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 if (pad > blocksize) 95 return -EINVAL; 96 if (buf->len > pad) 97 buf->len -= pad; 98 else 99 return -EINVAL; 100 return 0; 101} 102 103void 104gss_krb5_make_confounder(char *p, u32 conflen) 105{ 106 static u64 i = 0; 107 u64 *q = (u64 *)p; 108 109 /* rfc1964 claims this should be "random". But all that's really 110 * necessary is that it be unique. And not even that is necessary in 111 * our case since our "gssapi" implementation exists only to support 112 * rpcsec_gss, so we know that the only buffers we will ever encrypt 113 * already begin with a unique sequence number. Just to hedge my bets 114 * I'll make a half-hearted attempt at something unique, but ensuring 115 * uniqueness would mean worrying about atomicity and rollover, and I 116 * don't care enough. */ 117 118 /* initialize to random value */ 119 if (i == 0) { 120 i = random32(); 121 i = (i << 32) | random32(); 122 } 123 124 switch (conflen) { 125 case 16: 126 *q++ = i++; 127 /* fall through */ 128 case 8: 129 *q++ = i++; 130 break; 131 default: 132 BUG(); 133 } 134} 135 136/* Assumptions: the head and tail of inbuf are ours to play with. 137 * The pages, however, may be real pages in the page cache and we replace 138 * them with scratch pages from **pages before writing to them. */ 139 140 141static u32 142gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset, 143 struct xdr_buf *buf, struct page **pages) 144{ 145 char cksumdata[GSS_KRB5_MAX_CKSUM_LEN]; 146 struct xdr_netobj md5cksum = {.len = sizeof(cksumdata), 147 .data = cksumdata}; 148 int blocksize = 0, plainlen; 149 unsigned char *ptr, *msg_start; 150 s32 now; 151 int headlen; 152 struct page **tmp_pages; 153 u32 seq_send; 154 u8 *cksumkey; 155 u32 conflen = kctx->gk5e->conflen; 156 157 dprintk("RPC: %s\n", __func__); 158 159 now = get_seconds(); 160 161 blocksize = crypto_blkcipher_blocksize(kctx->enc); 162 gss_krb5_add_padding(buf, offset, blocksize); 163 BUG_ON((buf->len - offset) % blocksize); 164 plainlen = conflen + buf->len - offset; 165 166 headlen = g_token_size(&kctx->mech_used, 167 GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength + plainlen) - 168 (buf->len - offset); 169 170 ptr = buf->head[0].iov_base + offset; 171 /* shift data to make room for header. */ 172 xdr_extend_head(buf, offset, headlen); 173 174 BUG_ON((buf->len - offset - headlen) % blocksize); 175 176 g_make_token_header(&kctx->mech_used, 177 GSS_KRB5_TOK_HDR_LEN + 178 kctx->gk5e->cksumlength + plainlen, &ptr); 179 180 181 /* ptr now at header described in rfc 1964, section 1.2.1: */ 182 ptr[0] = (unsigned char) ((KG_TOK_WRAP_MSG >> 8) & 0xff); 183 ptr[1] = (unsigned char) (KG_TOK_WRAP_MSG & 0xff); 184 185 msg_start = ptr + GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength; 186 187 *(__be16 *)(ptr + 2) = cpu_to_le16(kctx->gk5e->signalg); 188 memset(ptr + 4, 0xff, 4); 189 *(__be16 *)(ptr + 4) = cpu_to_le16(kctx->gk5e->sealalg); 190 191 gss_krb5_make_confounder(msg_start, conflen); 192 193 if (kctx->gk5e->keyed_cksum) 194 cksumkey = kctx->cksum; 195 else 196 cksumkey = NULL; 197 198 /* XXXJBF: UGH!: */ 199 tmp_pages = buf->pages; 200 buf->pages = pages; 201 if (make_checksum(kctx, ptr, 8, buf, offset + headlen - conflen, 202 cksumkey, KG_USAGE_SEAL, &md5cksum)) 203 return GSS_S_FAILURE; 204 buf->pages = tmp_pages; 205 206 memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len); 207 208 spin_lock(&krb5_seq_lock); 209 seq_send = kctx->seq_send++; 210 spin_unlock(&krb5_seq_lock); 211 212 if ((krb5_make_seq_num(kctx, kctx->seq, kctx->initiate ? 0 : 0xff, 213 seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8))) 214 return GSS_S_FAILURE; 215 216 if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC) { 217 struct crypto_blkcipher *cipher; 218 int err; 219 cipher = crypto_alloc_blkcipher(kctx->gk5e->encrypt_name, 0, 220 CRYPTO_ALG_ASYNC); 221 if (IS_ERR(cipher)) 222 return GSS_S_FAILURE; 223 224 krb5_rc4_setup_enc_key(kctx, cipher, seq_send); 225 226 err = gss_encrypt_xdr_buf(cipher, buf, 227 offset + headlen - conflen, pages); 228 crypto_free_blkcipher(cipher); 229 if (err) 230 return GSS_S_FAILURE; 231 } else { 232 if (gss_encrypt_xdr_buf(kctx->enc, buf, 233 offset + headlen - conflen, pages)) 234 return GSS_S_FAILURE; 235 } 236 237 return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE; 