From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AF2F9C282CE for ; Thu, 23 May 2019 00:40:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 63A8F20B1F for ; Thu, 23 May 2019 00:40:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729594AbfEWAkN (ORCPT ); Wed, 22 May 2019 20:40:13 -0400 Received: from out02.mta.xmission.com ([166.70.13.232]:57239 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727790AbfEWAkN (ORCPT ); Wed, 22 May 2019 20:40:13 -0400 Received: from in01.mta.xmission.com ([166.70.13.51]) by out02.mta.xmission.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.87) (envelope-from ) id 1hTbmF-00087u-DY; Wed, 22 May 2019 18:40:11 -0600 Received: from ip72-206-97-68.om.om.cox.net ([72.206.97.68] helo=x220.int.ebiederm.org) by in01.mta.xmission.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_CBC_SHA256:128) (Exim 4.87) (envelope-from ) id 1hTbmD-0005Z3-E5; Wed, 22 May 2019 18:40:11 -0600 From: "Eric W. Biederman" To: linux-kernel@vger.kernel.org Cc: "Eric W. Biederman" , Linux Containers , Oleg Nesterov , linux-arch@vger.kernel.org Date: Wed, 22 May 2019 19:38:51 -0500 Message-Id: <20190523003916.20726-2-ebiederm@xmission.com> X-Mailer: git-send-email 2.21.0.dirty In-Reply-To: <20190523003916.20726-1-ebiederm@xmission.com> References: <20190523003916.20726-1-ebiederm@xmission.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-XM-SPF: eid=1hTbmD-0005Z3-E5;;;mid=<20190523003916.20726-2-ebiederm@xmission.com>;;;hst=in01.mta.xmission.com;;;ip=72.206.97.68;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1+oLSyth5cPdfAB5jZdENZxJdpgNbS/kZE= X-SA-Exim-Connect-IP: 72.206.97.68 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: [REVIEW][PATCH 01/26] signal: Correct namespace fixups of si_pid and si_uid X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The function send_signal was split from __send_signal so that it would be possible to bypass the namespace logic based upon current[1]. As it turns out the si_pid and the si_uid fixup are both inappropriate in the case of kill_pid_usb_asyncio so move that logic into send_signal. It is difficult to arrange but possible for a signal with an si_code of SI_TIMER or SI_SIGIO to be sent across namespace boundaries. In which case tests for when it is ok to change si_pid and si_uid based on SI_FROMUSER are incorrect. Replace the use of SI_FROMUSER with a new test has_si_pid_and_used based on siginfo_layout. Now that the uid fixup is no longer present after expanding SEND_SIG_NOINFO properly calculate the si_uid that the target task needs to read. [1] 7978b567d315 ("signals: add from_ancestor_ns parameter to send_signal()") Cc: stable@vger.kernel.org Fixes: 6588c1e3ff01 ("signals: SI_USER: Masquerade si_pid when crossing pid ns boundary") Fixes: 6b550f949594 ("user namespace: make signal.c respect user namespaces") Signed-off-by: "Eric W. Biederman" --- kernel/signal.c | 67 +++++++++++++++++++++++++++++-------------------- 1 file changed, 40 insertions(+), 27 deletions(-) diff --git a/kernel/signal.c b/kernel/signal.c index 18040d6bd63a..39a3eca5ce22 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1056,27 +1056,6 @@ static inline bool legacy_queue(struct sigpending *signals, int sig) return (sig < SIGRTMIN) && sigismember(&signals->signal, sig); } -#ifdef CONFIG_USER_NS -static inline void userns_fixup_signal_uid(struct kernel_siginfo *info, struct task_struct *t) -{ - if (current_user_ns() == task_cred_xxx(t, user_ns)) - return; - - if (SI_FROMKERNEL(info)) - return; - - rcu_read_lock(); - info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns), - make_kuid(current_user_ns(), info->si_uid)); - rcu_read_unlock(); -} -#else -static inline void userns_fixup_signal_uid(struct kernel_siginfo *info, struct task_struct *t) -{ - return; -} -#endif - static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t, enum pid_type type, int from_ancestor_ns) { @@ -1134,7 +1113,11 @@ static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struc q->info.si_code = SI_USER; q->info.si_pid = task_tgid_nr_ns(current, task_active_pid_ns(t)); - q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid()); + rcu_read_lock(); + q->info.si_uid = + from_kuid_munged(task_cred_xxx(t, user_ns), + current_uid()); + rcu_read_unlock(); break; case (unsigned long) SEND_SIG_PRIV: clear_siginfo(&q->info); @@ -1146,13 +1129,8 @@ static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struc break; default: copy_siginfo(&q->info, info); - if (from_ancestor_ns) - q->info.si_pid = 0; break; } - - userns_fixup_signal_uid(&q->info, t); - } else if (!is_si_special(info)) { if (sig >= SIGRTMIN && info->si_code != SI_USER) { /* @@ -1196,6 +1174,28 @@ static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struc return ret; } +static inline bool has_si_pid_and_uid(struct kernel_siginfo *info) +{ + bool ret = false; + switch (siginfo_layout(info->si_signo, info->si_code)) { + case SIL_KILL: + case SIL_CHLD: + case SIL_RT: + ret = true; + break; + case SIL_TIMER: + case SIL_POLL: + case SIL_FAULT: + case SIL_FAULT_MCEERR: + case SIL_FAULT_BNDERR: + case SIL_FAULT_PKUERR: + case SIL_SYS: + ret = false; + break; + } + return ret; +} + static int send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t, enum pid_type type) { @@ -1205,7 +1205,20 @@ static int send_signal(int sig, struct kernel_siginfo *info, struct task_struct from_ancestor_ns = si_fromuser(info) && !task_pid_nr_ns(current, task_active_pid_ns(t)); #endif + if (!is_si_special(info) && has_si_pid_and_uid(info)) { + struct user_namespace *t_user_ns; + rcu_read_lock(); + t_user_ns = task_cred_xxx(t, user_ns); + if (current_user_ns() != t_user_ns) { + kuid_t uid = make_kuid(current_user_ns(), info->si_uid); + info->si_uid = from_kuid_munged(t_user_ns, uid); + } + rcu_read_unlock(); + + if (!task_pid_nr_ns(current, task_active_pid_ns(t))) + info->si_pid = 0; + } return __send_signal(sig, info, t, type, from_ancestor_ns); } -- 2.21.0