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selftests/namespaces: tenth active reference count tests 

Test multiple children sharing same parent.
Parent should stay active as long as ANY child is active.

Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-32-2e6f823ebdc0@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 13:20:45 +01:00
parent a8ce47a1ac
commit e7585a9ef5
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1 changed files with 170 additions and 0 deletions
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170
tools/testing/selftests/namespaces/ns_active_ref_test.c
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@ -1106,4 +1106,174 @@ TEST(ns_multilevel_hierarchy)
close(gp_fd);
}
/*
* Test multiple children sharing same parent.
* Parent should stay active as long as ANY child is active.
*/
TEST(ns_multiple_children_same_parent)
{
struct file_handle *p_handle, *c1_handle, *c2_handle;
int ret, pipefd[2];
pid_t pid;
int status;
__u64 p_id, c1_id, c2_id;
char p_buf[sizeof(*p_handle) + MAX_HANDLE_SZ];
char c1_buf[sizeof(*c1_handle) + MAX_HANDLE_SZ];
char c2_buf[sizeof(*c2_handle) + MAX_HANDLE_SZ];
ASSERT_EQ(pipe(pipefd), 0);
pid = fork();
ASSERT_GE(pid, 0);
if (pid == 0) {
close(pipefd[0]);
/* Create parent user namespace */
if (setup_userns() < 0) {
close(pipefd[1]);
exit(1);
}
int p_fd = open("/proc/self/ns/user", O_RDONLY);
if (p_fd < 0) {
close(pipefd[1]);
exit(1);
}
if (ioctl(p_fd, NS_GET_ID, &p_id) < 0) {
close(p_fd);
close(pipefd[1]);
exit(1);
}
close(p_fd);
/* Create first child user namespace */
if (setup_userns() < 0) {
close(pipefd[1]);
exit(1);
}
int c1_fd = open("/proc/self/ns/user", O_RDONLY);
if (c1_fd < 0) {
close(pipefd[1]);
exit(1);
}
if (ioctl(c1_fd, NS_GET_ID, &c1_id) < 0) {
close(c1_fd);
close(pipefd[1]);
exit(1);
}
close(c1_fd);
/* Return to parent user namespace and create second child */
/* We can't actually do this easily, so let's create a sibling namespace
* by creating a network namespace instead */
if (unshare(CLONE_NEWNET) < 0) {
close(pipefd[1]);
exit(1);
}
int c2_fd = open("/proc/self/ns/net", O_RDONLY);
if (c2_fd < 0) {
close(pipefd[1]);
exit(1);
}
if (ioctl(c2_fd, NS_GET_ID, &c2_id) < 0) {
close(c2_fd);
close(pipefd[1]);
exit(1);
}
close(c2_fd);
/* Send all namespace IDs */
write(pipefd[1], &p_id, sizeof(p_id));
write(pipefd[1], &c1_id, sizeof(c1_id));
write(pipefd[1], &c2_id, sizeof(c2_id));
close(pipefd[1]);
exit(0);
}
close(pipefd[1]);
/* Read all three namespace IDs - fixed size, no parsing needed */
ret = read(pipefd[0], &p_id, sizeof(p_id));
if (ret != sizeof(p_id)) {
close(pipefd[0]);
waitpid(pid, NULL, 0);
SKIP(return, "Failed to read parent namespace ID");
}
ret = read(pipefd[0], &c1_id, sizeof(c1_id));
if (ret != sizeof(c1_id)) {
close(pipefd[0]);
waitpid(pid, NULL, 0);
SKIP(return, "Failed to read first child namespace ID");
}
ret = read(pipefd[0], &c2_id, sizeof(c2_id));
close(pipefd[0]);
if (ret != sizeof(c2_id)) {
waitpid(pid, NULL, 0);
SKIP(return, "Failed to read second child namespace ID");
}
/* Construct file handles from namespace IDs */
p_handle = (struct file_handle *)p_buf;
p_handle->handle_bytes = sizeof(struct nsfs_file_handle);
p_handle->handle_type = FILEID_NSFS;
struct nsfs_file_handle *p_fh = (struct nsfs_file_handle *)p_handle->f_handle;
p_fh->ns_id = p_id;
p_fh->ns_type = 0;
p_fh->ns_inum = 0;
c1_handle = (struct file_handle *)c1_buf;
c1_handle->handle_bytes = sizeof(struct nsfs_file_handle);
c1_handle->handle_type = FILEID_NSFS;
struct nsfs_file_handle *c1_fh = (struct nsfs_file_handle *)c1_handle->f_handle;
c1_fh->ns_id = c1_id;
c1_fh->ns_type = 0;
c1_fh->ns_inum = 0;
c2_handle = (struct file_handle *)c2_buf;
c2_handle->handle_bytes = sizeof(struct nsfs_file_handle);
c2_handle->handle_type = FILEID_NSFS;
struct nsfs_file_handle *c2_fh = (struct nsfs_file_handle *)c2_handle->f_handle;
c2_fh->ns_id = c2_id;
c2_fh->ns_type = 0;
c2_fh->ns_inum = 0;
/* Open both children before process exits */
int c1_fd = open_by_handle_at(FD_NSFS_ROOT, c1_handle, O_RDONLY);
int c2_fd = open_by_handle_at(FD_NSFS_ROOT, c2_handle, O_RDONLY);
if (c1_fd < 0 || c2_fd < 0) {
if (c1_fd >= 0) close(c1_fd);
if (c2_fd >= 0) close(c2_fd);
waitpid(pid, NULL, 0);
SKIP(return, "Failed to open child namespaces");
}
waitpid(pid, &status, 0);
ASSERT_TRUE(WIFEXITED(status));
ASSERT_EQ(WEXITSTATUS(status), 0);
/* Parent should be active (both children active) */
TH_LOG("Both children active - parent should be active");
int p_fd = open_by_handle_at(FD_NSFS_ROOT, p_handle, O_RDONLY);
ASSERT_GE(p_fd, 0);
close(p_fd);
/* Close first child - parent should STILL be active */
TH_LOG("Closing first child - parent should still be active");
close(c1_fd);
p_fd = open_by_handle_at(FD_NSFS_ROOT, p_handle, O_RDONLY);
ASSERT_GE(p_fd, 0);
close(p_fd);
/* Close second child - NOW parent should become inactive */
TH_LOG("Closing second child - parent should become inactive");
close(c2_fd);
p_fd = open_by_handle_at(FD_NSFS_ROOT, p_handle, O_RDONLY);
ASSERT_LT(p_fd, 0);
}
TEST_HARNESS_MAIN