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-rw-r--r--sys-utils/unshare.c710
1 files changed, 710 insertions, 0 deletions
diff --git a/sys-utils/unshare.c b/sys-utils/unshare.c
new file mode 100644
index 0000000..cd5fe68
--- /dev/null
+++ b/sys-utils/unshare.c
@@ -0,0 +1,710 @@
+/*
+ * unshare(1) - command-line interface for unshare(2)
+ *
+ * Copyright (C) 2009 Mikhail Gusarov <dottedmag@dottedmag.net>
+ *
+ * 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; either version 2, or (at your option) any
+ * later version.
+ *
+ * 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.
+ *
+ * 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.
+ */
+
+#include <errno.h>
+#include <getopt.h>
+#include <sched.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/wait.h>
+#include <sys/mount.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/prctl.h>
+#include <grp.h>
+
+/* we only need some defines missing in sys/mount.h, no libmount linkage */
+#include <libmount.h>
+
+#include "nls.h"
+#include "c.h"
+#include "caputils.h"
+#include "closestream.h"
+#include "namespace.h"
+#include "exec_shell.h"
+#include "xalloc.h"
+#include "pathnames.h"
+#include "all-io.h"
+#include "signames.h"
+#include "strutils.h"
+#include "pwdutils.h"
+
+/* synchronize parent and child by pipe */
+#define PIPE_SYNC_BYTE 0x06
+
+/* 'private' is kernel default */
+#define UNSHARE_PROPAGATION_DEFAULT (MS_REC | MS_PRIVATE)
+
+/* /proc namespace files and mountpoints for binds */
+static struct namespace_file {
+ int type; /* CLONE_NEW* */
+ const char *name; /* ns/<type> */
+ const char *target; /* user specified target for bind mount */
+} namespace_files[] = {
+ { .type = CLONE_NEWUSER, .name = "ns/user" },
+ { .type = CLONE_NEWCGROUP,.name = "ns/cgroup" },
+ { .type = CLONE_NEWIPC, .name = "ns/ipc" },
+ { .type = CLONE_NEWUTS, .name = "ns/uts" },
+ { .type = CLONE_NEWNET, .name = "ns/net" },
+ { .type = CLONE_NEWPID, .name = "ns/pid_for_children" },
+ { .type = CLONE_NEWNS, .name = "ns/mnt" },
+ { .type = CLONE_NEWTIME, .name = "ns/time_for_children" },
+ { .name = NULL }
+};
+
+static int npersists; /* number of persistent namespaces */
+
+enum {
+ SETGROUPS_NONE = -1,
+ SETGROUPS_DENY = 0,
+ SETGROUPS_ALLOW = 1,
+};
+
+static const char *setgroups_strings[] =
+{
+ [SETGROUPS_DENY] = "deny",
+ [SETGROUPS_ALLOW] = "allow"
+};
+
+static int setgroups_str2id(const char *str)
+{
+ size_t i;
+
+ for (i = 0; i < ARRAY_SIZE(setgroups_strings); i++)
+ if (strcmp(str, setgroups_strings[i]) == 0)
+ return i;
+
+ errx(EXIT_FAILURE, _("unsupported --setgroups argument '%s'"), str);
+}
+
+static void setgroups_control(int action)
+{
+ const char *file = _PATH_PROC_SETGROUPS;
+ const char *cmd;
+ int fd;
+
+ if (action < 0 || (size_t) action >= ARRAY_SIZE(setgroups_strings))
+ return;
+ cmd = setgroups_strings[action];
+
+ fd = open(file, O_WRONLY);
+ if (fd < 0) {
+ if (errno == ENOENT)
+ return;
+ err(EXIT_FAILURE, _("cannot open %s"), file);
+ }
+
+ if (write_all(fd, cmd, strlen(cmd)))
+ err(EXIT_FAILURE, _("write failed %s"), file);
+ close(fd);
+}
+
+static void map_id(const char *file, uint32_t from, uint32_t to)
