1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2006 IBM Corporation 4 * 5 * Author: Serge Hallyn <serue@us.ibm.com> 6 * 7 * Jun 2006 - namespaces support 8 * OpenVZ, SWsoft Inc. 9 * Pavel Emelianov <xemul@openvz.org> 10 */ 11 12 #include <linux/slab.h> 13 #include <linux/export.h> 14 #include <linux/nsproxy.h> 15 #include <linux/init_task.h> 16 #include <linux/mnt_namespace.h> 17 #include <linux/utsname.h> 18 #include <linux/pid_namespace.h> 19 #include <net/net_namespace.h> 20 #include <linux/ipc_namespace.h> 21 #include <linux/time_namespace.h> 22 #include <linux/fs_struct.h> 23 #include <linux/proc_fs.h> 24 #include <linux/proc_ns.h> 25 #include <linux/file.h> 26 #include <linux/syscalls.h> 27 #include <linux/cgroup.h> 28 #include <linux/perf_event.h> 29 30 static struct kmem_cache *nsproxy_cachep; 31 32 struct nsproxy init_nsproxy = { 33 .count = ATOMIC_INIT(1), 34 .uts_ns = &init_uts_ns, 35 #if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC) 36 .ipc_ns = &init_ipc_ns, 37 #endif 38 .mnt_ns = NULL, 39 .pid_ns_for_children = &init_pid_ns, 40 #ifdef CONFIG_NET 41 .net_ns = &init_net, 42 #endif 43 #ifdef CONFIG_CGROUPS 44 .cgroup_ns = &init_cgroup_ns, 45 #endif 46 #ifdef CONFIG_TIME_NS 47 .time_ns = &init_time_ns, 48 .time_ns_for_children = &init_time_ns, 49 #endif 50 }; 51 52 static inline struct nsproxy *create_nsproxy(void) 53 { 54 struct nsproxy *nsproxy; 55 56 nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL); 57 if (nsproxy) 58 atomic_set(&nsproxy->count, 1); 59 return nsproxy; 60 } 61 62 /* 63 * Create new nsproxy and all of its the associated namespaces. 64 * Return the newly created nsproxy. Do not attach this to the task, 65 * leave it to the caller to do proper locking and attach it to task. 66 */ 67 static struct nsproxy *create_new_namespaces(unsigned long flags, 68 struct task_struct *tsk, struct user_namespace *user_ns, 69 struct fs_struct *new_fs) 70 { 71 struct nsproxy *new_nsp; 72 int err; 73 74 new_nsp = create_nsproxy(); 75 if (!new_nsp) 76 return ERR_PTR(-ENOMEM); 77 78 new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, user_ns, new_fs); 79 if (IS_ERR(new_nsp->mnt_ns)) { 80 err = PTR_ERR(new_nsp->mnt_ns); 81 goto out_ns; 82 } 83 84 new_nsp->uts_ns = copy_utsname(flags, user_ns, tsk->nsproxy->uts_ns); 85 if (IS_ERR(new_nsp->uts_ns)) { 86 err = PTR_ERR(new_nsp->uts_ns); 87 goto out_uts; 88 } 89 90 new_nsp->ipc_ns = copy_ipcs(flags, user_ns, tsk->nsproxy->ipc_ns); 91 if (IS_ERR(new_nsp->ipc_ns)) { 92 err = PTR_ERR(new_nsp->ipc_ns); 93 goto out_ipc; 94 } 95 96 new_nsp->pid_ns_for_children = 97 copy_pid_ns(flags, user_ns, tsk->nsproxy->pid_ns_for_children); 98 if (IS_ERR(new_nsp->pid_ns_for_children)) { 99 err = PTR_ERR(new_nsp->pid_ns_for_children); 100 goto out_pid; 101 } 102 103 new_nsp->cgroup_ns = copy_cgroup_ns(flags, user_ns, 104 tsk->nsproxy->cgroup_ns); 105 if (IS_ERR(new_nsp->cgroup_ns)) { 106 err = PTR_ERR(new_nsp->cgroup_ns); 