1 /*- 2 * ---------------------------------------------------------------------------- 3 * "THE BEER-WARE LICENSE" (Revision 42): 4 * <phk@FreeBSD.ORG> wrote this file. As long as you retain this notice you 5 * can do whatever you want with this stuff. If we meet some day, and you think 6 * this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp 7 * ---------------------------------------------------------------------------- 8 */ 9 10 #include <sys/cdefs.h> 11 __FBSDID("$FreeBSD$"); 12 13 #include "opt_mac.h" 14 15 #include <sys/param.h> 16 #include <sys/types.h> 17 #include <sys/kernel.h> 18 #include <sys/systm.h> 19 #include <sys/errno.h> 20 #include <sys/sysproto.h> 21 #include <sys/mac.h> 22 #include <sys/malloc.h> 23 #include <sys/proc.h> 24 #include <sys/taskqueue.h> 25 #include <sys/jail.h> 26 #include <sys/lock.h> 27 #include <sys/mutex.h> 28 #include <sys/namei.h> 29 #include <sys/mount.h> 30 #include <sys/queue.h> 31 #include <sys/socket.h> 32 #include <sys/syscallsubr.h> 33 #include <sys/sysctl.h> 34 #include <sys/vnode.h> 35 #include <net/if.h> 36 #include <netinet/in.h> 37 38 MALLOC_DEFINE(M_PRISON, "prison", "Prison structures"); 39 40 SYSCTL_DECL(_security); 41 SYSCTL_NODE(_security, OID_AUTO, jail, CTLFLAG_RW, 0, 42 "Jail rules"); 43 44 int jail_set_hostname_allowed = 1; 45 SYSCTL_INT(_security_jail, OID_AUTO, set_hostname_allowed, CTLFLAG_RW, 46 &jail_set_hostname_allowed, 0, 47 "Processes in jail can set their hostnames"); 48 49 int jail_socket_unixiproute_only = 1; 50 SYSCTL_INT(_security_jail, OID_AUTO, socket_unixiproute_only, CTLFLAG_RW, 51 &jail_socket_unixiproute_only, 0, 52 "Processes in jail are limited to creating UNIX/IPv4/route sockets only"); 53 54 int jail_sysvipc_allowed = 0; 55 SYSCTL_INT(_security_jail, OID_AUTO, sysvipc_allowed, CTLFLAG_RW, 56 &jail_sysvipc_allowed, 0, 57 "Processes in jail can use System V IPC primitives"); 58 59 static int jail_enforce_statfs = 2; 60 SYSCTL_INT(_security_jail, OID_AUTO, enforce_statfs, CTLFLAG_RW, 61 &jail_enforce_statfs, 0, 62 "Processes in jail cannot see all mounted file systems"); 63 64 int jail_allow_raw_sockets = 0; 65 SYSCTL_INT(_security_jail, OID_AUTO, allow_raw_sockets, CTLFLAG_RW, 66 &jail_allow_raw_sockets, 0, 67 "Prison root can create raw sockets"); 68 69 int jail_chflags_allowed = 0; 70 SYSCTL_INT(_security_jail, OID_AUTO, chflags_allowed, CTLFLAG_RW, 71 &jail_chflags_allowed, 0, 72 "Processes in jail can alter system file flags"); 73 74 /* allprison, lastprid, and prisoncount are protected by allprison_mtx. */ 75 struct prisonlist allprison; 76 struct mtx allprison_mtx; 77 int lastprid = 0; 78 int prisoncount = 0; 79 80 static void init_prison(void *); 81 static void prison_complete(void *context, int pending); 82 static struct prison *prison_find(int); 83 static int sysctl_jail_list(SYSCTL_HANDLER_ARGS); 84 85 static void 86 init_prison(void *data __unused) 87 { 88 89 mtx_init(&allprison_mtx, "allprison", NULL, MTX_DEF); 90 LIST_INIT(&allprison); 