+{
+ char *buf;
+ int fd;
+
+ fd = open(file, O_WRONLY);
+ if (fd < 0)
+ err(EXIT_FAILURE, _("cannot open %s"), file);
+
+ xasprintf(&buf, "%u %u 1", from, to);
+ if (write_all(fd, buf, strlen(buf)))
+ err(EXIT_FAILURE, _("write failed %s"), file);
+ free(buf);
+ close(fd);
+}
+
+static unsigned long parse_propagation(const char *str)
+{
+ size_t i;
+ static const struct prop_opts {
+ const char *name;
+ unsigned long flag;
+ } opts[] = {
+ { "slave", MS_REC | MS_SLAVE },
+ { "private", MS_REC | MS_PRIVATE },
+ { "shared", MS_REC | MS_SHARED },
+ { "unchanged", 0 }
+ };
+
+ for (i = 0; i < ARRAY_SIZE(opts); i++) {
+ if (strcmp(opts[i].name, str) == 0)
+ return opts[i].flag;
+ }
+
+ errx(EXIT_FAILURE, _("unsupported propagation mode: %s"), str);
+}
+
+static void set_propagation(unsigned long flags)
+{
+ if (flags == 0)
+ return;
+
+ if (mount("none", "/", NULL, flags, NULL) != 0)
+ err(EXIT_FAILURE, _("cannot change root filesystem propagation"));
+}
+
+
+static int set_ns_target(int type, const char *path)
+{
+ struct namespace_file *ns;
+
+ for (ns = namespace_files; ns->name; ns++) {
+ if (ns->type != type)
+ continue;
+ ns->target = path;
+ npersists++;
+ return 0;
+ }
+
+ return -EINVAL;
+}
+
+static int bind_ns_files(pid_t pid)
+{
+ struct namespace_file *ns;
+ char src[PATH_MAX];
+
+ for (ns = namespace_files; ns->name; ns++) {
+ if (!ns->target)
+ continue;
+
+ snprintf(src, sizeof(src), "/proc/%u/%s", (unsigned) pid, ns->name);
+
+ if (mount(src, ns->target, NULL, MS_BIND, NULL) != 0)
+ err(EXIT_FAILURE, _("mount %s on %s failed"), src, ns->target);
+ }
+
+ return 0;
+}
+
+static ino_t get_mnt_ino(pid_t pid)
+{
+ struct stat st;
+ char path[PATH_MAX];
+
+ snprintf(path, sizeof(path), "/proc/%u/ns/mnt", (unsigned) pid);
+
+ if (stat(path, &st) != 0)
+ err(EXIT_FAILURE, _("cannot stat %s"), path);
+ return st.st_ino;
+}
+
+static void settime(time_t offset, clockid_t clk_id)
+{
+ char buf[sizeof(stringify_value(ULONG_MAX)) * 3];
+ int fd, len;
+
+ len = snprintf(buf, sizeof(buf), "%d %ld 0", clk_id, offset);
+
+ fd = open("/proc/self/timens_offsets", O_WRONLY);
+ if (fd < 0)
+ err(EXIT_FAILURE, _("failed to open /proc/self/timens_offsets"));
+
+ if (write(fd, buf, len) != len)
+ err(EXIT_FAILURE, _("failed to write to /proc/self/timens_offsets"));
+
+ close(fd);
+}
+
+static void bind_ns_files_from_child(pid_t *child, int fds[2])
+{
+ char ch;
+ pid_t ppid = getpid();
+ ino_t ino = get_mnt_ino(ppid);
+
+ if (pipe(fds) < 0)
+ err(EXIT_FAILURE, _("pipe failed"));
+
+ *child = fork();
+
+ switch (*child) {
+ case -1:
+ err(EXIT_FAILURE, _("fork failed"));
+
+ case 0: /* child */
+ close(fds[1]);
+ fds[1] = -1;
+
+ /* wait for parent */
+ if (read_all(fds[0], &ch, 1) != 1 && ch != PIPE_SYNC_BYTE)
+ err(EXIT_FAILURE, _("failed to read pipe"));
+ if (get_mnt_ino(ppid) == ino)
+ exit(EXIT_FAILURE);
+ bind_ns_files(ppid);
+ exit(EXIT_SUCCESS);
+ break;
+
+ default: /* parent */
+ close(fds[0]);
+ fds[0] = -1;
+ break;
+ }
+}
+
+static uid_t get_user(const char *s, const char *err)
+{
+ struct passwd *pw;
+ char *buf = NULL;
+ uid_t ret;
+
+ pw = xgetpwnam(s, &buf);
+ if (pw) {
+ ret = pw->pw_uid;
