From 3a2f5a59a695a73e0cde9a61e0feae5fa730e936 Mon Sep 17 00:00:00 2001 From: Stephen Smalley Date: Tue, 10 Jan 2017 12:28:32 -0500 Subject: security,selinux,smack: kill security_task_wait hook As reported by yangshukui, a permission denial from security_task_wait() can lead to a soft lockup in zap_pid_ns_processes() since it only expects sys_wait4() to return 0 or -ECHILD. Further, security_task_wait() can in general lead to zombies; in the absence of some way to automatically reparent a child process upon a denial, the hook is not useful. Remove the security hook and its implementations in SELinux and Smack. Smack already removed its check from its hook. Reported-by: yangshukui Signed-off-by: Stephen Smalley Acked-by: Casey Schaufler Acked-by: Oleg Nesterov Signed-off-by: Paul Moore --- kernel/exit.c | 19 ++----------------- 1 file changed, 2 insertions(+), 17 deletions(-) (limited to 'kernel/exit.c') diff --git a/kernel/exit.c b/kernel/exit.c index 8f14b866f9f6..60f245190571 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -14,7 +14,6 @@ #include #include #include -#include #include #include #include @@ -1360,7 +1359,7 @@ static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) * Returns nonzero for a final return, when we have unlocked tasklist_lock. * Returns zero if the search for a child should continue; * then ->notask_error is 0 if @p is an eligible child, - * or another error from security_task_wait(), or still -ECHILD. + * or still -ECHILD. */ static int wait_consider_task(struct wait_opts *wo, int ptrace, struct task_struct *p) @@ -1380,20 +1379,6 @@ static int wait_consider_task(struct wait_opts *wo, int ptrace, if (!ret) return ret; - ret = security_task_wait(p); - if (unlikely(ret < 0)) { - /* - * If we have not yet seen any eligible child, - * then let this error code replace -ECHILD. - * A permission error will give the user a clue - * to look for security policy problems, rather - * than for mysterious wait bugs. - */ - if (wo->notask_error) - wo->notask_error = ret; - return 0; - } - if (unlikely(exit_state == EXIT_TRACE)) { /* * ptrace == 0 means we are the natural parent. In this case @@ -1486,7 +1471,7 @@ static int wait_consider_task(struct wait_opts *wo, int ptrace, * Returns nonzero for a final return, when we have unlocked tasklist_lock. * Returns zero if the search for a child should continue; then * ->notask_error is 0 if there were any eligible children, - * or another error from security_task_wait(), or still -ECHILD. + * or still -ECHILD. */ static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk) { -- cgit