gss_krb5_wrap.c revision fffdaef2eb4a7333952e55cf97f1fc0fcc35f981
1/* 2 * COPYRIGHT (c) 2008 3 * The Regents of the University of Michigan 4 * ALL RIGHTS RESERVED 5 * 6 * Permission is granted to use, copy, create derivative works 7 * and redistribute this software and such derivative works 8 * for any purpose, so long as the name of The University of 9 * Michigan is not used in any advertising or publicity 10 * pertaining to the use of distribution of this software 11 * without specific, written prior authorization. If the 12 * above copyright notice or any other identification of the 13 * University of Michigan is included in any copy of any 14 * portion of this software, then the disclaimer below must 15 * also be included. 16 * 17 * THIS SOFTWARE IS PROVIDED AS IS, WITHOUT REPRESENTATION 18 * FROM THE UNIVERSITY OF MICHIGAN AS TO ITS FITNESS FOR ANY 19 * PURPOSE, AND WITHOUT WARRANTY BY THE UNIVERSITY OF 20 * MICHIGAN OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING 21 * WITHOUT LIMITATION THE IMPLIED WARRANTIES OF 22 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE 23 * REGENTS OF THE UNIVERSITY OF MICHIGAN SHALL NOT BE LIABLE 24 * FOR ANY DAMAGES, INCLUDING SPECIAL, INDIRECT, INCIDENTAL, OR 25 * CONSEQUENTIAL DAMAGES, WITH RESPECT TO ANY CLAIM ARISING 26 * OUT OF OR IN CONNECTION WITH THE USE OF THE SOFTWARE, EVEN 27 * IF IT HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGES. 29 */ 30 31#include <linux/types.h> 32#include <linux/jiffies.h> 33#include <linux/sunrpc/gss_krb5.h> 34#include <linux/random.h> 35#include <linux/pagemap.h> 36#include <linux/crypto.h> 37 38#ifdef RPC_DEBUG 39# define RPCDBG_FACILITY RPCDBG_AUTH 40#endif 41 42static inline int 43gss_krb5_padding(int blocksize, int length) 44{ 45 return blocksize - (length % blocksize); 46} 47 48static inline void 49gss_krb5_add_padding(struct xdr_buf *buf, int offset, int blocksize) 50{ 51 int padding = gss_krb5_padding(blocksize, buf->len - offset); 52 char *p; 53 struct kvec *iov; 54 55 if (buf->page_len || buf->tail[0].iov_len) 56 iov = &buf->tail[0]; 57 else 58 iov = &buf->head[0]; 59 p = iov->iov_base + iov->iov_len; 60 iov->iov_len += padding; 61 buf->len += padding; 62 memset(p, padding, padding); 63} 64 65static inline int 66gss_krb5_remove_padding(struct xdr_buf *buf, int blocksize) 67{ 68 u8 *ptr; 69 u8 pad; 70 size_t len = buf->len; 71 72 if (len <= buf->head[0].iov_len) { 73 pad = *(u8 *)(buf->head[0].iov_base + len - 1); 74 if (pad > buf->head[0].iov_len) 75 return -EINVAL; 76 buf->head[0].iov_len -= pad; 77 goto out; 78 } else 79 len -= buf->head[0].iov_len; 80 if (len <= buf->page_len) { 81 unsigned int last = (buf->page_base + len - 1) 82 >>PAGE_CACHE_SHIFT; 83 unsigned int offset = (buf->page_base + len - 1) 84 & (PAGE_CACHE_SIZE - 1); 85 ptr = kmap_atomic(buf->pages[last], KM_USER0); 86 pad = *(ptr + offset); 87 kunmap_atomic(ptr, KM_USER0); 88 goto out; 89 } else 90 len -= buf->page_len; 91 BUG_ON(len > buf->tail[0].iov_len); 92 pad = *(u8 *)(buf->tail[0].iov_base + len - 1); 93out: 94 /* XXX: NOTE: we do not adjust the page lengths--they represent 95 * a range of data in the real filesystem page cache, and we need 96 * to know that range so the xdr code can properly place read data. 97 * However adjusting the head length, as we do above, is harmless. 