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
  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 ((flags & CLONE_VM) ||
 161                     likely(old_ns->time_ns_for_children == old_ns->time_ns)) {
 162                         get_nsproxy(old_ns);
 163                         return 0;
 164                 }
 165         } else if (!ns_capable(user_ns, CAP_SYS_ADMIN))
 166                 return -EPERM;
 167
 168         /*
 169          * CLONE_NEWIPC must detach from the undolist: after switching
 170          * to a new ipc namespace, the semaphore arrays from the old
 171          * namespace are unreachable.  In clone parlance, CLONE_SYSVSEM
 172          * means share undolist with parent, so we must forbid using
 173          * it along with CLONE_NEWIPC.
 174          */
 175         if ((flags & (CLONE_NEWIPC | CLONE_SYSVSEM)) ==
 176                 (CLONE_NEWIPC | CLONE_SYSVSEM))
 177                 return -EINVAL;
 178
 179         new_ns = create_new_namespaces(flags, tsk, user_ns, tsk->fs);
 180         if (IS_ERR(new_ns))
 181                 return  PTR_ERR(new_ns);
 182
 183         if ((flags & CLONE_VM) == 0)
 184                 timens_on_fork(new_ns, tsk);
 185
 186         tsk->nsproxy = new_ns;
 187         return 0;
 188 }
 189
 190 void free_nsproxy(struct nsproxy *ns)
 191 {
 192         if (ns->mnt_ns)
 193                 put_mnt_ns(ns->mnt_ns);
 194         if (ns->uts_ns)
 195                 put_uts_ns(ns->uts_ns);
 196         if (ns->ipc_ns)
 197                 put_ipc_ns(ns->ipc_ns);
 198         if (ns->pid_ns_for_children)
 199                 put_pid_ns(ns->pid_ns_for_children);
 200         if (ns->time_ns)
 201                 put_time_ns(ns->time_ns);
 202         if (ns->time_ns_for_children)
 203                 put_time_ns(ns->time_ns_for_children);
 204         put_cgroup_ns(ns->cgroup_ns);
 205         put_net(ns->net_ns);
 206         kmem_cache_free(nsproxy_cachep, ns);
 207 }
 208
 209 /*
 210  * Called from unshare. Unshare all the namespaces part of nsproxy.
 211  * On success, returns the new nsproxy.
 212  */
 213 int unshare_nsproxy_namespaces(unsigned long unshare_flags,
 214         struct nsproxy **new_nsp, struct cred *new_cred, struct fs_struct *new_fs)
 215 {
 216         struct user_namespace *user_ns;
 217         int err = 0;
 218
 219         if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 220                                CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP |
 221                                CLONE_NEWTIME)))
 222                 return 0;
 223
 224         user_ns = new_cred ? new_cred->user_ns : current_user_ns();
 225         if (!ns_capable(user_ns, CAP_SYS_ADMIN))
 226                 return -EPERM;
 227
 228         *new_nsp = create_new_namespaces(unshare_flags, current, user_ns,
 229                                          new_fs ? new_fs : current->fs);
 230         if (IS_ERR(*new_nsp)) {
 231                 err = PTR_ERR(*new_nsp);
 232                 goto out;
 233         }
 234
 235 out:
 236         return err;
 237 }
 238
 239 void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
 240 {
 241         struct nsproxy *ns;
 242
 243         might_sleep();
 244
 245         task_lock(p);
 246         ns = p->nsproxy;
 247         p->nsproxy = new;
 248         task_unlock(p);
 249
 250         if (ns)
 251                 put_nsproxy(ns);
 252 }
 253
 254 void exit_task_namespaces(struct task_struct *p)
 255 {
 256         switch_task_namespaces(p, NULL);
 257 }
