Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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> |
Ingo Molnar | 4021cb2 | 2006-01-25 15:23:07 +0100 | [diff] [blame] | 16 | #include <linux/interrupt.h> |
Paul Gortmaker | 9984de1 | 2011-05-23 14:51:41 -0400 | [diff] [blame] | 17 | #include <linux/export.h> |
Cedric Le Goater | acce292 | 2007-07-15 23:40:59 -0700 | [diff] [blame] | 18 | #include <linux/user_namespace.h> |
SamarV-121 | b575711 | 2020-09-21 05:47:44 +0000 | [diff] [blame] | 19 | #include <linux/proc_fs.h> |
David Howells | 0bb80f2 | 2013-04-12 01:50:06 +0100 | [diff] [blame] | 20 | #include <linux/proc_ns.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 21 | |
Serge E. Hallyn | 59607db | 2011-03-23 16:43:16 -0700 | [diff] [blame] | 22 | /* |
| 23 | * userns count is 1 for root user, 1 for init_uts_ns, |
| 24 | * and 1 for... ? |
| 25 | */ |
Pavel Emelyanov | aee16ce | 2008-02-08 04:18:23 -0800 | [diff] [blame] | 26 | struct user_namespace init_user_ns = { |
Eric W. Biederman | 22d917d | 2011-11-17 00:11:58 -0800 | [diff] [blame] | 27 | .uid_map = { |
| 28 | .nr_extents = 1, |
| 29 | .extent[0] = { |
| 30 | .first = 0, |
| 31 | .lower_first = 0, |
Eric W. Biederman | 4b06a81 | 2012-05-19 15:44:06 -0600 | [diff] [blame] | 32 | .count = 4294967295U, |
Eric W. Biederman | 22d917d | 2011-11-17 00:11:58 -0800 | [diff] [blame] | 33 | }, |
| 34 | }, |
| 35 | .gid_map = { |
| 36 | .nr_extents = 1, |
| 37 | .extent[0] = { |
| 38 | .first = 0, |
| 39 | .lower_first = 0, |
Eric W. Biederman | 4b06a81 | 2012-05-19 15:44:06 -0600 | [diff] [blame] | 40 | .count = 4294967295U, |
Eric W. Biederman | 22d917d | 2011-11-17 00:11:58 -0800 | [diff] [blame] | 41 | }, |
| 42 | }, |
Eric W. Biederman | f76d207 | 2012-08-30 01:24:05 -0700 | [diff] [blame] | 43 | .projid_map = { |
| 44 | .nr_extents = 1, |
| 45 | .extent[0] = { |
| 46 | .first = 0, |
| 47 | .lower_first = 0, |
| 48 | .count = 4294967295U, |
| 49 | }, |
| 50 | }, |
Eric W. Biederman | c61a281 | 2012-12-28 18:58:39 -0800 | [diff] [blame] | 51 | .count = ATOMIC_INIT(3), |
Eric W. Biederman | 783291e | 2011-11-17 01:32:59 -0800 | [diff] [blame] | 52 | .owner = GLOBAL_ROOT_UID, |
| 53 | .group = GLOBAL_ROOT_GID, |
Al Viro | 435d5f4 | 2014-10-31 22:56:04 -0400 | [diff] [blame] | 54 | .ns.inum = PROC_USER_INIT_INO, |
Al Viro | 33c4294 | 2014-11-01 02:32:53 -0400 | [diff] [blame] | 55 | #ifdef CONFIG_USER_NS |
| 56 | .ns.ops = &userns_operations, |
| 57 | #endif |
Eric W. Biederman | 9cc4651 | 2014-12-02 12:27:26 -0600 | [diff] [blame] | 58 | .flags = USERNS_INIT_FLAGS, |
Xiao Guangrong | 6bd364d | 2013-12-13 15:00:32 +0800 | [diff] [blame] | 59 | #ifdef CONFIG_PERSISTENT_KEYRINGS |
| 60 | .persistent_keyring_register_sem = |
| 61 | __RWSEM_INITIALIZER(init_user_ns.persistent_keyring_register_sem), |
David Howells | f36f8c7 | 2013-09-24 10:35:19 +0100 | [diff] [blame] | 62 | #endif |
Pavel Emelyanov | aee16ce | 2008-02-08 04:18:23 -0800 | [diff] [blame] | 63 | }; |
| 64 | EXPORT_SYMBOL_GPL(init_user_ns); |
| 65 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 66 | /* |
| 67 | * UID task count cache, to get fast user lookup in "alloc_uid" |
| 68 | * when changing user ID's (ie setuid() and friends). |
| 69 | */ |
| 70 | |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 71 | #define UIDHASH_BITS (CONFIG_BASE_SMALL ? 3 : 7) |
| 72 | #define UIDHASH_SZ (1 << UIDHASH_BITS) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 73 | #define UIDHASH_MASK (UIDHASH_SZ - 1) |
| 74 | #define __uidhashfn(uid) (((uid >> UIDHASH_BITS) + uid) & UIDHASH_MASK) |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 75 | #define uidhashentry(uid) (uidhash_table + __uidhashfn((__kuid_val(uid)))) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 76 | |
Christoph Lameter | e18b890 | 2006-12-06 20:33:20 -0800 | [diff] [blame] | 77 | static struct kmem_cache *uid_cachep; |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 78 | struct hlist_head uidhash_table[UIDHASH_SZ]; |
Ingo Molnar | 4021cb2 | 2006-01-25 15:23:07 +0100 | [diff] [blame] | 79 | |
| 80 | /* |
| 81 | * The uidhash_lock is mostly taken from process context, but it is |
| 82 | * occasionally also taken from softirq/tasklet context, when |
| 83 | * task-structs get RCU-freed. Hence all locking must be softirq-safe. |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 84 | * But free_uid() is also called with local interrupts disabled, and running |
| 85 | * local_bh_enable() with local interrupts disabled is an error - we'll run |
