kernel/nsproxy.c

   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 #include <linux/nstree.h>
  30
  31 static struct kmem_cache *nsproxy_cachep;
  32
  33 struct nsproxy init_nsproxy = {
  34         .count                  = REFCOUNT_INIT(1),
  35         .uts_ns                 = &init_uts_ns,
  36 #if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC)
  37         .ipc_ns                 = &init_ipc_ns,
  38 #endif
  39         .mnt_ns                 = NULL,
  40         .pid_ns_for_children    = &init_pid_ns,
  41 #ifdef CONFIG_NET
  42         .net_ns                 = &init_net,
  43 #endif
  44 #ifdef CONFIG_CGROUPS
  45         .cgroup_ns              = &init_cgroup_ns,
  46 #endif
  47 #ifdef CONFIG_TIME_NS
  48         .time_ns                = &init_time_ns,
  49         .time_ns_for_children   = &init_time_ns,
  50 #endif
  51 };
  52
  53 static inline struct nsproxy *create_nsproxy(void)
  54 {
  55         struct nsproxy *nsproxy;
  56
  57         nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL);
  58         if (nsproxy)
  59                 refcount_set(&nsproxy->count, 1);
  60         return nsproxy;
  61 }
  62
  63 static inline void nsproxy_free(struct nsproxy *ns)
  64 {
  65         put_mnt_ns(ns->mnt_ns);
  66         put_uts_ns(ns->uts_ns);
  67         put_ipc_ns(ns->ipc_ns);
  68         put_pid_ns(ns->pid_ns_for_children);
  69         put_time_ns(ns->time_ns);
  70         put_time_ns(ns->time_ns_for_children);
  71         put_cgroup_ns(ns->cgroup_ns);
  72         put_net(ns->net_ns);
  73         kmem_cache_free(nsproxy_cachep, ns);
  74 }
  75
  76 void deactivate_nsproxy(struct nsproxy *ns)
  77 {
  78         nsproxy_ns_active_put(ns);
  79         nsproxy_free(ns);
  80 }
  81
  82 /*
  83  * Create new nsproxy and all of its the associated namespaces.
  84  * Return the newly created nsproxy.  Do not attach this to the task,
  85  * leave it to the caller to do proper locking and attach it to task.
  86  */
  87 static struct nsproxy *create_new_namespaces(u64 flags,
  88         struct task_struct *tsk, struct user_namespace *user_ns,
  89         struct fs_struct *new_fs)
  90 {
  91         struct nsproxy *new_nsp;
  92         int err;
  93
  94         new_nsp = create_nsproxy();
  95         if (!new_nsp)
  96                 return ERR_PTR(-ENOMEM);
  97
  98         new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, user_ns, new_fs);
  99         if (IS_ERR(new_nsp->mnt_ns)) {
 100                 err = PTR_ERR(new_nsp->mnt_ns);
 101                 goto out_ns;
 102         }
 103
 104         new_nsp->uts_ns = copy_utsname(flags, user_ns, tsk->nsproxy->uts_ns);
 105         if (IS_ERR(new_nsp->uts_ns)) {
 106                 err = PTR_ERR(new_nsp->uts_ns);
 107                 goto out_uts;
 108         }
 109
 110         new_nsp->ipc_ns = copy_ipcs(flags, user_ns, tsk->nsproxy->ipc_ns);
 111         if (IS_ERR(new_nsp->ipc_ns)) {
 112                 err = PTR_ERR(new_nsp->ipc_ns);
 113                 goto out_ipc;
 114         }
 115
 116         new_nsp->pid_ns_for_children =
 117                 copy_pid_ns(flags, user_ns, tsk->nsproxy->pid_ns_for_children);
 118         if (IS_ERR(new_nsp->pid_ns_for_children)) {
 119                 err = PTR_ERR(new_nsp->pid_ns_for_children);
 120                 goto out_pid;
 121         }
 122
