/*
- * nsenter(1) - command-line interface for setns(2)
- *
- * Copyright (C) 2012-2013 Eric Biederman <ebiederm@xmission.com>
+ * SPDX-License-Identifier: GPL-2.0
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; version 2.
*
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
+ * Copyright (C) 2012-2023 Eric Biederman <ebiederm@xmission.com>
*
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ * nsenter(1) - command-line interface for setns(2)
*/
-
#include <dirent.h>
#include <errno.h>
#include <getopt.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <grp.h>
+#include <sys/stat.h>
+#include <sys/statfs.h>
+
+#include <sys/ioctl.h>
+#ifdef HAVE_LINUX_NSFS_H
+# include <linux/nsfs.h>
+#endif
+#ifndef NS_GET_USERNS
+# define NS_GET_USERNS _IO(0xb7, 0x1)
+#endif
+
+#ifdef HAVE_LIBSELINUX
+# include <selinux/selinux.h>
+#endif
#include "strutils.h"
#include "nls.h"
#include "closestream.h"
#include "namespace.h"
#include "exec_shell.h"
+#include "optutils.h"
+#include "xalloc.h"
+#include "all-io.h"
+#include "env.h"
+#include "caputils.h"
+#include "statfs_magic.h"
+#include "pathnames.h"
static struct namespace_file {
int nstype;
} namespace_files[] = {
/* Careful the order is significant in this array.
*
- * The user namespace comes first, so that it is entered
- * first. This gives an unprivileged user the potential to
- * enter the other namespaces.
+ * The user namespace comes either first or last: first if
+ * you're using it to increase your privilege and last if
+ * you're using it to decrease. We enter the namespaces in
+ * two passes starting initially from offset 1 and then offset
+ * 0 if that fails.
*/
- { .nstype = CLONE_NEWUSER, .name = "ns/user", .fd = -1 },
- { .nstype = CLONE_NEWIPC, .name = "ns/ipc", .fd = -1 },
- { .nstype = CLONE_NEWUTS, .name = "ns/uts", .fd = -1 },
- { .nstype = CLONE_NEWNET, .name = "ns/net", .fd = -1 },
- { .nstype = CLONE_NEWPID, .name = "ns/pid", .fd = -1 },
- { .nstype = CLONE_NEWNS, .name = "ns/mnt", .fd = -1 },
+ { .nstype = CLONE_NEWUSER, .name = "ns/user", .fd = -1 },
+ { .nstype = CLONE_NEWCGROUP,.name = "ns/cgroup", .fd = -1 },
+ { .nstype = CLONE_NEWIPC, .name = "ns/ipc", .fd = -1 },
+ { .nstype = CLONE_NEWUTS, .name = "ns/uts", .fd = -1 },
+ { .nstype = CLONE_NEWNET, .name = "ns/net", .fd = -1 },
+ { .nstype = CLONE_NEWPID, .name = "ns/pid", .fd = -1 },
+ { .nstype = CLONE_NEWNS, .name = "ns/mnt", .fd = -1 },
+ { .nstype = CLONE_NEWTIME, .name = "ns/time", .fd = -1 },
{ .nstype = 0, .name = NULL, .fd = -1 }
};
-static void usage(int status)
+static void __attribute__((__noreturn__)) usage(void)
{
- FILE *out = status == EXIT_SUCCESS ? stdout : stderr;
+ FILE *out = stdout;
fputs(USAGE_HEADER, out);