| 86 | * softirq callbacks, and they can unconditionally enable interrupts, and |
| 87 | * the caller of free_uid() didn't expect that.. |
Ingo Molnar | 4021cb2 | 2006-01-25 15:23:07 +0100 | [diff] [blame] | 88 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 89 | static DEFINE_SPINLOCK(uidhash_lock); |
| 90 | |
Eric W. Biederman | 783291e | 2011-11-17 01:32:59 -0800 | [diff] [blame] | 91 | /* root_user.__count is 1, for init task cred */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 92 | struct user_struct root_user = { |
Eric W. Biederman | 783291e | 2011-11-17 01:32:59 -0800 | [diff] [blame] | 93 | .__count = ATOMIC_INIT(1), |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 94 | .processes = ATOMIC_INIT(1), |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 95 | .sigpending = ATOMIC_INIT(0), |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 96 | .locked_shm = 0, |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 97 | .uid = GLOBAL_ROOT_UID, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 98 | }; |
| 99 | |
Dhaval Giani | 5cb350b | 2007-10-15 17:00:14 +0200 | [diff] [blame] | 100 | /* |
| 101 | * These routines must be called with the uidhash spinlock held! |
| 102 | */ |
Alexey Dobriyan | 40aeb40 | 2007-10-16 23:30:09 -0700 | [diff] [blame] | 103 | static void uid_hash_insert(struct user_struct *up, struct hlist_head *hashent) |
Dhaval Giani | 5cb350b | 2007-10-15 17:00:14 +0200 | [diff] [blame] | 104 | { |
| 105 | hlist_add_head(&up->uidhash_node, hashent); |
| 106 | } |
| 107 | |
Alexey Dobriyan | 40aeb40 | 2007-10-16 23:30:09 -0700 | [diff] [blame] | 108 | static void uid_hash_remove(struct user_struct *up) |
Dhaval Giani | 5cb350b | 2007-10-15 17:00:14 +0200 | [diff] [blame] | 109 | { |
| 110 | hlist_del_init(&up->uidhash_node); |
| 111 | } |
| 112 | |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 113 | static struct user_struct *uid_hash_find(kuid_t uid, struct hlist_head *hashent) |
Kay Sievers | 3959214 | 2009-03-24 15:43:30 +0100 | [diff] [blame] | 114 | { |
| 115 | struct user_struct *user; |
Kay Sievers | 3959214 | 2009-03-24 15:43:30 +0100 | [diff] [blame] | 116 | |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 117 | hlist_for_each_entry(user, hashent, uidhash_node) { |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 118 | if (uid_eq(user->uid, uid)) { |
Kay Sievers | 3959214 | 2009-03-24 15:43:30 +0100 | [diff] [blame] | 119 | atomic_inc(&user->__count); |
| 120 | return user; |
| 121 | } |
| 122 | } |
| 123 | |
| 124 | return NULL; |
| 125 | } |
| 126 | |
Dhaval Giani | 5cb350b | 2007-10-15 17:00:14 +0200 | [diff] [blame] | 127 | /* IRQs are disabled and uidhash_lock is held upon function entry. |
| 128 | * IRQ state (as stored in flags) is restored and uidhash_lock released |
| 129 | * upon function exit. |
| 130 | */ |
Serge Hallyn | 18b6e04 | 2008-10-15 16:38:45 -0500 | [diff] [blame] | 131 | static void free_user(struct user_struct *up, unsigned long flags) |
Namhyung Kim | 571428b | 2010-10-26 14:22:43 -0700 | [diff] [blame] | 132 | __releases(&uidhash_lock) |
Dhaval Giani | 5cb350b | 2007-10-15 17:00:14 +0200 | [diff] [blame] | 133 | { |
| 134 | uid_hash_remove(up); |
| 135 | spin_unlock_irqrestore(&uidhash_lock, flags); |
Dhaval Giani | 5cb350b | 2007-10-15 17:00:14 +0200 | [diff] [blame] | 136 | key_put(up->uid_keyring); |
| 137 | key_put(up->session_keyring); |
| 138 | kmem_cache_free(uid_cachep, up); |
| 139 | } |
Srivatsa Vaddagiri | 24e377a | 2007-10-15 17:00:09 +0200 | [diff] [blame] | 140 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 141 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 142 | * Locate the user_struct for the passed UID. If found, take a ref on it. The |
| 143 | * caller must undo that ref with free_uid(). |
| 144 | * |
| 145 | * If the user_struct could not be found, return NULL. |
| 146 | */ |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 147 | struct user_struct *find_user(kuid_t uid) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 148 | { |
| 149 | struct user_struct *ret; |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 150 | unsigned long flags; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 151 | |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 152 | spin_lock_irqsave(&uidhash_lock, flags); |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 153 | ret = uid_hash_find(uid, uidhashentry(uid)); |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 154 | spin_unlock_irqrestore(&uidhash_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 155 | return ret; |