98 * In the case of a request that fits into a single page, the server 99 * also uses length and head length together to determine the original 100 * start of the request to copy the request for deferal; so it's 101 * easier on the server if we adjust head and tail length in tandem. 102 * It's not really a problem that we don't fool with the page and 103 * tail lengths, though--at worst badly formed xdr might lead the 104 * server to attempt to parse the padding. 105 * XXX: Document all these weird requirements for gss mechanism 106 * wrap/unwrap functions. */ 107 if (pad > blocksize) 108 return -EINVAL; 109 if (buf->len > pad) 110 buf->len -= pad; 111 else 112 return -EINVAL; 113 return 0; 114} 115 116void 117gss_krb5_make_confounder(char *p, u32 conflen) 118{ 119 static u64 i = 0; 120 u64 *q = (u64 *)p; 121 122 /* rfc1964 claims this should be "random". But all that's really 123 * necessary is that it be unique. And not even that is necessary in 124 * our case since our "gssapi" implementation exists only to support 125 * rpcsec_gss, so we know that the only buffers we will ever encrypt 126 * already begin with a unique sequence number. Just to hedge my bets 127 * I'll make a half-hearted attempt at something unique, but ensuring 128 * uniqueness would mean worrying about atomicity and rollover, and I 129 * don't care enough. */ 130 131 /* initialize to random value */ 132 if (i == 0) { 133 i = random32(); 134 i = (i << 32) | random32(); 135 } 136 137 switch (conflen) { 138 case 16: 139 *q++ = i++; 140 /* fall through */ 141 case 8: 142 *q++ = i++; 143 break; 144 default: 145 BUG(); 146 } 147} 148 149/* Assumptions: the head and tail of inbuf are ours to play with. 150 * The pages, however, may be real pages in the page cache and we replace 151 * them with scratch pages from **pages before writing to them. */ 152/* XXX: obviously the above should be documentation of wrap interface, 153 * and shouldn't be in this kerberos-specific file. */ 154 155/* XXX factor out common code with seal/unseal. */ 156 157static u32 158gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset, 159 struct xdr_buf *buf, struct page **pages) 160{ 161 char cksumdata[GSS_KRB5_MAX_CKSUM_LEN]; 162 struct xdr_netobj md5cksum = {.len = sizeof(cksumdata), 163 .data = cksumdata}; 164 int blocksize = 0, plainlen; 165 unsigned char *ptr, *msg_start; 166 s32 now; 167 int headlen; 168 struct page **tmp_pages; 169 u32 seq_send; 170 u8 *cksumkey; 171 u32 conflen = kctx->gk5e->conflen; 172 173 dprintk("RPC: %s\n", __func__); 174 175 now = get_seconds(); 176 177 blocksize = crypto_blkcipher_blocksize(kctx->enc); 178 gss_krb5_add_padding(buf, offset, blocksize); 179 BUG_ON((buf->len - offset) % blocksize); 180 plainlen = conflen + buf->len - offset; 181 182 headlen = g_token_size(&kctx->mech_used, 183 GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength + plainlen) - 184 (buf->len - offset); 185 186 ptr = buf->head[0].iov_base + offset; 187 /* shift data to make room for header. */ 188 xdr_extend_head(buf, offset, headlen); 189 190 /* XXX Would be cleverer to encrypt while copying. */ 191 BUG_ON((buf->len - offset - headlen) % blocksize); 192 193 g_make_token_header(&kctx->mech_used, 194 GSS_KRB5_TOK_HDR_LEN + 195 kctx->gk5e->cksumlength + plainlen, &ptr); 196 197 198 /* ptr now at header described in rfc 1964, section 1.2.1: */ 199 ptr[0] = (unsigned char) ((KG_TOK_WRAP_MSG >> 8) & 0xff); 200 ptr[1] = (unsigned char) (KG_TOK_WRAP_MSG & 0xff); 201 202 msg_start = ptr + GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength; 203 204 *(__be16 *)(ptr + 2) = cpu_to_le16(kctx->gk5e->signalg); 205 memset(ptr + 4, 0xff, 4); 206 *(__be16 *)(ptr + 4) = cpu_to_le16(kctx->gk5e->sealalg); 207 208 gss_krb5_make_confounder(msg_start, conflen); 209 210 if (kctx->gk5e->keyed_cksum) 211 cksumkey = kctx->cksum; 212 else 213 cksumkey = NULL; 214 215 /* XXXJBF: UGH!: */ 216 tmp_pages = buf->pages; 217 buf->pages = pages; 218 if (make_checksum(kctx, ptr, 8, buf, offset + headlen - conflen, 219 cksumkey, KG_USAGE_SEAL, &md5cksum)) 220 return GSS_S_FAILURE; 221 buf->pages = tmp_pages; 222 223 memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len); 224 225 spin_lock(&krb5_seq_lock); 226 seq_send = kctx->seq_send++; 227 spin_unlock(&krb5_seq_lock); 228 229 /* XXX would probably be more efficient to compute checksum 230 * and encrypt at the same time: */ 231 if ((krb5_make_seq_num(kctx, kctx->seq, kctx->initiate ? 0 : 0xff, 232 seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8))) 233 return GSS_S_FAILURE; 234 235 if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC) { 236 struct crypto_blkcipher *cipher; 237 int err; 238 cipher = crypto_alloc_blkcipher(kctx->gk5e->encrypt_name, 0, 239 CRYPTO_ALG_ASYNC); 240 if (IS_ERR(cipher)) 241 return GSS_S_FAILURE; 242 243 krb5_rc4_setup_enc_key(kctx, cipher, seq_send); 244 245 err = gss_encrypt_xdr_buf(cipher, buf, 246 offset + headlen - conflen, pages); 247 crypto_free_blkcipher(cipher); 248 if (err) 249 return GSS_S_FAILURE; 250 } else { 251 if (gss_encrypt_xdr_buf(kctx->enc, buf, 252 offset + headlen - conflen, pages)) 253 return GSS_S_FAILURE; 254 } 255 256 return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE; 257} 258 259static u32 260gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf) 261{ 262 int signalg; 263 int sealalg; 264 char cksumdata[GSS_KRB5_MAX_CKSUM_LEN]; 265 struct xdr_netobj md5cksum = {.len = sizeof(cksumdata), 266 .data = cksumdata}; 267 s32 now; 268 int direction; 269 s32 seqnum; 270 unsigned char *ptr; 271 int bodysize; 272 void *data_start, *orig_start; 273 int data_len; 274 int blocksize; 275 u32 conflen = kctx->gk5e->conflen; 276 int crypt_offset; 277 u8 *cksumkey; 278 279 dprintk("RPC: gss_unwrap_kerberos\n"); 280 281 