[PATCH v2 4/4] selftests/seccomp: Add test for atomic addfd+send

Sargun Dhillon
2021-05-17T19:40:01Z

From: Rodrigo Campos <rodrigo@kinvolk.io>

This just adds a test to verify that when using the new introduced flag
to ADDFD, a valid fd is added and returned as the syscall result.

Signed-off-by: Rodrigo Campos <rodrigo@kinvolk.io>
Signed-off-by: Sargun Dhillon <sargun@sargun.me>
Acked-by: Tycho Andersen <tycho@tycho.pizza>
---
tools/testing/selftests/seccomp/seccomp_bpf.c | 38 +++++++++++++++++++
1 file changed, 38 insertions(+)

diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index 98c3b647f54d..e2ba7adc2694 100644
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -235,6 +235,10 @@ struct seccomp_notif_addfd {
};
#endif

+#ifndef SECCOMP_ADDFD_FLAG_SEND
+#define SECCOMP_ADDFD_FLAG_SEND (1UL << 1) /* Addfd and return it, atomically */
+#endif
+
struct seccomp_notif_addfd_small {
__u64 id;
char weird[4];
@@ -3976,8 +3980,14 @@ TEST(user_notification_addfd)
ASSERT_GE(pid, 0);

if (pid == 0) {
+ /* fds will be added and this value is expected */
if (syscall(__NR_getppid) != USER_NOTIF_MAGIC)
exit(1);
+
+ /* Atomic addfd+send is received here. Check it is a valid fd */
+ if (fcntl(syscall(__NR_getppid), F_GETFD) == -1)
+ exit(1);
+
exit(syscall(__NR_getppid) != USER_NOTIF_MAGIC);
}

@@ -4056,6 +4066,30 @@ TEST(user_notification_addfd)
ASSERT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req), 0);
ASSERT_EQ(addfd.id, req.id);

+ /* Verify we can do an atomic addfd and send */
+ addfd.newfd = 0;
+ addfd.flags = SECCOMP_ADDFD_FLAG_SEND;
+ fd = ioctl(listener, SECCOMP_IOCTL_NOTIF_ADDFD, &addfd);
+
+ /* Child has fds 0-6 and 42 used, we expect the lower fd available: 7 */
+ EXPECT_EQ(fd, 7);
+ EXPECT_EQ(filecmp(getpid(), pid, memfd, fd), 0);
+
+ /*
+ * This sets the ID of the ADD FD to the last request plus 1. The
+ * notification ID increments 1 per notification.
+ */
+ addfd.id = req.id + 1;
+
+ /* This spins until the underlying notification is generated */
+ while (ioctl(listener, SECCOMP_IOCTL_NOTIF_ADDFD, &addfd) != -1 &&
+ errno != -EINPROGRESS)
+ nanosleep(&delay, NULL);
+
+ memset(&req, 0, sizeof(req));
+ ASSERT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req), 0);
+ ASSERT_EQ(addfd.id, req.id);
+
resp.id = req.id;
resp.error = 0;
resp.val = USER_NOTIF_MAGIC;
@@ -4116,6 +4150,10 @@ TEST(user_notification_addfd_rlimit)
EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_ADDFD, &addfd), -1);
EXPECT_EQ(errno, EMFILE);

+ addfd.flags = SECCOMP_ADDFD_FLAG_SEND;
+ EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_ADDFD, &addfd), -1);
+ EXPECT_EQ(errno, EMFILE);
+
addfd.newfd = 100;
addfd.flags = SECCOMP_ADDFD_FLAG_SETFD;
EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_ADDFD, &addfd), -1);
--
2.25.1