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/export.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 #include <linux/proc_fs.h> 26 #include <linux/file.h> 27 #include <linux/syscalls.h> 28 29 static struct kmem_cache *nsproxy_cachep; 30 31 struct nsproxy init_nsproxy = { 32 .count = ATOMIC_INIT(1), 33 .uts_ns = &init_uts_ns, 34 #if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC) 35 .ipc_ns = &init_ipc_ns, 36 #endif 37 .mnt_ns = NULL, 38 .pid_ns = &init_pid_ns, 39 #ifdef CONFIG_NET 40 .net_ns = &init_net, 41 #endif 42 }; 43 44 static inline struct nsproxy *create_nsproxy(void) 45 { 46 struct nsproxy *nsproxy; 47 48 nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL); 49 if (nsproxy) 50 atomic_set(&nsproxy->count, 1); 51 return nsproxy; 52 } 53 54 /* 55 * Create new nsproxy and all of its the associated namespaces. 56 * Return the newly created nsproxy. Do not attach this to the task, 57 * leave it to the caller to do proper locking and attach it to task. 58 */ 59 static struct nsproxy *create_new_namespaces(unsigned long flags, 60 struct task_struct *tsk, struct fs_struct *new_fs) 61 { 62 struct nsproxy *new_nsp; 63 int err; 64 65 new_nsp = create_nsproxy(); 66 if (!new_nsp) 67 return ERR_PTR(-ENOMEM); 68 69 new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, new_fs); 70 if (IS_ERR(new_nsp->mnt_ns)) { 71 err = PTR_ERR(new_nsp->mnt_ns); 72 goto out_ns; 73 } 74 75 new_nsp->uts_ns = copy_utsname(flags, tsk); 76 if (IS_ERR(new_nsp->uts_ns)) { 77 err = PTR_ERR(new_nsp->uts_ns); 78 goto out_uts; 79 } 80 81 new_nsp->ipc_ns = copy_ipcs(flags, tsk); 82 if (IS_ERR(new_nsp->ipc_ns)) { 83 err = PTR_ERR(new_nsp->ipc_ns); 84 goto out_ipc; 85 } 86 87 new_nsp->pid_ns = copy_pid_ns(flags, task_active_pid_ns(tsk)); 88 if (IS_ERR(new_nsp->pid_ns)) { 89 err = PTR_ERR(new_nsp->pid_ns); 90 goto out_pid; 91 } 92 93 new_nsp->net_ns = copy_net_ns(flags, tsk->nsproxy->net_ns); 94 if (IS_ERR(new_nsp->net_ns)) { 95 err = PTR_ERR(new_nsp->net_ns); 96 goto out_net; 97 } 98 99 return new_nsp; 100 101 out_net: 102 if (new_nsp->pid_ns) 103 put_pid_ns(new_nsp->pid_ns); 104 out_pid: 105 if (new_nsp->ipc_ns) 106 put_ipc_ns(new_nsp->ipc_ns); 107 out_ipc: 108 if (new_nsp->uts_ns) 109 put_uts_ns(new_nsp->uts_ns); 110 out_uts: 111 if (new_nsp->mnt_ns) 112 put_mnt_ns(new_nsp->mnt_ns); 113 out_ns: 114 kmem_cache_free(nsproxy_cachep, new_nsp); 115 return ERR_PTR(err); 116 } 117 118 /* 119 * called from clone. This now handles copy for nsproxy and all 120 * namespaces therein. 121 */ 122 int copy_namespaces(unsigned long flags, struct task_struct *tsk) 123 { 124 struct nsproxy *old_ns = tsk->nsproxy; 125 struct nsproxy *new_ns; 126 int err = 0; 127 128 if (!old_ns) 129 return 0; 130 131 get_nsproxy(old_ns); 132 133 if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | 134 CLONE_NEWPID | CLONE_NEWNET))) 135 return 0; 136 137 if (!capable(CAP_SYS_ADMIN)) { 138 err = -EPERM; 139 goto out; 140 } 141 142 /* 143 * CLONE_NEWIPC must detach from the undolist: after switching 144 * to a new ipc namespace, the semaphore arrays from the old 145 * namespace are unreachable. In clone parlance, CLONE_SYSVSEM 146 * means share undolist with parent, so we must forbid using 147 * it along with CLONE_NEWIPC. 148 */ 149 if ((flags & CLONE_NEWIPC) && (flags & CLONE_SYSVSEM)) { 150 err = -EINVAL; 151 goto out; 152 } 153 154 new_ns = create_new_namespaces(flags, tsk, tsk->fs); 155 if (IS_ERR(new_ns)) { 156 err = PTR_ERR(new_ns); 157 goto out; 158 } 159 160 tsk->nsproxy = new_ns; 161 162 out: 163 put_nsproxy(old_ns); 164 return err; 165 } 166 167 void free_nsproxy(struct nsproxy *ns) 168 { 169 if (ns->mnt_ns) 170 put_mnt_ns(ns->mnt_ns); 171 if (ns->uts_ns) 172 put_uts_ns(ns->uts_ns); 173 if (ns->ipc_ns) 174 put_ipc_ns(ns->ipc_ns); 175 if (ns->pid_ns) 176 put_pid_ns(ns->pid_ns); 177 put_net(ns->net_ns); 178 kmem_cache_free(nsproxy_cachep, ns); 179 } 180 181 /* 182 * Called from unshare. Unshare all the namespaces part of nsproxy. 183 * On success, returns the new nsproxy. 184 */ 185 int unshare_nsproxy_namespaces(unsigned long unshare_flags, 186 struct nsproxy **new_nsp, struct fs_struct *new_fs) 187 { 188 int err = 0; 189 190 if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | 191 CLONE_NEWNET))) 192 return 0; 193 194 if (!capable(CAP_SYS_ADMIN)) 195 return -EPERM; 196 197 *new_nsp = create_new_namespaces(unshare_flags, current, 198 new_fs ? new_fs : current->fs); 199 if (IS_ERR(*new_nsp)) { 200 err = PTR_ERR(*new_nsp); 201 goto out; 202 } 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 SYSCALL_DEFINE2(setns, int, fd, int, nstype) 236 { 237 const struct proc_ns_operations *ops; 238 struct task_struct *tsk = current; 239 struct nsproxy *new_nsproxy; 240 struct proc_inode *ei; 241 struct file *file; 242 int err; 243 244 if (!capable(CAP_SYS_ADMIN)) 245 return -EPERM; 246 247 file = proc_ns_fget(fd); 248 if (IS_ERR(file)) 249 return PTR_ERR(file); 250 251 err = -EINVAL; 252 ei = PROC_I(file->f_dentry->d_inode); 253 ops = ei->ns_ops; 254 if (nstype && (ops->type != nstype)) 255 goto out; 256 257 new_nsproxy = create_new_namespaces(0, tsk, tsk->fs); 258 if (IS_ERR(new_nsproxy)) { 259 err = PTR_ERR(new_nsproxy); 260 goto out; 261 } 262 263 err = ops->install(new_nsproxy, ei->ns); 264 if (err) { 265 free_nsproxy(new_nsproxy); 266 goto out; 267 } 268 switch_task_namespaces(tsk, new_nsproxy); 269 out: 270 fput(file); 271 return err; 272 } 273 274 int __init nsproxy_cache_init(void) 275 { 276 nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC); 277 return 0; 278 } 279