From: Kees Cook keescook@chromium.org
commit 5c72263ef2fbe99596848f03758ae2dc593adf2c upstream.
Fatal SIGSYS signals (i.e. seccomp RET_KILL_* syscall filter actions) were not being delivered to ptraced pid namespace init processes. Make sure the SIGNAL_UNKILLABLE doesn't get set for these cases.
Reported-by: Robert Święcki robert@swiecki.net Suggested-by: "Eric W. Biederman" ebiederm@xmission.com Fixes: 00b06da29cf9 ("signal: Add SA_IMMUTABLE to ensure forced siganls do not get changed") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook keescook@chromium.org Reviewed-by: "Eric W. Biederman" ebiederm@xmission.com Link: https://lore.kernel.org/lkml/878rui8u4a.fsf@email.froward.int.ebiederm.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/signal.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/kernel/signal.c +++ b/kernel/signal.c @@ -1339,9 +1339,10 @@ force_sig_info_to_task(struct kernel_sig } /* * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect - * debugging to leave init killable. + * debugging to leave init killable. But HANDLER_EXIT is always fatal. */ - if (action->sa.sa_handler == SIG_DFL && !t->ptrace) + if (action->sa.sa_handler == SIG_DFL && + (!t->ptrace || (handler == HANDLER_EXIT))) t->signal->flags &= ~SIGNAL_UNKILLABLE; ret = send_signal(sig, info, t, PIDTYPE_PID); spin_unlock_irqrestore(&t->sighand->siglock, flags);