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Message-Id: <20200720155902.181712-10-hch@lst.de>
Date: Mon, 20 Jul 2020 17:58:47 +0200
From: Christoph Hellwig <hch@....de>
To: Al Viro <viro@...iv.linux.org.uk>,
Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
linux-kernel@...r.kernel.org, linux-raid@...r.kernel.org,
linux-fsdevel@...r.kernel.org, linux-api@...r.kernel.org
Subject: [PATCH 09/24] fs: add a kern_chown helper
Add a simple helper to chown with a kernel space name and use it in the
early init code instead of relying on the implicit set_fs(KERNEL_DS)
there. Remove ksys_chown after switching all users to call do_fchownat
directly.
Signed-off-by: Christoph Hellwig <hch@....de>
---
fs/internal.h | 2 --
fs/open.c | 31 +++++++++++++++++++++----------
include/linux/fs.h | 1 +
include/linux/syscalls.h | 15 +--------------
init/initramfs.c | 6 +++---
kernel/uid16.c | 6 ++++--
6 files changed, 30 insertions(+), 31 deletions(-)
diff --git a/fs/internal.h b/fs/internal.h
index 9b863a7bd70892..ad62729e7ae587 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -127,8 +127,6 @@ extern int build_open_flags(const struct open_how *how, struct open_flags *op);
long do_sys_ftruncate(unsigned int fd, loff_t length, int small);
int do_fchmodat(int dfd, const char __user *filename, umode_t mode);
-int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
- int flag);
extern int vfs_open(const struct path *, struct file *);
diff --git a/fs/open.c b/fs/open.c
index 2a9457a16b2be2..7d7456070503f2 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -714,23 +714,23 @@ static int chown_common(const struct path *path, uid_t user, gid_t group)
return error;
}
-int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
+int do_fchownat(int dfd, struct filename *name, uid_t user, gid_t group,
int flag)
{
struct path path;
- int error = -EINVAL;
- int lookup_flags;
+ int lookup_flags, error;
+ error = -EINVAL;
if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
- goto out;
+ goto out_putname;
lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
if (flag & AT_EMPTY_PATH)
lookup_flags |= LOOKUP_EMPTY;
retry:
- error = user_path_at(dfd, filename, lookup_flags, &path);
+ error = filename_lookup(dfd, name, lookup_flags, &path, NULL);
if (error)
- goto out;
+ return error;
error = mnt_want_write(path.mnt);
if (error)
goto out_release;
@@ -742,24 +742,35 @@ int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
lookup_flags |= LOOKUP_REVAL;
goto retry;
}
-out:
+out_putname:
+ if (!IS_ERR(name))
+ putname(name);
return error;
}
+int __init kern_chown(const char *filename, uid_t user, gid_t group, int flag)
+{
+ return do_fchownat(AT_FDCWD, getname_kernel(filename), user, group,
+ flag);
+}
+
SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
gid_t, group, int, flag)
{
- return do_fchownat(dfd, filename, user, group, flag);
+ int lookup_flags = (flag & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
+ struct filename *name = getname_flags(filename, lookup_flags, NULL);
+
+ return do_fchownat(dfd, name, user, group, flag);
}
SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
{
- return do_fchownat(AT_FDCWD, filename, user, group, 0);
+ return do_fchownat(AT_FDCWD, getname(filename), user, group, 0);
}
SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
{
- return do_fchownat(AT_FDCWD, filename, user, group,
+ return do_fchownat(AT_FDCWD, getname(filename), user, group,
AT_SYMLINK_NOFOLLOW);
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 0c7672d3f1172f..75d6ef7e1de52b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3674,5 +3674,6 @@ static inline int inode_drain_writes(struct inode *inode)
int kern_chdir(const char *filename);
int kern_chroot(const char *filename);
int __init kern_access(const char *filename, int mode);
+int __init kern_chown(const char *filename, uid_t user, gid_t group, int flag);
#endif /* _LINUX_FS_H */
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index b387e3700c68c5..42dd2715e07688 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -1326,22 +1326,9 @@ static inline int ksys_chmod(const char __user *filename, umode_t mode)
return do_fchmodat(AT_FDCWD, filename, mode);
}
-extern int do_fchownat(int dfd, const char __user *filename, uid_t user,
+extern int do_fchownat(int dfd, struct filename *name, uid_t user,
gid_t group, int flag);
-static inline long ksys_chown(const char __user *filename, uid_t user,
- gid_t group)
-{
- return do_fchownat(AT_FDCWD, filename, user, group, 0);
-}
-
-static inline long ksys_lchown(const char __user *filename, uid_t user,
- gid_t group)
-{
- return do_fchownat(AT_FDCWD, filename, user, group,
- AT_SYMLINK_NOFOLLOW);
-}
-
extern long do_sys_ftruncate(unsigned int fd, loff_t length, int small);
static inline long ksys_ftruncate(unsigned int fd, loff_t length)
diff --git a/init/initramfs.c b/init/initramfs.c
index 3823d15e5d2619..45e4ddb63caba1 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -345,14 +345,14 @@ static int __init do_name(void)
}
} else if (S_ISDIR(mode)) {
ksys_mkdir(collected, mode);
- ksys_chown(collected, uid, gid);
+ kern_chown(collected, uid, gid, 0);
ksys_chmod(collected, mode);
dir_add(collected, mtime);
} else if (S_ISBLK(mode) || S_ISCHR(mode) ||
S_ISFIFO(mode) || S_ISSOCK(mode)) {
if (maybe_link() == 0) {
ksys_mknod(collected, mode, rdev);
- ksys_chown(collected, uid, gid);
+ kern_chown(collected, uid, gid, 0);
ksys_chmod(collected, mode);
do_utime(collected, mtime);
}
@@ -390,7 +390,7 @@ static int __init do_symlink(void)
collected[N_ALIGN(name_len) + body_len] = '\0';
clean_path(collected, 0);
ksys_symlink(collected + N_ALIGN(name_len), collected);
- ksys_lchown(collected, uid, gid);
+ kern_chown(collected, uid, gid, AT_SYMLINK_NOFOLLOW);
do_utime(collected, mtime);
state = SkipIt;
next_state = Reset;
diff --git a/kernel/uid16.c b/kernel/uid16.c
index af6925d8599b9b..a332947e92d12e 100644
--- a/kernel/uid16.c
+++ b/kernel/uid16.c
@@ -22,12 +22,14 @@
SYSCALL_DEFINE3(chown16, const char __user *, filename, old_uid_t, user, old_gid_t, group)
{
- return ksys_chown(filename, low2highuid(user), low2highgid(group));
+ return do_fchownat(AT_FDCWD, getname(filename), low2highuid(user),
+ low2highgid(group), 0);
}
SYSCALL_DEFINE3(lchown16, const char __user *, filename, old_uid_t, user, old_gid_t, group)
{
- return ksys_lchown(filename, low2highuid(user), low2highgid(group));
+ return do_fchownat(AT_FDCWD, getname(filename), low2highuid(user),
+ low2highgid(group), AT_SYMLINK_NOFOLLOW);
}
SYSCALL_DEFINE3(fchown16, unsigned int, fd, old_uid_t, user, old_gid_t, group)
--
2.27.0
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