nsproxy.c 5.3 KB

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  1. /*
  2. * Copyright (C) 2006 IBM Corporation
  3. *
  4. * Author: Serge Hallyn <serue@us.ibm.com>
  5. *
  6. * This program is free software; you can redistribute it and/or
  7. * modify it under the terms of the GNU General Public License as
  8. * published by the Free Software Foundation, version 2 of the
  9. * License.
  10. *
  11. * Jun 2006 - namespaces support
  12. * OpenVZ, SWsoft Inc.
  13. * Pavel Emelianov <xemul@openvz.org>
  14. */
  15. #include <linux/slab.h>
  16. #include <linux/module.h>
  17. #include <linux/nsproxy.h>
  18. #include <linux/init_task.h>
  19. #include <linux/mnt_namespace.h>
  20. #include <linux/utsname.h>
  21. #include <linux/pid_namespace.h>
  22. #include <net/net_namespace.h>
  23. #include <linux/ipc_namespace.h>
  24. static struct kmem_cache *nsproxy_cachep;
  25. struct nsproxy init_nsproxy = {
  26. .count = ATOMIC_INIT(1),
  27. .uts_ns = &init_uts_ns,
  28. #if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC)
  29. .ipc_ns = &init_ipc_ns,
  30. #endif
  31. .mnt_ns = NULL,
  32. .pid_ns = &init_pid_ns,
  33. #ifdef CONFIG_NET
  34. .net_ns = &init_net,
  35. #endif
  36. };
  37. static inline struct nsproxy *create_nsproxy(void)
  38. {
  39. struct nsproxy *nsproxy;
  40. nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL);
  41. if (nsproxy)
  42. atomic_set(&nsproxy->count, 1);
  43. return nsproxy;
  44. }
  45. /*
  46. * Create new nsproxy and all of its the associated namespaces.
  47. * Return the newly created nsproxy. Do not attach this to the task,
  48. * leave it to the caller to do proper locking and attach it to task.
  49. */
  50. static struct nsproxy *create_new_namespaces(unsigned long flags,
  51. struct task_struct *tsk, struct fs_struct *new_fs)
  52. {
  53. struct nsproxy *new_nsp;
  54. int err;
  55. new_nsp = create_nsproxy();
  56. if (!new_nsp)
  57. return ERR_PTR(-ENOMEM);
  58. new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, new_fs);
  59. if (IS_ERR(new_nsp->mnt_ns)) {
  60. err = PTR_ERR(new_nsp->mnt_ns);
  61. goto out_ns;
  62. }
  63. new_nsp->uts_ns = copy_utsname(flags, tsk->nsproxy->uts_ns);
  64. if (IS_ERR(new_nsp->uts_ns)) {
  65. err = PTR_ERR(new_nsp->uts_ns);
  66. goto out_uts;
  67. }
  68. new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns);
  69. if (IS_ERR(new_nsp->ipc_ns)) {
  70. err = PTR_ERR(new_nsp->ipc_ns);
  71. goto out_ipc;
  72. }
  73. new_nsp->pid_ns = copy_pid_ns(flags, task_active_pid_ns(tsk));
  74. if (IS_ERR(new_nsp->pid_ns)) {
  75. err = PTR_ERR(new_nsp->pid_ns);
  76. goto out_pid;
  77. }
  78. new_nsp->net_ns = copy_net_ns(flags, tsk->nsproxy->net_ns);
  79. if (IS_ERR(new_nsp->net_ns)) {
  80. err = PTR_ERR(new_nsp->net_ns);
  81. goto out_net;
  82. }
  83. return new_nsp;
  84. out_net:
  85. if (new_nsp->pid_ns)
  86. put_pid_ns(new_nsp->pid_ns);
  87. out_pid:
  88. if (new_nsp->ipc_ns)
  89. put_ipc_ns(new_nsp->ipc_ns);
  90. out_ipc:
  91. if (new_nsp->uts_ns)
  92. put_uts_ns(new_nsp->uts_ns);
  93. out_uts:
  94. if (new_nsp->mnt_ns)
  95. put_mnt_ns(new_nsp->mnt_ns);
  96. out_ns:
  97. kmem_cache_free(nsproxy_cachep, new_nsp);
  98. return ERR_PTR(err);
  99. }
  100. /*
  101. * called from clone. This now handles copy for nsproxy and all
  102. * namespaces therein.
