1 files changed, 111 insertions, 25 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 206551563cce..17afcaf582d0 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -28,6 +28,7 @@
 #include <linux/freezer.h>
 #include <linux/pid_namespace.h>
 #include <linux/nsproxy.h>
+#include <linux/user_namespace.h>
 #define CREATE_TRACE_POINTS
 #include <trace/events/signal.h>
 
@@ -35,6 +36,7 @@
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
 #include <asm/siginfo.h>
+#include <asm/cacheflush.h>
 #include "audit.h"	/* audit_signal_info() */
 
 /*
@@ -57,21 +59,20 @@ static int sig_handler_ignored(void __user *handler, int sig)
 		(handler == SIG_DFL && sig_kernel_ignore(sig));
 }
 
-static int sig_task_ignored(struct task_struct *t, int sig,
-		int from_ancestor_ns)
+static int sig_task_ignored(struct task_struct *t, int sig, bool force)
 {
 	void __user *handler;
 
 	handler = sig_handler(t, sig);
 
 	if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
-			handler == SIG_DFL && !from_ancestor_ns)
+			handler == SIG_DFL && !force)
 		return 1;
 
 	return sig_handler_ignored(handler, sig);
 }
 
-static int sig_ignored(struct task_struct *t, int sig, int from_ancestor_ns)
+static int sig_ignored(struct task_struct *t, int sig, bool force)
 {
 	/*
 	 * Blocked signals are never ignored, since the
@@ -81,7 +82,7 @@ static int sig_ignored(struct task_struct *t, int sig, int from_ancestor_ns)
 	if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
 		return 0;
 
-	if (!sig_task_ignored(t, sig, from_ancestor_ns))
+	if (!sig_task_ignored(t, sig, force))
 		return 0;
 
 	/*
@@ -854,7 +855,7 @@ static void ptrace_trap_notify(struct task_struct *t)
  * Returns true if the signal should be actually delivered, otherwise
  * it should be dropped.
  */
-static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns)
+static int prepare_signal(int sig, struct task_struct *p, bool force)
 {
 	struct signal_struct *signal = p->signal;
 	struct task_struct *t;
@@ -914,7 +915,7 @@ static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns)
 		}
 	}
 
-	return !sig_ignored(p, sig, from_ancestor_ns);
+	return !sig_ignored(p, sig, force);
 }
 
 /*
@@ -1019,19 +1020,48 @@ static inline int legacy_queue(struct sigpending *signals, int sig)
 	return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
 }
 
+/*
+ * map the uid in struct cred into user namespace *ns
+ */
+static inline uid_t map_cred_ns(const struct cred *cred,
+				struct user_namespace *ns)
+{
+	return user_ns_map_uid(ns, cred, cred->uid);
+}
+
+#ifdef CONFIG_USER_NS
+static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
+{
+	if (current_user_ns() == task_cred_xxx(t, user_ns))
+		return;
+
+	if (SI_FROMKERNEL(info))
+		return;
+
+	info->si_uid = user_ns_map_uid(task_cred_xxx(t, user_ns),
+					current_cred(), info->si_uid);
+}
+#else
+static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
+{
+	return;
+}
+#endif
+
 static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
 			int group, int from_ancestor_ns)
 {
 	struct sigpending *pending;
 	struct sigqueue *q;
 	int override_rlimit;
-
-	trace_signal_generate(sig, info, t);
+	int ret = 0, result;
 
 	assert_spin_locked(&t->sighand->siglock);
 
-	if (!prepare_signal(sig, t, from_ancestor_ns))
-		return 0;
+	result = TRACE_SIGNAL_IGNORED;
+	if (!prepare_signal(sig, t,
+			from_ancestor_ns || (info == SEND_SIG_FORCED)))
+		goto ret;
 
 	pending = group ? &t->signal->shared_pending : &t->pending;
 	/*
@@ -1039,8 +1069,11 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
 	 * exactly one non-rt signal, so that we can get more
 	 * detailed information about the cause of the signal.
 	 */
+	result = TRACE_SIGNAL_ALREADY_PENDING;
 	if (legacy_queue(pending, sig))
-		return 0;
+		goto ret;
+
+	result = TRACE_SIGNAL_DELIVERED;
 	/*
 	 * fast-pathed signals for kernel-internal things like SIGSTOP
 	 * or SIGKILL.
@@ -1088,6 +1121,9 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
 				q->info.si_pid = 0;
 			break;
 		}
+
+		userns_fixup_signal_uid(&q->info, t);
+
 	} else if (!is_si_special(info)) {
 		if (sig >= SIGRTMIN && info->si_code != SI_USER) {
 			/*
@@ -1095,14 +1131,15 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
 			 * signal was rt and sent by user using something
 			 * other than kill().
 			 */
-			trace_signal_overflow_fail(sig, group, info);
-			return -EAGAIN;
+			result = TRACE_SIGNAL_OVERFLOW_FAIL;
+			ret = -EAGAIN;
+			goto ret;
 		} else {
 			/*
 			 * This is a silent loss of information.  We still
 			 * send the signal, but the *info bits are lost.
 			 */
-			trace_signal_lose_info(sig, group, info);
+			result = TRACE_SIGNAL_LOSE_INFO;
 		}
 	}
 
@@ -1110,7 +1147,9 @@ out_set:
 	signalfd_notify(t, sig);
 	sigaddset(&pending->signal, sig);
 	complete_signal(sig, t, group);
-	return 0;
+ret:
+	trace_signal_generate(sig, info, t, group, result);
+	return ret;
 }
 