91 } 92 93 SYSINIT(prison, SI_SUB_INTRINSIC, SI_ORDER_ANY, init_prison, NULL); 94 95 /* 96 * MPSAFE 97 * 98 * struct jail_args { 99 * struct jail *jail; 100 * }; 101 */ 102 int 103 jail(struct thread *td, struct jail_args *uap) 104 { 105 struct nameidata nd; 106 struct prison *pr, *tpr; 107 struct jail j; 108 struct jail_attach_args jaa; 109 int vfslocked, error, tryprid; 110 111 error = copyin(uap->jail, &j, sizeof(j)); 112 if (error) 113 return (error); 114 if (j.version != 0) 115 return (EINVAL); 116 117 MALLOC(pr, struct prison *, sizeof(*pr), M_PRISON, M_WAITOK | M_ZERO); 118 mtx_init(&pr->pr_mtx, "jail mutex", NULL, MTX_DEF); 119 pr->pr_ref = 1; 120 error = copyinstr(j.path, &pr->pr_path, sizeof(pr->pr_path), 0); 121 if (error) 122 goto e_killmtx; 123 NDINIT(&nd, LOOKUP, MPSAFE | FOLLOW | LOCKLEAF, UIO_SYSSPACE, 124 pr->pr_path, td); 125 error = namei(&nd); 126 if (error) 127 goto e_killmtx; 128 vfslocked = NDHASGIANT(&nd); 129 pr->pr_root = nd.ni_vp; 130 VOP_UNLOCK(nd.ni_vp, 0, td); 131 NDFREE(&nd, NDF_ONLY_PNBUF); 132 VFS_UNLOCK_GIANT(vfslocked); 133 error = copyinstr(j.hostname, &pr->pr_host, sizeof(pr->pr_host), 0); 134 if (error) 135 goto e_dropvnref; 136 pr->pr_ip = j.ip_number; 137 pr->pr_linux = NULL; 138 pr->pr_securelevel = securelevel; 139 140 /* Determine next pr_id and add prison to allprison list. */ 141 mtx_lock(&allprison_mtx); 142 tryprid = lastprid + 1; 143 if (tryprid == JAIL_MAX) 144 tryprid = 1; 145 next: 146 LIST_FOREACH(tpr, &allprison, pr_list) { 147 if (tpr->pr_id == tryprid) { 148 tryprid++; 149 if (tryprid == JAIL_MAX) { 150 mtx_unlock(&allprison_mtx); 151 error = EAGAIN; 152 goto e_dropvnref; 153 } 154 goto next; 155 } 156 } 157 pr->pr_id = jaa.jid = lastprid = tryprid; 158 LIST_INSERT_HEAD(&allprison, pr, pr_list); 159 prisoncount++; 160 mtx_unlock(&allprison_mtx); 161 162 error = jail_attach(td, &jaa); 163 if (error) 164 goto e_dropprref; 165 mtx_lock(&pr->pr_mtx); 166 pr->pr_ref--; 167 mtx_unlock(&pr->pr_mtx); 168 td->td_retval[0] = jaa.jid; 169 return (0); 170 e_dropprref: 171 mtx_lock(&allprison_mtx); 172 LIST_REMOVE(pr, pr_list); 173 prisoncount--; 174 mtx_unlock(&allprison_mtx); 175 e_dropvnref: 176 vfslocked = VFS_LOCK_GIANT(pr->pr_root->v_mount); 177 vrele(pr->pr_root); 178 VFS_UNLOCK_GIANT(vfslocked); 179 e_killmtx: 180 mtx_destroy(&pr->pr_mtx); 181 FREE(pr, M_PRISON); 182 return (error); 183 } 184 185 /* 186 * MPSAFE 187 * 188 * struct jail_attach_args { 189 * int jid; 190 * }; 191 */ 192 int 193 jail_attach(struct thread *td, struct jail_attach_args *uap) 194 { 195 struct proc *p; 196 struct ucred *newcred, *oldcred; 197 struct prison *pr; 198 int vfslocked, error; 199 200 /* 201 * XXX: Note that there is a slight race here if two threads 202 * in the same privileged process attempt to attach to two 203 * different jails at the same time. It is important for 204 * user processes not to do this, or they might end up with 205 * a process root from one prison, but attached to the jail 206 * of another. 