In glibc, the fchmodat(3) function has a flags argument according to the POSIX specification [1], but kernel syscalls has no such argument. Therefore, libc implementations do workarounds using /proc. However, this requires procfs to be mounted and accessible. This patch set adds fchmodat2(), a new syscall. The syscall allows to pass the AT_SYMLINK_NOFOLLOW flag to disable LOOKUP_FOLLOW. In all other respects, this syscall is no different from fchmodat(). [1] https://pubs.opengroup.org/onlinepubs/9699919799/functions/chmod.html Changes since v3 [cover.1689074739.git.legion@xxxxxxxxxx]: * Rebased to master because a new syscall has appeared in master. * Increased __NR_compat_syscalls as pointed out by Arnd Bergmann. * Syscall renamed fchmodat4 -> fchmodat2 as suggested by Christian Brauner. * Returned do_fchmodat4() the original name. We don't need to version internal functions. * Fixed warnings found by checkpatch.pl. Changes since v2 [20190717012719.5524-1-palmer@xxxxxxxxxx]: * Rebased to master. * The lookup_flags passed to sys_fchmodat4 as suggested by Al Viro. * Selftest added. Changes since v1 [20190531191204.4044-1-palmer@xxxxxxxxxx]: * All architectures are now supported, which support squashed into a single patch. * The do_fchmodat() helper function has been removed, in favor of directly calling do_fchmodat4(). * The patches are based on 5.2 instead of 5.1. --- Alexey Gladkov (2): fs: Add fchmodat2() selftests: Add fchmodat2 selftest Palmer Dabbelt (3): Non-functional cleanup of a "__user * filename" arch: Register fchmodat2, usually as syscall 452 tools headers UAPI: Sync files changed by new fchmodat2 syscall arch/alpha/kernel/syscalls/syscall.tbl | 1 + arch/arm/tools/syscall.tbl | 1 + arch/arm64/include/asm/unistd.h | 2 +- arch/arm64/include/asm/unistd32.h | 2 + arch/ia64/kernel/syscalls/syscall.tbl | 1 + arch/m68k/kernel/syscalls/syscall.tbl | 1 + arch/microblaze/kernel/syscalls/syscall.tbl | 1 + arch/mips/kernel/syscalls/syscall_n32.tbl | 1 + arch/mips/kernel/syscalls/syscall_n64.tbl | 1 + arch/mips/kernel/syscalls/syscall_o32.tbl | 1 + arch/parisc/kernel/syscalls/syscall.tbl | 1 + arch/powerpc/kernel/syscalls/syscall.tbl | 1 + arch/s390/kernel/syscalls/syscall.tbl | 1 + arch/sh/kernel/syscalls/syscall.tbl | 1 + arch/sparc/kernel/syscalls/syscall.tbl | 1 + arch/x86/entry/syscalls/syscall_32.tbl | 1 + arch/x86/entry/syscalls/syscall_64.tbl | 1 + arch/xtensa/kernel/syscalls/syscall.tbl | 1 + fs/open.c | 18 +- include/linux/syscalls.h | 4 +- include/uapi/asm-generic/unistd.h | 5 +- tools/include/uapi/asm-generic/unistd.h | 5 +- .../arch/mips/entry/syscalls/syscall_n64.tbl | 2 + .../arch/powerpc/entry/syscalls/syscall.tbl | 2 + .../perf/arch/s390/entry/syscalls/syscall.tbl | 2 + .../arch/x86/entry/syscalls/syscall_64.tbl | 2 + tools/testing/selftests/Makefile | 1 + tools/testing/selftests/fchmodat2/.gitignore | 2 + tools/testing/selftests/fchmodat2/Makefile | 6 + .../selftests/fchmodat2/fchmodat2_test.c | 162 ++++++++++++++++++ 30 files changed, 223 insertions(+), 8 deletions(-) create mode 100644 tools/testing/selftests/fchmodat2/.gitignore create mode 100644 tools/testing/selftests/fchmodat2/Makefile create mode 100644 tools/testing/selftests/fchmodat2/fchmodat2_test.c -- 2.33.8
