Commit | Line | Data |
---|---|---|
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> |
acce292c CLG |
17 | #include <linux/module.h> |
18 | #include <linux/user_namespace.h> | |
d84f4f99 | 19 | #include "cred-internals.h" |
1da177e4 | 20 | |
aee16ce7 PE |
21 | struct user_namespace init_user_ns = { |
22 | .kref = { | |
18b6e041 | 23 | .refcount = ATOMIC_INIT(1), |
aee16ce7 | 24 | }, |
18b6e041 | 25 | .creator = &root_user, |
aee16ce7 PE |
26 | }; |
27 | EXPORT_SYMBOL_GPL(init_user_ns); | |
28 | ||
1da177e4 LT |
29 | /* |
30 | * UID task count cache, to get fast user lookup in "alloc_uid" | |
31 | * when changing user ID's (ie setuid() and friends). | |
32 | */ | |
33 | ||
1da177e4 LT |
34 | #define UIDHASH_MASK (UIDHASH_SZ - 1) |
35 | #define __uidhashfn(uid) (((uid >> UIDHASH_BITS) + uid) & UIDHASH_MASK) | |
acce292c | 36 | #define uidhashentry(ns, uid) ((ns)->uidhash_table + __uidhashfn((uid))) |
1da177e4 | 37 | |
e18b890b | 38 | static struct kmem_cache *uid_cachep; |
4021cb27 IM |
39 | |
40 | /* | |
41 | * The uidhash_lock is mostly taken from process context, but it is | |
42 | * occasionally also taken from softirq/tasklet context, when | |
43 | * task-structs get RCU-freed. Hence all locking must be softirq-safe. | |
3fa97c9d AM |
44 | * But free_uid() is also called with local interrupts disabled, and running |
45 | * local_bh_enable() with local interrupts disabled is an error - we'll run | |
46 | * softirq callbacks, and they can unconditionally enable interrupts, and | |
47 | * the caller of free_uid() didn't expect that.. | |
4021cb27 | 48 | */ |
1da177e4 LT |
49 | static DEFINE_SPINLOCK(uidhash_lock); |
50 | ||
18b6e041 | 51 | /* root_user.__count is 2, 1 for init task cred, 1 for init_user_ns->creator */ |
1da177e4 | 52 | struct user_struct root_user = { |
18b6e041 | 53 | .__count = ATOMIC_INIT(2), |
1da177e4 LT |
54 | .processes = ATOMIC_INIT(1), |
55 | .files = ATOMIC_INIT(0), | |
56 | .sigpending = ATOMIC_INIT(0), | |
1da177e4 | 57 | .locked_shm = 0, |
18b6e041 | 58 | .user_ns = &init_user_ns, |
052f1dc7 | 59 | #ifdef CONFIG_USER_SCHED |
4cf86d77 | 60 | .tg = &init_task_group, |
24e377a8 | 61 | #endif |
1da177e4 LT |
62 | }; |
63 | ||
5cb350ba DG |
64 | /* |
65 | * These routines must be called with the uidhash spinlock held! | |
66 | */ | |
40aeb400 | 67 | static void uid_hash_insert(struct user_struct *up, struct hlist_head *hashent) |
5cb350ba DG |
68 | { |
69 | hlist_add_head(&up->uidhash_node, hashent); | |
70 | } | |
71 | ||
40aeb400 | 72 | static void uid_hash_remove(struct user_struct *up) |
5cb350ba DG |
73 | { |
74 | hlist_del_init(&up->uidhash_node); | |
fb5ae64f | 75 | put_user_ns(up->user_ns); |
5cb350ba DG |
76 | } |
77 | ||
40aeb400 | 78 | static struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent) |
5cb350ba DG |
79 | { |
80 | struct user_struct *user; | |
81 | struct hlist_node *h; | |
82 | ||
