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_ns.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_for_children = &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 user_namespace *user_ns, 61 struct fs_struct *new_fs) 62 { 63 struct nsproxy *new_nsp; 64 int err; 65 66 new_nsp = create_nsproxy(); 67 if (!new_nsp) 68 return ERR_PTR(-ENOMEM); 69 70 new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, user_ns, new_fs); 71 if (IS_ERR(new_nsp->mnt_ns)) { 72 err = PTR_ERR(new_nsp->mnt_ns); 73 goto out_ns; 74 } 75 76 new_nsp->uts_ns = copy_utsname(flags, user_ns, tsk->nsproxy->uts_ns); 77 if (IS_ERR(new_nsp->uts_ns)) { 78 err = PTR_ERR(new_nsp->uts_ns); 79 goto out_uts; 80 } 81 82 new_nsp->ipc_ns = copy_ipcs(flags, user_ns, tsk->nsproxy->ipc_ns); 83 if (IS_ERR(new_nsp->ipc_ns)) { 84 err = PTR_ERR(new_nsp->ipc_ns); 85 goto out_ipc; 86 } 87 88 new_nsp->pid_ns_for_children = 89 copy_pid_ns(flags, user_ns, tsk->nsproxy->pid_ns_for_children); 90 if (IS_ERR(new_nsp->pid_ns_for_children)) { 91 err = PTR_ERR(new_nsp->pid_ns_for_children); 92 goto out_pid; 93 } 94 95 new_nsp->net_ns = copy_net_ns(flags, user_ns, tsk->nsproxy->net_ns); 96 if (IS_ERR(new_nsp->net_ns)) { 97 err = PTR_ERR(new_nsp->net_ns); 98 goto out_net; 99 } 100 101 return new_nsp; 102 103 out_net: 104 if (new_nsp->pid_ns_for_children) 105 put_pid_ns(new_nsp->pid_ns_for_children); 106 out_pid: 107 if (new_nsp->ipc_ns) 108 put_ipc_ns(new_nsp->ipc_ns); 109 out_ipc: 110 if (new_nsp->uts_ns) 111 put_uts_ns(new_nsp->uts_ns); 112 out_uts: 113 if (new_nsp->mnt_ns) 114 put_mnt_ns(new_nsp->mnt_ns); 115 out_ns: 116 kmem_cache_free(nsproxy_cachep, new_nsp); 117 return ERR_PTR(err); 118 } 119 120 /* 121 * called from clone. This now handles copy for nsproxy and all 122 * namespaces therein. 123 */ 124 int copy_namespaces(unsigned long flags, struct task_struct *tsk) 125 { 126 struct nsproxy *old_ns = tsk->nsproxy; 127 struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns); 128 struct nsproxy *new_ns; 129 130 if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | 131 CLONE_NEWPID | CLONE_NEWNET)))) { 132 get_nsproxy(old_ns); 133 return 0; 134 } 135 136 if (!ns_capable(user_ns, CAP_SYS_ADMIN)) 137 return -EPERM; 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 | CLONE_SYSVSEM)) == 147 (CLONE_NEWIPC | CLONE_SYSVSEM)) 148 return -EINVAL; 149 150 new_ns = create_new_namespaces(flags, tsk, user_ns, tsk->fs); 151 if (IS_ERR(new_ns)) 152 return PTR_ERR(new_ns); 153 154 tsk->nsproxy = new_ns; 155 return 0; 156 } 157 158 void free_nsproxy(struct nsproxy *ns) 159 { 160 if (ns->mnt_ns) 161 put_mnt_ns(ns->mnt_ns); 162 if (ns->uts_ns) 163 put_uts_ns(ns->uts_ns); 164 if (ns->ipc_ns) 165 put_ipc_ns(ns->ipc_ns); 166 if (ns->pid_ns_for_children) 167 put_pid_ns(ns->pid_ns_for_children); 168 put_net(ns->net_ns); 169 kmem_cache_free(nsproxy_cachep, ns); 170 } 171 172 /* 173 * Called from unshare. Unshare all the namespaces part of nsproxy. 174 * On success, returns the new nsproxy. 175 */ 176 int unshare_nsproxy_namespaces(unsigned long unshare_flags, 177 struct nsproxy **new_nsp, struct cred *new_cred, struct fs_struct *new_fs) 178 { 179 struct user_namespace *user_ns; 180 int err = 0; 181 182 if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | 183 CLONE_NEWNET | CLONE_NEWPID))) 184 return 0; 185 186 user_ns = new_cred ? new_cred->user_ns : current_user_ns(); 187 if (!ns_capable(user_ns, CAP_SYS_ADMIN)) 188 return -EPERM; 189 190 *new_nsp = create_new_namespaces(unshare_flags, current, user_ns, 191 new_fs ? new_fs : current->fs); 192 if (IS_ERR(*new_nsp)) { 193 err = PTR_ERR(*new_nsp); 194 goto out; 195 } 196 197 out: 198 return err; 199 } 200 201 void switch_task_namespaces(struct task_struct *p, struct nsproxy *new) 202 { 203 struct nsproxy *ns; 204 205 might_sleep(); 206 207 ns = p->nsproxy; 208 209 rcu_assign_pointer(p->nsproxy, new); 210 211 if (ns && atomic_dec_and_test(&ns->count)) { 212 /* 213 * wait for others to get what they want from this nsproxy. 214 * 215 * cannot release this nsproxy via the call_rcu() since 216 * put_mnt_ns() will want to sleep 217 */ 218 synchronize_rcu(); 219 free_nsproxy(ns); 220 } 221 } 222 223 void exit_task_namespaces(struct task_struct *p) 224 { 225 switch_task_namespaces(p, NULL); 226 } 227 228 SYSCALL_DEFINE2(setns, int, fd, int, nstype) 229 { 230 const struct proc_ns_operations *ops; 231 struct task_struct *tsk = current; 232 struct nsproxy *new_nsproxy; 233 struct proc_ns *ei; 234 struct file *file; 235 int err; 236 237 file = proc_ns_fget(fd); 238 if (IS_ERR(file)) 239 return PTR_ERR(file); 240 241 err = -EINVAL; 242 ei = get_proc_ns(file_inode(file)); 243 ops = ei->ns_ops; 244 if (nstype && (ops->type != nstype)) 245 goto out; 246 247 new_nsproxy = create_new_namespaces(0, tsk, current_user_ns(), tsk->fs); 248 if (IS_ERR(new_nsproxy)) { 249 err = PTR_ERR(new_nsproxy); 250 goto out; 251 } 252 253 err = ops->install(new_nsproxy, ei->ns); 254 if (err) { 255 free_nsproxy(new_nsproxy); 256 goto out; 257 } 258 switch_task_namespaces(tsk, new_nsproxy); 259 out: 260 fput(file); 261 return err; 262 } 263 264 int __init nsproxy_cache_init(void) 265 { 266 nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC); 267 return 0; 268 } 269