seccomp: move arch_prctl to @default

It was reported as used by the linker:

> [It is] called in the setup of ld-linux-x86-64.so.2 from _dl_sysdep_start.
> My local call stack (with LTO):
>
> #0 init_cpu_features.constprop.0 (/usr/lib64/ld-linux-x86-64.so.2)
> #1 _dl_sysdep_start (/usr/lib64/ld-linux-x86-64.so.2)
> #2 _dl_start (/usr/lib64/ld-linux-x86-64.so.2)
> #3 _start (/usr/lib64/ld-linux-x86-64.so.2)
>
> Looking through the source, I think it's this (links for glibc 2.34):
> - First dl_platform_init calls _dl_x86_init_cpu_features, a wrapper for init_cpu_features.
> - Then init_cpu_features calls get_cet_status.
> - At last, get_cet_status invokes arch_prctl.

Fixes #22033.

(cherry picked from commit 5f02870a74aa3a758115cc9bd6d68f239caf8453)
(cherry picked from commit d08f6ff204c8525f7533875128468afb8be60ae0)

diff --git a/src/shared/seccomp-util.c b/src/shared/seccomp-util.c
index 2d73354e1a548c3b982866b557482a8a10111b42..ccfa4cc56a18a427353cd587d1f468fcba8d19be 100644 (file)
--- a/src/shared/seccomp-util.c
+++ b/src/shared/seccomp-util.c
@@ -283,6 +283,7 @@ const SyscallFilterSet syscall_filter_sets[_SYSCALL_FILTER_SET_MAX] = {
                 .name = "@default",
                 .help = "System calls that are always permitted",
                 .value =
+                "arch_prctl\0"      /* Used during platform-specific initialization by ld-linux.so. */
                 "brk\0"
                 "cacheflush\0"
                 "clock_getres\0"
@@ -712,7 +713,6 @@ const SyscallFilterSet syscall_filter_sets[_SYSCALL_FILTER_SET_MAX] = {
                 .name = "@process",
                 .help = "Process control, execution, namespacing operations",
                 .value =
-                "arch_prctl\0"
                 "capget\0"      /* Able to query arbitrary processes */
                 "clone\0"
                 "clone3\0"