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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
73
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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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90
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94
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
132static int user_epoll_alloc(struct user_struct *up)
133{
134#ifdef CONFIG_EPOLL
135 return percpu_counter_init(&up->epoll_watches, 0, GFP_KERNEL);
136#else
137 return 0;
138#endif
139}
140
141static void user_epoll_free(struct user_struct *up)
142{
143#ifdef CONFIG_EPOLL
144 percpu_counter_destroy(&up->epoll_watches);
145#endif
146}
147
148
149
150
151
152static void free_user(struct user_struct *up, unsigned long flags)
153 __releases(&uidhash_lock)
154{
155 uid_hash_remove(up);
156 spin_unlock_irqrestore(&uidhash_lock, flags);
157 user_epoll_free(up);
158 kmem_cache_free(uid_cachep, up);
159}
160
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165
166
167struct user_struct *find_user(kuid_t uid)
168{
169 struct user_struct *ret;
170 unsigned long flags;
171
172 spin_lock_irqsave(&uidhash_lock, flags);
173 ret = uid_hash_find(uid, uidhashentry(uid));
174 spin_unlock_irqrestore(&uidhash_lock, flags);
175 return ret;
176}
177
178void free_uid(struct user_struct *up)
179{
180 unsigned long flags;
181
182 if (!up)
183 return;
184
185 if (refcount_dec_and_lock_irqsave(&up->__count, &uidhash_lock, &flags))
186 free_user(up, flags);
187}
188
189struct user_struct *alloc_uid(kuid_t uid)
190{
191 struct hlist_head *hashent = uidhashentry(uid);
192 struct user_struct *up, *new;
193
194 spin_lock_irq(&uidhash_lock);
195 up = uid_hash_find(uid, hashent);
196 spin_unlock_irq(&uidhash_lock);
197
198 if (!up) {
199 new = kmem_cache_zalloc(uid_cachep, GFP_KERNEL);
200 if (!new)
201 return NULL;
202
203 new->uid = uid;
204 refcount_set(&new->__count, 1);
205 if (user_epoll_alloc(new)) {
206 kmem_cache_free(uid_cachep, new);
207 return NULL;
208 }
209 ratelimit_state_init(&new->ratelimit, HZ, 100);
210 ratelimit_set_flags(&new->ratelimit, RATELIMIT_MSG_ON_RELEASE);
211
212
213
214
215
216 spin_lock_irq(&uidhash_lock);
217 up = uid_hash_find(uid, hashent);
218 if (up) {
219 user_epoll_free(new);
220 kmem_cache_free(uid_cachep, new);
221 } else {
222 uid_hash_insert(new, hashent);
223 up = new;
224 }
225 spin_unlock_irq(&uidhash_lock);
226 }
227
228 return up;
229}
230
231static int __init uid_cache_init(void)
232{
233 int n;
234
235 uid_cachep = kmem_cache_create("uid_cache", sizeof(struct user_struct),
236 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
237
238 for(n = 0; n < UIDHASH_SZ; ++n)
239 INIT_HLIST_HEAD(uidhash_table + n);
240
241 if (user_epoll_alloc(&root_user))
242 panic("root_user epoll percpu counter alloc failed");
243
244
245 spin_lock_irq(&uidhash_lock);
246 uid_hash_insert(&root_user, uidhashentry(GLOBAL_ROOT_UID));
247 spin_unlock_irq(&uidhash_lock);
248
249 return 0;
250}
251subsys_initcall(uid_cache_init);
252