8382fcac "pidns: Outlaw thread creation after unshare(CLONE_NEWPID)"
nacks CLONE_NEWPID if the forking process unshared pid_ns. This is
correct but unnecessary, copy_pid_ns() does the same check.
Test-case (needs root or CLONE_NEWUSER should be added):
static int child(void *arg)
{
return 0;
}
static char stack[16 * 1024];
int main(void)
{
pid_t pid;
assert(unshare(CLONE_NEWPID) == 0);
pid = clone(child, stack + sizeof(stack) / 2,
CLONE_NEWPID | SIGCHLD, NULL);
assert(pid < 0 && errno == EINVAL);
return 0;
}
clone(CLONE_NEWPID) correctly fails with or without this change.
Signed-off-by: Oleg Nesterov <o...@redhat.com>
---
kernel/fork.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/fork.c b/kernel/fork.c
index 86f5376..8d56338 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1176,7 +1176,7 @@ static struct task_struct *copy_process(unsigned long
clone_flags,
* If the new process will be in a different pid namespace don't
* allow the creation of threads, or share the signal handlers.
*/
- if ((clone_flags & (CLONE_SIGHAND | CLONE_NEWPID)) &&
+ if ((clone_flags & CLONE_SIGHAND) &&
(task_active_pid_ns(current) != current->nsproxy->pid_ns))
return ERR_PTR(-EINVAL);
--
1.5.5.1
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