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                 break;
  84         case RXRPC_SECURITY_ENCRYPT:
  85                 conn->size_align = 8;
  86                 conn->security_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 int 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;
 109         struct rxrpc_crypt iv;
 110         __be32 *tmpbuf;
 111         size_t tmpsize = 4 * sizeof(__be32);
 112
 113         _enter("");
 114
 115         if (!conn->params.key)
 116                 return 0;
 117
 118         tmpbuf = kmalloc(tmpsize, GFP_KERNEL);
 119         if (!tmpbuf)
 120                 return -ENOMEM;
 121
 122         token = conn->params.key->payload.data[0];
 123         memcpy(&iv, token->kad->session_key, sizeof(iv));
 124
 125         tmpbuf[0] = htonl(conn->proto.epoch);
 126         tmpbuf[1] = htonl(conn->proto.cid);
 127         tmpbuf[2] = 0;
 128         tmpbuf[3] = htonl(conn->security_ix);
 129
 130         sg_init_one(&sg, tmpbuf, tmpsize);
 131         skcipher_request_set_tfm(req, conn->cipher);
 132         skcipher_request_set_callback(req, 0, NULL, NULL);
 133         skcipher_request_set_crypt(req, &sg, &sg, tmpsize, iv.x);
 134         crypto_skcipher_encrypt(req);
 135         skcipher_request_zero(req);
 136
 137         memcpy(&conn->csum_iv, tmpbuf + 2, sizeof(conn->csum_iv));
 138         kfree(tmpbuf);
 139         _leave(" = 0");
 140         return 0;
 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 = rxrpc_skb(skb);
 152         SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
 153         struct rxkad_level1_hdr hdr;
 154         struct rxrpc_crypt iv;
 155         struct scatterlist sg;
 156         u16 check;
 157
 158         _enter("");
 159
 160         check = sp->hdr.seq ^ call->call_id;
 161         data_size |= (u32)check << 16;
 162
 163         hdr.data_size = htonl(data_size);
 164         memcpy(sechdr, &hdr, sizeof(hdr));
 165
 166         /* start the encryption afresh */
 167         memset(&iv, 0, sizeof(iv));
 168
 169         sg_init_one(&sg, sechdr, 8);
 170         skcipher_request_set_tfm(req, call->conn->cipher);
 171         skcipher_request_set_callback(req, 0, NULL, NULL);
 172         skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
 173         crypto_skcipher_encrypt(req);
 174         skcipher_request_zero(req);
 175
 176         _leave(" = 0");
 177         return 0;
 178 }
 179
 180 /*
 181  * wholly encrypt a packet (level 2 security)
 182  */
 183 static int rxkad_secure_packet_encrypt(const struct rxrpc_call *call,
 184                                        struct sk_buff *skb,
 185                                        u32 data_size,
 186                                        void *sechdr)
 187 {
 188         const struct rxrpc_key_token *token;
 189         struct rxkad_level2_hdr rxkhdr;
 190         struct rxrpc_skb_priv *sp;
 191         SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
 192         struct rxrpc_crypt iv;
 193         struct scatterlist sg[16];
 194         struct sk_buff *trailer;
 195         unsigned int len;
 196         u16 check;
 197         int nsg;
 198         int err;
 199
 200         sp = rxrpc_skb(skb);
 201
 202         _enter("");
 203
 204         check = sp->hdr.seq ^ call->call_id;
 205
 206         rxkhdr.data_size = htonl(data_size | (u32)check << 16);
 207         rxkhdr.checksum = 0;
 208         memcpy(sechdr, &rxkhdr, sizeof(rxkhdr));
 209
 210         /* encrypt from the session key */
 211         token = call->conn->params.key->payload.data[0];
 212         memcpy(&iv, token->kad->session_key, sizeof(iv));
 213
 214         sg_init_one(&sg[0], sechdr, sizeof(rxkhdr));
 215         skcipher_request_set_tfm(req, call->conn->cipher);
 216         skcipher_request_set_callback(req, 0, NULL, NULL);
 217         skcipher_request_set_crypt(req, &sg[0], &sg[0], sizeof(rxkhdr), iv.x);
 218         crypto_skcipher_encrypt(req);
 219
 220         /* we want to encrypt the skbuff in-place */
 221         nsg = skb_cow_data(skb, 0, &trailer);
 222         err = -ENOMEM;
 223         if (nsg < 0 || nsg > 16)
 224                 goto out;
 225
 226         len = data_size + call->conn->size_align - 1;
 227         len &= ~(call->conn->size_align - 1);
 228
 229         sg_init_table(sg, nsg);
 230         err = skb_to_sgvec(skb, sg, 0, len);
 231         if (unlikely(err < 0))
 232                 goto out;
 233         skcipher_request_set_crypt(req, sg, sg, len, iv.x);
 234         crypto_skcipher_encrypt(req);
 235
 236         _leave(" = 0");
 237         err = 0;
 238
 239 out:
 240         skcipher_request_zero(req);
 241         return err;
 242 }
 243
 244 /*
 245  * checksum an RxRPC packet header
 246  */
 247 static int rxkad_secure_packet(struct rxrpc_call *call,
 248                                struct sk_buff *skb,
 249                                size_t data_size,
 250                                void *sechdr)
 251 {
 252         struct rxrpc_skb_priv *sp;
 253         SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
 254         struct rxrpc_crypt iv;
 255         struct scatterlist sg;
 256         u32 x, y;
 257         int ret;
 258
 259         sp = rxrpc_skb(skb);
 260
 261         _enter("{%d{%x}},{#%u},%zu,",
 262                call->debug_id, key_serial(call->conn->params.key),
 263                sp->hdr.seq, data_size);
 264
 265         if (!call->conn->cipher)
 266                 return 0;
 267
 268         ret = key_validate(call->conn->params.key);
 269         if (ret < 0)
 270                 return ret;
 271
 272         /* continue encrypting from where we left off */
 273         memcpy(&iv, call->conn->csum_iv.x, sizeof(iv));
