From: ebiederm@xmission.com (Eric W. Biederman) To: Oleg Nesterov <oleg@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org>, Aleksa Sarai <asarai@suse.com>, Andy Lutomirski <luto@amacapital.net>, Attila Fazekas <afazekas@redhat.com>, Jann Horn <jann@thejh.net>, Kees Cook <keescook@chromium.org>, Michal Hocko <mhocko@kernel.org>, Ulrich Obergfell <uobergfe@redhat.com>, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org Subject: [RFC][PATCH v2 5/5] signal: Don't allow accessing signal_struct by old threads after exec Date: Sun, 02 Apr 2017 17:57:46 -0500 [thread overview] Message-ID: <87zify76z9.fsf_-_@xmission.com> (raw) In-Reply-To: <874ly6a0h1.fsf_-_@xmission.com> (Eric W. Biederman's message of "Sun, 02 Apr 2017 17:50:02 -0500") Add exec_id to signal_struct and compare it at a few choice moments. I believe this closes the security holes that letting the zombie threads linger after exec opens up. The problem is that old threads may have different creds after a setuid exec, and then formerly shared resources may change. So signal sending and accesses by proc need to be blocked. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> --- fs/exec.c | 1 + include/linux/sched/signal.h | 1 + kernel/fork.c | 1 + kernel/ptrace.c | 4 ++++ kernel/signal.c | 7 ++++++- 5 files changed, 13 insertions(+), 1 deletion(-) diff --git a/fs/exec.c b/fs/exec.c index 303a114b00ce..730dee8bb2f8 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1323,6 +1323,7 @@ void setup_new_exec(struct linux_binprm * bprm) /* An exec changes our domain. We are no longer part of the thread group */ current->self_exec_id++; + current->signal->exec_id = current->self_exec_id; flush_signal_handlers(current, 0); } EXPORT_SYMBOL(setup_new_exec); diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 2cf446704cd4..63ae951ee330 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -80,6 +80,7 @@ struct signal_struct { atomic_t live; int nr_threads; struct list_head thread_head; + u32 exec_id; wait_queue_head_t wait_chldexit; /* for wait4() */ diff --git a/kernel/fork.c b/kernel/fork.c index 0632ac1180be..a442fa099842 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1387,6 +1387,7 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) sig->oom_score_adj = current->signal->oom_score_adj; sig->oom_score_adj_min = current->signal->oom_score_adj_min; + sig->exec_id = current->self_exec_id; mutex_init(&sig->cred_guard_mutex); diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 0af928712174..cc6b10b1ffbe 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -277,6 +277,10 @@ static int __ptrace_may_access(struct task_struct *task, unsigned int mode) * or halting the specified task is impossible. */ + /* Don't allow inspecting a thread after exec */ + if (task->self_exec_id != task->signal->exec_id) + return 1; + /* Don't let security modules deny introspection */ if (same_thread_group(task, current)) return 0; diff --git a/kernel/signal.c b/kernel/signal.c index fd75ba33ee3d..fe8dcdb622f5 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -995,6 +995,10 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t, from_ancestor_ns || (info == SEND_SIG_FORCED))) goto ret; + /* Don't allow thread group signals after exec */ + if (group && (t->signal->exec_id != t->self_exec_id)) + goto ret; + pending = group ? &t->signal->shared_pending : &t->pending; /* * Short-circuit ignored signals and support queuing @@ -1247,7 +1251,8 @@ struct sighand_struct *__lock_task_sighand(struct task_struct *tsk, * must see ->sighand == NULL. */ spin_lock(&sighand->siglock); - if (likely(sighand == tsk->sighand)) { + if (likely((sighand == tsk->sighand) && + (tsk->self_exec_id == tsk->signal->exec_id))) { rcu_read_unlock(); break; } -- 2.10.1
WARNING: multiple messages have this Message-ID (diff)
