net/rxrpc/rxkad.c

   1 /* Kerberos-based RxRPC security
   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
  12 #include <crypto/skcipher.h>
  13 #include <linux/module.h>
  14 #include <linux/net.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/udp.h>
  17 #include <linux/scatterlist.h>
  18 #include <linux/ctype.h>
  19 #include <linux/slab.h>
  20 #include <net/sock.h>
  21 #include <net/af_rxrpc.h>
  22 #include <keys/rxrpc-type.h>
  23 #define rxrpc_debug rxkad_debug
  24 #include "ar-internal.h"
  25
  26 #define RXKAD_VERSION                   2
  27 #define MAXKRB5TICKETLEN                1024
  28 #define RXKAD_TKT_TYPE_KERBEROS_V5      256
  29 #define ANAME_SZ                        40      /* size of authentication name */
  30 #define INST_SZ                         40      /* size of principal's instance */
  31 #define REALM_SZ                        40      /* size of principal's auth domain */
  32 #define SNAME_SZ                        40      /* size of service name */
  33
  34 unsigned int rxrpc_debug;
  35 module_param_named(debug, rxrpc_debug, uint, S_IWUSR | S_IRUGO);
  36 MODULE_PARM_DESC(debug, "rxkad debugging mask");
  37
  38 struct rxkad_level1_hdr {
  39         __be32  data_size;      /* true data size (excluding padding) */
  40 };
  41
  42 struct rxkad_level2_hdr {
  43         __be32  data_size;      /* true data size (excluding padding) */
  44         __be32  checksum;       /* decrypted data checksum */
  45 };
  46
  47 MODULE_DESCRIPTION("RxRPC network protocol type-2 security (Kerberos 4)");
  48 MODULE_AUTHOR("Red Hat, Inc.");
  49 MODULE_LICENSE("GPL");
  50
  51 /*
  52  * this holds a pinned cipher so that keventd doesn't get called by the cipher
  53  * alloc routine, but since we have it to hand, we use it to decrypt RESPONSE
  54  * packets
  55  */
  56 static struct crypto_skcipher *rxkad_ci;
  57 static DEFINE_MUTEX(rxkad_ci_mutex);
  58
  59 /*
  60  * initialise connection security
  61  */
  62 static int rxkad_init_connection_security(struct rxrpc_connection *conn)
  63 {
  64         struct crypto_skcipher *ci;
  65         struct rxrpc_key_token *token;
  66         int ret;
  67
  68         _enter("{%d},{%x}", conn->debug_id, key_serial(conn->key));
  69
  70         token = conn->key->payload.data[0];
  71         conn->security_ix = token->security_index;
  72
  73         ci = crypto_alloc_skcipher("pcbc(fcrypt)", 0, CRYPTO_ALG_ASYNC);
  74         if (IS_ERR(ci)) {
  75                 _debug("no cipher");
  76                 ret = PTR_ERR(ci);
  77                 goto error;
  78         }
  79
  80         if (crypto_skcipher_setkey(ci, token->kad->session_key,
  81                                    sizeof(token->kad->session_key)) < 0)
  82                 BUG();
  83
  84         switch (conn->security_level) {
  85         case RXRPC_SECURITY_PLAIN:
  86                 break;
  87         case RXRPC_SECURITY_AUTH:
  88                 conn->size_align = 8;
  89                 conn->security_size = sizeof(struct rxkad_level1_hdr);
  90                 conn->header_size += sizeof(struct rxkad_level1_hdr);
  91                 break;
  92         case RXRPC_SECURITY_ENCRYPT:
  93                 conn->size_align = 8;
  94                 conn->security_size = sizeof(struct rxkad_level2_hdr);
  95                 conn->header_size += sizeof(struct rxkad_level2_hdr);
  96                 break;
  97         default:
  98                 ret = -EKEYREJECTED;
  99                 goto error;
 100         }
 101
 102         conn->cipher = ci;
 103         ret = 0;
 104 error:
 105         _leave(" = %d", ret);
 106         return ret;
 107 }
 108
 109 /*
 110  * prime the encryption state with the invariant parts of a connection's
 111  * description
 112  */
 113 static void rxkad_prime_packet_security(struct rxrpc_connection *conn)
 114 {
 115         struct rxrpc_key_token *token;
 116         SKCIPHER_REQUEST_ON_STACK(req, conn->cipher);
 117         struct scatterlist sg[2];
 118         struct rxrpc_crypt iv;
 119         struct {
 120                 __be32 x[4];
 121         } tmpbuf __attribute__((aligned(16))); /* must all be in same page */
 122
 123         _enter("");
 124
 125         if (!conn->key)
 126                 return;
 127
 128         token = conn->key->payload.data[0];
 129         memcpy(&iv, token->kad->session_key, sizeof(iv));
 130
 131         tmpbuf.x[0] = conn->epoch;
 132         tmpbuf.x[1] = conn->cid;
 133         tmpbuf.x[2] = 0;
 134         tmpbuf.x[3] = htonl(conn->security_ix);
 135
 136         sg_init_one(&sg[0], &tmpbuf, sizeof(tmpbuf));
 137         sg_init_one(&sg[1], &tmpbuf, sizeof(tmpbuf));
 138
 139         skcipher_request_set_tfm(req, conn->cipher);
 140         skcipher_request_set_callback(req, 0, NULL, NULL);
 141         skcipher_request_set_crypt(req, &sg[1], &sg[0], sizeof(tmpbuf), iv.x);
 142
 143         crypto_skcipher_encrypt(req);
 144         skcipher_request_zero(req);
 145
 146         memcpy(&conn->csum_iv, &tmpbuf.x[2], sizeof(conn->csum_iv));
 147         ASSERTCMP(conn->csum_iv.n[0], ==, tmpbuf.x[2]);
 148
 149         _leave("");
 150 }
 151
 152 /*
 153  * partially encrypt a packet (level 1 security)
 154  */
 155 static int rxkad_secure_packet_auth(const struct rxrpc_call *call,
