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/proc_ns.h>
  23 #include <linux/file.h>
  24 #include <linux/syscalls.h>
  25 #include <linux/cgroup.h>
  26 #include <linux/perf_event.h>
  27
  28 static struct kmem_cache *nsproxy_cachep;
  29
  30 struct nsproxy init_nsproxy = {
  31         .count                  = ATOMIC_INIT(1),
  32         .uts_ns                 = &init_uts_ns,
  33 #if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC)
  34         .ipc_ns                 = &init_ipc_ns,
  35 #endif
  36         .mnt_ns                 = NULL,
  37         .pid_ns_for_children    = &init_pid_ns,
  38 #ifdef CONFIG_NET
  39         .net_ns                 = &init_net,
  40 #endif
  41 #ifdef CONFIG_CGROUPS
  42         .cgroup_ns              = &init_cgroup_ns,
  43 #endif
  44 #ifdef CONFIG_TIME_NS
  45         .time_ns                = &init_time_ns,
  46         .time_ns_for_children   = &init_time_ns,
  47 #endif
  48 };
  49
  50 static inline struct nsproxy *create_nsproxy(void)
  51 {
  52         struct nsproxy *nsproxy;
  53
  54         nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL);
  55         if (nsproxy)
  56                 atomic_set(&nsproxy->count, 1);
  57         return nsproxy;
  58 }
  59
  60 /*
  61  * Create new nsproxy and all of its the associated namespaces.
  62  * Return the newly created nsproxy.  Do not attach this to the task,
  63  * leave it to the caller to do proper locking and attach it to task.
  64  */
  65 static struct nsproxy *create_new_namespaces(unsigned long flags,
  66         struct task_struct *tsk, struct user_namespace *user_ns,
  67         struct fs_struct *new_fs)
  68 {
  69         struct nsproxy *new_nsp;
  70         int err;
  71
  72         new_nsp = create_nsproxy();
  73         if (!new_nsp)
  74                 return ERR_PTR(-ENOMEM);
  75
  76         new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, user_ns, new_fs);
  77         if (IS_ERR(new_nsp->mnt_ns)) {
  78                 err = PTR_ERR(new_nsp->mnt_ns);
  79                 goto out_ns;
  80         }
  81
  82         new_nsp->uts_ns = copy_utsname(flags, user_ns, tsk->nsproxy->uts_ns);
  83         if (IS_ERR(new_nsp->uts_ns)) {
  84                 err = PTR_ERR(new_nsp->uts_ns);
  85                 goto out_uts;
  86         }
  87
  88         new_nsp->ipc_ns = copy_ipcs(flags, user_ns, tsk->nsproxy->ipc_ns);
  89         if (IS_ERR(new_nsp->ipc_ns)) {
  90                 err = PTR_ERR(new_nsp->ipc_ns);
  91                 goto out_ipc;
  92         }
  93
  94         new_nsp->pid_ns_for_children =
  95                 copy_pid_ns(flags, user_ns, tsk->nsproxy->pid_ns_for_children);
  96         if (IS_ERR(new_nsp->pid_ns_for_children)) {
  97                 err = PTR_ERR(new_nsp->pid_ns_for_children);
  98                 goto out_pid;
  99         }
 100
 101         new_nsp->cgroup_ns = copy_cgroup_ns(flags, user_ns,
 102                                             tsk->nsproxy->cgroup_ns);
 103         if (IS_ERR(new_nsp->cgroup_ns)) {
 104                 err = PTR_ERR(new_nsp->cgroup_ns);
 105                 goto out_cgroup;
 106         }
 107
 108         new_nsp->net_ns = copy_net_ns(flags, user_ns, tsk->nsproxy->net_ns);
 109         if (IS_ERR(new_nsp->net_ns)) {
 110                 err = PTR_ERR(new_nsp->net_ns);
 111                 goto out_net;
 112         }
 113
 114         new_nsp->time_ns_for_children = copy_time_ns(flags, user_ns,
 115                                         tsk->nsproxy->time_ns_for_children);
 116         if (IS_ERR(new_nsp->time_ns_for_children)) {
 117                 err = PTR_ERR(new_nsp->time_ns_for_children);
 118                 goto out_time;
 119         }
 120         new_nsp->time_ns = get_time_ns(tsk->nsproxy->time_ns);
 121
 122         return new_nsp;
 123
 124 out_time:
 125         put_net(new_nsp->net_ns);
 126 out_net:
 127         put_cgroup_ns(new_nsp->cgroup_ns);
 128 out_cgroup:
 129         if (new_nsp->pid_ns_for_children)
 130                 put_pid_ns(new_nsp->pid_ns_for_children);
 131 out_pid:
 132         if (new_nsp->ipc_ns)
 133                 put_ipc_ns(new_nsp->ipc_ns);
 134 out_ipc:
 135         if (new_nsp->uts_ns)
 136                 put_uts_ns(new_nsp->uts_ns);
 137 out_uts:
 138         if (new_nsp->mnt_ns)
 139                 put_mnt_ns(new_nsp->mnt_ns);
 140 out_ns:
 141         kmem_cache_free(nsproxy_cachep, new_nsp);
 142         return ERR_PTR(err);
 143 }
 144
 145 /*
 146  * called from clone.  This now handles copy for nsproxy and all
 147  * namespaces therein.