From: ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman) To: Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Cc: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, Aleksa Sarai <asarai-IBi9RG/b67k@public.gmane.org>, Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>, Attila Fazekas <afazekas-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Jann Horn <jann-XZ1E9jl8jIdeoWH0uzbU5w@public.gmane.org>, Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>, Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Ulrich Obergfell <uobergfe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Subject: [RFC][PATCH v2 5/5] signal: Don't allow accessing signal_struct by old threads after exec Date: Sun, 02 Apr 2017 17:57:46 -0500 [thread overview] Message-ID: <87zify76z9.fsf_-_@xmission.com> (raw) In-Reply-To: <874ly6a0h1.fsf_-_-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> (Eric W. Biederman's message of "Sun, 02 Apr 2017 17:50:02 -0500") Add exec_id to signal_struct and compare it at a few choice moments. I believe this closes the security holes that letting the zombie threads linger after exec opens up. The problem is that old threads may have different creds after a setuid exec, and then formerly shared resources may change. So signal sending and accesses by proc need to be blocked. Signed-off-by: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> --- fs/exec.c | 1 + include/linux/sched/signal.h | 1 + kernel/fork.c | 1 + kernel/ptrace.c | 4 ++++ kernel/signal.c | 7 ++++++- 5 files changed, 13 insertions(+), 1 deletion(-) diff --git a/fs/exec.c b/fs/exec.c index 303a114b00ce..730dee8bb2f8 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1323,6 +1323,7 @@ void setup_new_exec(struct linux_binprm * bprm) /* An exec changes our domain. We are no longer part of the thread group */ current->self_exec_id++; + current->signal->exec_id = current->self_exec_id; flush_signal_handlers(current, 0); } EXPORT_SYMBOL(setup_new_exec); diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 2cf446704cd4..63ae951ee330 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -80,6 +80,7 @@ struct signal_struct { atomic_t live; int nr_threads; struct list_head thread_head; + u32 exec_id; wait_queue_head_t wait_chldexit; /* for wait4() */ diff --git a/kernel/fork.c b/kernel/fork.c index 0632ac1180be..a442fa099842 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1387,6 +1387,7 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) sig->oom_score_adj = current->signal->oom_score_adj; sig->oom_score_adj_min = current->signal->oom_score_adj_min; + sig->exec_id = current->self_exec_id; mutex_init(&sig->cred_guard_mutex); diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 0af928712174..cc6b10b1ffbe 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -277,6 +277,10 @@ static int __ptrace_may_access(struct task_struct *task, unsigned int mode) * or halting the specified task is impossible. */ + /* Don't allow inspecting a thread after exec */ + if (task->self_exec_id != task->signal->exec_id) + return 1; + /* Don't let security modules deny introspection */ if (same_thread_group(task, current)) return 0; diff --git a/kernel/signal.c b/kernel/signal.c index fd75ba33ee3d..fe8dcdb622f5 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -995,6 +995,10 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t, from_ancestor_ns || (info == SEND_SIG_FORCED))) goto ret; + /* Don't allow thread group signals after exec */ + if (group && (t->signal->exec_id != t->self_exec_id)) + goto ret; + pending = group ? &t->signal->shared_pending : &t->pending; /* * Short-circuit ignored signals and support queuing @@ -1247,7 +1251,8 @@ struct sighand_struct *__lock_task_sighand(struct task_struct *tsk, * must see ->sighand == NULL. */ spin_lock(&sighand->siglock); - if (likely(sighand == tsk->sighand)) { + if (likely((sighand == tsk->sighand) && + (tsk->self_exec_id == tsk->signal->exec_id))) { rcu_read_unlock(); break; } -- 2.10.1
next prev parent reply other threads:[~2017-04-02 23:03 UTC|newest] Thread overview: 93+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-02-13 14:14 [PATCH 0/2] fix the traced mt-exec deadlock Oleg Nesterov 2017-02-13 14:15 ` [PATCH 1/2] exec: don't wait for zombie threads with cred_guard_mutex held Oleg Nesterov 2017-02-13 16:12 ` kbuild test robot 2017-02-13 16:47 ` Oleg Nesterov 2017-02-13 16:39 ` kbuild test robot 2017-02-13 17:27 ` Mika Penttilä 2017-02-13 18:01 ` Oleg Nesterov 2017-02-13 18:04 ` [PATCH V2 " Oleg Nesterov 2017-02-16 11:42 ` Eric W. Biederman 2017-02-20 15:22 ` Oleg Nesterov 2017-02-20 15:36 ` Oleg Nesterov 2017-02-20 22:30 ` Eric W. Biederman 2017-02-21 17:53 ` Oleg Nesterov 2017-02-21 20:20 ` Eric W. Biederman 2017-02-22 17:41 ` Oleg Nesterov 2017-02-17 