done);
}
return res;
4750 }
EXPORT_SYMBOL(vfs_get_link);
/* get the link contents into pagecache */
const char *page_get_link(struct dentry *dentry, struct inode *inode,
struct delayed_call *callback)
4756 {
char *kaddr;
struct page *page;
4759 struct address_space *mapping = inode->i_mapping;
4761 if (!dentry) {
page = find_get_page(mapping, 0);
4763 if (!page)
return ERR_PTR(-ECHILD);
if (!PageUptodate(page)) {
put_page(page);
4767 return ERR_PTR(-ECHILD);
}
} else {
page = read_mapping_page(mapping, 0, NULL);
4771 if (IS_ERR(page))
return (char*)page;
}
set_delayed_call(callback, page_put_link, page);
4775 BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM);
kaddr = page_address(page);
nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1);
return kaddr;
4779 }
EXPORT_SYMBOL(page_get_link);
void page_put_link(void *arg)
4784 {
put_page(arg);
4786 }
EXPORT_SYMBOL(page_put_link);
int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
4790 {
4791 DEFINE_DELAYED_CALL(done);
4792 int res = readlink_copy(buffer, buflen,
page_get_link(dentry, d_inode(dentry),
&done));
do_delayed_call(&done);
return res;
4797 }
EXPORT_SYMBOL(page_readlink);
/*
* The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
*/
int __page_symlink(struct inode *inode, const char *symname, int len, int nofs)
4804 {
4805 struct address_space *mapping = inode->i_mapping;
struct page *page;
void *fsdata;
int err;
4809 unsigned int flags = 0;
if (nofs)
flags |= AOP_FLAG_NOFS;
retry:
4814 err = pagecache_write_begin(NULL, mapping, 0, len-1,
flags, &page, &fsdata);
4816 if (err)
goto fail;
4819 memcpy(page_address(page), symname, len-1);
4821 err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
page, fsdata);
4823 if (err < 0)
goto fail;
4825 if (err < len-1)
goto retry;
mark_inode_dirty(inode);
4829 return 0;
fail:
return err;
4832 }
EXPORT_SYMBOL(__page_symlink);
int page_symlink(struct inode *inode, const char *symname, int len)
4836 {
4837 return __page_symlink(inode, symname, len,
!mapping_gfp_constraint(inode->i_mapping, __GFP_FS));
}
EXPORT_SYMBOL(page_symlink);
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