631 lines
17 KiB
C
631 lines
17 KiB
C
/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#include <dlfcn.h>
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#include <getopt.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "libminijail.h"
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#include "libsyscalls.h"
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#include "elfparse.h"
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#include "util.h"
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#define IDMAP_LEN 32U
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static void set_user(struct minijail *j, const char *arg)
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{
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char *end = NULL;
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int uid = strtod(arg, &end);
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if (!*end && *arg) {
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minijail_change_uid(j, uid);
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return;
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}
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if (minijail_change_user(j, arg)) {
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fprintf(stderr, "Bad user: '%s'\n", arg);
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exit(1);
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}
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}
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static void set_group(struct minijail *j, const char *arg)
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{
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char *end = NULL;
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int gid = strtod(arg, &end);
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if (!*end && *arg) {
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minijail_change_gid(j, gid);
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return;
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}
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if (minijail_change_group(j, arg)) {
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fprintf(stderr, "Bad group: '%s'\n", arg);
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exit(1);
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}
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}
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static void skip_securebits(struct minijail *j, const char *arg)
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{
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uint64_t securebits_skip_mask;
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char *end = NULL;
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securebits_skip_mask = strtoull(arg, &end, 16);
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if (*end) {
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fprintf(stderr, "Invalid securebit mask: '%s'\n", arg);
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exit(1);
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}
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minijail_skip_setting_securebits(j, securebits_skip_mask);
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}
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static void use_caps(struct minijail *j, const char *arg)
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{
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uint64_t caps;
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char *end = NULL;
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caps = strtoull(arg, &end, 16);
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if (*end) {
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fprintf(stderr, "Invalid cap set: '%s'\n", arg);
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exit(1);
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}
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minijail_use_caps(j, caps);
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}
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static void add_binding(struct minijail *j, char *arg)
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{
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char *src = strtok(arg, ",");
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char *dest = strtok(NULL, ",");
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char *flags = strtok(NULL, ",");
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if (!src || !dest) {
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fprintf(stderr, "Bad binding: %s %s\n", src, dest);
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exit(1);
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}
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if (minijail_bind(j, src, dest, flags ? atoi(flags) : 0)) {
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fprintf(stderr, "minijail_bind failed.\n");
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exit(1);
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}
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}
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static void add_rlimit(struct minijail *j, char *arg)
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{
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char *type = strtok(arg, ",");
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char *cur = strtok(NULL, ",");
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char *max = strtok(NULL, ",");
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if (!type || !cur || !max) {
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fprintf(stderr, "Bad rlimit '%s'.\n", arg);
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exit(1);
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}
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if (minijail_rlimit(j, atoi(type), atoi(cur), atoi(max))) {
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fprintf(stderr, "minijail_rlimit '%s,%s,%s' failed.\n",
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type, cur, max);
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exit(1);
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}
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}
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static void add_mount(struct minijail *j, char *arg)
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{
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char *src = strtok(arg, ",");
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char *dest = strtok(NULL, ",");
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char *type = strtok(NULL, ",");
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char *flags = strtok(NULL, ",");
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char *data = strtok(NULL, ",");
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if (!src || !dest || !type) {
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fprintf(stderr, "Bad mount: %s %s %s\n", src, dest, type);
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exit(1);
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}
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if (minijail_mount_with_data(j, src, dest, type,
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flags ? strtoul(flags, NULL, 16) : 0,
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data)) {
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fprintf(stderr, "minijail_mount failed.\n");
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exit(1);
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}
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}
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static char *build_idmap(id_t id, id_t lowerid)
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{
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int ret;
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char *idmap = malloc(IDMAP_LEN);
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ret = snprintf(idmap, IDMAP_LEN, "%d %d 1", id, lowerid);
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if (ret < 0 || (size_t)ret >= IDMAP_LEN) {
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free(idmap);
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fprintf(stderr, "Could not build id map.\n");
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exit(1);
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}
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return idmap;
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}
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static void usage(const char *progn)
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{
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size_t i;
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/* clang-format off */
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printf("Usage: %s [-GhHiIKlLnNprRstUvyYz]\n"
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" [-a <table>]\n"
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" [-b <src>,<dest>[,<writeable>]] [-k <src>,<dest>,<type>[,<flags>][,<data>]]\n"