 156                                     struct sk_buff *skb,
 157                                     u32 data_size,
 158                                     void *sechdr)
 159 {
 160         struct rxrpc_skb_priv *sp;
 161         SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
 162         struct rxrpc_crypt iv;
 163         struct scatterlist sg[2];
 164         struct {
 165                 struct rxkad_level1_hdr hdr;
 166                 __be32  first;  /* first four bytes of data and padding */
 167         } tmpbuf __attribute__((aligned(8))); /* must all be in same page */
 168         u16 check;
 169
 170         sp = rxrpc_skb(skb);
 171
 172         _enter("");
 173
 174         check = ntohl(sp->hdr.seq ^ sp->hdr.callNumber);
 175         data_size |= (u32) check << 16;
 176
 177         tmpbuf.hdr.data_size = htonl(data_size);
 178         memcpy(&tmpbuf.first, sechdr + 4, sizeof(tmpbuf.first));
 179
 180         /* start the encryption afresh */
 181         memset(&iv, 0, sizeof(iv));
 182
 183         sg_init_one(&sg[0], &tmpbuf, sizeof(tmpbuf));
 184         sg_init_one(&sg[1], &tmpbuf, sizeof(tmpbuf));
 185
 186         skcipher_request_set_tfm(req, call->conn->cipher);
 187         skcipher_request_set_callback(req, 0, NULL, NULL);
 188         skcipher_request_set_crypt(req, &sg[1], &sg[0], sizeof(tmpbuf), iv.x);
 189
 190         crypto_skcipher_encrypt(req);
 191         skcipher_request_zero(req);
 192
 193         memcpy(sechdr, &tmpbuf, sizeof(tmpbuf));
 194
 195         _leave(" = 0");
 196         return 0;
 197 }
 198
 199 /*
 200  * wholly encrypt a packet (level 2 security)
 201  */
 202 static int rxkad_secure_packet_encrypt(const struct rxrpc_call *call,
 203                                         struct sk_buff *skb,
 204                                         u32 data_size,
 205                                         void *sechdr)
 206 {
 207         const struct rxrpc_key_token *token;
 208         struct rxkad_level2_hdr rxkhdr
 209                 __attribute__((aligned(8))); /* must be all on one page */
 210         struct rxrpc_skb_priv *sp;
 211         SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
 212         struct rxrpc_crypt iv;
 213         struct scatterlist sg[16];
 214         struct sk_buff *trailer;
 215         unsigned int len;
 216         u16 check;
 217         int nsg;
 218         int err;
 219
 220         sp = rxrpc_skb(skb);
 221
 222         _enter("");
 223
 224         check = ntohl(sp->hdr.seq ^ sp->hdr.callNumber);
 225
 226         rxkhdr.data_size = htonl(data_size | (u32) check << 16);
 227         rxkhdr.checksum = 0;
 228
 229         /* encrypt from the session key */
 230         token = call->conn->key->payload.data[0];
 231         memcpy(&iv, token->kad->session_key, sizeof(iv));
 232
 233         sg_init_one(&sg[0], sechdr, sizeof(rxkhdr));
 234         sg_init_one(&sg[1], &rxkhdr, sizeof(rxkhdr));
 235
 236         skcipher_request_set_tfm(req, call->conn->cipher);
 237         skcipher_request_set_callback(req, 0, NULL, NULL);
 238         skcipher_request_set_crypt(req, &sg[1], &sg[0], sizeof(rxkhdr), iv.x);
 239
 240         crypto_skcipher_encrypt(req);
 241
 242         /* we want to encrypt the skbuff in-place */
 243         nsg = skb_cow_data(skb, 0, &trailer);
 244         err = -ENOMEM;
 245         if (nsg < 0 || nsg > 16)
 246                 goto out;
 247
 248         len = data_size + call->conn->size_align - 1;
 249         len &= ~(call->conn->size_align - 1);
 250
 251         sg_init_table(sg, nsg);
 252         skb_to_sgvec(skb, sg, 0, len);
 253
 254         skcipher_request_set_crypt(req, sg, sg, len, iv.x);
 255
 256         crypto_skcipher_encrypt(req);
 257
 258         _leave(" = 0");
 259         err = 0;
 260
 261 out:
 262         skcipher_request_zero(req);
 263         return err;
 264 }
 265
 266 /*
 267  * checksum an RxRPC packet header
 268  */
 269 static int rxkad_secure_packet(const struct rxrpc_call *call,
 270                                 struct sk_buff *skb,
 271                                 size_t data_size,
 272                                 void *sechdr)
 273 {
 274         struct rxrpc_skb_priv *sp;
 275         SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
 276         struct rxrpc_crypt iv;
 277         struct scatterlist sg[2];
 278         struct {
 279                 __be32 x[2];
 280         } tmpbuf __attribute__((aligned(8))); /* must all be in same page */
 281         __be32 x;
 282         u32 y;
 283         int ret;
 284
 285         sp = rxrpc_skb(skb);
 286
 287         _enter("{%d{%x}},{#%u},%zu,",
 288                call->debug_id, key_serial(call->conn->key), ntohl(sp->hdr.seq),
 289                data_size);
 290
 291         if (!call->conn->cipher)
 292                 return 0;
 293
 294         ret = key_validate(call->conn->key);
 295         if (ret < 0)
 296                 return ret;
 297
 298         /* continue encrypting from where we left off */
 299         memcpy(&iv, call->conn->csum_iv.x, sizeof(iv));
 300
 301         /* calculate the security checksum */
 302         x = htonl(call->channel << (32 - RXRPC_CIDSHIFT));
 303         x |= sp->hdr.seq & cpu_to_be32(0x3fffffff);
 304         tmpbuf.x[0] = sp->hdr.callNumber;
 305         tmpbuf.x[1] = x;
 306
 307         sg_init_one(&sg[0], &tmpbuf, sizeof(tmpbuf));
