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 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 25 static struct kmem_cache *nsproxy_cachep; 26 27 struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy); 28 29 /* 30 * creates a copy of "orig" with refcount 1. 31 */ 32 static inline struct nsproxy *clone_nsproxy(struct nsproxy *orig) 33 { 34 struct nsproxy *ns; 35 36 ns = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL); 37 if (ns) { 38 memcpy(ns, orig, sizeof(struct nsproxy)); 39 atomic_set(&ns->count, 1); 40 } 41 return ns; 42 } 43 44 /* 45 * Create new nsproxy and all of its the associated namespaces. 46 * Return the newly created nsproxy. Do not attach this to the task, 47 * leave it to the caller to do proper locking and attach it to task. 48 */ 49 static struct nsproxy *create_new_namespaces(unsigned long flags, 50 struct task_struct *tsk, struct fs_struct *new_fs) 51 { 52 struct nsproxy *new_nsp; 53 int err; 54 55 new_nsp = clone_nsproxy(tsk->nsproxy); 56 if (!new_nsp) 57 return ERR_PTR(-ENOMEM); 58 59 new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, new_fs); 60 if (IS_ERR(new_nsp->mnt_ns)) { 61 err = PTR_ERR(new_nsp->mnt_ns); 62 goto out_ns; 63 } 64 65 new_nsp->uts_ns = copy_utsname(flags, tsk->nsproxy->uts_ns); 66 if (IS_ERR(new_nsp->uts_ns)) { 67 err = PTR_ERR(new_nsp->uts_ns); 68 goto out_uts; 69 } 70 71 new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns); 72 if (IS_ERR(new_nsp->ipc_ns)) { 73 err = PTR_ERR(new_nsp->ipc_ns); 74 goto out_ipc; 75 } 76 77 new_nsp->pid_ns = copy_pid_ns(flags, task_active_pid_ns(tsk)); 78 if (IS_ERR(new_nsp->pid_ns)) { 79 err = PTR_ERR(new_nsp->pid_ns); 80 goto out_pid; 81 } 82 83 new_nsp->user_ns = copy_user_ns(flags, tsk->nsproxy->user_ns); 84 if (IS_ERR(new_nsp->user_ns)) { 85 err = PTR_ERR(new_nsp->user_ns); 86 goto out_user; 87 } 88 89 new_nsp->net_ns = copy_net_ns(flags, tsk->nsproxy->net_ns); 90 if (IS_ERR(new_nsp->net_ns)) { 91 err = PTR_ERR(new_nsp->net_ns); 92 goto out_net; 93 } 94 95 return new_nsp; 96 97 out_net: 98 if (new_nsp->user_ns) 99 put_user_ns(new_nsp->user_ns); 100 out_user: 101 if (new_nsp->pid_ns) 102 put_pid_ns(new_nsp->pid_ns); 103 out_pid: 104 if (new_nsp->ipc_ns) 105 put_ipc_ns(new_nsp->ipc_ns); 106 out_ipc: 107 if (new_nsp->uts_ns) 108 put_uts_ns(new_nsp->uts_ns); 109 out_uts: 110 if (new_nsp->mnt_ns) 111 put_mnt_ns(new_nsp->mnt_ns); 112 out_ns: 113 kmem_cache_free(nsproxy_cachep, new_nsp); 114 return ERR_PTR(err); 115 } 116 117 /* 118 * called from clone. This now handles copy for nsproxy and all 119 * namespaces therein. 120 */ 121 int copy_namespaces(unsigned long flags, struct task_struct *tsk) 122 { 123 struct nsproxy *old_ns = tsk->nsproxy; 124 struct nsproxy *new_ns; 125 int err = 0; 126 127 if (!old_ns) 128 return 0; 129 130 get_nsproxy(old_ns); 131 132 if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | 133 CLONE_NEWUSER | CLONE_NEWPID | CLONE_NEWNET))) 134 return 0; 135 136 if (!capable(CAP_SYS_ADMIN)) { 137 err = -EPERM; 138 goto out; 139 } 140 141 /* 142 * CLONE_NEWIPC must detach from the undolist: after switching 143 * to a new ipc namespace, the semaphore arrays from the old 144 * namespace are unreachable. In clone parlance, CLONE_SYSVSEM 145 * means share undolist with parent, so we must forbid using 146 * it along with CLONE_NEWIPC. 147 */ 148 if ((flags & CLONE_NEWIPC) && (flags & CLONE_SYSVSEM)) { 149 err = -EINVAL; 150 goto out; 151 } 152 153 new_ns = create_new_namespaces(flags, tsk, tsk->fs); 154 if (IS_ERR(new_ns)) { 155 err = PTR_ERR(new_ns); 156 goto out; 157 } 158 159 tsk->nsproxy = new_ns; 160 161 out: 162 put_nsproxy(old_ns); 163 return err; 164 } 165 166 void free_nsproxy(struct nsproxy *ns) 167 { 168 if (ns->mnt_ns) 169 put_mnt_ns(ns->mnt_ns); 170 if (ns->uts_ns) 171 put_uts_ns(ns->uts_ns); 172 if (ns->ipc_ns) 173 put_ipc_ns(ns->ipc_ns); 174 if (ns->pid_ns) 175 put_pid_ns(ns->pid_ns); 176 if (ns->user_ns) 177 put_user_ns(ns->user_ns); 178 put_net(ns->net_ns); 179 kmem_cache_free(nsproxy_cachep, ns); 180 } 181 182 /* 183 * Called from unshare. Unshare all the namespaces part of nsproxy. 184 * On success, returns the new nsproxy. 185 */ 186 int unshare_nsproxy_namespaces(unsigned long unshare_flags, 187 struct nsproxy **new_nsp, struct fs_struct *new_fs) 188 { 189 int err = 0; 190 191 if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | 192 CLONE_NEWUSER | CLONE_NEWNET))) 193 return 0; 194 195 if (!capable(CAP_SYS_ADMIN)) 196 return -EPERM; 197 198 *new_nsp = create_new_namespaces(unshare_flags, current, 199 new_fs ? new_fs : current->fs); 200 if (IS_ERR(*new_nsp)) { 201 err = PTR_ERR(*new_nsp); 202 goto out; 203 } 204 205 err = ns_cgroup_clone(current, task_pid(current)); 206 if (err) 207 put_nsproxy(*new_nsp); 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 ns = p->nsproxy; 220 221 rcu_assign_pointer(p->nsproxy, new); 222 223 if (ns && atomic_dec_and_test(&ns->count)) { 224 /* 225 * wait for others to get what they want from this nsproxy. 226 * 227 * cannot release this nsproxy via the call_rcu() since 228 * put_mnt_ns() will want to sleep 229 */ 230 synchronize_rcu(); 231 free_nsproxy(ns); 232 } 233 } 234 235 void exit_task_namespaces(struct task_struct *p) 236 { 237 switch_task_namespaces(p, NULL); 238 } 239 240 static int __init nsproxy_cache_init(void) 241 { 242 nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC); 243 return 0; 244 } 245 246 module_init(nsproxy_cache_init); 247