4:42 ` Eric W. Biederman 2017-02-20 15:50 ` Oleg Nesterov 2017-02-13 14:15 ` [PATCH 2/2] ptrace: ensure PTRACE_EVENT_EXIT won't stop if the tracee is killed by exec Oleg Nesterov 2017-02-24 16:03 ` [PATCH 0/2] fix the traced mt-exec deadlock Oleg Nesterov 2017-03-03 1:05 ` Eric W. Biederman 2017-03-03 17:33 ` Oleg Nesterov 2017-03-03 18:23 ` Eric W. Biederman 2017-03-03 18:23 ` Eric W. Biederman 2017-03-03 18:59 ` Eric W. Biederman 2017-03-03 18:59 ` Eric W. Biederman 2017-03-03 20:06 ` Eric W. Biederman 2017-03-03 20:06 ` Eric W. Biederman 2017-03-03 20:11 ` [RFC][PATCH] exec: Don't wait for ptraced threads to be reaped Eric W. Biederman 2017-03-03 20:11 ` Eric W. Biederman 2017-03-04 17:03 ` Oleg Nesterov 2017-03-30 8:07 ` Eric W. Biederman 2017-04-01 5:11 ` [RFC][PATCH 0/2] exec: Fixing ptrace'd mulit-threaded hang Eric W. Biederman 2017-04-01 5:11 ` Eric W. Biederman 2017-04-01 5:14 ` [RFC][PATCH 1/2] sighand: Count each thread group once in sighand_struct Eric W. Biederman 2017-04-01 5:14 ` Eric W. Biederman 2017-04-01 5:16 ` [RFC][PATCH 2/2] exec: If possible don't wait for ptraced threads to be reaped Eric W. Biederman 2017-04-01 5:16 ` Eric W. Biederman 2017-04-02 15:35 ` Oleg Nesterov 2017-04-02 15:35 ` Oleg Nesterov 2017-04-02 18:53 ` Eric W. Biederman 2017-04-02 18:53 ` Eric W. Biederman 2017-04-03 18:12 ` Oleg Nesterov 2017-04-03 18:12 ` Oleg Nesterov 2017-04-03 21:04 ` Eric W. Biederman 2017-04-05 16:44 ` Oleg Nesterov 2017-04-02 15:38 ` [RFC][PATCH 0/2] exec: Fixing ptrace'd mulit-threaded hang Oleg Nesterov 2017-04-02 15:38 ` Oleg Nesterov 2017-04-02 22:50 ` [RFC][PATCH v2 0/5] " Eric W. Biederman 2017-04-02 22:50 ` Eric W. Biederman 2017-04-02 22:51 ` [RFC][PATCH v2 1/5] ptrace: Don't wait in PTRACE_O_TRACEEXIT for exec or coredump Eric W. Biederman 2017-04-02 22:51 ` Eric W. Biederman 2017-04-05 16:19 ` Oleg Nesterov 2017-04-02 22:51 ` [RFC][PATCH v2 2/5] sighand: Count each thread group once in sighand_struct Eric W. Biederman 2017-04-02 22:51 ` Eric W. Biederman 2017-04-02 22:52 ` [RFC][PATCH v2 3/5] clone: Disallown CLONE_THREAD with a shared sighand_struct Eric W. Biederman 2017-04-02 22:52 ` Eric W. Biederman 2017-04-05 16:24 ` Oleg Nesterov 2017-04-05 16:24 ` Oleg Nesterov 2017-04-05 17:34 ` Eric W. Biederman 2017-04-05 18:11 ` Oleg Nesterov 2017-04-02 22:53 ` [RFC][PATCH v2 4/5] exec: If possible don't wait for ptraced threads to be reaped Eric W. Biederman 2017-04-02 22:53 ` Eric W. Biederman 2017-04-05 16:15 ` Oleg Nesterov 2017-04-02 22:57 ` Eric W. Biederman [this message] 2017-04-02 22:57 ` [RFC][PATCH v2 5/5] signal: Don't allow accessing signal_struct by old threads after exec Eric W. Biederman 2017-04-05 16:18 ` Oleg Nesterov 2017-04-05 16:18 ` Oleg Nesterov 2017-04-05 18:16 ` Eric W. Biederman 2017-04-05 18:16 ` Eric W. Biederman 2017-04-06 15:48 ` Oleg Nesterov 2017-04-06 15:48 ` Oleg Nesterov 2017-04-02 16:15 ` [RFC][PATCH] exec: Don't wait for ptraced threads to be reaped Oleg Nesterov 2017-04-02 16:15 ` Oleg Nesterov 2017-04-02 21:07 ` Eric W. Biederman 2017-04-02 21:07 ` Eric W. Biederman 2017-04-03 18:37 ` Oleg Nesterov 2017-04-03 18:37 ` Oleg Nesterov 2017-04-03 22:49 ` Eric W. Biederman 2017-04-03 22:49 ` Eric W. Biederman 2017-04-03 22:49 ` scope of cred_guard_mutex Eric W. Biederman 2017-04-03 22:49 ` Eric W. Biederman 2017-04-05 16:08 ` Oleg Nesterov 2017-04-05 16:11 ` Kees Cook 2017-04-05 17:53 ` Eric W. Biederman 2017-04-05 18:15 ` Oleg Nesterov 2017-04-06 15:55 ` Oleg Nesterov 2017-04-06 15:55 ` Oleg Nesterov 2017-04-07 22:07 ` Kees Cook 2017-04-07 22:07 ` Kees Cook 2017-09-04 3:19 ` [RFC][PATCH] exec: Don't wait for ptraced threads to be reaped Robert O'Callahan 2017-09-04 3:19 ` Robert O'Callahan 2017-03-04 16:54 ` [PATCH 0/2] fix the traced mt-exec deadlock Oleg Nesterov 2017-03-04 16:54 ` Oleg Nesterov
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=87zify76z9.fsf_-_@xmission.com \ --to=ebiederm@xmission.com \ --cc=afazekas@redhat.com \ --cc=akpm@linux-foundation.org \ --cc=asarai@suse.com \ --cc=jann@thejh.net \ --cc=keescook@chromium.org \ --cc=linux-api@vger.kernel.org \ --cc=linux-kernel@vger.kernel.org \ --cc=luto@amacapital.net \ --cc=mhocko@kernel.org \ --cc=oleg@redhat.com \ --cc=uobergfe@redhat.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.