 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
@@ -1553,7 +1592,7 @@ int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
 	int sig = q->info.si_signo;
 	struct sigpending *pending;
 	unsigned long flags;
-	int ret;
+	int ret, result;
 
 	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
 
@@ -1562,7 +1601,8 @@ int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
 		goto ret;
 
 	ret = 1; /* the signal is ignored */
-	if (!prepare_signal(sig, t, 0))
+	result = TRACE_SIGNAL_IGNORED;
+	if (!prepare_signal(sig, t, false))
 		goto out;
 
 	ret = 0;
@@ -1573,6 +1613,7 @@ int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
 		 */
 		BUG_ON(q->info.si_code != SI_TIMER);
 		q->info.si_overrun++;
+		result = TRACE_SIGNAL_ALREADY_PENDING;
 		goto out;
 	}
 	q->info.si_overrun = 0;
@@ -1582,7 +1623,9 @@ int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
 	list_add_tail(&q->list, &pending->list);
 	sigaddset(&pending->signal, sig);
 	complete_signal(sig, t, group);
+	result = TRACE_SIGNAL_DELIVERED;
 out:
+	trace_signal_generate(sig, &q->info, t, group, result);
 	unlock_task_sighand(t, &flags);
 ret:
 	return ret;
@@ -1610,6 +1653,15 @@ bool do_notify_parent(struct task_struct *tsk, int sig)
 	BUG_ON(!tsk->ptrace &&
 	       (tsk->group_leader != tsk || !thread_group_empty(tsk)));
 
+	if (sig != SIGCHLD) {
+		/*
+		 * This is only possible if parent == real_parent.
+		 * Check if it has changed security domain.
+		 */
+		if (tsk->parent_exec_id != tsk->parent->self_exec_id)
+			sig = SIGCHLD;
+	}
+
 	info.si_signo = sig;
 	info.si_errno = 0;
 	/*
@@ -1626,13 +1678,12 @@ bool do_notify_parent(struct task_struct *tsk, int sig)
 	 */
 	rcu_read_lock();
 	info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
-	info.si_uid = __task_cred(tsk)->uid;
+	info.si_uid = map_cred_ns(__task_cred(tsk),
+			task_cred_xxx(tsk->parent, user_ns));
 	rcu_read_unlock();
 
-	info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime,
-				tsk->signal->utime));
-	info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime,
-				tsk->signal->stime));
+	info.si_utime = cputime_to_clock_t(tsk->utime + tsk->signal->utime);
+	info.si_stime = cputime_to_clock_t(tsk->stime + tsk->signal->stime);
 
 	info.si_status = tsk->exit_code & 0x7f;
 	if (tsk->exit_code & 0x80)
@@ -1711,7 +1762,8 @@ static void do_notify_parent_cldstop(struct task_struct *tsk,
 	 */
 	rcu_read_lock();
 	info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
-	info.si_uid = __task_cred(tsk)->uid;
+	info.si_uid = map_cred_ns(__task_cred(tsk),
+			task_cred_xxx(parent, user_ns));
 	rcu_read_unlock();
 
 	info.si_utime = cputime_to_clock_t(tsk->utime);
@@ -2127,8 +2179,11 @@ static int ptrace_signal(int signr, siginfo_t *info,
 		info->si_signo = signr;
 		info->si_errno = 0;
 		info->si_code = SI_USER;
+		rcu_read_lock();
 		info->si_pid = task_pid_vnr(current->parent);
-		info->si_uid = task_uid(current->parent);
+		info->si_uid = map_cred_ns(__task_cred(current->parent),
+				current_user_ns());
+		rcu_read_unlock();
 	}
 
 	/* If the (new) signal is now blocked, requeue it.  */
@@ -2320,6 +2375,27 @@ relock:
 	return signr;
 }
 
+/**
+ * block_sigmask - add @ka's signal mask to current->blocked
+ * @ka: action for @signr
+ * @signr: signal that has been successfully delivered
+ *
+ * This function should be called when a signal has succesfully been
+ * delivered. It adds the mask of signals for @ka to current->blocked
+ * so that they are blocked during the execution of the signal
+ * handler. In addition, @signr will be blocked unless %SA_NODEFER is
+ * set in @ka->sa.sa_flags.
+ */
+void block_sigmask(struct k_sigaction *ka, int signr)
+{
+	sigset_t blocked;
+
+	sigorsets(&blocked, &current->blocked, &ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
+		sigaddset(&blocked, signr);
+	set_current_blocked(&blocked);
+}
+
 /*
  * It could be that complete_signal() picked us to notify about the
  * group-wide signal. Other threads should be notified now to take
@@ -2357,8 +2433,15 @@ void exit_signals(struct task_struct *tsk)
 	int group_stop = 0;
 	sigset_t unblocked;
 
+	/*
+	 * @tsk is about to have PF_EXITING set - lock out users which
+	 * expect stable threadgroup.
+	 */
+	threadgroup_change_begin(tsk);
+
 	if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
 		tsk->flags |= PF_EXITING;
+		threadgroup_change_end(tsk);
 		return;
 	}
 
@@ -2368,6 +2451,9 @@ void exit_signals(struct task_struct *tsk)
 	 * see wants_signal(), do_signal_stop().
 	 */
 	tsk->flags |= PF_EXITING;
+
+	threadgroup_change_end(tsk);
+
 	if (!signal_pending(tsk))
 		goto out;