83 | hlist_for_each_entry(user, h, hashent, uidhash_node) { | |
84 | if (user->uid == uid) { | |
85 | atomic_inc(&user->__count); | |
86 | return user; | |
87 | } | |
88 | } | |
89 | ||
90 | return NULL; | |
91 | } | |
92 | ||
052f1dc7 | 93 | #ifdef CONFIG_USER_SCHED |
5cb350ba | 94 | |
24e377a8 SV |
95 | static void sched_destroy_user(struct user_struct *up) |
96 | { | |
97 | sched_destroy_group(up->tg); | |
98 | } | |
99 | ||
100 | static int sched_create_user(struct user_struct *up) | |
101 | { | |
102 | int rc = 0; | |
103 | ||
eff766a6 | 104 | up->tg = sched_create_group(&root_task_group); |
24e377a8 SV |
105 | if (IS_ERR(up->tg)) |
106 | rc = -ENOMEM; | |
107 | ||
6c415b92 AB |
108 | set_tg_uid(up); |
109 | ||
24e377a8 SV |
110 | return rc; |
111 | } | |
112 | ||
052f1dc7 | 113 | #else /* CONFIG_USER_SCHED */ |
b1a8c172 DG |
114 | |
115 | static void sched_destroy_user(struct user_struct *up) { } | |
116 | static int sched_create_user(struct user_struct *up) { return 0; } | |
b1a8c172 | 117 | |
052f1dc7 | 118 | #endif /* CONFIG_USER_SCHED */ |
b1a8c172 | 119 | |
052f1dc7 | 120 | #if defined(CONFIG_USER_SCHED) && defined(CONFIG_SYSFS) |
b1a8c172 | 121 | |
eb41d946 | 122 | static struct kset *uids_kset; /* represents the /sys/kernel/uids/ directory */ |
b1a8c172 DG |
123 | static DEFINE_MUTEX(uids_mutex); |
124 | ||
5cb350ba DG |
125 | static inline void uids_mutex_lock(void) |
126 | { | |
127 | mutex_lock(&uids_mutex); | |
128 | } | |
24e377a8 | 129 | |
5cb350ba DG |
130 | static inline void uids_mutex_unlock(void) |
131 | { | |
132 | mutex_unlock(&uids_mutex); | |
133 | } | |
24e377a8 | 134 | |
eb41d946 | 135 | /* uid directory attributes */ |
052f1dc7 | 136 | #ifdef CONFIG_FAIR_GROUP_SCHED |
eb41d946 KS |
137 | static ssize_t cpu_shares_show(struct kobject *kobj, |
138 | struct kobj_attribute *attr, | |
139 | char *buf) | |
5cb350ba | 140 | { |
eb41d946 | 141 | struct user_struct *up = container_of(kobj, struct user_struct, kobj); |
24e377a8 | 142 | |
eb41d946 | 143 | return sprintf(buf, "%lu\n", sched_group_shares(up->tg)); |
5cb350ba DG |
144 | } |
145 | ||
eb41d946 KS |
146 | static ssize_t cpu_shares_store(struct kobject *kobj, |
147 | struct kobj_attribute *attr, | |
148 | const char *buf, size_t size) | |
5cb350ba | 149 | { |
eb41d946 | 150 | struct user_struct *up = container_of(kobj, struct user_struct, kobj); |
5cb350ba DG |
151 | unsigned long shares; |
152 | int rc; | |
153 | ||
eb41d946 | 154 | sscanf(buf, "%lu", &shares); |
5cb350ba DG |
155 | |
156 | rc = sched_group_set_shares(up->tg, shares); | |
157 | ||
158 | return (rc ? rc : size); | |
159 | } | |
160 | ||
eb41d946 KS |
161 | static struct kobj_attribute cpu_share_attr = |
162 | __ATTR(cpu_share, 0644, cpu_shares_show, cpu_shares_store); | |
052f1dc7 | 163 | #endif |
eb41d946 | 164 | |
052f1dc7 | 165 | #ifdef CONFIG_RT_GROUP_SCHED |
9f0c1e56 PZ |
166 | static ssize_t cpu_rt_runtime_show(struct kobject *kobj, |
