security/keys/proc.c

   1 /* procfs files for key database enumeration
   2  *
   3  * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/sched.h>
  15 #include <linux/fs.h>
  16 #include <linux/proc_fs.h>
  17 #include <linux/seq_file.h>
  18 #include <asm/errno.h>
  19 #include "internal.h"
  20
  21 static int proc_keys_open(struct inode *inode, struct file *file);
  22 static void *proc_keys_start(struct seq_file *p, loff_t *_pos);
  23 static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos);
  24 static void proc_keys_stop(struct seq_file *p, void *v);
  25 static int proc_keys_show(struct seq_file *m, void *v);
  26
  27 static const struct seq_operations proc_keys_ops = {
  28         .start  = proc_keys_start,
  29         .next   = proc_keys_next,
  30         .stop   = proc_keys_stop,
  31         .show   = proc_keys_show,
  32 };
  33
  34 static const struct file_operations proc_keys_fops = {
  35         .open           = proc_keys_open,
  36         .read           = seq_read,
  37         .llseek         = seq_lseek,
  38         .release        = seq_release,
  39 };
  40
  41 static int proc_key_users_open(struct inode *inode, struct file *file);
  42 static void *proc_key_users_start(struct seq_file *p, loff_t *_pos);
  43 static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos);
  44 static void proc_key_users_stop(struct seq_file *p, void *v);
  45 static int proc_key_users_show(struct seq_file *m, void *v);
  46
  47 static const struct seq_operations proc_key_users_ops = {
  48         .start  = proc_key_users_start,
  49         .next   = proc_key_users_next,
  50         .stop   = proc_key_users_stop,
  51         .show   = proc_key_users_show,
  52 };
  53
  54 static const struct file_operations proc_key_users_fops = {
  55         .open           = proc_key_users_open,
  56         .read           = seq_read,
  57         .llseek         = seq_lseek,
  58         .release        = seq_release,
  59 };
  60
  61 /*
  62  * Declare the /proc files.
  63  */
  64 static int __init key_proc_init(void)
  65 {
  66         struct proc_dir_entry *p;
  67
  68         p = proc_create("keys", 0, NULL, &proc_keys_fops);
  69         if (!p)
  70                 panic("Cannot create /proc/keys\n");
  71
  72         p = proc_create("key-users", 0, NULL, &proc_key_users_fops);
  73         if (!p)
  74                 panic("Cannot create /proc/key-users\n");
  75
  76         return 0;
  77 }
  78
  79 __initcall(key_proc_init);
  80
  81 /*
  82  * Implement "/proc/keys" to provide a list of the keys on the system that
  83  * grant View permission to the caller.
  84  */
  85 static struct rb_node *key_serial_next(struct seq_file *p, struct rb_node *n)
  86 {
  87         struct user_namespace *user_ns = seq_user_ns(p);
  88
  89         n = rb_next(n);
  90         while (n) {
  91                 struct key *key = rb_entry(n, struct key, serial_node);
  92                 if (kuid_has_mapping(user_ns, key->user->uid))
  93                         break;
  94                 n = rb_next(n);
  95         }
  96         return n;
  97 }
  98
  99 static int proc_keys_open(struct inode *inode, struct file *file)
 100 {
 101         return seq_open(file, &proc_keys_ops);
 102 }
 103
 104 static struct key *find_ge_key(struct seq_file *p, key_serial_t id)
 105 {
 106         struct user_namespace *user_ns = seq_user_ns(p);
 107         struct rb_node *n = key_serial_tree.rb_node;
 108         struct key *minkey = NULL;
 109
 110         while (n) {
 111                 struct key *key = rb_entry(n, struct key, serial_node);
 112                 if (id < key->serial) {
 113                         if (!minkey || minkey->serial > key->serial)
 114                                 minkey = key;
 115                         n = n->rb_left;
 116                 } else if (id > key->serial) {
 117                         n = n->rb_right;
 118                 } else {
 119                         minkey = key;
 120                         break;
 121                 }
 122                 key = NULL;
 123         }
 124
 125         if (!minkey)
