selftests/namespaces: seventh inactive namespace resurrection test

Test socket keeps netns active after creating process exits. Verify that
as long as the socket FD exists, the namespace remains active.

Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-61-2e6f823ebdc0@kernel.org
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/tools/testing/selftests/namespaces/siocgskns_test.c b/tools/testing/selftests/namespaces/siocgskns_test.c
index 231830daf5dc7420564afb31fde4bea9f2cca7d6..60028eeecde07836a08f223d063b2cc4aae28b7b 100644 (file)
--- a/tools/testing/selftests/namespaces/siocgskns_test.c
+++ b/tools/testing/selftests/namespaces/siocgskns_test.c
@@ -401,4 +401,145 @@ TEST(siocgskns_multiple_sockets)
        }
 }
 
+/*
+ * Test socket keeps netns active after creating process exits.
+ * Verify that as long as the socket FD exists, the namespace remains active.
+ */
+TEST(siocgskns_netns_lifecycle)
+{
+       int sock_fd, netns_fd;
+       int ipc_sockets[2];
+       int syncpipe[2];
+       pid_t pid;
+       int status;
+       char sync_byte;
+       struct stat st;
+       ino_t netns_ino;
+
+       EXPECT_EQ(socketpair(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets), 0);
+
+       ASSERT_EQ(pipe(syncpipe), 0);
+
+       pid = fork();
+       ASSERT_GE(pid, 0);
+
+       if (pid == 0) {
+               /* Child */
+               close(ipc_sockets[0]);
+               close(syncpipe[1]);
+
+               if (unshare(CLONE_NEWNET) < 0) {
+                       close(ipc_sockets[1]);
+                       close(syncpipe[0]);
+                       exit(1);
+               }
+
+               sock_fd = socket(AF_INET, SOCK_STREAM, 0);
+               if (sock_fd < 0) {
+                       close(ipc_sockets[1]);
+                       close(syncpipe[0]);
+                       exit(1);
+               }
+
+               /* Send socket to parent */
+               struct msghdr msg = {0};
+               struct iovec iov = {0};
+               char buf[1] = {'X'};
+               char cmsg_buf[CMSG_SPACE(sizeof(int))];
+
+               iov.iov_base = buf;
+               iov.iov_len = 1;
+               msg.msg_iov = &iov;
+               msg.msg_iovlen = 1;
+               msg.msg_control = cmsg_buf;
+               msg.msg_controllen = sizeof(cmsg_buf);
+
+               struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
+               cmsg->cmsg_level = SOL_SOCKET;
+               cmsg->cmsg_type = SCM_RIGHTS;
+               cmsg->cmsg_len = CMSG_LEN(sizeof(int));
+               memcpy(CMSG_DATA(cmsg), &sock_fd, sizeof(int));
+
+               if (sendmsg(ipc_sockets[1], &msg, 0) < 0) {
+                       close(sock_fd);
+                       close(ipc_sockets[1]);
+                       close(syncpipe[0]);
+                       exit(1);
+               }
+
+               close(sock_fd);
+               close(ipc_sockets[1]);
+
+               /* Wait for parent signal */
+               read(syncpipe[0], &sync_byte, 1);
+               close(syncpipe[0]);
+               exit(0);
+       }
+
+       /* Parent */
+       close(ipc_sockets[1]);
+       close(syncpipe[0]);
+
+       /* Receive socket FD */
+       struct msghdr msg = {0};
+       struct iovec iov = {0};
+       char buf[1];
+       char cmsg_buf[CMSG_SPACE(sizeof(int))];
+
+       iov.iov_base = buf;
+       iov.iov_len = 1;
+       msg.msg_iov = &iov;
+       msg.msg_iovlen = 1;
+       msg.msg_control = cmsg_buf;
+       msg.msg_controllen = sizeof(cmsg_buf);
+
+       ssize_t n = recvmsg(ipc_sockets[0], &msg, 0);
+       close(ipc_sockets[0]);
+       ASSERT_EQ(n, 1);
+
+       struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
+       ASSERT_NE(cmsg, NULL);
+       memcpy(&sock_fd, CMSG_DATA(cmsg), sizeof(int));
+
+       /* Get netns from socket while child is alive */
+       netns_fd = ioctl(sock_fd, SIOCGSKNS);
+       if (netns_fd < 0) {
+               sync_byte = 'G';
+               write(syncpipe[1], &sync_byte, 1);
+               close(syncpipe[1]);
+               close(sock_fd);
+               waitpid(pid, NULL, 0);
+               if (errno == ENOTTY || errno == EINVAL)
+                       SKIP(return, "SIOCGSKNS not supported");
+               ASSERT_GE(netns_fd, 0);
+       }
+       ASSERT_EQ(fstat(netns_fd, &st), 0);
+       netns_ino = st.st_ino;
+
+       /* Signal child to exit */
+       sync_byte = 'G';
+       write(syncpipe[1], &sync_byte, 1);
+       close(syncpipe[1]);
+
+       waitpid(pid, &status, 0);
+       ASSERT_TRUE(WIFEXITED(status));
+
+       /*
+        * Socket FD should still keep namespace active even after
+        * the creating process exited.
+        */
+       int test_fd = ioctl(sock_fd, SIOCGSKNS);
+       ASSERT_GE(test_fd, 0);
+
+       struct stat st_test;
+       ASSERT_EQ(fstat(test_fd, &st_test), 0);
+       ASSERT_EQ(st_test.st_ino, netns_ino);
+
+       close(test_fd);
+       close(netns_fd);
+
+       /* Close socket - namespace should become inactive */
+       close(sock_fd);
+}
+
 TEST_HARNESS_MAIN