 308         sg_init_one(&sg[1], &tmpbuf, sizeof(tmpbuf));
 309
 310         skcipher_request_set_tfm(req, call->conn->cipher);
 311         skcipher_request_set_callback(req, 0, NULL, NULL);
 312         skcipher_request_set_crypt(req, &sg[1], &sg[0], sizeof(tmpbuf), iv.x);
 313
 314         crypto_skcipher_encrypt(req);
 315         skcipher_request_zero(req);
 316
 317         y = ntohl(tmpbuf.x[1]);
 318         y = (y >> 16) & 0xffff;
 319         if (y == 0)
 320                 y = 1; /* zero checksums are not permitted */
 321         sp->hdr.cksum = htons(y);
 322
 323         switch (call->conn->security_level) {
 324         case RXRPC_SECURITY_PLAIN:
 325                 ret = 0;
 326                 break;
 327         case RXRPC_SECURITY_AUTH:
 328                 ret = rxkad_secure_packet_auth(call, skb, data_size, sechdr);
 329                 break;
 330         case RXRPC_SECURITY_ENCRYPT:
 331                 ret = rxkad_secure_packet_encrypt(call, skb, data_size,
 332                                                   sechdr);
 333                 break;
 334         default:
 335                 ret = -EPERM;
 336                 break;
 337         }
 338
 339         _leave(" = %d [set %hx]", ret, y);
 340         return ret;
 341 }
 342
 343 /*
 344  * decrypt partial encryption on a packet (level 1 security)
 345  */
 346 static int rxkad_verify_packet_auth(const struct rxrpc_call *call,
 347                                     struct sk_buff *skb,
 348                                     u32 *_abort_code)
 349 {
 350         struct rxkad_level1_hdr sechdr;
 351         struct rxrpc_skb_priv *sp;
 352         SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
 353         struct rxrpc_crypt iv;
 354         struct scatterlist sg[16];
 355         struct sk_buff *trailer;
 356         u32 data_size, buf;
 357         u16 check;
 358         int nsg;
 359
 360         _enter("");
 361
 362         sp = rxrpc_skb(skb);
 363
 364         /* we want to decrypt the skbuff in-place */
 365         nsg = skb_cow_data(skb, 0, &trailer);
 366         if (nsg < 0 || nsg > 16)
 367                 goto nomem;
 368
 369         sg_init_table(sg, nsg);
 370         skb_to_sgvec(skb, sg, 0, 8);
 371
 372         /* start the decryption afresh */
 373         memset(&iv, 0, sizeof(iv));
 374
 375         skcipher_request_set_tfm(req, call->conn->cipher);
 376         skcipher_request_set_callback(req, 0, NULL, NULL);
 377         skcipher_request_set_crypt(req, sg, sg, 8, iv.x);
 378
 379         crypto_skcipher_decrypt(req);
 380         skcipher_request_zero(req);
 381
 382         /* remove the decrypted packet length */
 383         if (skb_copy_bits(skb, 0, &sechdr, sizeof(sechdr)) < 0)
 384                 goto datalen_error;
 385         if (!skb_pull(skb, sizeof(sechdr)))
 386                 BUG();
 387
 388         buf = ntohl(sechdr.data_size);
 389         data_size = buf & 0xffff;
 390
 391         check = buf >> 16;
 392         check ^= ntohl(sp->hdr.seq ^ sp->hdr.callNumber);
 393         check &= 0xffff;
 394         if (check != 0) {
 395                 *_abort_code = RXKADSEALEDINCON;
 396                 goto protocol_error;
 397         }
 398
 399         /* shorten the packet to remove the padding */
 400         if (data_size > skb->len)
 401                 goto datalen_error;
 402         else if (data_size < skb->len)
 403                 skb->len = data_size;
 404
 405         _leave(" = 0 [dlen=%x]", data_size);
 406         return 0;
 407
 408 datalen_error:
 409         *_abort_code = RXKADDATALEN;
 410 protocol_error:
 411         _leave(" = -EPROTO");
 412         return -EPROTO;
 413
 414 nomem:
 415         _leave(" = -ENOMEM");
 416         return -ENOMEM;
 417 }
 418
 419 /*
 420  * wholly decrypt a packet (level 2 security)
 421  */
 422 static int rxkad_verify_packet_encrypt(const struct rxrpc_call *call,
 423                                        struct sk_buff *skb,
 424                                        u32 *_abort_code)
 425 {
 426         const struct rxrpc_key_token *token;
 427         struct rxkad_level2_hdr sechdr;
 428         struct rxrpc_skb_priv *sp;
 429         SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
 430         struct rxrpc_crypt iv;
 431         struct scatterlist _sg[4], *sg;
 432         struct sk_buff *trailer;
 433         u32 data_size, buf;
 434         u16 check;
 435         int nsg;
 436
 437         _enter(",{%d}", skb->len);
 438
 439         sp = rxrpc_skb(skb);
 440
 441         /* we want to decrypt the skbuff in-place */
 442         nsg = skb_cow_data(skb, 0, &trailer);
 443         if (nsg < 0)
 444                 goto nomem;
 445
 446         sg = _sg;
 447         if (unlikely(nsg > 4)) {
 448                 sg = kmalloc(sizeof(*sg) * nsg, GFP_NOIO);
 449                 if (!sg)
 450                         goto nomem;
 451         }
 452
 453         sg_init_table(sg, nsg);
 454         skb_to_sgvec(skb, sg, 0, skb->len);
 455
 456         /* decrypt from the session key */
 457         token = call->conn->key->payload.data[0];
 458         memcpy(&iv, token->kad->session_key, sizeof(iv));
 459
 460         skcipher_request_set_tfm(req, call->conn->cipher);
 461         skcipher_request_set_callback(req, 0, NULL, NULL);