 123         new_nsp->cgroup_ns = copy_cgroup_ns(flags, user_ns,
 124                                             tsk->nsproxy->cgroup_ns);
 125         if (IS_ERR(new_nsp->cgroup_ns)) {
 126                 err = PTR_ERR(new_nsp->cgroup_ns);
 127                 goto out_cgroup;
 128         }
 129
 130         new_nsp->net_ns = copy_net_ns(flags, user_ns, tsk->nsproxy->net_ns);
 131         if (IS_ERR(new_nsp->net_ns)) {
 132                 err = PTR_ERR(new_nsp->net_ns);
 133                 goto out_net;
 134         }
 135
 136         new_nsp->time_ns_for_children = copy_time_ns(flags, user_ns,
 137                                         tsk->nsproxy->time_ns_for_children);
 138         if (IS_ERR(new_nsp->time_ns_for_children)) {
 139                 err = PTR_ERR(new_nsp->time_ns_for_children);
 140                 goto out_time;
 141         }
 142         new_nsp->time_ns = get_time_ns(tsk->nsproxy->time_ns);
 143
 144         return new_nsp;
 145
 146 out_time:
 147         put_net(new_nsp->net_ns);
 148 out_net:
 149         put_cgroup_ns(new_nsp->cgroup_ns);
 150 out_cgroup:
 151         put_pid_ns(new_nsp->pid_ns_for_children);
 152 out_pid:
 153         put_ipc_ns(new_nsp->ipc_ns);
 154 out_ipc:
 155         put_uts_ns(new_nsp->uts_ns);
 156 out_uts:
 157         put_mnt_ns(new_nsp->mnt_ns);
 158 out_ns:
 159         kmem_cache_free(nsproxy_cachep, new_nsp);
 160         return ERR_PTR(err);
 161 }
 162
 163 /*
 164  * called from clone.  This now handles copy for nsproxy and all
 165  * namespaces therein.
 166  */
 167 int copy_namespaces(u64 flags, struct task_struct *tsk)
 168 {
 169         struct nsproxy *old_ns = tsk->nsproxy;
 170         struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns);
 171         struct nsproxy *new_ns;
 172
 173         if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 174                               CLONE_NEWPID | CLONE_NEWNET |
 175                               CLONE_NEWCGROUP | CLONE_NEWTIME)))) {
 176                 if ((flags & CLONE_VM) ||
 177                     likely(old_ns->time_ns_for_children == old_ns->time_ns)) {
 178                         get_nsproxy(old_ns);
 179                         return 0;
 180                 }
 181         } else if (!ns_capable(user_ns, CAP_SYS_ADMIN))
 182                 return -EPERM;
 183
 184         /*
 185          * CLONE_NEWIPC must detach from the undolist: after switching
 186          * to a new ipc namespace, the semaphore arrays from the old
 187          * namespace are unreachable.  In clone parlance, CLONE_SYSVSEM
 188          * means share undolist with parent, so we must forbid using
 189          * it along with CLONE_NEWIPC.
 190          */
 191         if ((flags & (CLONE_NEWIPC | CLONE_SYSVSEM)) ==
 192                 (CLONE_NEWIPC | CLONE_SYSVSEM))
 193                 return -EINVAL;
 194
 195         new_ns = create_new_namespaces(flags, tsk, user_ns, tsk->fs);
 196         if (IS_ERR(new_ns))
 197                 return  PTR_ERR(new_ns);
 198
 199         if ((flags & CLONE_VM) == 0)
 200                 timens_on_fork(new_ns, tsk);
 201
 202         nsproxy_ns_active_get(new_ns);
 203         tsk->nsproxy = new_ns;
 204         return 0;
 205 }
 206
 207 /*
 208  * Called from unshare. Unshare all the namespaces part of nsproxy.
 209  * On success, returns the new nsproxy.
