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m68k: Fix seccomp filtering on ColdFire and 68000

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m68k selects HAVE_ARCH_SECCOMP_FILTER for all configurations, but the
ColdFire and 68000 syscall entry paths only branch to
syscall_trace_enter() for TIF_SYSCALL_TRACE. TIF_SECCOMP alone falls
through to syscall dispatch, leaving installed filters ineffective.

Test the combined TIF_SYSCALL_TRACE and TIF_SECCOMP mask in both paths
and route either flag through the existing slow path. Leave the classic
MMU syscall entry implementation unchanged.

Validated the combined test under QEMU mcf5208evb (ColdFire): filters
denying getpid, openat, unlinkat, and reboot each returned -EPERM. A
classic-MMU control (q800) denied the filtered getpid syscall both before
and after this change. The 68000 path shares the same source-level
omission and receives the identical masked test but was not separately
emulated. Compile-tested W=1 with CONFIG_SECCOMP_FILTER=y on both
m5208evb_defconfig and a custom no-MMU UCSIMM configuration; the latter
built arch/m68k/68000/entry.o and vmlinux.

Fixes: 6baaade155 ("m68k: Add kernel seccomp support")
Cc: stable@vger.kernel.org # v6.3+
Suggested-by: Andreas Schwab <schwab@linux-m68k.org>
Assisted-by: Claude:claude-opus-4-8
Assisted-by: Codex:gpt-5.6-sol
Signed-off-by: Christopher Lusk <clusk@northecho.dev>
Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>
This commit is contained in:
Christopher Lusk 2026-09-13 09:17:53 -04:00 committed by Greg Ungerer
parent 39e5ca862b
commit 48859f8018
2 changed files with 4 additions and 2 deletions
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3
arch/m68k/68000/entry.S
View File

@ -79,7 +79,8 @@ ENTRY(system_call)
/* Doing a trace ? */
getthreadinfo
btst #(TIF_SYSCALL_TRACE%8),%a2@(TINFO_FLAGS+(31-TIF_SYSCALL_TRACE)/8)
moveb %a2@(TINFO_FLAGS+2),%d1
andl #((_TIF_SYSCALL_TRACE + _TIF_SECCOMP) >> 8),%d1
jne do_trace
cmpl #NR_syscalls,%d0
jcc badsys

3
arch/m68k/coldfire/entry.S
View File

@ -72,7 +72,8 @@ ENTRY(system_call)
movel %d2,%a0
movel %a0@,%a1 /* save top of frame */
movel %sp,%a1@(TASK_THREAD+THREAD_ESP0)
btst #(TIF_SYSCALL_TRACE%8),%a0@(TINFO_FLAGS+(31-TIF_SYSCALL_TRACE)/8)
moveb %a0@(TINFO_FLAGS+2),%d2
andl #((_TIF_SYSCALL_TRACE + _TIF_SECCOMP) >> 8),%d2
bnes 1f
movel %d3,%a0