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selftests/namespaces: ninth active reference count tests 

Test multi-level hierarchy (3+ levels deep).
Grandparent → Parent → Child
When child is active, both parent AND grandparent should be active.

Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-31-2e6f823ebdc0@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 13:20:44 +01:00
parent 94f8711080
commit a8ce47a1ac
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1 changed files with 164 additions and 0 deletions
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tools/testing/selftests/namespaces/ns_active_ref_test.c
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@ -942,4 +942,168 @@ TEST(ns_bind_mount_keeps_in_tree)
unlink(tmpfile);
}
/*
* Test multi-level hierarchy (3+ levels deep).
* Grandparent → Parent → Child
* When child is active, both parent AND grandparent should be active.
*/
TEST(ns_multilevel_hierarchy)
{
struct file_handle *gp_handle, *p_handle, *c_handle;
int ret, pipefd[2];
pid_t pid;
int status;
__u64 gp_id, p_id, c_id;
char gp_buf[sizeof(*gp_handle) + MAX_HANDLE_SZ];
char p_buf[sizeof(*p_handle) + MAX_HANDLE_SZ];
char c_buf[sizeof(*c_handle) + MAX_HANDLE_SZ];
ASSERT_EQ(pipe(pipefd), 0);
pid = fork();
ASSERT_GE(pid, 0);
if (pid == 0) {
close(pipefd[0]);
/* Create grandparent user namespace */
if (setup_userns() < 0) {
close(pipefd[1]);
exit(1);
}
int gp_fd = open("/proc/self/ns/user", O_RDONLY);
if (gp_fd < 0) {
close(pipefd[1]);
exit(1);
}
if (ioctl(gp_fd, NS_GET_ID, &gp_id) < 0) {
close(gp_fd);
close(pipefd[1]);
exit(1);
}
close(gp_fd);
/* 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 child user namespace */
if (setup_userns() < 0) {
close(pipefd[1]);
exit(1);
}
int c_fd = open("/proc/self/ns/user", O_RDONLY);
if (c_fd < 0) {
close(pipefd[1]);
exit(1);
}
if (ioctl(c_fd, NS_GET_ID, &c_id) < 0) {
close(c_fd);
close(pipefd[1]);
exit(1);
}
close(c_fd);
/* Send all three namespace IDs */
write(pipefd[1], &gp_id, sizeof(gp_id));
write(pipefd[1], &p_id, sizeof(p_id));
write(pipefd[1], &c_id, sizeof(c_id));
close(pipefd[1]);
exit(0);
}
close(pipefd[1]);
/* Read all three namespace IDs - fixed size, no parsing needed */
ret = read(pipefd[0], &gp_id, sizeof(gp_id));
if (ret != sizeof(gp_id)) {
close(pipefd[0]);
waitpid(pid, NULL, 0);
SKIP(return, "Failed to read grandparent namespace ID from child");
}
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 from child");
}
ret = read(pipefd[0], &c_id, sizeof(c_id));
close(pipefd[0]);
if (ret != sizeof(c_id)) {
waitpid(pid, NULL, 0);
SKIP(return, "Failed to read child namespace ID from child");
}
/* Construct file handles from namespace IDs */
gp_handle = (struct file_handle *)gp_buf;
gp_handle->handle_bytes = sizeof(struct nsfs_file_handle);
gp_handle->handle_type = FILEID_NSFS;
struct nsfs_file_handle *gp_fh = (struct nsfs_file_handle *)gp_handle->f_handle;
gp_fh->ns_id = gp_id;
gp_fh->ns_type = 0;
gp_fh->ns_inum = 0;
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;
c_handle = (struct file_handle *)c_buf;
c_handle->handle_bytes = sizeof(struct nsfs_file_handle);
c_handle->handle_type = FILEID_NSFS;
struct nsfs_file_handle *c_fh = (struct nsfs_file_handle *)c_handle->f_handle;
c_fh->ns_id = c_id;
c_fh->ns_type = 0;
c_fh->ns_inum = 0;
/* Open child before process exits */
int c_fd = open_by_handle_at(FD_NSFS_ROOT, c_handle, O_RDONLY);
if (c_fd < 0) {
waitpid(pid, NULL, 0);
SKIP(return, "Failed to open child namespace");
}
waitpid(pid, &status, 0);
ASSERT_TRUE(WIFEXITED(status));
ASSERT_EQ(WEXITSTATUS(status), 0);
/*
* With 3-level hierarchy and child active:
* - Child is active (we hold fd)
* - Parent should be active (propagated from child)
* - Grandparent should be active (propagated from parent)
*/
TH_LOG("Testing parent active when child is active");
int p_fd = open_by_handle_at(FD_NSFS_ROOT, p_handle, O_RDONLY);
ASSERT_GE(p_fd, 0);
TH_LOG("Testing grandparent active when child is active");
int gp_fd = open_by_handle_at(FD_NSFS_ROOT, gp_handle, O_RDONLY);
ASSERT_GE(gp_fd, 0);
close(c_fd);
close(p_fd);
close(gp_fd);
}
TEST_HARNESS_MAIN