From 6140be90ec70c39fa844741ca3cc807dd0866394 Mon Sep 17 00:00:00 2001 From: Christian Göttsche Date: Fri, 26 Apr 2024 18:20:14 +0200 Subject: fs/xattr: add *at family syscalls MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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//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 Link: https://lore.kernel.org/r/20240426162042.191916-1-cgoettsche@seltendoof.de Reviewed-by: Arnd Bergmann Reviewed-by: Christian Brauner 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 Signed-off-by: Al Viro --- include/uapi/asm-generic/unistd.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'include/uapi/asm-generic') diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h index 5bf6148cac2b..88dc393c2bca 100644 --- a/include/uapi/asm-generic/unistd.h +++ b/include/uapi/asm-generic/unistd.h @@ -841,8 +841,17 @@ __SYSCALL(__NR_lsm_list_modules, sys_lsm_list_modules) #define __NR_mseal 462 __SYSCALL(__NR_mseal, sys_mseal) +#define __NR_setxattrat 463 +__SYSCALL(__NR_setxattrat, sys_setxattrat) +#define __NR_getxattrat 464 +__SYSCALL(__NR_getxattrat, sys_getxattrat) +#define __NR_listxattrat 465 +__SYSCALL(__NR_listxattrat, sys_listxattrat) +#define __NR_removexattrat 466 +__SYSCALL(__NR_removexattrat, sys_removexattrat) + #undef __NR_syscalls -#define __NR_syscalls 463 +#define __NR_syscalls 467 /* * 32 bit systems traditionally used different -- cgit v1.2.3