 462         skcipher_request_set_crypt(req, sg, sg, skb->len, iv.x);
 463
 464         crypto_skcipher_decrypt(req);
 465         skcipher_request_zero(req);
 466         if (sg != _sg)
 467                 kfree(sg);
 468
 469         /* remove the decrypted packet length */
 470         if (skb_copy_bits(skb, 0, &sechdr, sizeof(sechdr)) < 0)
 471                 goto datalen_error;
 472         if (!skb_pull(skb, sizeof(sechdr)))
 473                 BUG();
 474
 475         buf = ntohl(sechdr.data_size);
 476         data_size = buf & 0xffff;
 477
 478         check = buf >> 16;
 479         check ^= ntohl(sp->hdr.seq ^ sp->hdr.callNumber);
 480         check &= 0xffff;
 481         if (check != 0) {
 482                 *_abort_code = RXKADSEALEDINCON;
 483                 goto protocol_error;
 484         }
 485
 486         /* shorten the packet to remove the padding */
 487         if (data_size > skb->len)
 488                 goto datalen_error;
 489         else if (data_size < skb->len)
 490                 skb->len = data_size;
 491
 492         _leave(" = 0 [dlen=%x]", data_size);
 493         return 0;
 494
 495 datalen_error:
 496         *_abort_code = RXKADDATALEN;
 497 protocol_error:
 498         _leave(" = -EPROTO");
 499         return -EPROTO;
 500
 501 nomem:
 502         _leave(" = -ENOMEM");
 503         return -ENOMEM;
 504 }
 505
 506 /*
 507  * verify the security on a received packet
 508  */
 509 static int rxkad_verify_packet(const struct rxrpc_call *call,
 510                                struct sk_buff *skb,
 511                                u32 *_abort_code)
 512 {
 513         SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
 514         struct rxrpc_skb_priv *sp;
 515         struct rxrpc_crypt iv;
 516         struct scatterlist sg[2];
 517         struct {
 518                 __be32 x[2];
 519         } tmpbuf __attribute__((aligned(8))); /* must all be in same page */
 520         __be32 x;
 521         __be16 cksum;
 522         u32 y;
 523         int ret;
 524
 525         sp = rxrpc_skb(skb);
 526
 527         _enter("{%d{%x}},{#%u}",
 528                call->debug_id, key_serial(call->conn->key),
 529                ntohl(sp->hdr.seq));
 530
 531         if (!call->conn->cipher)
 532                 return 0;
 533
 534         if (sp->hdr.securityIndex != RXRPC_SECURITY_RXKAD) {
 535                 *_abort_code = RXKADINCONSISTENCY;
 536                 _leave(" = -EPROTO [not rxkad]");
 537                 return -EPROTO;
 538         }
 539
 540         /* continue encrypting from where we left off */
 541         memcpy(&iv, call->conn->csum_iv.x, sizeof(iv));
 542
 543         /* validate the security checksum */
 544         x = htonl(call->channel << (32 - RXRPC_CIDSHIFT));
 545         x |= sp->hdr.seq & cpu_to_be32(0x3fffffff);
 546         tmpbuf.x[0] = call->call_id;
 547         tmpbuf.x[1] = x;
 548
 549         sg_init_one(&sg[0], &tmpbuf, sizeof(tmpbuf));
 550         sg_init_one(&sg[1], &tmpbuf, sizeof(tmpbuf));
 551
 552         skcipher_request_set_tfm(req, call->conn->cipher);
 553         skcipher_request_set_callback(req, 0, NULL, NULL);
 554         skcipher_request_set_crypt(req, &sg[1], &sg[0], sizeof(tmpbuf), iv.x);
 555
 556         crypto_skcipher_encrypt(req);
 557         skcipher_request_zero(req);
 558
 559         y = ntohl(tmpbuf.x[1]);
 560         y = (y >> 16) & 0xffff;
 561         if (y == 0)
 562                 y = 1; /* zero checksums are not permitted */
 563
 564         cksum = htons(y);
 565         if (sp->hdr.cksum != cksum) {
 566                 *_abort_code = RXKADSEALEDINCON;
 567                 _leave(" = -EPROTO [csum failed]");
 568                 return -EPROTO;
 569         }
 570
 571         switch (call->conn->security_level) {
 572         case RXRPC_SECURITY_PLAIN:
 573                 ret = 0;
 574                 break;
 575         case RXRPC_SECURITY_AUTH:
 576                 ret = rxkad_verify_packet_auth(call, skb, _abort_code);
 577                 break;
 578         case RXRPC_SECURITY_ENCRYPT:
 579                 ret = rxkad_verify_packet_encrypt(call, skb, _abort_code);
 580                 break;
 581         default:
 582                 ret = -ENOANO;
 583                 break;
 584         }
 585
 586         _leave(" = %d", ret);
 587         return ret;
 588 }
 589
 590 /*
 591  * issue a challenge
 592  */
 593 static int rxkad_issue_challenge(struct rxrpc_connection *conn)
 594 {
 595         struct rxkad_challenge challenge;
 596         struct rxrpc_header hdr;
 597         struct msghdr msg;
 598         struct kvec iov[2];
 599         size_t len;
 600         int ret;
 601
 602         _enter("{%d,%x}", conn->debug_id, key_serial(conn->key));
 603
 604         ret = key_validate(conn->key);
 605         if (ret < 0)
 606                 return ret;
 607
 608         get_random_bytes(&conn->security_nonce, sizeof(conn->security_nonce));
 609
 610         challenge.version       = htonl(2);
 611         challenge.nonce         = htonl(conn->security_nonce);
 612         challenge.min_level     = htonl(0);
 613         challenge.__padding     = 0;
 614
 615         msg.msg_name    = &conn->trans->peer->srx.transport.sin;
 616         msg.msg_namelen = sizeof(conn->trans->peer->srx.transport.sin);
 617         msg.msg_control = NULL;
