Signed-off-by: Aleksa Sarai cyphar@cyphar.com --- tools/testing/selftests/proc/.gitignore | 1 + tools/testing/selftests/proc/Makefile | 1 + tools/testing/selftests/proc/proc-pidns.c | 252 ++++++++++++++++++++++++++++++ 3 files changed, 254 insertions(+)
diff --git a/tools/testing/selftests/proc/.gitignore b/tools/testing/selftests/proc/.gitignore index 973968f45bba..2dced03e9e0e 100644 --- a/tools/testing/selftests/proc/.gitignore +++ b/tools/testing/selftests/proc/.gitignore @@ -17,6 +17,7 @@ /proc-tid0 /proc-uptime-001 /proc-uptime-002 +/proc-pidns /read /self /setns-dcache diff --git a/tools/testing/selftests/proc/Makefile b/tools/testing/selftests/proc/Makefile index b12921b9794b..c6f7046b9860 100644 --- a/tools/testing/selftests/proc/Makefile +++ b/tools/testing/selftests/proc/Makefile @@ -27,5 +27,6 @@ TEST_GEN_PROGS += setns-sysvipc TEST_GEN_PROGS += thread-self TEST_GEN_PROGS += proc-multiple-procfs TEST_GEN_PROGS += proc-fsconfig-hidepid +TEST_GEN_PROGS += proc-pidns
include ../lib.mk diff --git a/tools/testing/selftests/proc/proc-pidns.c b/tools/testing/selftests/proc/proc-pidns.c new file mode 100644 index 000000000000..5994375e2377 --- /dev/null +++ b/tools/testing/selftests/proc/proc-pidns.c @@ -0,0 +1,252 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Author: Aleksa Sarai cyphar@cyphar.com + * Copyright (C) 2025 SUSE LLC. + */ + +#include <assert.h> +#include <errno.h> +#include <sched.h> +#include <stdbool.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <stdio.h> +#include <sys/mount.h> +#include <sys/stat.h> +#include <sys/ioctl.h> +#include <sys/prctl.h> + +#include "../kselftest_harness.h" + +#define ASSERT_ERRNO(expected, _t, seen) \ + __EXPECT(expected, #expected, \ + ({__typeof__(seen) _tmp_seen = (seen); \ + _tmp_seen >= 0 ? _tmp_seen : -errno; }), #seen, _t, 1) + +#define ASSERT_ERRNO_EQ(expected, seen) \ + ASSERT_ERRNO(expected, ==, seen) + +#define ASSERT_SUCCESS(seen) \ + ASSERT_ERRNO(0, <=, seen) + +static int touch(char *path) +{ + int fd = open(path, O_WRONLY|O_CREAT|O_CLOEXEC, 0644); + if (fd < 0) + return -1; + return close(fd); +} + +FIXTURE(ns) +{ + int host_mntns, host_pidns; + int dummy_pidns; +}; + +FIXTURE_SETUP(ns) +{ + /* Stash the old mntns. */ + self->host_mntns = open("/proc/self/ns/mnt", O_RDONLY|O_CLOEXEC); + ASSERT_SUCCESS(self->host_mntns); + + /* Create a new mount namespace and make it private. */ + ASSERT_SUCCESS(unshare(CLONE_NEWNS)); + ASSERT_SUCCESS(mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL)); + + /* + * Create a proper tmpfs that we can use and will disappear once we + * leave this mntns. + */ + ASSERT_SUCCESS(mount("tmpfs", "/tmp", "tmpfs", 0, NULL)); + + /* + * Create a pidns we can use for later tests. We need to fork off a + * child so that we get a usable nsfd that we can bind-mount and open. + */ + ASSERT_SUCCESS(touch("/tmp/dummy-pidns")); + + self->host_pidns = open("/proc/self/ns/pid", O_RDONLY|O_CLOEXEC); + ASSERT_SUCCESS(self->host_pidns); + ASSERT_SUCCESS(unshare(CLONE_NEWPID)); + + pid_t pid = fork(); + ASSERT_SUCCESS(pid); + if (!pid) { + prctl(PR_SET_PDEATHSIG, SIGKILL); + ASSERT_SUCCESS(mount("/proc/self/ns/pid", "/tmp/dummy-pidns", NULL, MS_BIND, 0)); + exit(0); + } + + int wstatus; + ASSERT_EQ(waitpid(pid, &wstatus, 0), pid); + ASSERT_TRUE(WIFEXITED(wstatus)); + ASSERT_EQ(WEXITSTATUS(wstatus), 0); + + ASSERT_SUCCESS(setns(self->host_pidns, CLONE_NEWPID)); + + self->dummy_pidns = open("/tmp/dummy-pidns", O_RDONLY|O_CLOEXEC); + ASSERT_SUCCESS(self->dummy_pidns); +} + +FIXTURE_TEARDOWN(ns) +{ + ASSERT_SUCCESS(setns(self->host_mntns, CLONE_NEWNS)); + ASSERT_SUCCESS(close(self->host_mntns)); + + ASSERT_SUCCESS(close(self->host_pidns)); + ASSERT_SUCCESS(close(self->dummy_pidns)); +} + +TEST_F(ns, pidns_mount_string_path) +{ + ASSERT_SUCCESS(mkdir("/tmp/proc-host", 0755)); + ASSERT_SUCCESS(mount("proc", "/tmp/proc-host", "proc", 0, "pidns=/proc/self/ns/pid")); + ASSERT_SUCCESS(access("/tmp/proc-host/self/", X_OK)); + + ASSERT_SUCCESS(mkdir("/tmp/proc-dummy", 0755)); + ASSERT_SUCCESS(mount("proc", "/tmp/proc-dummy", "proc", 0, "pidns=/tmp/dummy-pidns")); + ASSERT_ERRNO_EQ(-ENOENT, access("/tmp/proc-dummy/1/", X_OK)); + ASSERT_ERRNO_EQ(-ENOENT, access("/tmp/proc-dummy/self/", X_OK)); +} + +TEST_F(ns, pidns_fsconfig_string_path) +{ + int fsfd = fsopen("proc", FSOPEN_CLOEXEC); + ASSERT_SUCCESS(fsfd); + + ASSERT_SUCCESS(fsconfig(fsfd, FSCONFIG_SET_STRING, "pidns", "/tmp/dummy-pidns", 0)); + ASSERT_SUCCESS(fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0)); + + int mountfd = fsmount(fsfd, FSMOUNT_CLOEXEC, 0); + ASSERT_SUCCESS(mountfd); + + ASSERT_ERRNO_EQ(-ENOENT, faccessat(mountfd, "1/", X_OK, 0)); + ASSERT_ERRNO_EQ(-ENOENT, faccessat(mountfd, "self/", X_OK, 0)); + + ASSERT_SUCCESS(close(fsfd)); + ASSERT_SUCCESS(close(mountfd)); +} + +TEST_F(ns, pidns_fsconfig_fd) +{ + int fsfd = fsopen("proc", FSOPEN_CLOEXEC); + ASSERT_SUCCESS(fsfd); + + ASSERT_SUCCESS(fsconfig(fsfd, FSCONFIG_SET_FD, "pidns", NULL, self->dummy_pidns)); + ASSERT_SUCCESS(fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0)); + + int mountfd = fsmount(fsfd, FSMOUNT_CLOEXEC, 0); + ASSERT_SUCCESS(mountfd); + + ASSERT_ERRNO_EQ(-ENOENT, faccessat(mountfd, "1/", X_OK, 0)); + ASSERT_ERRNO_EQ(-ENOENT, faccessat(mountfd, "self/", X_OK, 0)); + + ASSERT_SUCCESS(close(fsfd)); + ASSERT_SUCCESS(close(mountfd)); +} + +TEST_F(ns, pidns_reconfigure_remount) +{ + ASSERT_SUCCESS(mkdir("/tmp/proc", 0755)); + ASSERT_SUCCESS(mount("proc", "/tmp/proc", "proc", 0, "")); + + ASSERT_SUCCESS(access("/tmp/proc/1/", X_OK)); + ASSERT_SUCCESS(access("/tmp/proc/self/", X_OK)); + + ASSERT_ERRNO_EQ(-EBUSY, mount(NULL, "/tmp/proc", NULL, MS_REMOUNT, "pidns=/tmp/dummy-pidns")); + + ASSERT_SUCCESS(access("/tmp/proc/1/", X_OK)); + ASSERT_SUCCESS(access("/tmp/proc/self/", X_OK)); +} + +TEST_F(ns, pidns_reconfigure_fsconfig_string_path) +{ + int fsfd = fsopen("proc", FSOPEN_CLOEXEC); + ASSERT_SUCCESS(fsfd); + + ASSERT_SUCCESS(fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0)); + + int mountfd = fsmount(fsfd, FSMOUNT_CLOEXEC, 0); + ASSERT_SUCCESS(mountfd); + + ASSERT_SUCCESS(faccessat(mountfd, "1/", X_OK, 0)); + ASSERT_SUCCESS(faccessat(mountfd, "self/", X_OK, 0)); + + ASSERT_ERRNO_EQ(-EBUSY, fsconfig(fsfd, FSCONFIG_SET_STRING, "pidns", "/tmp/dummy-pidns", 0)); + ASSERT_SUCCESS(fsconfig(fsfd, FSCONFIG_CMD_RECONFIGURE, NULL, NULL, 0)); /* noop */ + + ASSERT_SUCCESS(faccessat(mountfd, "1/", X_OK, 0)); + ASSERT_SUCCESS(faccessat(mountfd, "self/", X_OK, 0)); + + ASSERT_SUCCESS(close(fsfd)); + ASSERT_SUCCESS(close(mountfd)); +} + +TEST_F(ns, pidns_reconfigure_fsconfig_fd) +{ + int fsfd = fsopen("proc", FSOPEN_CLOEXEC); + ASSERT_SUCCESS(fsfd); + + ASSERT_SUCCESS(fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0)); + + int mountfd = fsmount(fsfd, FSMOUNT_CLOEXEC, 0); + ASSERT_SUCCESS(mountfd); + + ASSERT_SUCCESS(faccessat(mountfd, "1/", X_OK, 0)); + ASSERT_SUCCESS(faccessat(mountfd, "self/", X_OK, 0)); + + ASSERT_ERRNO_EQ(-EBUSY, fsconfig(fsfd, FSCONFIG_SET_FD, "pidns", NULL, self->dummy_pidns)); + ASSERT_SUCCESS(fsconfig(fsfd, FSCONFIG_CMD_RECONFIGURE, NULL, NULL, 0)); /* noop */ + + ASSERT_SUCCESS(faccessat(mountfd, "1/", X_OK, 0)); + ASSERT_SUCCESS(faccessat(mountfd, "self/", X_OK, 0)); + + ASSERT_SUCCESS(close(fsfd)); + ASSERT_SUCCESS(close(mountfd)); +} + +int is_same_inode(int fd1, int fd2) +{ + struct stat stat1, stat2; + + assert(fstat(fd1, &stat1) == 0); + assert(fstat(fd2, &stat2) == 0); + + return stat1.st_ino == stat2.st_ino && stat1.st_dev == stat2.st_dev; +} + +#define PROCFS_IOCTL_MAGIC 'f' +#define PROCFS_GET_PID_NAMESPACE _IO(PROCFS_IOCTL_MAGIC, 1) + +TEST_F(ns, get_pidns_ioctl) +{ + int fsfd = fsopen("proc", FSOPEN_CLOEXEC); + ASSERT_SUCCESS(fsfd); + + ASSERT_SUCCESS(fsconfig(fsfd, FSCONFIG_SET_FD, "pidns", NULL, self->dummy_pidns)); + ASSERT_SUCCESS(fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0)); + + int mountfd = fsmount(fsfd, FSMOUNT_CLOEXEC, 0); + ASSERT_SUCCESS(mountfd); + + /* fsmount returns an O_PATH, which ioctl(2) doesn't accept. */ + int new_mountfd = openat(mountfd, ".", O_RDONLY|O_DIRECTORY|O_CLOEXEC); + ASSERT_SUCCESS(new_mountfd); + + ASSERT_SUCCESS(close(mountfd)); + mountfd = -EBADF; + + int procfs_pidns = ioctl(new_mountfd, PROCFS_GET_PID_NAMESPACE); + ASSERT_SUCCESS(procfs_pidns); + + ASSERT_NE(self->dummy_pidns, procfs_pidns); + ASSERT_FALSE(is_same_inode(self->host_pidns, procfs_pidns)); + ASSERT_TRUE(is_same_inode(self->dummy_pidns, procfs_pidns)); + + ASSERT_SUCCESS(close(fsfd)); + ASSERT_SUCCESS(close(new_mountfd)); + ASSERT_SUCCESS(close(procfs_pidns)); +} + +TEST_HARNESS_MAIN