jail/jail.c

   1 /*
   2  * Copyright (C) 2015 John Crispin <blogic@openwrt.org>
   3  *
   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
   7  *
   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.
  12  */
  13
  14 #define _GNU_SOURCE
  15 #include <sys/mount.h>
  16 #include <sys/prctl.h>
  17 #include <sys/wait.h>
  18 #include <sys/types.h>
  19
  20 #include <stdlib.h>
  21 #include <unistd.h>
  22 #include <errno.h>
  23 #include <pwd.h>
  24 #include <grp.h>
  25 #include <string.h>
  26 #include <sys/stat.h>
  27 #include <fcntl.h>
  28 #include <libgen.h>
  29 #include <sched.h>
  30 #include <linux/limits.h>
  31 #include <signal.h>
  32
  33 #include "capabilities.h"
  34 #include "elf.h"
  35 #include "fs.h"
  36 #include "jail.h"
  37 #include "log.h"
  38
  39 #include <libubox/uloop.h>
  40 #include <libubus.h>
  41
  42 #define STACK_SIZE      (1024 * 1024)
  43 #define OPT_ARGS        "S:C:n:h:r:w:d:psulocU:G:NR:fFO:T:Ey"
  44
  45 static struct {
  46         char *name;
  47         char *hostname;
  48         char **jail_argv;
  49         char *seccomp;
  50         char *capabilities;
  51         char *user;
  52         char *group;
  53         char *extroot;
  54         char *overlaydir;
  55         char *tmpoverlaysize;
  56         int no_new_privs;
  57         int namespace;
  58         int procfs;
  59         int ronly;
  60         int sysfs;
  61         int console;
  62         int pw_uid;
  63         int pw_gid;
  64         int gr_gid;
  65         int require_jail;
  66 } opts;
  67
  68
  69 extern int pivot_root(const char *new_root, const char *put_old);
  70
  71 int debug = 0;
  72
  73 static char child_stack[STACK_SIZE];
  74
  75 int console_fd;
  76
  77 static int mkdir_p(char *dir, mode_t mask)
  78 {
  79         char *l = strrchr(dir, '/');
  80         int ret;
  81
  82         if (!l)
  83                 return 0;
  84
  85         *l = '\0';
  86
  87         if (mkdir_p(dir, mask))
  88                 return -1;
  89
  90         *l = '/';
  91
  92         ret = mkdir(dir, mask);
  93         if (ret && errno == EEXIST)
  94                 return 0;
  95
  96         if (ret)
  97                 ERROR("mkdir(%s, %d) failed: %m\n", dir, mask);
  98
  99         return ret;
 100 }
 101
 102 static int _mount_bind(const char *root, const char *path, const char *target, int readonly, int strict, int error)
 103 {
 104         struct stat s;
 105         char new[PATH_MAX];
 106         int fd;
 107         int remount_flags = MS_BIND | MS_REMOUNT;
 108
 109         if (stat(path, &s)) {
 110                 ERROR("stat(%s) failed: %m\n", path);
 111                 return error;
 112         }
 113
 114         snprintf(new, sizeof(new), "%s%s", root, target?target:path);
 115
 116         if (S_ISDIR(s.st_mode)) {
 117                 mkdir_p(new, 0755);
 118         } else {
 119                 mkdir_p(dirname(new), 0755);
 120                 snprintf(new, sizeof(new), "%s%s", root, target?target:path);
 121                 fd = creat(new, 0644);
 122                 if (fd == -1) {
 123                         ERROR("creat(%s) failed: %m\n", new);
 124                         return -1;
 125                 }
 126                 close(fd);
 127         }
 128
 129         if (mount(path, new, NULL, MS_BIND, NULL)) {
 130                 ERROR("failed to mount -B %s %s: %m\n", path, new);
 131                 return -1;
 132         }
 133
 134         if (readonly)
 135                 remount_flags |= MS_RDONLY;
 136
 137         if (strict)
 138                 remount_flags |= MS_NOEXEC | MS_NOSUID | MS_NODEV;
 139
 140         if ((strict || readonly) && mount(NULL, new, NULL, remount_flags, NULL)) {
 141                 ERROR("failed to remount (%s%s%s) %s: %m\n", readonly?"ro":"rw",
 142                       (readonly && strict)?", ":"", strict?"strict":"", new);
 143                 return -1;
 144         }
 145
 146         DEBUG("mount -B %s %s (%s%s%s)\n", path, new,
 147               readonly?"ro":"rw", (readonly && strict)?", ":"", strict?"strict":"");
 148
 149         return 0;
 150 }
 151
 152 int mount_bind(const char *root, const char *path, int readonly, int error) {
 153         return _mount_bind(root, path, NULL, readonly, 0, error);
