]> git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blame - kernel/user.c
notifier-error-inject: fix module names in Kconfig
[mirror_ubuntu-artful-kernel.git] / kernel / user.c
CommitLineData
1da177e4
LT
1/*
2 * The "user cache".
3 *
4 * (C) Copyright 1991-2000 Linus Torvalds
5 *
6 * We have a per-user structure to keep track of how many
7 * processes, files etc the user has claimed, in order to be
8 * able to have per-user limits for system resources.
9 */
10
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>
4021cb27 16#include <linux/interrupt.h>
9984de1a 17#include <linux/export.h>
acce292c 18#include <linux/user_namespace.h>
98f842e6 19#include <linux/proc_fs.h>
1da177e4 20
59607db3
SH
21/*
22 * userns count is 1 for root user, 1 for init_uts_ns,
23 * and 1 for... ?
24 */
aee16ce7 25struct user_namespace init_user_ns = {
22d917d8
EB
26 .uid_map = {
27 .nr_extents = 1,
28 .extent[0] = {
29 .first = 0,
30 .lower_first = 0,
4b06a81f 31 .count = 4294967295U,
22d917d8
EB
32 },
33 },
34 .gid_map = {
35 .nr_extents = 1,
36 .extent[0] = {
37 .first = 0,
38 .lower_first = 0,
4b06a81f 39 .count = 4294967295U,
22d917d8
EB
40 },
41 },
f76d207a
EB
42 .projid_map = {
43 .nr_extents = 1,
44 .extent[0] = {
45 .first = 0,
46 .lower_first = 0,
47 .count = 4294967295U,
48 },
49 },
c61a2810 50 .count = ATOMIC_INIT(3),
783291e6
EB
51 .owner = GLOBAL_ROOT_UID,
52 .group = GLOBAL_ROOT_GID,
98f842e6 53 .proc_inum = PROC_USER_INIT_INO,
87a8ebd6
EB
54 .may_mount_sysfs = true,
55 .may_mount_proc = true,
aee16ce7
PE
56};
57EXPORT_SYMBOL_GPL(init_user_ns);
58
1da177e4
LT
59/*
60 * UID task count cache, to get fast user lookup in "alloc_uid"
61 * when changing user ID's (ie setuid() and friends).
62 */
63
7b44ab97
EB
64#define UIDHASH_BITS (CONFIG_BASE_SMALL ? 3 : 7)
65#define UIDHASH_SZ (1 << UIDHASH_BITS)
1da177e4
LT
66#define UIDHASH_MASK (UIDHASH_SZ - 1)
67#define __uidhashfn(uid) (((uid >> UIDHASH_BITS) + uid) & UIDHASH_MASK)
7b44ab97 68#define uidhashentry(uid) (uidhash_table + __uidhashfn((__kuid_val(uid))))
1da177e4 69
e18b890b 70static struct kmem_cache *uid_cachep;
7b44ab97 71struct hlist_head uidhash_table[UIDHASH_SZ];
4021cb27
IM
72
73/*
74 * The uidhash_lock is mostly taken from process context, but it is
75 * occasionally also taken from softirq/tasklet context, when
76 * task-structs get RCU-freed. Hence all locking must be softirq-safe.
3fa97c9d
AM
77 * But free_uid() is also called with local interrupts disabled, and running
78 * local_bh_enable() with local interrupts disabled is an error - we'll run
79 * softirq callbacks, and they can unconditionally enable interrupts, and
80 * the caller of free_uid() didn't expect that..
4021cb27 81 */
1da177e4
LT
82static DEFINE_SPINLOCK(uidhash_lock);
83
783291e6 84/* root_user.__count is 1, for init task cred */
1da177e4 85struct user_struct root_user = {
783291e6 86 .__count = ATOMIC_INIT(1),
1da177e4
LT
87 .processes = ATOMIC_INIT(1),
88 .files = ATOMIC_INIT(0),
89 .sigpending = ATOMIC_INIT(0),
1da177e4 90 .locked_shm = 0,
7b44ab97 91 .uid = GLOBAL_ROOT_UID,
1da177e4
LT
92};
93
5cb350ba
DG
94/*
95 * These routines must be called with the uidhash spinlock held!
