[PATCH 2/2] pidfs: add selftests for new namespace ioctls

From: Christian Brauner
Date: Mon Jul 22 2024 - 09:14:46 EST

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Previous message: Christian Brauner: "[PATCH 1/2] pidfs: handle kernels without namespaces cleanly"
In reply to: Christian Brauner: "[PATCH 1/2] pidfs: handle kernels without namespaces cleanly"
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Add selftests to verify that deriving namespace file descriptors from
pidfd file descriptors works correctly.

Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
---
.../selftests/pidfd/pidfd_setns_test.c | 258 +++++++++++++++---
1 file changed, 227 insertions(+), 31 deletions(-)

diff --git a/tools/testing/selftests/pidfd/pidfd_setns_test.c b/tools/testing/selftests/pidfd/pidfd_setns_test.c
index 47746b0c6acd..7c2a4349170a 100644
--- a/tools/testing/selftests/pidfd/pidfd_setns_test.c
+++ b/tools/testing/selftests/pidfd/pidfd_setns_test.c
@@ -16,11 +16,56 @@
#include <unistd.h>
#include <sys/socket.h>
#include <sys/stat.h>
+#include <linux/ioctl.h>

#include "pidfd.h"
#include "../clone3/clone3_selftests.h"
#include "../kselftest_harness.h"

+#ifndef PIDFS_IOCTL_MAGIC
+#define PIDFS_IOCTL_MAGIC 0xFF
+#endif
+
+#ifndef PIDFD_GET_CGROUP_NAMESPACE
+#define PIDFD_GET_CGROUP_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 1)
+#endif
+
+#ifndef PIDFD_GET_IPC_NAMESPACE
+#define PIDFD_GET_IPC_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 2)
+#endif
+
+#ifndef PIDFD_GET_MNT_NAMESPACE
+#define PIDFD_GET_MNT_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 3)
+#endif
+
+#ifndef PIDFD_GET_NET_NAMESPACE
+#define PIDFD_GET_NET_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 4)
+#endif
+
+#ifndef PIDFD_GET_PID_NAMESPACE
+#define PIDFD_GET_PID_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 5)
+#endif
+
+#ifndef PIDFD_GET_PID_FOR_CHILDREN_NAMESPACE
+#define PIDFD_GET_PID_FOR_CHILDREN_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 6)
+#endif
+
+#ifndef PIDFD_GET_TIME_NAMESPACE
+#define PIDFD_GET_TIME_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 7)
+#endif
+
+#ifndef PIDFD_GET_TIME_FOR_CHILDREN_NAMESPACE
+#define PIDFD_GET_TIME_FOR_CHILDREN_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 8)
+#endif
+
+#ifndef PIDFD_GET_USER_NAMESPACE
+#define PIDFD_GET_USER_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 9)
+#endif
+
+#ifndef PIDFD_GET_UTS_NAMESPACE
+#define PIDFD_GET_UTS_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 10)
+#endif
+
enum {
PIDFD_NS_USER,
PIDFD_NS_MNT,
@@ -31,22 +76,25 @@ enum {
PIDFD_NS_CGROUP,
PIDFD_NS_PIDCLD,
PIDFD_NS_TIME,
+ PIDFD_NS_TIMECLD,
PIDFD_NS_MAX
};