 154 }
 155
 156 static int mount_overlay(char *jail_root, char *overlaydir) {
 157         char *upperdir, *workdir, *optsstr;
 158         const char mountoptsformat[] = "lowerdir=%s,upperdir=%s,workdir=%s";
 159         int ret = -1;
 160
 161         if (asprintf(&upperdir, "%s%s", overlaydir, "/upper") < 0)
 162                 goto out;
 163
 164         if (asprintf(&workdir, "%s%s", overlaydir, "/work") < 0)
 165                 goto upper_printf;
 166
 167         if (asprintf(&optsstr, mountoptsformat, jail_root, upperdir, workdir) < 0)
 168                 goto work_printf;
 169
 170         if (mkdir_p(upperdir, 0755) || mkdir_p(workdir, 0755))
 171                 goto opts_printf;
 172
 173         DEBUG("mount -t overlay %s %s (%s)\n", jail_root, jail_root, optsstr);
 174
 175         if (mount(jail_root, jail_root, "overlay", MS_NOATIME, optsstr))
 176                 goto opts_printf;
 177
 178         ret = 0;
 179
 180 opts_printf:
 181         free(optsstr);
 182 work_printf:
 183         free(workdir);
 184 upper_printf:
 185         free(upperdir);
 186 out:
 187         return ret;
 188 }
 189
 190 static void pass_console(int console_fd)
 191 {
 192         struct ubus_context *ctx = ubus_connect(NULL);
 193         static struct blob_buf req;
 194         uint32_t id;
 195
 196         if (!ctx)
 197                 return;
 198
 199         blob_buf_init(&req, 0);
 200         blobmsg_add_string(&req, "name", opts.name);
 201
 202         if (ubus_lookup_id(ctx, "service", &id) ||
 203             ubus_invoke_fd(ctx, id, "console_set", req.head, NULL, NULL, 3000, console_fd))
 204                 INFO("ubus request failed\n");
 205         else
 206                 close(console_fd);
 207
 208         blob_buf_free(&req);
 209         ubus_free(ctx);
 210 }
 211
 212 static int create_dev_console(const char *jail_root)
 213 {
 214         char *console_fname;
 215         char dev_console_path[PATH_MAX];
 216         int slave_console_fd;
 217
 218         /* Open UNIX/98 virtual console */
 219         console_fd = posix_openpt(O_RDWR | O_NOCTTY);
 220         if (console_fd == -1)
 221                 return -1;
 222
 223         console_fname = ptsname(console_fd);
 224         DEBUG("got console fd %d and PTS client name %s\n", console_fd, console_fname);
 225         if (!console_fname)
 226                 goto no_console;
 227
 228         grantpt(console_fd);
 229         unlockpt(console_fd);
 230
 231         /* pass PTY master to procd */
 232         pass_console(console_fd);
 233
 234         /* mount-bind PTY slave to /dev/console in jail */
 235         snprintf(dev_console_path, sizeof(dev_console_path), "%s/dev/console", jail_root);
 236         close(creat(dev_console_path, 0620));
 237
 238         if (mount(console_fname, dev_console_path, NULL, MS_BIND, NULL))
 239                 goto no_console;
 240
 241         /* use PTY slave for stdio */
 242         slave_console_fd = open(console_fname, O_RDWR); /* | O_NOCTTY */
 243         dup2(slave_console_fd, 0);
 244         dup2(slave_console_fd, 1);
 245         dup2(slave_console_fd, 2);
 246         close(slave_console_fd);
 247
 248         INFO("using guest console %s\n", console_fname);
 249
 250         return 0;
 251
 252 no_console:
 253         close(console_fd);
 254         return 1;
 255 }
 256
 257 static int build_jail_fs(void)
 258 {
 259         char jail_root[] = "/tmp/ujail-XXXXXX";
 260         char tmpovdir[] = "/tmp/ujail-overlay-XXXXXX";
 261         char tmpdevdir[] = "/tmp/ujail-XXXXXX/dev";
 262         char tmpdevptsdir[] = "/tmp/ujail-XXXXXX/dev/pts";
 263         char *overlaydir = NULL;
 264
 265         if (mkdtemp(jail_root) == NULL) {
 266                 ERROR("mkdtemp(%s) failed: %m\n", jail_root);
 267                 return -1;
 268         }
 269
 270         /* oldroot can't be MS_SHARED else pivot_root() fails */
 271         if (mount("none", "/", NULL, MS_REC|MS_PRIVATE, NULL)) {
 272                 ERROR("private mount failed %m\n");
 273                 return -1;
 274         }
 275
 276         if (opts.extroot) {
 277                 if (mount(opts.extroot, jail_root, NULL, MS_BIND, NULL)) {
 278                         ERROR("extroot mount failed %m\n");