 274
 275         /* calculate the security checksum */
 276         x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT);
 277         x |= sp->hdr.seq & 0x3fffffff;
 278         call->crypto_buf[0] = htonl(call->call_id);
 279         call->crypto_buf[1] = htonl(x);
 280
 281         sg_init_one(&sg, call->crypto_buf, 8);
 282         skcipher_request_set_tfm(req, call->conn->cipher);
 283         skcipher_request_set_callback(req, 0, NULL, NULL);
 284         skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
 285         crypto_skcipher_encrypt(req);
 286         skcipher_request_zero(req);
 287
 288         y = ntohl(call->crypto_buf[1]);
 289         y = (y >> 16) & 0xffff;
 290         if (y == 0)
 291                 y = 1; /* zero checksums are not permitted */
 292         sp->hdr.cksum = y;
 293
 294         switch (call->conn->params.security_level) {
 295         case RXRPC_SECURITY_PLAIN:
 296                 ret = 0;
 297                 break;
 298         case RXRPC_SECURITY_AUTH:
 299                 ret = rxkad_secure_packet_auth(call, skb, data_size, sechdr);
 300                 break;
 301         case RXRPC_SECURITY_ENCRYPT:
 302                 ret = rxkad_secure_packet_encrypt(call, skb, data_size,
 303                                                   sechdr);
 304                 break;
 305         default:
 306                 ret = -EPERM;
 307                 break;
 308         }
 309
 310         _leave(" = %d [set %hx]", ret, y);
 311         return ret;
 312 }
 313
 314 /*
 315  * decrypt partial encryption on a packet (level 1 security)
 316  */
 317 static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb,
 318                                  unsigned int offset, unsigned int len,
 319                                  rxrpc_seq_t seq)
 320 {
 321         struct rxkad_level1_hdr sechdr;
 322         SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
 323         struct rxrpc_crypt iv;
 324         struct scatterlist sg[16];
 325         struct sk_buff *trailer;
 326         bool aborted;
 327         u32 data_size, buf;
 328         u16 check;
 329         int nsg, ret;
 330
 331         _enter("");
 332
 333         if (len < 8) {
 334                 aborted = rxrpc_abort_eproto(call, skb, "rxkad_1_hdr", "V1H",
 335                                            RXKADSEALEDINCON);
 336                 goto protocol_error;
 337         }
 338
 339         /* Decrypt the skbuff in-place.  TODO: We really want to decrypt
 340          * directly into the target buffer.
 341          */
 342         nsg = skb_cow_data(skb, 0, &trailer);
 343         if (nsg < 0 || nsg > 16)
 344                 goto nomem;
 345
 346         sg_init_table(sg, nsg);
 347         ret = skb_to_sgvec(skb, sg, offset, 8);
 348         if (unlikely(ret < 0))
 349                 return ret;
 350
 351         /* start the decryption afresh */
 352         memset(&iv, 0, sizeof(iv));
 353
 354         skcipher_request_set_tfm(req, call->conn->cipher);
 355         skcipher_request_set_callback(req, 0, NULL, NULL);
 356         skcipher_request_set_crypt(req, sg, sg, 8, iv.x);
 357         crypto_skcipher_decrypt(req);
 358         skcipher_request_zero(req);
 359
 360         /* Extract the decrypted packet length */
 361         if (skb_copy_bits(skb, offset, &sechdr, sizeof(sechdr)) < 0) {
 362                 aborted = rxrpc_abort_eproto(call, skb, "rxkad_1_len", "XV1",
 363                                              RXKADDATALEN);
 364                 goto protocol_error;
 365         }
 366         offset += sizeof(sechdr);
 367         len -= sizeof(sechdr);
 368
 369         buf = ntohl(sechdr.data_size);
 370         data_size = buf & 0xffff;
 371
 372         check = buf >> 16;
 373         check ^= seq ^ call->call_id;
 374         check &= 0xffff;
 375         if (check != 0) {
 376                 aborted = rxrpc_abort_eproto(call, skb, "rxkad_1_check", "V1C",
 377                                              RXKADSEALEDINCON);
 378                 goto protocol_error;
 379         }
 380
 381         if (data_size > len) {
 382                 aborted = rxrpc_abort_eproto(call, skb, "rxkad_1_datalen", "V1L",
 383                                              RXKADDATALEN);
 384                 goto protocol_error;
 385         }
 386
 387         _leave(" = 0 [dlen=%x]", data_size);
 388         return 0;
 389
 390 protocol_error:
 391         if (aborted)
 392                 rxrpc_send_abort_packet(call);
 393         return -EPROTO;
 394
 395 nomem:
 396         _leave(" = -ENOMEM");
 397         return -ENOMEM;
 398 }
 399
 400 /*
 401  * wholly decrypt a packet (level 2 security)
 402  */
 403 static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb,
 404                                  unsigned int offset, unsigned int len,
 405                                  rxrpc_seq_t seq)
 406 {
 407         const struct rxrpc_key_token *token;
 408         struct rxkad_level2_hdr sechdr;
 409         SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
 410         struct rxrpc_crypt iv;
 411         struct scatterlist _sg[4], *sg;
 412         struct sk_buff *trailer;
 413         bool aborted;
 414         u32 data_size, buf;
 415         u16 check;
 416         int nsg, ret;
 417
 418         _enter(",{%d}", skb->len);
 419
 420         if (len < 8) {
 421                 aborted = rxrpc_abort_eproto(call, skb, "rxkad_2_hdr", "V2H",
 422                                              RXKADSEALEDINCON);
 423                 goto protocol_error;
 424         }
 425
 426         /* Decrypt the skbuff in-place.  TODO: We really want to decrypt
 427          * directly into the target buffer.