ptr = (u8 *)buf->head[0].iov_base + offset; 282 if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr, 283 buf->len - offset)) 284 return GSS_S_DEFECTIVE_TOKEN; 285 286 if ((ptr[0] != ((KG_TOK_WRAP_MSG >> 8) & 0xff)) || 287 (ptr[1] != (KG_TOK_WRAP_MSG & 0xff))) 288 return GSS_S_DEFECTIVE_TOKEN; 289 290 /* XXX sanity-check bodysize?? */ 291 292 /* get the sign and seal algorithms */ 293 294 signalg = ptr[2] + (ptr[3] << 8); 295 if (signalg != kctx->gk5e->signalg) 296 return GSS_S_DEFECTIVE_TOKEN; 297 298 sealalg = ptr[4] + (ptr[5] << 8); 299 if (sealalg != kctx->gk5e->sealalg) 300 return GSS_S_DEFECTIVE_TOKEN; 301 302 if ((ptr[6] != 0xff) || (ptr[7] != 0xff)) 303 return GSS_S_DEFECTIVE_TOKEN; 304 305 /* 306 * Data starts after token header and checksum. ptr points 307 * to the beginning of the token header 308 */ 309 crypt_offset = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) - 310 (unsigned char *)buf->head[0].iov_base; 311 312 /* 313 * Need plaintext seqnum to derive encryption key for arcfour-hmac 314 */ 315 if (krb5_get_seq_num(kctx, ptr + GSS_KRB5_TOK_HDR_LEN, 316 ptr + 8, &direction, &seqnum)) 317 return GSS_S_BAD_SIG; 318 319 if ((kctx->initiate && direction != 0xff) || 320 (!kctx->initiate && direction != 0)) 321 return GSS_S_BAD_SIG; 322 323 if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC) { 324 struct crypto_blkcipher *cipher; 325 int err; 326 327 cipher = crypto_alloc_blkcipher(kctx->gk5e->encrypt_name, 0, 328 CRYPTO_ALG_ASYNC); 329 if (IS_ERR(cipher)) 330 return GSS_S_FAILURE; 331 332 krb5_rc4_setup_enc_key(kctx, cipher, seqnum); 333 334 err = gss_decrypt_xdr_buf(cipher, buf, crypt_offset); 335 crypto_free_blkcipher(cipher); 336 if (err) 337 return GSS_S_DEFECTIVE_TOKEN; 338 } else { 339 if (gss_decrypt_xdr_buf(kctx->enc, buf, crypt_offset)) 340 return GSS_S_DEFECTIVE_TOKEN; 341 } 342 343 if (kctx->gk5e->keyed_cksum) 344 cksumkey = kctx->cksum; 345 else 346 cksumkey = NULL; 347 348 if (make_checksum(kctx, ptr, 8, buf, crypt_offset, 349 cksumkey, KG_USAGE_SEAL, &md5cksum)) 350 return GSS_S_FAILURE; 351 352 if (memcmp(md5cksum.data, ptr + GSS_KRB5_TOK_HDR_LEN, 353 kctx->gk5e->cksumlength)) 354 return GSS_S_BAD_SIG; 355 356 /* it got through unscathed. Make sure the context is unexpired */ 357 358 now = get_seconds(); 359 360 if (now > kctx->endtime) 361 return GSS_S_CONTEXT_EXPIRED; 362 363 /* do sequencing checks */ 364 365 /* Copy the data back to the right position. XXX: Would probably be 366 * better to copy and encrypt at the same time. */ 367 368 blocksize = crypto_blkcipher_blocksize(kctx->enc); 369 data_start = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) + 370 conflen; 371 orig_start = buf->head[0].iov_base + offset; 372 data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start; 373 memmove(orig_start, data_start, data_len); 374 buf->head[0].iov_len -= (data_start - orig_start); 375 buf->len -= (data_start - orig_start); 376 377 if (gss_krb5_remove_padding(buf, blocksize)) 378 return GSS_S_DEFECTIVE_TOKEN; 379 380 return