 279                         return -1;
 280                 }
 281         } else {
 282                 if (mount("tmpfs", jail_root, "tmpfs", MS_NOATIME, "mode=0755")) {
 283                         ERROR("tmpfs mount failed %m\n");
 284                         return -1;
 285                 }
 286         }
 287
 288         if (opts.tmpoverlaysize) {
 289                 char mountoptsstr[] = "mode=0755,size=XXXXXXXX";
 290
 291                 snprintf(mountoptsstr, sizeof(mountoptsstr),
 292                          "mode=0755,size=%s", opts.tmpoverlaysize);
 293                 if (mkdtemp(tmpovdir) == NULL) {
 294                         ERROR("mkdtemp(%s) failed: %m\n", jail_root);
 295                         return -1;
 296                 }
 297                 if (mount("tmpfs", tmpovdir, "tmpfs", MS_NOATIME,
 298                           mountoptsstr)) {
 299                         ERROR("failed to mount tmpfs for overlay (size=%s)\n", opts.tmpoverlaysize);
 300                         return -1;
 301                 }
 302                 overlaydir = tmpovdir;
 303         }
 304
 305         if (opts.overlaydir)
 306                 overlaydir = opts.overlaydir;
 307
 308         if (overlaydir)
 309                 mount_overlay(jail_root, overlaydir);
 310
 311         if (chdir(jail_root)) {
 312                 ERROR("chdir(%s) (jail_root) failed: %m\n", jail_root);
 313                 return -1;
 314         }
 315
 316         snprintf(tmpdevdir, sizeof(tmpdevdir), "%s/dev", jail_root);
 317         mkdir_p(tmpdevdir, 0755);
 318         if (mount(NULL, tmpdevdir, "tmpfs", MS_NOATIME | MS_NOEXEC | MS_NOSUID, "size=1M"))
 319                 return -1;
 320
 321         snprintf(tmpdevptsdir, sizeof(tmpdevptsdir), "%s/dev/pts", jail_root);
 322         mkdir_p(tmpdevptsdir, 0755);
 323         if (mount(NULL, tmpdevptsdir, "devpts", MS_NOATIME | MS_NOEXEC | MS_NOSUID, NULL))
 324                 return -1;
 325
 326         if (opts.console)
 327                 create_dev_console(jail_root);
 328
 329         if (mount_all(jail_root)) {
 330                 ERROR("mount_all() failed\n");
 331                 return -1;
 332         }
 333
 334         if (opts.namespace & CLONE_NEWNET) {
 335                 char hostdir[PATH_MAX], jailetc[PATH_MAX], jaillink[PATH_MAX];
 336
 337                 snprintf(hostdir, PATH_MAX, "/tmp/resolv.conf-%s.d", opts.name);
 338                 mkdir_p(hostdir, 0755);
 339                 _mount_bind(jail_root, hostdir, "/tmp/resolv.conf.d", 1, 1, -1);
 340                 snprintf(jailetc, PATH_MAX, "%s/etc", jail_root);
 341                 mkdir_p(jailetc, 0755);
 342                 snprintf(jaillink, PATH_MAX, "%s/etc/resolv.conf", jail_root);
 343                 if (overlaydir)
 344                         unlink(jaillink);
 345                 symlink("../tmp/resolv.conf.d/resolv.conf.auto", jaillink);
 346         }
 347
 348         char dirbuf[sizeof(jail_root) + 4];
 349         snprintf(dirbuf, sizeof(dirbuf), "%s/old", jail_root);
 350         mkdir(dirbuf, 0755);
 351
 352         if (pivot_root(jail_root, dirbuf) == -1) {
 353                 ERROR("pivot_root(%s, %s) failed: %m\n", jail_root, dirbuf);
 354                 return -1;
 355         }
 356         if (chdir("/")) {
 357                 ERROR("chdir(/) (after pivot_root) failed: %m\n");
 358                 return -1;
 359         }
 360
 361         snprintf(dirbuf, sizeof(dirbuf), "/old%s", jail_root);
 362         umount2(dirbuf, MNT_DETACH);
 363         rmdir(dirbuf);
 364         if (opts.tmpoverlaysize) {
 365                 char tmpdirbuf[sizeof(tmpovdir) + 4];
 366                 snprintf(tmpdirbuf, sizeof(tmpdirbuf), "/old%s", tmpovdir);
 367                 umount2(tmpdirbuf, MNT_DETACH);
 368                 rmdir(tmpdirbuf);
 369         }
 370
 371         umount2("/old", MNT_DETACH);
 372         rmdir("/old");
 373
 374         if (opts.procfs) {
 375                 mkdir("/proc", 0755);
 376                 mount("proc", "/proc", "proc", MS_NOATIME | MS_NODEV | MS_NOEXEC | MS_NOSUID, 0);
 377                 /*
 378                  * make /proc/sys read-only while keeping read-write to
 379                  * /proc/sys/net if CLONE_NEWNET is set.
