From: Oleg Nesterov <oleg@redhat.com>
To: Jann Horn <jann@thejh.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
Roland McGrath <roland@hack.frob.com>,
John Johansen <john.johansen@canonical.com>,
James Morris <james.l.morris@oracle.com>,
"Serge E. Hallyn" <serge@hallyn.com>,
Paul Moore <aul@paul-moore.com>,
Stephen Smalley <sds@tycho.nsa.gov>,
Eric Paris <eparis@parisplace.org>,
Casey Schaufler <casey@schaufler-ca.com>,
Kees Cook <keescook@chromium.org>,
Andrew Morton <akpm@linux-foundation.org>,
Janis Danisevskis <jdanis@google.com>,
Seth Forshee <seth.forshee@canonical.com>,
"Eric . Biederman" <ebiederm@xmission.com>,
Thomas Gleixner <tglx@linutronix.de>,
Benjamin LaHaise <bcrl@kvack.org>,
Ben Hutchings <ben@decadent.org.uk>,
Andy Lutomirski <luto@amacapital.net>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-fsdevel@vger.kernel.org,
linux-security-module@vger.kernel.org, security@kernel.org
Subject: Re: [PATCH v2 2/8] exec: turn self_exec_id into self_privunit
Date: Fri, 30 Sep 2016 15:20:47 +0200 [thread overview]
Message-ID: <20160930132046.GA12047@redhat.com> (raw)
In-Reply-To: <1474663238-22134-3-git-send-email-jann@thejh.net>
On 09/23, Jann Horn wrote:
>
> One reason for doing this is that it prevents an attacker from sending an
> arbitrary signal to a parent process after performing 2^32-1 execve()
> calls.
I think we should simply kill self/parent_exec_id's. I am going to send
the patch below after re-check/testing.
Oleg.
--- x/include/linux/sched.h
+++ x/include/linux/sched.h
@@ -1677,9 +1677,6 @@ struct task_struct {
#endif
struct seccomp seccomp;
-/* Thread group tracking */
- u32 parent_exec_id;
- u32 self_exec_id;
/* Protection of (de-)allocation: mm, files, fs, tty, keyrings, mems_allowed,
* mempolicy */
spinlock_t alloc_lock;
--- x/fs/exec.c
+++ x/fs/exec.c
@@ -1163,6 +1163,14 @@ static int de_thread(struct task_struct
no_thread_group:
/* we have changed execution domain */
tsk->exit_signal = SIGCHLD;
+ if (!list_empty(&father->children)) {
+ struct task_struct *child;
+
+ read_lock(&tasklist_lock);
+ list_for_each_entry(child, &father->children, sibling)
+ child->exit_signal = SIGCHLD;
+ read_unlock(&tasklist_lock);
+ }
exit_itimers(sig);
flush_itimer_signals();
@@ -1306,9 +1314,6 @@ void setup_new_exec(struct linux_binprm
set_dumpable(current->mm, suid_dumpable);
}
- /* An exec changes our domain. We are no longer part of the thread
- group */
- current->self_exec_id++;
flush_signal_handlers(current, 0);
do_close_on_exec(current->files);
}
--- x/kernel/fork.c
+++ x/kernel/fork.c
@@ -1573,13 +1573,10 @@ static struct task_struct *copy_process(
write_lock_irq(&tasklist_lock);
/* CLONE_PARENT re-uses the old parent */
- if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
+ if (clone_flags & (CLONE_PARENT|CLONE_THREAD))
p->real_parent = current->real_parent;
- p->parent_exec_id = current->parent_exec_id;
- } else {
+ else
p->real_parent = current;
- p->parent_exec_id = current->self_exec_id;
- }
spin_lock(¤t->sighand->siglock);
--- x/kernel/signal.c
+++ x/kernel/signal.c
@@ -1585,15 +1585,6 @@ bool do_notify_parent(struct task_struct
BUG_ON(!tsk->ptrace &&
(tsk->group_leader != tsk || !thread_group_empty(tsk)));
- if (sig != SIGCHLD) {
- /*
- * This is only possible if parent == real_parent.
- * Check if it has changed security domain.
- */
- if (tsk->parent_exec_id != tsk->parent->self_exec_id)
- sig = SIGCHLD;
- }
-
info.si_signo = sig;
info.si_errno = 0;
/*
next prev parent reply other threads:[~2016-09-30 13:22 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-23 20:40 [PATCH v2 0/8] Various fixes related to ptrace_may_access() Jann Horn
2016-09-23 20:40 ` [PATCH v2 1/8] exec: introduce cred_guard_light Jann Horn
2016-09-30 15:35 ` Oleg Nesterov
2016-09-30 18:27 ` Eric W. Biederman
2016-10-03 16:02 ` Oleg Nesterov
2016-10-30 21:12 ` Jann Horn
2016-09-23 20:40 ` [PATCH v2 2/8] exec: turn self_exec_id into self_privunit Jann Horn
2016-09-23 21:04 ` Andy Lutomirski
2016-09-23 21:33 ` Jann Horn
2016-09-30 13:20 ` Oleg Nesterov [this message]
2016-09-30 13:44 ` Oleg Nesterov
2016-09-30 18:30 ` Kees Cook
2016-09-30 18:59 ` Jann Horn
2016-09-30 19:05 ` Kees Cook
2016-10-03 16:37 ` Oleg Nesterov
2016-09-23 20:40 ` [PATCH v2 3/8] proc: use open()-time creds for ptrace checks Jann Horn
2016-09-23 20:40 ` [PATCH v2 4/8] futex: don't leak robust_list pointer Jann Horn
2016-09-30 14:52 ` Oleg Nesterov
2016-10-30 17:16 ` Jann Horn
2016-11-02 21:39 ` Jann Horn
2016-11-02 22:47 ` Jann Horn
2016-09-23 20:40 ` [PATCH v2 5/8] proc: lock properly in ptrace_may_access callers Jann Horn
2016-09-23 20:40 ` [PATCH v2 6/8] ptrace: warn on ptrace_may_access without proper locking Jann Horn
2016-09-23 20:40 ` [PATCH v2 7/8] fs/proc: fix attr access check Jann Horn
2016-09-23 20:40 ` [PATCH v2 8/8] Documentation: add security/ptrace_checks.txt Jann Horn
2016-10-02 3:16 ` Krister Johansen
2016-10-30 19:09 ` Jann Horn
2016-10-31 4:14 ` Eric W. Biederman
2016-10-31 13:39 ` Jann Horn
2016-11-03 20:43 ` Krister Johansen
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