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 #ifdef CONFIG_KEYS_DEBUG_PROC_KEYS
  22 static int proc_keys_open(struct inode *inode, struct file *file);
  23 static void *proc_keys_start(struct seq_file *p, loff_t *_pos);
  24 static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos);
  25 static void proc_keys_stop(struct seq_file *p, void *v);
  26 static int proc_keys_show(struct seq_file *m, void *v);
  27
  28 static const struct seq_operations proc_keys_ops = {
  29         .start  = proc_keys_start,
  30         .next   = proc_keys_next,
  31         .stop   = proc_keys_stop,
  32         .show   = proc_keys_show,
  33 };
  34
  35 static const struct file_operations proc_keys_fops = {
  36         .open           = proc_keys_open,
  37         .read           = seq_read,
  38         .llseek         = seq_lseek,
  39         .release        = seq_release,
  40 };
  41 #endif
  42
  43 static int proc_key_users_open(struct inode *inode, struct file *file);
  44 static void *proc_key_users_start(struct seq_file *p, loff_t *_pos);
  45 static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos);
  46 static void proc_key_users_stop(struct seq_file *p, void *v);
  47 static int proc_key_users_show(struct seq_file *m, void *v);
  48
  49 static const struct seq_operations proc_key_users_ops = {
  50         .start  = proc_key_users_start,
  51         .next   = proc_key_users_next,
  52         .stop   = proc_key_users_stop,
  53         .show   = proc_key_users_show,
  54 };
  55
  56 static const struct file_operations proc_key_users_fops = {
  57         .open           = proc_key_users_open,
  58         .read           = seq_read,
  59         .llseek         = seq_lseek,
  60         .release        = seq_release,
  61 };
  62
  63 /*
  64  * Declare the /proc files.
  65  */
  66 static int __init key_proc_init(void)
  67 {
  68         struct proc_dir_entry *p;
  69
  70 #ifdef CONFIG_KEYS_DEBUG_PROC_KEYS
  71         p = proc_create("keys", 0, NULL, &proc_keys_fops);
  72         if (!p)
  73                 panic("Cannot create /proc/keys\n");
  74 #endif
  75
  76         p = proc_create("key-users", 0, NULL, &proc_key_users_fops);
  77         if (!p)
  78                 panic("Cannot create /proc/key-users\n");
  79
  80         return 0;
  81 }
  82
  83 __initcall(key_proc_init);
  84
  85 /*
  86  * Implement "/proc/keys" to provide a list of the keys on the system that
  87  * grant View permission to the caller.
  88  */
  89 #ifdef CONFIG_KEYS_DEBUG_PROC_KEYS
  90
  91 static struct rb_node *key_serial_next(struct seq_file *p, struct rb_node *n)
  92 {
  93         struct user_namespace *user_ns = seq_user_ns(p);
  94
  95         n = rb_next(n);
  96         while (n) {
  97                 struct key *key = rb_entry(n, struct key, serial_node);
  98                 if (kuid_has_mapping(user_ns, key->user->uid))
  99                         break;
 100                 n = rb_next(n);
 101         }
 102         return n;
 103 }
 104
 105 static int proc_keys_open(struct inode *inode, struct file *file)
 106 {
 107         return seq_open(file, &proc_keys_ops);
 108 }
 109
 110 static struct key *find_ge_key(struct seq_file *p, key_serial_t id)
 111 {
 112         struct user_namespace *user_ns = seq_user_ns(p);
 113         struct rb_node *n = key_serial_tree.rb_node;
 114         struct key *minkey = NULL;
 115
 116         while (n) {
 117                 struct key *key = rb_entry(n, struct key, serial_node);
 118                 if (id < key->serial) {
 119                         if (!minkey || minkey->serial > key->serial)
 120                                 minkey = key;
 121                         n = n->rb_left;
 122                 } else if (id > key->serial) {
 123                         n = n->rb_right;
 124                 } else {
 125                         minkey = key;
 126                         break;
 127                 }
 128                 key = NULL;
 129         }
 130
