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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 /security
parentb4ba35c75a0671a06b978b6386b54148efddf39f (diff)
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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 'security')
-rw-r--r--security/security.c6
-rw-r--r--security/selinux/hooks.c7
-rw-r--r--security/smack/smack_lsm.c20
3 files changed, 0 insertions, 33 deletions
diff --git a/security/security.c b/security/security.c
index 32052f5c76b2..8c9fee59e60a 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1025,11 +1025,6 @@ int security_task_kill(struct task_struct *p, struct siginfo *info,
return call_int_hook(task_kill, 0, p, info, sig, secid);
}
-int security_task_wait(struct task_struct *p)
-{
- return call_int_hook(task_wait, 0, p);
-}
-
int security_task_prctl(int option, unsigned long arg2, unsigned long arg3,
unsigned long arg4, unsigned long arg5)
{
@@ -1769,7 +1764,6 @@ struct security_hook_heads security_hook_heads = {
.task_movememory =
LIST_HEAD_INIT(security_hook_heads.task_movememory),
.task_kill = LIST_HEAD_INIT(security_hook_heads.task_kill),
- .task_wait = LIST_HEAD_INIT(security_hook_heads.task_wait),
.task_prctl = LIST_HEAD_INIT(security_hook_heads.task_prctl),
.task_to_inode =
LIST_HEAD_INIT(security_hook_heads.task_to_inode),
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 55ad878f1146..a5398fea0966 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3963,12 +3963,6 @@ static int selinux_task_kill(struct task_struct *p, struct siginfo *info,
return avc_has_perm(secid, task_sid(p), SECCLASS_PROCESS, perm, NULL);
}
-static int selinux_task_wait(struct task_struct *p)
-{
- return avc_has_perm(task_sid(p), current_sid(), SECCLASS_PROCESS,
- PROCESS__SIGCHLD, NULL);
-}
-
static void selinux_task_to_inode(struct task_struct *p,
struct inode *inode)
{
@@ -6211,7 +6205,6 @@ static struct security_hook_list selinux_hooks[] = {
LSM_HOOK_INIT(task_getscheduler, selinux_task_getscheduler),
LSM_HOOK_INIT(task_movememory, selinux_task_movememory),
LSM_HOOK_INIT(task_kill, selinux_task_kill),
- LSM_HOOK_INIT(task_wait, selinux_task_wait),
LSM_HOOK_INIT(task_to_inode, selinux_task_to_inode),
LSM_HOOK_INIT(ipc_permission, selinux_ipc_permission),
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 8da4a6b9ca4d..2166373ea5a4 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -2272,25 +2272,6 @@ static int smack_task_kill(struct task_struct *p, struct siginfo *info,
}
/**
- * smack_task_wait - Smack access check for waiting
- * @p: task to wait for
- *
- * Returns 0
- */
-static int smack_task_wait(struct task_struct *p)
-{
- /*
- * Allow the operation to succeed.
- * Zombies are bad.
- * In userless environments (e.g. phones) programs
- * get marked with SMACK64EXEC and even if the parent
- * and child shouldn't be talking the parent still
- * may expect to know when the child exits.
- */
- return 0;
-}
-
-/**
* smack_task_to_inode - copy task smack into the inode blob
* @p: task to copy from
* @inode: inode to copy to
@@ -4658,7 +4639,6 @@ static struct security_hook_list smack_hooks[] = {
LSM_HOOK_INIT(task_getscheduler, smack_task_getscheduler),
LSM_HOOK_INIT(task_movememory, smack_task_movememory),
LSM_HOOK_INIT(task_kill, smack_task_kill),
- LSM_HOOK_INIT(task_wait, smack_task_wait),
LSM_HOOK_INIT(task_to_inode, smack_task_to_inode),
LSM_HOOK_INIT(ipc_permission, smack_ipc_permission),