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> |
Eric W. Biederman | 98f842e | 2011-06-15 10:21:48 -0700 | [diff] [blame] | 19 | #include <linux/proc_fs.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 20 | |
Serge E. Hallyn | 59607db | 2011-03-23 16:43:16 -0700 | [diff] [blame] | 21 | /* |
| 22 | * userns count is 1 for root user, 1 for init_uts_ns, |
| 23 | * and 1 for... ? |
| 24 | */ |
Pavel Emelyanov | aee16ce | 2008-02-08 04:18:23 -0800 | [diff] [blame] | 25 | struct user_namespace init_user_ns = { |
Eric W. Biederman | 22d917d | 2011-11-17 00:11:58 -0800 | [diff] [blame] | 26 | .uid_map = { |
| 27 | .nr_extents = 1, |
| 28 | .extent[0] = { |
| 29 | .first = 0, |
| 30 | .lower_first = 0, |
Eric W. Biederman | 4b06a81 | 2012-05-19 15:44:06 -0600 | [diff] [blame] | 31 | .count = 4294967295U, |
Eric W. Biederman | 22d917d | 2011-11-17 00:11:58 -0800 | [diff] [blame] | 32 | }, |
| 33 | }, |
| 34 | .gid_map = { |
| 35 | .nr_extents = 1, |
| 36 | .extent[0] = { |
| 37 | .first = 0, |
| 38 | .lower_first = 0, |
Eric W. Biederman | 4b06a81 | 2012-05-19 15:44:06 -0600 | [diff] [blame] | 39 | .count = 4294967295U, |
Eric W. Biederman | 22d917d | 2011-11-17 00:11:58 -0800 | [diff] [blame] | 40 | }, |
| 41 | }, |
Eric W. Biederman | f76d207 | 2012-08-30 01:24:05 -0700 | [diff] [blame] | 42 | .projid_map = { |
| 43 | .nr_extents = 1, |
| 44 | .extent[0] = { |
| 45 | .first = 0, |
| 46 | .lower_first = 0, |
| 47 | .count = 4294967295U, |
| 48 | }, |
| 49 | }, |
Eric W. Biederman | c61a281 | 2012-12-28 18:58:39 -0800 | [diff] [blame] | 50 | .count = ATOMIC_INIT(3), |
Eric W. Biederman | 783291e | 2011-11-17 01:32:59 -0800 | [diff] [blame] | 51 | .owner = GLOBAL_ROOT_UID, |
| 52 | .group = GLOBAL_ROOT_GID, |
Eric W. Biederman | 98f842e | 2011-06-15 10:21:48 -0700 | [diff] [blame] | 53 | .proc_inum = PROC_USER_INIT_INO, |
Pavel Emelyanov | aee16ce | 2008-02-08 04:18:23 -0800 | [diff] [blame] | 54 | }; |
| 55 | EXPORT_SYMBOL_GPL(init_user_ns); |
| 56 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 57 | /* |
| 58 | * UID task count cache, to get fast user lookup in "alloc_uid" |
| 59 | * when changing user ID's (ie setuid() and friends). |
| 60 | */ |
| 61 | |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 62 | #define UIDHASH_BITS (CONFIG_BASE_SMALL ? 3 : 7) |
| 63 | #define UIDHASH_SZ (1 << UIDHASH_BITS) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 64 | #define UIDHASH_MASK (UIDHASH_SZ - 1) |
| 65 | #define __uidhashfn(uid) (((uid >> UIDHASH_BITS) + uid) & UIDHASH_MASK) |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 66 | #define uidhashentry(uid) (uidhash_table + __uidhashfn((__kuid_val(uid)))) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 67 | |
Christoph Lameter | e18b890 | 2006-12-06 20:33:20 -0800 | [diff] [blame] | 68 | static struct kmem_cache *uid_cachep; |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 69 | struct hlist_head uidhash_table[UIDHASH_SZ]; |
Ingo Molnar | 4021cb2 | 2006-01-25 15:23:07 +0100 | [diff] [blame] | 70 | |
| 71 | /* |
| 72 | * The uidhash_lock is mostly taken from process context, but it is |
| 73 | * occasionally also taken from softirq/tasklet context, when |
| 74 | * task-structs get RCU-freed. Hence all locking must be softirq-safe. |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 75 | * But free_uid() is also called with local interrupts disabled, and running |
| 76 | * local_bh_enable() with local interrupts disabled is an error - we'll run |
| 77 | * softirq callbacks, and they can unconditionally enable interrupts, and |
| 78 | * the caller of free_uid() didn't expect that.. |
Ingo Molnar | 4021cb2 | 2006-01-25 15:23:07 +0100 | [diff] [blame] | 79 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 80 | static DEFINE_SPINLOCK(uidhash_lock); |
| 81 | |
Eric W. Biederman | 783291e | 2011-11-17 01:32:59 -0800 | [diff] [blame] | 82 | /* root_user.__count is 1, for init task cred */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 83 | struct user_struct root_user = { |