+ free(pw);
+ free(buf);
+ } else {
+ ret = strtoul_or_err(s, err);
+ }
+
+ return ret;
+}
+
+static gid_t get_group(const char *s, const char *err)
+{
+ struct group *gr;
+ char *buf = NULL;
+ gid_t ret;
+
+ gr = xgetgrnam(s, &buf);
+ if (gr) {
+ ret = gr->gr_gid;
+ free(gr);
+ free(buf);
+ } else {
+ ret = strtoul_or_err(s, err);
+ }
+
+ return ret;
+}
+
+static void __attribute__((__noreturn__)) usage(void)
+{
+ FILE *out = stdout;
+
+ fputs(USAGE_HEADER, out);
+ fprintf(out, _(" %s [options] [<program> [<argument>...]]\n"),
+ program_invocation_short_name);
+
+ fputs(USAGE_SEPARATOR, out);
+ fputs(_("Run a program with some namespaces unshared from the parent.\n"), out);
+
+ fputs(USAGE_OPTIONS, out);
+ fputs(_(" -m, --mount[=<file>] unshare mounts namespace\n"), out);
+ fputs(_(" -u, --uts[=<file>] unshare UTS namespace (hostname etc)\n"), out);
+ fputs(_(" -i, --ipc[=<file>] unshare System V IPC namespace\n"), out);
+ fputs(_(" -n, --net[=<file>] unshare network namespace\n"), out);
+ fputs(_(" -p, --pid[=<file>] unshare pid namespace\n"), out);
+ fputs(_(" -U, --user[=<file>] unshare user namespace\n"), out);
+ fputs(_(" -C, --cgroup[=<file>] unshare cgroup namespace\n"), out);
+ fputs(_(" -T, --time[=<file>] unshare time namespace\n"), out);
+ fputs(USAGE_SEPARATOR, out);
+ fputs(_(" -f, --fork fork before launching <program>\n"), out);
+ fputs(_(" --map-user=<uid>|<name> map current user to uid (implies --user)\n"), out);
+ fputs(_(" --map-group=<gid>|<name> map current group to gid (implies --user)\n"), out);
+ fputs(_(" -r, --map-root-user map current user to root (implies --user)\n"), out);
+ fputs(_(" -c, --map-current-user map current user to itself (implies --user)\n"), out);
+ fputs(USAGE_SEPARATOR, out);
+ fputs(_(" --kill-child[=<signame>] when dying, kill the forked child (implies --fork)\n"
+ " defaults to SIGKILL\n"), out);
+ fputs(_(" --mount-proc[=<dir>] mount proc filesystem first (implies --mount)\n"), out);
+ fputs(_(" --propagation slave|shared|private|unchanged\n"
+ " modify mount propagation in mount namespace\n"), out);
+ fputs(_(" --setgroups allow|deny control the setgroups syscall in user namespaces\n"), out);
+ fputs(_(" --keep-caps retain capabilities granted in user namespaces\n"), out);
+ fputs(USAGE_SEPARATOR, out);
+ fputs(_(" -R, --root=<dir> run the command with root directory set to <dir>\n"), out);
+ fputs(_(" -w, --wd=<dir> change working directory to <dir>\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(_(" --monotonic <offset> set clock monotonic offset (seconds) in time namespaces\n"), out);
+ fputs(_(" --boottime <offset> set clock boottime offset (seconds) in time namespaces\n"), out);
+
+ fputs(USAGE_SEPARATOR, out);
+ printf(USAGE_HELP_OPTIONS(27));
+ printf(USAGE_MAN_TAIL("unshare(1)"));
+
+ exit(EXIT_SUCCESS);
+}
+
+int main(int argc, char *argv[])
+{
+ enum {
+ OPT_MOUNTPROC = CHAR_MAX + 1,
+ OPT_PROPAGATION,
+ OPT_SETGROUPS,
+ OPT_KILLCHILD,
+ OPT_KEEPCAPS,
+ OPT_MONOTONIC,
+ OPT_BOOTTIME,
+ OPT_MAPUSER,
+ OPT_MAPGROUP,
+ };
+ static const struct option longopts[] = {
+ { "help", no_argument, NULL, 'h' },
+ { "version", no_argument, NULL, 'V' },