 131         if (!minkey)
 132                 return NULL;
 133
 134         for (;;) {
 135                 if (kuid_has_mapping(user_ns, minkey->user->uid))
 136                         return minkey;
 137                 n = rb_next(&minkey->serial_node);
 138                 if (!n)
 139                         return NULL;
 140                 minkey = rb_entry(n, struct key, serial_node);
 141         }
 142 }
 143
 144 static void *proc_keys_start(struct seq_file *p, loff_t *_pos)
 145         __acquires(key_serial_lock)
 146 {
 147         key_serial_t pos = *_pos;
 148         struct key *key;
 149
 150         spin_lock(&key_serial_lock);
 151
 152         if (*_pos > INT_MAX)
 153                 return NULL;
 154         key = find_ge_key(p, pos);
 155         if (!key)
 156                 return NULL;
 157         *_pos = key->serial;
 158         return &key->serial_node;
 159 }
 160
 161 static inline key_serial_t key_node_serial(struct rb_node *n)
 162 {
 163         struct key *key = rb_entry(n, struct key, serial_node);
 164         return key->serial;
 165 }
 166
 167 static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos)
 168 {
 169         struct rb_node *n;
 170
 171         n = key_serial_next(p, v);
 172         if (n)
 173                 *_pos = key_node_serial(n);
 174         return n;
 175 }
 176
 177 static void proc_keys_stop(struct seq_file *p, void *v)
 178         __releases(key_serial_lock)
 179 {
 180         spin_unlock(&key_serial_lock);
 181 }
 182
 183 static int proc_keys_show(struct seq_file *m, void *v)
 184 {
 185         const struct cred *cred = current_cred();
 186         struct rb_node *_p = v;
 187         struct key *key = rb_entry(_p, struct key, serial_node);
 188         struct timespec now;
 189         unsigned long timo;
 190         key_ref_t key_ref, skey_ref;
 191         char xbuf[12];
 192         int rc;
 193
 194         key_ref = make_key_ref(key, 0);
 195
 196         /* determine if the key is possessed by this process (a test we can
 197          * skip if the key does not indicate the possessor can view it
 198          */
 199         if (key->perm & KEY_POS_VIEW) {
 200                 skey_ref = search_my_process_keyrings(key->type, key,
 201                                                       lookup_user_key_possessed,
 202                                                       true, cred);
 203                 if (!IS_ERR(skey_ref)) {
 204                         key_ref_put(skey_ref);
 205                         key_ref = make_key_ref(key, 1);
 206                 }
 207         }
 208
 209         /* check whether the current task is allowed to view the key (assuming
 210          * non-possession)
 211          * - the caller holds a spinlock, and thus the RCU read lock, making our
 212          *   access to __current_cred() safe
 213          */
 214         rc = key_task_permission(key_ref, cred, KEY_VIEW);
 215         if (rc < 0)
 216                 return 0;
 217
 218         now = current_kernel_time();
 219
 220         rcu_read_lock();
 221
 222         /* come up with a suitable timeout value */
 223         if (key->expiry == 0) {
 224                 memcpy(xbuf, "perm", 5);
 225         } else if (now.tv_sec >= key->expiry) {
 226                 memcpy(xbuf, "expd", 5);
 227         } else {
 228                 timo = key->expiry - now.tv_sec;
 229
 230                 if (timo < 60)
 231                         sprintf(xbuf, "%lus", timo);
 232                 else if (timo < 60*60)
 233                         sprintf(xbuf, "%lum", timo / 60);
 234                 else if (timo < 60*60*24)
 235                         sprintf(xbuf, "%luh", timo / (60*60));
 236                 else if (timo < 60*60*24*7)
 237                         sprintf(xbuf, "%lud", timo / (60*60*24));
 238                 else
 239                         sprintf(xbuf, "%luw", timo / (60*60*24*7));
 240         }
 241
 242 #define showflag(KEY, LETTER, FLAG) \