const struct ns_info {
const char *name;
int flag;
+ unsigned int pidfd_ioctl;
} ns_info[] = {
- [PIDFD_NS_USER] = { "user", CLONE_NEWUSER, },
- [PIDFD_NS_MNT] = { "mnt", CLONE_NEWNS, },
- [PIDFD_NS_PID] = { "pid", CLONE_NEWPID, },
- [PIDFD_NS_UTS] = { "uts", CLONE_NEWUTS, },
- [PIDFD_NS_IPC] = { "ipc", CLONE_NEWIPC, },
- [PIDFD_NS_NET] = { "net", CLONE_NEWNET, },
- [PIDFD_NS_CGROUP] = { "cgroup", CLONE_NEWCGROUP, },
- [PIDFD_NS_PIDCLD] = { "pid_for_children", 0, },
- [PIDFD_NS_TIME] = { "time", CLONE_NEWTIME, },
+ [PIDFD_NS_USER] = { "user", CLONE_NEWUSER, PIDFD_GET_USER_NAMESPACE, },
+ [PIDFD_NS_MNT] = { "mnt", CLONE_NEWNS, PIDFD_GET_MNT_NAMESPACE, },
+ [PIDFD_NS_PID] = { "pid", CLONE_NEWPID, PIDFD_GET_PID_NAMESPACE, },
+ [PIDFD_NS_UTS] = { "uts", CLONE_NEWUTS, PIDFD_GET_UTS_NAMESPACE, },
+ [PIDFD_NS_IPC] = { "ipc", CLONE_NEWIPC, PIDFD_GET_IPC_NAMESPACE, },
+ [PIDFD_NS_NET] = { "net", CLONE_NEWNET, PIDFD_GET_NET_NAMESPACE, },
+ [PIDFD_NS_CGROUP] = { "cgroup", CLONE_NEWCGROUP, PIDFD_GET_CGROUP_NAMESPACE, },
+ [PIDFD_NS_TIME] = { "time", CLONE_NEWTIME, PIDFD_GET_TIME_NAMESPACE, },
+ [PIDFD_NS_PIDCLD] = { "pid_for_children", 0, PIDFD_GET_PID_FOR_CHILDREN_NAMESPACE, },
+ [PIDFD_NS_TIMECLD] = { "time_for_children", 0, PIDFD_GET_TIME_FOR_CHILDREN_NAMESPACE, },
};

FIXTURE(current_nsset)
@@ -54,6 +102,7 @@ FIXTURE(current_nsset)
pid_t pid;
int pidfd;
int nsfds[PIDFD_NS_MAX];
+ int child_pidfd_derived_nsfds[PIDFD_NS_MAX];

pid_t child_pid_exited;
int child_pidfd_exited;
@@ -61,10 +110,12 @@ FIXTURE(current_nsset)
pid_t child_pid1;
int child_pidfd1;
int child_nsfds1[PIDFD_NS_MAX];
+ int child_pidfd_derived_nsfds1[PIDFD_NS_MAX];

pid_t child_pid2;
int child_pidfd2;
int child_nsfds2[PIDFD_NS_MAX];
+ int child_pidfd_derived_nsfds2[PIDFD_NS_MAX];
};

static int sys_waitid(int which, pid_t pid, int options)
@@ -128,9 +179,12 @@ FIXTURE_SETUP(current_nsset)
char c;

for (i = 0; i < PIDFD_NS_MAX; i++) {
- self->nsfds[i] = -EBADF;
- self->child_nsfds1[i] = -EBADF;
- self->child_nsfds2[i] = -EBADF;
+ self->nsfds[i] = -EBADF;
+ self->child_nsfds1[i] = -EBADF;
+ self->child_nsfds2[i] = -EBADF;
+ self->child_pidfd_derived_nsfds[i] = -EBADF;
+ self->child_pidfd_derived_nsfds1[i] = -EBADF;
+ self->child_pidfd_derived_nsfds2[i] = -EBADF;
}

proc_fd = open("/proc/self/ns", O_DIRECTORY | O_CLOEXEC);
@@ -139,6 +193,11 @@ FIXTURE_SETUP(current_nsset)
}

self->pid = getpid();
+ self->pidfd = sys_pidfd_open(self->pid, 0);
+ EXPECT_GT(self->pidfd, 0) {
+ TH_LOG("%m - Failed to open pidfd for process %d", self->pid);
+ }
+
for (i = 0; i < PIDFD_NS_MAX; i++) {
const struct ns_info *info = &ns_info[i];
self->nsfds[i] = openat(proc_fd, info->name, O_RDONLY | O_CLOEXEC);
@@ -148,20 +207,27 @@ FIXTURE_SETUP(current_nsset)
info->name, self->pid);
}
}
- }