 428          */
 429         nsg = skb_cow_data(skb, 0, &trailer);
 430         if (nsg < 0)
 431                 goto nomem;
 432
 433         sg = _sg;
 434         if (unlikely(nsg > 4)) {
 435                 sg = kmalloc(sizeof(*sg) * nsg, GFP_NOIO);
 436                 if (!sg)
 437                         goto nomem;
 438         }
 439
 440         sg_init_table(sg, nsg);
 441         ret = skb_to_sgvec(skb, sg, offset, len);
 442         if (unlikely(ret < 0)) {
 443                 if (sg != _sg)
 444                         kfree(sg);
 445                 return ret;
 446         }
 447
 448         /* decrypt from the session key */
 449         token = call->conn->params.key->payload.data[0];
 450         memcpy(&iv, token->kad->session_key, sizeof(iv));
 451
 452         skcipher_request_set_tfm(req, call->conn->cipher);
 453         skcipher_request_set_callback(req, 0, NULL, NULL);
 454         skcipher_request_set_crypt(req, sg, sg, len, iv.x);
 455         crypto_skcipher_decrypt(req);
 456         skcipher_request_zero(req);
 457         if (sg != _sg)
 458                 kfree(sg);
 459
 460         /* Extract the decrypted packet length */
 461         if (skb_copy_bits(skb, offset, &sechdr, sizeof(sechdr)) < 0) {
 462                 aborted = rxrpc_abort_eproto(call, skb, "rxkad_2_len", "XV2",
 463                                              RXKADDATALEN);
 464                 goto protocol_error;
 465         }
 466         offset += sizeof(sechdr);
 467         len -= sizeof(sechdr);
 468
 469         buf = ntohl(sechdr.data_size);
 470         data_size = buf & 0xffff;
 471
 472         check = buf >> 16;
 473         check ^= seq ^ call->call_id;
 474         check &= 0xffff;
 475         if (check != 0) {
 476                 aborted = rxrpc_abort_eproto(call, skb, "rxkad_2_check", "V2C",
 477                                              RXKADSEALEDINCON);
 478                 goto protocol_error;
 479         }
 480
 481         if (data_size > len) {
 482                 aborted = rxrpc_abort_eproto(call, skb, "rxkad_2_datalen", "V2L",
 483                                              RXKADDATALEN);
 484                 goto protocol_error;
 485         }
 486
 487         _leave(" = 0 [dlen=%x]", data_size);
 488         return 0;
 489
 490 protocol_error:
 491         if (aborted)
 492                 rxrpc_send_abort_packet(call);
 493         return -EPROTO;
 494
 495 nomem:
 496         _leave(" = -ENOMEM");
 497         return -ENOMEM;
 498 }
 499
 500 /*
 501  * Verify the security on a received packet or subpacket (if part of a
 502  * jumbo packet).
 503  */
 504 static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb,
 505                                unsigned int offset, unsigned int len,
 506                                rxrpc_seq_t seq, u16 expected_cksum)
 507 {
 508         SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
 509         struct rxrpc_crypt iv;
 510         struct scatterlist sg;
 511         bool aborted;
 512         u16 cksum;
 513         u32 x, y;
 514
 515         _enter("{%d{%x}},{#%u}",
 516                call->debug_id, key_serial(call->conn->params.key), seq);
 517
 518         if (!call->conn->cipher)
 519                 return 0;
 520
 521         /* continue encrypting from where we left off */
 522         memcpy(&iv, call->conn->csum_iv.x, sizeof(iv));
 523
 524         /* validate the security checksum */
 525         x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT);
 526         x |= seq & 0x3fffffff;
 527         call->crypto_buf[0] = htonl(call->call_id);
 528         call->crypto_buf[1] = htonl(x);
 529
 530         sg_init_one(&sg, call->crypto_buf, 8);
 531         skcipher_request_set_tfm(req, call->conn->cipher);
 532         skcipher_request_set_callback(req, 0, NULL, NULL);
 533         skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
 534         crypto_skcipher_encrypt(req);
 535         skcipher_request_zero(req);
 536
 537         y = ntohl(call->crypto_buf[1]);
 538         cksum = (y >> 16) & 0xffff;
 539         if (cksum == 0)
 540                 cksum = 1; /* zero checksums are not permitted */
 541
 542         if (cksum != expected_cksum) {
 543                 aborted = rxrpc_abort_eproto(call, skb, "rxkad_csum", "VCK",
 544                                              RXKADSEALEDINCON);
 545                 goto protocol_error;
 546         }
 547
 548         switch (call->conn->params.security_level) {
 549         case RXRPC_SECURITY_PLAIN:
 550                 return 0;
 551         case RXRPC_SECURITY_AUTH:
 552                 return rxkad_verify_packet_1(call, skb, offset, len, seq);
 553         case RXRPC_SECURITY_ENCRYPT:
 554                 return rxkad_verify_packet_2(call, skb, offset, len, seq);
 555         default:
 556                 return -ENOANO;
 557         }
 558
 559 protocol_error:
 560         if (aborted)
 561                 rxrpc_send_abort_packet(call);
 562         return -EPROTO;
 563 }
 564
 565 /*
 566  * Locate the data contained in a packet that was partially encrypted.