 380                  */
 381                 if (opts.namespace & CLONE_NEWNET)
 382                         mount("/proc/sys/net", "/proc/self/net", NULL, MS_BIND, 0);
 383
 384                 mount("/proc/sys", "/proc/sys", NULL, MS_BIND, 0);
 385                 mount(NULL, "/proc/sys", NULL, MS_REMOUNT | MS_RDONLY, 0);
 386                 mount(NULL, "/proc", NULL, MS_REMOUNT, 0);
 387
 388                 if (opts.namespace & CLONE_NEWNET)
 389                         mount("/proc/self/net", "/proc/sys/net", NULL, MS_MOVE, 0);
 390         }
 391         if (opts.sysfs) {
 392                 mkdir("/sys", 0755);
 393                 mount("sysfs", "/sys", "sysfs", MS_NOATIME | MS_NODEV | MS_NOEXEC | MS_NOSUID | MS_RDONLY, 0);
 394         }
 395         if (opts.ronly)
 396                 mount(NULL, "/", NULL, MS_RDONLY | MS_REMOUNT, 0);
 397
 398         return 0;
 399 }
 400
 401 static int write_uid_gid_map(pid_t child_pid, bool gidmap, int id)
 402 {
 403         int map_file;
 404         char map_path[64];
 405         const char *map_format = "%d %d %d\n";
 406         if (snprintf(map_path, sizeof(map_path), "/proc/%d/%s",
 407                 child_pid, gidmap?"gid_map":"uid_map") < 0)
 408                 return -1;
 409
 410         if ((map_file = open(map_path, O_WRONLY)) == -1)
 411                 return -1;
 412
 413         if (dprintf(map_file, map_format, 0, id, 1) == -1) {
 414                 close(map_file);
 415                 return -1;
 416         }
 417
 418         close(map_file);
 419         return 0;
 420 }
 421
 422 static int write_setgroups(pid_t child_pid, bool allow)
 423 {
 424         int setgroups_file;
 425         char setgroups_path[64];
 426
 427         if (snprintf(setgroups_path, sizeof(setgroups_path), "/proc/%d/setgroups",
 428                 child_pid) < 0) {
 429                 return -1;
 430         }
 431
 432         if ((setgroups_file = open(setgroups_path, O_WRONLY)) == -1) {
 433                 return -1;
 434         }
 435
 436         if (dprintf(setgroups_file, allow?"allow":"deny") == -1) {
 437                 close(setgroups_file);
 438                 return -1;
 439         }
 440
 441         close(setgroups_file);
 442         return 0;
 443 }
 444
 445 static void get_jail_user(int *user, int *user_gid, int *gr_gid)
 446 {
 447         struct passwd *p = NULL;
 448         struct group *g = NULL;
 449
 450         if (opts.user) {
 451                 p = getpwnam(opts.user);
 452                 if (!p) {
 453                         ERROR("failed to get uid/gid for user %s: %d (%s)\n",
 454                               opts.user, errno, strerror(errno));
 455                         exit(EXIT_FAILURE);
 456                 }
 457                 *user = p->pw_uid;
 458                 *user_gid = p->pw_gid;
 459         } else {
 460                 *user = -1;
 461                 *user_gid = -1;
 462         }
 463
 464         if (opts.group) {
 465                 g = getgrnam(opts.group);
 466                 if (!g) {
 467                         ERROR("failed to get gid for group %s: %m\n", opts.group);
 468                         exit(EXIT_FAILURE);
 469                 }
 470                 *gr_gid = g->gr_gid;
 471         } else {
 472                 *gr_gid = -1;
 473         }
 474 };
 475
 476 static void set_jail_user(int pw_uid, int user_gid, int gr_gid)
 477 {
 478         if ((user_gid != -1) && initgroups(opts.user, user_gid)) {
 479                 ERROR("failed to initgroups() for user %s: %m\n", opts.user);
 480                 exit(EXIT_FAILURE);
 481         }
 482
 483         if ((gr_gid != -1) && setregid(gr_gid, gr_gid)) {
 484                 ERROR("failed to set group id %d: %m\n", gr_gid);
 485                 exit(EXIT_FAILURE);
 486         }
 487
 488         if ((pw_uid != -1) && setreuid(pw_uid, pw_uid)) {
 489                 ERROR("failed to set user id %d: %m\n", pw_uid);
 490                 exit(EXIT_FAILURE);
 491         }
 492 }
 493
 494 #define MAX_ENVP        8
 495 static char** build_envp(const char *seccomp)
 496 {
 497         static char *envp[MAX_ENVP];
 498         static char preload_var[PATH_MAX];
 499         static char seccomp_var[PATH_MAX];
 500         static char debug_var[] = "LD_DEBUG=all";
 501         static char container_var[] = "container=ujail";
 502         const char *preload_lib = find_lib("libpreload-seccomp.so");
 503         int count = 0;
 504
 505         if (seccomp && !preload_lib) {
 506                 ERROR("failed to add preload-lib to env\n");
 507                 return NULL;
 508         }
 509         if (seccomp) {