 126                 return NULL;
 127
 128         for (;;) {
 129                 if (kuid_has_mapping(user_ns, minkey->user->uid))
 130                         return minkey;
 131                 n = rb_next(&minkey->serial_node);
 132                 if (!n)
 133                         return NULL;
 134                 minkey = rb_entry(n, struct key, serial_node);
 135         }
 136 }
 137
 138 static void *proc_keys_start(struct seq_file *p, loff_t *_pos)
 139         __acquires(key_serial_lock)
 140 {
 141         key_serial_t pos = *_pos;
 142         struct key *key;
 143
 144         spin_lock(&key_serial_lock);
 145
 146         if (*_pos > INT_MAX)
 147                 return NULL;
 148         key = find_ge_key(p, pos);
 149         if (!key)
 150                 return NULL;
 151         *_pos = key->serial;
 152         return &key->serial_node;
 153 }
 154
 155 static inline key_serial_t key_node_serial(struct rb_node *n)
 156 {
 157         struct key *key = rb_entry(n, struct key, serial_node);
 158         return key->serial;
 159 }
 160
 161 static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos)
 162 {
 163         struct rb_node *n;
 164
 165         n = key_serial_next(p, v);
 166         if (n)
 167                 *_pos = key_node_serial(n);
 168         return n;
 169 }
 170
 171 static void proc_keys_stop(struct seq_file *p, void *v)
 172         __releases(key_serial_lock)
 173 {
 174         spin_unlock(&key_serial_lock);
 175 }
 176
 177 static int proc_keys_show(struct seq_file *m, void *v)
 178 {
 179         struct rb_node *_p = v;
 180         struct key *key = rb_entry(_p, struct key, serial_node);
 181         struct timespec now;
 182         unsigned long timo;
 183         key_ref_t key_ref, skey_ref;
 184         char xbuf[16];
 185         int rc;
 186
 187         struct keyring_search_context ctx = {
 188                 .index_key.type         = key->type,
 189                 .index_key.description  = key->description,
 190                 .cred                   = current_cred(),
 191                 .match_data.cmp         = lookup_user_key_possessed,
 192                 .match_data.raw_data    = key,
 193                 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
 194                 .flags                  = KEYRING_SEARCH_NO_STATE_CHECK,
 195         };
 196
 197         key_ref = make_key_ref(key, 0);
 198
 199         /* determine if the key is possessed by this process (a test we can
 200          * skip if the key does not indicate the possessor can view it
 201          */
 202         if (key->perm & KEY_POS_VIEW) {
 203                 skey_ref = search_my_process_keyrings(&ctx);
 204                 if (!IS_ERR(skey_ref)) {
 205                         key_ref_put(skey_ref);
 206                         key_ref = make_key_ref(key, 1);
 207                 }
 208         }
 209
 210         /* check whether the current task is allowed to view the key (assuming
 211          * non-possession)
 212          * - the caller holds a spinlock, and thus the RCU read lock, making our
 213          *   access to __current_cred() safe
 214          */
 215         rc = key_task_permission(key_ref, ctx.cred, KEY_NEED_VIEW);
 216         if (rc < 0)
 217                 return 0;
 218
 219         now = current_kernel_time();
 220
 221         rcu_read_lock();
 222
 223         /* come up with a suitable timeout value */
 224         if (key->expiry == 0) {
 225                 memcpy(xbuf, "perm", 5);
 226         } else if (now.tv_sec >= key->expiry) {
 227                 memcpy(xbuf, "expd", 5);
 228         } else {
 229                 timo = key->expiry - now.tv_sec;
 230
 231                 if (timo < 60)
 232                         sprintf(xbuf, "%lus", timo);
 233                 else if (timo < 60*60)
 234                         sprintf(xbuf, "%lum", timo / 60);
 235                 else if (timo < 60*60*24)
 236                         sprintf(xbuf, "%luh", timo / (60*60));
 237                 else if (timo < 60*60*24*7)
 238                         sprintf(xbuf, "%lud", timo / (60*60*24));
