diff mbox series

[v5,2/3] open: add O_CRED_ALLOW flag

Message ID 20240426133310.1159976-3-stsp2@yandex.ru (mailing list archive)
State Not Applicable
Delegated to: Netdev Maintainers
Headers show
Series None | expand

Commit Message

stsp April 26, 2024, 1:33 p.m. UTC
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(-)

Comments

kernel test robot April 27, 2024, 2:12 a.m. UTC | #1
Hi Stas,

kernel test robot noticed the following build errors:

[auto build test ERROR on linus/master]
[also build test ERROR on v6.9-rc5 next-20240426]
[cannot apply to arnd-asm-generic/master]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Stas-Sergeev/fs-reorganize-path_openat/20240426-214030
base:   linus/master
patch link:    https://lore.kernel.org/r/20240426133310.1159976-3-stsp2%40yandex.ru
patch subject: [PATCH v5 2/3] open: add O_CRED_ALLOW flag
config: parisc-allnoconfig (https://download.01.org/0day-ci/archive/20240427/202404270923.bAeBIJt1-lkp@intel.com/config)
compiler: hppa-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240427/202404270923.bAeBIJt1-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202404270923.bAeBIJt1-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from <command-line>:
   fs/fcntl.c: In function 'fcntl_init':
>> include/linux/compiler_types.h:449:45: error: call to '__compiletime_assert_297' declared with attribute error: BUILD_BUG_ON failed: 22 - 1 != HWEIGHT32( (VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) | __FMODE_EXEC | __FMODE_NONOTIFY)
     449 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
         |                                             ^
   include/linux/compiler_types.h:430:25: note: in definition of macro '__compiletime_assert'
     430 |                         prefix ## suffix();                             \
         |                         ^~~~~~
   include/linux/compiler_types.h:449:9: note: in expansion of macro '_compiletime_assert'
     449 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
         |         ^~~~~~~~~~~~~~~~~~~
   include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert'
      39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
         |                                     ^~~~~~~~~~~~~~~~~~
   include/linux/build_bug.h:50:9: note: in expansion of macro 'BUILD_BUG_ON_MSG'
      50 |         BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
         |         ^~~~~~~~~~~~~~~~
   fs/fcntl.c:1042:9: note: in expansion of macro 'BUILD_BUG_ON'
    1042 |         BUILD_BUG_ON(22 - 1 /* for O_RDONLY being 0 */ !=
         |         ^~~~~~~~~~~~


vim +/__compiletime_assert_297 +449 include/linux/compiler_types.h

eb5c2d4b45e3d2 Will Deacon 2020-07-21  435  
eb5c2d4b45e3d2 Will Deacon 2020-07-21  436  #define _compiletime_assert(condition, msg, prefix, suffix) \
eb5c2d4b45e3d2 Will Deacon 2020-07-21  437  	__compiletime_assert(condition, msg, prefix, suffix)
eb5c2d4b45e3d2 Will Deacon 2020-07-21  438  
eb5c2d4b45e3d2 Will Deacon 2020-07-21  439  /**
eb5c2d4b45e3d2 Will Deacon 2020-07-21  440   * compiletime_assert - break build and emit msg if condition is false
eb5c2d4b45e3d2 Will Deacon 2020-07-21  441   * @condition: a compile-time constant condition to check
eb5c2d4b45e3d2 Will Deacon 2020-07-21  442   * @msg:       a message to emit if condition is false
eb5c2d4b45e3d2 Will Deacon 2020-07-21  443   *
eb5c2d4b45e3d2 Will Deacon 2020-07-21  444   * In tradition of POSIX assert, this macro will break the build if the
eb5c2d4b45e3d2 Will Deacon 2020-07-21  445   * supplied condition is *false*, emitting the supplied error message if the
eb5c2d4b45e3d2 Will Deacon 2020-07-21  446   * compiler has support to do so.
eb5c2d4b45e3d2 Will Deacon 2020-07-21  447   */
eb5c2d4b45e3d2 Will Deacon 2020-07-21  448  #define compiletime_assert(condition, msg) \
eb5c2d4b45e3d2 Will Deacon 2020-07-21 @449  	_compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
eb5c2d4b45e3d2 Will Deacon 2020-07-21  450
diff mbox series

Patch

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++;