2 * Copyright (C) 2015 John Crispin <blogic@openwrt.org>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU Lesser General Public License version 2.1
6 * as published by the Free Software Foundation
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
15 #include <sys/mount.h>
16 #include <sys/prctl.h>
28 #include <linux/limits.h>
31 #include "capabilities.h"
34 #include <libubox/list.h>
35 #include <libubox/uloop.h>
37 #define STACK_SIZE (1024 * 1024)
38 #define OPT_ARGS "P:S:C:n:r:w:d:psulo"
53 struct list_head list;
60 static LIST_HEAD(extras);
62 extern int pivot_root(const char *new_root, const char *put_old);
66 static char child_stack[STACK_SIZE];
68 static int mkdir_p(char *dir, mode_t mask)
70 char *l = strrchr(dir, '/');
78 if (mkdir_p(dir, mask))
83 ret = mkdir(dir, mask);
84 if (ret && errno == EEXIST)
88 ERROR("mkdir failed on %s: %s\n", dir, strerror(errno));
93 static int mount_bind(const char *root, const char *path, const char *name, int readonly, int error)
100 snprintf(old, sizeof(old), "%s/%s", path, name);
101 snprintf(new, sizeof(new), "%s%s", root, path);
105 snprintf(new, sizeof(new), "%s%s/%s", root, path, name);
108 ERROR("%s does not exist\n", old);
112 if (S_ISDIR(s.st_mode)) {
115 fd = creat(new, 0644);
117 ERROR("failed to create %s: %s\n", new, strerror(errno));
123 if (mount(old, new, NULL, MS_BIND, NULL)) {
124 ERROR("failed to mount -B %s %s: %s\n", old, new, strerror(errno));
128 if (readonly && mount(NULL, new, NULL, MS_BIND | MS_REMOUNT | MS_RDONLY, NULL)) {
129 ERROR("failed to remount ro %s: %s\n", new, strerror(errno));
133 DEBUG("mount -B %s %s\n", old, new);
138 static int build_jail_fs(void)
143 if (mount("tmpfs", opts.path, "tmpfs", MS_NOATIME, "mode=0755")) {
144 ERROR("tmpfs mount failed %s\n", strerror(errno));
148 if (chdir(opts.path)) {
149 ERROR("failed to chdir() in the jail root\n");
153 init_library_search();
155 if (elf_load_deps(*opts.jail_argv)) {
156 ERROR("failed to load dependencies\n");
160 if (opts.seccomp && elf_load_deps("libpreload-seccomp.so")) {
161 ERROR("failed to load libpreload-seccomp.so\n");
165 avl_for_each_element(&libraries, l, avl)
166 if (mount_bind(opts.path, l->path, l->name, 1, -1))
169 list_for_each_entry(m, &extras, list)
170 if (mount_bind(opts.path, m->path, m->name, m->readonly, 0))
174 if (asprintf(&mpoint, "%s/old", opts.path) < 0) {
175 ERROR("failed to alloc pivot path: %s\n", strerror(errno));
178 mkdir_p(mpoint, 0755);
179 if (pivot_root(opts.path, mpoint) == -1) {
180 ERROR("pivot_root failed:%s\n", strerror(errno));
185 umount2("/old", MNT_DETACH);
188 mkdir("/proc", 0755);
189 mount("proc", "/proc", "proc", MS_NOATIME | MS_NODEV | MS_NOEXEC | MS_NOSUID, 0);
193 mount("sysfs", "/sys", "sysfs", MS_NOATIME | MS_NODEV | MS_NOEXEC | MS_NOSUID, 0);
196 mount(NULL, "/", NULL, MS_RDONLY | MS_REMOUNT, 0);
202 static char** build_envp(const char *seccomp)
204 static char *envp[MAX_ENVP];
205 static char preload_var[PATH_MAX];
206 static char seccomp_var[PATH_MAX];
207 static char debug_var[] = "LD_DEBUG=all";
208 const char *preload_lib = find_lib("libpreload-seccomp.so");
211 if (seccomp && !preload_lib) {
212 ERROR("failed to add preload-lib to env\n");
216 snprintf(seccomp_var, sizeof(seccomp_var), "SECCOMP_FILE=%s", seccomp);
217 envp[count++] = seccomp_var;
218 snprintf(preload_var, sizeof(preload_var), "LD_PRELOAD=%s", preload_lib);
219 envp[count++] = preload_var;
222 envp[count++] = debug_var;
227 static void usage(void)
229 fprintf(stderr, "ujail <options> -- <binary> <params ...>\n");
230 fprintf(stderr, " -d <num>\tshow debug log (increase num to increase verbosity)\n");
231 fprintf(stderr, " -S <file>\tseccomp filter config\n");
232 fprintf(stderr, " -C <file>\tcapabilities drop config\n");
233 fprintf(stderr, " -n <name>\tthe name of the jail\n");
234 fprintf(stderr, "namespace jail options:\n");
235 fprintf(stderr, " -P <path>\tpath where the jail will be staged\n");