 567  */
 568 static void rxkad_locate_data_1(struct rxrpc_call *call, struct sk_buff *skb,
 569                                 unsigned int *_offset, unsigned int *_len)
 570 {
 571         struct rxkad_level1_hdr sechdr;
 572
 573         if (skb_copy_bits(skb, *_offset, &sechdr, sizeof(sechdr)) < 0)
 574                 BUG();
 575         *_offset += sizeof(sechdr);
 576         *_len = ntohl(sechdr.data_size) & 0xffff;
 577 }
 578
 579 /*
 580  * Locate the data contained in a packet that was completely encrypted.
 581  */
 582 static void rxkad_locate_data_2(struct rxrpc_call *call, struct sk_buff *skb,
 583                                 unsigned int *_offset, unsigned int *_len)
 584 {
 585         struct rxkad_level2_hdr sechdr;
 586
 587         if (skb_copy_bits(skb, *_offset, &sechdr, sizeof(sechdr)) < 0)
 588                 BUG();
 589         *_offset += sizeof(sechdr);
 590         *_len = ntohl(sechdr.data_size) & 0xffff;
 591 }
 592
 593 /*
 594  * Locate the data contained in an already decrypted packet.
 595  */
 596 static void rxkad_locate_data(struct rxrpc_call *call, struct sk_buff *skb,
 597                               unsigned int *_offset, unsigned int *_len)
 598 {
 599         switch (call->conn->params.security_level) {
 600         case RXRPC_SECURITY_AUTH:
 601                 rxkad_locate_data_1(call, skb, _offset, _len);
 602                 return;
 603         case RXRPC_SECURITY_ENCRYPT:
 604                 rxkad_locate_data_2(call, skb, _offset, _len);
 605                 return;
 606         default:
 607                 return;
 608         }
 609 }
 610
 611 /*
 612  * issue a challenge
 613  */
 614 static int rxkad_issue_challenge(struct rxrpc_connection *conn)
 615 {
 616         struct rxkad_challenge challenge;
 617         struct rxrpc_wire_header whdr;
 618         struct msghdr msg;
 619         struct kvec iov[2];
 620         size_t len;
 621         u32 serial;
 622         int ret;
 623
 624         _enter("{%d,%x}", conn->debug_id, key_serial(conn->params.key));
 625
 626         ret = key_validate(conn->params.key);
 627         if (ret < 0)
 628                 return ret;
 629
 630         get_random_bytes(&conn->security_nonce, sizeof(conn->security_nonce));
 631
 632         challenge.version       = htonl(2);
 633         challenge.nonce         = htonl(conn->security_nonce);
 634         challenge.min_level     = htonl(0);
 635         challenge.__padding     = 0;
 636
 637         msg.msg_name    = &conn->params.peer->srx.transport;
 638         msg.msg_namelen = conn->params.peer->srx.transport_len;
 639         msg.msg_control = NULL;
 640         msg.msg_controllen = 0;
 641         msg.msg_flags   = 0;
 642
 643         whdr.epoch      = htonl(conn->proto.epoch);
 644         whdr.cid        = htonl(conn->proto.cid);
 645         whdr.callNumber = 0;
 646         whdr.seq        = 0;
 647         whdr.type       = RXRPC_PACKET_TYPE_CHALLENGE;
 648         whdr.flags      = conn->out_clientflag;
 649         whdr.userStatus = 0;
 650         whdr.securityIndex = conn->security_ix;
 651         whdr._rsvd      = 0;
 652         whdr.serviceId  = htons(conn->service_id);
 653
 654         iov[0].iov_base = &whdr;
 655         iov[0].iov_len  = sizeof(whdr);
 656         iov[1].iov_base = &challenge;
 657         iov[1].iov_len  = sizeof(challenge);
 658
 659         len = iov[0].iov_len + iov[1].iov_len;
 660
 661         serial = atomic_inc_return(&conn->serial);
 662         whdr.serial = htonl(serial);
 663         _proto("Tx CHALLENGE %%%u", serial);
 664
 665         ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 2, len);
 666         if (ret < 0) {
 667                 _debug("sendmsg failed: %d", ret);
 668                 return -EAGAIN;
 669         }
 670
 671         _leave(" = 0");
 672         return 0;
 673 }
 674
 675 /*
 676  * send a Kerberos security response
 677  */
 678 static int rxkad_send_response(struct rxrpc_connection *conn,
 679                                struct rxrpc_host_header *hdr,
 680                                struct rxkad_response *resp,
 681                                const struct rxkad_key *s2)
 682 {
 683         struct rxrpc_wire_header whdr;
 684         struct msghdr msg;
 685         struct kvec iov[3];
 686         size_t len;
 687         u32 serial;
 688         int ret;
 689
 690         _enter("");
 691
 692         msg.msg_name    = &conn->params.peer->srx.transport;
 693         msg.msg_namelen = conn->params.peer->srx.transport_len;
 694         msg.msg_control = NULL;
 695         msg.msg_controllen = 0;
 696         msg.msg_flags   = 0;
 697
 698         memset(&whdr, 0, sizeof(whdr));
 699         whdr.epoch      = htonl(hdr->epoch);
 700         whdr.cid        = htonl(hdr->cid);
 701         whdr.type       = RXRPC_PACKET_TYPE_RESPONSE;
 702         whdr.flags      = conn->out_clientflag;
 703         whdr.securityIndex = hdr->securityIndex;
 704         whdr.serviceId  = htons(hdr->serviceId);
 705
 706         iov[0].iov_base = &whdr;
 707         iov[0].iov_len  = sizeof(whdr);
 708         iov[1].iov_base = resp;
 709         iov[1].iov_len  = sizeof(*resp);
 710         iov[2].iov_base = (void *)s2->ticket;
