net/rxrpc/ar-key.c

   1 /* RxRPC key management
   2  *
   3  * Copyright (C) 2007 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  * RxRPC keys should have a description of describing their purpose:
  12  *      "afs@CAMBRIDGE.REDHAT.COM>
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/net.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/key.h>
  19 #include <linux/crypto.h>
  20 #include <net/sock.h>
  21 #include <net/af_rxrpc.h>
  22 #include <keys/rxrpc-type.h>
  23 #include <keys/user-type.h>
  24 #include "ar-internal.h"
  25
  26 static int rxrpc_instantiate(struct key *, const void *, size_t);
  27 static int rxrpc_instantiate_s(struct key *, const void *, size_t);
  28 static void rxrpc_destroy(struct key *);
  29 static void rxrpc_destroy_s(struct key *);
  30 static void rxrpc_describe(const struct key *, struct seq_file *);
  31
  32 /*
  33  * rxrpc defined keys take an arbitrary string as the description and an
  34  * arbitrary blob of data as the payload
  35  */
  36 struct key_type key_type_rxrpc = {
  37         .name           = "rxrpc",
  38         .instantiate    = rxrpc_instantiate,
  39         .match          = user_match,
  40         .destroy        = rxrpc_destroy,
  41         .describe       = rxrpc_describe,
  42 };
  43
  44 EXPORT_SYMBOL(key_type_rxrpc);
  45
  46 /*
  47  * rxrpc server defined keys take "<serviceId>:<securityIndex>" as the
  48  * description and an 8-byte decryption key as the payload
  49  */
  50 struct key_type key_type_rxrpc_s = {
  51         .name           = "rxrpc_s",
  52         .instantiate    = rxrpc_instantiate_s,
  53         .match          = user_match,
  54         .destroy        = rxrpc_destroy_s,
  55         .describe       = rxrpc_describe,
  56 };
  57
  58 /*
  59  * instantiate an rxrpc defined key
  60  * data should be of the form:
  61  *      OFFSET  LEN     CONTENT
  62  *      0       4       key interface version number
  63  *      4       2       security index (type)
  64  *      6       2       ticket length
  65  *      8       4       key expiry time (time_t)
  66  *      12      4       kvno
  67  *      16      8       session key
  68  *      24      [len]   ticket
  69  *
  70  * if no data is provided, then a no-security key is made
  71  */
  72 static int rxrpc_instantiate(struct key *key, const void *data, size_t datalen)
  73 {
  74         const struct rxkad_key *tsec;
  75         struct rxrpc_key_payload *upayload;
  76         size_t plen;
  77         u32 kver;
  78         int ret;
  79
  80         _enter("{%x},,%zu", key_serial(key), datalen);
  81
  82         /* handle a no-security key */
  83         if (!data && datalen == 0)
  84                 return 0;
  85
  86         /* get the key interface version number */
  87         ret = -EINVAL;
  88         if (datalen <= 4 || !data)
  89                 goto error;
  90         memcpy(&kver, data, sizeof(kver));
  91         data += sizeof(kver);
  92         datalen -= sizeof(kver);
  93
  94         _debug("KEY I/F VERSION: %u", kver);
  95
  96         ret = -EKEYREJECTED;
  97         if (kver != 1)
  98                 goto error;
  99
 100         /* deal with a version 1 key */
 101         ret = -EINVAL;
 102         if (datalen < sizeof(*tsec))
 103                 goto error;
 104
 105         tsec = data;
 106         if (datalen != sizeof(*tsec) + tsec->ticket_len)
 107                 goto error;
 108
 109         _debug("SCIX: %u", tsec->security_index);
 110         _debug("TLEN: %u", tsec->ticket_len);
 111         _debug("EXPY: %x", tsec->expiry);
 112         _debug("KVNO: %u", tsec->kvno);
 113         _debug("SKEY: %02x%02x%02x%02x%02x%02x%02x%02x",
 114                tsec->session_key[0], tsec->session_key[1],
 115                tsec->session_key[2], tsec->session_key[3],
 116                tsec->session_key[4], tsec->session_key[5],
 117                tsec->session_key[6], tsec->session_key[7]);
 118         if (tsec->ticket_len >= 8)
 119                 _debug("TCKT: %02x%02x%02x%02x%02x%02x%02x%02x",
 120                        tsec->ticket[0], tsec->ticket[1],
 121                        tsec->ticket[2], tsec->ticket[3],
 122                        tsec->ticket[4], tsec->ticket[5],
 123                        tsec->ticket[6], tsec->ticket[7]);
 124
 125         ret = -EPROTONOSUPPORT;
 126         if (tsec->security_index != 2)
 127                 goto error;
 128
 129         key->type_data.x[0] = tsec->security_index;
 130
 131         plen = sizeof(*upayload) + tsec->ticket_len;
 132         ret = key_payload_reserve(key, plen);
 133         if (ret < 0)
 134                 goto error;
 135
 136         ret = -ENOMEM;
 137         upayload = kmalloc(plen, GFP_KERNEL);
 138         if (!upayload)
 139                 goto error;
 140
 141         /* attach the data */
 142         memcpy(&upayload->k, tsec, sizeof(*tsec));
 143         memcpy(&upayload->k.ticket, (void *)tsec + sizeof(*tsec),
 144                tsec->ticket_len);
 145         key->payload.data = upayload;
 146         key->expiry = tsec->expiry;
 147         ret = 0;
 148
 149 error:
 150         return ret;
 151 }
 152
 153 /*
 154  * instantiate a server secret key
 155  * data should be a pointer to the 8-byte secret key