- fprintf(out, _(" %s [options] <program> [args...]\n"),
+ fprintf(out, _(" %s [options] [<program> [<argument>...]]\n"),
program_invocation_short_name);
+ fputs(USAGE_SEPARATOR, out);
+ fputs(_("Run a program with namespaces of other processes.\n"), out);
+
fputs(USAGE_OPTIONS, out);
+ fputs(_(" -a, --all enter all namespaces\n"), out);
fputs(_(" -t, --target <pid> target process to get namespaces from\n"), out);
- fputs(_(" -m, --mount [=<file>] enter mount namespace\n"), out);
- fputs(_(" -u, --uts [=<file>] enter UTS namespace (hostname etc)\n"), out);
- fputs(_(" -i, --ipc [=<file>] enter System V IPC namespace\n"), out);
- fputs(_(" -n, --net [=<file>] enter network namespace\n"), out);
- fputs(_(" -p, --pid [=<file>] enter pid namespace\n"), out);
- fputs(_(" -U, --user [=<file>] enter user namespace\n"), out);
- fputs(_(" -S, --setuid <uid> set uid in user namespace\n"), out);
- fputs(_(" -G, --setgid <gid> set gid in user namespace\n"), out);
- fputs(_(" -r, --root [=<dir>] set the root directory\n"), out);
- fputs(_(" -w, --wd [=<dir>] set the working directory\n"), out);
+ fputs(_(" -m, --mount[=<file>] enter mount namespace\n"), out);
+ fputs(_(" -u, --uts[=<file>] enter UTS namespace (hostname etc)\n"), out);
+ fputs(_(" -i, --ipc[=<file>] enter System V IPC namespace\n"), out);
+ fputs(_(" -n, --net[=<file>] enter network namespace\n"), out);
+ fputs(_(" -p, --pid[=<file>] enter pid namespace\n"), out);
+ fputs(_(" -C, --cgroup[=<file>] enter cgroup namespace\n"), out);
+ fputs(_(" -U, --user[=<file>] enter user namespace\n"), out);
+ fputs(_(" --user-parent enter parent user namespace\n"), out);
+ fputs(_(" -T, --time[=<file>] enter time namespace\n"), out);
+ fputs(_(" -S, --setuid[=<uid>] set uid in entered namespace\n"), out);
+ fputs(_(" -G, --setgid[=<gid>] set gid in entered namespace\n"), out);
+ fputs(_(" --preserve-credentials do not touch uids or gids\n"), out);
+ fputs(_(" --keep-caps retain capabilities granted in user namespaces\n"), out);
+ fputs(_(" -r, --root[=<dir>] set the root directory\n"), out);
+ fputs(_(" -w, --wd[=<dir>] set the working directory\n"), out);
+ fputs(_(" -W, --wdns <dir> set the working directory in namespace\n"), out);
+ fputs(_(" -e, --env inherit environment variables from target process\n"), out);
fputs(_(" -F, --no-fork do not fork before exec'ing <program>\n"), out);
+ fputs(_(" -c, --join-cgroup join the cgroup of the target process\n"), out);
+#ifdef HAVE_LIBSELINUX
+ fputs(_(" -Z, --follow-context set SELinux context according to --target PID\n"), out);
+#endif
fputs(USAGE_SEPARATOR, out);
- fputs(USAGE_HELP, out);
- fputs(USAGE_VERSION, out);
+ fprintf(out, USAGE_HELP_OPTIONS(24));
fprintf(out, USAGE_MAN_TAIL("nsenter(1)"));