207 */ 208 error = suser(td); 209 if (error) 210 return (error); 211 212 p = td->td_proc; 213 mtx_lock(&allprison_mtx); 214 pr = prison_find(uap->jid); 215 if (pr == NULL) { 216 mtx_unlock(&allprison_mtx); 217 return (EINVAL); 218 } 219 pr->pr_ref++; 220 mtx_unlock(&pr->pr_mtx); 221 mtx_unlock(&allprison_mtx); 222 223 vfslocked = VFS_LOCK_GIANT(pr->pr_root->v_mount); 224 vn_lock(pr->pr_root, LK_EXCLUSIVE | LK_RETRY, td); 225 if ((error = change_dir(pr->pr_root, td)) != 0) 226 goto e_unlock; 227 #ifdef MAC 228 if ((error = mac_check_vnode_chroot(td->td_ucred, pr->pr_root))) 229 goto e_unlock; 230 #endif 231 VOP_UNLOCK(pr->pr_root, 0, td); 232 change_root(pr->pr_root, td); 233 VFS_UNLOCK_GIANT(vfslocked); 234 235 newcred = crget(); 236 PROC_LOCK(p); 237 oldcred = p->p_ucred; 238 setsugid(p); 239 crcopy(newcred, oldcred); 240 newcred->cr_prison = pr; 241 p->p_ucred = newcred; 242 PROC_UNLOCK(p); 243 crfree(oldcred); 244 return (0); 245 e_unlock: 246 VOP_UNLOCK(pr->pr_root, 0, td); 247 VFS_UNLOCK_GIANT(vfslocked); 248 mtx_lock(&pr->pr_mtx); 249 pr->pr_ref--; 250 mtx_unlock(&pr->pr_mtx); 251 return (error); 252 } 253 254 /* 255 * Returns a locked prison instance, or NULL on failure. 256 */ 257 static struct prison * 258 prison_find(int prid) 259 { 260 struct prison *pr; 261 262 mtx_assert(&allprison_mtx, MA_OWNED); 263 LIST_FOREACH(pr, &allprison, pr_list) { 264 if (pr->pr_id == prid) { 265 mtx_lock(&pr->pr_mtx); 266 return (pr); 267 } 268 } 269 return (NULL); 270 } 271 272 void 273 prison_free(struct prison *pr) 274 { 275 276 mtx_lock(&allprison_mtx); 277 mtx_lock(&pr->pr_mtx); 278 pr->pr_ref--; 279 if (pr->pr_ref == 0) { 280 LIST_REMOVE(pr, pr_list); 281 mtx_unlock(&pr->pr_mtx); 282 prisoncount--; 283 mtx_unlock(&allprison_mtx); 284 285 TASK_INIT(&pr->pr_task, 0, prison_complete, pr); 286 taskqueue_enqueue(taskqueue_thread, &pr->pr_task); 287 return; 288 } 289 mtx_unlock(&pr->pr_mtx); 290 mtx_unlock(&allprison_mtx); 291 } 292 293 static void 294 prison_complete(void *context, int pending) 295 { 296 struct prison *pr; 297 int vfslocked; 298 299 pr = (struct prison *)context; 300 301 vfslocked = VFS_LOCK_GIANT(pr->pr_root->v_mount); 302 vrele(pr->pr_root); 303 VFS_UNLOCK_GIANT(vfslocked); 304 305 mtx_destroy(&pr->pr_mtx); 306 if (pr->pr_linux != NULL) 307 FREE(pr->pr_linux, M_PRISON); 308 FREE(pr, M_PRISON); 309 } 310 311 void 312 prison_hold(struct prison *pr) 313 { 314 315 mtx_lock(&pr->pr_mtx); 316 pr->pr_ref++; 317 mtx_unlock(&pr->pr_mtx); 318 } 319 320 u_int32_t 321 prison_getip(struct ucred *cred) 322 { 323 324 return (cred->cr_prison->pr_ip); 325 } 326 327 int 328 prison_ip(struct ucred *cred, int flag, u_int32_t *ip) 329 { 330 u_int32_t tmp; 331 332 if (!jailed(cred)) 333 return (0); 334 if (flag) 335 tmp = *ip; 336 else 337 tmp = ntohl(*ip); 338 if (tmp == INADDR_ANY) { 339 if (flag) 340 *ip = cred->cr_prison->pr_ip; 341 else 342 *ip = htonl(cred->cr_prison->pr_ip); 343 return (0); 344 } 345 if (tmp == INADDR_LOOPBACK) { 346 