 156  */
 157 static int rxrpc_instantiate_s(struct key *key, const void *data,
 158                                size_t datalen)
 159 {
 160         struct crypto_blkcipher *ci;
 161
 162         _enter("{%x},,%zu", key_serial(key), datalen);
 163
 164         if (datalen != 8)
 165                 return -EINVAL;
 166
 167         memcpy(&key->type_data, data, 8);
 168
 169         ci = crypto_alloc_blkcipher("pcbc(des)", 0, CRYPTO_ALG_ASYNC);
 170         if (IS_ERR(ci)) {
 171                 _leave(" = %ld", PTR_ERR(ci));
 172                 return PTR_ERR(ci);
 173         }
 174
 175         if (crypto_blkcipher_setkey(ci, data, 8) < 0)
 176                 BUG();
 177
 178         key->payload.data = ci;
 179         _leave(" = 0");
 180         return 0;
 181 }
 182
 183 /*
 184  * dispose of the data dangling from the corpse of a rxrpc key
 185  */
 186 static void rxrpc_destroy(struct key *key)
 187 {
 188         kfree(key->payload.data);
 189 }
 190
 191 /*
 192  * dispose of the data dangling from the corpse of a rxrpc key
 193  */
 194 static void rxrpc_destroy_s(struct key *key)
 195 {
 196         if (key->payload.data) {
 197                 crypto_free_blkcipher(key->payload.data);
 198                 key->payload.data = NULL;
 199         }
 200 }
 201
 202 /*
 203  * describe the rxrpc key
 204  */
 205 static void rxrpc_describe(const struct key *key, struct seq_file *m)
 206 {
 207         seq_puts(m, key->description);
 208 }
 209
 210 /*
 211  * grab the security key for a socket
 212  */
 213 int rxrpc_request_key(struct rxrpc_sock *rx, char __user *optval, int optlen)
 214 {
 215         struct key *key;
 216         char *description;
 217
 218         _enter("");
 219
 220         if (optlen <= 0 || optlen > PAGE_SIZE - 1)
 221                 return -EINVAL;
 222
 223         description = kmalloc(optlen + 1, GFP_KERNEL);
 224         if (!description)
 225                 return -ENOMEM;
 226
 227         if (copy_from_user(description, optval, optlen)) {
 228                 kfree(description);
 229                 return -EFAULT;
 230         }
 231         description[optlen] = 0;
 232
 233         key = request_key(&key_type_rxrpc, description, NULL);
 234         if (IS_ERR(key)) {
 235                 kfree(description);
 236                 _leave(" = %ld", PTR_ERR(key));
 237                 return PTR_ERR(key);
 238         }
 239
 240         rx->key = key;
 241         kfree(description);
 242         _leave(" = 0 [key %x]", key->serial);
 243         return 0;
 244 }
 245
 246 /*
 247  * grab the security keyring for a server socket
 248  */
 249 int rxrpc_server_keyring(struct rxrpc_sock *rx, char __user *optval,
 250                          int optlen)
 251 {
 252         struct key *key;
 253         char *description;
 254
 255         _enter("");
 256
 257         if (optlen <= 0 || optlen > PAGE_SIZE - 1)
 258                 return -EINVAL;
 259
 260         description = kmalloc(optlen + 1, GFP_KERNEL);
 261         if (!description)
 262                 return -ENOMEM;
 263
 264         if (copy_from_user(description, optval, optlen)) {
 265                 kfree(description);
 266                 return -EFAULT;
 267         }
 268         description[optlen] = 0;
 269
 270         key = request_key(&key_type_keyring, description, NULL);
 271         if (IS_ERR(key)) {
 272                 kfree(description);
 273                 _leave(" = %ld", PTR_ERR(key));
 274                 return PTR_ERR(key);
 275         }
 276
 277         rx->securities = key;
 278         kfree(description);
 279         _leave(" = 0 [key %x]", key->serial);
 280         return 0;
 281 }
 282
 283 /*
 284  * generate a server data key
 285  */
 286 int rxrpc_get_server_data_key(struct rxrpc_connection *conn,
 287                               const void *session_key,
 288                               time_t expiry,
 289                               u32 kvno)
 290 {
 291         struct key *key;
 292         int ret;
 293
 294         struct {
 295                 u32 kver;
 296                 struct rxkad_key tsec;
 297         } data;
 298
 299         _enter("");
 300
 301         key = key_alloc(&key_type_rxrpc, "x", 0, 0, current, 0,
 302                         KEY_ALLOC_NOT_IN_QUOTA);
 303         if (IS_ERR(key)) {
 304                 _leave(" = -ENOMEM [alloc %ld]", PTR_ERR(key));
 305                 return -ENOMEM;
 306         }
 307
 308         _debug("key %d", key_serial(key));
 309
 310         data.kver = 1;
 311         data.tsec.security_index = 2;
 312         data.tsec.ticket_len = 0;
 313         data.tsec.expiry = expiry;
 314         data.tsec.kvno = 0;
 315
 316         memcpy(&data.tsec.session_key, session_key,
 317                sizeof(data.tsec.session_key));
 318
 319         ret = key_instantiate_and_link(key, &data, sizeof(data), NULL, NULL);
 320         if (ret < 0)
 321                 goto error;
 322
 323         conn->key = key;
 324         _leave(" = 0 [%d]", key_serial(key));
 325         return 0;
 326
 327 error:
 328         key_revoke(key);
 329         key_put(key);
 330         _leave(" = -ENOMEM [ins %d]", ret);
 331         return -ENOMEM;
 332 }
 333
 334 EXPORT_SYMBOL(rxrpc_get_server_data_key);