167 | struct kobj_attribute *attr, | |
168 | char *buf) | |
169 | { | |
170 | struct user_struct *up = container_of(kobj, struct user_struct, kobj); | |
171 | ||
af4491e5 | 172 | return sprintf(buf, "%ld\n", sched_group_rt_runtime(up->tg)); |
9f0c1e56 PZ |
173 | } |
174 | ||
175 | static ssize_t cpu_rt_runtime_store(struct kobject *kobj, | |
176 | struct kobj_attribute *attr, | |
177 | const char *buf, size_t size) | |
178 | { | |
179 | struct user_struct *up = container_of(kobj, struct user_struct, kobj); | |
180 | unsigned long rt_runtime; | |
181 | int rc; | |
182 | ||
af4491e5 | 183 | sscanf(buf, "%ld", &rt_runtime); |
9f0c1e56 PZ |
184 | |
185 | rc = sched_group_set_rt_runtime(up->tg, rt_runtime); | |
186 | ||
187 | return (rc ? rc : size); | |
188 | } | |
189 | ||
190 | static struct kobj_attribute cpu_rt_runtime_attr = | |
191 | __ATTR(cpu_rt_runtime, 0644, cpu_rt_runtime_show, cpu_rt_runtime_store); | |
d0b27fa7 PZ |
192 | |
193 | static ssize_t cpu_rt_period_show(struct kobject *kobj, | |
194 | struct kobj_attribute *attr, | |
195 | char *buf) | |
196 | { | |
197 | struct user_struct *up = container_of(kobj, struct user_struct, kobj); | |
198 | ||
199 | return sprintf(buf, "%lu\n", sched_group_rt_period(up->tg)); | |
200 | } | |
201 | ||
202 | static ssize_t cpu_rt_period_store(struct kobject *kobj, | |
203 | struct kobj_attribute *attr, | |
204 | const char *buf, size_t size) | |
205 | { | |
206 | struct user_struct *up = container_of(kobj, struct user_struct, kobj); | |
207 | unsigned long rt_period; | |
208 | int rc; | |
209 | ||
210 | sscanf(buf, "%lu", &rt_period); | |
211 | ||
212 | rc = sched_group_set_rt_period(up->tg, rt_period); | |
213 | ||
214 | return (rc ? rc : size); | |
215 | } | |
216 | ||
217 | static struct kobj_attribute cpu_rt_period_attr = | |
218 | __ATTR(cpu_rt_period, 0644, cpu_rt_period_show, cpu_rt_period_store); | |
052f1dc7 | 219 | #endif |
9f0c1e56 | 220 | |
eb41d946 KS |
221 | /* default attributes per uid directory */ |
222 | static struct attribute *uids_attributes[] = { | |
052f1dc7 | 223 | #ifdef CONFIG_FAIR_GROUP_SCHED |
eb41d946 | 224 | &cpu_share_attr.attr, |
052f1dc7 PZ |
225 | #endif |
226 | #ifdef CONFIG_RT_GROUP_SCHED | |
9f0c1e56 | 227 | &cpu_rt_runtime_attr.attr, |
d0b27fa7 | 228 | &cpu_rt_period_attr.attr, |
052f1dc7 | 229 | #endif |
eb41d946 KS |
230 | NULL |
231 | }; | |
232 | ||
233 | /* the lifetime of user_struct is not managed by the core (now) */ | |
234 | static void uids_release(struct kobject *kobj) | |
5cb350ba | 235 | { |
eb41d946 | 236 | return; |
5cb350ba DG |
237 | } |
238 | ||
eb41d946 KS |
239 | static struct kobj_type uids_ktype = { |
240 | .sysfs_ops = &kobj_sysfs_ops, | |
241 | .default_attrs = uids_attributes, | |
242 | .release = uids_release, | |
243 | }; | |
244 | ||
94d6a5f7 SH |
245 | /* |
246 | * Create /sys/kernel/uids/<uid>/cpu_share file for this user | |
