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11#include <linux/init.h>
12#include <linux/sched.h>
13#include <linux/slab.h>
14#include <linux/bitops.h>
15#include <linux/key.h>
16#include <linux/interrupt.h>
17#include <linux/export.h>
18#include <linux/user_namespace.h>
19#include <linux/proc_ns.h>
20
21
22
23
24
25struct user_namespace init_user_ns = {
26 .uid_map = {
27 .nr_extents = 1,
28 .extent[0] = {
29 .first = 0,
30 .lower_first = 0,
31 .count = 4294967295U,
32 },
33 },
34 .gid_map = {
35 .nr_extents = 1,
36 .extent[0] = {
37 .first = 0,
38 .lower_first = 0,
39 .count = 4294967295U,
40 },
41 },
42 .projid_map = {
43 .nr_extents = 1,
44 .extent[0] = {
45 .first = 0,
46 .lower_first = 0,
47 .count = 4294967295U,
48 },
49 },
50 .count = ATOMIC_INIT(3),
51 .owner = GLOBAL_ROOT_UID,
52 .group = GLOBAL_ROOT_GID,
53 .proc_inum = PROC_USER_INIT_INO,
54 .may_mount_sysfs = true,
55 .may_mount_proc = true,
56};
57EXPORT_SYMBOL_GPL(init_user_ns);
58
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61
62
63
64#define UIDHASH_BITS (CONFIG_BASE_SMALL ? 3 : 7)
65#define UIDHASH_SZ (1 << UIDHASH_BITS)
66#define UIDHASH_MASK (UIDHASH_SZ - 1)
67#define __uidhashfn(uid) (((uid >> UIDHASH_BITS) + uid) & UIDHASH_MASK)
68#define uidhashentry(uid) (uidhash_table + __uidhashfn((__kuid_val(uid))))
69
70static struct kmem_cache *uid_cachep;
71struct hlist_head uidhash_table[UIDHASH_SZ];
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81
82static DEFINE_SPINLOCK(uidhash_lock);
83
84
85struct user_struct root_user = {
86 .__count = ATOMIC_INIT(1),
87 .processes = ATOMIC_INIT(1),
88 .files = ATOMIC_INIT(0),
89 .sigpending = ATOMIC_INIT(0),
90 .locked_shm = 0,
91 .uid = GLOBAL_ROOT_UID,
92};
93
94
95
96
97static void uid_hash_insert(struct user_struct *up, struct hlist_head *hashent)
98{
99 hlist_add_head(&up->uidhash_node, hashent);
100}
101
102static void uid_hash_remove(struct user_struct *up)
103{
104 hlist_del_init(&up->uidhash_node);
105}
106
107static struct user_struct *uid_hash_find(kuid_t uid, struct hlist_head *hashent)
108{
109 struct user_struct *user;
110
111 hlist_for_each_entry(user, hashent, uidhash_node) {
112 if (uid_eq(user->uid, uid)) {
113 atomic_inc(&user->__count);
114 return user;
115 }
116 }
117
118 return NULL;
119}
120
121
122
123
124
125static void free_user(struct user_struct *up, unsigned long flags)
126 __releases(&uidhash_lock)
127{
128 uid_hash_remove(up);
129 spin_unlock_irqrestore(&uidhash_lock, flags);
130 key_put(up->uid_keyring);
131 key_put(up->session_keyring);
132 kmem_cache_free(uid_cachep, up);
133}
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139
140
141struct user_struct *find_user(kuid_t uid)
142{
143 struct user_struct *ret;
144 unsigned long flags;
145
146 spin_lock_irqsave(&uidhash_lock, flags);
147 ret = uid_hash_find(uid, uidhashentry(uid));
148 spin_unlock_irqrestore(&uidhash_lock, flags);
149 return ret;
150}
151
152void free_uid(struct user_struct *up)
153{
154 unsigned long flags;
155
156 if (!up)
157 return;
158
159 local_irq_save(flags);
160 if (atomic_dec_and_lock(&up->__count, &uidhash_lock))
161 free_user(up, flags);
162 else
163 local_irq_restore(flags);
164}
165
166struct user_struct *alloc_uid(kuid_t uid)
167{
168 struct hlist_head *hashent = uidhashentry(uid);
169 struct user_struct *up, *new;
170
171 spin_lock_irq(&uidhash_lock);
172 up = uid_hash_find(uid, hashent);
173 spin_unlock_irq(&uidhash_lock);
174
175 if (!up) {
176 new = kmem_cache_zalloc(uid_cachep, GFP_KERNEL);
177 if (!new)
178 goto out_unlock;
179
180 new->uid = uid;
181 atomic_set(&new->__count, 1);
182
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186
187 spin_lock_irq(&uidhash_lock);
188 up = uid_hash_find(uid, hashent);
189 if (up) {
190 key_put(new->uid_keyring);
191 key_put(new->session_keyring);
192 kmem_cache_free(uid_cachep, new);
193 } else {
194 uid_hash_insert(new, hashent);
195 up = new;
196 }
197 spin_unlock_irq(&uidhash_lock);
198 }
199
200 return up;
201
202out_unlock:
203 return NULL;
204}
205
206static int __init uid_cache_init(void)
207{
208 int n;
209
210 uid_cachep = kmem_cache_create("uid_cache", sizeof(struct user_struct),
211 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
212
213 for(n = 0; n < UIDHASH_SZ; ++n)
214 INIT_HLIST_HEAD(uidhash_table + n);
215
216
217 spin_lock_irq(&uidhash_lock);
218 uid_hash_insert(&root_user, uidhashentry(GLOBAL_ROOT_UID));
219 spin_unlock_irq(&uidhash_lock);
220
221 return 0;
222}
223
224module_init(uid_cache_init);
225