1 /* 2 * Copyright (C) 2006 IBM Corporation 3 * 4 * Author: Serge Hallyn <[email protected]> 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 <[email protected]> 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 = { 28 .count = ATOMIC_INIT(1), 29 .uts_ns = &init_uts_ns, 30 #if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC) 31 .ipc_ns = &init_ipc_ns, 32 #endif 33 .mnt_ns = NULL, 34 .pid_ns = &init_pid_ns, 35 #ifdef CONFIG_NET 36 .net_ns = &init_net, 37 #endif 38 }; 39 40 static inline struct nsproxy *create_nsproxy(void) 41 { 42 struct nsproxy *nsproxy; 43 44 nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL); 45 if (nsproxy) 46 atomic_set(&nsproxy->count, 1); 47 return nsproxy; 48 } 49 50 /* 51 * Create new nsproxy and all of its the associated namespaces. 52 * Return the newly created nsproxy. Do not attach this to the task, 53 * leave it to the caller to do proper locking and attach it to task. 54 */ 55 static struct nsproxy *create_new_namespaces(unsigned long flags, 56 struct task_struct *tsk, struct fs_struct *new_fs) 57 { 58 struct nsproxy *new_nsp; 59 int err; 60 61 new_nsp = create_nsproxy(); 62 if (!new_nsp) 63 return ERR_PTR(-ENOMEM); 64 65 new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, new_fs); 66 if (IS_ERR(new_nsp->mnt_ns)) { 67 err = PTR_ERR(new_nsp->mnt_ns); 68 goto out_ns; 69 } 70 71 new_nsp->uts_ns = copy_utsname(flags, tsk->nsproxy->uts_ns); 72 if (IS_ERR(new_nsp->uts_ns)) { 73 err = PTR_ERR(new_nsp->uts_ns); 74 goto out_uts; 75 } 76 77 new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns); 78 if (IS_ERR(new_nsp->ipc_ns)) { 79 err = PTR_ERR(new_nsp->ipc_ns); 80 goto out_ipc; 81 } 82 83 new_nsp->pid_ns = copy_pid_ns(flags, task_active_pid_ns(tsk)); 84 if (IS_ERR(new_nsp->pid_ns)) { 85 err = PTR_ERR(new_nsp->pid_ns); 86 goto out_pid; 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->pid_ns) 99 put_pid_ns(new_nsp->pid_ns); 100 out_pid: 101 if (new_nsp->ipc_ns) 102 put_ipc_ns(new_nsp->ipc_ns); 103 out_ipc: 104 if (new_nsp->uts_ns) 105 put_uts_ns(new_nsp->uts_ns); 106 out_uts: 107 if (new_nsp->mnt_ns) 108 put_mnt_ns(new_nsp->mnt_ns); 109 out_ns: 110 kmem_cache_free(nsproxy_cachep, new_nsp); 111 return ERR_PTR(err); 112 } 113 114 /* 115 * called from clone. This now handles copy for nsproxy and all 116 * namespaces therein. 117 */ 118 int copy_namespaces(unsigned long flags, struct task_struct *tsk) 119 { 120 struct nsproxy *old_ns = tsk->nsproxy; 121 struct nsproxy *new_ns; 122 int err = 0; 123 124 if (!old_ns) 125 return 0; 126 127 get_nsproxy(old_ns); 128 129 if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | 130 CLONE_NEWPID | CLONE_NEWNET))) 131 return 0; 132 133 if (!capable(CAP_SYS_ADMIN)) { 134 err = -EPERM; 135 goto out; 136 } 137 138 /* 139 * CLONE_NEWIPC must detach from the undolist: after switching 140 * to a new ipc namespace, the semaphore arrays from the old 141 * namespace are unreachable. In clone parlance, CLONE_SYSVSEM 142 * means share undolist with parent, so we must forbid using 143 * it along with CLONE_NEWIPC. 144 */ 145 if ((flags & CLONE_NEWIPC) && (flags & CLONE_SYSVSEM)) { 146 err = -EINVAL; 147 goto out; 148 } 149 150 new_ns = create_new_namespaces(flags, tsk, tsk->fs); 151 if (IS_ERR(new_ns)) { 152 err = PTR_ERR(new_ns); 153 goto out; 154 } 155 156 tsk->nsproxy = new_ns; 157 158 out: 159 put_nsproxy(old_ns); 160 return err; 161 } 162 163 void free_nsproxy(struct nsproxy *ns) 164 { 165 if (ns->mnt_ns) 166 put_mnt_ns(ns->mnt_ns); 167 if (ns->uts_ns) 168 put_uts_ns(ns->uts_ns); 169 if (ns->ipc_ns) 170 put_ipc_ns(ns->ipc_ns); 171 if (ns->pid_ns) 172 put_pid_ns(ns->pid_ns); 173 put_net(ns->net_ns); 174 kmem_cache_free(nsproxy_cachep, ns); 175 } 176 177 /* 178 * Called from unshare. Unshare all the namespaces part of nsproxy. 179 * On success, returns the new nsproxy. 180 */ 181 int unshare_nsproxy_namespaces(unsigned long unshare_flags, 182 struct nsproxy **new_nsp, struct fs_struct *new_fs) 183 { 184 int err = 0; 185 186 if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | 187 CLONE_NEWNET))) 188 return 0; 189 190 if (!capable(CAP_SYS_ADMIN)) 191 return -EPERM; 192 193 *new_nsp = create_new_namespaces(unshare_flags, current, 194 new_fs ? new_fs : current->fs); 195 if (IS_ERR(*new_nsp)) { 196 err = PTR_ERR(*new_nsp); 197 goto out; 198 } 199 200 err = ns_cgroup_clone(current, task_pid(current)); 201 if (err) 202 put_nsproxy(*new_nsp); 203 204 out: 205 return err; 206 } 207 208 void switch_task_namespaces(struct task_struct *p, struct nsproxy *new) 209 { 210 struct nsproxy *ns; 211 212 might_sleep(); 213 214 ns = p->nsproxy; 215 216 rcu_assign_pointer(p->nsproxy, new); 217 218 if (ns && atomic_dec_and_test(&ns->count)) { 219 /* 220 * wait for others to get what they want from this nsproxy. 221 * 222 * cannot release this nsproxy via the call_rcu() since 223 * put_mnt_ns() will want to sleep 224 */ 225 synchronize_rcu(); 226 free_nsproxy(ns); 227 } 228 } 229 230 void exit_task_namespaces(struct task_struct *p) 231 { 232 switch_task_namespaces(p, NULL); 233 } 234 235 static int __init nsproxy_cache_init(void) 236 { 237 nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC); 238 return 0; 239 } 240 241 module_init(nsproxy_cache_init); 242