From 40a0d32d1eaffe6aac7324ca92604b6b3977eb0e Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 11 Sep 2013 14:19:41 -0700 Subject: fork: unify and tighten up CLONE_NEWUSER/CLONE_NEWPID checks do_fork() denies CLONE_THREAD | CLONE_PARENT if NEWUSER | NEWPID. Then later copy_process() denies CLONE_SIGHAND if the new process will be in a different pid namespace (task_active_pid_ns() doesn't match current->nsproxy->pid_ns). This looks confusing and inconsistent. CLONE_NEWPID is very similar to the case when ->pid_ns was already unshared, we want the same restrictions so copy_process() should also nack CLONE_PARENT. And it would be better to deny CLONE_NEWUSER && CLONE_SIGHAND as well just for consistency. Kill the "CLONE_NEWUSER | CLONE_NEWPID" check in do_fork() and change copy_process() to do the same check along with ->pid_ns check we already have. Signed-off-by: Oleg Nesterov Acked-by: Andy Lutomirski Cc: "Eric W. Biederman" Cc: Colin Walters Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/fork.c | 24 +++++++++--------------- 1 file changed, 9 insertions(+), 15 deletions(-) (limited to 'kernel') diff --git a/kernel/fork.c b/kernel/fork.c index 68d508f2bfba..84703db06cf3 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1173,13 +1173,16 @@ static struct task_struct *copy_process(unsigned long clone_flags, return ERR_PTR(-EINVAL); /* - * If the new process will be in a different pid namespace don't - * allow it to share a thread group or signal handlers with the - * forking task. + * If the new process will be in a different pid or user namespace + * do not allow it to share a thread group or signal handlers or + * parent with the forking task. */ - if ((clone_flags & CLONE_SIGHAND) && (task_active_pid_ns(current) != - current->nsproxy->pid_ns_for_children)) - return ERR_PTR(-EINVAL); + if (clone_flags & (CLONE_SIGHAND | CLONE_PARENT)) { + if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) || + (task_active_pid_ns(current) != + current->nsproxy->pid_ns_for_children)) + return ERR_PTR(-EINVAL); + } retval = security_task_create(clone_flags); if (retval) @@ -1575,15 +1578,6 @@ long do_fork(unsigned long clone_flags, int trace = 0; long nr; - /* - * Do some preliminary argument and permissions checking before we - * actually start allocating stuff - */ - if (clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) { - if (clone_flags & (CLONE_THREAD|CLONE_PARENT)) - return -EINVAL; - } - /* * Determine whether and which event to report to ptracer. When * called from kernel_thread or CLONE_UNTRACED is explicitly -- cgit v1.2.3-59-g8ed1b