if (flag) 347 *ip = cred->cr_prison->pr_ip; 348 else 349 *ip = htonl(cred->cr_prison->pr_ip); 350 return (0); 351 } 352 if (cred->cr_prison->pr_ip != tmp) 353 return (1); 354 return (0); 355 } 356 357 void 358 prison_remote_ip(struct ucred *cred, int flag, u_int32_t *ip) 359 { 360 u_int32_t tmp; 361 362 if (!jailed(cred)) 363 return; 364 if (flag) 365 tmp = *ip; 366 else 367 tmp = ntohl(*ip); 368 if (tmp == INADDR_LOOPBACK) { 369 if (flag) 370 *ip = cred->cr_prison->pr_ip; 371 else 372 *ip = htonl(cred->cr_prison->pr_ip); 373 return; 374 } 375 return; 376 } 377 378 int 379 prison_if(struct ucred *cred, struct sockaddr *sa) 380 { 381 struct sockaddr_in *sai; 382 int ok; 383 384 sai = (struct sockaddr_in *)sa; 385 if ((sai->sin_family != AF_INET) && jail_socket_unixiproute_only) 386 ok = 1; 387 else if (sai->sin_family != AF_INET) 388 ok = 0; 389 else if (cred->cr_prison->pr_ip != ntohl(sai->sin_addr.s_addr)) 390 ok = 1; 391 else 392 ok = 0; 393 return (ok); 394 } 395 396 /* 397 * Return 0 if jails permit p1 to frob p2, otherwise ESRCH. 398 */ 399 int 400 prison_check(struct ucred *cred1, struct ucred *cred2) 401 { 402 403 if (jailed(cred1)) { 404 if (!jailed(cred2)) 405 return (ESRCH); 406 if (cred2->cr_prison != cred1->cr_prison) 407 return (ESRCH); 408 } 409 410 return (0); 411 } 412 413 /* 414 * Return 1 if the passed credential is in a jail, otherwise 0. 415 */ 416 int 417 jailed(struct ucred *cred) 418 { 419 420 return (cred->cr_prison != NULL); 421 } 422 423 /* 424 * Return the correct hostname for the passed credential. 425 */ 426 void 427 getcredhostname(struct ucred *cred, char *buf, size_t size) 428 { 429 430 if (jailed(cred)) { 431 mtx_lock(&cred->cr_prison->pr_mtx); 432 strlcpy(buf, cred->cr_prison->pr_host, size); 433 mtx_unlock(&cred->cr_prison->pr_mtx); 434 } else 435 strlcpy(buf, hostname, size); 436 } 437 438 /* 439 * Determine whether the subject represented by cred can "see" 440 * status of a mount point. 441 * Returns: 0 for permitted, ENOENT otherwise. 442 * XXX: This function should be called cr_canseemount() and should be 443 * placed in kern_prot.c. 444 */ 445 int 446 prison_canseemount(struct ucred *cred, struct mount *mp) 447 { 448 struct prison *pr; 449 struct statfs *sp; 450 size_t len; 451 452 if (!jailed(cred) || jail_enforce_statfs == 0) 453 return (0); 454 pr = cred->cr_prison; 455 if (pr->pr_root->v_mount == mp) 456 return (0); 457 if (jail_enforce_statfs == 2) 458 return (ENOENT); 459 /* 460 * If jail's chroot directory is set to "/" we should be able to see 461 * all mount-points from inside a jail. 462 * This is ugly check, but this is the only situation when jail's 463 * directory ends with '/'. 464 */ 465 if (strcmp(pr->pr_path, "/") == 0) 466 return (0); 467 len = strlen(pr->pr_path); 468 sp = &mp->mnt_stat; 469 if (strncmp(pr->pr_path, sp->f_mntonname, len) != 0) 470 return (ENOENT); 471 /* 472 * Be sure that we don't have situation where jail's root directory 473 * is "/some/path" and mount point is "/some/pathpath". 