 258
 259 int exec_task_namespaces(void)
 260 {
 261         struct task_struct *tsk = current;
 262         struct nsproxy *new;
 263
 264         if (tsk->nsproxy->time_ns_for_children == tsk->nsproxy->time_ns)
 265                 return 0;
 266
 267         new = create_new_namespaces(0, tsk, current_user_ns(), tsk->fs);
 268         if (IS_ERR(new))
 269                 return PTR_ERR(new);
 270
 271         timens_on_fork(new, tsk);
 272         switch_task_namespaces(tsk, new);
 273         return 0;
 274 }
 275
 276 static int check_setns_flags(unsigned long flags)
 277 {
 278         if (!flags || (flags & ~(CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 279                                  CLONE_NEWNET | CLONE_NEWTIME | CLONE_NEWUSER |
 280                                  CLONE_NEWPID | CLONE_NEWCGROUP)))
 281                 return -EINVAL;
 282
 283 #ifndef CONFIG_USER_NS
 284         if (flags & CLONE_NEWUSER)
 285                 return -EINVAL;
 286 #endif
 287 #ifndef CONFIG_PID_NS
 288         if (flags & CLONE_NEWPID)
 289                 return -EINVAL;
 290 #endif
 291 #ifndef CONFIG_UTS_NS
 292         if (flags & CLONE_NEWUTS)
 293                 return -EINVAL;
 294 #endif
 295 #ifndef CONFIG_IPC_NS
 296         if (flags & CLONE_NEWIPC)
 297                 return -EINVAL;
 298 #endif
 299 #ifndef CONFIG_CGROUPS
 300         if (flags & CLONE_NEWCGROUP)
 301                 return -EINVAL;
 302 #endif
 303 #ifndef CONFIG_NET_NS
 304         if (flags & CLONE_NEWNET)
 305                 return -EINVAL;
 306 #endif
 307 #ifndef CONFIG_TIME_NS
 308         if (flags & CLONE_NEWTIME)
 309                 return -EINVAL;
 310 #endif
 311
 312         return 0;
 313 }
 314
 315 static void put_nsset(struct nsset *nsset)
 316 {
 317         unsigned flags = nsset->flags;
 318
 319         if (flags & CLONE_NEWUSER)
 320                 put_cred(nsset_cred(nsset));
 321         /*
 322          * We only created a temporary copy if we attached to more than just
 323          * the mount namespace.
 324          */
 325         if (nsset->fs && (flags & CLONE_NEWNS) && (flags & ~CLONE_NEWNS))
 326                 free_fs_struct(nsset->fs);
 327         if (nsset->nsproxy)
 328                 free_nsproxy(nsset->nsproxy);
 329 }
 330
 331 static int prepare_nsset(unsigned flags, struct nsset *nsset)
 332 {
 333         struct task_struct *me = current;
 334
 335         nsset->nsproxy = create_new_namespaces(0, me, current_user_ns(), me->fs);
 336         if (IS_ERR(nsset->nsproxy))
 337                 return PTR_ERR(nsset->nsproxy);
 338
 339         if (flags & CLONE_NEWUSER)
 340                 nsset->cred = prepare_creds();
 341         else
 342                 nsset->cred = current_cred();
 343         if (!nsset->cred)
 344                 goto out;
 345
 346         /* Only create a temporary copy of fs_struct if we really need to. */
 347         if (flags == CLONE_NEWNS) {
 348                 nsset->fs = me->fs;
 349         } else if (flags & CLONE_NEWNS) {
 350                 nsset->fs = copy_fs_struct(me->fs);
 351                 if (!nsset->fs)
 352                         goto out;
 353         }
 354
 355         nsset->flags = flags;
 356         return 0;
 357
 358 out:
 359         put_nsset(nsset);
 360         return -ENOMEM;
 361 }
 362
 363 static inline int validate_ns(struct nsset *nsset, struct ns_common *ns)
 364 {
 365         return ns->ops->install(nsset, ns);
 366 }
 367
 368 /*
 369  * This is the inverse operation to unshare().
