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-rw-r--r--sys-utils/nsenter.c150
1 files changed, 134 insertions, 16 deletions
diff --git a/sys-utils/nsenter.c b/sys-utils/nsenter.c
index 56dbf17..8f7bac9 100644
--- a/sys-utils/nsenter.c
+++ b/sys-utils/nsenter.c
@@ -1,22 +1,14 @@
/*
- * nsenter(1) - command-line interface for setns(2)
- *
- * Copyright (C) 2012-2013 Eric Biederman <ebiederm@xmission.com>
+ * SPDX-License-Identifier: GPL-2.0-only
*
* 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>
@@ -30,6 +22,15 @@
#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>
@@ -45,6 +46,9 @@
#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;
@@ -91,22 +95,25 @@ static void __attribute__((__noreturn__)) usage(void)
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);
- printf(USAGE_HELP_OPTIONS(24));
- printf(USAGE_MAN_TAIL("nsenter(1)"));
+ fprintf(out, USAGE_HELP_OPTIONS(24));
+ fprintf(out, USAGE_MAN_TAIL("nsenter(1)"));
exit(EXIT_SUCCESS);
}
@@ -116,6 +123,34 @@ 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)
{
@@ -164,6 +199,55 @@ static int get_ns_ino(const char *path, ino_t *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];
@@ -232,7 +316,9 @@ static void continue_as_child(void)
int main(int argc, char *argv[])
{
enum {
- OPT_PRESERVE_CRED = CHAR_MAX + 1
+ OPT_PRESERVE_CRED = CHAR_MAX + 1,
+ OPT_KEEPCAPS,
+ OPT_USER_PARENT,
};
static const struct option longopts[] = {
{ "all", no_argument, NULL, 'a' },
@@ -254,7 +340,10 @@ int main(int argc, char *argv[])
{ "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
@@ -269,11 +358,13 @@ int main(int argc, char *argv[])
struct namespace_file *nsfile;
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_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;
@@ -285,7 +376,7 @@ int main(int argc, char *argv[])
close_stdout_atexit();
while ((c =
- getopt_long(argc, argv, "+ahVt:m::u::i::n::p::C::U::T::S:G:r::w::W::eFZ",
+ 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);
@@ -363,6 +454,9 @@ int main(int argc, char *argv[])
case 'F':
do_fork = 0;
break;
+ case 'c':
+ do_join_cgroup = true;
+ break;
case 'r':
if (optarg)
open_target_fd(&root_fd, "root", optarg);
@@ -384,6 +478,12 @@ int main(int argc, char *argv[])
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;
@@ -441,6 +541,17 @@ int main(int argc, char *argv[])
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();
/*
* Update namespaces variable to contain all requested namespaces
@@ -542,6 +653,10 @@ int main(int argc, char *argv[])
close(env_fd);
}
+ // Join into the target cgroup
+ if (cgroup_procs_fd >= 0)
+ join_into_cgroup();
+
if (uid_gid_fd >= 0) {
struct stat st;
@@ -569,6 +684,9 @@ int main(int argc, char *argv[])
err(EXIT_FAILURE, _("setuid failed"));
}
+ if (keepcaps && (namespaces & CLONE_NEWUSER))
+ cap_permitted_to_ambient();
+
if (optind < argc) {
execvp(argv[optind], argv + optind);
errexec(argv[optind]);
generated by cgit v1.2.3 (git 2.39.1) at 2024-09-06 08:22:15 +0000