 510                 snprintf(seccomp_var, sizeof(seccomp_var), "SECCOMP_FILE=%s", seccomp);
 511                 envp[count++] = seccomp_var;
 512                 snprintf(preload_var, sizeof(preload_var), "LD_PRELOAD=%s", preload_lib);
 513                 envp[count++] = preload_var;
 514         }
 515
 516         envp[count++] = container_var;
 517
 518         if (debug > 1)
 519                 envp[count++] = debug_var;
 520
 521         return envp;
 522 }
 523
 524 static void usage(void)
 525 {
 526         fprintf(stderr, "ujail <options> -- <binary> <params ...>\n");
 527         fprintf(stderr, "  -d <num>\tshow debug log (increase num to increase verbosity)\n");
 528         fprintf(stderr, "  -S <file>\tseccomp filter config\n");
 529         fprintf(stderr, "  -C <file>\tcapabilities drop config\n");
 530         fprintf(stderr, "  -c\t\tset PR_SET_NO_NEW_PRIVS\n");
 531         fprintf(stderr, "  -n <name>\tthe name of the jail\n");
 532         fprintf(stderr, "namespace jail options:\n");
 533         fprintf(stderr, "  -h <hostname>\tchange the hostname of the jail\n");
 534         fprintf(stderr, "  -N\t\tjail has network namespace\n");
 535         fprintf(stderr, "  -f\t\tjail has user namespace\n");
 536         fprintf(stderr, "  -F\t\tjail has cgroups namespace\n");
 537         fprintf(stderr, "  -r <file>\treadonly files that should be staged\n");
 538         fprintf(stderr, "  -w <file>\twriteable files that should be staged\n");
 539         fprintf(stderr, "  -p\t\tjail has /proc\n");
 540         fprintf(stderr, "  -s\t\tjail has /sys\n");
 541         fprintf(stderr, "  -l\t\tjail has /dev/log\n");
 542         fprintf(stderr, "  -u\t\tjail has a ubus socket\n");
 543         fprintf(stderr, "  -U <name>\tuser to run jailed process\n");
 544         fprintf(stderr, "  -G <name>\tgroup to run jailed process\n");
 545         fprintf(stderr, "  -o\t\tremont jail root (/) read only\n");
 546         fprintf(stderr, "  -R <dir>\texternal jail rootfs (system container)\n");
 547         fprintf(stderr, "  -O <dir>\tdirectory for r/w overlayfs\n");
 548         fprintf(stderr, "  -T <size>\tuse tmpfs r/w overlayfs with <size>\n");
 549         fprintf(stderr, "  -E\t\tfail if jail cannot be setup\n");
 550         fprintf(stderr, "  -y\t\tprovide jail console\n");
 551         fprintf(stderr, "\nWarning: by default root inside the jail is the same\n\
 552 and he has the same powers as root outside the jail,\n\
 553 thus he can escape the jail and/or break stuff.\n\
 554 Please use seccomp/capabilities (-S/-C) to restrict his powers\n\n\
 555 If you use none of the namespace jail options,\n\
 556 ujail will not use namespace/build a jail,\n\
 557 and will only drop capabilities/apply seccomp filter.\n\n");
 558 }
 559
 560 static int exec_jail(void *pipes_ptr)
 561 {
 562         int *pipes = (int*)pipes_ptr;
 563         char buf[1];
 564         int pw_uid, pw_gid, gr_gid;
 565
 566         close(pipes[0]);
 567         close(pipes[3]);
 568
 569         buf[0] = 'i';
 570         if (write(pipes[1], buf, 1) < 1) {
 571                 ERROR("can't write to parent\n");
 572                 exit(EXIT_FAILURE);
 573         }
 574         if (read(pipes[2], buf, 1) < 1) {
 575                 ERROR("can't read from parent\n");
 576                 exit(EXIT_FAILURE);
 577         }
 578         if (buf[0] != 'O') {
 579                 ERROR("parent had an error, child exiting\n");
 580                 exit(EXIT_FAILURE);
 581         }
 582
 583         close(pipes[1]);
 584         close(pipes[2]);
 585
 586         if (opts.namespace & CLONE_NEWUSER) {
 587                 if (setgid(0) < 0) {
 588                         ERROR("setgid\n");
 589                         exit(EXIT_FAILURE);
 590                 }
 591                 if (setuid(0) < 0) {
 592                         ERROR("setuid\n");
 593                         exit(EXIT_FAILURE);
 594                 }
 595 //              if (setgroups(0, NULL) < 0) {
 596 //                      ERROR("setgroups\n");
 597 //                      exit(EXIT_FAILURE);
 598 //              }
 599         }
 600
 601         if (opts.namespace && opts.hostname && strlen(opts.hostname) > 0
 602                         && sethostname(opts.hostname, strlen(opts.hostname))) {
 603                 ERROR("sethostname(%s) failed: %m\n", opts.hostname);
 604                 exit(EXIT_FAILURE);
 605         }
 606
 607         if ((opts.namespace & CLONE_NEWNS) && build_jail_fs()) {
 608                 ERROR("failed to build jail fs\n");
 609                 exit(EXIT_FAILURE);
 610         }
 611