Eric W. Biederman | 783291e | 2011-11-17 01:32:59 -0800 | [diff] [blame] | 84 | .__count = ATOMIC_INIT(1), |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 85 | .processes = ATOMIC_INIT(1), |
| 86 | .files = ATOMIC_INIT(0), |
| 87 | .sigpending = ATOMIC_INIT(0), |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 88 | .locked_shm = 0, |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 89 | .uid = GLOBAL_ROOT_UID, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 90 | }; |
| 91 | |
Dhaval Giani | 5cb350b | 2007-10-15 17:00:14 +0200 | [diff] [blame] | 92 | /* |
| 93 | * These routines must be called with the uidhash spinlock held! |
| 94 | */ |
Alexey Dobriyan | 40aeb40 | 2007-10-16 23:30:09 -0700 | [diff] [blame] | 95 | 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] | 96 | { |
| 97 | hlist_add_head(&up->uidhash_node, hashent); |
| 98 | } |
| 99 | |
Alexey Dobriyan | 40aeb40 | 2007-10-16 23:30:09 -0700 | [diff] [blame] | 100 | static void uid_hash_remove(struct user_struct *up) |
Dhaval Giani | 5cb350b | 2007-10-15 17:00:14 +0200 | [diff] [blame] | 101 | { |
| 102 | hlist_del_init(&up->uidhash_node); |
| 103 | } |
| 104 | |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 105 | 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] | 106 | { |
| 107 | struct user_struct *user; |
Kay Sievers | 3959214 | 2009-03-24 15:43:30 +0100 | [diff] [blame] | 108 | |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame^] | 109 | hlist_for_each_entry(user, hashent, uidhash_node) { |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 110 | if (uid_eq(user->uid, uid)) { |
Kay Sievers | 3959214 | 2009-03-24 15:43:30 +0100 | [diff] [blame] | 111 | atomic_inc(&user->__count); |
| 112 | return user; |
| 113 | } |
| 114 | } |
| 115 | |
| 116 | return NULL; |
| 117 | } |
| 118 | |
Dhaval Giani | 5cb350b | 2007-10-15 17:00:14 +0200 | [diff] [blame] | 119 | /* IRQs are disabled and uidhash_lock is held upon function entry. |
| 120 | * IRQ state (as stored in flags) is restored and uidhash_lock released |
| 121 | * upon function exit. |
| 122 | */ |
Serge Hallyn | 18b6e04 | 2008-10-15 16:38:45 -0500 | [diff] [blame] | 123 | static void free_user(struct user_struct *up, unsigned long flags) |
Namhyung Kim | 571428b | 2010-10-26 14:22:43 -0700 | [diff] [blame] | 124 | __releases(&uidhash_lock) |
Dhaval Giani | 5cb350b | 2007-10-15 17:00:14 +0200 | [diff] [blame] | 125 | { |
| 126 | uid_hash_remove(up); |
| 127 | spin_unlock_irqrestore(&uidhash_lock, flags); |
Dhaval Giani | 5cb350b | 2007-10-15 17:00:14 +0200 | [diff] [blame] | 128 | key_put(up->uid_keyring); |
| 129 | key_put(up->session_keyring); |
| 130 | kmem_cache_free(uid_cachep, up); |
| 131 | } |
Srivatsa Vaddagiri | 24e377a | 2007-10-15 17:00:09 +0200 | [diff] [blame] | 132 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 133 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 134 | * Locate the user_struct for the passed UID. If found, take a ref on it. The |
| 135 | * caller must undo that ref with free_uid(). |
| 136 | * |
| 137 | * If the user_struct could not be found, return NULL. |
| 138 | */ |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 139 | struct user_struct *find_user(kuid_t uid) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 140 | { |
| 141 | struct user_struct *ret; |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 142 | unsigned long flags; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 143 | |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 144 | spin_lock_irqsave(&uidhash_lock, flags); |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 145 | ret = uid_hash_find(uid, uidhashentry(uid)); |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 146 | spin_unlock_irqrestore(&uidhash_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 147 | return ret; |
| 148 | } |
| 149 | |
| 150 | void free_uid(struct user_struct *up) |
| 151 | { |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 152 | unsigned long flags; |
| 153 | |
Andrew Morton | 36f5741 | 2006-03-24 03:15:47 -0800 | [diff] [blame] | 154 | if (!up) |