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" [-c <caps>] [-C <dir>] [-P <dir>] [-e[file]] [-f <file>] [-g <group>]\n"
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" [-m[<uid> <loweruid> <count>]*] [-M[<gid> <lowergid> <count>]*]\n"
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" [-R <type,cur,max>] [-S <file>] [-t[size]] [-T <type>] [-u <user>] [-V <file>]\n"
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" <program> [args...]\n"
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" -a <table>: Use alternate syscall table <table>.\n"
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" -b: Bind <src> to <dest> in chroot.\n"
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" Multiple instances allowed.\n"
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" -B <mask> Skip setting securebits in <mask> when restricting capabilities (-c).\n"
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" By default, SECURE_NOROOT, SECURE_NO_SETUID_FIXUP, and \n"
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" SECURE_KEEP_CAPS (together with their respective locks) are set.\n"
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" -k: Mount <src> at <dest> in chroot.\n"
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" <flags> and <data> can be specified as in mount(2).\n"
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" Multiple instances allowed.\n"
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" -c <caps>: Restrict caps to <caps>.\n"
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" -C <dir>: chroot(2) to <dir>.\n"
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" Not compatible with -P.\n"
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" -P <dir>: pivot_root(2) to <dir> (implies -v).\n"
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" Not compatible with -C.\n"
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" -e[file]: Enter new network namespace, or existing one if |file| is provided.\n"
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" -f <file>: Write the pid of the jailed process to <file>.\n"
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" -g <group>: Change gid to <group>.\n"
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" -G: Inherit supplementary groups from uid.\n"
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" Not compatible with -y.\n"
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" -y: Keep uid's supplementary groups.\n"
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" Not compatible with -G.\n"
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" -h: Help (this message).\n"
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" -H: Seccomp filter help message.\n"
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" -i: Exit immediately after fork (do not act as init).\n"
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" -I: Run <program> as init (pid 1) inside a new pid namespace (implies -p).\n"
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" -K: Don't mark all existing mounts as MS_PRIVATE.\n"
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" -l: Enter new IPC namespace.\n"
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" -L: Report blocked syscalls to syslog when using seccomp filter.\n"
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" Forces the following syscalls to be allowed:\n"
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" ", progn);
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/* clang-format on */
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for (i = 0; i < log_syscalls_len; i++)
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printf("%s ", log_syscalls[i]);
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/* clang-format off */
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printf("\n"
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" -m[map]: Set the uid map of a user namespace (implies -pU).\n"
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" Same arguments as newuidmap(1), multiple mappings should be separated by ',' (comma).\n"
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" With no mapping, map the current uid to root inside the user namespace.\n"
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" Not compatible with -b without the 'writable' option.\n"
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" -M[map]: Set the gid map of a user namespace (implies -pU).\n"
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" Same arguments as newgidmap(1), multiple mappings should be separated by ',' (comma).\n"
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" With no mapping, map the current gid to root inside the user namespace.\n"
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" Not compatible with -b without the 'writable' option.\n"
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" -n: Set no_new_privs.\n"
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" -N: Enter a new cgroup namespace.\n"
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" -p: Enter new pid namespace (implies -vr).\n"
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" -r: Remount /proc read-only (implies -v).\n"
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" -R: Set rlimits, can be specified multiple times.\n"
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" -s: Use seccomp mode 1 (not the same as -S).\n"
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" -S <file>: Set seccomp filter using <file>.\n"
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" E.g., '-S /usr/share/filters/<prog>.$(uname -m)'.\n"
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" Requires -n when not running as root.\n"
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" -t[size]: Mount tmpfs at /tmp (implies -v).\n"
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" Optional argument specifies size (default \"64M\").\n"
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" -T <type>: Don't access <program> before execve(2), assume <type> ELF binary.\n"
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" <type> must be 'static' or 'dynamic'.\n"
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" -u <user>: Change uid to <user>.\n"
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" -U: Enter new user namespace (implies -p).\n"
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" -v: Enter new mount namespace.\n"
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" -V <file>: Enter specified mount namespace.\n"
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" -w: Create and join a new anonymous session keyring.\n"
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" -Y: Synchronize seccomp filters across thread group.\n"
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" -z: Don't forward signals to jailed process.\n"
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" --ambient: Raise ambient capabilities. Requires -c.\n"
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" --uts[=name]: Enter a new UTS namespace (and set hostname).\n");
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/* clang-format on */
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}
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static void seccomp_filter_usage(const char *progn)
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{
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const struct syscall_entry *entry = syscall_table;
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printf("Usage: %s -S <policy.file> <program> [args...]\n\n"
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"System call names supported:\n",
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progn);
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for (; entry->name && entry->nr >= 0; ++entry)
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printf(" %s [%d]\n", entry->name, entry->nr);
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printf("\nSee minijail0(5) for example policies.\n");
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}
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static int parse_args(struct minijail *j, int argc, char *argv[],
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int *exit_immediately, ElfType *elftype)
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{
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int opt;
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int use_seccomp_filter = 0;
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int forward = 1;
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int binding = 0;
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int chroot = 0, pivot_root = 0;
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int mount_ns = 0, skip_remount = 0;
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int inherit_suppl_gids = 0, keep_suppl_gids = 0;
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int caps = 0, ambient_caps = 0;
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int seccomp = -1;
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const size_t path_max = 4096;
