From: Miklos Szeredi <mszeredi@redhat.com>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Subject: [PATCH 07/12] f*xattr: allow O_PATH descriptors
Date: Thu, 28 Nov 2019 16:59:35 +0100 [thread overview]
Message-ID: <20191128155940.17530-8-mszeredi@redhat.com> (raw)
In-Reply-To: <20191128155940.17530-1-mszeredi@redhat.com>
This allows xattr ops on symlink/special files referenced by an O_PATH
descriptor without having to play games with /proc/self/fd/NN (which
doesn't work for symlinks anyway).
This capability is the same as would be given by introducing ...at()
variants with an AT_EMPTY_PATH argument. Looking at getattr/setattr type
syscalls, this is allowed for fstatat() and fchownat(), but not for
fchmodat() and utimensat(). What's the logic?
While this carries a minute risk of someone relying on the property of
xattr syscalls rejecting O_PATH descriptors, it saves the trouble of
introducing another set of syscalls.
Only file->f_path and file->f_inode are accessed in these functions.
Current versions return EBADF, hence easy to detect the presense of this
feature and fall back in case it's missing.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
fs/xattr.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/fs/xattr.c b/fs/xattr.c
index 90dd78f0eb27..fd1335b86e60 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -495,7 +495,7 @@ SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
const void __user *,value, size_t, size, int, flags)
{
- struct fd f = fdget(fd);
+ struct fd f = fdget_raw(fd);
int error = -EBADF;
if (!f.file)
@@ -587,7 +587,7 @@ SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
void __user *, value, size_t, size)
{
- struct fd f = fdget(fd);
+ struct fd f = fdget_raw(fd);
ssize_t error = -EBADF;
if (!f.file)
@@ -662,7 +662,7 @@ SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
{
- struct fd f = fdget(fd);
+ struct fd f = fdget_raw(fd);
ssize_t error = -EBADF;
if (!f.file)
@@ -727,7 +727,7 @@ SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
{
- struct fd f = fdget(fd);
+ struct fd f = fdget_raw(fd);
int error = -EBADF;
if (!f.file)
--
2.21.0
next prev parent reply other threads:[~2019-11-28 15:59 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-28 15:59 [PATCH 00/12] various vfs patches Miklos Szeredi
2019-11-28 15:59 ` [PATCH 01/12] aio: fix async fsync creds Miklos Szeredi
2019-12-13 9:32 ` Miklos Szeredi
2020-05-04 8:05 ` Avi Kivity
2019-11-28 15:59 ` [PATCH 02/12] fs_parse: fix fs_param_v_optional handling Miklos Szeredi
2019-11-29 11:31 ` Andrew Price
2019-11-29 14:43 ` Miklos Szeredi
2019-11-29 15:56 ` Andrew Price
2019-12-16 23:28 ` Al Viro
2019-12-17 1:18 ` Al Viro
2019-12-17 3:27 ` Al Viro
2019-11-28 15:59 ` [PATCH 03/12] vfs: verify param type in vfs_parse_sb_flag() Miklos Szeredi
2019-11-28 15:59 ` [PATCH 04/12] uapi: deprecate STATX_ALL Miklos Szeredi
2019-11-28 15:59 ` [PATCH 05/12] statx: don't clear STATX_ATIME on SB_RDONLY Miklos Szeredi
2019-11-28 15:59 ` [PATCH 06/12] utimensat: AT_EMPTY_PATH support Miklos Szeredi
2019-11-28 15:59 ` Miklos Szeredi [this message]
2019-11-28 15:59 ` [PATCH 08/12] vfs: allow unprivileged whiteout creation Miklos Szeredi
2019-12-17 3:51 ` Al Viro
2019-12-17 4:22 ` Miklos Szeredi
2019-11-28 15:59 ` [PATCH 09/12] fs_parser: "string" with missing value is a "flag" Miklos Szeredi
2019-12-17 17:32 ` Al Viro
2019-12-17 18:31 ` Al Viro
2019-11-28 15:59 ` [PATCH 10/12] vfs: don't parse forbidden flags Miklos Szeredi
2019-11-28 15:59 ` [PATCH 11/12] vfs: don't parse "posixacl" option Miklos Szeredi
2019-12-17 3:42 ` Al Viro
2019-12-17 4:18 ` Miklos Szeredi
2019-12-17 4:28 ` Al Viro
2019-11-28 15:59 ` [PATCH 12/12] vfs: don't parse "silent" option Miklos Szeredi
2019-12-17 3:37 ` Al Viro
2019-12-17 4:12 ` Miklos Szeredi
2019-12-17 4:16 ` Miklos Szeredi
2019-12-17 4:19 ` Al Viro
2019-12-17 4:23 ` Miklos Szeredi
2019-12-17 4:28 ` Miklos Szeredi
2019-12-17 4:17 ` Al Viro
2019-12-13 9:33 ` [PATCH 00/12] various vfs patches Miklos Szeredi
2019-12-16 23:13 ` Al Viro
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