Commit | Line | Data |
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acce292c CLG |
1 | /* |
2 | * This program is free software; you can redistribute it and/or | |
3 | * modify it under the terms of the GNU General Public License as | |
4 | * published by the Free Software Foundation, version 2 of the | |
5 | * License. | |
6 | */ | |
7 | ||
9984de1a | 8 | #include <linux/export.h> |
acce292c | 9 | #include <linux/nsproxy.h> |
1aeb272c | 10 | #include <linux/slab.h> |
acce292c | 11 | #include <linux/user_namespace.h> |
5c1469de | 12 | #include <linux/highuid.h> |
18b6e041 | 13 | #include <linux/cred.h> |
973c5914 | 14 | #include <linux/securebits.h> |
acce292c | 15 | |
6164281a PE |
16 | static struct kmem_cache *user_ns_cachep __read_mostly; |
17 | ||
77ec739d | 18 | /* |
18b6e041 SH |
19 | * Create a new user namespace, deriving the creator from the user in the |
20 | * passed credentials, and replacing that user with the new root user for the | |
21 | * new namespace. | |
22 | * | |
23 | * This is called by copy_creds(), which will finish setting the target task's | |
24 | * credentials. | |
77ec739d | 25 | */ |
18b6e041 | 26 | int create_user_ns(struct cred *new) |
77ec739d | 27 | { |
0093ccb6 | 28 | struct user_namespace *ns, *parent_ns = new->user_ns; |
18b6e041 | 29 | struct user_struct *root_user; |
77ec739d | 30 | |
6164281a | 31 | ns = kmem_cache_alloc(user_ns_cachep, GFP_KERNEL); |
77ec739d | 32 | if (!ns) |
18b6e041 | 33 | return -ENOMEM; |
77ec739d SH |
34 | |
35 | kref_init(&ns->kref); | |
36 | ||
18b6e041 | 37 | /* Alloc new root user. */ |
7b44ab97 | 38 | root_user = alloc_uid(make_kuid(ns, 0)); |
18b6e041 | 39 | if (!root_user) { |
6164281a | 40 | kmem_cache_free(user_ns_cachep, ns); |
18b6e041 | 41 | return -ENOMEM; |
77ec739d SH |
42 | } |
43 | ||
18b6e041 | 44 | /* set the new root user in the credentials under preparation */ |
aeb3ae9d | 45 | ns->parent = parent_ns; |
18b6e041 SH |
46 | ns->creator = new->user; |
47 | new->user = root_user; | |
48 | new->uid = new->euid = new->suid = new->fsuid = 0; | |
49 | new->gid = new->egid = new->sgid = new->fsgid = 0; | |
50 | put_group_info(new->group_info); | |
51 | new->group_info = get_group_info(&init_groups); | |
973c5914 EB |
52 | /* Start with the same capabilities as init but useless for doing |
53 | * anything as the capabilities are bound to the new user namespace. | |
54 | */ | |
55 | new->securebits = SECUREBITS_DEFAULT; | |
56 | new->cap_inheritable = CAP_EMPTY_SET; | |
57 | new->cap_permitted = CAP_FULL_SET; | |
58 | new->cap_effective = CAP_FULL_SET; | |
59 | new->cap_bset = CAP_FULL_SET; | |
18b6e041 SH |
60 | #ifdef CONFIG_KEYS |
61 | key_put(new->request_key_auth); | |
62 | new->request_key_auth = NULL; | |
63 | #endif | |
64 | /* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */ | |
77ec739d | 65 | |
0093ccb6 EB |
66 | /* Leave the reference to our user_ns with the new cred */ |
67 | new->user_ns = ns; | |
68 | ||
18b6e041 | 69 | return 0; |
acce292c CLG |
70 | } |
71 | ||
51708366 DH |
72 | /* |
73 | * Deferred destructor for a user namespace. This is required because | |
74 | * free_user_ns() may be called with uidhash_lock held, but we need to call | |
75 | * back to free_uid() which will want to take the lock again. | |
76 | */ | |
77 | static void free_user_ns_work(struct work_struct *work) | |
acce292c | 78 | { |
aeb3ae9d | 79 | struct user_namespace *parent, *ns = |
51708366 | 80 | container_of(work, struct user_namespace, destroyer); |
aeb3ae9d | 81 | parent = ns->parent; |
18b6e041 | 82 | free_uid(ns->creator); |
6164281a | 83 | kmem_cache_free(user_ns_cachep, ns); |
aeb3ae9d | 84 | put_user_ns(parent); |
acce292c | 85 | } |
51708366 DH |
86 | |
87 | void free_user_ns(struct kref *kref) | |
88 | { | |
89 | struct user_namespace *ns = | |
90 | container_of(kref, struct user_namespace, kref); | |
91 | ||
92 | INIT_WORK(&ns->destroyer, free_user_ns_work); | |
93 | schedule_work(&ns->destroyer); | |
94 | } | |
6a3fd92e | 95 | EXPORT_SYMBOL(free_user_ns); |
5c1469de EB |
96 | |
97 | uid_t user_ns_map_uid(struct user_namespace *to, const struct cred *cred, uid_t uid) | |
98 | { | |
99 | struct user_namespace *tmp; | |
100 | ||
c4a4d603 | 101 | if (likely(to == cred->user_ns)) |
5c1469de EB |
102 | return uid; |
103 | ||
104 | ||
105 | /* Is cred->user the creator of the target user_ns | |
106 | * or the creator of one of it's parents? | |
107 | */ | |
aeb3ae9d | 108 | for ( tmp = to; tmp != &init_user_ns; tmp = tmp->parent ) { |
5c1469de EB |
109 | if (cred->user == tmp->creator) { |
110 | return (uid_t)0; | |
111 | } | |
112 | } | |
113 | ||
114 | /* No useful relationship so no mapping */ | |
115 | return overflowuid; | |
116 | } | |
117 | ||
118 | gid_t user_ns_map_gid(struct user_namespace *to, const struct cred *cred, gid_t gid) | |
119 | { | |
120 | struct user_namespace *tmp; | |
121 | ||
c4a4d603 | 122 | if (likely(to == cred->user_ns)) |
5c1469de EB |
123 | return gid; |
124 | ||
125 | /* Is cred->user the creator of the target user_ns | |
126 | * or the creator of one of it's parents? | |
127 | */ | |
aeb3ae9d | 128 | for ( tmp = to; tmp != &init_user_ns; tmp = tmp->parent ) { |
5c1469de EB |
129 | if (cred->user == tmp->creator) { |
130 | return (gid_t)0; | |
131 | } | |
132 | } | |
133 | ||
134 | /* No useful relationship so no mapping */ | |
135 | return overflowgid; | |
136 | } | |
6164281a PE |
137 | |
138 | static __init int user_namespaces_init(void) | |
139 | { | |
140 | user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC); | |
141 | return 0; | |
142 | } | |
143 | module_init(user_namespaces_init); |