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