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selftests/namespaces: second active reference count tests

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Test namespace lifecycle: create a namespace in a child process, get a
file handle while it's active, then try to reopen after the process
exits (namespace becomes inactive).

Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-24-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2025-10-29 13:20:37 +01:00
parent 6bdce845fd
commit 721c7e41b1
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GPG Key ID: 91C61BC06578DCA2
1 changed files with 81 additions and 0 deletions
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81
tools/testing/selftests/namespaces/ns_active_ref_test.c
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@ -71,4 +71,85 @@ TEST(init_ns_always_active)
free(handle);
}
/*
* Test namespace lifecycle: create a namespace in a child process,
* get a file handle while it's active, then try to reopen after
* the process exits (namespace becomes inactive).
*/
TEST(ns_inactive_after_exit)
{
struct file_handle *handle;
int mount_id;
int ret;
int fd;
int pipefd[2];
pid_t pid;
int status;
char buf[sizeof(*handle) + MAX_HANDLE_SZ];
/* Create pipe for passing file handle from child */
ASSERT_EQ(pipe(pipefd), 0);
pid = fork();
ASSERT_GE(pid, 0);
if (pid == 0) {
/* Child process */
close(pipefd[0]);
/* Create new network namespace */
ret = unshare(CLONE_NEWNET);
if (ret < 0) {
close(pipefd[1]);
exit(1);
}
/* Open our new namespace */
fd = open("/proc/self/ns/net", O_RDONLY);
if (fd < 0) {
close(pipefd[1]);
exit(1);
}
/* Get file handle for the namespace */
handle = (struct file_handle *)buf;
handle->handle_bytes = MAX_HANDLE_SZ;
ret = name_to_handle_at(fd, "", handle, &mount_id, AT_EMPTY_PATH);
close(fd);
if (ret < 0) {
close(pipefd[1]);
exit(1);
}
/* Send handle to parent */
write(pipefd[1], buf, sizeof(*handle) + handle->handle_bytes);
close(pipefd[1]);
/* Exit - namespace should become inactive */
exit(0);
}
/* Parent process */
close(pipefd[1]);
/* Read file handle from child */
ret = read(pipefd[0], buf, sizeof(buf));
close(pipefd[0]);
/* Wait for child to exit */
waitpid(pid, &status, 0);
ASSERT_TRUE(WIFEXITED(status));
ASSERT_EQ(WEXITSTATUS(status), 0);
ASSERT_GT(ret, 0);
handle = (struct file_handle *)buf;
/* Try to reopen namespace - should fail with ENOENT since it's inactive */
fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);
ASSERT_LT(fd, 0);
/* Should fail with ENOENT (namespace inactive) or ESTALE */
ASSERT_TRUE(errno == ENOENT || errno == ESTALE);
}
TEST_HARNESS_MAIN