 210  */
 211 int unshare_nsproxy_namespaces(unsigned long unshare_flags,
 212         struct nsproxy **new_nsp, struct cred *new_cred, struct fs_struct *new_fs)
 213 {
 214         struct user_namespace *user_ns;
 215         int err = 0;
 216
 217         if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 218                                CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP |
 219                                CLONE_NEWTIME)))
 220                 return 0;
 221
 222         user_ns = new_cred ? new_cred->user_ns : current_user_ns();
 223         if (!ns_capable(user_ns, CAP_SYS_ADMIN))
 224                 return -EPERM;
 225
 226         *new_nsp = create_new_namespaces(unshare_flags, current, user_ns,
 227                                          new_fs ? new_fs : current->fs);
 228         if (IS_ERR(*new_nsp)) {
 229                 err = PTR_ERR(*new_nsp);
 230                 goto out;
 231         }
 232
 233 out:
 234         return err;
 235 }
 236
 237 void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
 238 {
 239         struct nsproxy *ns;
 240
 241         might_sleep();
 242
 243         if (new)
 244                 nsproxy_ns_active_get(new);
 245
 246         task_lock(p);
 247         ns = p->nsproxy;
 248         p->nsproxy = new;
 249         task_unlock(p);
 250
 251         if (ns)
 252                 put_nsproxy(ns);
 253 }
 254
 255 void exit_nsproxy_namespaces(struct task_struct *p)
 256 {
 257         switch_task_namespaces(p, NULL);
 258 }
 259
 260 void switch_cred_namespaces(const struct cred *old, const struct cred *new)
 261 {
 262         ns_ref_active_get(new->user_ns);
 263         ns_ref_active_put(old->user_ns);
 264 }
 265
 266 void get_cred_namespaces(struct task_struct *tsk)
 267 {
 268         ns_ref_active_get(tsk->real_cred->user_ns);
 269 }
 270
 271 void exit_cred_namespaces(struct task_struct *tsk)
 272 {
 273         ns_ref_active_put(tsk->real_cred->user_ns);
 274 }
 275
 276 int exec_task_namespaces(void)
 277 {
 278         struct task_struct *tsk = current;
 279         struct nsproxy *new;
 280
 281         if (tsk->nsproxy->time_ns_for_children == tsk->nsproxy->time_ns)
 282                 return 0;
 283
 284         new = create_new_namespaces(0, tsk, current_user_ns(), tsk->fs);
 285         if (IS_ERR(new))
 286                 return PTR_ERR(new);
 287
 288         timens_on_fork(new, tsk);
 289         switch_task_namespaces(tsk, new);
 290         return 0;
 291 }
 292
 293 static int check_setns_flags(unsigned long flags)
 294 {
 295         if (!flags || (flags & ~(CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 296                                  CLONE_NEWNET | CLONE_NEWTIME | CLONE_NEWUSER |
 297                                  CLONE_NEWPID | CLONE_NEWCGROUP)))
 298                 return -EINVAL;
 299
 300 #ifndef CONFIG_USER_NS
 301         if (flags & CLONE_NEWUSER)
 302                 return -EINVAL;
 303 #endif
 304 #ifndef CONFIG_PID_NS
 305         if (flags & CLONE_NEWPID)
 306                 return -EINVAL;
 307 #endif
 308 #ifndef CONFIG_UTS_NS
 309         if (flags & CLONE_NEWUTS)
 310                 return -EINVAL;
 311 #endif
 312 #ifndef CONFIG_IPC_NS
 313         if (flags & CLONE_NEWIPC)
 314                 return -EINVAL;
 315 #endif
 316 #ifndef CONFIG_CGROUPS
 317         if (flags & CLONE_NEWCGROUP)
 318                 return -EINVAL;
 319 #endif
 320 #ifndef CONFIG_NET_NS
 321         if (flags & CLONE_NEWNET)
 322                 return -EINVAL;
 323 #endif
 324 #ifndef CONFIG_TIME_NS
 325         if (flags & CLONE_NEWTIME)
 326                 return -EINVAL;
 327 #endif
 328
 329         return 0;
 330 }
 331
 332 static void put_nsset(struct nsset *nsset)
 333 {
 334         unsigned flags = nsset->flags;
 335
 336         if (flags & CLONE_NEWUSER)
 337                 put_cred(nsset_cred(nsset));
 338         /*
 339          * We only created a temporary copy if we attached to more than just
 340          * the mount namespace.
 341          */
 342         if (nsset->fs && (flags & CLONE_NEWNS) && (flags & ~CLONE_NEWNS))
 343                 free_fs_struct(nsset->fs);
 344         if (nsset->nsproxy)
 345                 nsproxy_free(nsset->nsproxy);
 346 }
 347
 348 static int prepare_nsset(unsigned flags, struct nsset *nsset)
 349 {
 350         struct task_struct *me = current;
 351
 352         nsset->nsproxy = create_new_namespaces(0, me, current_user_ns(), me->fs);
 353         if (IS_ERR(nsset->nsproxy))
 354                 return PTR_ERR(nsset->nsproxy);
 355
 356         if (flags & CLONE_NEWUSER)
 357                 nsset->cred = prepare_creds();
 358         else
 359                 nsset->cred = current_cred();
 360         if (!nsset->cred)
 361                 goto out;
 362
 363         /* Only create a temporary copy of fs_struct if we really need to. */
 364         if (flags == CLONE_NEWNS) {
 365                 nsset->fs = me->fs;
 366         } else if (flags & CLONE_NEWNS) {
 367                 nsset->fs = copy_fs_struct(me->fs);
 368                 if (!nsset->fs)
 369                         goto out;
 370         }
 371
 372         nsset->flags = flags;
 373         return 0;
 374
 375 out:
 376         put_nsset(nsset);
 377         return -ENOMEM;
 378 }
 379
 380 static inline int validate_ns(struct nsset *nsset, struct ns_common *ns)
 381 {
 382         return ns->ops->install(nsset, ns);
 383 }
 384
 385 /*
 386  * This is the inverse operation to unshare().
