| 1 | /* |
| 2 | * Copyright (C) 2004 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 | |
| 12 | #include <linux/export.h> |
| 13 | #include <linux/uts.h> |
| 14 | #include <linux/utsname.h> |
| 15 | #include <linux/err.h> |
| 16 | #include <linux/slab.h> |
| 17 | #include <linux/user_namespace.h> |
| 18 | #include <linux/proc_ns.h> |
| 19 | |
| 20 | static struct uts_namespace *create_uts_ns(void) |
| 21 | { |
| 22 | struct uts_namespace *uts_ns; |
| 23 | |
| 24 | uts_ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL); |
| 25 | if (uts_ns) |
| 26 | kref_init(&uts_ns->kref); |
| 27 | return uts_ns; |
| 28 | } |
| 29 | |
| 30 | /* |
| 31 | * Clone a new ns copying an original utsname, setting refcount to 1 |
| 32 | * @old_ns: namespace to clone |
| 33 | * Return ERR_PTR(-ENOMEM) on error (failure to kmalloc), new ns otherwise |
| 34 | */ |
| 35 | static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns, |
| 36 | struct uts_namespace *old_ns) |
| 37 | { |
| 38 | struct uts_namespace *ns; |
| 39 | int err; |
| 40 | |
| 41 | ns = create_uts_ns(); |
| 42 | if (!ns) |
| 43 | return ERR_PTR(-ENOMEM); |
| 44 | |
| 45 | err = ns_alloc_inum(&ns->ns); |
| 46 | if (err) { |
| 47 | kfree(ns); |
| 48 | return ERR_PTR(err); |
| 49 | } |
| 50 | |
| 51 | ns->ns.ops = &utsns_operations; |
| 52 | |
| 53 | down_read(&uts_sem); |
| 54 | memcpy(&ns->name, &old_ns->name, sizeof(ns->name)); |
| 55 | ns->user_ns = get_user_ns(user_ns); |
| 56 | up_read(&uts_sem); |
| 57 | return ns; |
| 58 | } |
| 59 | |
| 60 | /* |
| 61 | * Copy task tsk's utsname namespace, or clone it if flags |
| 62 | * specifies CLONE_NEWUTS. In latter case, changes to the |
| 63 | * utsname of this process won't be seen by parent, and vice |
| 64 | * versa. |
| 65 | */ |
| 66 | struct uts_namespace *copy_utsname(unsigned long flags, |
| 67 | struct user_namespace *user_ns, struct uts_namespace *old_ns) |
| 68 | { |
| 69 | struct uts_namespace *new_ns; |
| 70 | |
| 71 | BUG_ON(!old_ns); |
| 72 | get_uts_ns(old_ns); |
| 73 | |
| 74 | if (!(flags & CLONE_NEWUTS)) |
| 75 | return old_ns; |
| 76 | |
| 77 | new_ns = clone_uts_ns(user_ns, old_ns); |
| 78 | |
| 79 | put_uts_ns(old_ns); |
| 80 | return new_ns; |
| 81 | } |
| 82 | |
| 83 | void free_uts_ns(struct kref *kref) |
| 84 | { |
| 85 | struct uts_namespace *ns; |
| 86 | |
| 87 | ns = container_of(kref, struct uts_namespace, kref); |
| 88 | put_user_ns(ns->user_ns); |
| 89 | ns_free_inum(&ns->ns); |
| 90 | kfree(ns); |
| 91 | } |
| 92 | |
| 93 | static inline struct uts_namespace *to_uts_ns(struct ns_common *ns) |
| 94 | { |
| 95 | return container_of(ns, struct uts_namespace, ns); |
| 96 | } |
| 97 | |
| 98 | static struct ns_common *utsns_get(struct task_struct *task) |
| 99 | { |
| 100 | struct uts_namespace *ns = NULL; |
| 101 | struct nsproxy *nsproxy; |
| 102 | |
| 103 | task_lock(task); |
| 104 | nsproxy = task->nsproxy; |
| 105 | if (nsproxy) { |
| 106 | ns = nsproxy->uts_ns; |
| 107 | get_uts_ns(ns); |
| 108 | } |
| 109 | task_unlock(task); |
| 110 | |
| 111 | return ns ? &ns->ns : NULL; |
| 112 | } |
| 113 | |
| 114 | static void utsns_put(struct ns_common *ns) |
| 115 | { |
| 116 | put_uts_ns(to_uts_ns(ns)); |
| 117 | } |
| 118 | |
| 119 | static int utsns_install(struct nsproxy *nsproxy, struct ns_common *new) |
| 120 | { |
| 121 | struct uts_namespace *ns = to_uts_ns(new); |
| 122 | |
| 123 | if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) || |
| 124 | !ns_capable(current_user_ns(), CAP_SYS_ADMIN)) |
| 125 | return -EPERM; |
| 126 | |
| 127 | get_uts_ns(ns); |
| 128 | put_uts_ns(nsproxy->uts_ns); |
| 129 | nsproxy->uts_ns = ns; |
| 130 | return 0; |
| 131 | } |
| 132 | |
| 133 | const struct proc_ns_operations utsns_operations = { |
| 134 | .name = "uts", |
| 135 | .type = CLONE_NEWUTS, |
| 136 | .get = utsns_get, |
| 137 | .put = utsns_put, |
| 138 | .install = utsns_install, |
| 139 | }; |