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c5efa393d8
The new signal_scoping_thread_setuid tests check that the libc's
setuid() function works as expected even when a thread is sandboxed with
scoped signal restrictions.
Before the signal scoping fix, this test would have failed with the
setuid() call:
[pid 65] getpid() = 65
[pid 65] tgkill(65, 66, SIGRT_1) = -1 EPERM (Operation not permitted)
[pid 65] futex(0x40a66cdc, FUTEX_WAKE_PRIVATE, 1) = 0
[pid 65] setuid(1001) = 0
After the fix, tgkill(2) is successfully leveraged to synchronize
credentials update across threads:
[pid 65] getpid() = 65
[pid 65] tgkill(65, 66, SIGRT_1) = 0
[pid 66] <... read resumed>0x40a65eb7, 1) = ? ERESTARTSYS (To be restarted if SA_RESTART is set)
[pid 66] --- SIGRT_1 {si_signo=SIGRT_1, si_code=SI_TKILL, si_pid=65, si_uid=1000} ---
[pid 66] getpid() = 65
[pid 66] setuid(1001) = 0
[pid 66] futex(0x40a66cdc, FUTEX_WAKE_PRIVATE, 1) = 0
[pid 66] rt_sigreturn({mask=[]}) = 0
[pid 66] read(3, <unfinished ...>
[pid 65] setuid(1001) = 0
Test coverage for security/landlock is 92.9% of 1137 lines according to
gcc/gcov-14.
Fixes: c899496501 ("selftests/landlock: Test signal scoping for threads")
Cc: Günther Noack <gnoack@google.com>
Cc: Tahera Fahimi <fahimitahera@gmail.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250318161443.279194-8-mic@digikod.net
[mic: Update test coverage]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Linux kernel
============
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In order to build the documentation, use ``make htmldocs`` or
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