 387  * Ordering is equivalent to the standard ordering used everywhere else
 388  * during unshare and process creation. The switch to the new set of
 389  * namespaces occurs at the point of no return after installation of
 390  * all requested namespaces was successful in commit_nsset().
 391  */
 392 static int validate_nsset(struct nsset *nsset, struct pid *pid)
 393 {
 394         int ret = 0;
 395         unsigned flags = nsset->flags;
 396         struct user_namespace *user_ns = NULL;
 397         struct pid_namespace *pid_ns = NULL;
 398         struct nsproxy *nsp;
 399         struct task_struct *tsk;
 400
 401         /* Take a "snapshot" of the target task's namespaces. */
 402         rcu_read_lock();
 403         tsk = pid_task(pid, PIDTYPE_PID);
 404         if (!tsk) {
 405                 rcu_read_unlock();
 406                 return -ESRCH;
 407         }
 408
 409         if (!ptrace_may_access(tsk, PTRACE_MODE_READ_REALCREDS)) {
 410                 rcu_read_unlock();
 411                 return -EPERM;
 412         }
 413
 414         task_lock(tsk);
 415         nsp = tsk->nsproxy;
 416         if (nsp)
 417                 get_nsproxy(nsp);
 418         task_unlock(tsk);
 419         if (!nsp) {
 420                 rcu_read_unlock();
 421                 return -ESRCH;
 422         }
 423
 424 #ifdef CONFIG_PID_NS
 425         if (flags & CLONE_NEWPID) {
 426                 pid_ns = task_active_pid_ns(tsk);
 427                 if (unlikely(!pid_ns)) {
 428                         rcu_read_unlock();
 429                         ret = -ESRCH;
 430                         goto out;
 431                 }
 432                 get_pid_ns(pid_ns);
 433         }
 434 #endif
 435
 436 #ifdef CONFIG_USER_NS
 437         if (flags & CLONE_NEWUSER)
 438                 user_ns = get_user_ns(__task_cred(tsk)->user_ns);
 439 #endif
 440         rcu_read_unlock();
 441
 442         /*
 443          * Install requested namespaces. The caller will have
 444          * verified earlier that the requested namespaces are
 445          * supported on this kernel. We don't report errors here
 446          * if a namespace is requested that isn't supported.