 711         iov[2].iov_len  = s2->ticket_len;
 712
 713         len = iov[0].iov_len + iov[1].iov_len + iov[2].iov_len;
 714
 715         serial = atomic_inc_return(&conn->serial);
 716         whdr.serial = htonl(serial);
 717         _proto("Tx RESPONSE %%%u", serial);
 718
 719         ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 3, len);
 720         if (ret < 0) {
 721                 _debug("sendmsg failed: %d", ret);
 722                 return -EAGAIN;
 723         }
 724
 725         _leave(" = 0");
 726         return 0;
 727 }
 728
 729 /*
 730  * calculate the response checksum
 731  */
 732 static void rxkad_calc_response_checksum(struct rxkad_response *response)
 733 {
 734         u32 csum = 1000003;
 735         int loop;
 736         u8 *p = (u8 *) response;
 737
 738         for (loop = sizeof(*response); loop > 0; loop--)
 739                 csum = csum * 0x10204081 + *p++;
 740
 741         response->encrypted.checksum = htonl(csum);
 742 }
 743
 744 /*
 745  * encrypt the response packet
 746  */
 747 static void rxkad_encrypt_response(struct rxrpc_connection *conn,
 748                                    struct rxkad_response *resp,
 749                                    const struct rxkad_key *s2)
 750 {
 751         SKCIPHER_REQUEST_ON_STACK(req, conn->cipher);
 752         struct rxrpc_crypt iv;
 753         struct scatterlist sg[1];
 754
 755         /* continue encrypting from where we left off */
 756         memcpy(&iv, s2->session_key, sizeof(iv));
 757
 758         sg_init_table(sg, 1);
 759         sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted));
 760         skcipher_request_set_tfm(req, conn->cipher);
 761         skcipher_request_set_callback(req, 0, NULL, NULL);
 762         skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
 763         crypto_skcipher_encrypt(req);
 764         skcipher_request_zero(req);
 765 }
 766
 767 /*
 768  * respond to a challenge packet
 769  */
 770 static int rxkad_respond_to_challenge(struct rxrpc_connection *conn,
 771                                       struct sk_buff *skb,
 772                                       u32 *_abort_code)
 773 {
 774         const struct rxrpc_key_token *token;
 775         struct rxkad_challenge challenge;
 776         struct rxkad_response resp
 777                 __attribute__((aligned(8))); /* must be aligned for crypto */
 778         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 779         const char *eproto;
 780         u32 version, nonce, min_level, abort_code;
 781         int ret;
 782
 783         _enter("{%d,%x}", conn->debug_id, key_serial(conn->params.key));
 784
 785         eproto = tracepoint_string("chall_no_key");
 786         abort_code = RX_PROTOCOL_ERROR;
 787         if (!conn->params.key)
 788                 goto protocol_error;
 789
 790         abort_code = RXKADEXPIRED;
 791         ret = key_validate(conn->params.key);
 792         if (ret < 0)
 793                 goto other_error;
 794
 795         eproto = tracepoint_string("chall_short");
 796         abort_code = RXKADPACKETSHORT;
 797         if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
 798                           &challenge, sizeof(challenge)) < 0)
 799                 goto protocol_error;
 800
 801         version = ntohl(challenge.version);
 802         nonce = ntohl(challenge.nonce);
 803         min_level = ntohl(challenge.min_level);
 804
 805         _proto("Rx CHALLENGE %%%u { v=%u n=%u ml=%u }",
 806                sp->hdr.serial, version, nonce, min_level);
 807
 808         eproto = tracepoint_string("chall_ver");
 809         abort_code = RXKADINCONSISTENCY;
 810         if (version != RXKAD_VERSION)
 811                 goto protocol_error;
 812
 813         abort_code = RXKADLEVELFAIL;
 814         ret = -EACCES;
 815         if (conn->params.security_level < min_level)
 816                 goto other_error;
 817
 818         token = conn->params.key->payload.data[0];
 819
 820         /* build the response packet */
 821         memset(&resp, 0, sizeof(resp));
 822
 823         resp.version                    = htonl(RXKAD_VERSION);
 824         resp.encrypted.epoch            = htonl(conn->proto.epoch);
 825         resp.encrypted.cid              = htonl(conn->proto.cid);
 826         resp.encrypted.securityIndex    = htonl(conn->security_ix);
 827         resp.encrypted.inc_nonce        = htonl(nonce + 1);
 828         resp.encrypted.level            = htonl(conn->params.security_level);
 829         resp.kvno                       = htonl(token->kad->kvno);
 830         resp.ticket_len                 = htonl(token->kad->ticket_len);
 831
 832         resp.encrypted.call_id[0] = htonl(conn->channels[0].call_counter);
 833         resp.encrypted.call_id[1] = htonl(conn->channels[1].call_counter);
 834         resp.encrypted.call_id[2] = htonl(conn->channels[2].call_counter);
 835         resp.encrypted.call_id[3] = htonl(conn->channels[3].call_counter);
 836
 837         /* calculate the response checksum and then do the encryption */
 838         rxkad_calc_response_checksum(&resp);
 839         rxkad_encrypt_response(conn, &resp, token->kad);
 840         return rxkad_send_response(conn, &sp->hdr, &resp, token->kad);
