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Message-Id: <20200527111902.163213-2-christian.brauner@ubuntu.com>
Date: Wed, 27 May 2020 13:19:02 +0200
From: Christian Brauner <christian.brauner@...ntu.com>
To: linux-kernel@...r.kernel.org, Kees Cook <keescook@...omium.org>
Cc: Andy Lutomirski <luto@...nel.org>, Tycho Andersen <tycho@...ho.ws>,
Matt Denton <mpdenton@...gle.com>,
Sargun Dhillon <sargun@...gun.me>,
Jann Horn <jannh@...gle.com>, Chris Palmer <palmer@...gle.com>,
Aleksa Sarai <cyphar@...har.com>,
Robert Sesek <rsesek@...gle.com>,
Jeffrey Vander Stoep <jeffv@...gle.com>,
Linux Containers <containers@...ts.linux-foundation.org>,
Christian Brauner <christian.brauner@...ntu.com>
Subject: [PATCH 2/2] tests: test seccomp filter notifications
This verifies we're correctly notified when a seccomp filter becomes
unused when a notifier is in use.
Signed-off-by: Christian Brauner <christian.brauner@...ntu.com>
---
tools/testing/selftests/seccomp/seccomp_bpf.c | 137 ++++++++++++++++++
1 file changed, 137 insertions(+)
diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index c0aa46ce14f6..472b93b1c3d5 100644
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -45,12 +45,14 @@
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <linux/kcmp.h>
+#include <sys/epoll.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <poll.h>
#include "../kselftest_harness.h"
+#include "../clone3/clone3_selftests.h"
#ifndef PR_SET_PTRACER
# define PR_SET_PTRACER 0x59616d61
@@ -3686,6 +3688,141 @@ TEST(user_notification_continue)
}
}
+TEST(user_notification_filter_empty)
+{
+ pid_t pid;
+ long ret;
+ int status;
+ struct pollfd pollfd;
+ struct clone_args args = {
+ .flags = CLONE_FILES,
+ .exit_signal = SIGCHLD,
+ };
+
+ ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
+ ASSERT_EQ(0, ret) {
+ TH_LOG("Kernel does not support PR_SET_NO_NEW_PRIVS!");
+ }
+
+ pid = sys_clone3(&args, sizeof(args));
+ ASSERT_GE(pid, 0);
+
+ if (pid == 0) {
+ int listener;
+
+ listener = user_trap_syscall(__NR_mknod, SECCOMP_FILTER_FLAG_NEW_LISTENER);
+ if (listener < 0)
+ _exit(EXIT_FAILURE);
+
+ if (dup2(listener, 200) != 200)
+ _exit(EXIT_FAILURE);
+
+ close(listener);
+
+ _exit(EXIT_SUCCESS);
+ }
+
+ EXPECT_EQ(waitpid(pid, &status, 0), pid);
+ EXPECT_EQ(true, WIFEXITED(status));
+ EXPECT_EQ(0, WEXITSTATUS(status));
+
+ /*
+ * The seccomp filter has become unused so we should be notified once
+ * the kernel gets around to cleaning up task struct.
+ */
+ pollfd.fd = 200;
+ pollfd.events = POLLHUP;
+
+ EXPECT_GT(poll(&pollfd, 1, -1), 0);
+ EXPECT_GT((pollfd.revents & POLLHUP) ?: 0, 0);
+}
+
+static void *do_thread(void *data)
+{
+ return NULL;
+}
+
+TEST(user_notification_filter_empty_threaded)
+{
+ pid_t pid;
+ long ret;
+ int status;
+ struct pollfd pollfd;
+ struct clone_args args = {
+ .flags = CLONE_FILES,
+ .exit_signal = SIGCHLD,
+ };
+
+ ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
+ ASSERT_EQ(0, ret) {
+ TH_LOG("Kernel does not support PR_SET_NO_NEW_PRIVS!");
+ }
+
+ pid = sys_clone3(&args, sizeof(args));
+ ASSERT_GE(pid, 0);
+
+ if (pid == 0) {
+ pid_t pid1, pid2;
+ int listener, status;
+ pthread_t thread;
+
+ listener = user_trap_syscall(__NR_dup, SECCOMP_FILTER_FLAG_NEW_LISTENER);
+ if (listener < 0)
+ _exit(EXIT_FAILURE);
+
+ if (dup2(listener, 200) != 200)
+ _exit(EXIT_FAILURE);
+
+ close(listener);
+
+ pid1 = fork();
+ if (pid1 < 0)
+ _exit(EXIT_FAILURE);
+
+ if (pid1 == 0)
+ _exit(EXIT_SUCCESS);
+
+ pid2 = fork();
+ if (pid2 < 0)
+ _exit(EXIT_FAILURE);
+
+ if (pid2 == 0)
+ _exit(EXIT_SUCCESS);
+
+ if (pthread_create(&thread, NULL, do_thread, NULL) ||
+ pthread_join(thread, NULL))
+ _exit(EXIT_FAILURE);
+
+ if (pthread_create(&thread, NULL, do_thread, NULL) ||
+ pthread_join(thread, NULL))
+ _exit(EXIT_FAILURE);
+
+ if (waitpid(pid1, &status, 0) != pid1 || !WIFEXITED(status) ||
+ WEXITSTATUS(status))
+ _exit(EXIT_FAILURE);
+
+ if (waitpid(pid2, &status, 0) != pid2 || !WIFEXITED(status) ||
+ WEXITSTATUS(status))
+ _exit(EXIT_FAILURE);
+
+ exit(EXIT_SUCCESS);
+ }
+
+ EXPECT_EQ(waitpid(pid, &status, 0), pid);
+ EXPECT_EQ(true, WIFEXITED(status));
+ EXPECT_EQ(0, WEXITSTATUS(status));
+
+ /*
+ * The seccomp filter has become unused so we should be notified once
+ * the kernel gets around to cleaning up task struct.
+ */
+ pollfd.fd = 200;
+ pollfd.events = POLLHUP;
+
+ EXPECT_GT(poll(&pollfd, 1, -1), 0);
+ EXPECT_GT((pollfd.revents & POLLHUP) ?: 0, 0);
+}
+
/*
* TODO:
* - add microbenchmarks
--
2.26.2
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