+
+ { "mount", optional_argument, NULL, 'm' },
+ { "uts", optional_argument, NULL, 'u' },
+ { "ipc", optional_argument, NULL, 'i' },
+ { "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' },
+
+ { "fork", no_argument, NULL, 'f' },
+ { "kill-child", optional_argument, NULL, OPT_KILLCHILD },
+ { "mount-proc", optional_argument, NULL, OPT_MOUNTPROC },
+ { "map-user", required_argument, NULL, OPT_MAPUSER },
+ { "map-group", required_argument, NULL, OPT_MAPGROUP },
+ { "map-root-user", no_argument, NULL, 'r' },
+ { "map-current-user", no_argument, NULL, 'c' },
+ { "propagation", required_argument, NULL, OPT_PROPAGATION },
+ { "setgroups", required_argument, NULL, OPT_SETGROUPS },
+ { "keep-caps", no_argument, NULL, OPT_KEEPCAPS },
+ { "setuid", required_argument, NULL, 'S' },
+ { "setgid", required_argument, NULL, 'G' },
+ { "root", required_argument, NULL, 'R' },
+ { "wd", required_argument, NULL, 'w' },
+ { "monotonic", required_argument, NULL, OPT_MONOTONIC },
+ { "boottime", required_argument, NULL, OPT_BOOTTIME },
+ { NULL, 0, NULL, 0 }
+ };
+
+ int setgrpcmd = SETGROUPS_NONE;
+ int unshare_flags = 0;
+ int c, forkit = 0;
+ uid_t mapuser = -1;
+ gid_t mapgroup = -1;
+ int kill_child_signo = 0; /* 0 means --kill-child was not used */
+ const char *procmnt = NULL;
+ const char *newroot = NULL;
+ const char *newdir = NULL;
+ pid_t pid_bind = 0;
+ pid_t pid = 0;
+ int fds[2];
+ int status;
+ unsigned long propagation = UNSHARE_PROPAGATION_DEFAULT;
+ int force_uid = 0, force_gid = 0;
+ uid_t uid = 0, real_euid = geteuid();
+ gid_t gid = 0, real_egid = getegid();
+ int keepcaps = 0;
+ time_t monotonic = 0;
+ time_t boottime = 0;
+ int force_monotonic = 0;
+ int force_boottime = 0;
+
+ setlocale(LC_ALL, "");
+ bindtextdomain(PACKAGE, LOCALEDIR);
+ textdomain(PACKAGE);
+ close_stdout_atexit();
+
+ while ((c = getopt_long(argc, argv, "+fhVmuinpCTUrR:w:S:G:c", longopts, NULL)) != -1) {
+ switch (c) {
+ case 'f':
+ forkit = 1;
+ break;
+ case 'm':
+ unshare_flags |= CLONE_NEWNS;
+ if (optarg)
+ set_ns_target(CLONE_NEWNS, optarg);
+ break;
+ case 'u':
+ unshare_flags |= CLONE_NEWUTS;
+ if (optarg)
+ set_ns_target(CLONE_NEWUTS, optarg);
+ break;
+ case 'i':
+ unshare_flags |= CLONE_NEWIPC;
+ if (optarg)
+ set_ns_target(CLONE_NEWIPC, optarg);
+ break;
+ case 'n':
+ unshare_flags |= CLONE_NEWNET;
+ if (optarg)
+ set_ns_target(CLONE_NEWNET, optarg);
+ break;
+ case 'p':
+ unshare_flags |= CLONE_NEWPID;
+ if (optarg)
+ set_ns_target(CLONE_NEWPID, optarg);
+ break;
+ case 'U':
+ unshare_flags |= CLONE_NEWUSER;
+ if (optarg)
+ set_ns_target(CLONE_NEWUSER, optarg);
+ break;
+ case 'C':
+ unshare_flags |= CLONE_NEWCGROUP;
+ if (optarg)
+ set_ns_target(CLONE_NEWCGROUP, optarg);
+ break;
+ case 'T':
+ unshare_flags |= CLONE_NEWTIME;
+ if (optarg)
+ set_ns_target(CLONE_NEWTIME, optarg);
+ break;
+ case OPT_MOUNTPROC:
+ unshare_flags |= CLONE_NEWNS;
+ procmnt = optarg ? optarg : "/proc";
+ break;
+ case OPT_MAPUSER:
+ unshare_flags |= CLONE_NEWUSER;
+ mapuser = get_user(optarg, _("failed to parse uid"));
+ break;
+ case OPT_MAPGROUP:
+ unshare_flags |= CLONE_NEWUSER;
+ mapgroup = get_group(optarg, _("failed to parse gid"));
