selftests/pidfd: add pidfd setns tests

This is basically a test-suite for setns() and as of now contains:
- test that we can't pass garbage flags
- test that we can't attach to the namespaces of  task that has already exited
- test that we can incrementally setns into all namespaces of a target task
  using a pidfd
- test that we can setns atomically into all namespaces of a target task
- test that we can't cross setns into a user namespace outside of our user
  namespace hierarchy
- test that we can't setns into namespaces owned by user namespaces over which
  we are not privileged

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20200505140432.181565-4-christian.brauner@ubuntu.com
This commit is contained in:
Christian Brauner 2020-05-05 16:04:32 +02:00
parent 303cc571d1
commit 2b40c5db73
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
4 changed files with 482 additions and 1 deletions

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@ -5,3 +5,4 @@ pidfd_test
pidfd_wait
pidfd_fdinfo_test
pidfd_getfd_test
pidfd_setns_test

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@ -1,7 +1,8 @@
# SPDX-License-Identifier: GPL-2.0-only
CFLAGS += -g -I../../../../usr/include/ -pthread
TEST_GEN_PROGS := pidfd_test pidfd_fdinfo_test pidfd_open_test pidfd_poll_test pidfd_wait pidfd_getfd_test
TEST_GEN_PROGS := pidfd_test pidfd_fdinfo_test pidfd_open_test \
pidfd_poll_test pidfd_wait pidfd_getfd_test pidfd_setns_test
include ../lib.mk

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@ -0,0 +1,6 @@
CONFIG_UTS_NS=y
CONFIG_IPC_NS=y
CONFIG_USER_NS=y
CONFIG_PID_NS=y
CONFIG_NET_NS=y
CONFIG_CGROUPS=y

