Merge tag 'noinstr-x86-kvm-2020-05-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into HEAD

1 files changed, 26 insertions, 8 deletions

diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index dc8307bf2d74..beff0cfcd1e8 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -142,6 +142,7 @@ struct mqueue_inode_info {
 
 	struct sigevent notify;
 	struct pid *notify_owner;
+	u32 notify_self_exec_id;
 	struct user_namespace *notify_user_ns;
 	struct user_struct *user;	/* user who created, for accounting */
 	struct sock *notify_sock;
@@ -773,28 +774,44 @@ static void __do_notify(struct mqueue_inode_info *info)
 	 * synchronously. */
 	if (info->notify_owner &&
 	    info->attr.mq_curmsgs == 1) {
-		struct kernel_siginfo sig_i;
 		switch (info->notify.sigev_notify) {
 		case SIGEV_NONE:
 			break;
-		case SIGEV_SIGNAL:
-			/* sends signal */
+		case SIGEV_SIGNAL: {
+			struct kernel_siginfo sig_i;
+			struct task_struct *task;
+
+			/* do_mq_notify() accepts sigev_signo == 0, why?? */
+			if (!info->notify.sigev_signo)
+				break;
 
 			clear_siginfo(&sig_i);
 			sig_i.si_signo = info->notify.sigev_signo;
 			sig_i.si_errno = 0;
 			sig_i.si_code = SI_MESGQ;
 			sig_i.si_value = info->notify.sigev_value;
-			/* map current pid/uid into info->owner's namespaces */
 			rcu_read_lock();
+			/* map current pid/uid into info->owner's namespaces */
 			sig_i.si_pid = task_tgid_nr_ns(current,
 						ns_of_pid(info->notify_owner));
-			sig_i.si_uid = from_kuid_munged(info->notify_user_ns, current_uid());
+			sig_i.si_uid = from_kuid_munged(info->notify_user_ns,
+						current_uid());
+			/*
+			 * We can't use kill_pid_info(), this signal should
+			 * bypass check_kill_permission(). It is from kernel
+			 * but si_fromuser() can't know this.
+			 * We do check the self_exec_id, to avoid sending
+			 * signals to programs that don't expect them.
+			 */
+			task = pid_task(info->notify_owner, PIDTYPE_TGID);
+			if (task && task->self_exec_id ==
+						info->notify_self_exec_id) {
+				do_send_sig_info(info->notify.sigev_signo,
+						&sig_i, task, PIDTYPE_TGID);
+			}
 			rcu_read_unlock();
-
-			kill_pid_info(info->notify.sigev_signo,
-				      &sig_i, info->notify_owner);
 			break;
+		}
 		case SIGEV_THREAD:
 			set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
 			netlink_sendskb(info->notify_sock, info->notify_cookie);
@@ -1383,6 +1400,7 @@ retry:
 			info->notify.sigev_signo = notification->sigev_signo;
 			info->notify.sigev_value = notification->sigev_value;
 			info->notify.sigev_notify = SIGEV_SIGNAL;
+			info->notify_self_exec_id = current->self_exec_id;
 			break;
 		}