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/slab.h> 17 #include <linux/module.h> 18 #include <linux/nsproxy.h> 19 #include <linux/init_task.h> 20 #include <linux/mnt_namespace.h> 21 #include <linux/utsname.h> 22 #include <linux/pid_namespace.h> 23 #include <net/net_namespace.h> 24 #include <linux/ipc_namespace.h> 25 26 static struct kmem_cache *nsproxy_cachep; 27 28 struct nsproxy init_nsproxy = { 29 .count = ATOMIC_INIT(1), 30 .uts_ns = &init_uts_ns, 31 #if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC) 32 .ipc_ns = &init_ipc_ns, 33 #endif 34 .mnt_ns = NULL, 35 .pid_ns = &init_pid_ns, 36 #ifdef CONFIG_NET 37 .net_ns = &init_net, 38 #endif 39 }; 40 41 static inline struct nsproxy *create_nsproxy(void) 42 { 43 struct nsproxy *nsproxy; 44 45 nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL); 46 if (nsproxy) 47 atomic_set(&nsproxy->count, 1); 48 return nsproxy; 49 } 50 51 /* 52 * Create new nsproxy and all of its the associated namespaces. 53 * Return the newly created nsproxy. Do not attach this to the task, 54 * leave it to the caller to do proper locking and attach it to task. 55 */ 56 static struct nsproxy *create_new_namespaces(unsigned long flags, 57 struct task_struct *tsk, struct fs_struct *new_fs) 58 { 59 struct nsproxy *new_nsp; 60 int err; 61 62 new_nsp = create_nsproxy(); 63 if (!new_nsp) 64 return ERR_PTR(-ENOMEM); 65 66 new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, new_fs); 67 if (IS_ERR(new_nsp->mnt_ns)) { 68 err = PTR_ERR(new_nsp->mnt_ns); 69 goto out_ns; 70 } 71 72 new_nsp->uts_ns = copy_utsname(flags, tsk); 73 if (IS_ERR(new_nsp->uts_ns)) { 74 err = PTR_ERR(new_nsp->uts_ns); 75 goto out_uts; 76 } 77 78 new_nsp->ipc_ns = copy_ipcs(flags, tsk); 79 if (IS_ERR(new_nsp->ipc_ns)) { 80 err = PTR_ERR(new_nsp->ipc_ns); 81 goto out_ipc; 82 } 83 84 new_nsp->pid_ns = copy_pid_ns(flags, task_active_pid_ns(tsk)); 85 if (IS_ERR(new_nsp->pid_ns)) { 86 err = PTR_ERR(new_nsp->pid_ns); 87 goto out_pid; 88 } 89 90 new_nsp->net_ns = copy_net_ns(flags, tsk->nsproxy->net_ns); 91 if (IS_ERR(new_nsp->net_ns)) { 92 err = PTR_ERR(new_nsp->net_ns); 93 goto out_net; 94 } 95 96 return new_nsp; 97 98 out_net: 99 if (new_nsp->pid_ns) 100 put_pid_ns(new_nsp->pid_ns); 101 out_pid: 102 if (new_nsp->ipc_ns) 103 put_ipc_ns(new_nsp->ipc_ns); 104 out_ipc: 105 if (new_nsp->uts_ns) 106 put_uts_ns(new_nsp->uts_ns); 107 out_uts: 108 if (new_nsp->mnt_ns) 109 put_mnt_ns(new_nsp->mnt_ns); 110 out_ns: 111 kmem_cache_free(nsproxy_cachep, new_nsp); 112 return ERR_PTR(err); 113 } 114 115 /* 116 * called from clone. This now handles copy for nsproxy and all 117 * namespaces therein. 118 */ 119 int copy_namespaces(unsigned long flags, struct task_struct *tsk) 120 { 121 struct nsproxy *old_ns = tsk->nsproxy; 122 struct nsproxy *new_ns; 123 int err = 0; 124 125 if (!old_ns) 126 return 0; 127 128 get_nsproxy(old_ns); 129 130 if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | 131 CLONE_NEWPID | CLONE_NEWNET))) 132 return 0; 133 134 if (!capable(CAP_SYS_ADMIN)) { 135 err = -EPERM; 136 goto out; 137 } 138 139 /* 140 * CLONE_NEWIPC must detach from the undolist: after switching 141 * to a new ipc namespace, the semaphore arrays from the old 142 * namespace are unreachable. In clone parlance, CLONE_SYSVSEM 143 * means share undolist with parent, so we must forbid using 144 * it along with CLONE_NEWIPC. 145 */ 146 if ((flags & CLONE_NEWIPC) && (flags & CLONE_SYSVSEM)) { 147 err = -EINVAL; 148 goto out; 149 } 150 151 new_ns = create_new_namespaces(flags, tsk, tsk->fs); 152 if (IS_ERR(new_ns)) { 153 err = PTR_ERR(new_ns); 154 goto out; 155 } 156 157 tsk->nsproxy = new_ns; 158 159 out: 160 put_nsproxy(old_ns); 161 return err; 162 } 163 164 void free_nsproxy(struct nsproxy *ns) 165 { 166 if (ns->mnt_ns) 167 put_mnt_ns(ns->mnt_ns); 168 if (ns->uts_ns) 169 put_uts_ns(ns->uts_ns); 170 if (ns->ipc_ns) 171 put_ipc_ns(ns->ipc_ns); 172 if (ns->pid_ns) 173 put_pid_ns(ns->pid_ns); 174 put_net(ns->net_ns); 175 kmem_cache_free(nsproxy_cachep, ns); 176 } 177 178 /* 179 * Called from unshare. Unshare all the namespaces part of nsproxy. 180 * On success, returns the new nsproxy. 181 */ 182 int unshare_nsproxy_namespaces(unsigned long unshare_flags, 183 struct nsproxy **new_nsp, struct fs_struct *new_fs) 184 { 185 int err = 0; 186 187 if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | 188 CLONE_NEWNET))) 189 return 0; 190 191 if (!capable(CAP_SYS_ADMIN)) 192 return -EPERM; 193 194 *new_nsp = create_new_namespaces(unshare_flags, current, 195 new_fs ? new_fs : current->fs); 196 if (IS_ERR(*new_nsp)) { 197 err = PTR_ERR(*new_nsp); 198 goto out; 199 } 200 201 err = ns_cgroup_clone(current, task_pid(current)); 202 if (err) 203 put_nsproxy(*new_nsp); 204 205 out: 206 return err; 207 } 208 209 void switch_task_namespaces(struct task_struct *p, struct nsproxy *new) 210 { 211 struct nsproxy *ns; 212 213 might_sleep(); 214 215 ns = p->nsproxy; 216 217 rcu_assign_pointer(p->nsproxy, new); 218 219 if (ns && atomic_dec_and_test(&ns->count)) { 220 /* 221 * wait for others to get what they want from this nsproxy. 222 * 223 * cannot release this nsproxy via the call_rcu() since 224 * put_mnt_ns() will want to sleep 225 */ 226 synchronize_rcu(); 227 free_nsproxy(ns); 228 } 229 } 230 231 void exit_task_namespaces(struct task_struct *p) 232 { 233 switch_task_namespaces(p, NULL); 234 } 235 236 static int __init nsproxy_cache_init(void) 237 { 238 nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC); 239 return 0; 240 } 241 242 module_init(nsproxy_cache_init); 243