 243         (test_bit(FLAG, &(KEY)->flags) ? LETTER : '-')
 244
 245         seq_printf(m, "%08x %c%c%c%c%c%c%c %5d %4s %08x %5d %5d %-9.9s ",
 246                    key->serial,
 247                    showflag(key, 'I', KEY_FLAG_INSTANTIATED),
 248                    showflag(key, 'R', KEY_FLAG_REVOKED),
 249                    showflag(key, 'D', KEY_FLAG_DEAD),
 250                    showflag(key, 'Q', KEY_FLAG_IN_QUOTA),
 251                    showflag(key, 'U', KEY_FLAG_USER_CONSTRUCT),
 252                    showflag(key, 'N', KEY_FLAG_NEGATIVE),
 253                    showflag(key, 'i', KEY_FLAG_INVALIDATED),
 254                    atomic_read(&key->usage),
 255                    xbuf,
 256                    key->perm,
 257                    from_kuid_munged(seq_user_ns(m), key->uid),
 258                    from_kgid_munged(seq_user_ns(m), key->gid),
 259                    key->type->name);
 260
 261 #undef showflag
 262
 263         if (key->type->describe)
 264                 key->type->describe(key, m);
 265         seq_putc(m, '\n');
 266
 267         rcu_read_unlock();
 268         return 0;
 269 }
 270
 271 #endif /* CONFIG_KEYS_DEBUG_PROC_KEYS */
 272
 273 static struct rb_node *__key_user_next(struct user_namespace *user_ns, struct rb_node *n)
 274 {
 275         while (n) {
 276                 struct key_user *user = rb_entry(n, struct key_user, node);
 277                 if (kuid_has_mapping(user_ns, user->uid))
 278                         break;
 279                 n = rb_next(n);
 280         }
 281         return n;
 282 }
 283
 284 static struct rb_node *key_user_next(struct user_namespace *user_ns, struct rb_node *n)
 285 {
 286         return __key_user_next(user_ns, rb_next(n));
 287 }
 288
 289 static struct rb_node *key_user_first(struct user_namespace *user_ns, struct rb_root *r)
 290 {
 291         struct rb_node *n = rb_first(r);
 292         return __key_user_next(user_ns, n);
 293 }
 294
 295 /*
 296  * Implement "/proc/key-users" to provides a list of the key users and their
 297  * quotas.
 298  */
 299 static int proc_key_users_open(struct inode *inode, struct file *file)
 300 {
 301         return seq_open(file, &proc_key_users_ops);
 302 }
 303
 304 static void *proc_key_users_start(struct seq_file *p, loff_t *_pos)
 305         __acquires(key_user_lock)
 306 {
 307         struct rb_node *_p;
 308         loff_t pos = *_pos;
 309
 310         spin_lock(&key_user_lock);
 311
 312         _p = key_user_first(seq_user_ns(p), &key_user_tree);
 313         while (pos > 0 && _p) {
 314                 pos--;
 315                 _p = key_user_next(seq_user_ns(p), _p);
 316         }
 317
 318         return _p;
 319 }
 320
 321 static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos)
 322 {
 323         (*_pos)++;
 324         return key_user_next(seq_user_ns(p), (struct rb_node *)v);
 325 }
 326
 327 static void proc_key_users_stop(struct seq_file *p, void *v)
 328         __releases(key_user_lock)
 329 {
 330         spin_unlock(&key_user_lock);
 331 }
 332
 333 static int proc_key_users_show(struct seq_file *m, void *v)
 334 {
 335         struct rb_node *_p = v;
 336         struct key_user *user = rb_entry(_p, struct key_user, node);
 337         unsigned maxkeys = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
 338                 key_quota_root_maxkeys : key_quota_maxkeys;
 339         unsigned maxbytes = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
 340                 key_quota_root_maxbytes : key_quota_maxbytes;
 341
 342         seq_printf(m, "%5u: %5d %d/%d %d/%d %d/%d\n",
 343                    from_kuid_munged(seq_user_ns(m), user->uid),
 344                    atomic_read(&user->usage),
 345                    atomic_read(&user->nkeys),
 346                    atomic_read(&user->nikeys),
 347                    user->qnkeys,
 348                    maxkeys,
 349                    user->qnbytes,
 350                    maxbytes);
 351
 352         return 0;
 353 }