 370  * Ordering is equivalent to the standard ordering used everywhere else
 371  * during unshare and process creation. The switch to the new set of
 372  * namespaces occurs at the point of no return after installation of
 373  * all requested namespaces was successful in commit_nsset().
 374  */
 375 static int validate_nsset(struct nsset *nsset, struct pid *pid)
 376 {
 377         int ret = 0;
 378         unsigned flags = nsset->flags;
 379         struct user_namespace *user_ns = NULL;
 380         struct pid_namespace *pid_ns = NULL;
 381         struct nsproxy *nsp;
 382         struct task_struct *tsk;
 383
 384         /* Take a "snapshot" of the target task's namespaces. */
 385         rcu_read_lock();
 386         tsk = pid_task(pid, PIDTYPE_PID);
 387         if (!tsk) {
 388                 rcu_read_unlock();
 389                 return -ESRCH;
 390         }
 391
 392         if (!ptrace_may_access(tsk, PTRACE_MODE_READ_REALCREDS)) {
 393                 rcu_read_unlock();
 394                 return -EPERM;
 395         }
 396
 397         task_lock(tsk);
 398         nsp = tsk->nsproxy;
 399         if (nsp)
 400                 get_nsproxy(nsp);
 401         task_unlock(tsk);
 402         if (!nsp) {
 403                 rcu_read_unlock();
 404                 return -ESRCH;
 405         }
 406
 407 #ifdef CONFIG_PID_NS
 408         if (flags & CLONE_NEWPID) {
 409                 pid_ns = task_active_pid_ns(tsk);
 410                 if (unlikely(!pid_ns)) {
 411                         rcu_read_unlock();
 412                         ret = -ESRCH;
 413                         goto out;
 414                 }
 415                 get_pid_ns(pid_ns);
 416         }
 417 #endif
 418
 419 #ifdef CONFIG_USER_NS
 420         if (flags & CLONE_NEWUSER)
 421                 user_ns = get_user_ns(__task_cred(tsk)->user_ns);
 422 #endif
 423         rcu_read_unlock();
 424
 425         /*
 426          * Install requested namespaces. The caller will have
 427          * verified earlier that the requested namespaces are
 428          * supported on this kernel. We don't report errors here
 429          * if a namespace is requested that isn't supported.
 430          */
 431 #ifdef CONFIG_USER_NS
 432         if (flags & CLONE_NEWUSER) {
 433                 ret = validate_ns(nsset, &user_ns->ns);
 434                 if (ret)
 435                         goto out;
 436         }
 437 #endif
 438
 439         if (flags & CLONE_NEWNS) {
 440                 ret = validate_ns(nsset, from_mnt_ns(nsp->mnt_ns));
 441                 if (ret)
 442                         goto out;
 443         }
 444
 445 #ifdef CONFIG_UTS_NS
 446         if (flags & CLONE_NEWUTS) {
 447                 ret = validate_ns(nsset, &nsp->uts_ns->ns);
 448                 if (ret)
 449                         goto out;
 450         }
 451 #endif
 452
 453 #ifdef CONFIG_IPC_NS
 454         if (flags & CLONE_NEWIPC) {
 455                 ret = validate_ns(nsset, &nsp->ipc_ns->ns);
 456                 if (ret)
 457                         goto out;
 458         }
 459 #endif
 460
 461 #ifdef CONFIG_PID_NS
 462         if (flags & CLONE_NEWPID) {
 463                 ret = validate_ns(nsset, &pid_ns->ns);
 464                 if (ret)
 465                         goto out;
 466         }
 467 #endif
 468
 469 #ifdef CONFIG_CGROUPS
 470         if (flags & CLONE_NEWCGROUP) {
 471                 ret = validate_ns(nsset, &nsp->cgroup_ns->ns);
 472                 if (ret)
 473                         goto out;
 474         }
 475 #endif
 476
 477 #ifdef CONFIG_NET_NS
 478         if (flags & CLONE_NEWNET) {
 479                 ret = validate_ns(nsset, &nsp->net_ns->ns);
 480                 if (ret)
 481                         goto out;
 482         }
 483 #endif
 484
 485 #ifdef CONFIG_TIME_NS
 486         if (flags & CLONE_NEWTIME) {
 487                 ret = validate_ns(nsset, &nsp->time_ns->ns);
 488                 if (ret)
 489                         goto out;
 490         }
 491 #endif
 492
 493 out:
 494         if (pid_ns)
 495                 put_pid_ns(pid_ns);
 496         if (nsp)
 497                 put_nsproxy(nsp);
 498         put_user_ns(user_ns);
 499
 500         return ret;
 501 }
 502
 503 /*
 504  * This is the point of no return. There are just a few namespaces
 505  * that do some actual work here and it's sufficiently minimal that
 506  * a separate ns_common operation seems unnecessary for now.