 841
 842 protocol_error:
 843         trace_rxrpc_rx_eproto(NULL, sp->hdr.serial, eproto);
 844         ret = -EPROTO;
 845 other_error:
 846         *_abort_code = abort_code;
 847         return ret;
 848 }
 849
 850 /*
 851  * decrypt the kerberos IV ticket in the response
 852  */
 853 static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
 854                                 struct sk_buff *skb,
 855                                 void *ticket, size_t ticket_len,
 856                                 struct rxrpc_crypt *_session_key,
 857                                 time64_t *_expiry,
 858                                 u32 *_abort_code)
 859 {
 860         struct skcipher_request *req;
 861         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 862         struct rxrpc_crypt iv, key;
 863         struct scatterlist sg[1];
 864         struct in_addr addr;
 865         unsigned int life;
 866         const char *eproto;
 867         time64_t issue, now;
 868         bool little_endian;
 869         int ret;
 870         u32 abort_code;
 871         u8 *p, *q, *name, *end;
 872
 873         _enter("{%d},{%x}", conn->debug_id, key_serial(conn->server_key));
 874
 875         *_expiry = 0;
 876
 877         ret = key_validate(conn->server_key);
 878         if (ret < 0) {
 879                 switch (ret) {
 880                 case -EKEYEXPIRED:
 881                         abort_code = RXKADEXPIRED;
 882                         goto other_error;
 883                 default:
 884                         abort_code = RXKADNOAUTH;
 885                         goto other_error;
 886                 }
 887         }
 888
 889         ASSERT(conn->server_key->payload.data[0] != NULL);
 890         ASSERTCMP((unsigned long) ticket & 7UL, ==, 0);
 891
 892         memcpy(&iv, &conn->server_key->payload.data[2], sizeof(iv));
 893
 894         ret = -ENOMEM;
 895         req = skcipher_request_alloc(conn->server_key->payload.data[0],
 896                                      GFP_NOFS);
 897         if (!req)
 898                 goto temporary_error;
 899
 900         sg_init_one(&sg[0], ticket, ticket_len);
 901         skcipher_request_set_callback(req, 0, NULL, NULL);
 902         skcipher_request_set_crypt(req, sg, sg, ticket_len, iv.x);
 903         crypto_skcipher_decrypt(req);
 904         skcipher_request_free(req);
 905
 906         p = ticket;
 907         end = p + ticket_len;
 908
 909 #define Z(field)                                        \
 910         ({                                              \
 911                 u8 *__str = p;                          \
 912                 eproto = tracepoint_string("rxkad_bad_"#field); \
 913                 q = memchr(p, 0, end - p);              \
 914                 if (!q || q - p > (field##_SZ))         \
 915                         goto bad_ticket;                \
 916                 for (; p < q; p++)                      \
 917                         if (!isprint(*p))               \
 918                                 goto bad_ticket;        \
 919                 p++;                                    \
 920                 __str;                                  \
 921         })
 922
 923         /* extract the ticket flags */
 924         _debug("KIV FLAGS: %x", *p);
 925         little_endian = *p & 1;
 926         p++;
 927
 928         /* extract the authentication name */
 929         name = Z(ANAME);
 930         _debug("KIV ANAME: %s", name);
 931
 932         /* extract the principal's instance */
 933         name = Z(INST);
 934         _debug("KIV INST : %s", name);
 935
 936         /* extract the principal's authentication domain */
 937         name = Z(REALM);
 938         _debug("KIV REALM: %s", name);
 939
 940         eproto = tracepoint_string("rxkad_bad_len");
 941         if (end - p < 4 + 8 + 4 + 2)
 942                 goto bad_ticket;
 943
 944         /* get the IPv4 address of the entity that requested the ticket */
 945         memcpy(&addr, p, sizeof(addr));
 946         p += 4;
 947         _debug("KIV ADDR : %pI4", &addr);
 948
 949         /* get the session key from the ticket */
 950         memcpy(&key, p, sizeof(key));
 951         p += 8;
 952         _debug("KIV KEY  : %08x %08x", ntohl(key.n[0]), ntohl(key.n[1]));
 953         memcpy(_session_key, &key, sizeof(key));
 954
 955         /* get the ticket's lifetime */
 956         life = *p++ * 5 * 60;
 957         _debug("KIV LIFE : %u", life);
 958
 959         /* get the issue time of the ticket */
 960         if (little_endian) {
 961                 __le32 stamp;
 962                 memcpy(&stamp, p, 4);
 963                 issue = rxrpc_u32_to_time64(le32_to_cpu(stamp));
 964         } else {
 965                 __be32 stamp;
 966                 memcpy(&stamp, p, 4);
 967                 issue = rxrpc_u32_to_time64(be32_to_cpu(stamp));
 968         }
 969         p += 4;
 970         now = ktime_get_real_seconds();
 971         _debug("KIV ISSUE: %llx [%llx]", issue, now);
 972
 973         /* check the ticket is in date */
 974         if (issue > now) {
 975                 abort_code = RXKADNOAUTH;
 976                 ret = -EKEYREJECTED;
 977                 goto other_error;