 618         msg.msg_controllen = 0;
 619         msg.msg_flags   = 0;
 620
 621         hdr.epoch       = conn->epoch;
 622         hdr.cid         = conn->cid;
 623         hdr.callNumber  = 0;
 624         hdr.seq         = 0;
 625         hdr.type        = RXRPC_PACKET_TYPE_CHALLENGE;
 626         hdr.flags       = conn->out_clientflag;
 627         hdr.userStatus  = 0;
 628         hdr.securityIndex = conn->security_ix;
 629         hdr._rsvd       = 0;
 630         hdr.serviceId   = conn->service_id;
 631
 632         iov[0].iov_base = &hdr;
 633         iov[0].iov_len  = sizeof(hdr);
 634         iov[1].iov_base = &challenge;
 635         iov[1].iov_len  = sizeof(challenge);
 636
 637         len = iov[0].iov_len + iov[1].iov_len;
 638
 639         hdr.serial = htonl(atomic_inc_return(&conn->serial));
 640         _proto("Tx CHALLENGE %%%u", ntohl(hdr.serial));
 641
 642         ret = kernel_sendmsg(conn->trans->local->socket, &msg, iov, 2, len);
 643         if (ret < 0) {
 644                 _debug("sendmsg failed: %d", ret);
 645                 return -EAGAIN;
 646         }
 647
 648         _leave(" = 0");
 649         return 0;
 650 }
 651
 652 /*
 653  * send a Kerberos security response
 654  */
 655 static int rxkad_send_response(struct rxrpc_connection *conn,
 656                                struct rxrpc_header *hdr,
 657                                struct rxkad_response *resp,
 658                                const struct rxkad_key *s2)
 659 {
 660         struct msghdr msg;
 661         struct kvec iov[3];
 662         size_t len;
 663         int ret;
 664
 665         _enter("");
 666
 667         msg.msg_name    = &conn->trans->peer->srx.transport.sin;
 668         msg.msg_namelen = sizeof(conn->trans->peer->srx.transport.sin);
 669         msg.msg_control = NULL;
 670         msg.msg_controllen = 0;
 671         msg.msg_flags   = 0;
 672
 673         hdr->epoch      = conn->epoch;
 674         hdr->seq        = 0;
 675         hdr->type       = RXRPC_PACKET_TYPE_RESPONSE;
 676         hdr->flags      = conn->out_clientflag;
 677         hdr->userStatus = 0;
 678         hdr->_rsvd      = 0;
 679
 680         iov[0].iov_base = hdr;
 681         iov[0].iov_len  = sizeof(*hdr);
 682         iov[1].iov_base = resp;
 683         iov[1].iov_len  = sizeof(*resp);
 684         iov[2].iov_base = (void *) s2->ticket;
 685         iov[2].iov_len  = s2->ticket_len;
 686
 687         len = iov[0].iov_len + iov[1].iov_len + iov[2].iov_len;
 688
 689         hdr->serial = htonl(atomic_inc_return(&conn->serial));
 690         _proto("Tx RESPONSE %%%u", ntohl(hdr->serial));
 691
 692         ret = kernel_sendmsg(conn->trans->local->socket, &msg, iov, 3, len);
 693         if (ret < 0) {
 694                 _debug("sendmsg failed: %d", ret);
 695                 return -EAGAIN;
 696         }
 697
 698         _leave(" = 0");
 699         return 0;
 700 }
 701
 702 /*
 703  * calculate the response checksum
 704  */
 705 static void rxkad_calc_response_checksum(struct rxkad_response *response)
 706 {
 707         u32 csum = 1000003;
 708         int loop;
 709         u8 *p = (u8 *) response;
 710
 711         for (loop = sizeof(*response); loop > 0; loop--)
 712                 csum = csum * 0x10204081 + *p++;
 713
 714         response->encrypted.checksum = htonl(csum);
 715 }
 716
 717 /*
 718  * load a scatterlist with a potentially split-page buffer
 719  */
 720 static void rxkad_sg_set_buf2(struct scatterlist sg[2],
 721                               void *buf, size_t buflen)
 722 {
 723         int nsg = 1;
 724
 725         sg_init_table(sg, 2);
 726
 727         sg_set_buf(&sg[0], buf, buflen);
 728         if (sg[0].offset + buflen > PAGE_SIZE) {
 729                 /* the buffer was split over two pages */
 730                 sg[0].length = PAGE_SIZE - sg[0].offset;
 731                 sg_set_buf(&sg[1], buf + sg[0].length, buflen - sg[0].length);
 732                 nsg++;
 733         }
 734
 735         sg_mark_end(&sg[nsg - 1]);
 736
 737         ASSERTCMP(sg[0].length + sg[1].length, ==, buflen);
 738 }
 739
 740 /*
 741  * encrypt the response packet
 742  */
 743 static void rxkad_encrypt_response(struct rxrpc_connection *conn,
 744                                    struct rxkad_response *resp,
 745                                    const struct rxkad_key *s2)
 746 {
 747         SKCIPHER_REQUEST_ON_STACK(req, conn->cipher);
 748         struct rxrpc_crypt iv;
 749         struct scatterlist sg[2];
 750
 751         /* continue encrypting from where we left off */
 752         memcpy(&iv, s2->session_key, sizeof(iv));
 753
 754         rxkad_sg_set_buf2(sg, &resp->encrypted, sizeof(resp->encrypted));
 755
 756         skcipher_request_set_tfm(req, conn->cipher);
 757         skcipher_request_set_callback(req, 0, NULL, NULL);
 758         skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
 759
 760         crypto_skcipher_encrypt(req);
 761         skcipher_request_zero(req);
 762 }
 763
 764 /*
 765  * respond to a challenge packet
 766  */
 767 static int rxkad_respond_to_challenge(struct rxrpc_connection *conn,
 768                                       struct sk_buff *skb,
 769                                       u32 *_abort_code)
 770 {
 771         const struct rxrpc_key_token *token;