107 goto out_cgroup; 108 } 109 110 new_nsp->net_ns = copy_net_ns(flags, user_ns, tsk->nsproxy->net_ns); 111 if (IS_ERR(new_nsp->net_ns)) { 112 err = PTR_ERR(new_nsp->net_ns); 113 goto out_net; 114 } 115 116 new_nsp->time_ns_for_children = copy_time_ns(flags, user_ns, 117 tsk->nsproxy->time_ns_for_children); 118 if (IS_ERR(new_nsp->time_ns_for_children)) { 119 err = PTR_ERR(new_nsp->time_ns_for_children); 120 goto out_time; 121 } 122 new_nsp->time_ns = get_time_ns(tsk->nsproxy->time_ns); 123 124 return new_nsp; 125 126 out_time: 127 put_net(new_nsp->net_ns); 128 out_net: 129 put_cgroup_ns(new_nsp->cgroup_ns); 130 out_cgroup: 131 if (new_nsp->pid_ns_for_children) 132 put_pid_ns(new_nsp->pid_ns_for_children); 133 out_pid: 134 if (new_nsp->ipc_ns) 135 put_ipc_ns(new_nsp->ipc_ns); 136 out_ipc: 137 if (new_nsp->uts_ns) 138 put_uts_ns(new_nsp->uts_ns); 139 out_uts: 140 if (new_nsp->mnt_ns) 141 put_mnt_ns(new_nsp->mnt_ns); 142 out_ns: 143 kmem_cache_free(nsproxy_cachep, new_nsp); 144 return ERR_PTR(err); 145 } 146 147 /* 148 * called from clone. This now handles copy for nsproxy and all 149 * namespaces therein. 150 */ 151 int copy_namespaces(unsigned long flags, struct task_struct *tsk) 152 { 153 struct nsproxy *old_ns = tsk->nsproxy; 154 struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns); 155 struct nsproxy *new_ns; 156 157 if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | 158 CLONE_NEWPID | CLONE_NEWNET | 159 CLONE_NEWCGROUP | CLONE_NEWTIME)))) { 160 if (likely(old_ns->time_ns_for_children == old_ns->time_ns)) { 161 get_nsproxy(old_ns); 162 return 0; 163 } 164 } else if (!ns_capable(user_ns, CAP_SYS_ADMIN)) 165 return -EPERM; 166 167 /* 168 * CLONE_NEWIPC must detach from the undolist: after switching 169 * to a new ipc namespace, the semaphore arrays from the old 170 * namespace are unreachable. In clone parlance, CLONE_SYSVSEM 171 * means share undolist with parent, so we must forbid using 172 * it along with CLONE_NEWIPC. 173 */ 174 if ((flags & (CLONE_NEWIPC | CLONE_SYSVSEM)) == 175 (CLONE_NEWIPC | CLONE_SYSVSEM)) 176 return -EINVAL; 177 178 new_ns = create_new_namespaces(flags, tsk, user_ns, tsk->fs); 179 if (IS_ERR(new_ns)) 180 return PTR_ERR(new_ns); 181 182 if ((flags & CLONE_VM) == 0) 183 timens_on_fork(new_ns, tsk); 184 185 tsk->nsproxy = new_ns; 186 return 0; 187 } 188 189 void free_nsproxy(struct nsproxy *ns) 190 { 191 if (ns->mnt_ns) 192 put_mnt_ns(ns->mnt_ns); 193 if (ns->uts_ns) 194 put_uts_ns(ns->uts_ns); 195 if (ns->ipc_ns) 196 put_ipc_ns(ns->ipc_ns); 197 if (ns->pid_ns_for_children) 198 put_pid_ns(ns->pid_ns_for_children); 199 if (ns->time_ns) 200 put_time_ns(ns->time_ns); 201 if (ns->time_ns_for_children) 202 put_time_ns(ns->time_ns_for_children); 203 put_cgroup_ns(ns->cgroup_ns); 204 put_net(ns->net_ns); 205 kmem_cache_free(nsproxy_cachep, ns); 206 } 207 208 /* 209 * Called from unshare. Unshare all the namespaces part of nsproxy. 