 612         if (opts.capabilities && drop_capabilities(opts.capabilities))
 613                 exit(EXIT_FAILURE);
 614
 615         if (opts.no_new_privs && prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
 616                 ERROR("prctl(PR_SET_NO_NEW_PRIVS) failed: %m\n");
 617                 exit(EXIT_FAILURE);
 618         }
 619
 620         if (!(opts.namespace & CLONE_NEWUSER)) {
 621                 get_jail_user(&pw_uid, &pw_gid, &gr_gid);
 622                 set_jail_user(pw_uid, pw_gid, gr_gid);
 623         }
 624
 625         char **envp = build_envp(opts.seccomp);
 626         if (!envp)
 627                 exit(EXIT_FAILURE);
 628
 629         INFO("exec-ing %s\n", *opts.jail_argv);
 630         execve(*opts.jail_argv, opts.jail_argv, envp);
 631         /* we get there only if execve fails */
 632         ERROR("failed to execve %s: %m\n", *opts.jail_argv);
 633         exit(EXIT_FAILURE);
 634 }
 635
 636 static int jail_running = 1;
 637 static int jail_return_code = 0;
 638
 639 static void jail_process_timeout_cb(struct uloop_timeout *t);
 640 static struct uloop_timeout jail_process_timeout = {
 641         .cb = jail_process_timeout_cb,
 642 };
 643
 644 static void jail_process_handler(struct uloop_process *c, int ret)
 645 {
 646         uloop_timeout_cancel(&jail_process_timeout);
 647         if (WIFEXITED(ret)) {
 648                 jail_return_code = WEXITSTATUS(ret);
 649                 INFO("jail (%d) exited with exit: %d\n", c->pid, jail_return_code);
 650         } else {
 651                 jail_return_code = WTERMSIG(ret);
 652                 INFO("jail (%d) exited with signal: %d\n", c->pid, jail_return_code);
 653         }
 654         jail_running = 0;
 655         uloop_end();
 656 }
 657
 658 static struct uloop_process jail_process = {
 659         .cb = jail_process_handler,
 660 };
 661
 662 static void jail_process_timeout_cb(struct uloop_timeout *t)
 663 {
 664         DEBUG("jail process failed to stop, sending SIGKILL\n");
 665         kill(jail_process.pid, SIGKILL);
 666 }
 667
 668 static void jail_handle_signal(int signo)
 669 {
 670         DEBUG("forwarding signal %d to the jailed process\n", signo);
 671         kill(jail_process.pid, signo);
 672 }
 673
 674 static int netns_open_pid(const pid_t target_ns)
 675 {
 676         char pid_net_path[PATH_MAX];
 677
 678         snprintf(pid_net_path, sizeof(pid_net_path), "/proc/%u/ns/net", target_ns);
 679
 680         return open(pid_net_path, O_RDONLY);
 681 }
 682
 683 static void netns_updown(pid_t pid, bool start)
 684 {
 685         struct ubus_context *ctx = ubus_connect(NULL);
 686         static struct blob_buf req;
 687         uint32_t id;
 688
 689         if (!ctx)
 690                 return;
 691
 692         blob_buf_init(&req, 0);
 693         blobmsg_add_string(&req, "jail", opts.name);
 694         blobmsg_add_u32(&req, "pid", pid);
 695         blobmsg_add_u8(&req, "start", start);
 696
 697         if (ubus_lookup_id(ctx, "network", &id) ||
 698             ubus_invoke(ctx, id, "netns_updown", req.head, NULL, NULL, 3000))
 699                 INFO("ubus request failed\n");
 700
 701         blob_buf_free(&req);
 702         ubus_free(ctx);
 703 }
 704
 705 int main(int argc, char **argv)
 706 {
 707         sigset_t sigmask;
 708         uid_t uid = getuid();
 709         char log[] = "/dev/log";
 710         char ubus[] = "/var/run/ubus.sock";
 711         int ch, i;
 712         int pipes[4];
 713         char sig_buf[1];
 714         int netns_fd;
 715
 716         if (uid) {
 717                 ERROR("not root, aborting: %m\n");
 718                 return EXIT_FAILURE;
 719         }
 720
 721         umask(022);
 722         mount_list_init();
 723         init_library_search();
 724
 725         while ((ch = getopt(argc, argv, OPT_ARGS)) != -1) {
 726                 switch (ch) {
 727                 case 'd':
 728                         debug = atoi(optarg);
 729                         break;
 730                 case 'p':
 731                         opts.namespace |= CLONE_NEWNS;
 732                         opts.procfs = 1;
 733                         break;
 734                 case 'o':
 735                         opts.namespace |= CLONE_NEWNS;
 736                         opts.ronly = 1;
 737                         break;
 738                 case 'f':
 739                         opts.namespace |= CLONE_NEWUSER;
 740                         break;
 741                 case 'F':
 742                         opts.namespace |= CLONE_NEWCGROUP;
 743                         break;
 744                 case 'R':