 772         struct rxkad_challenge challenge;
 773         struct rxkad_response resp
 774                 __attribute__((aligned(8))); /* must be aligned for crypto */
 775         struct rxrpc_skb_priv *sp;
 776         u32 version, nonce, min_level, abort_code;
 777         int ret;
 778
 779         _enter("{%d,%x}", conn->debug_id, key_serial(conn->key));
 780
 781         if (!conn->key) {
 782                 _leave(" = -EPROTO [no key]");
 783                 return -EPROTO;
 784         }
 785
 786         ret = key_validate(conn->key);
 787         if (ret < 0) {
 788                 *_abort_code = RXKADEXPIRED;
 789                 return ret;
 790         }
 791
 792         abort_code = RXKADPACKETSHORT;
 793         sp = rxrpc_skb(skb);
 794         if (skb_copy_bits(skb, 0, &challenge, sizeof(challenge)) < 0)
 795                 goto protocol_error;
 796
 797         version = ntohl(challenge.version);
 798         nonce = ntohl(challenge.nonce);
 799         min_level = ntohl(challenge.min_level);
 800
 801         _proto("Rx CHALLENGE %%%u { v=%u n=%u ml=%u }",
 802                ntohl(sp->hdr.serial), version, nonce, min_level);
 803
 804         abort_code = RXKADINCONSISTENCY;
 805         if (version != RXKAD_VERSION)
 806                 goto protocol_error;
 807
 808         abort_code = RXKADLEVELFAIL;
 809         if (conn->security_level < min_level)
 810                 goto protocol_error;
 811
 812         token = conn->key->payload.data[0];
 813
 814         /* build the response packet */
 815         memset(&resp, 0, sizeof(resp));
 816
 817         resp.version = RXKAD_VERSION;
 818         resp.encrypted.epoch = conn->epoch;
 819         resp.encrypted.cid = conn->cid;
 820         resp.encrypted.securityIndex = htonl(conn->security_ix);
 821         resp.encrypted.call_id[0] =
 822                 (conn->channels[0] ? conn->channels[0]->call_id : 0);
 823         resp.encrypted.call_id[1] =
 824                 (conn->channels[1] ? conn->channels[1]->call_id : 0);
 825         resp.encrypted.call_id[2] =
 826                 (conn->channels[2] ? conn->channels[2]->call_id : 0);
 827         resp.encrypted.call_id[3] =
 828                 (conn->channels[3] ? conn->channels[3]->call_id : 0);
 829         resp.encrypted.inc_nonce = htonl(nonce + 1);
 830         resp.encrypted.level = htonl(conn->security_level);
 831         resp.kvno = htonl(token->kad->kvno);
 832         resp.ticket_len = htonl(token->kad->ticket_len);
 833
 834         /* calculate the response checksum and then do the encryption */
 835         rxkad_calc_response_checksum(&resp);
 836         rxkad_encrypt_response(conn, &resp, token->kad);
 837         return rxkad_send_response(conn, &sp->hdr, &resp, token->kad);
 838
 839 protocol_error:
 840         *_abort_code = abort_code;
 841         _leave(" = -EPROTO [%d]", abort_code);
 842         return -EPROTO;
 843 }
 844
 845 /*
 846  * decrypt the kerberos IV ticket in the response
 847  */
 848 static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
 849                                 void *ticket, size_t ticket_len,
 850                                 struct rxrpc_crypt *_session_key,
 851                                 time_t *_expiry,
 852                                 u32 *_abort_code)
 853 {
 854         struct skcipher_request *req;
 855         struct rxrpc_crypt iv, key;
 856         struct scatterlist sg[1];
 857         struct in_addr addr;
 858         unsigned int life;
 859         time_t issue, now;
 860         bool little_endian;
 861         int ret;
 862         u8 *p, *q, *name, *end;
 863
 864         _enter("{%d},{%x}", conn->debug_id, key_serial(conn->server_key));
 865
 866         *_expiry = 0;
 867
 868         ret = key_validate(conn->server_key);
 869         if (ret < 0) {
 870                 switch (ret) {
 871                 case -EKEYEXPIRED:
 872                         *_abort_code = RXKADEXPIRED;
 873                         goto error;
 874                 default:
 875                         *_abort_code = RXKADNOAUTH;
 876                         goto error;
 877                 }
 878         }
 879
 880         ASSERT(conn->server_key->payload.data[0] != NULL);
 881         ASSERTCMP((unsigned long) ticket & 7UL, ==, 0);
 882
 883         memcpy(&iv, &conn->server_key->payload.data[2], sizeof(iv));
 884
 885         req = skcipher_request_alloc(conn->server_key->payload.data[0],
 886                                      GFP_NOFS);
 887         if (!req) {
 888                 *_abort_code = RXKADNOAUTH;
 889                 ret = -ENOMEM;
 890                 goto error;
 891         }
 892
 893         sg_init_one(&sg[0], ticket, ticket_len);
 894
 895         skcipher_request_set_callback(req, 0, NULL, NULL);
 896         skcipher_request_set_crypt(req, sg, sg, ticket_len, iv.x);
 897
 898         crypto_skcipher_decrypt(req);
 899         skcipher_request_free(req);
 900
 901         p = ticket;
 902         end = p + ticket_len;
 903
 904 #define Z(size)                                         \
 905         ({                                              \
 906                 u8 *__str = p;                          \
 907                 q = memchr(p, 0, end - p);              \
 908                 if (!q || q - p > (size))               \