210 * On success, returns the new nsproxy. 211 */ 212 int unshare_nsproxy_namespaces(unsigned long unshare_flags, 213 struct nsproxy **new_nsp, struct cred *new_cred, struct fs_struct *new_fs) 214 { 215 struct user_namespace *user_ns; 216 int err = 0; 217 218 if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | 219 CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP | 220 CLONE_NEWTIME))) 221 return 0; 222 223 user_ns = new_cred ? new_cred->user_ns : current_user_ns(); 224 if (!ns_capable(user_ns, CAP_SYS_ADMIN)) 225 return -EPERM; 226 227 *new_nsp = create_new_namespaces(unshare_flags, current, user_ns, 228 new_fs ? new_fs : current->fs); 229 if (IS_ERR(*new_nsp)) { 230 err = PTR_ERR(*new_nsp); 231 goto out; 232 } 233 234 out: 235 return err; 236 } 237 238 void switch_task_namespaces(struct task_struct *p, struct nsproxy *new) 239 { 240 struct nsproxy *ns; 241 242 might_sleep(); 243 244 task_lock(p); 245 ns = p->nsproxy; 246 p->nsproxy = new; 247 task_unlock(p); 248 249 if (ns) 250 put_nsproxy(ns); 251 } 252 253 void exit_task_namespaces(struct task_struct *p) 254 { 255 switch_task_namespaces(p, NULL); 256 } 257 258 static int check_setns_flags(unsigned long flags) 259 { 260 if (!flags || (flags & ~(CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | 261 CLONE_NEWNET | CLONE_NEWTIME | CLONE_NEWUSER | 262 CLONE_NEWPID | CLONE_NEWCGROUP))) 263 return -EINVAL; 264 265 #ifndef CONFIG_USER_NS 266 if (flags & CLONE_NEWUSER) 267 return -EINVAL; 268 #endif 269 #ifndef CONFIG_PID_NS 270 if (flags & CLONE_NEWPID) 271 return -EINVAL; 272 #endif 273 #ifndef CONFIG_UTS_NS 274 if (flags & CLONE_NEWUTS) 275 return -EINVAL; 276 #endif 277 #ifndef CONFIG_IPC_NS 278 if (flags & CLONE_NEWIPC) 279 return -EINVAL; 280 #endif 281 #ifndef CONFIG_CGROUPS 282 if (flags & CLONE_NEWCGROUP) 283 return -EINVAL; 284 #endif 285 #ifndef CONFIG_NET_NS 286 if (flags & CLONE_NEWNET) 287 return -EINVAL; 288 #endif 289 #ifndef CONFIG_TIME_NS 290 if (flags & CLONE_NEWTIME) 291 return -EINVAL; 292 #endif 293 294 return 0; 295 } 296 297 static void put_nsset(struct nsset *nsset) 298 { 299 unsigned flags = nsset->flags; 300 301 if (flags & CLONE_NEWUSER) 302 put_cred(nsset_cred(nsset)); 303 /* 304 * We only created a temporary copy if we attached to more than just 305 * the mount namespace. 306 */ 307 if (nsset->fs && (flags & CLONE_NEWNS) && (flags & ~CLONE_NEWNS)) 308 free_fs_struct(nsset->fs); 309 if (nsset->nsproxy) 310 free_nsproxy(nsset->nsproxy); 311 } 312 313 static int prepare_nsset(unsigned flags, struct nsset *nsset) 314 { 315 struct task_struct *me = current; 316 317 nsset->nsproxy = create_new_namespaces(0, me, current_user_ns(), me->fs); 318 if (IS_ERR(nsset->nsproxy)) 319 return PTR_ERR(nsset->nsproxy); 320 321 if (flags & CLONE_NEWUSER) 322 nsset->cred = prepare_creds(); 323 else 324 nsset->cred = current_cred(); 325 if (!nsset->cred) 326 goto out; 327 328 /* Only create a