- exit(status);
+ exit(EXIT_SUCCESS);
}
static pid_t namespace_target_pid = 0;
static int root_fd = -1;
static int wd_fd = -1;
+static int env_fd = -1;
+static int uid_gid_fd = -1;
+static int cgroup_procs_fd = -1;
+
+static void set_parent_user_ns_fd(void)
+{
+ struct namespace_file *nsfile = NULL;
+ struct namespace_file *user_nsfile = NULL;
+ int parent_ns = -1;
+
+ for (nsfile = namespace_files; nsfile->nstype; nsfile++) {
+ if (nsfile->nstype == CLONE_NEWUSER)
+ user_nsfile = nsfile;
+
+ if (nsfile->fd == -1)
+ continue;
+
+ parent_ns = ioctl(nsfile->fd, NS_GET_USERNS);
+ if (parent_ns < 0)
+ err(EXIT_FAILURE, _("failed to open parent ns of %s"), nsfile->name);
+
+ break;
+ }
+
+ if (parent_ns < 0)
+ errx(EXIT_FAILURE, _("no namespaces to get parent of"));
+ if (user_nsfile)
+ user_nsfile->fd = parent_ns;
+}
+
static void open_target_fd(int *fd, const char *type, const char *path)
{
assert(nsfile->nstype);
}
+static int get_ns_ino(const char *path, ino_t *ino)
+{
+ struct stat st;
+
+ if (stat(path, &st) != 0)
+ return -errno;
+ *ino = st.st_ino;
+ return 0;
+}
+
+static void open_cgroup_procs(void)
+{
+ char *buf = NULL, *path = NULL, *p;
+ int cgroup_fd = 0;
+ char fdpath[PATH_MAX];
+
+ open_target_fd(&cgroup_fd, "cgroup", optarg);
+
+ if (read_all_alloc(cgroup_fd, &buf) < 1)
+ err(EXIT_FAILURE, _("failed to get cgroup path"));
+
+ p = strtok(buf, "\n");
+ if (p)
+ path = strrchr(p, ':');
+ if (!path)
+ err(EXIT_FAILURE, _("failed to get cgroup path"));
+ path++;
+
+ snprintf(fdpath, sizeof(fdpath), _PATH_SYS_CGROUP "/%s/cgroup.procs", path);
+
+ if ((cgroup_procs_fd = open(fdpath, O_WRONLY | O_APPEND)) < 0)
+ err(EXIT_FAILURE, _("failed to open cgroup.procs"));
+
+ free(buf);
+}
+
+static int is_cgroup2(void)
+{
+ struct statfs fs_stat;
+ int rc;
+
+ rc = statfs(_PATH_SYS_CGROUP, &fs_stat);
+ if (rc)
+ err(EXIT_FAILURE, _("statfs %s failed"), _PATH_SYS_CGROUP);
+ return F_TYPE_EQUAL(fs_stat.f_type, STATFS_CGROUP2_MAGIC);
+}
+
+static void join_into_cgroup(void)
+{
+ pid_t pid;
+ char buf[ sizeof(stringify_value(UINT32_MAX)) ];
+ int len;
+
+ pid = getpid();
+ len = snprintf(buf, sizeof(buf), "%zu", (size_t) pid);
+ if (write_all(cgroup_procs_fd, buf, len))
+ err(EXIT_FAILURE, _("write cgroup.procs failed"));
+}
+
+static int is_usable_namespace(pid_t target, const struct namespace_file *nsfile)
+{
+ char path[PATH_MAX];
+ ino_t my_ino = 0;
+ int rc;
+
+ /* Check NS accessibility */
+ snprintf(path, sizeof(path), "/proc/%u/%s", getpid(), nsfile->name);
+ rc = get_ns_ino(path, &my_ino);
+ if (rc == -ENOENT)
+ return false; /* Unsupported NS */
+
+ /* It is not permitted to use setns(2) to reenter the caller's
+ * current user namespace; see setns(2) man page for more details.
