From: "Eric W. Biederman" <ebiederm@xmission.com>
To: Kees Cook <keescook@chromium.org>
Cc: "Robert Święcki" <robert@swiecki.net>,
stable@vger.kernel.org, "Andy Lutomirski" <luto@amacapital.net>,
"Will Drewry" <wad@chromium.org>,
linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH 1/3] signal: HANDLER_EXIT should clear SIGNAL_UNKILLABLE
Date: Thu, 10 Feb 2022 12:16:37 -0600 [thread overview]
Message-ID: <878rui8u4a.fsf@email.froward.int.ebiederm.org> (raw)
In-Reply-To: <20220210025321.787113-2-keescook@chromium.org> (Kees Cook's message of "Wed, 9 Feb 2022 18:53:19 -0800")
Kees Cook <keescook@chromium.org> writes:
> Fatal SIGSYS signals were not being delivered to pid namespace init
> processes . Make sure the SIGNAL_UNKILLABLE doesn't get set for these
^ when ptraced.
> cases.
Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>
I have pointed out a few nits in the wording but otherwise this looks good.
>
> 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>
> ---
> kernel/signal.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/signal.c b/kernel/signal.c
> index 38602738866e..33e3ee4f3383 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1342,9 +1342,10 @@ force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t,
> }
> /*
> * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
> - * debugging to leave init killable.
> + * debugging to leave init killable, unless it is intended to exit.
perhaps ^ 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);
Eric
next prev parent reply other threads:[~2022-02-10 18:16 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-10 2:53 [PATCH 0/3] signal: HANDLER_EXIT should clear SIGNAL_UNKILLABLE Kees Cook
2022-02-10 2:53 ` [PATCH 1/3] " Kees Cook
2022-02-10 16:18 ` Jann Horn
2022-02-10 17:37 ` Kees Cook
2022-02-10 18:01 ` Jann Horn
2022-02-10 18:12 ` Eric W. Biederman
2022-02-10 21:09 ` Kees Cook
2022-02-11 20:15 ` Jann Horn
2022-02-10 18:16 ` Eric W. Biederman [this message]
2022-02-10 2:53 ` [PATCH 2/3] seccomp: Invalidate seccomp mode to catch death failures Kees Cook
2022-02-10 2:53 ` [PATCH 3/3] samples/seccomp: Adjust sample to also provide kill option Kees Cook
2022-02-10 18:17 ` [PATCH 0/3] signal: HANDLER_EXIT should clear SIGNAL_UNKILLABLE Eric W. Biederman
2022-02-10 18:41 ` Kees Cook
2022-02-10 18:58 ` Eric W. Biederman
2022-02-10 20:43 ` Kees Cook
2022-02-10 22:48 ` Eric W. Biederman
2022-02-11 1:26 ` Kees Cook
2022-02-11 1:47 ` Eric W. Biederman
2022-02-11 2:53 ` Kees Cook
2022-02-11 12:54 ` Robert Święcki
2022-02-11 17:46 ` Eric W. Biederman
2022-02-11 18:57 ` Robert Święcki
2022-02-11 20:01 ` Kees Cook
2022-02-11 19:58 ` Kees Cook
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