 909                         goto bad_ticket;                \
 910                 for (; p < q; p++)                      \
 911                         if (!isprint(*p))               \
 912                                 goto bad_ticket;        \
 913                 p++;                                    \
 914                 __str;                                  \
 915         })
 916
 917         /* extract the ticket flags */
 918         _debug("KIV FLAGS: %x", *p);
 919         little_endian = *p & 1;
 920         p++;
 921
 922         /* extract the authentication name */
 923         name = Z(ANAME_SZ);
 924         _debug("KIV ANAME: %s", name);
 925
 926         /* extract the principal's instance */
 927         name = Z(INST_SZ);
 928         _debug("KIV INST : %s", name);
 929
 930         /* extract the principal's authentication domain */
 931         name = Z(REALM_SZ);
 932         _debug("KIV REALM: %s", name);
 933
 934         if (end - p < 4 + 8 + 4 + 2)
 935                 goto bad_ticket;
 936
 937         /* get the IPv4 address of the entity that requested the ticket */
 938         memcpy(&addr, p, sizeof(addr));
 939         p += 4;
 940         _debug("KIV ADDR : %pI4", &addr);
 941
 942         /* get the session key from the ticket */
 943         memcpy(&key, p, sizeof(key));
 944         p += 8;
 945         _debug("KIV KEY  : %08x %08x", ntohl(key.n[0]), ntohl(key.n[1]));
 946         memcpy(_session_key, &key, sizeof(key));
 947
 948         /* get the ticket's lifetime */
 949         life = *p++ * 5 * 60;
 950         _debug("KIV LIFE : %u", life);
 951
 952         /* get the issue time of the ticket */
 953         if (little_endian) {
 954                 __le32 stamp;
 955                 memcpy(&stamp, p, 4);
 956                 issue = le32_to_cpu(stamp);
 957         } else {
 958                 __be32 stamp;
 959                 memcpy(&stamp, p, 4);
 960                 issue = be32_to_cpu(stamp);
 961         }
 962         p += 4;
 963         now = get_seconds();
 964         _debug("KIV ISSUE: %lx [%lx]", issue, now);
 965
 966         /* check the ticket is in date */
 967         if (issue > now) {
 968                 *_abort_code = RXKADNOAUTH;
 969                 ret = -EKEYREJECTED;
 970                 goto error;
 971         }
 972
 973         if (issue < now - life) {
 974                 *_abort_code = RXKADEXPIRED;
 975                 ret = -EKEYEXPIRED;
 976                 goto error;
 977         }
 978
 979         *_expiry = issue + life;
 980
 981         /* get the service name */
 982         name = Z(SNAME_SZ);
 983         _debug("KIV SNAME: %s", name);
 984
 985         /* get the service instance name */
 986         name = Z(INST_SZ);
 987         _debug("KIV SINST: %s", name);
 988
 989         ret = 0;
 990 error:
 991         _leave(" = %d", ret);
 992         return ret;
 993
 994 bad_ticket:
 995         *_abort_code = RXKADBADTICKET;
 996         ret = -EBADMSG;
 997         goto error;
 998 }
 999
1000 /*
1001  * decrypt the response packet
1002  */
1003 static void rxkad_decrypt_response(struct rxrpc_connection *conn,
1004                                    struct rxkad_response *resp,
1005                                    const struct rxrpc_crypt *session_key)
1006 {
1007         SKCIPHER_REQUEST_ON_STACK(req, rxkad_ci);
1008         struct scatterlist sg[2];
1009         struct rxrpc_crypt iv;
1010
1011         _enter(",,%08x%08x",
1012                ntohl(session_key->n[0]), ntohl(session_key->n[1]));
1013
1014         ASSERT(rxkad_ci != NULL);
1015
1016         mutex_lock(&rxkad_ci_mutex);
1017         if (crypto_skcipher_setkey(rxkad_ci, session_key->x,
1018                                    sizeof(*session_key)) < 0)
1019                 BUG();
1020
1021         memcpy(&iv, session_key, sizeof(iv));
1022
1023         rxkad_sg_set_buf2(sg, &resp->encrypted, sizeof(resp->encrypted));
1024
1025         skcipher_request_set_tfm(req, rxkad_ci);
1026         skcipher_request_set_callback(req, 0, NULL, NULL);
1027         skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
1028
1029         crypto_skcipher_decrypt(req);
1030         skcipher_request_zero(req);
1031
1032         mutex_unlock(&rxkad_ci_mutex);
1033
1034         _leave("");
1035 }
1036
1037 /*
1038  * verify a response
1039  */
1040 static int rxkad_verify_response(struct rxrpc_connection *conn,
1041                                  struct sk_buff *skb,
1042                                  u32 *_abort_code)
1043 {
1044         struct rxkad_response response
1045                 __attribute__((aligned(8))); /* must be aligned for crypto */
1046         struct rxrpc_skb_priv *sp;
1047         struct rxrpc_crypt session_key;
1048         time_t expiry;
1049         void *ticket;
1050         u32 abort_code, version, kvno, ticket_len, level;
1051         __be32 csum;
1052         int ret;
1053
1054         _enter("{%d,%x}", conn->debug_id, key_serial(conn->server_key));
1055
1056         abort_code = RXKADPACKETSHORT;
1057         if (skb_copy_bits(skb, 0, &response, sizeof(response)) < 0)
1058                 goto protocol_error;
1059         if (!pskb_pull(skb, sizeof(response)))
1060                 BUG();
1061
1062         version = ntohl(response.version);
1063         ticket_len = ntohl(response.ticket_len);