 239                 else
 240                         sprintf(xbuf, "%luw", timo / (60*60*24*7));
 241         }
 242
 243 #define showflag(KEY, LETTER, FLAG) \
 244         (test_bit(FLAG, &(KEY)->flags) ? LETTER : '-')
 245
 246         seq_printf(m, "%08x %c%c%c%c%c%c%c %5d %4s %08x %5d %5d %-9.9s ",
 247                    key->serial,
 248                    showflag(key, 'I', KEY_FLAG_INSTANTIATED),
 249                    showflag(key, 'R', KEY_FLAG_REVOKED),
 250                    showflag(key, 'D', KEY_FLAG_DEAD),
 251                    showflag(key, 'Q', KEY_FLAG_IN_QUOTA),
 252                    showflag(key, 'U', KEY_FLAG_USER_CONSTRUCT),
 253                    showflag(key, 'N', KEY_FLAG_NEGATIVE),
 254                    showflag(key, 'i', KEY_FLAG_INVALIDATED),
 255                    refcount_read(&key->usage),
 256                    xbuf,
 257                    key->perm,
 258                    from_kuid_munged(seq_user_ns(m), key->uid),
 259                    from_kgid_munged(seq_user_ns(m), key->gid),
 260                    key->type->name);
 261
 262 #undef showflag
 263
 264         if (key->type->describe)
 265                 key->type->describe(key, m);
 266         seq_putc(m, '\n');
 267
 268         rcu_read_unlock();
 269         return 0;
 270 }
 271
 272 static struct rb_node *__key_user_next(struct user_namespace *user_ns, struct rb_node *n)
 273 {
 274         while (n) {
 275                 struct key_user *user = rb_entry(n, struct key_user, node);
 276                 if (kuid_has_mapping(user_ns, user->uid))
 277                         break;
 278                 n = rb_next(n);
 279         }
 280         return n;
 281 }
 282
 283 static struct rb_node *key_user_next(struct user_namespace *user_ns, struct rb_node *n)
 284 {
 285         return __key_user_next(user_ns, rb_next(n));
 286 }
 287
 288 static struct rb_node *key_user_first(struct user_namespace *user_ns, struct rb_root *r)
 289 {
 290         struct rb_node *n = rb_first(r);
 291         return __key_user_next(user_ns, n);
 292 }
 293
 294 /*
 295  * Implement "/proc/key-users" to provides a list of the key users and their
 296  * quotas.
 297  */
 298 static int proc_key_users_open(struct inode *inode, struct file *file)
 299 {
 300         return seq_open(file, &proc_key_users_ops);
 301 }
 302
 303 static void *proc_key_users_start(struct seq_file *p, loff_t *_pos)
 304         __acquires(key_user_lock)
 305 {
 306         struct rb_node *_p;
 307         loff_t pos = *_pos;
 308
 309         spin_lock(&key_user_lock);
 310
 311         _p = key_user_first(seq_user_ns(p), &key_user_tree);
 312         while (pos > 0 && _p) {
 313                 pos--;
 314                 _p = key_user_next(seq_user_ns(p), _p);
 315         }
 316
 317         return _p;
 318 }
 319
 320 static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos)
 321 {
 322         (*_pos)++;
 323         return key_user_next(seq_user_ns(p), (struct rb_node *)v);
 324 }
 325
 326 static void proc_key_users_stop(struct seq_file *p, void *v)
 327         __releases(key_user_lock)
 328 {
 329         spin_unlock(&key_user_lock);
 330 }
 331
 332 static int proc_key_users_show(struct seq_file *m, void *v)
 333 {
 334         struct rb_node *_p = v;
 335         struct key_user *user = rb_entry(_p, struct key_user, node);
 336         unsigned maxkeys = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
 337                 key_quota_root_maxkeys : key_quota_maxkeys;
 338         unsigned maxbytes = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
 339                 key_quota_root_maxbytes : key_quota_maxbytes;
 340
 341         seq_printf(m, "%5u: %5d %d/%d %d/%d %d/%d\n",
 342                    from_kuid_munged(seq_user_ns(m), user->uid),
 343                    refcount_read(&user->usage),
 344                    atomic_read(&user->nkeys),
 345                    atomic_read(&user->nikeys),
 346                    user->qnkeys,
 347                    maxkeys,
 348                    user->qnbytes,
 349                    maxbytes);
 350
 351         return 0;
 352 }