 978         }
 979
 980         if (issue < now - life) {
 981                 abort_code = RXKADEXPIRED;
 982                 ret = -EKEYEXPIRED;
 983                 goto other_error;
 984         }
 985
 986         *_expiry = issue + life;
 987
 988         /* get the service name */
 989         name = Z(SNAME);
 990         _debug("KIV SNAME: %s", name);
 991
 992         /* get the service instance name */
 993         name = Z(INST);
 994         _debug("KIV SINST: %s", name);
 995         return 0;
 996
 997 bad_ticket:
 998         trace_rxrpc_rx_eproto(NULL, sp->hdr.serial, eproto);
 999         abort_code = RXKADBADTICKET;
1000         ret = -EPROTO;
1001 other_error:
1002         *_abort_code = abort_code;
1003         return ret;
1004 temporary_error:
1005         return ret;
1006 }
1007
1008 /*
1009  * decrypt the response packet
1010  */
1011 static void rxkad_decrypt_response(struct rxrpc_connection *conn,
1012                                    struct rxkad_response *resp,
1013                                    const struct rxrpc_crypt *session_key)
1014 {
1015         SKCIPHER_REQUEST_ON_STACK(req, rxkad_ci);
1016         struct scatterlist sg[1];
1017         struct rxrpc_crypt iv;
1018
1019         _enter(",,%08x%08x",
1020                ntohl(session_key->n[0]), ntohl(session_key->n[1]));
1021
1022         ASSERT(rxkad_ci != NULL);
1023
1024         mutex_lock(&rxkad_ci_mutex);
1025         if (crypto_skcipher_setkey(rxkad_ci, session_key->x,
1026                                    sizeof(*session_key)) < 0)
1027                 BUG();
1028
1029         memcpy(&iv, session_key, sizeof(iv));
1030
1031         sg_init_table(sg, 1);
1032         sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted));
1033         skcipher_request_set_tfm(req, rxkad_ci);
1034         skcipher_request_set_callback(req, 0, NULL, NULL);
1035         skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
1036         crypto_skcipher_decrypt(req);
1037         skcipher_request_zero(req);
1038
1039         mutex_unlock(&rxkad_ci_mutex);
1040
1041         _leave("");
1042 }
1043
1044 /*
1045  * verify a response
1046  */
1047 static int rxkad_verify_response(struct rxrpc_connection *conn,
1048                                  struct sk_buff *skb,
1049                                  u32 *_abort_code)
1050 {
1051         struct rxkad_response response
1052                 __attribute__((aligned(8))); /* must be aligned for crypto */
1053         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1054         struct rxrpc_crypt session_key;
1055         const char *eproto;
1056         time64_t expiry;
1057         void *ticket;
1058         u32 abort_code, version, kvno, ticket_len, level;
1059         __be32 csum;
1060         int ret, i;
1061
1062         _enter("{%d,%x}", conn->debug_id, key_serial(conn->server_key));
1063
1064         eproto = tracepoint_string("rxkad_rsp_short");
1065         abort_code = RXKADPACKETSHORT;
1066         if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
1067                           &response, sizeof(response)) < 0)
1068                 goto protocol_error;
1069         if (!pskb_pull(skb, sizeof(response)))
1070                 BUG();
1071
1072         version = ntohl(response.version);
1073         ticket_len = ntohl(response.ticket_len);
1074         kvno = ntohl(response.kvno);
1075         _proto("Rx RESPONSE %%%u { v=%u kv=%u tl=%u }",
1076                sp->hdr.serial, version, kvno, ticket_len);
1077
1078         eproto = tracepoint_string("rxkad_rsp_ver");
1079         abort_code = RXKADINCONSISTENCY;
1080         if (version != RXKAD_VERSION)
1081                 goto protocol_error;
1082
1083         eproto = tracepoint_string("rxkad_rsp_tktlen");
1084         abort_code = RXKADTICKETLEN;
1085         if (ticket_len < 4 || ticket_len > MAXKRB5TICKETLEN)
1086                 goto protocol_error;
1087
1088         eproto = tracepoint_string("rxkad_rsp_unkkey");
1089         abort_code = RXKADUNKNOWNKEY;
1090         if (kvno >= RXKAD_TKT_TYPE_KERBEROS_V5)
1091                 goto protocol_error;
1092
1093         /* extract the kerberos ticket and decrypt and decode it */
1094         ret = -ENOMEM;
1095         ticket = kmalloc(ticket_len, GFP_NOFS);
1096         if (!ticket)
1097                 goto temporary_error;
1098
1099         eproto = tracepoint_string("rxkad_tkt_short");
1100         abort_code = RXKADPACKETSHORT;
1101         if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
1102                           ticket, ticket_len) < 0)
1103                 goto protocol_error_free;
1104
1105         ret = rxkad_decrypt_ticket(conn, skb, ticket, ticket_len, &session_key,
1106                                    &expiry, _abort_code);
1107         if (ret < 0)
1108                 goto temporary_error_free;
1109
1110         /* use the session key from inside the ticket to decrypt the
1111          * response */
1112         rxkad_decrypt_response(conn, &response, &session_key);
1113
1114         eproto = tracepoint_string("rxkad_rsp_param");
1115         abort_code = RXKADSEALEDINCON;
1116         if (ntohl(response.encrypted.epoch) != conn->proto.epoch)
1117                 goto protocol_error_free;