 745                         opts.extroot = optarg;
 746                         break;
 747                 case 's':
 748                         opts.namespace |= CLONE_NEWNS;
 749                         opts.sysfs = 1;
 750                         break;
 751                 case 'S':
 752                         opts.seccomp = optarg;
 753                         add_mount(optarg, 1, -1);
 754                         break;
 755                 case 'C':
 756                         opts.capabilities = optarg;
 757                         break;
 758                 case 'c':
 759                         opts.no_new_privs = 1;
 760                         break;
 761                 case 'n':
 762                         opts.name = optarg;
 763                         break;
 764                 case 'N':
 765                         opts.namespace |= CLONE_NEWNET;
 766                         break;
 767                 case 'h':
 768                         opts.namespace |= CLONE_NEWUTS;
 769                         opts.hostname = optarg;
 770                         break;
 771                 case 'r':
 772                         opts.namespace |= CLONE_NEWNS;
 773                         add_path_and_deps(optarg, 1, 0, 0);
 774                         break;
 775                 case 'w':
 776                         opts.namespace |= CLONE_NEWNS;
 777                         add_path_and_deps(optarg, 0, 0, 0);
 778                         break;
 779                 case 'u':
 780                         opts.namespace |= CLONE_NEWNS;
 781                         add_mount(ubus, 0, -1);
 782                         break;
 783                 case 'l':
 784                         opts.namespace |= CLONE_NEWNS;
 785                         add_mount(log, 0, -1);
 786                         break;
 787                 case 'U':
 788                         opts.user = optarg;
 789                         break;
 790                 case 'G':
 791                         opts.group = optarg;
 792                         break;
 793                 case 'O':
 794                         opts.overlaydir = optarg;
 795                         break;
 796                 case 'T':
 797                         opts.tmpoverlaysize = optarg;
 798                         break;
 799                 case 'E':
 800                         opts.require_jail = 1;
 801                         break;
 802                 case 'y':
 803                         opts.console = 1;
 804                         break;
 805                 }
 806         }
 807
 808         if (opts.namespace)
 809                 opts.namespace |= CLONE_NEWIPC | CLONE_NEWPID;
 810
 811         if (opts.tmpoverlaysize && strlen(opts.tmpoverlaysize) > 8) {
 812                 ERROR("size parameter too long: \"%s\"\n", opts.tmpoverlaysize);
 813                 return -1;
 814         }
 815
 816         /* no <binary> param found */
 817         if (argc - optind < 1) {
 818                 usage();
 819                 return EXIT_FAILURE;
 820         }
 821         if (!(opts.namespace||opts.capabilities||opts.seccomp)) {
 822                 ERROR("Not using namespaces, capabilities or seccomp !!!\n\n");
 823                 usage();
 824                 return EXIT_FAILURE;
 825         }
 826         DEBUG("Using namespaces(0x%08x), capabilities(%d), seccomp(%d)\n",
 827                 opts.namespace,
 828                 opts.capabilities != 0,
 829                 opts.seccomp != 0);
 830
 831         opts.jail_argv = &argv[optind];
 832
 833         get_jail_user(&opts.pw_uid, &opts.pw_gid, &opts.gr_gid);
 834
 835         if (!opts.extroot) {
 836                 if (opts.namespace && add_path_and_deps(*opts.jail_argv, 1, -1, 0)) {
 837                         ERROR("failed to load dependencies\n");
 838                         return -1;
 839                 }
 840         }
 841
 842         if (opts.namespace && opts.seccomp && add_path_and_deps("libpreload-seccomp.so", 1, -1, 1)) {
 843                 ERROR("failed to load libpreload-seccomp.so\n");
 844                 opts.seccomp = 0;
 845                 if (opts.require_jail)
 846                         return -1;
 847         }
 848
 849         if (opts.name)
 850                 prctl(PR_SET_NAME, opts.name, NULL, NULL, NULL);
 851
 852         uloop_init();
 853
 854         sigfillset(&sigmask);
 855         for (i = 0; i < _NSIG; i++) {
 856                 struct sigaction s = { 0 };
 857
 858                 if (!sigismember(&sigmask, i))
 859                         continue;
 860                 if ((i == SIGCHLD) || (i == SIGPIPE) || (i == SIGSEGV))