GSS_S_COMPLETE; 381} 382 383/* 384 * We cannot currently handle tokens with rotated data. We need a 385 * generalized routine to rotate the data in place. It is anticipated 386 * that we won't encounter rotated data in the general case. 387 */ 388static u32 389rotate_left(struct krb5_ctx *kctx, u32 offset, struct xdr_buf *buf, u16 rrc) 390{ 391 unsigned int realrrc = rrc % (buf->len - offset - GSS_KRB5_TOK_HDR_LEN); 392 393 if (realrrc == 0) 394 return 0; 395 396 dprintk("%s: cannot process token with rotated data: " 397 "rrc %u, realrrc %u\n", __func__, rrc, realrrc); 398 return 1; 399} 400 401static u32 402gss_wrap_kerberos_v2(struct krb5_ctx *kctx, u32 offset, 403 struct xdr_buf *buf, struct page **pages) 404{ 405 int blocksize; 406 u8 *ptr, *plainhdr; 407 s32 now; 408 u8 flags = 0x00; 409 __be16 *be16ptr, ec = 0; 410 __be64 *be64ptr; 411 u32 err; 412 413 dprintk("RPC: %s\n", __func__); 414 415 if (kctx->gk5e->encrypt_v2 == NULL) 416 return GSS_S_FAILURE; 417 418 /* make room for gss token header */ 419 if (xdr_extend_head(buf, offset, GSS_KRB5_TOK_HDR_LEN)) 420 return GSS_S_FAILURE; 421 422 /* construct gss token header */ 423 ptr = plainhdr = buf->head[0].iov_base + offset; 424 *ptr++ = (unsigned char) ((KG2_TOK_WRAP>>8) & 0xff); 425 *ptr++ = (unsigned char) (KG2_TOK_WRAP & 0xff); 426 427 if ((kctx->flags & KRB5_CTX_FLAG_INITIATOR) == 0) 428 flags |= KG2_TOKEN_FLAG_SENTBYACCEPTOR; 429 if ((kctx->flags & KRB5_CTX_FLAG_ACCEPTOR_SUBKEY) != 0) 430 flags |= KG2_TOKEN_FLAG_ACCEPTORSUBKEY; 431 /* We always do confidentiality in wrap tokens */ 432 flags |= KG2_TOKEN_FLAG_SEALED; 433 434 *ptr++ = flags; 435 *ptr++ = 0xff; 436 be16ptr = (__be16 *)ptr; 437 438 blocksize = crypto_blkcipher_blocksize(kctx->acceptor_enc); 439 *be16ptr++ = cpu_to_be16(ec); 440 /* "inner" token header always uses 0 for RRC */ 441 *be16ptr++ = cpu_to_be16(0); 442 443 be64ptr = (__be64 *)be16ptr; 444 spin_lock(&krb5_seq_lock); 445 *be64ptr = cpu_to_be64(kctx->seq_send64++); 446 spin_unlock(&krb5_seq_lock); 447 448 err = (*kctx->gk5e->encrypt_v2)(kctx, offset, buf, ec, pages); 449 if (err) 450 return err; 451 452 now = get_seconds(); 453 return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE; 454} 455 456static u32 457gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf) 458{ 459 s32 now; 460 u64 seqnum; 461 u8 *ptr; 462 u8 flags = 0x00; 463 u16 ec, rrc; 464 int err; 465 u32 headskip, tailskip; 466 u8 decrypted_hdr[GSS_KRB5_TOK_HDR_LEN]; 467 unsigned int movelen; 468 469 470 dprintk("RPC: %s\n", __func__); 471 472 if (kctx->gk5e->decrypt_v2 == NULL) 473 return GSS_S_FAILURE; 474 475 ptr = buf->head[0].iov_base + offset; 476 477 if (be16_to_cpu(*((__be16 *)ptr)) != KG2_TOK_WRAP) 478 return GSS_S_DEFECTIVE_TOKEN; 479 480 flags = ptr[2]; 481 if ((!kctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) || 482 (kctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR))) 483 return GSS_S_BAD_SIG; 484 485 if ((flags & KG2_TOKEN_FLAG_SEALED) == 0) { 486 dprintk("%s: token missing expected sealed