From: Stas Sergeev <stsp2@yandex.ru>
To: linux-kernel@vger.kernel.org
Cc: "Stas Sergeev" <stsp2@yandex.ru>,
"Stefan Metzmacher" <metze@samba.org>,
"Eric Biederman" <ebiederm@xmission.com>,
"Alexander Viro" <viro@zeniv.linux.org.uk>,
"Andy Lutomirski" <luto@kernel.org>,
"Christian Brauner" <brauner@kernel.org>,
"Jan Kara" <jack@suse.cz>, "Jeff Layton" <jlayton@kernel.org>,
"Chuck Lever" <chuck.lever@oracle.com>,
"Alexander Aring" <alex.aring@gmail.com>,
"David Laight" <David.Laight@ACULAB.COM>,
linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Christian Göttsche" <cgzones@googlemail.com>,
"Arnd Bergmann" <arnd@arndb.de>,
"David S. Miller" <davem@davemloft.net>,
"Eric Dumazet" <edumazet@google.com>,
"Jakub Kicinski" <kuba@kernel.org>,
"Paolo Abeni" <pabeni@redhat.com>, "Jens Axboe" <axboe@kernel.dk>,
"Kuniyuki Iwashima" <kuniyu@amazon.com>,
"Pavel Begunkov" <asml.silence@gmail.com>,
linux-arch@vger.kernel.org, netdev@vger.kernel.org
Subject: [PATCH v5 2/3] open: add O_CRED_ALLOW flag
Date: Fri, 26 Apr 2024 16:33:09 +0300 [thread overview]
Message-ID: <20240426133310.1159976-3-stsp2@yandex.ru> (raw)
In-Reply-To: <20240426133310.1159976-1-stsp2@yandex.ru>
This flag prevents an fd from being passed via unix socket, and
makes it to be always closed on exec().
It is needed for the subsequent OA2_CRED_INHERIT addition, to work
as an "opt-in" for the new cred-inherit functionality. Without using
O_CRED_ALLOW when opening dir fd, it won't be possible to use
OA2_CRED_INHERIT on that dir fd.
Signed-off-by: Stas Sergeev <stsp2@yandex.ru>
CC: Eric Biederman <ebiederm@xmission.com>
CC: Alexander Viro <viro@zeniv.linux.org.uk>
CC: Christian Brauner <brauner@kernel.org>
CC: Jan Kara <jack@suse.cz>
CC: Andy Lutomirski <luto@kernel.org>
CC: David Laight <David.Laight@ACULAB.COM>
CC: Arnd Bergmann <arnd@arndb.de>
CC: "David S. Miller" <davem@davemloft.net>
CC: Eric Dumazet <edumazet@google.com>
CC: Jakub Kicinski <kuba@kernel.org>
CC: Paolo Abeni <pabeni@redhat.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: Kuniyuki Iwashima <kuniyu@amazon.com>
CC: Pavel Begunkov <asml.silence@gmail.com>
CC: linux-arch@vger.kernel.org
CC: netdev@vger.kernel.org
CC: linux-fsdevel@vger.kernel.org
CC: linux-kernel@vger.kernel.org
CC: linux-api@vger.kernel.org
---
fs/fcntl.c | 2 +-
fs/file.c | 15 ++++++++-------
include/linux/fcntl.h | 2 +-
include/uapi/asm-generic/fcntl.h | 4 ++++
net/core/scm.c | 5 +++++
5 files changed, 19 insertions(+), 9 deletions(-)
diff --git a/fs/fcntl.c b/fs/fcntl.c
index 54cc85d3338e..78c96b1293c2 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -1039,7 +1039,7 @@ static int __init fcntl_init(void)
* Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY
* is defined as O_NONBLOCK on some platforms and not on others.