+ */
+ if (nsfile->nstype & CLONE_NEWUSER) {
+ ino_t target_ino = 0;
+
+ snprintf(path, sizeof(path), "/proc/%u/%s", target, nsfile->name);
+ if (get_ns_ino(path, &target_ino) != 0)
+ err(EXIT_FAILURE, _("stat of %s failed"), path);
+
+ if (my_ino == target_ino)
+ return false;
+ }
+
+ return true; /* All pass */
+}
+
static void continue_as_child(void)
{
- pid_t child = fork();
+ pid_t child;
int status;
pid_t ret;
+ /* Clear any inherited settings */
+ signal(SIGCHLD, SIG_DFL);
+
+ child = fork();
if (child < 0)
err(EXIT_FAILURE, _("fork failed"));
int main(int argc, char *argv[])
{
+ enum {
+ OPT_PRESERVE_CRED = CHAR_MAX + 1,
+ OPT_KEEPCAPS,
+ OPT_USER_PARENT,
+ };
static const struct option longopts[] = {
+ { "all", no_argument, NULL, 'a' },
{ "help", no_argument, NULL, 'h' },
{ "version", no_argument, NULL, 'V'},
{ "target", required_argument, NULL, 't' },
{ "net", optional_argument, NULL, 'n' },
{ "pid", optional_argument, NULL, 'p' },
{ "user", optional_argument, NULL, 'U' },
+ { "cgroup", optional_argument, NULL, 'C' },
+ { "time", optional_argument, NULL, 'T' },
{ "setuid", required_argument, NULL, 'S' },
{ "setgid", required_argument, NULL, 'G' },
{ "root", optional_argument, NULL, 'r' },
{ "wd", optional_argument, NULL, 'w' },
+ { "wdns", optional_argument, NULL, 'W' },
+ { "env", no_argument, NULL, 'e' },
{ "no-fork", no_argument, NULL, 'F' },
+ { "join-cgroup", no_argument, NULL, 'c'},
+ { "preserve-credentials", no_argument, NULL, OPT_PRESERVE_CRED },
+ { "keep-caps", no_argument, NULL, OPT_KEEPCAPS },
+ { "user-parent", no_argument, NULL, OPT_USER_PARENT},
+#ifdef HAVE_LIBSELINUX
+ { "follow-context", no_argument, NULL, 'Z' },
+#endif
{ NULL, 0, NULL, 0 }
};
+ static const ul_excl_t excl[] = { /* rows and cols in ASCII order */
+ { 'W', 'w' },
+ { 0 }
+ };
+ int excl_st[ARRAY_SIZE(excl)] = UL_EXCL_STATUS_INIT;
struct namespace_file *nsfile;
- int c, namespaces = 0;
- bool do_rd = false, do_wd = false;
+ int c, pass, namespaces = 0, setgroups_nerrs = 0, preserve_cred = 0;
+ bool do_rd = false, do_wd = false, do_uid = false, force_uid = false,
+ do_gid = false, force_gid = false, do_env = false, do_all = false,
+ do_join_cgroup = false, do_user_parent = false;
int do_fork = -1; /* unknown yet */
+ char *wdns = NULL;
uid_t uid = 0;
gid_t gid = 0;
+ int keepcaps = 0;
+ struct ul_env_list *envls;
+#ifdef HAVE_LIBSELINUX
+ bool selinux = 0;
+#endif
setlocale(LC_ALL, "");
bindtextdomain(PACKAGE, LOCALEDIR);
textdomain(PACKAGE);
- atexit(close_stdout);
+ close_stdout_atexit();
while ((c =
- getopt_long(argc, argv, "hVt:m::u::i::n::p::U::S:G:r::w::F",
+ getopt_long(argc, argv, "+ahVt:m::u::i::n::p::C::U::T::S:G:r::w::W::ecFZ",
longopts, NULL)) != -1) {
+
+ err_exclusive_options(c, longopts, excl, excl_st);
+
switch (c) {
- case 'h':
- usage(EXIT_SUCCESS);
- case 'V':
- printf(UTIL_LINUX_VERSION);
- return EXIT_SUCCESS;
+ case 'a':
+ do_all = true;
+ break;
case 't':
namespace_target_pid =
strtoul_or_err(optarg, _("failed to parse pid"));
else
namespaces |= CLONE_NEWPID;
break;
+ case 'C':
+ if (optarg)
+ open_namespace_fd(CLONE_NEWCGROUP, optarg);
+ else
+ namespaces |= CLONE_NEWCGROUP;
+ break;
case 'U':
if (optarg)
open_namespace_fd(CLONE_NEWUSER, optarg);
else
namespaces |= CLONE_NEWUSER;
break;
+ case 'T':
+ if (optarg)
+ open_namespace_fd(CLONE_NEWTIME, optarg);
+ else
+ namespaces |= CLONE_NEWTIME;
+ break;
case 'S':
- uid = strtoul_or_err(optarg, _("failed to parse uid"));
+ if (strcmp(optarg, "follow") == 0)