flag\n", __func__); 487 return GSS_S_DEFECTIVE_TOKEN; 488 } 489 490 if (ptr[3] != 0xff) 491 return GSS_S_DEFECTIVE_TOKEN; 492 493 ec = be16_to_cpup((__be16 *)(ptr + 4)); 494 rrc = be16_to_cpup((__be16 *)(ptr + 6)); 495 496 seqnum = be64_to_cpup((__be64 *)(ptr + 8)); 497 498 if (rrc != 0) { 499 err = rotate_left(kctx, offset, buf, rrc); 500 if (err) 501 return GSS_S_FAILURE; 502 } 503 504 err = (*kctx->gk5e->decrypt_v2)(kctx, offset, buf, 505 &headskip, &tailskip); 506 if (err) 507 return GSS_S_FAILURE; 508 509 /* 510 * Retrieve the decrypted gss token header and verify 511 * it against the original 512 */ 513 err = read_bytes_from_xdr_buf(buf, 514 buf->len - GSS_KRB5_TOK_HDR_LEN - tailskip, 515 decrypted_hdr, GSS_KRB5_TOK_HDR_LEN); 516 if (err) { 517 dprintk("%s: error %u getting decrypted_hdr\n", __func__, err); 518 return GSS_S_FAILURE; 519 } 520 if (memcmp(ptr, decrypted_hdr, 6) 521 || memcmp(ptr + 8, decrypted_hdr + 8, 8)) { 522 dprintk("%s: token hdr, plaintext hdr mismatch!\n", __func__); 523 return GSS_S_FAILURE; 524 } 525 526 /* do sequencing checks */ 527 528 /* it got through unscathed. Make sure the context is unexpired */ 529 now = get_seconds(); 530 if (now > kctx->endtime) 531 return GSS_S_CONTEXT_EXPIRED; 532 533 /* 534 * Move the head data back to the right position in xdr_buf. 535 * We ignore any "ec" data since it might be in the head or 536 * the tail, and we really don't need to deal with it. 537 * Note that buf->head[0].iov_len may indicate the available 538 * head buffer space rather than that actually occupied. 539 */ 540 movelen = min_t(unsigned int, buf->head[0].iov_len, buf->len); 541 movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip; 542 BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen > 543 buf->head[0].iov_len); 544 memmove(ptr, ptr + GSS_KRB5_TOK_HDR_LEN + headskip, movelen); 545 buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip; 546 buf->len -= GSS_KRB5_TOK_HDR_LEN + headskip; 547 548 return GSS_S_COMPLETE; 549} 550 551u32 552gss_wrap_kerberos(struct gss_ctx *gctx, int offset, 553 struct xdr_buf *buf, struct page **pages) 554{ 555 struct krb5_ctx *kctx = gctx->internal_ctx_id; 556 557 switch (kctx->enctype) { 558 default: 559 BUG(); 560 case ENCTYPE_DES_CBC_RAW: 561 case ENCTYPE_DES3_CBC_RAW: 562 case ENCTYPE_ARCFOUR_HMAC: 563 return gss_wrap_kerberos_v1(kctx, offset, buf, pages); 564 case ENCTYPE_AES128_CTS_HMAC_SHA1_96: 565 case ENCTYPE_AES256_CTS_HMAC_SHA1_96: 566 return gss_wrap_kerberos_v2(kctx, offset, buf, pages); 567 } 568} 569 570u32 571gss_unwrap_kerberos(struct gss_ctx *gctx, int offset, struct xdr_buf *buf) 572{ 573 struct krb5_ctx *kctx = gctx->internal_ctx_id; 574 575 switch (kctx->enctype) { 576 default: 577 BUG(); 578 case ENCTYPE_DES_CBC_RAW: 579 case ENCTYPE_DES3_CBC_RAW: 580 case ENCTYPE_ARCFOUR_HMAC: 581 return gss_unwrap_kerberos_v1(kctx, offset, buf); 582 case ENCTYPE_AES128_CTS_HMAC_SHA1_96: 583 case ENCTYPE_AES256_CTS_HMAC_SHA1_96: 584 return gss_unwrap_kerberos_v2(kctx, offset, buf); 585 } 586} 587 588