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char *map;
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size_t size;
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const char *filter_path;
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const char *optstring =
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"+u:g:sS:c:C:P:b:B:V:f:m::M::k:a:e::R:T:vrGhHinNplLt::IUKwyYz";
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int longoption_index = 0;
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/* clang-format off */
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const struct option long_options[] = {
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{"ambient", no_argument, 0, 128},
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{"uts", optional_argument, 0, 129},
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{0, 0, 0, 0},
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};
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/* clang-format on */
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while ((opt = getopt_long(argc, argv, optstring, long_options,
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&longoption_index)) != -1) {
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switch (opt) {
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case 'u':
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set_user(j, optarg);
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break;
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case 'g':
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set_group(j, optarg);
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break;
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case 'n':
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minijail_no_new_privs(j);
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break;
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case 's':
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if (seccomp != -1 && seccomp != 1) {
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fprintf(stderr, "Do not use -s & -S together.\n");
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exit(1);
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}
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seccomp = 1;
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minijail_use_seccomp(j);
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break;
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case 'S':
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if (seccomp != -1 && seccomp != 2) {
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fprintf(stderr, "Do not use -s & -S together.\n");
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exit(1);
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}
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seccomp = 2;
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minijail_use_seccomp_filter(j);
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if (strlen(optarg) >= path_max) {
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fprintf(stderr, "Filter path is too long.\n");
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exit(1);
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}
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filter_path = strndup(optarg, path_max);
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if (!filter_path) {
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fprintf(stderr,
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"Could not strndup(3) filter path.\n");
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exit(1);
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}
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use_seccomp_filter = 1;
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break;
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case 'l':
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minijail_namespace_ipc(j);
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break;
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case 'L':
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minijail_log_seccomp_filter_failures(j);
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break;
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case 'b':
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add_binding(j, optarg);
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binding = 1;
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break;
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case 'B':
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skip_securebits(j, optarg);
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break;
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case 'c':
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caps = 1;
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use_caps(j, optarg);
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break;
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case 'C':
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if (pivot_root) {
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fprintf(stderr, "Could not set chroot because "
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"'-P' was specified.\n");
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exit(1);
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}
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if (0 != minijail_enter_chroot(j, optarg)) {
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fprintf(stderr, "Could not set chroot.\n");
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exit(1);
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}
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chroot = 1;
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break;
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case 'k':
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add_mount(j, optarg);
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break;
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case 'K':
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minijail_skip_remount_private(j);
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skip_remount = 1;
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break;
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case 'P':
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if (chroot) {
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fprintf(stderr,
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"Could not set pivot_root because "
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"'-C' was specified.\n");
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exit(1);
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}
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if (0 != minijail_enter_pivot_root(j, optarg)) {
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fprintf(stderr, "Could not set pivot_root.\n");
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exit(1);
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}
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minijail_namespace_vfs(j);
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pivot_root = 1;
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break;
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case 'f':
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if (0 != minijail_write_pid_file(j, optarg)) {
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fprintf(stderr,
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"Could not prepare pid file path.\n");
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exit(1);
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}
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break;
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case 't':
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minijail_namespace_vfs(j);
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size = 64 * 1024 * 1024;
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if (optarg != NULL && 0 != parse_size(&size, optarg)) {
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fprintf(stderr, "Invalid /tmp tmpfs size.\n");
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exit(1);
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}
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minijail_mount_tmp_size(j, size);
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break;
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case 'v':
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minijail_namespace_vfs(j);
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mount_ns = 1;
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break;
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case 'V':
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minijail_namespace_enter_vfs(j, optarg);
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break;
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case 'r':
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minijail_remount_proc_readonly(j);
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break;
