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Message-Id: <f8b04df08a0dd950d47e17c901773258f0653eed.1424907511.git.agruenba@redhat.com>
Date: Thu, 26 Feb 2015 00:41:25 +0100
From: Andreas Gruenbacher <andreas.gruenbacher@...il.com>
To: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-nfs@...r.kernel.org
Subject: [RFC 04/21] vfs: Add MAY_CREATE_FILE and MAY_CREATE_DIR permission flags
Richacls distinguish between creating non-directories and directories. To
support that, add an isdir parameter to may_create(). When checking
inode_permission() for create permission, pass in an additional MAY_CREATE_FILE
or MAY_CREATE_DIR mask flag.
To allow checking for delete *and* create access when replacing an existing
file via vfs_rename(), add a replace parameter to may_delete().
Signed-off-by: Andreas Gruenbacher <agruenba@...hat.com>
---
fs/namei.c | 42 ++++++++++++++++++++++++------------------
include/linux/fs.h | 2 ++
2 files changed, 26 insertions(+), 18 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index 0ba4bbc..a8bc030 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -454,7 +454,8 @@ static int sb_permission(struct super_block *sb, struct inode *inode, int mask)
* 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.
+ * When checking for MAY_APPEND, MAY_CREATE_FILE, MAY_CREATE_DIR,
+ * MAY_WRITE must also be set in @mask.
*/
int inode_permission(struct inode *inode, int mask)
{
@@ -2447,10 +2448,11 @@ EXPORT_SYMBOL(__check_sticky);
* 10. 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)
+static int may_delete(struct inode *dir, struct dentry *victim,
+ bool isdir, bool replace)
{
struct inode *inode = victim->d_inode;
- int error;
+ int error, mask = MAY_WRITE | MAY_EXEC;
if (d_is_negative(victim))
return -ENOENT;
@@ -2459,7 +2461,9 @@ static int may_delete(struct inode *dir, struct dentry *victim, bool isdir)
BUG_ON(victim->d_parent->d_inode != dir);
audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE);
- error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
+ if (replace)
+ mask |= isdir ? MAY_CREATE_DIR : MAY_CREATE_FILE;
+ error = inode_permission(dir, mask);
if (error)
return error;
if (IS_APPEND(dir))
@@ -2490,14 +2494,16 @@ static int may_delete(struct inode *dir, struct dentry *victim, bool isdir)
* 3. We should have write and exec permissions on dir
* 4. We can't do it if dir is immutable (done in permission())
*/
-static inline int may_create(struct inode *dir, struct dentry *child)
+static inline int may_create(struct inode *dir, struct dentry *child, bool isdir)
{
+ int mask = isdir ? MAY_CREATE_DIR : MAY_CREATE_FILE;
+
audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE);
if (child->d_inode)
return -EEXIST;
if (IS_DEADDIR(dir))
return -ENOENT;
- return inode_permission(dir, MAY_WRITE | MAY_EXEC);
+ return inode_permission(dir, MAY_WRITE | MAY_EXEC | mask);
}
/*
@@ -2547,7 +2553,7 @@ EXPORT_SYMBOL(unlock_rename);
int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
bool want_excl)
{
- int error = may_create(dir, dentry);
+ int error = may_create(dir, dentry, false);
if (error)
return error;
@@ -3422,7 +3428,7 @@ EXPORT_SYMBOL(user_path_create);
int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
{
- int error = may_create(dir, dentry);
+ int error = may_create(dir, dentry, false);
if (error)
return error;
@@ -3514,7 +3520,7 @@ SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, d
int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
{
- int error = may_create(dir, dentry);
+ int error = may_create(dir, dentry, true);
unsigned max_links = dir->i_sb->s_max_links;
if (error)
@@ -3595,7 +3601,7 @@ EXPORT_SYMBOL(dentry_unhash);
int vfs_rmdir(struct inode *dir, struct dentry *dentry)
{
- int error = may_delete(dir, dentry, 1);
+ int error = may_delete(dir, dentry, true, false);
if (error)
return error;
@@ -3715,7 +3721,7 @@ SYSCALL_DEFINE1(rmdir, const char __user *, pathname)
int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode)
{
struct inode *target = dentry->d_inode;
- int error = may_delete(dir, dentry, 0);
+ int error = may_delete(dir, dentry, false, false);
if (error)
return error;
@@ -3847,7 +3853,7 @@ SYSCALL_DEFINE1(unlink, const char __user *, pathname)
int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
{
- int error = may_create(dir, dentry);
+ int error = may_create(dir, dentry, false);
if (error)
return error;
@@ -3930,7 +3936,7 @@ int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_de
if (!inode)
return -ENOENT;
- error = may_create(dir, new_dentry);
+ error = may_create(dir, new_dentry, false);
if (error)
return error;
@@ -4118,19 +4124,19 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
if (source == target)
return 0;
- error = may_delete(old_dir, old_dentry, is_dir);
+ error = may_delete(old_dir, old_dentry, is_dir, false);
if (error)
return error;
if (!target) {
- error = may_create(new_dir, new_dentry);
+ error = may_create(new_dir, new_dentry, is_dir);
} else {
new_is_dir = d_is_dir(new_dentry);
if (!(flags & RENAME_EXCHANGE))
- error = may_delete(new_dir, new_dentry, is_dir);
+ error = may_delete(new_dir, new_dentry, is_dir, true);
else
- error = may_delete(new_dir, new_dentry, new_is_dir);
+ error = may_delete(new_dir, new_dentry, new_is_dir, true);
}
if (error)
return error;
@@ -4394,7 +4400,7 @@ SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newna
int vfs_whiteout(struct inode *dir, struct dentry *dentry)
{
- int error = may_create(dir, dentry);
+ int error = may_create(dir, dentry, false);
if (error)
return error;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index f64eb45..bbe1d26 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -80,6 +80,8 @@ typedef void (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
#define MAY_CHDIR 0x00000040
/* called from RCU mode, don't block */
#define MAY_NOT_BLOCK 0x00000080
+#define MAY_CREATE_FILE 0x00000100
+#define MAY_CREATE_DIR 0x00000200
/*
* flags in file.f_mode. Note that FMODE_READ and FMODE_WRITE must correspond
--
2.1.0
--
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