1 files changed, 105 insertions, 42 deletions

diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index dc77548167ef..fd023ac24e10 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -19,6 +19,8 @@
 #include <linux/compat.h>
 #include <linux/coredump.h>
 #include <linux/kmemleak.h>
+#include <linux/nospec.h>
+#include <linux/prctl.h>
 #include <linux/sched.h>
 #include <linux/sched/task_stack.h>
 #include <linux/seccomp.h>
@@ -227,8 +229,11 @@ static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
 	return true;
 }
 
+void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { }
+
 static inline void seccomp_assign_mode(struct task_struct *task,
-				       unsigned long seccomp_mode)
+				       unsigned long seccomp_mode,
+				       unsigned long flags)
 {
 	assert_spin_locked(&task->sighand->siglock);
 
@@ -238,6 +243,9 @@ static inline void seccomp_assign_mode(struct task_struct *task,
 	 * filter) is set.
 	 */
 	smp_mb__before_atomic();
+	/* Assume default seccomp processes want spec flaw mitigation. */
+	if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
+		arch_seccomp_spec_mitigate(task);
 	set_tsk_thread_flag(task, TIF_SECCOMP);
 }
 
@@ -305,7 +313,7 @@ static inline pid_t seccomp_can_sync_threads(void)
  * without dropping the locks.
  *
  */
-static inline void seccomp_sync_threads(void)
+static inline void seccomp_sync_threads(unsigned long flags)
 {
 	struct task_struct *thread, *caller;
 
@@ -346,7 +354,8 @@ static inline void seccomp_sync_threads(void)
 		 * allow one thread to transition the other.
 		 */
 		if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
-			seccomp_assign_mode(thread, SECCOMP_MODE_FILTER);
+			seccomp_assign_mode(thread, SECCOMP_MODE_FILTER,
+					    flags);
 	}
 }
 
@@ -469,7 +478,7 @@ static long seccomp_attach_filter(unsigned int flags,
 
 	/* Now that the new filter is in place, synchronize to all threads. */
 	if (flags & SECCOMP_FILTER_FLAG_TSYNC)
-		seccomp_sync_threads();
+		seccomp_sync_threads(flags);
 
 	return 0;
 }
@@ -584,18 +593,15 @@ static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
 	}
 
 	/*
-	 * Force an audit message to be emitted when the action is RET_KILL_*,
-	 * RET_LOG, or the FILTER_FLAG_LOG bit was set and the action is
-	 * allowed to be logged by the admin.
+	 * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
+	 * FILTER_FLAG_LOG bit was set. The admin has the ability to silence
+	 * any action from being logged by removing the action name from the
+	 * seccomp_actions_logged sysctl.
 	 */
-	if (log)
-		return __audit_seccomp(syscall, signr, action);
+	if (!log)
+		return;
 
-	/*
-	 * Let the audit subsystem decide if the action should be audited based
-	 * on whether the current task itself is being audited.
-	 */
-	return audit_seccomp(syscall, signr, action);
+	audit_seccomp(syscall, signr, action);
 }
 
 /*
@@ -818,7 +824,7 @@ static long seccomp_set_mode_strict(void)
 #ifdef TIF_NOTSC
 	disable_TSC();
 #endif
-	seccomp_assign_mode(current, seccomp_mode);
+	seccomp_assign_mode(current, seccomp_mode, 0);
 	ret = 0;
 
 out:
@@ -876,7 +882,7 @@ static long seccomp_set_mode_filter(unsigned int flags,
 	/* Do not free the successfully attached filter. */
 	prepared = NULL;
 
-	seccomp_assign_mode(current, seccomp_mode);
+	seccomp_assign_mode(current, seccomp_mode, flags);
 out:
 	spin_unlock_irq(&current->sighand->siglock);
 	if (flags & SECCOMP_FILTER_FLAG_TSYNC)
@@ -1135,10 +1141,11 @@ static const struct seccomp_log_name seccomp_log_names[] = {
 };
 
 static bool seccomp_names_from_actions_logged(char *names, size_t size,
-					      u32 actions_logged)
+					      u32 actions_logged,
+					      const char *sep)
 {
 	const struct seccomp_log_name *cur;
-	bool append_space = false;
+	bool append_sep = false;
 
 	for (cur = seccomp_log_names; cur->name && size; cur++) {
 		ssize_t ret;
@@ -1146,15 +1153,15 @@ static bool seccomp_names_from_actions_logged(char *names, size_t size,
 		if (!(actions_logged & cur->log))
 			continue;
 
