Commit Graph

2 Commits

Author SHA1 Message Date
Christian Göttsche
6140be90ec fs/xattr: add *at family syscalls
Add the four syscalls setxattrat(), getxattrat(), listxattrat() and
removexattrat().  Those can be used to operate on extended attributes,
especially security related ones, either relative to a pinned directory
or on a file descriptor without read access, avoiding a
/proc/<pid>/fd/<fd> detour, requiring a mounted procfs.

One use case will be setfiles(8) setting SELinux file contexts
("security.selinux") without race conditions and without a file
descriptor opened with read access requiring SELinux read permission.

Use the do_{name}at() pattern from fs/open.c.

Pass the value of the extended attribute, its length, and for
setxattrat(2) the command (XATTR_CREATE or XATTR_REPLACE) via an added
struct xattr_args to not exceed six syscall arguments and not
merging the AT_* and XATTR_* flags.

[AV: fixes by Christian Brauner folded in, the entire thing rebased on
top of {filename,file}_...xattr() primitives, treatment of empty
pathnames regularized.  As the result, AT_EMPTY_PATH+NULL handling
is cheap, so f...(2) can use it]

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Link: https://lore.kernel.org/r/20240426162042.191916-1-cgoettsche@seltendoof.de
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
CC: x86@kernel.org
CC: linux-alpha@vger.kernel.org
CC: linux-kernel@vger.kernel.org
CC: linux-arm-kernel@lists.infradead.org
CC: linux-ia64@vger.kernel.org
CC: linux-m68k@lists.linux-m68k.org
CC: linux-mips@vger.kernel.org
CC: linux-parisc@vger.kernel.org
CC: linuxppc-dev@lists.ozlabs.org
CC: linux-s390@vger.kernel.org
CC: linux-sh@vger.kernel.org
CC: sparclinux@vger.kernel.org
CC: linux-fsdevel@vger.kernel.org
CC: audit@vger.kernel.org
CC: linux-arch@vger.kernel.org
CC: linux-api@vger.kernel.org
CC: linux-security-module@vger.kernel.org
CC: selinux@vger.kernel.org
[brauner: slight tweaks]
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-11-06 12:59:44 -05:00
Arnd Bergmann
7fe33e9f66 arm64: convert unistd_32.h to syscall.tbl format
This is a straight conversion from the old asm/unistd32.h into the
format used by 32-bit arm and most other architectures, calling scripts
to generate the asm/unistd32.h header and a new asm/syscalls32.h headers.

I used a semi-automated text replacement method to do the conversion,
and then used 'vimdiff' to synchronize the whitespace and the (unused)
names of the non-compat syscalls with the arm version.

There are two differences between the generated syscalls names and the
old version:

 - the old asm/unistd32.h contained only a __NR_sync_file_range2
   entry, while the arm32 version also defines
   __NR_arm_sync_file_range with the same number. I added this
   duplicate back in asm/unistd32.h.

 - __NR__sysctl was removed from the arm64 file a while ago, but
   all the tables still contain it. This should probably get removed
   everywhere but I added it here for consistency.

On top of that, the arm64 version does not contain any references to
the 32-bit OABI syscalls that are not supported by arm64. If we ever
want to share the file between arm32 and arm64, it would not be
hard to add support for both in one file.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2024-07-10 14:23:38 +02:00