+ do_uid = true;
+ else
+ uid = strtoul_or_err(optarg, _("failed to parse uid"));
+ force_uid = true;
break;
case 'G':
- gid = strtoul_or_err(optarg, _("failed to parse gid"));
+ if (strcmp(optarg, "follow") == 0)
+ do_gid = true;
+ else
+ gid = strtoul_or_err(optarg, _("failed to parse gid"));
+ force_gid = true;
break;
case 'F':
do_fork = 0;
break;
+ case 'c':
+ do_join_cgroup = true;
+ break;
case 'r':
if (optarg)
open_target_fd(&root_fd, "root", optarg);
else
do_wd = true;
break;
+ case 'W':
+ wdns = optarg;
+ break;
+ case 'e':
+ do_env = true;
+ break;
+ case OPT_PRESERVE_CRED:
+ preserve_cred = 1;
+ break;
+ case OPT_KEEPCAPS:
+ keepcaps = 1;
+ break;
+ case OPT_USER_PARENT:
+ do_user_parent = true;
+ break;
+#ifdef HAVE_LIBSELINUX
+ case 'Z':
+ selinux = 1;
+ break;
+#endif
+ case 'h':
+ usage();
+ case 'V':
+ print_version(EXIT_SUCCESS);
default:
- usage(EXIT_FAILURE);
+ errtryhelp(EXIT_FAILURE);
+ }
+ }
+
+#ifdef HAVE_LIBSELINUX
+ if (selinux && is_selinux_enabled() > 0) {
+ char *scon = NULL;
+
+ if (!namespace_target_pid)
+ errx(EXIT_FAILURE, _("no target PID specified for --follow-context"));
+ if (getpidcon(namespace_target_pid, &scon) < 0)
+ errx(EXIT_FAILURE, _("failed to get %d SELinux context"),
+ (int) namespace_target_pid);
+ if (setexeccon(scon) < 0)
+ errx(EXIT_FAILURE, _("failed to set exec context to '%s'"), scon);
+ freecon(scon);
+ }
+#endif
+
+ if (do_all) {
+ if (!namespace_target_pid)
+ errx(EXIT_FAILURE, _("no target PID specified for --all"));
+ for (nsfile = namespace_files; nsfile->nstype; nsfile++) {
+ if (nsfile->fd >= 0)
+ continue; /* namespace already specified */
+
+ if (!is_usable_namespace(namespace_target_pid, nsfile))
+ continue;
+
+ namespaces |= nsfile->nstype;
}
}
open_target_fd(&root_fd, "root", NULL);
if (do_wd)
open_target_fd(&wd_fd, "cwd", NULL);
+ if (do_env)
+ open_target_fd(&env_fd, "environ", NULL);
+ if (do_uid || do_gid)
+ open_target_fd(&uid_gid_fd, "", NULL);
+ if (do_join_cgroup) {
+ if (!is_cgroup2())
+ errx(EXIT_FAILURE, _("--join-cgroup is only supported in cgroup v2"));
+ open_cgroup_procs();
+ }
+
+ /*
+ * Get parent userns from any available ns.
+ */
+ if (do_user_parent)
+ set_parent_user_ns_fd();
/*
- * Now that we know which namespaces we want to enter, enter them.
+ * Update namespaces variable to contain all requested namespaces
*/
for (nsfile = namespace_files; nsfile->nstype; nsfile++) {
if (nsfile->fd < 0)
continue;
- if (nsfile->nstype == CLONE_NEWPID && do_fork == -1)
- do_fork = 1;
- if (setns(nsfile->fd, nsfile->nstype))
- err(EXIT_FAILURE,
- _("reassociate to namespace '%s' failed"),
- nsfile->name);
- close(nsfile->fd);
- nsfile->fd = -1;
+ namespaces |= nsfile->nstype;
+ }
+
+ /* for user namespaces we always set UID and GID (default is 0)
+ * and clear root's groups if --preserve-credentials is no specified */
+ if ((namespaces & CLONE_NEWUSER) && !preserve_cred) {
+ force_uid = true, force_gid = true;
+
+ /* We call setgroups() before and after we enter user namespace,
+ * let's complain only if both fail */
+ if (setgroups(0, NULL) != 0)
+ setgroups_nerrs++;
+ }
+
+ /*
+ * Now that we know which namespaces we want to enter, enter
+ * them. Do this in two passes, not entering the user
+ * namespace on the first pass. So if we're deprivileging the
+ * container we'll enter the user namespace last and if we're
+ * privileging it then we enter the user namespace first
+ * (because the initial setns will fail).
