root/kernel/nsproxy.c

DEFINITIONS

1. create_nsproxy
2. create_new_namespaces
3. copy_namespaces
4. free_nsproxy
5. unshare_nsproxy_namespaces
6. switch_task_namespaces
7. exit_task_namespaces
8. SYSCALL_DEFINE2
9. nsproxy_cache_init

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