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authorStephen Smalley <sds@tycho.nsa.gov>2017-01-10 12:28:32 -0500
committerPaul Moore <paul@paul-moore.com>2017-01-12 11:10:57 -0500
commit3a2f5a59a695a73e0cde9a61e0feae5fa730e936 (patch)
tree058704d18e909a2c0b46356c74d3c1156c2206aa /kernel/exit.c
parentb4ba35c75a0671a06b978b6386b54148efddf39f (diff)
downloadlinux-3a2f5a59a695a73e0cde9a61e0feae5fa730e936.tar.bz2
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 <yangshukui@huawei.com> Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> Acked-by: Casey Schaufler <casey@schaufler-ca.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
Diffstat (limited to 'kernel/exit.c')
-rw-r--r--kernel/exit.c19
1 files changed, 2 insertions, 17 deletions
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 <linux/tty.h>
#include <linux/iocontext.h>
#include <linux/key.h>
-#include <linux/security.h>
#include <linux/cpu.h>
#include <linux/acct.h>
#include <linux/tsacct_kern.h>
@@ -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)
{