*/
- BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ !=
+ BUILD_BUG_ON(22 - 1 /* for O_RDONLY being 0 */ !=
HWEIGHT32(
(VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) |
__FMODE_EXEC | __FMODE_NONOTIFY));
diff --git a/fs/file.c b/fs/file.c
index 3b683b9101d8..2a09d5276676 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -827,22 +827,23 @@ void do_close_on_exec(struct files_struct *files)
/* exec unshares first */
spin_lock(&files->file_lock);
for (i = 0; ; i++) {
+ int j;
unsigned long set;
unsigned fd = i * BITS_PER_LONG;
fdt = files_fdtable(files);
if (fd >= fdt->max_fds)
break;
set = fdt->close_on_exec[i];
- if (!set)
- continue;
fdt->close_on_exec[i] = 0;
- for ( ; set ; fd++, set >>= 1) {
- struct file *file;
- if (!(set & 1))
- continue;
- file = fdt->fd[fd];
+ for (j = 0; j < BITS_PER_LONG; j++, fd++, set >>= 1) {
+ struct file *file = fdt->fd[fd];
if (!file)
continue;
+ /* Close all cred-allow files. */
+ if (file->f_flags & O_CRED_ALLOW)
+ set |= 1;
+ if (!(set & 1))
+ continue;
rcu_assign_pointer(fdt->fd[fd], NULL);
__put_unused_fd(files, fd);
spin_unlock(&files->file_lock);
diff --git a/include/linux/fcntl.h b/include/linux/fcntl.h
index a332e79b3207..e074ee9c1e36 100644
--- a/include/linux/fcntl.h
+++ b/include/linux/fcntl.h
@@ -10,7 +10,7 @@
(O_RDONLY | O_WRONLY | O_RDWR | O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC | \
O_APPEND | O_NDELAY | O_NONBLOCK | __O_SYNC | O_DSYNC | \
FASYNC | O_DIRECT | O_LARGEFILE | O_DIRECTORY | O_NOFOLLOW | \
- O_NOATIME | O_CLOEXEC | O_PATH | __O_TMPFILE)
+ O_NOATIME | O_CLOEXEC | O_PATH | __O_TMPFILE | O_CRED_ALLOW)
/* List of all valid flags for the how->resolve argument: */
#define VALID_RESOLVE_FLAGS \
diff --git a/include/uapi/asm-generic/fcntl.h b/include/uapi/asm-generic/fcntl.h
index 80f37a0d40d7..ee8c2267c516 100644
--- a/include/uapi/asm-generic/fcntl.h
+++ b/include/uapi/asm-generic/fcntl.h
@@ -89,6 +89,10 @@
#define __O_TMPFILE 020000000
#endif
+#ifndef O_CRED_ALLOW
+#define O_CRED_ALLOW 040000000
+#endif
+
/* a horrid kludge trying to make sure that this will fail on old kernels */
#define O_TMPFILE (__O_TMPFILE | O_DIRECTORY)
diff --git a/net/core/scm.c b/net/core/scm.c
index 9cd4b0a01cd6..f54fb0ee9727 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -111,6 +111,11 @@ static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
fput(file);
return -EINVAL;
}
+ /* don't allow files with creds */
+ if (file->f_flags & O_CRED_ALLOW) {
+ fput(file);
+ return -EPERM;
+ }
if (unix_get_socket(file))
fpl->count_unix++;
--
2.44.0
next prev parent reply other threads:[~2024-04-26 13:34 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-26 13:33 [PATCH v5 0/3] implement OA2_CRED_INHERIT flag for openat2() Stas Sergeev
2024-04-26 13:33 ` [PATCH v5 1/3] fs: reorganize path_openat() Stas Sergeev
2024-04-26 13:33 ` Stas Sergeev [this message]
2024-04-27 2:12 ` [PATCH v5 2/3] open: add O_CRED_ALLOW flag kernel test robot
2024-04-26 13:33 ` [PATCH v5 3/3] openat2: add OA2_CRED_INHERIT flag Stas Sergeev
2024-04-28 16:41 ` [PATCH v5 0/3] implement OA2_CRED_INHERIT flag for openat2() Andy Lutomirski
2024-04-28 17:39 ` stsp
2024-04-28 19:15 ` stsp
2024-04-28 20:19 ` Andy Lutomirski
2024-04-28 21:14 ` stsp
2024-04-28 21:30 ` Andy Lutomirski
2024-04-28 22:12 ` stsp
2024-04-29 1:12 ` stsp
2024-04-29 9:12 ` Christian Brauner
2024-05-06 7:13 ` Aleksa Sarai
2024-05-06 17:29 ` Andy Lutomirski
2024-05-06 17:34 ` Andy Lutomirski
2024-05-06 19:34 ` David Laight
2024-05-06 21:53 ` Andy Lutomirski
2024-05-07 7:42 ` Christian Brauner
2024-05-07 20:38 ` Andy Lutomirski
2024-05-08 7:32 ` Christian Brauner
2024-05-08 17:30 ` Andy Lutomirski
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