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case 'G':
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if (keep_suppl_gids) {
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fprintf(stderr,
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"-y and -G are not compatible.\n");
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exit(1);
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}
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minijail_inherit_usergroups(j);
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inherit_suppl_gids = 1;
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break;
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case 'y':
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if (inherit_suppl_gids) {
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fprintf(stderr,
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"-y and -G are not compatible.\n");
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exit(1);
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}
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minijail_keep_supplementary_gids(j);
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keep_suppl_gids = 1;
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break;
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case 'N':
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minijail_namespace_cgroups(j);
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break;
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case 'p':
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minijail_namespace_pids(j);
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break;
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case 'e':
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if (optarg)
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minijail_namespace_enter_net(j, optarg);
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else
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minijail_namespace_net(j);
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break;
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case 'i':
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*exit_immediately = 1;
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break;
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case 'H':
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seccomp_filter_usage(argv[0]);
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exit(1);
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case 'I':
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minijail_namespace_pids(j);
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minijail_run_as_init(j);
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break;
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case 'U':
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minijail_namespace_user(j);
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minijail_namespace_pids(j);
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break;
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case 'm':
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minijail_namespace_user(j);
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minijail_namespace_pids(j);
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if (optarg) {
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map = strdup(optarg);
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} else {
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/*
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* If no map is passed, map the current uid to
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* root.
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*/
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map = build_idmap(0, getuid());
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}
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if (0 != minijail_uidmap(j, map)) {
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fprintf(stderr, "Could not set uid map.\n");
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exit(1);
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}
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free(map);
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break;
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case 'M':
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minijail_namespace_user(j);
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minijail_namespace_pids(j);
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if (optarg) {
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map = strdup(optarg);
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} else {
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/*
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* If no map is passed, map the current gid to
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* root.
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* This means that we're likely *not* running as
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* root, so we also have to disable
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* setgroups(2) to be able to set the gid map.
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* See
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* http://man7.org/linux/man-pages/man7/user_namespaces.7.html
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*/
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minijail_namespace_user_disable_setgroups(j);
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map = build_idmap(0, getgid());
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}
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if (0 != minijail_gidmap(j, map)) {
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fprintf(stderr, "Could not set gid map.\n");
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exit(1);
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}
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free(map);
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break;
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case 'a':
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if (0 != minijail_use_alt_syscall(j, optarg)) {
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fprintf(stderr,
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"Could not set alt-syscall table.\n");
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exit(1);
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}
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break;
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case 'R':
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add_rlimit(j, optarg);
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break;
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case 'T':
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if (!strcmp(optarg, "static"))
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*elftype = ELFSTATIC;
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else if (!strcmp(optarg, "dynamic"))
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*elftype = ELFDYNAMIC;
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else {
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fprintf(stderr, "ELF type must be 'static' or "
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"'dynamic'.\n");
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exit(1);
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}
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break;
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case 'w':
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minijail_new_session_keyring(j);
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break;
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case 'Y':
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minijail_set_seccomp_filter_tsync(j);
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break;
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|
case 'z':
|
|
forward = 0;
|
|
break;
|
|
/* Long options. */
|
|
case 128: /* Ambient caps. */
|
|
ambient_caps = 1;
|
|
minijail_set_ambient_caps(j);
|
|
break;
|
|
case 129: /* UTS/hostname namespace. */
|
|
minijail_namespace_uts(j);
|
|
if (optarg)
|
|
minijail_namespace_set_hostname(j, optarg);
|
|
break;
|
|
default:
|
|
usage(argv[0]);
|
|
exit(1);
|
|
}
|
|
}
|
|
|
|
/* Can only set ambient caps when using regular caps. */
|
|
if (ambient_caps && !caps) {
|
|
fprintf(stderr, "Can't set ambient capabilities (--ambient) "
|
|
"without actually using capabilities (-c).\n");
|
|
exit(1);
|
|
}
|
|
|
|
/* Set up signal handlers in minijail unless asked not to. */
|
|
if (forward)
|
|
minijail_forward_signals(j);
|
|
|
|
/* Only allow bind mounts when entering a chroot or using pivot_root. */
|
|
if (binding && !(chroot || pivot_root)) {
|
|
fprintf(stderr, "Can't add bind mounts without chroot or"
|
|
" pivot_root.\n");
|
|
exit(1);
|
|
}
|
|
|
|
/*
|
|
* Remounting / as MS_PRIVATE only happens when entering a new mount
|
|
* namespace, so skipping it only applies in that case.