 861                         continue;
 862
 863                 s.sa_handler = jail_handle_signal;
 864                 sigaction(i, &s, NULL);
 865         }
 866
 867         if (opts.namespace) {
 868                 if (opts.namespace & CLONE_NEWNS) {
 869                         add_mount("/dev/full", 0, -1);
 870                         add_mount("/dev/null", 0, -1);
 871                         add_mount("/dev/random", 0, -1);
 872                         add_mount("/dev/urandom", 0, -1);
 873                         add_mount("/dev/zero", 0, -1);
 874                         add_mount("/dev/ptmx", 0, -1);
 875                         add_mount("/dev/tty", 0, -1);
 876
 877                         if (!opts.extroot && (opts.user || opts.group)) {
 878                                 add_mount("/etc/passwd", 0, -1);
 879                                 add_mount("/etc/group", 0, -1);
 880                         }
 881
 882 #if defined(__GLIBC__)
 883                         if (!opts.extroot)
 884                                 add_mount("/etc/nsswitch.conf", 0, -1);
 885 #endif
 886
 887                         if (!(opts.namespace & CLONE_NEWNET)) {
 888                                 add_mount("/etc/resolv.conf", 0, -1);
 889                         }
 890                 }
 891
 892                 if (pipe(&pipes[0]) < 0 || pipe(&pipes[2]) < 0)
 893                         return -1;
 894
 895                 jail_process.pid = clone(exec_jail, child_stack + STACK_SIZE, SIGCHLD | opts.namespace, &pipes);
 896         } else {
 897                 jail_process.pid = fork();
 898         }
 899
 900         if (jail_process.pid > 0) {
 901                 seteuid(0);
 902                 /* parent process */
 903                 close(pipes[1]);
 904                 close(pipes[2]);
 905                 if (read(pipes[0], sig_buf, 1) < 1) {
 906                         ERROR("can't read from child\n");
 907                         return -1;
 908                 }
 909                 close(pipes[0]);
 910                 if (opts.namespace & CLONE_NEWUSER) {
 911                         bool has_gr = (opts.gr_gid != -1);
 912                         if (write_setgroups(jail_process.pid, false)) {
 913                                 ERROR("can't write setgroups\n");
 914                                 return -1;
 915                         }
 916                         if (opts.pw_uid != -1) {
 917                                 write_uid_gid_map(jail_process.pid, 0, opts.pw_uid);
 918                                 write_uid_gid_map(jail_process.pid, 1, has_gr?opts.gr_gid:opts.pw_gid);
 919                         } else {
 920                                 write_uid_gid_map(jail_process.pid, 0, 65534);
 921                                 write_uid_gid_map(jail_process.pid, 1, has_gr?opts.gr_gid:65534);
 922                         }
 923                 }
 924
 925                 if (opts.namespace & CLONE_NEWNET) {
 926                         if (!opts.name) {
 927                                 ERROR("netns needs a named jail\n");
 928                                 return -1;
 929                         }
 930                         netns_fd = netns_open_pid(jail_process.pid);
 931                         netns_updown(jail_process.pid, true);
 932                 }
 933
 934                 sig_buf[0] = 'O';
 935                 if (write(pipes[3], sig_buf, 1) < 0) {
 936                         ERROR("can't write to child\n");
 937                         return -1;
 938                 }
 939                 close(pipes[3]);
 940                 uloop_process_add(&jail_process);
 941                 uloop_run();
 942                 if (jail_running) {
 943                         DEBUG("uloop interrupted, killing jail process\n");
 944                         kill(jail_process.pid, SIGTERM);
 945                         uloop_timeout_set(&jail_process_timeout, 1000);
 946                         uloop_run();
 947                 }
 948                 uloop_done();
 949                 if (opts.namespace & CLONE_NEWNET) {
 950                         setns(netns_fd, CLONE_NEWNET);
 951                         netns_updown(getpid(), false);
 952                         close(netns_fd);
 953                 }
 954                 return jail_return_code;
 955         } else if (jail_process.pid == 0) {
 956                 /* fork child process */
 957                 return exec_jail(NULL);
 958         } else {
 959                 ERROR("failed to clone/fork: %m\n");
 960                 return EXIT_FAILURE;
 961         }
 962 }