fs: Simplify getattr interface function checking AT_GETATTR_NOSEC flag

Commit 8a924db2d7b5 ("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: 8a924db2d7b5 ("fs: Pass AT_GETATTR_NOSEC flag to getattr interface function")
Reported-by: Al Viro <[email protected]>
Closes: https://lore.kernel.org/linux-fsdevel/20241101011724.GN1350452@ZenIV/T/#u
Cc: Tyler Hicks <[email protected]>
Cc: [email protected]
Cc: Miklos Szeredi <[email protected]>
Cc: Amir Goldstein <[email protected]>
Cc: [email protected]
Cc: Christian Brauner <[email protected]>
Cc: [email protected]
Reviewed-by: Christian Brauner <[email protected]>
Signed-off-by: Stefan Berger <[email protected]>
Signed-off-by: Al Viro <[email protected]>

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 5ed1e4cf6c0b4ecbf4efd55169374a3d4fca3e87..644e973d5a77c8af9a6aac4d6abab4728378dfeb 100644 (file)
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -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)));

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 35fd3e3e177807fd5d157f4e9d93b1e7f198610a..8b31f44c12cd60b048447e85e0eb781f866500c5 100644 (file)
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -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 {

diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 0bfe35da4b7b7a92b032a26369ae0d89c014bad3..910dbbb2bb7b390be8d57db9ef1508ef9c740ec4 100644 (file)
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -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);

diff --git a/fs/stat.c b/fs/stat.c
index 855b995ad09bd8c79ade51f9eb7a279628f2e293..011d2160b7affab0bdce3659b6f6ab6b13ecce02 100644 (file)
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -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;

diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h
index 87e2dec79fea4ef21e694f3c069ec229926b6d08..a40833bf2855e3a781abe548f8e8a47861c66e2e 100644 (file)
--- a/include/uapi/linux/fcntl.h
+++ b/include/uapi/linux/fcntl.h
@@ -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 */