- self->pidfd = sys_pidfd_open(self->pid, 0);
- EXPECT_GT(self->pidfd, 0) {
- TH_LOG("%m - Failed to open pidfd for process %d", self->pid);
+ self->child_pidfd_derived_nsfds[i] = ioctl(self->pidfd, info->pidfd_ioctl, 0);
+ if (self->child_pidfd_derived_nsfds[i] < 0) {
+ EXPECT_EQ(errno, EOPNOTSUPP) {
+ TH_LOG("%m - Failed to derive %s namespace from pidfd of process %d",
+ info->name, self->pid);
+ }
+ }
}

/* Create task that exits right away. */
- self->child_pid_exited = create_child(&self->child_pidfd_exited,
- CLONE_NEWUSER | CLONE_NEWNET);
+ self->child_pid_exited = create_child(&self->child_pidfd_exited, 0);
EXPECT_GE(self->child_pid_exited, 0);

- if (self->child_pid_exited == 0)
+ if (self->child_pid_exited == 0) {
+ if (self->nsfds[PIDFD_NS_USER] >= 0 && unshare(CLONE_NEWUSER) < 0)
+ _exit(EXIT_FAILURE);
+ if (self->nsfds[PIDFD_NS_NET] >= 0 && unshare(CLONE_NEWNET) < 0)
+ _exit(EXIT_FAILURE);
_exit(EXIT_SUCCESS);
+ }

ASSERT_EQ(sys_waitid(P_PID, self->child_pid_exited, WEXITED | WNOWAIT), 0);

@@ -174,18 +240,43 @@ FIXTURE_SETUP(current_nsset)
EXPECT_EQ(ret, 0);

/* Create tasks that will be stopped. */
- self->child_pid1 = create_child(&self->child_pidfd1,
- CLONE_NEWUSER | CLONE_NEWNS |
- CLONE_NEWCGROUP | CLONE_NEWIPC |
- CLONE_NEWUTS | CLONE_NEWPID |
- CLONE_NEWNET);
+ if (self->nsfds[PIDFD_NS_USER] >= 0 && self->nsfds[PIDFD_NS_PID] >= 0)
+ self->child_pid1 = create_child(&self->child_pidfd1, CLONE_NEWUSER | CLONE_NEWPID);
+ else if (self->nsfds[PIDFD_NS_PID] >= 0)
+ self->child_pid1 = create_child(&self->child_pidfd1, CLONE_NEWPID);
+ else if (self->nsfds[PIDFD_NS_USER] >= 0)
+ self->child_pid1 = create_child(&self->child_pidfd1, CLONE_NEWUSER);
+ else
+ self->child_pid1 = create_child(&self->child_pidfd1, 0);
EXPECT_GE(self->child_pid1, 0);

if (self->child_pid1 == 0) {
close(ipc_sockets[0]);

- if (!switch_timens())
+ if (self->nsfds[PIDFD_NS_MNT] >= 0 && unshare(CLONE_NEWNS) < 0) {
+ TH_LOG("%m - Failed to unshare mount namespace for process %d", self->pid);
_exit(EXIT_FAILURE);
+ }
+ if (self->nsfds[PIDFD_NS_CGROUP] >= 0 && unshare(CLONE_NEWCGROUP) < 0) {
+ TH_LOG("%m - Failed to unshare cgroup namespace for process %d", self->pid);
+ _exit(EXIT_FAILURE);
+ }
+ if (self->nsfds[PIDFD_NS_IPC] >= 0 && unshare(CLONE_NEWIPC) < 0) {
+ TH_LOG("%m - Failed to unshare ipc namespace for process %d", self->pid);
+ _exit(EXIT_FAILURE);
+ }
+ if (self->nsfds[PIDFD_NS_UTS] >= 0 && unshare(CLONE_NEWUTS) < 0) {
+ TH_LOG("%m - Failed to unshare uts namespace for process %d", self->pid);
+ _exit(EXIT_FAILURE);
+ }
+ if (self->nsfds[PIDFD_NS_NET] >= 0 && unshare(CLONE_NEWNET) < 0) {
+ TH_LOG("%m - Failed to unshare net namespace for process %d", self->pid);
+ _exit(EXIT_FAILURE);
+ }
+ if (self->nsfds[PIDFD_NS_TIME] >= 0 && !switch_timens()) {
+ TH_LOG("%m - Failed to unshare time namespace for process %d", self->pid);
+ _exit(EXIT_FAILURE);
+ }

if (write_nointr(ipc_sockets[1], "1", 1) < 0)
_exit(EXIT_FAILURE);
@@ -203,18 +294,43 @@ FIXTURE_SETUP(current_nsset)
ret = socketpair(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets);
EXPECT_EQ(ret, 0);

