--- /dev/null
+From 3a2f5a59a695a73e0cde9a61e0feae5fa730e936 Mon Sep 17 00:00:00 2001
+From: Stephen Smalley <sds@tycho.nsa.gov>
+Date: Tue, 10 Jan 2017 12:28:32 -0500
+Subject: security,selinux,smack: kill security_task_wait hook
+
+From: Stephen Smalley <sds@tycho.nsa.gov>
+
+commit 3a2f5a59a695a73e0cde9a61e0feae5fa730e936 upstream.
+
+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>
+Signed-off-by: Alexander Grund <theflamefire89@gmail.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ include/linux/lsm_hooks.h | 7 -------
+ include/linux/security.h | 6 ------
+ kernel/exit.c | 19 ++-----------------
+ security/security.c | 6 ------
+ security/selinux/hooks.c | 6 ------
+ security/smack/smack_lsm.c | 20 --------------------
+ 6 files changed, 2 insertions(+), 62 deletions(-)
+
+--- a/include/linux/lsm_hooks.h
++++ b/include/linux/lsm_hooks.h
+@@ -666,11 +666,6 @@
+ * @sig contains the signal value.
+ * @secid contains the sid of the process where the signal originated
+ * Return 0 if permission is granted.
+- * @task_wait:
+- * Check permission before allowing a process to reap a child process @p
+- * and collect its status information.
+- * @p contains the task_struct for process.
+- * Return 0 if permission is granted.
+ * @task_prctl:
+ * Check permission before performing a process control operation on the
+ * current process.
+@@ -1507,7 +1502,6 @@ union security_list_options {
+ int (*task_movememory)(struct task_struct *p);
+ int (*task_kill)(struct task_struct *p, struct siginfo *info,
+ int sig, u32 secid);
+- int (*task_wait)(struct task_struct *p);
+ int (*task_prctl)(int option, unsigned long arg2, unsigned long arg3,
+ unsigned long arg4, unsigned long arg5);
+ void (*task_to_inode)(struct task_struct *p, struct inode *inode);
+@@ -1768,7 +1762,6 @@ struct security_hook_heads {
+ struct list_head task_getscheduler;
+ struct list_head task_movememory;
+ struct list_head task_kill;
+- struct list_head task_wait;
+ struct list_head task_prctl;
+ struct list_head task_to_inode;
+ struct list_head ipc_permission;
+--- a/include/linux/security.h
++++ b/include/linux/security.h
+@@ -332,7 +332,6 @@ int security_task_getscheduler(struct ta
+ int security_task_movememory(struct task_struct *p);
+ int security_task_kill(struct task_struct *p, struct siginfo *info,
+ int sig, u32 secid);
+-int security_task_wait(struct task_struct *p);
+ int security_task_prctl(int option, unsigned long arg2, unsigned long arg3,
+ unsigned long arg4, unsigned long arg5);
+ void security_task_to_inode(struct task_struct *p, struct inode *inode);
+@@ -979,11 +978,6 @@ static inline int security_task_kill(str
+ {
+ return 0;
+ }
+-
+-static inline int security_task_wait(struct task_struct *p)
+-{
+- return 0;
+-}
+
+ static inline int security_task_prctl(int option, unsigned long arg2,
+ unsigned long arg3,
+--- 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>
+@@ -1342,7 +1341,7 @@ static int wait_task_continued(struct wa
+ * 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)
+@@ -1362,20 +1361,6 @@ static int wait_consider_task(struct wai
+ 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
+@@ -1468,7 +1453,7 @@ static int wait_consider_task(struct wai
+ * 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)
+ {
+--- a/security/security.c
++++ b/security/security.c
+@@ -1032,11 +1032,6 @@ int security_task_kill(struct task_struc
+ 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)
+ {
+@@ -1776,7 +1771,6 @@ struct security_hook_heads security_hook
+ .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),
+--- a/security/selinux/hooks.c
++++ b/security/selinux/hooks.c
+@@ -3951,11 +3951,6 @@ static int selinux_task_kill(struct task
+ return rc;
+ }
+
+-static int selinux_task_wait(struct task_struct *p)
+-{
+- return task_has_perm(p, current, PROCESS__SIGCHLD);
+-}
+-
+ static void selinux_task_to_inode(struct task_struct *p,
+ struct inode *inode)
+ {
+@@ -6220,7 +6215,6 @@ static struct security_hook_list selinux
+ 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),
+--- a/security/smack/smack_lsm.c
++++ b/security/smack/smack_lsm.c
+@@ -2277,25 +2277,6 @@ static int smack_task_kill(struct task_s
+ }
+
+ /**
+- * 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
+@@ -4686,7 +4667,6 @@ static struct security_hook_list smack_h
+ 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),
projects / thirdparty / kernel / stable-queue.git / commitdiff
