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Message-ID: <20241101193703.3282039-1-stefanb@linux.vnet.ibm.com>
Date: Fri, 1 Nov 2024 15:37:03 -0400
From: Stefan Berger <stefanb@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: Stefan Berger <stefanb@...ux.ibm.com>, Al Viro <viro@...iv.linux.org.uk>,
Tyler Hicks <code@...icks.com>, ecryptfs@...r.kernel.org,
Miklos Szeredi <miklos@...redi.hu>,
Amir Goldstein <amir73il@...il.com>, linux-unionfs@...r.kernel.org,
Christian Brauner <brauner@...nel.org>, linux-fsdevel@...r.kernel.org
Subject: [PATCH] fs: Simplify getattr interface function checking AT_GETATTR_NOSEC flag
From: Stefan Berger <stefanb@...ux.ibm.com>
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 originan 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 <viro@...iv.linux.org.uk>
Closes: https://lore.kernel.org/linux-fsdevel/20241101011724.GN1350452@ZenIV/T/#u
Cc: Tyler Hicks <code@...icks.com>
Cc: ecryptfs@...r.kernel.org
Cc: Miklos Szeredi <miklos@...redi.hu>
Cc: Amir Goldstein <amir73il@...il.com>
Cc: linux-unionfs@...r.kernel.org
Cc: Christian Brauner <brauner@...nel.org>
Cc: linux-fsdevel@...r.kernel.org
Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
---
fs/ecryptfs/inode.c | 12 ++----------
fs/overlayfs/inode.c | 10 +++++-----
fs/overlayfs/overlayfs.h | 8 --------
fs/stat.c | 5 +----
include/uapi/linux/fcntl.h | 4 ----
5 files changed, 8 insertions(+), 31 deletions(-)
diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index cbdf82f0183f..a9819ddb1ab8 100644
--- 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 35fd3e3e1778..8b31f44c12cd 100644
--- 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 0bfe35da4b7b..910dbbb2bb7b 100644
--- 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 41e598376d7e..cbc0fcd4fba3 100644
--- 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 87e2dec79fea..a40833bf2855 100644
--- 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 */
--
2.47.0
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