- self->child_pid2 = create_child(&self->child_pidfd2,
- CLONE_NEWUSER | CLONE_NEWNS |
- CLONE_NEWCGROUP | CLONE_NEWIPC |
- CLONE_NEWUTS | CLONE_NEWPID |
- CLONE_NEWNET);
+ if (self->nsfds[PIDFD_NS_USER] >= 0 && self->nsfds[PIDFD_NS_PID] >= 0)
+ self->child_pid2 = create_child(&self->child_pidfd2, CLONE_NEWUSER | CLONE_NEWPID);
+ else if (self->nsfds[PIDFD_NS_PID] >= 0)
+ self->child_pid2 = create_child(&self->child_pidfd2, CLONE_NEWPID);
+ else if (self->nsfds[PIDFD_NS_USER] >= 0)
+ self->child_pid2 = create_child(&self->child_pidfd2, CLONE_NEWUSER);
+ else
+ self->child_pid2 = create_child(&self->child_pidfd2, 0);
EXPECT_GE(self->child_pid2, 0);

if (self->child_pid2 == 0) {
close(ipc_sockets[0]);

- if (!switch_timens())
+ if (self->nsfds[PIDFD_NS_MNT] >= 0 && unshare(CLONE_NEWNS) < 0) {
+ TH_LOG("%m - Failed to unshare mount namespace for process %d", self->pid);
+ _exit(EXIT_FAILURE);
+ }
+ if (self->nsfds[PIDFD_NS_CGROUP] >= 0 && unshare(CLONE_NEWCGROUP) < 0) {
+ TH_LOG("%m - Failed to unshare cgroup namespace for process %d", self->pid);
_exit(EXIT_FAILURE);
+ }
+ if (self->nsfds[PIDFD_NS_IPC] >= 0 && unshare(CLONE_NEWIPC) < 0) {
+ TH_LOG("%m - Failed to unshare ipc namespace for process %d", self->pid);
+ _exit(EXIT_FAILURE);
+ }
+ if (self->nsfds[PIDFD_NS_UTS] >= 0 && unshare(CLONE_NEWUTS) < 0) {
+ TH_LOG("%m - Failed to unshare uts namespace for process %d", self->pid);
+ _exit(EXIT_FAILURE);
+ }
+ if (self->nsfds[PIDFD_NS_NET] >= 0 && unshare(CLONE_NEWNET) < 0) {
+ TH_LOG("%m - Failed to unshare net namespace for process %d", self->pid);
+ _exit(EXIT_FAILURE);
+ }
+ if (self->nsfds[PIDFD_NS_TIME] >= 0 && !switch_timens()) {
+ TH_LOG("%m - Failed to unshare time namespace for process %d", self->pid);
+ _exit(EXIT_FAILURE);
+ }

if (write_nointr(ipc_sockets[1], "1", 1) < 0)
_exit(EXIT_FAILURE);
@@ -267,6 +383,22 @@ FIXTURE_SETUP(current_nsset)
info->name, self->child_pid1);
}
}
+
+ self->child_pidfd_derived_nsfds1[i] = ioctl(self->child_pidfd1, info->pidfd_ioctl, 0);
+ if (self->child_pidfd_derived_nsfds1[i] < 0) {
+ EXPECT_EQ(errno, EOPNOTSUPP) {
+ TH_LOG("%m - Failed to derive %s namespace from pidfd of process %d",
+ info->name, self->child_pid1);
+ }
+ }
+
+ self->child_pidfd_derived_nsfds2[i] = ioctl(self->child_pidfd2, info->pidfd_ioctl, 0);
+ if (self->child_pidfd_derived_nsfds2[i] < 0) {
+ EXPECT_EQ(errno, EOPNOTSUPP) {
+ TH_LOG("%m - Failed to derive %s namespace from pidfd of process %d",
+ info->name, self->child_pid2);
+ }
+ }
}