96 */
40aeb400 97static void uid_hash_insert(struct user_struct *up, struct hlist_head *hashent)
5cb350ba
DG
98{
99 hlist_add_head(&up->uidhash_node, hashent);
100}
101
40aeb400 102static void uid_hash_remove(struct user_struct *up)
5cb350ba
DG
103{
104 hlist_del_init(&up->uidhash_node);
105}
106
7b44ab97 107static struct user_struct *uid_hash_find(kuid_t uid, struct hlist_head *hashent)
3959214f
KS
108{
109 struct user_struct *user;
3959214f 110
b67bfe0d 111 hlist_for_each_entry(user, hashent, uidhash_node) {
7b44ab97 112 if (uid_eq(user->uid, uid)) {
3959214f
KS
113 atomic_inc(&user->__count);
114 return user;
115 }
116 }
117
118 return NULL;
119}
120
5cb350ba
DG
121/* IRQs are disabled and uidhash_lock is held upon function entry.
122 * IRQ state (as stored in flags) is restored and uidhash_lock released
123 * upon function exit.
124 */
18b6e041 125static void free_user(struct user_struct *up, unsigned long flags)
571428be 126 __releases(&uidhash_lock)
5cb350ba
DG
127{
128 uid_hash_remove(up);
129 spin_unlock_irqrestore(&uidhash_lock, flags);
5cb350ba
DG
130 key_put(up->uid_keyring);
131 key_put(up->session_keyring);
132 kmem_cache_free(uid_cachep, up);
133}
134
1da177e4
LT
135/*
136 * Locate the user_struct for the passed UID. If found, take a ref on it. The
137 * caller must undo that ref with free_uid().
138 *
139 * If the user_struct could not be found, return NULL.
140 */
7b44ab97 141struct user_struct *find_user(kuid_t uid)
1da177e4
LT
142{
143 struct user_struct *ret;
3fa97c9d 144 unsigned long flags;
1da177e4 145
3fa97c9d 146 spin_lock_irqsave(&uidhash_lock, flags);
7b44ab97 147 ret = uid_hash_find(uid, uidhashentry(uid));
3fa97c9d 148 spin_unlock_irqrestore(&uidhash_lock, flags);
1da177e4
LT
149 return ret;
150}
151
152void free_uid(struct user_struct *up)
153{
3fa97c9d
AM
154 unsigned long flags;
155
36f57413
AM
156 if (!up)
157 return;
158
3fa97c9d 159 local_irq_save(flags);
5cb350ba
DG
160 if (atomic_dec_and_lock(&up->__count, &uidhash_lock))
161 free_user(up, flags);
162 else
36f57413 163 local_irq_restore(flags);
1da177e4
LT
164}
165
7b44ab97 166struct user_struct *alloc_uid(kuid_t uid)
1da177e4 167{
7b44ab97 168 struct hlist_head *hashent = uidhashentry(uid);
8eb703e4 169 struct user_struct *up, *new;
1da177e4 170
3fa97c9d 171 spin_lock_irq(&uidhash_lock);
1da177e4 172 up = uid_hash_find(uid, hashent);
3fa97c9d 173 spin_unlock_irq(&uidhash_lock);
1da177e4
LT
174
175 if (!up) {
354a1f4d 176 new = kmem_cache_zalloc(uid_cachep, GFP_KERNEL);
8eb703e4
PE
177 if (!new)
178 goto out_unlock;
5e8869bb 179
1da177e4
LT
180 new->uid = uid;
181 atomic_set(&new->__count, 1);
1da177e4
LT
182
183 /*
184 * Before adding this, check whether we raced
185 * on adding the same user already..
186 */
3fa97c9d 187 spin_lock_irq(&uidhash_lock);
1da177e4
LT
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 }
3fa97c9d 197 spin_unlock_irq(&uidhash_lock);
1da177e4 198 }
5cb350ba 199
1da177e4 200 return up;
8eb703e4 201
8eb703e4 202out_unlock:
8eb703e4 203 return NULL;
1da177e4
LT
204}
205
1da177e4
LT
206static int __init uid_cache_init(void)
207{
208 int n;
209
210 uid_cachep = kmem_cache_create("uid_cache", sizeof(struct user_struct),
20c2df83 211 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1da177e4
LT
212
213 for(n = 0; n < UIDHASH_SZ; ++n)
7b44ab97 214 INIT_HLIST_HEAD(uidhash_table + n);
1da177e4
LT
215
216 /* Insert the root user immediately (init already runs as root) */
3fa97c9d 217 spin_lock_irq(&uidhash_lock);
7b44ab97 218 uid_hash_insert(&root_user, uidhashentry(GLOBAL_ROOT_UID));
3fa97c9d 219 spin_unlock_irq(&uidhash_lock);
1da177e4
LT
220
221 return 0;
222}
223
224module_init(uid_cache_init);