236 fprintf(stderr, " -r <file>\treadonly files that should be staged\n");
237 fprintf(stderr, " -w <file>\twriteable files that should be staged\n");
238 fprintf(stderr, " -p\t\tjail has /proc\n");
239 fprintf(stderr, " -s\t\tjail has /sys\n");
240 fprintf(stderr, " -l\t\tjail has /dev/log\n");
241 fprintf(stderr, " -u\t\tjail has a ubus socket\n");
242 fprintf(stderr, " -o\t\tremont jail root (/) read only\n");
243 fprintf(stderr, "\nWarning: by default root inside the jail is the same\n\
244 and he has the same powers as root outside the jail,\n\
245 thus he can escape the jail and/or break stuff.\n\
246 Please use seccomp/capabilities (-S/-C) to restrict his powers\n\n\
247 If you use none of the namespace jail options,\n\
248 ujail will not use namespace/build a jail,\n\
249 and will only drop capabilities/apply seccomp filter.\n\n");
252 static int exec_jail(void)
254 char **envp = build_envp(opts.seccomp);
258 if (opts.capabilities && drop_capabilities(opts.capabilities))
261 INFO("exec-ing %s\n", *opts.jail_argv);
262 execve(*opts.jail_argv, opts.jail_argv, envp);
263 //we get there only if execve fails
264 ERROR("failed to execve %s: %s\n", *opts.jail_argv, strerror(errno));
268 static int spawn_jail(void *_notused)
270 if (opts.name && sethostname(opts.name, strlen(opts.name))) {
271 ERROR("failed to sethostname: %s\n", strerror(errno));
274 if (build_jail_fs()) {
275 ERROR("failed to build jail fs");
282 static int jail_running = 1;
283 static int jail_return_code = 0;
285 static void jail_process_handler(struct uloop_process *c, int ret)
287 if (WIFEXITED(ret)) {
288 jail_return_code = WEXITSTATUS(ret);
289 INFO("jail (%d) exited with exit: %d\n", c->pid, jail_return_code);
291 jail_return_code = WTERMSIG(ret);
292 INFO("jail (%d) exited with signal: %d\n", c->pid, jail_return_code);
298 static struct uloop_process jail_process = {
299 .cb = jail_process_handler,
302 static void add_extra(char *name, int readonly)
307 ERROR("%s is not an absolute path\n", name);
311 f = calloc(1, sizeof(struct extra));
313 f->name = basename(name);
314 f->path = dirname(strdup(name));
315 f->readonly = readonly;
317 list_add_tail(&f->list, &extras);
320 int main(int argc, char **argv)
322 uid_t uid = getuid();
323 char log[] = "/dev/log";
324 char ubus[] = "/var/run/ubus.sock";
325 int ret = EXIT_SUCCESS;
329 ERROR("not root, aborting: %s\n", strerror(errno));
335 while ((ch = getopt(argc, argv, OPT_ARGS)) != -1) {
338 debug = atoi(optarg);
353 opts.seccomp = optarg;
354 add_extra(optarg, 1);
357 opts.capabilities = optarg;
358 add_extra(optarg, 1);
369 add_extra(optarg, 1);
373 add_extra(optarg, 0);
386 //no <binary> param found
387 if (argc - optind < 1) {
391 if (!(opts.namespace||opts.capabilities||opts.seccomp)) {
392 ERROR("Not using namespaces, capabilities or seccomp !!!\n\n");
396 DEBUG("Using namespaces(%d), capabilities(%d), seccomp(%d)\n",
398 opts.capabilities != 0,
401 opts.jail_argv = &argv[optind];
404 prctl(PR_SET_NAME, opts.name, NULL, NULL, NULL);
406 if (opts.namespace && !opts.path && asprintf(&opts.path, "/tmp/%s", basename(*opts.jail_argv)) == -1) {
407 ERROR("failed to asprintf root path: %s\n", strerror(errno));
411 if (opts.namespace && mkdir(opts.path, 0755)) {
412 ERROR("unable to create root path: %s (%s)\n", opts.path, strerror(errno));
417 if (opts.namespace) {
418 jail_process.pid = clone(spawn_jail,
419 child_stack + STACK_SIZE,
420 CLONE_NEWUTS | CLONE_NEWPID | CLONE_NEWNS | CLONE_NEWIPC | SIGCHLD, NULL);
422 jail_process.pid = fork();
425 if (jail_process.pid > 0) {
427 uloop_process_add(&jail_process);
431 DEBUG("uloop interrupted, killing jail process\n");
432 kill(jail_process.pid, SIGTERM);
433 waitpid(jail_process.pid, NULL, 0);
435 } else if (jail_process.pid == 0) {
439 ERROR("failed to clone/fork: %s\n", strerror(errno));
443 if (opts.namespace && rmdir(opts.path)) {
444 ERROR("Unable to remove root path: %s (%s)\n", opts.path, strerror(errno));
451 return jail_return_code;