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fs: Simplify getattr interface function checking AT_GETATTR_NOSEC flag

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Commit 8a924db2d7 ("fs: Pass AT_GETATTR_NOSEC flag to getattr interface
function")' introduced the AT_GETATTR_NOSEC flag to ensure that the
call paths only call vfs_getattr_nosec if it is set instead of vfs_getattr.
Now, simplify the getattr interface functions of filesystems where the flag
AT_GETATTR_NOSEC is checked.

There is only a single caller of inode_operations getattr function and it
is located in fs/stat.c in vfs_getattr_nosec. The caller there is the only
one from which the AT_GETATTR_NOSEC flag is passed from.

Two filesystems are checking this flag in .getattr and the flag is always
passed to them unconditionally from only vfs_getattr_nosec:

- ecryptfs:  Simplify by always calling vfs_getattr_nosec in
             ecryptfs_getattr. From there the flag is passed to no other
             function and this function is not called otherwise.

- overlayfs: Simplify by always calling vfs_getattr_nosec in
             ovl_getattr. From there the flag is passed to no other
             function and this function is not called otherwise.

The query_flags in vfs_getattr_nosec will mask-out AT_GETATTR_NOSEC from
any caller using AT_STATX_SYNC_TYPE as mask so that the flag is not
important inside this function. Also, since no filesystem is checking the
flag anymore, remove the flag entirely now, including the BUG_ON check that
never triggered.

The net change of the changes here combined with the original commit is
that ecryptfs and overlayfs do not call vfs_getattr but only
vfs_getattr_nosec.

Fixes: 8a924db2d7 ("fs: Pass AT_GETATTR_NOSEC flag to getattr interface function")
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Closes: https://lore.kernel.org/linux-fsdevel/20241101011724.GN1350452@ZenIV/T/#u
Cc: Tyler Hicks <code@tyhicks.com>
Cc: ecryptfs@vger.kernel.org
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: linux-unionfs@vger.kernel.org
Cc: Christian Brauner <brauner@kernel.org>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Stefan Berger 2024-11-01 15:37:03 -04:00 committed by Al Viro
parent 0dd4fb7331
commit 95f567f81e
5 changed files with 8 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
fs/ecryptfs/inode.c
View File

@ -1008,14 +1008,6 @@ static int ecryptfs_getattr_link(struct mnt_idmap *idmap,
return rc;
}
static int ecryptfs_do_getattr(const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int flags)
{
if (flags & AT_GETATTR_NOSEC)
return vfs_getattr_nosec(path, stat, request_mask, flags);
return vfs_getattr(path, stat, request_mask, flags);
}
static int ecryptfs_getattr(struct mnt_idmap *idmap,
const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int flags)
@ -1024,8 +1016,8 @@ static int ecryptfs_getattr(struct mnt_idmap *idmap,
struct kstat lower_stat;
int rc;
rc = ecryptfs_do_getattr(ecryptfs_dentry_to_lower_path(dentry),
&lower_stat, request_mask, flags);
rc = vfs_getattr_nosec(ecryptfs_dentry_to_lower_path(dentry),
&lower_stat, request_mask, flags);
if (!rc) {
fsstack_copy_attr_all(d_inode(dentry),
ecryptfs_inode_to_lower(d_inode(dentry)));

10
fs/overlayfs/inode.c
View File

@ -170,7 +170,7 @@ int ovl_getattr(struct mnt_idmap *idmap, const struct path *path,
type = ovl_path_real(dentry, &realpath);
old_cred = ovl_override_creds(dentry->d_sb);
err = ovl_do_getattr(&realpath, stat, request_mask, flags);
err = vfs_getattr_nosec(&realpath, stat, request_mask, flags);
if (err)
goto out;
@ -195,8 +195,8 @@ int ovl_getattr(struct mnt_idmap *idmap, const struct path *path,
(!is_dir ? STATX_NLINK : 0);
ovl_path_lower(dentry, &realpath);
err = ovl_do_getattr(&realpath, &lowerstat, lowermask,
flags);
err = vfs_getattr_nosec(&realpath, &lowerstat, lowermask,
flags);
if (err)
goto out;
@ -248,8 +248,8 @@ int ovl_getattr(struct mnt_idmap *idmap, const struct path *path,
ovl_path_lowerdata(dentry, &realpath);
if (realpath.dentry) {
err = ovl_do_getattr(&realpath, &lowerdatastat,
lowermask, flags);
err = vfs_getattr_nosec(&realpath, &lowerdatastat,
lowermask, flags);
if (err)
goto out;
} else {

8
fs/overlayfs/overlayfs.h
View File

@ -412,14 +412,6 @@ static inline bool ovl_open_flags_need_copy_up(int flags)
return ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC));
}
static inline int ovl_do_getattr(const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int flags)
{
if (flags & AT_GETATTR_NOSEC)
return vfs_getattr_nosec(path, stat, request_mask, flags);
return vfs_getattr(path, stat, request_mask, flags);
}
/* util.c */
int ovl_get_write_access(struct dentry *dentry);
void ovl_put_write_access(struct dentry *dentry);

5
fs/stat.c
View File

@ -165,7 +165,7 @@ int vfs_getattr_nosec(const struct path *path, struct kstat *stat,
if (inode->i_op->getattr)
return inode->i_op->getattr(idmap, path, stat,
request_mask,
query_flags | AT_GETATTR_NOSEC);
query_flags);
generic_fillattr(idmap, request_mask, inode, stat);
return 0;
@ -198,9 +198,6 @@ int vfs_getattr(const struct path *path, struct kstat *stat,
{
int retval;
if (WARN_ON_ONCE(query_flags & AT_GETATTR_NOSEC))
return -EPERM;
retval = security_inode_getattr(path);
if (retval)
return retval;

4
include/uapi/linux/fcntl.h
View File

@ -154,8 +154,4 @@
usable with open_by_handle_at(2). */
#define AT_HANDLE_MNT_ID_UNIQUE 0x001 /* Return the u64 unique mount ID. */
#if defined(__KERNEL__)
#define AT_GETATTR_NOSEC 0x80000000
#endif
#endif /* _UAPI_LINUX_FCNTL_H */