+ break;
+ case 'r':
+ unshare_flags |= CLONE_NEWUSER;
+ mapuser = 0;
+ mapgroup = 0;
+ break;
+ case 'c':
+ unshare_flags |= CLONE_NEWUSER;
+ mapuser = real_euid;
+ mapgroup = real_egid;
+ break;
+ case OPT_SETGROUPS:
+ setgrpcmd = setgroups_str2id(optarg);
+ break;
+ case OPT_PROPAGATION:
+ propagation = parse_propagation(optarg);
+ break;
+ case OPT_KILLCHILD:
+ forkit = 1;
+ if (optarg) {
+ if ((kill_child_signo = signame_to_signum(optarg)) < 0)
+ errx(EXIT_FAILURE, _("unknown signal: %s"),
+ optarg);
+ } else {
+ kill_child_signo = SIGKILL;
+ }
+ break;
+ case OPT_KEEPCAPS:
+ keepcaps = 1;
+ cap_last_cap(); /* Force last cap to be cached before we fork. */
+ break;
+ case 'S':
+ uid = strtoul_or_err(optarg, _("failed to parse uid"));
+ force_uid = 1;
+ break;
+ case 'G':
+ gid = strtoul_or_err(optarg, _("failed to parse gid"));
+ force_gid = 1;
+ break;
+ case 'R':
+ newroot = optarg;
+ break;
+ case 'w':
+ newdir = optarg;
+ break;
+ case OPT_MONOTONIC:
+ monotonic = strtoul_or_err(optarg, _("failed to parse monotonic offset"));
+ force_monotonic = 1;
+ break;
+ case OPT_BOOTTIME:
+ boottime = strtoul_or_err(optarg, _("failed to parse boottime offset"));
+ force_boottime = 1;
+ break;
+
+ case 'h':
+ usage();
+ case 'V':
+ print_version(EXIT_SUCCESS);
+ default:
+ errtryhelp(EXIT_FAILURE);
+ }
+ }
+
+ if ((force_monotonic || force_boottime) && !(unshare_flags & CLONE_NEWTIME))
+ errx(EXIT_FAILURE, _("options --monotonic and --boottime require "
+ "unsharing of a time namespace (-t)"));
+
+ if (npersists && (unshare_flags & CLONE_NEWNS))
+ bind_ns_files_from_child(&pid_bind, fds);
+
+ if (-1 == unshare(unshare_flags))
+ err(EXIT_FAILURE, _("unshare failed"));
+
+ if (force_boottime)
+ settime(boottime, CLOCK_BOOTTIME);
+
+ if (force_monotonic)
+ settime(monotonic, CLOCK_MONOTONIC);
+
+ if (forkit) {
+ signal(SIGINT, SIG_IGN);
+ signal(SIGTERM, SIG_IGN);
+
+ /* force child forking before mountspace binding
+ * so pid_for_children is populated */
+ pid = fork();
+
+ switch(pid) {
+ case -1:
+ err(EXIT_FAILURE, _("fork failed"));
+ case 0: /* child */
+ if (pid_bind && (unshare_flags & CLONE_NEWNS))
+ close(fds[1]);
+ break;
+ default: /* parent */
+ break;
+ }
+ }
+
+ if (npersists && (pid || !forkit)) {
+ /* run in parent */
+ if (pid_bind && (unshare_flags & CLONE_NEWNS)) {
+ int rc;
+ char ch = PIPE_SYNC_BYTE;
+
+ /* signal child we are ready */
+ write_all(fds[1], &ch, 1);
+ close(fds[1]);
+ fds[1] = -1;
+
+ /* wait for bind_ns_files_from_child() */
+ do {
+ rc = waitpid(pid_bind, &status, 0);
+ if (rc < 0) {
+ if (errno == EINTR)
+ continue;
+ err(EXIT_FAILURE, _("waitpid failed"));
+ }
+ if (WIFEXITED(status) &&
+ WEXITSTATUS(status) != EXIT_SUCCESS)
+ return WEXITSTATUS(status);
+ } while (rc < 0);
+ } else
+ /* simple way, just bind */
+ bind_ns_files(getpid());
+ }
+
+ if (pid) {
+ if (waitpid(pid, &status, 0) == -1)
+ err(EXIT_FAILURE, _("waitpid failed"));
+
+ signal(SIGINT, SIG_DFL);
+ signal(SIGTERM, SIG_DFL);
+
+ if (WIFEXITED(status))
+ return WEXITSTATUS(status);
+ if (WIFSIGNALED(status))
+ kill(getpid(), WTERMSIG(status));
+ err(EXIT_FAILURE, _("child exit failed"));
