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