| 155 | return; |
| 156 | |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 157 | local_irq_save(flags); |
Dhaval Giani | 5cb350b | 2007-10-15 17:00:14 +0200 | [diff] [blame] | 158 | if (atomic_dec_and_lock(&up->__count, &uidhash_lock)) |
| 159 | free_user(up, flags); |
| 160 | else |
Andrew Morton | 36f5741 | 2006-03-24 03:15:47 -0800 | [diff] [blame] | 161 | local_irq_restore(flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 162 | } |
| 163 | |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 164 | struct user_struct *alloc_uid(kuid_t uid) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 165 | { |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 166 | struct hlist_head *hashent = uidhashentry(uid); |
Pavel Emelyanov | 8eb703e | 2008-01-25 21:08:26 +0100 | [diff] [blame] | 167 | struct user_struct *up, *new; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 168 | |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 169 | spin_lock_irq(&uidhash_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 170 | up = uid_hash_find(uid, hashent); |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 171 | spin_unlock_irq(&uidhash_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 172 | |
| 173 | if (!up) { |
Andrew Morton | 354a1f4 | 2008-04-30 00:54:54 -0700 | [diff] [blame] | 174 | new = kmem_cache_zalloc(uid_cachep, GFP_KERNEL); |
Pavel Emelyanov | 8eb703e | 2008-01-25 21:08:26 +0100 | [diff] [blame] | 175 | if (!new) |
| 176 | goto out_unlock; |
Pavel Emelyanov | 5e8869b | 2007-11-26 21:21:49 +0100 | [diff] [blame] | 177 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 178 | new->uid = uid; |
| 179 | atomic_set(&new->__count, 1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 180 | |
| 181 | /* |
| 182 | * Before adding this, check whether we raced |
| 183 | * on adding the same user already.. |
| 184 | */ |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 185 | spin_lock_irq(&uidhash_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 186 | up = uid_hash_find(uid, hashent); |
| 187 | if (up) { |
| 188 | key_put(new->uid_keyring); |
| 189 | key_put(new->session_keyring); |
| 190 | kmem_cache_free(uid_cachep, new); |
| 191 | } else { |
| 192 | uid_hash_insert(new, hashent); |
| 193 | up = new; |
| 194 | } |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 195 | spin_unlock_irq(&uidhash_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 196 | } |
Dhaval Giani | 5cb350b | 2007-10-15 17:00:14 +0200 | [diff] [blame] | 197 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 198 | return up; |
Pavel Emelyanov | 8eb703e | 2008-01-25 21:08:26 +0100 | [diff] [blame] | 199 | |
Pavel Emelyanov | 8eb703e | 2008-01-25 21:08:26 +0100 | [diff] [blame] | 200 | out_unlock: |
Pavel Emelyanov | 8eb703e | 2008-01-25 21:08:26 +0100 | [diff] [blame] | 201 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 202 | } |
| 203 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 204 | static int __init uid_cache_init(void) |
| 205 | { |
| 206 | int n; |
| 207 | |
| 208 | uid_cachep = kmem_cache_create("uid_cache", sizeof(struct user_struct), |
Paul Mundt | 20c2df8 | 2007-07-20 10:11:58 +0900 | [diff] [blame] | 209 | 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 210 | |
| 211 | for(n = 0; n < UIDHASH_SZ; ++n) |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 212 | INIT_HLIST_HEAD(uidhash_table + n); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 213 | |
| 214 | /* Insert the root user immediately (init already runs as root) */ |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 215 | spin_lock_irq(&uidhash_lock); |
Eric W. Biederman | 7b44ab9 | 2011-11-16 23:20:58 -0800 | [diff] [blame] | 216 | uid_hash_insert(&root_user, uidhashentry(GLOBAL_ROOT_UID)); |
Andrew Morton | 3fa97c9 | 2006-01-31 16:34:26 -0800 | [diff] [blame] | 217 | spin_unlock_irq(&uidhash_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 218 | |
| 219 | return 0; |
| 220 | } |
| 221 | |
| 222 | module_init(uid_cache_init); |