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