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Message-Id: <20251024-work-namespace-nstree-listns-v3-59-b6241981b72b@kernel.org>
Date: Fri, 24 Oct 2025 12:53:28 +0200
From: Christian Brauner <brauner@...nel.org>
To: linux-fsdevel@...r.kernel.org, Josef Bacik <josef@...icpanda.com>,
Jeff Layton <jlayton@...nel.org>
Cc: Jann Horn <jannh@...gle.com>, Mike Yuan <me@...dnzj.com>,
Zbigniew Jędrzejewski-Szmek <zbyszek@...waw.pl>,
Lennart Poettering <mzxreary@...inter.de>,
Daan De Meyer <daan.j.demeyer@...il.com>, Aleksa Sarai <cyphar@...har.com>,
Amir Goldstein <amir73il@...il.com>, Tejun Heo <tj@...nel.org>,
Johannes Weiner <hannes@...xchg.org>, Thomas Gleixner <tglx@...utronix.de>,
Alexander Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.cz>,
linux-kernel@...r.kernel.org, cgroups@...r.kernel.org, bpf@...r.kernel.org,
Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
netdev@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
Christian Brauner <brauner@...nel.org>
Subject: [PATCH v3 59/70] 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.
Signed-off-by: Christian Brauner <brauner@...nel.org>
---
.../testing/selftests/namespaces/siocgskns_test.c | 141 +++++++++++++++++++++
1 file changed, 141 insertions(+)
diff --git a/tools/testing/selftests/namespaces/siocgskns_test.c b/tools/testing/selftests/namespaces/siocgskns_test.c
index 231830daf5dc..60028eeecde0 100644
--- 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
--
2.47.3
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