temporary copy of fs_struct if we really need to. */ 329 if (flags == CLONE_NEWNS) { 330 nsset->fs = me->fs; 331 } else if (flags & CLONE_NEWNS) { 332 nsset->fs = copy_fs_struct(me->fs); 333 if (!nsset->fs) 334 goto out; 335 } 336 337 nsset->flags = flags; 338 return 0; 339 340 out: 341 put_nsset(nsset); 342 return -ENOMEM; 343 } 344 345 static inline int validate_ns(struct nsset *nsset, struct ns_common *ns) 346 { 347 return ns->ops->install(nsset, ns); 348 } 349 350 /* 351 * This is the inverse operation to unshare(). 352 * Ordering is equivalent to the standard ordering used everywhere else 353 * during unshare and process creation. The switch to the new set of 354 * namespaces occurs at the point of no return after installation of 355 * all requested namespaces was successful in commit_nsset(). 356 */ 357 static int validate_nsset(struct nsset *nsset, struct pid *pid) 358 { 359 int ret = 0; 360 unsigned flags = nsset->flags; 361 struct user_namespace *user_ns = NULL; 362 struct pid_namespace *pid_ns = NULL; 363 struct nsproxy *nsp; 364 struct task_struct *tsk; 365 366 /* Take a "snapshot" of the target task's namespaces. */ 367 rcu_read_lock(); 368 tsk = pid_task(pid, PIDTYPE_PID); 369 if (!tsk) { 370 rcu_read_unlock(); 371 return -ESRCH; 372 } 373 374 if (!ptrace_may_access(tsk, PTRACE_MODE_READ_REALCREDS)) { 375 rcu_read_unlock(); 376 return -EPERM; 377 } 378 379 task_lock(tsk); 380 nsp = tsk->nsproxy; 381 if (nsp) 382 get_nsproxy(nsp); 383 task_unlock(tsk); 384 if (!nsp) { 385 rcu_read_unlock(); 386 return -ESRCH; 387 } 388 389 #ifdef CONFIG_PID_NS 390 if (flags & CLONE_NEWPID) { 391 pid_ns = task_active_pid_ns(tsk); 392 if (unlikely(!pid_ns)) { 393 rcu_read_unlock(); 394 ret = -ESRCH; 395 goto out; 396 } 397 get_pid_ns(pid_ns); 398 } 399 #endif 400 401 #ifdef CONFIG_USER_NS 402 if (flags & CLONE_NEWUSER) 403 user_ns = get_user_ns(__task_cred(tsk)->user_ns); 404 #endif 405 rcu_read_unlock(); 406 407 /* 408 * Install requested namespaces. The caller will have 409 * verified earlier that the requested namespaces are 410 * supported on this kernel. We don't report errors here 411 * if a namespace is requested that isn't supported. 412 */ 413 #ifdef CONFIG_USER_NS 414 if (flags & CLONE_NEWUSER) { 415 ret = validate_ns(nsset, &user_ns->ns); 416 if (ret) 417 goto out; 418 } 419 #endif 420 421 if (flags & CLONE_NEWNS) { 422 ret = validate_ns(nsset, from_mnt_ns(nsp->mnt_ns)); 423 if (ret) 424 goto out; 425 } 426 427 #ifdef CONFIG_UTS_NS 428 if (flags & CLONE_NEWUTS) { 429 ret = validate_ns(nsset, &nsp->uts_ns->ns); 430 if (ret) 431 goto out; 432 } 433 #endif 434 435 #ifdef CONFIG_IPC_NS 436 if (flags & CLONE_NEWIPC) { 437 ret = validate_ns(nsset, &nsp->ipc_ns->ns); 438 if (ret) 439 goto out; 440 } 441 #endif 442 443 #ifdef CONFIG_PID_NS 444 if (flags & CLONE_NEWPID) { 445 ret = validate_ns(nsset, &pid_ns->ns); 446 if (ret) 447 goto out; 448 } 449 #endif 450 451 #ifdef