|
|
*/
|
|
if (skip_remount && !mount_ns) {
|
|
fprintf(stderr, "Can't skip marking mounts as MS_PRIVATE"
|
|
" without mount namespaces.\n");
|
|
exit(1);
|
|
}
|
|
|
|
/*
|
|
* We parse seccomp filters here to make sure we've collected all
|
|
* cmdline options.
|
|
*/
|
|
if (use_seccomp_filter) {
|
|
minijail_parse_seccomp_filters(j, filter_path);
|
|
free((void *)filter_path);
|
|
}
|
|
|
|
/*
|
|
* There should be at least one additional unparsed argument: the
|
|
* executable name.
|
|
*/
|
|
if (argc == optind) {
|
|
usage(argv[0]);
|
|
exit(1);
|
|
}
|
|
|
|
if (*elftype == ELFERROR) {
|
|
/*
|
|
* -T was not specified.
|
|
* Get the path to the program adjusted for changing root.
|
|
*/
|
|
char *program_path =
|
|
minijail_get_original_path(j, argv[optind]);
|
|
|
|
/* Check that we can access the target program. */
|
|
if (access(program_path, X_OK)) {
|
|
fprintf(stderr,
|
|
"Target program '%s' is not accessible.\n",
|
|
argv[optind]);
|
|
exit(1);
|
|
}
|
|
|
|
/* Check if target is statically or dynamically linked. */
|
|
*elftype = get_elf_linkage(program_path);
|
|
free(program_path);
|
|
}
|
|
|
|
/*
|
|
* Setting capabilities need either a dynamically-linked binary, or the
|
|
* use of ambient capabilities for them to be able to survive an
|
|
* execve(2).
|
|
*/
|
|
if (caps && *elftype == ELFSTATIC && !ambient_caps) {
|
|
fprintf(stderr, "Can't run statically-linked binaries with "
|
|
"capabilities (-c) without also setting "
|
|
"ambient capabilities. Try passing "
|
|
"--ambient.\n");
|
|
exit(1);
|
|
}
|
|
|
|
return optind;
|
|
}
|
|
|
|
int main(int argc, char *argv[])
|
|
{
|
|
struct minijail *j = minijail_new();
|
|
const char *dl_mesg = NULL;
|
|
int exit_immediately = 0;
|
|
ElfType elftype = ELFERROR;
|
|
int consumed = parse_args(j, argc, argv, &exit_immediately, &elftype);
|
|
argc -= consumed;
|
|
argv += consumed;
|
|
|
|
if (elftype == ELFSTATIC) {
|
|
/*
|
|
* Target binary is statically linked so we cannot use
|
|
* libminijailpreload.so.
|
|
*/
|
|
minijail_run_no_preload(j, argv[0], argv);
|
|
} else if (elftype == ELFDYNAMIC) {
|
|
/*
|
|
* Target binary is dynamically linked so we can
|
|
* inject libminijailpreload.so into it.
|
|
*/
|
|
|
|
/* Check that we can dlopen() libminijailpreload.so. */
|
|
if (!dlopen(PRELOADPATH, RTLD_LAZY | RTLD_LOCAL)) {
|
|
dl_mesg = dlerror();
|
|
fprintf(stderr, "dlopen(): %s\n", dl_mesg);
|
|
return 1;
|
|
}
|
|
minijail_run(j, argv[0], argv);
|
|
} else {
|
|
fprintf(stderr,
|
|
"Target program '%s' is not a valid ELF file.\n",
|
|
argv[0]);
|
|
return 1;
|
|
}
|
|
|
|
if (exit_immediately) {
|
|
info("not running init loop, exiting immediately");
|
|
return 0;
|
|
}
|
|
return minijail_wait(j);
|
|
}
|