seccomp: move arch_prctl to @default

keszybz · keszybz · commit 5f02870a74aa · 2022-01-07T17:34:17.000+01:00
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 systemd#22033.
diff --git a/src/shared/seccomp-util.c b/src/shared/seccomp-util.c
@@ -286,6 +286,7 @@ 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"
@@ -715,7 +716,6 @@ 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"