CONFIG_CGROUPS 452 if (flags & CLONE_NEWCGROUP) { 453 ret = validate_ns(nsset, &nsp->cgroup_ns->ns); 454 if (ret) 455 goto out; 456 } 457 #endif 458 459 #ifdef CONFIG_NET_NS 460 if (flags & CLONE_NEWNET) { 461 ret = validate_ns(nsset, &nsp->net_ns->ns); 462 if (ret) 463 goto out; 464 } 465 #endif 466 467 #ifdef CONFIG_TIME_NS 468 if (flags & CLONE_NEWTIME) { 469 ret = validate_ns(nsset, &nsp->time_ns->ns); 470 if (ret) 471 goto out; 472 } 473 #endif 474 475 out: 476 if (pid_ns) 477 put_pid_ns(pid_ns); 478 if (nsp) 479 put_nsproxy(nsp); 480 put_user_ns(user_ns); 481 482 return ret; 483 } 484 485 /* 486 * This is the point of no return. There are just a few namespaces 487 * that do some actual work here and it's sufficiently minimal that 488 * a separate ns_common operation seems unnecessary for now. 489 * Unshare is doing the same thing. If we'll end up needing to do 490 * more in a given namespace or a helper here is ultimately not 491 * exported anymore a simple commit handler for each namespace 492 * should be added to ns_common. 493 */ 494 static void commit_nsset(struct nsset *nsset) 495 { 496 unsigned flags = nsset->flags; 497 struct task_struct *me = current; 498 499 #ifdef CONFIG_USER_NS 500 if (flags & CLONE_NEWUSER) { 501 /* transfer ownership */ 502 commit_creds(nsset_cred(nsset)); 503 nsset->cred = NULL; 504 } 505 #endif 506 507 /* We only need to commit if we have used a temporary fs_struct. */ 508 if ((flags & CLONE_NEWNS) && (flags & ~CLONE_NEWNS)) { 509 set_fs_root(me->fs, &nsset->fs->root); 510 set_fs_pwd(me->fs, &nsset->fs->pwd); 511 } 512 513 #ifdef CONFIG_IPC_NS 514 if (flags & CLONE_NEWIPC) 515 exit_sem(me); 516 #endif 517 518 #ifdef CONFIG_TIME_NS 519 if (flags & CLONE_NEWTIME) 520 timens_commit(me, nsset->nsproxy->time_ns); 521 #endif 522 523 /* transfer ownership */ 524 switch_task_namespaces(me, nsset->nsproxy); 525 nsset->nsproxy = NULL; 526 } 527 528 SYSCALL_DEFINE2(setns, int, fd, int, flags) 529 { 530 struct file *file; 531 struct ns_common *ns = NULL; 532 struct nsset nsset = {}; 533 int err = 0; 534 535 file = fget(fd); 536 if (!file) 537 return -EBADF; 538 539 if (proc_ns_file(file)) { 540 ns = get_proc_ns(file_inode(file)); 541 if (flags && (ns->ops->type != flags)) 542 err = -EINVAL; 543 flags = ns->ops->type; 544 } else if (!IS_ERR(pidfd_pid(file))) { 545 err = check_setns_flags(flags); 546 } else { 547 err = -EINVAL; 548 } 549 if (err) 550 goto out; 551 552 err = prepare_nsset(flags, &nsset); 553 if (err) 554 goto out; 555 556 if (proc_ns_file(file)) 557 err = validate_ns(&nsset, ns); 558 else 559 err = validate_nsset(&nsset, file->private_data); 560 if (!err) { 561 commit_nsset(&nsset); 562 perf_event_namespaces(current); 563 } 564 put_nsset(&nsset); 565 out: 566 fput(file); 567 return err; 568 } 569 570 int __init nsproxy_cache_init(void) 571 { 572 nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC|SLAB_ACCOUNT); 573 return 0; 574 } 575