 447          */
 448 #ifdef CONFIG_USER_NS
 449         if (flags & CLONE_NEWUSER) {
 450                 ret = validate_ns(nsset, &user_ns->ns);
 451                 if (ret)
 452                         goto out;
 453         }
 454 #endif
 455
 456         if (flags & CLONE_NEWNS) {
 457                 ret = validate_ns(nsset, from_mnt_ns(nsp->mnt_ns));
 458                 if (ret)
 459                         goto out;
 460         }
 461
 462 #ifdef CONFIG_UTS_NS
 463         if (flags & CLONE_NEWUTS) {
 464                 ret = validate_ns(nsset, &nsp->uts_ns->ns);
 465                 if (ret)
 466                         goto out;
 467         }
 468 #endif
 469
 470 #ifdef CONFIG_IPC_NS
 471         if (flags & CLONE_NEWIPC) {
 472                 ret = validate_ns(nsset, &nsp->ipc_ns->ns);
 473                 if (ret)
 474                         goto out;
 475         }
 476 #endif
 477
 478 #ifdef CONFIG_PID_NS
 479         if (flags & CLONE_NEWPID) {
 480                 ret = validate_ns(nsset, &pid_ns->ns);
 481                 if (ret)
 482                         goto out;
 483         }
 484 #endif
 485
 486 #ifdef CONFIG_CGROUPS
 487         if (flags & CLONE_NEWCGROUP) {
 488                 ret = validate_ns(nsset, &nsp->cgroup_ns->ns);
 489                 if (ret)
 490                         goto out;
 491         }
 492 #endif
 493
 494 #ifdef CONFIG_NET_NS
 495         if (flags & CLONE_NEWNET) {
 496                 ret = validate_ns(nsset, &nsp->net_ns->ns);
 497                 if (ret)
 498                         goto out;
 499         }
 500 #endif
 501
 502 #ifdef CONFIG_TIME_NS
 503         if (flags & CLONE_NEWTIME) {
 504                 ret = validate_ns(nsset, &nsp->time_ns->ns);
 505                 if (ret)
 506                         goto out;
 507         }
 508 #endif
 509
 510 out:
 511         if (pid_ns)
 512                 put_pid_ns(pid_ns);
 513         if (nsp)
 514                 put_nsproxy(nsp);
 515         put_user_ns(user_ns);
 516
 517         return ret;
 518 }
 519
 520 /*
 521  * This is the point of no return. There are just a few namespaces
 522  * that do some actual work here and it's sufficiently minimal that
 523  * a separate ns_common operation seems unnecessary for now.
 524  * Unshare is doing the same thing. If we'll end up needing to do
 525  * more in a given namespace or a helper here is ultimately not
 526  * exported anymore a simple commit handler for each namespace
 527  * should be added to ns_common.
 528  */
 529 static void commit_nsset(struct nsset *nsset)
 530 {
 531         unsigned flags = nsset->flags;
 532         struct task_struct *me = current;
 533
 534 #ifdef CONFIG_USER_NS
 535         if (flags & CLONE_NEWUSER) {
 536                 /* transfer ownership */
 537                 commit_creds(nsset_cred(nsset));
 538                 nsset->cred = NULL;
 539         }
 540 #endif
 541
 542         /* We only need to commit if we have used a temporary fs_struct. */
 543         if ((flags & CLONE_NEWNS) && (flags & ~CLONE_NEWNS)) {
 544                 set_fs_root(me->fs, &nsset->fs->root);
 545                 set_fs_pwd(me->fs, &nsset->fs->pwd);
 546         }
 547
 548 #ifdef CONFIG_IPC_NS
 549         if (flags & CLONE_NEWIPC)
 550                 exit_sem(me);
 551 #endif
 552
 553 #ifdef CONFIG_TIME_NS
 554         if (flags & CLONE_NEWTIME)
 555                 timens_commit(me, nsset->nsproxy->time_ns);
 556 #endif
 557
 558         /* transfer ownership */
 559         switch_task_namespaces(me, nsset->nsproxy);
 560         nsset->nsproxy = NULL;
 561 }
 562
 563 SYSCALL_DEFINE2(setns, int, fd, int, flags)
 564 {
 565         CLASS(fd, f)(fd);
 566         struct ns_common *ns = NULL;
 567         struct nsset nsset = {};
 568         int err = 0;
 569
 570         if (fd_empty(f))
 571                 return -EBADF;
 572
 573         if (proc_ns_file(fd_file(f))) {
 574                 ns = get_proc_ns(file_inode(fd_file(f)));
 575                 if (flags && (ns->ns_type != flags))
 576                         err = -EINVAL;
 577                 flags = ns->ns_type;
 578         } else if (!IS_ERR(pidfd_pid(fd_file(f)))) {
 579                 err = check_setns_flags(flags);
 580         } else {
 581                 err = -EINVAL;
 582         }
 583         if (err)
 584                 goto out;
 585
 586         err = prepare_nsset(flags, &nsset);
 587         if (err)
 588                 goto out;
 589
 590         if (proc_ns_file(fd_file(f)))
 591                 err = validate_ns(&nsset, ns);
 592         else
 593                 err = validate_nsset(&nsset, pidfd_pid(fd_file(f)));
 594         if (!err) {
 595                 commit_nsset(&nsset);
 596                 perf_event_namespaces(current);
 597         }
 598         put_nsset(&nsset);
 599 out:
 600         return err;
 601 }
 602
 603 int __init nsproxy_cache_init(void)
 604 {
 605         nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC|SLAB_ACCOUNT);
 606         return 0;
 607 }