+ }
+
+ if (kill_child_signo != 0 && prctl(PR_SET_PDEATHSIG, kill_child_signo) < 0)
+ err(EXIT_FAILURE, "prctl failed");
+
+ if (mapuser != (uid_t) -1)
+ map_id(_PATH_PROC_UIDMAP, mapuser, real_euid);
+
+ /* Since Linux 3.19 unprivileged writing of /proc/self/gid_map
+ * has been disabled unless /proc/self/setgroups is written
+ * first to permanently disable the ability to call setgroups
+ * in that user namespace. */
+ if (mapgroup != (gid_t) -1) {
+ if (setgrpcmd == SETGROUPS_ALLOW)
+ errx(EXIT_FAILURE, _("options --setgroups=allow and "
+ "--map-group are mutually exclusive"));
+ setgroups_control(SETGROUPS_DENY);
+ map_id(_PATH_PROC_GIDMAP, mapgroup, real_egid);
+ }
+
+ if (setgrpcmd != SETGROUPS_NONE)
+ setgroups_control(setgrpcmd);
+
+ if ((unshare_flags & CLONE_NEWNS) && propagation)
+ set_propagation(propagation);
+
+ if (newroot) {
+ if (chroot(newroot) != 0)
+ err(EXIT_FAILURE,
+ _("cannot change root directory to '%s'"), newroot);
+ newdir = newdir ?: "/";
+ }
+ if (newdir && chdir(newdir))
+ err(EXIT_FAILURE, _("cannot chdir to '%s'"), newdir);
+
+ if (procmnt) {
+ if (!newroot && mount("none", procmnt, NULL, MS_PRIVATE|MS_REC, NULL) != 0)
+ err(EXIT_FAILURE, _("umount %s failed"), procmnt);
+ if (mount("proc", procmnt, "proc", MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL) != 0)
+ err(EXIT_FAILURE, _("mount %s failed"), procmnt);
+ }
+
+ if (force_gid) {
+ if (setgroups(0, NULL) != 0) /* drop supplementary groups */
+ err(EXIT_FAILURE, _("setgroups failed"));
+ if (setgid(gid) < 0) /* change GID */
+ err(EXIT_FAILURE, _("setgid failed"));
+ }
+ if (force_uid && setuid(uid) < 0) /* change UID */
+ err(EXIT_FAILURE, _("setuid failed"));
+
+ /* We use capabilities system calls to propagate the permitted
+ * capabilities into the ambient set because we have already
+ * forked so are in async-signal-safe context. */
+ if (keepcaps && (unshare_flags & CLONE_NEWUSER)) {
+ struct __user_cap_header_struct header = {
+ .version = _LINUX_CAPABILITY_VERSION_3,
+ .pid = 0,
+ };
+
+ struct __user_cap_data_struct payload[_LINUX_CAPABILITY_U32S_3] = {{ 0 }};
+ uint64_t effective, cap;
+
+ if (capget(&header, payload) < 0)
+ err(EXIT_FAILURE, _("capget failed"));
+
+ /* In order the make capabilities ambient, we first need to ensure
+ * that they are all inheritable. */
+ payload[0].inheritable = payload[0].permitted;
+ payload[1].inheritable = payload[1].permitted;
+
+ if (capset(&header, payload) < 0)
+ err(EXIT_FAILURE, _("capset failed"));
+
+ effective = ((uint64_t)payload[1].effective << 32) | (uint64_t)payload[0].effective;
+
+ for (cap = 0; cap < (sizeof(effective) * 8); cap++) {
+ /* This is the same check as cap_valid(), but using
+ * the runtime value for the last valid cap. */
+ if (cap > (uint64_t) cap_last_cap())
+ continue;
+
+ if ((effective & (1 << cap))
+ && prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, cap, 0, 0) < 0)
+ err(EXIT_FAILURE, _("prctl(PR_CAP_AMBIENT) failed"));
+ }
+ }
+
+ if (optind < argc) {
+ execvp(argv[optind], argv + optind);
+ errexec(argv[optind]);
+ }
+ exec_shell();
+}
generated by cgit v1.2.3 (git 2.39.1) at 2025-01-10 10:39:34 +0000