247 | * We do not create this file for users in a user namespace (until | |
248 | * sysfs tagging is implemented). | |
249 | * | |
250 | * See Documentation/scheduler/sched-design-CFS.txt for ramifications. | |
251 | */ | |
eb41d946 | 252 | static int uids_user_create(struct user_struct *up) |
1da177e4 | 253 | { |
eb41d946 | 254 | struct kobject *kobj = &up->kobj; |
5cb350ba DG |
255 | int error; |
256 | ||
eb41d946 | 257 | memset(kobj, 0, sizeof(struct kobject)); |
c37bbb0f SH |
258 | if (up->user_ns != &init_user_ns) |
259 | return 0; | |
eb41d946 | 260 | kobj->kset = uids_kset; |
cf15126b GKH |
261 | error = kobject_init_and_add(kobj, &uids_ktype, NULL, "%d", up->uid); |
262 | if (error) { | |
263 | kobject_put(kobj); | |
5cb350ba | 264 | goto done; |
cf15126b | 265 | } |
5cb350ba | 266 | |
fb7dde37 | 267 | kobject_uevent(kobj, KOBJ_ADD); |
5cb350ba DG |
268 | done: |
269 | return error; | |
1da177e4 LT |
270 | } |
271 | ||
eb41d946 | 272 | /* create these entries in sysfs: |
5cb350ba DG |
273 | * "/sys/kernel/uids" directory |
274 | * "/sys/kernel/uids/0" directory (for root user) | |
275 | * "/sys/kernel/uids/0/cpu_share" file (for root user) | |
276 | */ | |
eb41d946 | 277 | int __init uids_sysfs_init(void) |
1da177e4 | 278 | { |
0ff21e46 | 279 | uids_kset = kset_create_and_add("uids", NULL, kernel_kobj); |
eb41d946 KS |
280 | if (!uids_kset) |
281 | return -ENOMEM; | |
5cb350ba | 282 | |
eb41d946 | 283 | return uids_user_create(&root_user); |
1da177e4 LT |
284 | } |
285 | ||
5cb350ba DG |
286 | /* work function to remove sysfs directory for a user and free up |
287 | * corresponding structures. | |
288 | */ | |
289 | static void remove_user_sysfs_dir(struct work_struct *w) | |
1da177e4 | 290 | { |
5cb350ba | 291 | struct user_struct *up = container_of(w, struct user_struct, work); |
5cb350ba DG |
292 | unsigned long flags; |
293 | int remove_user = 0; | |
1da177e4 | 294 | |
c37bbb0f SH |
295 | if (up->user_ns != &init_user_ns) |
296 | return; | |
5cb350ba DG |
297 | /* Make uid_hash_remove() + sysfs_remove_file() + kobject_del() |
298 | * atomic. | |
299 | */ | |
300 | uids_mutex_lock(); | |
301 | ||
302 | local_irq_save(flags); | |
303 | ||
304 | if (atomic_dec_and_lock(&up->__count, &uidhash_lock)) { | |
305 | uid_hash_remove(up); | |
306 | remove_user = 1; | |
307 | spin_unlock_irqrestore(&uidhash_lock, flags); | |
308 | } else { | |
309 | local_irq_restore(flags); | |
1da177e4 LT |
310 | } |
311 | ||
5cb350ba DG |
312 | if (!remove_user) |
313 | goto done; | |
314 | ||
eb41d946 KS |
315 | kobject_uevent(&up->kobj, KOBJ_REMOVE); |
316 | kobject_del(&up->kobj); | |
317 | kobject_put(&up->kobj); | |
5cb350ba DG |
318 | |
319 | sched_destroy_user(up); | |
320 | key_put(up->uid_keyring); | |
321 | key_put(up->session_keyring); | |
322 | kmem_cache_free(uid_cachep, up); | |
323 | ||
324 | done: | |
325 | uids_mutex_unlock(); | |
326 | } | |
327 | ||
