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12#include <linux/init.h>
13#include <linux/sched.h>
14#include <linux/slab.h>
15#include <linux/bitops.h>
16#include <linux/key.h>
17#include <linux/sched/user.h>
18#include <linux/interrupt.h>
19#include <linux/export.h>
20#include <linux/user_namespace.h>
21#include <linux/proc_ns.h>
22
23
24
25
26
27struct user_namespace init_user_ns = {
28 .uid_map = {
29 .nr_extents = 1,
30 {
31 .extent[0] = {
32 .first = 0,
33 .lower_first = 0,
34 .count = 4294967295U,
35 },
36 },
37 },
38 .gid_map = {
39 .nr_extents = 1,
40 {
41 .extent[0] = {
42 .first = 0,
43 .lower_first = 0,
44 .count = 4294967295U,
45 },
46 },
47 },
48 .projid_map = {
49 .nr_extents = 1,
50 {
51 .extent[0] = {
52 .first = 0,
53 .lower_first = 0,
54 .count = 4294967295U,
55 },
56 },
57 },
58 .ns.count = REFCOUNT_INIT(3),
59 .owner = GLOBAL_ROOT_UID,
60 .group = GLOBAL_ROOT_GID,
61 .ns.inum = PROC_USER_INIT_INO,
62#ifdef CONFIG_USER_NS
63 .ns.ops = &userns_operations,
64#endif
65 .flags = USERNS_INIT_FLAGS,
66#ifdef CONFIG_KEYS
67 .keyring_name_list = LIST_HEAD_INIT(init_user_ns.keyring_name_list),
68 .keyring_sem = __RWSEM_INITIALIZER(init_user_ns.keyring_sem),
69#endif
70};
71EXPORT_SYMBOL_GPL(init_user_ns);
72
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76
77
78#define UIDHASH_BITS (CONFIG_BASE_SMALL ? 3 : 7)
79#define UIDHASH_SZ (1 << UIDHASH_BITS)
80#define UIDHASH_MASK (UIDHASH_SZ - 1)
81#define __uidhashfn(uid) (((uid >> UIDHASH_BITS) + uid) & UIDHASH_MASK)
82#define uidhashentry(uid) (uidhash_table + __uidhashfn((__kuid_val(uid))))
83
84static struct kmem_cache *uid_cachep;
85static struct hlist_head uidhash_table[UIDHASH_SZ];
86
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95
96static DEFINE_SPINLOCK(uidhash_lock);
97
98
99struct user_struct root_user = {
100 .__count = REFCOUNT_INIT(1),
101 .uid = GLOBAL_ROOT_UID,
102 .ratelimit = RATELIMIT_STATE_INIT(root_user.ratelimit, 0, 0),
103};
104
105
106
107
108static void uid_hash_insert(struct user_struct *up, struct hlist_head *hashent)
109{
110 hlist_add_head(&up->uidhash_node, hashent);
111}
112
113static void uid_hash_remove(struct user_struct *up)
114{
115 hlist_del_init(&up->uidhash_node);
116}
117
118static struct user_struct *uid_hash_find(kuid_t uid, struct hlist_head *hashent)
119{
120 struct user_struct *user;
121
122 hlist_for_each_entry(user, hashent, uidhash_node) {
123 if (uid_eq(user->uid, uid)) {
124 refcount_inc(&user->__count);
125 return user;
126 }
127 }
128
129 return NULL;
130}
131
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133
134
135
136static void free_user(struct user_struct *up, unsigned long flags)
137 __releases(&uidhash_lock)
138{
139 uid_hash_remove(up);
140 spin_unlock_irqrestore(&uidhash_lock, flags);
141 kmem_cache_free(uid_cachep, up);
142}
143
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148
149
150struct user_struct *find_user(kuid_t uid)
151{
152 struct user_struct *ret;
153 unsigned long flags;
154
155 spin_lock_irqsave(&uidhash_lock, flags);
156 ret = uid_hash_find(uid, uidhashentry(uid));
157 spin_unlock_irqrestore(&uidhash_lock, flags);
158 return ret;
159}
160
161void free_uid(struct user_struct *up)
162{
163 unsigned long flags;
164
165 if (!up)
166 return;
167
168 if (refcount_dec_and_lock_irqsave(&up->__count, &uidhash_lock, &flags))
169 free_user(up, flags);
170}
171
172struct user_struct *alloc_uid(kuid_t uid)
173{
174 struct hlist_head *hashent = uidhashentry(uid);
175 struct user_struct *up, *new;
176
177 spin_lock_irq(&uidhash_lock);
178 up = uid_hash_find(uid, hashent);
179 spin_unlock_irq(&uidhash_lock);
180
181 if (!up) {
182 new = kmem_cache_zalloc(uid_cachep, GFP_KERNEL);
183 if (!new)
184 return NULL;
185
186 new->uid = uid;
187 refcount_set(&new->__count, 1);
188 ratelimit_state_init(&new->ratelimit, HZ, 100);
189 ratelimit_set_flags(&new->ratelimit, RATELIMIT_MSG_ON_RELEASE);
190
191
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193
194
195 spin_lock_irq(&uidhash_lock);
196 up = uid_hash_find(uid, hashent);
197 if (up) {
198 kmem_cache_free(uid_cachep, new);
199 } else {
200 uid_hash_insert(new, hashent);
201 up = new;
202 }
203 spin_unlock_irq(&uidhash_lock);
204 }
205
206 return up;
207}
208
209static int __init uid_cache_init(void)
210{
211 int n;
212
213 uid_cachep = kmem_cache_create("uid_cache", sizeof(struct user_struct),
214 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
215
216 for(n = 0; n < UIDHASH_SZ; ++n)
217 INIT_HLIST_HEAD(uidhash_table + n);
218
219
220 spin_lock_irq(&uidhash_lock);
221 uid_hash_insert(&root_user, uidhashentry(GLOBAL_ROOT_UID));
222 spin_unlock_irq(&uidhash_lock);
223
224 return 0;
225}
226subsys_initcall(uid_cache_init);
227