close(proc_fd);
@@ -288,6 +420,12 @@ FIXTURE_TEARDOWN(current_nsset)
close(self->child_nsfds1[i]);
if (self->child_nsfds2[i] >= 0)
close(self->child_nsfds2[i]);
+ if (self->child_pidfd_derived_nsfds[i] >= 0)
+ close(self->child_pidfd_derived_nsfds[i]);
+ if (self->child_pidfd_derived_nsfds1[i] >= 0)
+ close(self->child_pidfd_derived_nsfds1[i]);
+ if (self->child_pidfd_derived_nsfds2[i] >= 0)
+ close(self->child_pidfd_derived_nsfds2[i]);
}

if (self->child_pidfd1 >= 0)
@@ -446,6 +584,42 @@ TEST_F(current_nsset, nsfd_incremental_setns)
}
}

+TEST_F(current_nsset, pidfd_derived_nsfd_incremental_setns)
+{
+ int i;
+ pid_t pid;
+
+ pid = getpid();
+ for (i = 0; i < PIDFD_NS_MAX; i++) {
+ const struct ns_info *info = &ns_info[i];
+ int nsfd;
+
+ if (self->child_pidfd_derived_nsfds1[i] < 0)
+ continue;
+
+ if (info->flag) {
+ ASSERT_EQ(setns(self->child_pidfd_derived_nsfds1[i], info->flag), 0) {
+ TH_LOG("%m - Failed to setns to %s namespace of %d via nsfd %d",
+ info->name, self->child_pid1,
+ self->child_pidfd_derived_nsfds1[i]);
+ }
+ }
+
+ /* Verify that we have changed to the correct namespaces. */
+ if (info->flag == CLONE_NEWPID)
+ nsfd = self->child_pidfd_derived_nsfds[i];
+ else
+ nsfd = self->child_pidfd_derived_nsfds1[i];
+ ASSERT_EQ(in_same_namespace(nsfd, pid, info->name), 1) {
+ TH_LOG("setns failed to place us correctly into %s namespace of %d via nsfd %d",
+ info->name, self->child_pid1,
+ self->child_pidfd_derived_nsfds1[i]);
+ }
+ TH_LOG("Managed to correctly setns to %s namespace of %d via nsfd %d",
+ info->name, self->child_pid1, self->child_pidfd_derived_nsfds1[i]);
+ }
+}
+
TEST_F(current_nsset, pidfd_one_shot_setns)
{
unsigned flags = 0;
@@ -542,6 +716,28 @@ TEST_F(current_nsset, no_foul_play)
info->name, self->child_pid2,
self->child_nsfds2[i]);
}
+
+ /*
+ * Can't setns to a user namespace outside of our hierarchy since we
+ * don't have caps in there and didn't create it. That means that under
+ * no circumstances should we be able to setns to any of the other
+ * ones since they aren't owned by our user namespace.
+ */
+ for (i = 0; i < PIDFD_NS_MAX; i++) {
+ const struct ns_info *info = &ns_info[i];
+
+ if (self->child_pidfd_derived_nsfds2[i] < 0 || !info->flag)
+ continue;
+
+ ASSERT_NE(setns(self->child_pidfd_derived_nsfds2[i], info->flag), 0) {
+ TH_LOG("Managed to setns to %s namespace of %d via nsfd %d",
+ info->name, self->child_pid2,
+ self->child_pidfd_derived_nsfds2[i]);
+ }
+ TH_LOG("%m - Correctly failed to setns to %s namespace of %d via nsfd %d",
+ info->name, self->child_pid2,
+ self->child_pidfd_derived_nsfds2[i]);
+ }
}

TEST(setns_einval)
--
2.43.0

Next message: Lorenzo Stoakes: "Re: [PATCH v5 10/21] mm/mmap: Support vma == NULL in init_vma_munmap()"
Previous message: Christian Brauner: "[PATCH 1/2] pidfs: handle kernels without namespaces cleanly"
In reply to: Christian Brauner: "[PATCH 1/2] pidfs: handle kernels without namespaces cleanly"
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