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 void *proc_keys_start(struct seq_file *p, loff_t *_pos);
  22 static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos);
  23 static void proc_keys_stop(struct seq_file *p, void *v);
  24 static int proc_keys_show(struct seq_file *m, void *v);
  25
  26 static const struct seq_operations proc_keys_ops = {
  27         .start  = proc_keys_start,
  28         .next   = proc_keys_next,
  29         .stop   = proc_keys_stop,
  30         .show   = proc_keys_show,
  31 };
  32
  33 static void *proc_key_users_start(struct seq_file *p, loff_t *_pos);
  34 static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos);
  35 static void proc_key_users_stop(struct seq_file *p, void *v);
  36 static int proc_key_users_show(struct seq_file *m, void *v);
  37
  38 static const struct seq_operations proc_key_users_ops = {
  39         .start  = proc_key_users_start,
  40         .next   = proc_key_users_next,
  41         .stop   = proc_key_users_stop,
  42         .show   = proc_key_users_show,
  43 };
  44
  45 /*
  46  * Declare the /proc files.
  47  */
  48 static int __init key_proc_init(void)
  49 {
  50         struct proc_dir_entry *p;
  51
  52         p = proc_create_seq("keys", 0, NULL, &proc_keys_ops);
  53         if (!p)
  54                 panic("Cannot create /proc/keys\n");
  55
  56         p = proc_create_seq("key-users", 0, NULL, &proc_key_users_ops);
  57         if (!p)
  58                 panic("Cannot create /proc/key-users\n");
  59
  60         return 0;
  61 }
  62
  63 __initcall(key_proc_init);
  64
  65 /*
  66  * Implement "/proc/keys" to provide a list of the keys on the system that
  67  * grant View permission to the caller.
  68  */
  69 static struct rb_node *key_serial_next(struct seq_file *p, struct rb_node *n)
  70 {
  71         struct user_namespace *user_ns = seq_user_ns(p);
  72
  73         n = rb_next(n);
  74         while (n) {
  75                 struct key *key = rb_entry(n, struct key, serial_node);
  76                 if (kuid_has_mapping(user_ns, key->user->uid))
  77                         break;
  78                 n = rb_next(n);
  79         }
  80         return n;
  81 }
  82
  83 static struct key *find_ge_key(struct seq_file *p, key_serial_t id)
  84 {
  85         struct user_namespace *user_ns = seq_user_ns(p);
  86         struct rb_node *n = key_serial_tree.rb_node;
  87         struct key *minkey = NULL;
  88
  89         while (n) {
  90                 struct key *key = rb_entry(n, struct key, serial_node);
  91                 if (id < key->serial) {
  92                         if (!minkey || minkey->serial > key->serial)
  93                                 minkey = key;
  94                         n = n->rb_left;
  95                 } else if (id > key->serial) {
  96                         n = n->rb_right;
  97                 } else {
  98                         minkey = key;
  99                         break;
 100                 }
 101                 key = NULL;
 102         }
 103
 104         if (!minkey)
 105                 return NULL;
 106
 107         for (;;) {
 108                 if (kuid_has_mapping(user_ns, minkey->user->uid))
 109                         return minkey;
 110                 n = rb_next(&minkey->serial_node);
 111                 if (!n)
 112                         return NULL;
 113                 minkey = rb_entry(n, struct key, serial_node);
 114         }
 115 }
 116
 117 static void *proc_keys_start(struct seq_file *p, loff_t *_pos)
 118         __acquires(key_serial_lock)
 119 {
 120         key_serial_t pos = *_pos;
 121         struct key *key;
 122
 123         spin_lock(&key_serial_lock);
 124
 125         if (*_pos > INT_MAX)
 126                 return NULL;
 127         key = find_ge_key(p, pos);
 128         if (!key)
 129                 return NULL;
 130         *_pos = key->serial;
 131         return &key->serial_node;
 132 }
 133
 134 static inline key_serial_t key_node_serial(struct rb_node *n)
 135 {
 136         struct key *key = rb_entry(n, struct key, serial_node);
 137         return key->serial;
 138 }
 139
 140 static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos)
 141 {
 142         struct rb_node *n;
 143
 144         n = key_serial_next(p, v);
 145         if (n)
 146                 *_pos = key_node_serial(n);
 147         return n;
 148 }
 149
 150 static void proc_keys_stop(struct seq_file *p, void *v)
 151         __releases(key_serial_lock)
 152 {
 153         spin_unlock(&key_serial_lock);
 154 }
 155
 156 static int proc_keys_show(struct seq_file *m, void *v)
 157 {
 158         struct rb_node *_p = v;
 159         struct key *key = rb_entry(_p, struct key, serial_node);
 160         unsigned long flags;
 161         key_ref_t key_ref, skey_ref;
 162         time64_t now, expiry;
 163         char xbuf[16];
 164         short state;
 165         u64 timo;
 166         int rc;
 167
 168         struct keyring_search_context ctx = {
 169                 .index_key.type         = key->type,
 170                 .index_key.description  = key->description,
 171                 .cred                   = m->file->f_cred,
 172                 .match_data.cmp         = lookup_user_key_possessed,
 173                 .match_data.raw_data    = key,
 174                 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
 175                 .flags                  = KEYRING_SEARCH_NO_STATE_CHECK,
 176         };
 177
 178         key_ref = make_key_ref(key, 0);