328 | /* IRQs are disabled and uidhash_lock is held upon function entry. | |
329 | * IRQ state (as stored in flags) is restored and uidhash_lock released | |
330 | * upon function exit. | |
331 | */ | |
18b6e041 | 332 | static void free_user(struct user_struct *up, unsigned long flags) |
5cb350ba DG |
333 | { |
334 | /* restore back the count */ | |
335 | atomic_inc(&up->__count); | |
336 | spin_unlock_irqrestore(&uidhash_lock, flags); | |
337 | ||
338 | INIT_WORK(&up->work, remove_user_sysfs_dir); | |
339 | schedule_work(&up->work); | |
1da177e4 LT |
340 | } |
341 | ||
052f1dc7 | 342 | #else /* CONFIG_USER_SCHED && CONFIG_SYSFS */ |
5cb350ba | 343 | |
eb41d946 KS |
344 | int uids_sysfs_init(void) { return 0; } |
345 | static inline int uids_user_create(struct user_struct *up) { return 0; } | |
5cb350ba DG |
346 | static inline void uids_mutex_lock(void) { } |
347 | static inline void uids_mutex_unlock(void) { } | |
348 | ||
349 | /* IRQs are disabled and uidhash_lock is held upon function entry. | |
350 | * IRQ state (as stored in flags) is restored and uidhash_lock released | |
351 | * upon function exit. | |
352 | */ | |
18b6e041 | 353 | static void free_user(struct user_struct *up, unsigned long flags) |
5cb350ba DG |
354 | { |
355 | uid_hash_remove(up); | |
356 | spin_unlock_irqrestore(&uidhash_lock, flags); | |
357 | sched_destroy_user(up); | |
358 | key_put(up->uid_keyring); | |
359 | key_put(up->session_keyring); | |
360 | kmem_cache_free(uid_cachep, up); | |
361 | } | |
362 | ||
b1a8c172 | 363 | #endif |
5cb350ba | 364 | |
1da177e4 LT |
365 | /* |
366 | * Locate the user_struct for the passed UID. If found, take a ref on it. The | |
367 | * caller must undo that ref with free_uid(). | |
368 | * | |
369 | * If the user_struct could not be found, return NULL. | |
370 | */ | |
371 | struct user_struct *find_user(uid_t uid) | |
372 | { | |
373 | struct user_struct *ret; | |
3fa97c9d | 374 | unsigned long flags; |
6ded6ab9 | 375 | struct user_namespace *ns = current_user_ns(); |
1da177e4 | 376 | |
3fa97c9d | 377 | spin_lock_irqsave(&uidhash_lock, flags); |
acce292c | 378 | ret = uid_hash_find(uid, uidhashentry(ns, uid)); |
3fa97c9d | 379 | spin_unlock_irqrestore(&uidhash_lock, flags); |
1da177e4 LT |
380 | return ret; |
381 | } | |
382 | ||
383 | void free_uid(struct user_struct *up) | |
384 | { | |
3fa97c9d AM |
385 | unsigned long flags; |
386 | ||
36f57413 AM |
387 | if (!up) |
388 | return; | |
389 | ||
3fa97c9d | 390 | local_irq_save(flags); |
5cb350ba DG |
391 | if (atomic_dec_and_lock(&up->__count, &uidhash_lock)) |
392 | free_user(up, flags); | |
393 | else | |
36f57413 | 394 | local_irq_restore(flags); |
1da177e4 LT |
395 | } |
396 | ||
354a1f4d | 397 | struct user_struct *alloc_uid(struct user_namespace *ns, uid_t uid) |
1da177e4 | 398 | { |
735de223 | 399 | struct hlist_head *hashent = uidhashentry(ns, uid); |
8eb703e4 | 400 | struct user_struct *up, *new; |