 148  */
 149 int copy_namespaces(unsigned long flags, struct task_struct *tsk)
 150 {
 151         struct nsproxy *old_ns = tsk->nsproxy;
 152         struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns);
 153         struct nsproxy *new_ns;
 154         int ret;
 155
 156         if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 157                               CLONE_NEWPID | CLONE_NEWNET |
 158                               CLONE_NEWCGROUP | CLONE_NEWTIME)))) {
 159                 if (likely(old_ns->time_ns_for_children == old_ns->time_ns)) {
 160                         get_nsproxy(old_ns);
 161                         return 0;
 162                 }
 163         } else if (!ns_capable(user_ns, CAP_SYS_ADMIN))
 164                 return -EPERM;
 165
 166         /*
 167          * CLONE_NEWIPC must detach from the undolist: after switching
 168          * to a new ipc namespace, the semaphore arrays from the old
 169          * namespace are unreachable.  In clone parlance, CLONE_SYSVSEM
 170          * means share undolist with parent, so we must forbid using
 171          * it along with CLONE_NEWIPC.
 172          */
 173         if ((flags & (CLONE_NEWIPC | CLONE_SYSVSEM)) ==
 174                 (CLONE_NEWIPC | CLONE_SYSVSEM))
 175                 return -EINVAL;
 176
 177         new_ns = create_new_namespaces(flags, tsk, user_ns, tsk->fs);
 178         if (IS_ERR(new_ns))
 179                 return  PTR_ERR(new_ns);
 180
 181         ret = timens_on_fork(new_ns, tsk);
 182         if (ret) {
 183                 free_nsproxy(new_ns);
 184                 return ret;
 185         }
 186
 187         tsk->nsproxy = new_ns;
 188         return 0;
 189 }
 190
 191 void free_nsproxy(struct nsproxy *ns)
 192 {
 193         if (ns->mnt_ns)
 194                 put_mnt_ns(ns->mnt_ns);
 195         if (ns->uts_ns)
 196                 put_uts_ns(ns->uts_ns);
 197         if (ns->ipc_ns)
 198                 put_ipc_ns(ns->ipc_ns);
 199         if (ns->pid_ns_for_children)
 200                 put_pid_ns(ns->pid_ns_for_children);
 201         if (ns->time_ns)
 202                 put_time_ns(ns->time_ns);
 203         if (ns->time_ns_for_children)
 204                 put_time_ns(ns->time_ns_for_children);
 205         put_cgroup_ns(ns->cgroup_ns);
 206         put_net(ns->net_ns);
 207         kmem_cache_free(nsproxy_cachep, ns);
 208 }
 209
 210 /*
 211  * Called from unshare. Unshare all the namespaces part of nsproxy.
 212  * On success, returns the new nsproxy.
 213  */
 214 int unshare_nsproxy_namespaces(unsigned long unshare_flags,
 215         struct nsproxy **new_nsp, struct cred *new_cred, struct fs_struct *new_fs)
 216 {
 217         struct user_namespace *user_ns;
 218         int err = 0;
 219
 220         if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 221                                CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP |
 222                                CLONE_NEWTIME)))
 223                 return 0;
 224
 225         user_ns = new_cred ? new_cred->user_ns : current_user_ns();
 226         if (!ns_capable(user_ns, CAP_SYS_ADMIN))
 227                 return -EPERM;
 228
 229         *new_nsp = create_new_namespaces(unshare_flags, current, user_ns,
 230                                          new_fs ? new_fs : current->fs);
 231         if (IS_ERR(*new_nsp)) {
 232                 err = PTR_ERR(*new_nsp);
 233                 goto out;
 234         }
 235
 236 out:
 237         return err;
 238 }
 239
 240 void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
 241 {
 242         struct nsproxy *ns;
 243
 244         might_sleep();
 245
 246         task_lock(p);
 247         ns = p->nsproxy;
 248         p->nsproxy = new;
 249         task_unlock(p);
 250
 251         if (ns && atomic_dec_and_test(&ns->count))
 252                 free_nsproxy(ns);
 253 }
 254
 255 void exit_task_namespaces(struct task_struct *p)
 256 {
 257         switch_task_namespaces(p, NULL);
 258 }
 259
 260 SYSCALL_DEFINE2(setns, int, fd, int, nstype)
 261 {
 262         struct task_struct *tsk = current;
 263         struct nsproxy *new_nsproxy;
 264         struct file *file;
 265         struct ns_common *ns;
 266         int err;
 267
 268         file = proc_ns_fget(fd);
 269         if (IS_ERR(file))
 270                 return PTR_ERR(file);
 271
 272         err = -EINVAL;
 273         ns = get_proc_ns(file_inode(file));
 274         if (nstype && (ns->ops->type != nstype))
 275                 goto out;
 276
 277         new_nsproxy = create_new_namespaces(0, tsk, current_user_ns(), tsk->fs);
 278         if (IS_ERR(new_nsproxy)) {
 279                 err = PTR_ERR(new_nsproxy);
 280                 goto out;
 281         }
 282
 283         err = ns->ops->install(new_nsproxy, ns);
 284         if (err) {
 285                 free_nsproxy(new_nsproxy);
 286                 goto out;
 287         }
 288         switch_task_namespaces(tsk, new_nsproxy);
 289
 290         perf_event_namespaces(tsk);
 291 out:
 292         fput(file);
 293         return err;
 294 }
 295
 296 int __init nsproxy_cache_init(void)
 297 {
 298         nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
 299         return 0;
 300 }