  103. */
  104. int copy_namespaces(unsigned long flags, struct task_struct *tsk)
  105. {
  106. struct nsproxy *old_ns = tsk->nsproxy;
  107. struct nsproxy *new_ns;
  108. int err = 0;
  109. if (!old_ns)
  110. return 0;
  111. get_nsproxy(old_ns);
  112. if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
  113. CLONE_NEWPID | CLONE_NEWNET)))
  114. return 0;
  115. if (!capable(CAP_SYS_ADMIN)) {
  116. err = -EPERM;
  117. goto out;
  118. }
  119. /*
  120. * CLONE_NEWIPC must detach from the undolist: after switching
  121. * to a new ipc namespace, the semaphore arrays from the old
  122. * namespace are unreachable. In clone parlance, CLONE_SYSVSEM
  123. * means share undolist with parent, so we must forbid using
  124. * it along with CLONE_NEWIPC.
  125. */
  126. if ((flags & CLONE_NEWIPC) && (flags & CLONE_SYSVSEM)) {
  127. err = -EINVAL;
  128. goto out;
  129. }
  130. new_ns = create_new_namespaces(flags, tsk, tsk->fs);
  131. if (IS_ERR(new_ns)) {
  132. err = PTR_ERR(new_ns);
  133. goto out;
  134. }
  135. tsk->nsproxy = new_ns;
  136. out:
  137. put_nsproxy(old_ns);
  138. return err;
  139. }
  140. void free_nsproxy(struct nsproxy *ns)
  141. {
  142. if (ns->mnt_ns)
  143. put_mnt_ns(ns->mnt_ns);
  144. if (ns->uts_ns)
  145. put_uts_ns(ns->uts_ns);
  146. if (ns->ipc_ns)
  147. put_ipc_ns(ns->ipc_ns);
  148. if (ns->pid_ns)
  149. put_pid_ns(ns->pid_ns);
  150. put_net(ns->net_ns);
  151. kmem_cache_free(nsproxy_cachep, ns);
  152. }
  153. /*
  154. * Called from unshare. Unshare all the namespaces part of nsproxy.
  155. * On success, returns the new nsproxy.
  156. */
  157. int unshare_nsproxy_namespaces(unsigned long unshare_flags,
  158. struct nsproxy **new_nsp, struct fs_struct *new_fs)
  159. {
  160. int err = 0;
  161. if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
  162. CLONE_NEWNET)))
  163. return 0;
  164. if (!capable(CAP_SYS_ADMIN))
  165. return -EPERM;
  166. *new_nsp = create_new_namespaces(unshare_flags, current,
  167. new_fs ? new_fs : current->fs);
  168. if (IS_ERR(*new_nsp)) {
  169. err = PTR_ERR(*new_nsp);
  170. goto out;
  171. }
  172. err = ns_cgroup_clone(current, task_pid(current));
  173. if (err)
  174. put_nsproxy(*new_nsp);
  175. out:
  176. return err;
  177. }
  178. void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
  179. {
  180. struct nsproxy *ns;
  181. might_sleep();
  182. ns = p->nsproxy;
  183. rcu_assign_pointer(p->nsproxy, new);
  184. if (ns && atomic_dec_and_test(&ns->count)) {
  185. /*
  186. * wait for others to get what they want from this nsproxy.
  187. *
  188. * cannot release this nsproxy via the call_rcu() since
  189. * put_mnt_ns() will want to sleep
  190. */
  191. synchronize_rcu();
  192. free_nsproxy(ns);
  193. }
  194. }
  195. void exit_task_namespaces(struct task_struct *p)
  196. {
  197. switch_task_namespaces(p, NULL);
  198. }
  199. static int __init nsproxy_cache_init(void)
  200. {
  201. nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
  202. return 0;
  203. }
  204. module_init(nsproxy_cache_init);