linux/kernel/nsproxy.c
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   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
  29static struct kmem_cache *nsproxy_cachep;
  30
  31struct 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
  44static 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 */
  59static 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
 103out_net:
 104        if (new_nsp->pid_ns_for_children)
 105                put_pid_ns(new_nsp->pid_ns_for_children);
 106out_pid:
 107        if (new_nsp->ipc_ns)
 108                put_ipc_ns(new_nsp->ipc_ns);
 109out_ipc:
 110        if (new_nsp->uts_ns)
 111                put_uts_ns(new_nsp->uts_ns);
 112out_uts:
 113        if (new_nsp->mnt_ns)
 114                put_mnt_ns(new_nsp->mnt_ns);
 115out_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 */
 124int 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        int err = 0;
 130
 131        if (!old_ns)
 132                return 0;
 133
 134        get_nsproxy(old_ns);
 135
 136        if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 137                                CLONE_NEWPID | CLONE_NEWNET)))
 138                return 0;
 139
 140        if (!ns_capable(user_ns, CAP_SYS_ADMIN)) {
 141                err = -EPERM;
 142                goto out;
 143        }
 144
 145        /*
 146         * CLONE_NEWIPC must detach from the undolist: after switching
 147         * to a new ipc namespace, the semaphore arrays from the old
 148         * namespace are unreachable.  In clone parlance, CLONE_SYSVSEM
 149         * means share undolist with parent, so we must forbid using
 150         * it along with CLONE_NEWIPC.
 151         */
 152        if ((flags & CLONE_NEWIPC) && (flags & CLONE_SYSVSEM)) {
 153                err = -EINVAL;
 154                goto out;
 155        }
 156
 157        new_ns = create_new_namespaces(flags, tsk, user_ns, tsk->fs);
 158        if (IS_ERR(new_ns)) {
 159                err = PTR_ERR(new_ns);
 160                goto out;
 161        }
 162
 163        tsk->nsproxy = new_ns;
 164
 165out:
 166        put_nsproxy(old_ns);
 167        return err;
 168}
 169
 170void free_nsproxy(struct nsproxy *ns)
 171{
 172        if (ns->mnt_ns)
 173                put_mnt_ns(ns->mnt_ns);
 174        if (ns->uts_ns)
 175                put_uts_ns(ns->uts_ns);
 176        if (ns->ipc_ns)
 177                put_ipc_ns(ns->ipc_ns);
 178        if (ns->pid_ns_for_children)
 179                put_pid_ns(ns->pid_ns_for_children);
 180        put_net(ns->net_ns);
 181        kmem_cache_free(nsproxy_cachep, ns);
 182}
 183
 184/*
 185 * Called from unshare. Unshare all the namespaces part of nsproxy.
 186 * On success, returns the new nsproxy.
 187 */
 188int unshare_nsproxy_namespaces(unsigned long unshare_flags,
 189        struct nsproxy **new_nsp, struct cred *new_cred, struct fs_struct *new_fs)
 190{
 191        struct user_namespace *user_ns;
 192        int err = 0;
 193
 194        if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
 195                               CLONE_NEWNET | CLONE_NEWPID)))
 196                return 0;
 197
 198        user_ns = new_cred ? new_cred->user_ns : current_user_ns();
 199        if (!ns_capable(user_ns, CAP_SYS_ADMIN))
 200                return -EPERM;
 201
 202        *new_nsp = create_new_namespaces(unshare_flags, current, user_ns,
 203                                         new_fs ? new_fs : current->fs);
 204        if (IS_ERR(*new_nsp)) {
 205                err = PTR_ERR(*new_nsp);
 206                goto out;
 207        }
 208
 209out:
 210        return err;
 211}
 212
 213void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
 214{
 215        struct nsproxy *ns;
 216
 217        might_sleep();
 218
 219        ns = p->nsproxy;
 220
 221        rcu_assign_pointer(p->nsproxy, new);
 222
 223        if (ns && atomic_dec_and_test(&ns->count)) {
 224                /*
 225                 * wait for others to get what they want from this nsproxy.
 226                 *
 227                 * cannot release this nsproxy via the call_rcu() since
 228                 * put_mnt_ns() will want to sleep
 229                 */
 230                synchronize_rcu();
 231                free_nsproxy(ns);
 232        }
 233}
 234
 235void exit_task_namespaces(struct task_struct *p)
 236{
 237        switch_task_namespaces(p, NULL);
 238}
 239
 240SYSCALL_DEFINE2(setns, int, fd, int, nstype)
 241{
 242        const struct proc_ns_operations *ops;
 243        struct task_struct *tsk = current;
 244        struct nsproxy *new_nsproxy;
 245        struct proc_ns *ei;
 246        struct file *file;
 247        int err;
 248
 249        file = proc_ns_fget(fd);
 250        if (IS_ERR(file))
 251                return PTR_ERR(file);
 252
 253        err = -EINVAL;
 254        ei = get_proc_ns(file_inode(file));
 255        ops = ei->ns_ops;
 256        if (nstype && (ops->type != nstype))
 257                goto out;
 258
 259        new_nsproxy = create_new_namespaces(0, tsk, current_user_ns(), tsk->fs);
 260        if (IS_ERR(new_nsproxy)) {
 261                err = PTR_ERR(new_nsproxy);
 262                goto out;
 263        }
 264
 265        err = ops->install(new_nsproxy, ei->ns);
 266        if (err) {
 267                free_nsproxy(new_nsproxy);
 268                goto out;
 269        }
 270        switch_task_namespaces(tsk, new_nsproxy);
 271out:
 272        fput(file);
 273        return err;
 274}
 275
 276int __init nsproxy_cache_init(void)
 277{
 278        nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
 279        return 0;
 280}
 281
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