 179
 180         /* determine if the key is possessed by this process (a test we can
 181          * skip if the key does not indicate the possessor can view it
 182          */
 183         if (key->perm & KEY_POS_VIEW) {
 184                 skey_ref = search_my_process_keyrings(&ctx);
 185                 if (!IS_ERR(skey_ref)) {
 186                         key_ref_put(skey_ref);
 187                         key_ref = make_key_ref(key, 1);
 188                 }
 189         }
 190
 191         /* check whether the current task is allowed to view the key */
 192         rc = key_task_permission(key_ref, ctx.cred, KEY_NEED_VIEW);
 193         if (rc < 0)
 194                 return 0;
 195
 196         now = ktime_get_real_seconds();
 197
 198         rcu_read_lock();
 199
 200         /* come up with a suitable timeout value */
 201         expiry = READ_ONCE(key->expiry);
 202         if (expiry == 0) {
 203                 memcpy(xbuf, "perm", 5);
 204         } else if (now >= expiry) {
 205                 memcpy(xbuf, "expd", 5);
 206         } else {
 207                 timo = expiry - now;
 208
 209                 if (timo < 60)
 210                         sprintf(xbuf, "%llus", timo);
 211                 else if (timo < 60*60)
 212                         sprintf(xbuf, "%llum", div_u64(timo, 60));
 213                 else if (timo < 60*60*24)
 214                         sprintf(xbuf, "%lluh", div_u64(timo, 60 * 60));
 215                 else if (timo < 60*60*24*7)
 216                         sprintf(xbuf, "%llud", div_u64(timo, 60 * 60 * 24));
 217                 else
 218                         sprintf(xbuf, "%lluw", div_u64(timo, 60 * 60 * 24 * 7));
 219         }
 220
 221         state = key_read_state(key);
 222
 223 #define showflag(FLAGS, LETTER, FLAG) \
 224         ((FLAGS & (1 << FLAG)) ? LETTER : '-')
 225
 226         flags = READ_ONCE(key->flags);
 227         seq_printf(m, "%08x %c%c%c%c%c%c%c %5d %4s %08x %5d %5d %-9.9s ",
 228                    key->serial,
 229                    state != KEY_IS_UNINSTANTIATED ? 'I' : '-',
 230                    showflag(flags, 'R', KEY_FLAG_REVOKED),
 231                    showflag(flags, 'D', KEY_FLAG_DEAD),
 232                    showflag(flags, 'Q', KEY_FLAG_IN_QUOTA),
 233                    showflag(flags, 'U', KEY_FLAG_USER_CONSTRUCT),
 234                    state < 0 ? 'N' : '-',
 235                    showflag(flags, 'i', KEY_FLAG_INVALIDATED),
 236                    refcount_read(&key->usage),
 237                    xbuf,
 238                    key->perm,
 239                    from_kuid_munged(seq_user_ns(m), key->uid),
 240                    from_kgid_munged(seq_user_ns(m), key->gid),
 241                    key->type->name);
 242
 243 #undef showflag
 244
 245         if (key->type->describe)
 246                 key->type->describe(key, m);
 247         seq_putc(m, '\n');
 248
 249         rcu_read_unlock();
 250         return 0;
 251 }
 252
 253 static struct rb_node *__key_user_next(struct user_namespace *user_ns, struct rb_node *n)
 254 {
 255         while (n) {
 256                 struct key_user *user = rb_entry(n, struct key_user, node);
 257                 if (kuid_has_mapping(user_ns, user->uid))
 258                         break;
 259                 n = rb_next(n);
 260         }
 261         return n;
 262 }
 263
 264 static struct rb_node *key_user_next(struct user_namespace *user_ns, struct rb_node *n)
 265 {
 266         return __key_user_next(user_ns, rb_next(n));
 267 }
 268
 269 static struct rb_node *key_user_first(struct user_namespace *user_ns, struct rb_root *r)
 270 {
 271         struct rb_node *n = rb_first(r);
 272         return __key_user_next(user_ns, n);
 273 }
 274
 275 static void *proc_key_users_start(struct seq_file *p, loff_t *_pos)
 276         __acquires(key_user_lock)
 277 {
 278         struct rb_node *_p;
 279         loff_t pos = *_pos;
 280
 281         spin_lock(&key_user_lock);
 282
 283         _p = key_user_first(seq_user_ns(p), &key_user_tree);
 284         while (pos > 0 && _p) {
 285                 pos--;
 286                 _p = key_user_next(seq_user_ns(p), _p);
 287         }
 288
 289         return _p;
 290 }
 291
 292 static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos)
 293 {
 294         (*_pos)++;
 295         return key_user_next(seq_user_ns(p), (struct rb_node *)v);
 296 }
 297
 298 static void proc_key_users_stop(struct seq_file *p, void *v)
 299         __releases(key_user_lock)
 300 {
 301         spin_unlock(&key_user_lock);
 302 }
 303
 304 static int proc_key_users_show(struct seq_file *m, void *v)
 305 {
 306         struct rb_node *_p = v;
 307         struct key_user *user = rb_entry(_p, struct key_user, node);
 308         unsigned maxkeys = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
 309                 key_quota_root_maxkeys : key_quota_maxkeys;
 310         unsigned maxbytes = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
 311                 key_quota_root_maxbytes : key_quota_maxbytes;
 312
 313         seq_printf(m, "%5u: %5d %d/%d %d/%d %d/%d\n",
 314                    from_kuid_munged(seq_user_ns(m), user->uid),
 315                    refcount_read(&user->usage),
 316                    atomic_read(&user->nkeys),
 317                    atomic_read(&user->nikeys),
 318                    user->qnkeys,
 319                    maxkeys,
 320                    user->qnbytes,
 321                    maxbytes);
 322
 323         return 0;
 324 }