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@ -0,0 +1,473 @@
// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <linux/types.h>
#include <sched.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syscall.h>
#include <sys/prctl.h>
#include <sys/wait.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <linux/kcmp.h>
#include "pidfd.h"
#include "../clone3/clone3_selftests.h"
#include "../kselftest.h"
#include "../kselftest_harness.h"
enum {
PIDFD_NS_USER,
PIDFD_NS_MNT,
PIDFD_NS_PID,
PIDFD_NS_UTS,
PIDFD_NS_IPC,
PIDFD_NS_NET,
PIDFD_NS_CGROUP,
PIDFD_NS_PIDCLD,
PIDFD_NS_MAX
};
const struct ns_info {
const char *name;
int flag;
} 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, },
};
FIXTURE(current_nsset)
{
pid_t pid;
int pidfd;
int nsfds[PIDFD_NS_MAX];
pid_t child_pid_exited;
int child_pidfd_exited;
pid_t child_pid1;
int child_pidfd1;
int child_nsfds1[PIDFD_NS_MAX];
pid_t child_pid2;
int child_pidfd2;
int child_nsfds2[PIDFD_NS_MAX];
};
static int sys_waitid(int which, pid_t pid, int options)
{
return syscall(__NR_waitid, which, pid, NULL, options, NULL);
}
pid_t create_child(int *pidfd, unsigned flags)
{
struct clone_args args = {
.flags = CLONE_PIDFD | flags,
.exit_signal = SIGCHLD,
.pidfd = ptr_to_u64(pidfd),
};
return sys_clone3(&args, sizeof(struct clone_args));
}
FIXTURE_SETUP(current_nsset)
{
int i, proc_fd, ret;
for (i = 0; i < PIDFD_NS_MAX; i++) {
self->nsfds[i] = -EBADF;
self->child_nsfds1[i] = -EBADF;
self->child_nsfds2[i] = -EBADF;
}
proc_fd = open("/proc/self/ns", O_DIRECTORY | O_CLOEXEC);
ASSERT_GE(proc_fd, 0) {
TH_LOG("%m - Failed to open /proc/self/ns");
}
self->pid = getpid();
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);
if (self->nsfds[i] < 0) {
EXPECT_EQ(errno, ENOENT) {
TH_LOG("%m - Failed to open %s namespace for process %d",
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);
}
/* Create task that exits right away. */
self->child_pid_exited = create_child(&self->child_pidfd_exited,
CLONE_NEWUSER | CLONE_NEWNET);
EXPECT_GT(self->child_pid_exited, 0);
if (self->child_pid_exited == 0)
_exit(EXIT_SUCCESS);
ASSERT_EQ(sys_waitid(P_PID, self->child_pid_exited, WEXITED | WNOWAIT), 0);
self->pidfd = sys_pidfd_open(self->pid, 0);
EXPECT_GE(self->pidfd, 0) {
TH_LOG("%m - Failed to open pidfd for process %d", self->pid);
}
/* 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);
EXPECT_GE(self->child_pid1, 0);
if (self->child_pid1 == 0) {
pause();
_exit(EXIT_SUCCESS);
}
self->child_pid2 = create_child(&self->child_pidfd2,
CLONE_NEWUSER | CLONE_NEWNS |
CLONE_NEWCGROUP | CLONE_NEWIPC |
CLONE_NEWUTS | CLONE_NEWPID |
CLONE_NEWNET);
EXPECT_GE(self->child_pid2, 0);
if (self->child_pid2 == 0) {
pause();
_exit(EXIT_SUCCESS);
}
for (i = 0; i < PIDFD_NS_MAX; i++) {
char p[100];
const struct ns_info *info = &ns_info[i];
self->nsfds[i] = openat(proc_fd, info->name, O_RDONLY | O_CLOEXEC);
if (self->nsfds[i] < 0) {
EXPECT_EQ(errno, ENOENT) {
TH_LOG("%m - Failed to open %s namespace for process %d",
info->name, self->pid);
}
}
ret = snprintf(p, sizeof(p), "/proc/%d/ns/%s",
self->child_pid1, info->name);
EXPECT_GT(ret, 0);
EXPECT_LT(ret, sizeof(p));
self->child_nsfds1[i] = open(p, O_RDONLY | O_CLOEXEC);
if (self->child_nsfds1[i] < 0) {
EXPECT_EQ(errno, ENOENT) {
TH_LOG("%m - Failed to open %s namespace for process %d",
info->name, self->child_pid1);
}
}
ret = snprintf(p, sizeof(p), "/proc/%d/ns/%s",
self->child_pid2, info->name);
EXPECT_GT(ret, 0);
EXPECT_LT(ret, sizeof(p));
self->child_nsfds2[i] = open(p, O_RDONLY | O_CLOEXEC);
if (self->child_nsfds2[i] < 0) {
EXPECT_EQ(errno, ENOENT) {
TH_LOG("%m - Failed to open %s namespace for process %d",
info->name, self->child_pid1);
}
}
}
close(proc_fd);
}
FIXTURE_TEARDOWN(current_nsset)
{
int i;
ASSERT_EQ(sys_pidfd_send_signal(self->child_pidfd1,
SIGKILL, NULL, 0), 0);
ASSERT_EQ(sys_pidfd_send_signal(self->child_pidfd2,
SIGKILL, NULL, 0), 0);
for (i = 0; i < PIDFD_NS_MAX; i++) {
if (self->nsfds[i] >= 0)
close(self->nsfds[i]);
if (self->child_nsfds1[i] >= 0)
close(self->child_nsfds1[i]);
if (self->child_nsfds2[i] >= 0)
close(self->child_nsfds2[i]);
}
if (self->child_pidfd1 >= 0)
EXPECT_EQ(0, close(self->child_pidfd1));
if (self->child_pidfd2 >= 0)
EXPECT_EQ(0, close(self->child_pidfd2));
ASSERT_EQ(sys_waitid(P_PID, self->child_pid_exited, WEXITED), 0);
ASSERT_EQ(sys_waitid(P_PID, self->child_pid1, WEXITED), 0);
ASSERT_EQ(sys_waitid(P_PID, self->child_pid2, WEXITED), 0);
}
static int preserve_ns(const int pid, const char *ns)
{
int ret;
char path[50];
ret = snprintf(path, sizeof(path), "/proc/%d/ns/%s", pid, ns);
if (ret < 0 || (size_t)ret >= sizeof(path))
return -EIO;
return open(path, O_RDONLY | O_CLOEXEC);
}