474 */ 475 if (sp->f_mntonname[len] != '\0' && sp->f_mntonname[len] != '/') 476 return (ENOENT); 477 return (0); 478 } 479 480 void 481 prison_enforce_statfs(struct ucred *cred, struct mount *mp, struct statfs *sp) 482 { 483 char jpath[MAXPATHLEN]; 484 struct prison *pr; 485 size_t len; 486 487 if (!jailed(cred) || jail_enforce_statfs == 0) 488 return; 489 pr = cred->cr_prison; 490 if (prison_canseemount(cred, mp) != 0) { 491 bzero(sp->f_mntonname, sizeof(sp->f_mntonname)); 492 strlcpy(sp->f_mntonname, "[restricted]", 493 sizeof(sp->f_mntonname)); 494 return; 495 } 496 if (pr->pr_root->v_mount == mp) { 497 /* 498 * Clear current buffer data, so we are sure nothing from 499 * the valid path left there. 500 */ 501 bzero(sp->f_mntonname, sizeof(sp->f_mntonname)); 502 *sp->f_mntonname = '/'; 503 return; 504 } 505 /* 506 * If jail's chroot directory is set to "/" we should be able to see 507 * all mount-points from inside a jail. 508 */ 509 if (strcmp(pr->pr_path, "/") == 0) 510 return; 511 len = strlen(pr->pr_path); 512 strlcpy(jpath, sp->f_mntonname + len, sizeof(jpath)); 513 /* 514 * Clear current buffer data, so we are sure nothing from 515 * the valid path left there. 516 */ 517 bzero(sp->f_mntonname, sizeof(sp->f_mntonname)); 518 if (*jpath == '\0') { 519 /* Should never happen. */ 520 *sp->f_mntonname = '/'; 521 } else { 522 strlcpy(sp->f_mntonname, jpath, sizeof(sp->f_mntonname)); 523 } 524 } 525 526 static int 527 sysctl_jail_list(SYSCTL_HANDLER_ARGS) 528 { 529 struct xprison *xp, *sxp; 530 struct prison *pr; 531 int count, error; 532 533 if (jailed(req->td->td_ucred)) 534 return (0); 535 retry: 536 mtx_lock(&allprison_mtx); 537 count = prisoncount; 538 mtx_unlock(&allprison_mtx); 539 540 if (count == 0) 541 return (0); 542 543 sxp = xp = malloc(sizeof(*xp) * count, M_TEMP, M_WAITOK | M_ZERO); 544 mtx_lock(&allprison_mtx); 545 if (count != prisoncount) { 546 mtx_unlock(&allprison_mtx); 547 free(sxp, M_TEMP); 548 goto retry; 549 } 550 551 LIST_FOREACH(pr, &allprison, pr_list) { 552 mtx_lock(&pr->pr_mtx); 553 xp->pr_version = XPRISON_VERSION; 554 xp->pr_id = pr->pr_id; 555 strlcpy(xp->pr_path, pr->pr_path, sizeof(xp->pr_path)); 556 strlcpy(xp->pr_host, pr->pr_host, sizeof(xp->pr_host)); 557 xp->pr_ip = pr->pr_ip; 558 mtx_unlock(&pr->pr_mtx); 559 xp++; 560 } 561 mtx_unlock(&allprison_mtx); 562 563 error = SYSCTL_OUT(req, sxp, sizeof(*sxp) * count); 564 free(sxp, M_TEMP); 565 if (error) 566 return (error); 567 return (0); 568 } 569 570 SYSCTL_OID(_security_jail, OID_AUTO, list, CTLTYPE_STRUCT | CTLFLAG_RD, 571 NULL, 0, sysctl_jail_list, "S", "List of active jails"); 572 573 static int 574 sysctl_jail_jailed(SYSCTL_HANDLER_ARGS) 575 { 576 int error, injail; 577 578 injail = jailed(req->td->td_ucred); 579 error = SYSCTL_OUT(req, &injail, sizeof(injail)); 580 581 return (error); 582 } 583 SYSCTL_PROC(_security_jail, OID_AUTO, jailed, CTLTYPE_INT | CTLFLAG_RD, 584 NULL, 0, sysctl_jail_jailed, "I", "Process in jail?"); 585