+ */
+ for (pass = 0; pass < 2; pass ++) {
+ for (nsfile = namespace_files + 1 - pass; nsfile->nstype; nsfile++) {
+ if (nsfile->fd < 0)
+ continue;
+ if (nsfile->nstype == CLONE_NEWPID && do_fork == -1)
+ do_fork = 1;
+ if (setns(nsfile->fd, nsfile->nstype)) {
+ if (pass != 0)
+ err(EXIT_FAILURE,
+ _("reassociate to namespace '%s' failed"),
+ nsfile->name);
+ else
+ continue;
+ }
+
+ close(nsfile->fd);
+ nsfile->fd = -1;
+ }
}
/* Remember the current working directory if I'm not changing it */
- if (root_fd >= 0 && wd_fd < 0) {
+ if (root_fd >= 0 && wd_fd < 0 && wdns == NULL) {
wd_fd = open(".", O_RDONLY);
if (wd_fd < 0)
err(EXIT_FAILURE,
if (chroot(".") < 0)
err(EXIT_FAILURE, _("chroot failed"));
+ if (chdir("/"))
+ err(EXIT_FAILURE, _("cannot change directory to %s"), "/");
close(root_fd);
root_fd = -1;
}
+ /* working directory specified as in-namespace path */
+ if (wdns) {
+ wd_fd = open(wdns, O_RDONLY);
+ if (wd_fd < 0)
+ err(EXIT_FAILURE,
+ _("cannot open current working directory"));
+ }
+
/* Change the working directory */
if (wd_fd >= 0) {
if (fchdir(wd_fd) < 0)
wd_fd = -1;
}
+ /* Pass environment variables of the target process to the spawned process */
+ if (env_fd >= 0) {
+ if ((envls = env_from_fd(env_fd)) == NULL)
+ err(EXIT_FAILURE, _("failed to get environment variables"));
+ clearenv();
+ if (env_list_setenv(envls) < 0)
+ err(EXIT_FAILURE, _("failed to set environment variables"));
+ env_list_free(envls);
+ close(env_fd);
+ }
+
+ // Join into the target cgroup
+ if (cgroup_procs_fd >= 0)
+ join_into_cgroup();
+
+ if (uid_gid_fd >= 0) {
+ struct stat st;
+
+ if (fstat(uid_gid_fd, &st) > 0)
+ err(EXIT_FAILURE, _("can not get process stat"));
+
+ close(uid_gid_fd);
+ uid_gid_fd = -1;
+
+ if (do_uid)
+ uid = st.st_uid;
+ if (do_gid)
+ gid = st.st_gid;
+ }
+
if (do_fork == 1)
continue_as_child();
- if (namespaces & CLONE_NEWUSER) {
- if (setgroups(0, NULL)) /* drop supplementary groups */
+ if (force_uid || force_gid) {
+ if (force_gid && setgroups(0, NULL) != 0 && setgroups_nerrs) /* drop supplementary groups */
err(EXIT_FAILURE, _("setgroups failed"));
- if (setgid(gid) < 0)
+ if (force_gid && setgid(gid) < 0) /* change GID */
err(EXIT_FAILURE, _("setgid failed"));
- if (setuid(uid) < 0)
+ if (force_uid && setuid(uid) < 0) /* change UID */
err(EXIT_FAILURE, _("setuid failed"));
}
+ if (keepcaps && (namespaces & CLONE_NEWUSER))
+ cap_permitted_to_ambient();
+
if (optind < argc) {
execvp(argv[optind], argv + optind);
- err(EXIT_FAILURE, _("failed to execute %s"), argv[optind]);
+ errexec(argv[optind]);
}
exec_shell();
}
projects / thirdparty / util-linux.git / blobdiff