-		if (append_space) {
-			ret = strscpy(names, " ", size);
+		if (append_sep) {
+			ret = strscpy(names, sep, size);
 			if (ret < 0)
 				return false;
 
 			names += ret;
 			size -= ret;
 		} else
-			append_space = true;
+			append_sep = true;
 
 		ret = strscpy(names, cur->name, size);
 		if (ret < 0)
@@ -1199,46 +1206,102 @@ static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names)
 	return true;
 }
 
-static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write,
-					  void __user *buffer, size_t *lenp,
-					  loff_t *ppos)
+static int read_actions_logged(struct ctl_table *ro_table, void __user *buffer,
+			       size_t *lenp, loff_t *ppos)
+{
+	char names[sizeof(seccomp_actions_avail)];
+	struct ctl_table table;
+
+	memset(names, 0, sizeof(names));
+
+	if (!seccomp_names_from_actions_logged(names, sizeof(names),
+					       seccomp_actions_logged, " "))
+		return -EINVAL;
+
+	table = *ro_table;
+	table.data = names;
+	table.maxlen = sizeof(names);
+	return proc_dostring(&table, 0, buffer, lenp, ppos);
+}
+
+static int write_actions_logged(struct ctl_table *ro_table, void __user *buffer,
+				size_t *lenp, loff_t *ppos, u32 *actions_logged)
 {
 	char names[sizeof(seccomp_actions_avail)];
 	struct ctl_table table;
 	int ret;
 
-	if (write && !capable(CAP_SYS_ADMIN))
+	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 
 	memset(names, 0, sizeof(names));
 
-	if (!write) {
-		if (!seccomp_names_from_actions_logged(names, sizeof(names),
-						       seccomp_actions_logged))
-			return -EINVAL;
-	}
-
 	table = *ro_table;
 	table.data = names;
 	table.maxlen = sizeof(names);
-	ret = proc_dostring(&table, write, buffer, lenp, ppos);
+	ret = proc_dostring(&table, 1, buffer, lenp, ppos);
 	if (ret)
 		return ret;
 
-	if (write) {
-		u32 actions_logged;
+	if (!seccomp_actions_logged_from_names(actions_logged, table.data))
+		return -EINVAL;
 
-		if (!seccomp_actions_logged_from_names(&actions_logged,
-						       table.data))
-			return -EINVAL;
+	if (*actions_logged & SECCOMP_LOG_ALLOW)
+		return -EINVAL;
 
-		if (actions_logged & SECCOMP_LOG_ALLOW)
-			return -EINVAL;
+	seccomp_actions_logged = *actions_logged;
+	return 0;
+}
 
-		seccomp_actions_logged = actions_logged;
-	}
+static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged,
+				 int ret)
+{
+	char names[sizeof(seccomp_actions_avail)];
+	char old_names[sizeof(seccomp_actions_avail)];
+	const char *new = names;
+	const char *old = old_names;
 
-	return 0;
+	if (!audit_enabled)
+		return;
+
+	memset(names, 0, sizeof(names));
+	memset(old_names, 0, sizeof(old_names));
+
+	if (ret)
+		new = "?";
+	else if (!actions_logged)
+		new = "(none)";
+	else if (!seccomp_names_from_actions_logged(names, sizeof(names),
+						    actions_logged, ","))
+		new = "?";
+
+	if (!old_actions_logged)
+		old = "(none)";
+	else if (!seccomp_names_from_actions_logged(old_names,
+						    sizeof(old_names),
+						    old_actions_logged, ","))
+		old = "?";
+
+	return audit_seccomp_actions_logged(new, old, !ret);
+}
+
+static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write,
+					  void __user *buffer, size_t *lenp,
+					  loff_t *ppos)
+{
+	int ret;
+
+	if (write) {
+		u32 actions_logged = 0;
+		u32 old_actions_logged = seccomp_actions_logged;
+
+		ret = write_actions_logged(ro_table, buffer, lenp, ppos,
+					   &actions_logged);
+		audit_actions_logged(actions_logged, old_actions_logged, ret);
+	} else
+		ret = read_actions_logged(ro_table, buffer, lenp, ppos);
+
+	return ret;
 }
 
 static struct ctl_path seccomp_sysctl_path[] = {