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