1118         if (ntohl(response.encrypted.cid) != conn->proto.cid)
1119                 goto protocol_error_free;
1120         if (ntohl(response.encrypted.securityIndex) != conn->security_ix)
1121                 goto protocol_error_free;
1122         csum = response.encrypted.checksum;
1123         response.encrypted.checksum = 0;
1124         rxkad_calc_response_checksum(&response);
1125         eproto = tracepoint_string("rxkad_rsp_csum");
1126         if (response.encrypted.checksum != csum)
1127                 goto protocol_error_free;
1128
1129         spin_lock(&conn->channel_lock);
1130         for (i = 0; i < RXRPC_MAXCALLS; i++) {
1131                 struct rxrpc_call *call;
1132                 u32 call_id = ntohl(response.encrypted.call_id[i]);
1133
1134                 eproto = tracepoint_string("rxkad_rsp_callid");
1135                 if (call_id > INT_MAX)
1136                         goto protocol_error_unlock;
1137
1138                 eproto = tracepoint_string("rxkad_rsp_callctr");
1139                 if (call_id < conn->channels[i].call_counter)
1140                         goto protocol_error_unlock;
1141
1142                 eproto = tracepoint_string("rxkad_rsp_callst");
1143                 if (call_id > conn->channels[i].call_counter) {
1144                         call = rcu_dereference_protected(
1145                                 conn->channels[i].call,
1146                                 lockdep_is_held(&conn->channel_lock));
1147                         if (call && call->state < RXRPC_CALL_COMPLETE)
1148                                 goto protocol_error_unlock;
1149                         conn->channels[i].call_counter = call_id;
1150                 }
1151         }
1152         spin_unlock(&conn->channel_lock);
1153
1154         eproto = tracepoint_string("rxkad_rsp_seq");
1155         abort_code = RXKADOUTOFSEQUENCE;
1156         if (ntohl(response.encrypted.inc_nonce) != conn->security_nonce + 1)
1157                 goto protocol_error_free;
1158
1159         eproto = tracepoint_string("rxkad_rsp_level");
1160         abort_code = RXKADLEVELFAIL;
1161         level = ntohl(response.encrypted.level);
1162         if (level > RXRPC_SECURITY_ENCRYPT)
1163                 goto protocol_error_free;
1164         conn->params.security_level = level;
1165
1166         /* create a key to hold the security data and expiration time - after
1167          * this the connection security can be handled in exactly the same way
1168          * as for a client connection */
1169         ret = rxrpc_get_server_data_key(conn, &session_key, expiry, kvno);
1170         if (ret < 0)
1171                 goto temporary_error_free;
1172
1173         kfree(ticket);
1174         _leave(" = 0");
1175         return 0;
1176
1177 protocol_error_unlock:
1178         spin_unlock(&conn->channel_lock);
1179 protocol_error_free:
1180         kfree(ticket);
1181 protocol_error:
1182         trace_rxrpc_rx_eproto(NULL, sp->hdr.serial, eproto);
1183         *_abort_code = abort_code;
1184         return -EPROTO;
1185
1186 temporary_error_free:
1187         kfree(ticket);
1188 temporary_error:
1189         /* Ignore the response packet if we got a temporary error such as
1190          * ENOMEM.  We just want to send the challenge again.  Note that we
1191          * also come out this way if the ticket decryption fails.
1192          */
1193         return ret;
1194 }
1195
1196 /*
1197  * clear the connection security
1198  */
1199 static void rxkad_clear(struct rxrpc_connection *conn)
1200 {
1201         _enter("");
1202
1203         if (conn->cipher)
1204                 crypto_free_skcipher(conn->cipher);
1205 }
1206
1207 /*
1208  * Initialise the rxkad security service.
1209  */
1210 static int rxkad_init(void)
1211 {
1212         /* pin the cipher we need so that the crypto layer doesn't invoke
1213          * keventd to go get it */
1214         rxkad_ci = crypto_alloc_skcipher("pcbc(fcrypt)", 0, CRYPTO_ALG_ASYNC);
1215         return PTR_ERR_OR_ZERO(rxkad_ci);
1216 }
1217
1218 /*
1219  * Clean up the rxkad security service.
1220  */
1221 static void rxkad_exit(void)
1222 {
1223         if (rxkad_ci)
1224                 crypto_free_skcipher(rxkad_ci);
1225 }
1226
1227 /*
1228  * RxRPC Kerberos-based security
1229  */
1230 const struct rxrpc_security rxkad = {
1231         .name                           = "rxkad",
1232         .security_index                 = RXRPC_SECURITY_RXKAD,
1233         .init                           = rxkad_init,
1234         .exit                           = rxkad_exit,
1235         .init_connection_security       = rxkad_init_connection_security,
1236         .prime_packet_security          = rxkad_prime_packet_security,
1237         .secure_packet                  = rxkad_secure_packet,
1238         .verify_packet                  = rxkad_verify_packet,
1239         .locate_data                    = rxkad_locate_data,
1240         .issue_challenge                = rxkad_issue_challenge,
1241         .respond_to_challenge           = rxkad_respond_to_challenge,
1242         .verify_response                = rxkad_verify_response,
1243         .clear                          = rxkad_clear,
1244 };