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->net_ns = copy_net_ns(flags, tsk->nsproxy->net_ns); 84 if (IS_ERR(new_nsp->net_ns)) { 85 err = PTR_ERR(new_nsp->net_ns); 86 goto out_net; 87 } 88 89 return new_nsp; 90 91 out_net: 92 if (new_nsp->pid_ns) 93 put_pid_ns(new_nsp->pid_ns); 94 out_pid: 95 if (new_nsp->ipc_ns) 96 put_ipc_ns(new_nsp->ipc_ns); 97 out_ipc: 98 if (new_nsp->uts_ns) 99 put_uts_ns(new_nsp->uts_ns); 100 out_uts: 101 if (new_nsp->mnt_ns) 102 put_mnt_ns(new_nsp->mnt_ns); 103 out_ns: 104 kmem_cache_free(nsproxy_cachep, new_nsp); 105 return ERR_PTR(err); 106 } 107 108 /* 109 * called from clone. This now handles copy for nsproxy and all 110 * namespaces therein. 111 */ 112 int copy_namespaces(unsigned long flags, struct task_struct *tsk) 113 { 114 struct nsproxy *old_ns = tsk->nsproxy; 115 struct nsproxy *new_ns; 116 int err = 0; 117 118 if (!old_ns) 119 return 0; 120 121 get_nsproxy(old_ns); 122 123 if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | 124 CLONE_NEWPID | CLONE_NEWNET))) 125 return 0; 126 127 if (!capable(CAP_SYS_ADMIN)) { 128 err = -EPERM; 129 goto out; 130 } 131 132 /* 133 * CLONE_NEWIPC must detach from the undolist: after switching 134 * to a new ipc namespace, the semaphore arrays from the old 135 * namespace are unreachable. In clone parlance, CLONE_SYSVSEM 136 * means share undolist with parent, so we must forbid using 137 * it along with CLONE_NEWIPC. 138 */ 139 if ((flags & CLONE_NEWIPC) && (flags & CLONE_SYSVSEM)) { 140 err = -EINVAL; 141 goto out; 142 } 143 144 new_ns = create_new_namespaces(flags, tsk, tsk->fs); 145 if (IS_ERR(new_ns)) { 146 err = PTR_ERR(new_ns); 147 goto out; 148 } 149 150 tsk->nsproxy = new_ns; 151 152 out: 153 put_nsproxy(old_ns); 154 return err; 155 } 156 157 void free_nsproxy(struct nsproxy *ns) 158 { 159 if (ns->mnt_ns) 160 put_mnt_ns(ns->mnt_ns); 161 if (ns->uts_ns) 162 put_uts_ns(ns->uts_ns); 163 if (ns->ipc_ns) 164 put_ipc_ns(ns->ipc_ns); 165 if (ns->pid_ns) 166 put_pid_ns(ns->pid_ns); 167 put_net(ns->net_ns); 168 kmem_cache_free(nsproxy_cachep, ns); 169 } 170 171 /* 172 * Called from unshare. Unshare all the namespaces part of nsproxy. 173 * On success, returns the new nsproxy. 174 */ 175 int unshare_nsproxy_namespaces(unsigned long unshare_flags, 176 struct nsproxy **new_nsp, struct fs_struct *new_fs) 177 { 178 int err = 0; 179 180 if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | 181 CLONE_NEWNET))) 182 return 0; 183 184 if (!capable(CAP_SYS_ADMIN)) 185 return -EPERM; 186 187 *new_nsp = create_new_namespaces(unshare_flags, current, 188 new_fs ? new_fs : current->fs); 189 if (IS_ERR(*new_nsp)) { 190 err = PTR_ERR(*new_nsp); 191 goto out; 192 } 193 194 err = ns_cgroup_clone(current, task_pid(current)); 195 if (err) 196 put_nsproxy(*new_nsp); 197 198 out: 199 return err; 200 } 201 202 void switch_task_namespaces(struct task_struct *p, struct nsproxy *new) 203 { 204 struct nsproxy *ns; 205 206 might_sleep(); 207 208 ns = p->nsproxy; 209 210 rcu_assign_pointer(p->nsproxy, new); 211 212 if (ns && atomic_dec_and_test(&ns->count)) { 213 /* 214 * wait for others to get what they want from this nsproxy. 215 * 216 * cannot release this nsproxy via the call_rcu() since 217 * put_mnt_ns() will want to sleep 218 */ 219 synchronize_rcu(); 220 free_nsproxy(ns); 221 } 222 } 223 224 void exit_task_namespaces(struct task_struct *p) 225 { 226 switch_task_namespaces(p, NULL); 227 } 228 229 static int __init nsproxy_cache_init(void) 230 { 231 nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC); 232 return 0; 233 } 234 235 module_init(nsproxy_cache_init); 236