diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2013-09-11 14:19:41 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-09-11 15:56:20 -0700 |
| commit | 40a0d32d1eaffe6aac7324ca92604b6b3977eb0e (patch) | |
| tree | c736993570ca2b16f0b7963226fda1947ec2c6b8 /kernel/fork.c | |
| parent | 5167246a8ad617df55717c2d901da5e2aedffcfa (diff) | |
| download | lwn-40a0d32d1eaffe6aac7324ca92604b6b3977eb0e.tar.gz lwn-40a0d32d1eaffe6aac7324ca92604b6b3977eb0e.zip | |
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 <oleg@redhat.com>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Colin Walters <walters@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 24 |
1 files changed, 9 insertions, 15 deletions
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) @@ -1576,15 +1579,6 @@ long do_fork(unsigned long clone_flags, 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 * requested, no event is reported; otherwise, report if the event |