selftests/seccomp: Catch garbage on SECCOMP_IOCTL_NOTIF_RECV

This adds logic to the user_notification_basic test to set a member
of struct seccomp_notif to an invalid value to ensure that the kernel
returns EINVAL if any of the struct seccomp_notif members are set to
invalid values.

Signed-off-by: Sargun Dhillon <sargun@sargun.me>
Suggested-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20191230203811.4996-1-sargun@sargun.me
Fixes: 6a21cc50f0c7 ("seccomp: add a return code to trap to userspace")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>

diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index f53f14971bff9fa13fc761a379ebcf199f38c055..ee1b727ede045dfd920bf319d3729efd217ef137 100644 (file)
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -3158,7 +3158,18 @@ TEST(user_notification_basic)
        EXPECT_GT(poll(&pollfd, 1, -1), 0);
        EXPECT_EQ(pollfd.revents, POLLIN);
 
-       EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req), 0);
+       /* Test that we can't pass garbage to the kernel. */
+       memset(&req, 0, sizeof(req));
+       req.pid = -1;
+       errno = 0;
+       ret = ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req);
+       EXPECT_EQ(-1, ret);
+       EXPECT_EQ(EINVAL, errno);
+
+       if (ret) {
+               req.pid = 0;
+               EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req), 0);
+       }
 
        pollfd.fd = listener;
        pollfd.events = POLLIN | POLLOUT;