static int in_same_namespace(int ns_fd1, pid_t pid2, const char *ns)
{
int ns_fd2 = -EBADF;
int ret = -1;
struct stat ns_st1, ns_st2;
ret = fstat(ns_fd1, &ns_st1);
if (ret < 0)
return -1;
ns_fd2 = preserve_ns(pid2, ns);
if (ns_fd2 < 0)
return -1;
ret = fstat(ns_fd2, &ns_st2);
close(ns_fd2);
if (ret < 0)
return -1;
/* processes are in the same namespace */
if ((ns_st1.st_dev == ns_st2.st_dev) &&
(ns_st1.st_ino == ns_st2.st_ino))
return 1;
/* processes are in different namespaces */
return 0;
}
/* Test that we can't pass garbage to the kernel. */
TEST_F(current_nsset, invalid_flags)
{
ASSERT_NE(setns(self->pidfd, 0), 0);
EXPECT_EQ(errno, EINVAL);
ASSERT_NE(setns(self->pidfd, -1), 0);
EXPECT_EQ(errno, EINVAL);
ASSERT_NE(setns(self->pidfd, CLONE_VM), 0);
EXPECT_EQ(errno, EINVAL);
ASSERT_NE(setns(self->pidfd, CLONE_NEWUSER | CLONE_VM), 0);
EXPECT_EQ(errno, EINVAL);
}
/* Test that we can't attach to a task that has already exited. */
TEST_F(current_nsset, pidfd_exited_child)
{
int i;
pid_t pid;
ASSERT_NE(setns(self->child_pidfd_exited, CLONE_NEWUSER | CLONE_NEWNET),
0);
EXPECT_EQ(errno, ESRCH);
pid = getpid();
for (i = 0; i < PIDFD_NS_MAX; i++) {
const struct ns_info *info = &ns_info[i];
/* Verify that we haven't changed any namespaces. */
if (self->nsfds[i] >= 0)
ASSERT_EQ(in_same_namespace(self->nsfds[i], pid, info->name), 1);
}
}
TEST_F(current_nsset, pidfd_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_nsfds1[i] < 0)
continue;
if (info->flag) {
ASSERT_EQ(setns(self->child_pidfd1, info->flag), 0) {
TH_LOG("%m - Failed to setns to %s namespace of %d via pidfd %d",
info->name, self->child_pid1,
self->child_pidfd1);
}
}
/* Verify that we have changed to the correct namespaces. */
if (info->flag == CLONE_NEWPID)
nsfd = self->nsfds[i];
else
nsfd = self->child_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 pidfd %d",
info->name, self->child_pid1,
self->child_pidfd1);
}
TH_LOG("Managed to correctly setns to %s namespace of %d via pidfd %d",
info->name, self->child_pid1, self->child_pidfd1);
}
}
TEST_F(current_nsset, 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_nsfds1[i] < 0)
continue;
if (info->flag) {
ASSERT_EQ(setns(self->child_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_nsfds1[i]);
}
}
/* Verify that we have changed to the correct namespaces. */
if (info->flag == CLONE_NEWPID)
nsfd = self->nsfds[i];
else
nsfd = self->child_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_nsfds1[i]);
}
TH_LOG("Managed to correctly setns to %s namespace of %d via nsfd %d",
info->name, self->child_pid1, self->child_nsfds1[i]);
}
}
TEST_F(current_nsset, pidfd_one_shot_setns)
{
unsigned flags = 0;
int i;
pid_t pid;
for (i = 0; i < PIDFD_NS_MAX; i++) {
const struct ns_info *info = &ns_info[i];
if (self->child_nsfds1[i] < 0)
continue;
flags |= info->flag;
TH_LOG("Adding %s namespace of %d to list of namespaces to attach to",
info->name, self->child_pid1);
}
ASSERT_EQ(setns(self->child_pidfd1, flags), 0) {
TH_LOG("%m - Failed to setns to namespaces of %d",
self->child_pid1);
}
pid = getpid();
for (i = 0; i < PIDFD_NS_MAX; i++) {
const struct ns_info *info = &ns_info[i];
int nsfd;
if (self->child_nsfds1[i] < 0)
continue;
/* Verify that we have changed to the correct namespaces. */
if (info->flag == CLONE_NEWPID)
nsfd = self->nsfds[i];
else
nsfd = self->child_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",
info->name, self->child_pid1);
}
TH_LOG("Managed to correctly setns to %s namespace of %d",
info->name, self->child_pid1);
}
}
TEST_F(current_nsset, no_foul_play)
{
unsigned flags = 0;
int i;
for (i = 0; i < PIDFD_NS_MAX; i++) {
const struct ns_info *info = &ns_info[i];
if (self->child_nsfds1[i] < 0)
continue;
flags |= info->flag;
if (info->flag) /* No use logging pid_for_children. */
TH_LOG("Adding %s namespace of %d to list of namespaces to attach to",
info->name, self->child_pid1);
}
ASSERT_EQ(setns(self->child_pidfd1, flags), 0) {
TH_LOG("%m - Failed to setns to namespaces of %d vid pidfd %d",
self->child_pid1, self->child_pidfd1);
}
/*
* 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_nsfds2[i] < 0 || !info->flag)
continue;
ASSERT_NE(setns(self->child_pidfd2, info->flag), 0) {
TH_LOG("Managed to setns to %s namespace of %d via pidfd %d",
info->name, self->child_pid2,
self->child_pidfd2);
}
TH_LOG("%m - Correctly failed to setns to %s namespace of %d via pidfd %d",
info->name, self->child_pid2,
self->child_pidfd2);
ASSERT_NE(setns(self->child_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_nsfds2[i]);
}
TH_LOG("%m - Correctly failed to setns to %s namespace of %d via nsfd %d",
info->name, self->child_pid2,
self->child_nsfds2[i]);
}
}
TEST_HARNESS_MAIN