 507  * Unshare is doing the same thing. If we'll end up needing to do
 508  * more in a given namespace or a helper here is ultimately not
 509  * exported anymore a simple commit handler for each namespace
 510  * should be added to ns_common.
 511  */
 512 static void commit_nsset(struct nsset *nsset)
 513 {
 514         unsigned flags = nsset->flags;
 515         struct task_struct *me = current;
 516
 517 #ifdef CONFIG_USER_NS
 518         if (flags & CLONE_NEWUSER) {
 519                 /* transfer ownership */
 520                 commit_creds(nsset_cred(nsset));
 521                 nsset->cred = NULL;
 522         }
 523 #endif
 524
 525         /* We only need to commit if we have used a temporary fs_struct. */
 526         if ((flags & CLONE_NEWNS) && (flags & ~CLONE_NEWNS)) {
 527                 set_fs_root(me->fs, &nsset->fs->root);
 528                 set_fs_pwd(me->fs, &nsset->fs->pwd);
 529         }
 530
 531 #ifdef CONFIG_IPC_NS
 532         if (flags & CLONE_NEWIPC)
 533                 exit_sem(me);
 534 #endif
 535
 536 #ifdef CONFIG_TIME_NS
 537         if (flags & CLONE_NEWTIME)
 538                 timens_commit(me, nsset->nsproxy->time_ns);
 539 #endif
 540
 541         /* transfer ownership */
 542         switch_task_namespaces(me, nsset->nsproxy);
 543         nsset->nsproxy = NULL;
 544 }
 545
 546 SYSCALL_DEFINE2(setns, int, fd, int, flags)
 547 {
 548         struct fd f = fdget(fd);
 549         struct ns_common *ns = NULL;
 550         struct nsset nsset = {};
 551         int err = 0;
 552
 553         if (!f.file)
 554                 return -EBADF;
 555
 556         if (proc_ns_file(f.file)) {
 557                 ns = get_proc_ns(file_inode(f.file));
 558                 if (flags && (ns->ops->type != flags))
 559                         err = -EINVAL;
 560                 flags = ns->ops->type;
 561         } else if (!IS_ERR(pidfd_pid(f.file))) {
 562                 err = check_setns_flags(flags);
 563         } else {
 564                 err = -EINVAL;
 565         }
 566         if (err)
 567                 goto out;
 568
 569         err = prepare_nsset(flags, &nsset);
 570         if (err)
 571                 goto out;
 572
 573         if (proc_ns_file(f.file))
 574                 err = validate_ns(&nsset, ns);
 575         else
 576                 err = validate_nsset(&nsset, f.file->private_data);
 577         if (!err) {
 578                 commit_nsset(&nsset);
 579                 perf_event_namespaces(current);
 580         }
 581         put_nsset(&nsset);
 582 out:
 583         fdput(f);
 584         return err;
 585 }
 586
 587 int __init nsproxy_cache_init(void)
 588 {
 589         nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC|SLAB_ACCOUNT);
 590         return 0;
 591 }