| 156 | } |
| 157 | |
| 158 | void free_uid(struct user_struct *up) |
| 159 | { |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 160 | unsigned long flags; |
| 161 | |
Andrew Morton | 36f5741 | 2006-03-24 03:15:47 -0800 | [diff] [blame] | 162 | if (!up) |
| 163 | return; |
| 164 | |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 165 | local_irq_save(flags); |
Dhaval Giani | 5cb350b | 2007-10-15 17:00:14 +0200 | [diff] [blame] | 166 | if (atomic_dec_and_lock(&up->__count, &uidhash_lock)) |
| 167 | free_user(up, flags); |
| 168 | else |
Andrew Morton | 36f5741 | 2006-03-24 03:15:47 -0800 | [diff] [blame] | 169 | local_irq_restore(flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 170 | } |
| 171 | |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 172 | struct user_struct *alloc_uid(kuid_t uid) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 173 | { |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 174 | struct hlist_head *hashent = uidhashentry(uid); |
Pavel Emelyanov | 8eb703e | 2008-01-25 21:08:26 +0100 | [diff] [blame] | 175 | struct user_struct *up, *new; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 176 | |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 177 | spin_lock_irq(&uidhash_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 178 | up = uid_hash_find(uid, hashent); |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 179 | spin_unlock_irq(&uidhash_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 180 | |
| 181 | if (!up) { |
Andrew Morton | 354a1f4 | 2008-04-30 00:54:54 -0700 | [diff] [blame] | 182 | new = kmem_cache_zalloc(uid_cachep, GFP_KERNEL); |
Pavel Emelyanov | 8eb703e | 2008-01-25 21:08:26 +0100 | [diff] [blame] | 183 | if (!new) |
| 184 | goto out_unlock; |
Pavel Emelyanov | 5e8869b | 2007-11-26 21:21:49 +0100 | [diff] [blame] | 185 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 186 | new->uid = uid; |
| 187 | atomic_set(&new->__count, 1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 188 | |
| 189 | /* |
| 190 | * Before adding this, check whether we raced |
| 191 | * on adding the same user already.. |
| 192 | */ |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 193 | spin_lock_irq(&uidhash_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 194 | up = uid_hash_find(uid, hashent); |
| 195 | if (up) { |
| 196 | key_put(new->uid_keyring); |
| 197 | key_put(new->session_keyring); |
| 198 | kmem_cache_free(uid_cachep, new); |
| 199 | } else { |
| 200 | uid_hash_insert(new, hashent); |
| 201 | up = new; |
| 202 | } |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 203 | spin_unlock_irq(&uidhash_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 204 | } |
SamarV-121 | b575711 | 2020-09-21 05:47:44 +0000 | [diff] [blame] | 205 | proc_register_uid(uid); |
Dhaval Giani | 5cb350b | 2007-10-15 17:00:14 +0200 | [diff] [blame] | 206 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 207 | return up; |
Pavel Emelyanov | 8eb703e | 2008-01-25 21:08:26 +0100 | [diff] [blame] | 208 | |
Pavel Emelyanov | 8eb703e | 2008-01-25 21:08:26 +0100 | [diff] [blame] | 209 | out_unlock: |
Pavel Emelyanov | 8eb703e | 2008-01-25 21:08:26 +0100 | [diff] [blame] | 210 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 211 | } |
| 212 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 213 | static int __init uid_cache_init(void) |
| 214 | { |
| 215 | int n; |
| 216 | |
| 217 | uid_cachep = kmem_cache_create("uid_cache", sizeof(struct user_struct), |
Paul Mundt | 20c2df8 | 2007-07-20 10:11:58 +0900 | [diff] [blame] | 218 | 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 219 | |
| 220 | for(n = 0; n < UIDHASH_SZ; ++n) |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 221 | INIT_HLIST_HEAD(uidhash_table + n); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 222 | |
| 223 | /* Insert the root user immediately (init already runs as root) */ |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 224 | spin_lock_irq(&uidhash_lock); |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 225 | uid_hash_insert(&root_user, uidhashentry(GLOBAL_ROOT_UID)); |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 226 | spin_unlock_irq(&uidhash_lock); |
SamarV-121 | b575711 | 2020-09-21 05:47:44 +0000 | [diff] [blame] | 227 | proc_register_uid(GLOBAL_ROOT_UID); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 228 | |
| 229 | return 0; |
| 230 | } |
Paul Gortmaker | c96d6660 | 2014-04-03 14:48:35 -0700 | [diff] [blame] | 231 | subsys_initcall(uid_cache_init); |