1064         kvno = ntohl(response.kvno);
1065         sp = rxrpc_skb(skb);
1066         _proto("Rx RESPONSE %%%u { v=%u kv=%u tl=%u }",
1067                ntohl(sp->hdr.serial), version, kvno, ticket_len);
1068
1069         abort_code = RXKADINCONSISTENCY;
1070         if (version != RXKAD_VERSION)
1071                 goto protocol_error;
1072
1073         abort_code = RXKADTICKETLEN;
1074         if (ticket_len < 4 || ticket_len > MAXKRB5TICKETLEN)
1075                 goto protocol_error;
1076
1077         abort_code = RXKADUNKNOWNKEY;
1078         if (kvno >= RXKAD_TKT_TYPE_KERBEROS_V5)
1079                 goto protocol_error;
1080
1081         /* extract the kerberos ticket and decrypt and decode it */
1082         ticket = kmalloc(ticket_len, GFP_NOFS);
1083         if (!ticket)
1084                 return -ENOMEM;
1085
1086         abort_code = RXKADPACKETSHORT;
1087         if (skb_copy_bits(skb, 0, ticket, ticket_len) < 0)
1088                 goto protocol_error_free;
1089
1090         ret = rxkad_decrypt_ticket(conn, ticket, ticket_len, &session_key,
1091                                    &expiry, &abort_code);
1092         if (ret < 0) {
1093                 *_abort_code = abort_code;
1094                 kfree(ticket);
1095                 return ret;
1096         }
1097
1098         /* use the session key from inside the ticket to decrypt the
1099          * response */
1100         rxkad_decrypt_response(conn, &response, &session_key);
1101
1102         abort_code = RXKADSEALEDINCON;
1103         if (response.encrypted.epoch != conn->epoch)
1104                 goto protocol_error_free;
1105         if (response.encrypted.cid != conn->cid)
1106                 goto protocol_error_free;
1107         if (ntohl(response.encrypted.securityIndex) != conn->security_ix)
1108                 goto protocol_error_free;
1109         csum = response.encrypted.checksum;
1110         response.encrypted.checksum = 0;
1111         rxkad_calc_response_checksum(&response);
1112         if (response.encrypted.checksum != csum)
1113                 goto protocol_error_free;
1114
1115         if (ntohl(response.encrypted.call_id[0]) > INT_MAX ||
1116             ntohl(response.encrypted.call_id[1]) > INT_MAX ||
1117             ntohl(response.encrypted.call_id[2]) > INT_MAX ||
1118             ntohl(response.encrypted.call_id[3]) > INT_MAX)
1119                 goto protocol_error_free;
1120
1121         abort_code = RXKADOUTOFSEQUENCE;
1122         if (response.encrypted.inc_nonce != htonl(conn->security_nonce + 1))
1123                 goto protocol_error_free;
1124
1125         abort_code = RXKADLEVELFAIL;
1126         level = ntohl(response.encrypted.level);
1127         if (level > RXRPC_SECURITY_ENCRYPT)
1128                 goto protocol_error_free;
1129         conn->security_level = level;
1130
1131         /* create a key to hold the security data and expiration time - after
1132          * this the connection security can be handled in exactly the same way
1133          * as for a client connection */
1134         ret = rxrpc_get_server_data_key(conn, &session_key, expiry, kvno);
1135         if (ret < 0) {
1136                 kfree(ticket);
1137                 return ret;
1138         }
1139
1140         kfree(ticket);
1141         _leave(" = 0");
1142         return 0;
1143
1144 protocol_error_free:
1145         kfree(ticket);
1146 protocol_error:
1147         *_abort_code = abort_code;
1148         _leave(" = -EPROTO [%d]", abort_code);
1149         return -EPROTO;
1150 }
1151
1152 /*
1153  * clear the connection security
1154  */
1155 static void rxkad_clear(struct rxrpc_connection *conn)
1156 {
1157         _enter("");
1158
1159         if (conn->cipher)
1160                 crypto_free_skcipher(conn->cipher);
1161 }
1162
1163 /*
1164  * RxRPC Kerberos-based security
1165  */
1166 static struct rxrpc_security rxkad = {
1167         .owner                          = THIS_MODULE,
1168         .name                           = "rxkad",
1169         .security_index                 = RXRPC_SECURITY_RXKAD,
1170         .init_connection_security       = rxkad_init_connection_security,
1171         .prime_packet_security          = rxkad_prime_packet_security,
1172         .secure_packet                  = rxkad_secure_packet,
1173         .verify_packet                  = rxkad_verify_packet,
1174         .issue_challenge                = rxkad_issue_challenge,
1175         .respond_to_challenge           = rxkad_respond_to_challenge,
1176         .verify_response                = rxkad_verify_response,
1177         .clear                          = rxkad_clear,
1178 };
1179
1180 static __init int rxkad_init(void)
1181 {
1182         _enter("");
1183
1184         /* pin the cipher we need so that the crypto layer doesn't invoke
1185          * keventd to go get it */
1186         rxkad_ci = crypto_alloc_skcipher("pcbc(fcrypt)", 0, CRYPTO_ALG_ASYNC);
1187         if (IS_ERR(rxkad_ci))
1188                 return PTR_ERR(rxkad_ci);
1189
1190         return rxrpc_register_security(&rxkad);
1191 }
1192
1193 module_init(rxkad_init);
1194
1195 static __exit void rxkad_exit(void)
1196 {
1197         _enter("");
1198
1199         rxrpc_unregister_security(&rxkad);
1200         crypto_free_skcipher(rxkad_ci);
1201 }
1202
1203 module_exit(rxkad_exit);