| 1 | |
| 2 | * Copyright (C) 2004 IBM Corporation
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| 3 | *
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| 4 | * Author: Serge Hallyn <[email protected]>
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| 5 | *
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| 6 | * This program is free software; you can redistribute it and/or
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| 7 | * modify it under the terms of the GNU General Public License as
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| 8 | * published by the Free Software Foundation, version 2 of the
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| 9 | * License.
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| 10 |
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| 11 |
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| 12 | #include <linux/module.h>
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| 13 | #include <linux/uts.h>
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| 14 | #include <linux/utsname.h>
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| 15 | #include <linux/err.h>
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| 16 | #include <linux/slab.h>
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| 17 | #include <linux/user_namespace.h>
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| 18 | #include <linux/proc_fs.h>
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| 19 |
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| 20 | static struct uts_namespace *create_uts_ns(void)
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| 21 | {
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| 22 | struct uts_namespace *uts_ns;
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| 23 |
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| 24 | uts_ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL);
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| 25 | if (uts_ns)
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| 26 | kref_init(&uts_ns->kref);
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| 27 | return uts_ns;
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| 28 | }
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| 29 |
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| 30 | |
| 31 | * Clone a new ns copying an original utsname, setting refcount to 1
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| 32 | * @old_ns: namespace to clone
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| 33 | * Return NULL on error (failure to kmalloc), new ns otherwise
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| 34 |
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| 35 | static struct uts_namespace *clone_uts_ns(struct task_struct *tsk,
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| 36 | struct uts_namespace *old_ns)
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| 37 | {
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| 38 | struct uts_namespace *ns;
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| 39 |
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| 40 | ns = create_uts_ns();
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| 41 | if (!ns)
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| 42 | return ERR_PTR(-ENOMEM);
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| 43 |
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| 44 | down_read(&uts_sem);
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| 45 | memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
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| 46 | ns->user_ns = get_user_ns(task_cred_xxx(tsk, user)->user_ns);
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| 47 | up_read(&uts_sem);
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| 48 | return ns;
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| 49 | }
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| 50 |
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| 51 | |
| 52 | * Copy task tsk's utsname namespace, or clone it if flags
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| 53 | * specifies CLONE_NEWUTS. In latter case, changes to the
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| 54 | * utsname of this process won't be seen by parent, and vice
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| 55 | * versa.
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| 56 |
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| 57 | struct uts_namespace *copy_utsname(unsigned long flags,
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| 58 | struct task_struct *tsk)
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| 59 | {
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| 60 | struct uts_namespace *old_ns = tsk->nsproxy->uts_ns;
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| 61 | struct uts_namespace *new_ns;
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| 62 |
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| 63 | BUG_ON(!old_ns);
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| 64 | get_uts_ns(old_ns);
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| 65 |
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| 66 | if (!(flags & CLONE_NEWUTS))
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| 67 | return old_ns;
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| 68 |
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| 69 | new_ns = clone_uts_ns(tsk, old_ns);
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| 70 |
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| 71 | put_uts_ns(old_ns);
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| 72 | return new_ns;
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| 73 | }
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| 74 |
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| 75 | void free_uts_ns(struct kref *kref)
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| 76 | {
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| 77 | struct uts_namespace *ns;
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| 78 |
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| 79 | ns = container_of(kref, struct uts_namespace, kref);
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| 80 | put_user_ns(ns->user_ns);
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| 81 | kfree(ns);
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| 82 | }
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| 83 |
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| 84 | static void *utsns_get(struct task_struct *task)
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| 85 | {
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| 86 | struct uts_namespace *ns = NULL;
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| 87 | struct nsproxy *nsproxy;
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| 88 |
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| 89 | rcu_read_lock();
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| 90 | nsproxy = task_nsproxy(task);
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| 91 | if (nsproxy) {
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| 92 | ns = nsproxy->uts_ns;
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| 93 | get_uts_ns(ns);
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| 94 | }
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| 95 | rcu_read_unlock();
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| 96 |
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| 97 | return ns;
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| 98 | }
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| 99 |
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| 100 | static void utsns_put(void *ns)
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| 101 | {
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| 102 | put_uts_ns(ns);
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| 103 | }
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| 104 |
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| 105 | static int utsns_install(struct nsproxy *nsproxy, void *ns)
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| 106 | {
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| 107 | get_uts_ns(ns);
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| 108 | put_uts_ns(nsproxy->uts_ns);
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| 109 | nsproxy->uts_ns = ns;
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| 110 | return 0;
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| 111 | }
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| 112 |
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| 113 | const struct proc_ns_operations utsns_operations = {
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| 114 | .name = "uts",
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| 115 | .type = CLONE_NEWUTS,
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| 116 | .get = utsns_get,
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| 117 | .put = utsns_put,
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| 118 | .install = utsns_install,
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| 119 | };
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| 120 |
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