1da177e4 | 401 | |
eb41d946 | 402 | /* Make uid_hash_find() + uids_user_create() + uid_hash_insert() |
5cb350ba DG |
403 | * atomic. |
404 | */ | |
405 | uids_mutex_lock(); | |
406 | ||
3fa97c9d | 407 | spin_lock_irq(&uidhash_lock); |
1da177e4 | 408 | up = uid_hash_find(uid, hashent); |
3fa97c9d | 409 | spin_unlock_irq(&uidhash_lock); |
1da177e4 LT |
410 | |
411 | if (!up) { | |
354a1f4d | 412 | new = kmem_cache_zalloc(uid_cachep, GFP_KERNEL); |
8eb703e4 PE |
413 | if (!new) |
414 | goto out_unlock; | |
5e8869bb | 415 | |
1da177e4 LT |
416 | new->uid = uid; |
417 | atomic_set(&new->__count, 1); | |
1da177e4 | 418 | |
8eb703e4 | 419 | if (sched_create_user(new) < 0) |
69664cf1 | 420 | goto out_free_user; |
24e377a8 | 421 | |
18b6e041 SH |
422 | new->user_ns = get_user_ns(ns); |
423 | ||
8eb703e4 PE |
424 | if (uids_user_create(new)) |
425 | goto out_destoy_sched; | |
5cb350ba | 426 | |
1da177e4 LT |
427 | /* |
428 | * Before adding this, check whether we raced | |
429 | * on adding the same user already.. | |
430 | */ | |
3fa97c9d | 431 | spin_lock_irq(&uidhash_lock); |
1da177e4 LT |
432 | up = uid_hash_find(uid, hashent); |
433 | if (up) { | |
052f1dc7 | 434 | /* This case is not possible when CONFIG_USER_SCHED |
5cb350ba DG |
435 | * is defined, since we serialize alloc_uid() using |
436 | * uids_mutex. Hence no need to call | |
437 | * sched_destroy_user() or remove_user_sysfs_dir(). | |
438 | */ | |
1da177e4 LT |
439 | key_put(new->uid_keyring); |
440 | key_put(new->session_keyring); | |
441 | kmem_cache_free(uid_cachep, new); | |
442 | } else { | |
443 | uid_hash_insert(new, hashent); | |
444 | up = new; | |
445 | } | |
3fa97c9d | 446 | spin_unlock_irq(&uidhash_lock); |
1da177e4 | 447 | } |
5cb350ba DG |
448 | |
449 | uids_mutex_unlock(); | |
450 | ||
1da177e4 | 451 | return up; |
8eb703e4 PE |
452 | |
453 | out_destoy_sched: | |
454 | sched_destroy_user(new); | |
18b6e041 | 455 | put_user_ns(new->user_ns); |
8eb703e4 PE |
456 | out_free_user: |
457 | kmem_cache_free(uid_cachep, new); | |
458 | out_unlock: | |
459 | uids_mutex_unlock(); | |
460 | return NULL; | |
1da177e4 LT |
461 | } |
462 | ||
1da177e4 LT |
463 | static int __init uid_cache_init(void) |
464 | { | |
465 | int n; | |
466 | ||
467 | uid_cachep = kmem_cache_create("uid_cache", sizeof(struct user_struct), | |
20c2df83 | 468 | 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
1da177e4 LT |
469 | |
470 | for(n = 0; n < UIDHASH_SZ; ++n) | |
735de223 | 471 | INIT_HLIST_HEAD(init_user_ns.uidhash_table + n); |
1da177e4 LT |
472 | |
473 | /* Insert the root user immediately (init already runs as root) */ | |
3fa97c9d | 474 | spin_lock_irq(&uidhash_lock); |
acce292c | 475 | uid_hash_insert(&root_user, uidhashentry(&init_user_ns, 0)); |
3fa97c9d | 476 | spin_unlock_irq(&uidhash_lock); |
1da177e4 LT |
477 | |
478 | return 0; | |
479 | } | |
480 | ||
481 | module_init(uid_cache_init); |