238} 239 240static u32 241gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf) 242{ 243 int signalg; 244 int sealalg; 245 char cksumdata[GSS_KRB5_MAX_CKSUM_LEN]; 246 struct xdr_netobj md5cksum = {.len = sizeof(cksumdata), 247 .data = cksumdata}; 248 s32 now; 249 int direction; 250 s32 seqnum; 251 unsigned char *ptr; 252 int bodysize; 253 void *data_start, *orig_start; 254 int data_len; 255 int blocksize; 256 u32 conflen = kctx->gk5e->conflen; 257 int crypt_offset; 258 u8 *cksumkey; 259 260 dprintk("RPC: gss_unwrap_kerberos\n"); 261 262 ptr = (u8 *)buf->head[0].iov_base + offset; 263 if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr, 264 buf->len - offset)) 265 return GSS_S_DEFECTIVE_TOKEN; 266 267 if ((ptr[0] != ((KG_TOK_WRAP_MSG >> 8) & 0xff)) || 268 (ptr[1] != (KG_TOK_WRAP_MSG & 0xff))) 269 return GSS_S_DEFECTIVE_TOKEN; 270 271 272 /* get the sign and seal algorithms */ 273 274 signalg = ptr[2] + (ptr[3] << 8); 275 if (signalg != kctx->gk5e->signalg) 276 return GSS_S_DEFECTIVE_TOKEN; 277 278 sealalg = ptr[4] + (ptr[5] << 8); 279 if (sealalg != kctx->gk5e->sealalg) 280 return GSS_S_DEFECTIVE_TOKEN; 281 282 if ((ptr[6] != 0xff) || (ptr[7] != 0xff)) 283 return GSS_S_DEFECTIVE_TOKEN; 284 285 /* 286 * Data starts after token header and checksum. ptr points 287 * to the beginning of the token header 288 */ 289 crypt_offset = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) - 290 (unsigned char *)buf->head[0].iov_base; 291 292 /* 293 * Need plaintext seqnum to derive encryption key for arcfour-hmac 294 */ 295 if (krb5_get_seq_num(kctx, ptr + GSS_KRB5_TOK_HDR_LEN, 296 ptr + 8, &direction, &seqnum)) 297 return GSS_S_BAD_SIG; 298 299 if ((kctx->initiate && direction != 0xff) || 300 (!kctx->initiate && direction != 0)) 301 return GSS_S_BAD_SIG; 302 303 if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC) { 304 struct crypto_blkcipher *cipher; 305 int err; 306 307 cipher = crypto_alloc_blkcipher(kctx->gk5e->encrypt_name, 0, 308 CRYPTO_ALG_ASYNC); 309 if (IS_ERR(cipher)) 310 return GSS_S_FAILURE; 311 312 krb5_rc4_setup_enc_key(kctx, cipher, seqnum); 313 314 err = gss_decrypt_xdr_buf(cipher, buf, crypt_offset); 315 crypto_free_blkcipher(cipher); 316 if (err) 317 return GSS_S_DEFECTIVE_TOKEN; 318 } else { 319 if (gss_decrypt_xdr_buf(kctx->enc, buf, crypt_offset)) 320 return GSS_S_DEFECTIVE_TOKEN; 321 } 322 323 if (kctx->gk5e->keyed_cksum) 324 cksumkey = kctx->cksum; 325 else 326 cksumkey = NULL; 327 328 if (make_checksum(kctx, ptr, 8, buf, crypt_offset, 329 cksumkey, KG_USAGE_SEAL, &md5cksum)) 330 return GSS_S_FAILURE; 331 332 if (memcmp(md5cksum.data, ptr + GSS_KRB5_TOK_HDR_LEN, 333 kctx->gk5e->cksumlength)) 334 return GSS_S_BAD_SIG; 335 336 /* it got through unscathed. Make sure the context is unexpired */ 337 338 now = get_seconds(); 339 340 if (now > kctx->endtime) 341 return GSS_S_CONTEXT_EXPIRED; 342 343 /* do sequencing checks */ 344 345 346 blocksize = crypto_blkcipher_blocksize(kctx->enc); 347 data_start = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) + 348 conflen; 349 orig_start = buf->head[0].iov_base + offset; 350 data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start; 351 memmove(orig_start, data_start, data_len); 352 buf->head[0].iov_len -= (data_start - orig_start); 353 buf->len -= (data_start - orig_start); 354 355 if (gss_krb5_remove_padding(buf, blocksize)) 356 return GSS_S_DEFECTIVE_TOKEN; 357 358 return GSS_S_COMPLETE; 359} 360 361/* 362 * We cannot currently handle tokens with rotated data. We need a 363 * generalized routine to rotate the data in place. It is anticipated 364 * that we won't encounter rotated data in the general case. 365 */ 366static u32 367rotate_left(struct krb5_ctx *kctx, u32 offset, struct xdr_buf *buf, u16 rrc) 368{ 369 unsigned int realrrc = rrc % (buf->len - offset - GSS_KRB5_TOK_HDR_LEN); 370 371 if (realrrc == 0) 372 return 0; 373 374 dprintk("%s: cannot process token with rotated data: " 375 "rrc %u, realrrc %u\n", __func__, rrc, realrrc); 376 return 1; 377} 378 379static u32 380gss_wrap_kerberos_v2(struct krb5_ctx *kctx, u32 offset, 381 struct xdr_buf *buf, struct page **pages) 382{ 383 int blocksize; 384 u8 *ptr, *plainhdr; 385 s32 now; 386 u8 flags = 0x00; 387 __be16 *be16ptr, ec = 0; 388 __be64 *be64ptr; 389 u32 err; 390 391 dprintk("RPC: %s\n", __func__); 392 393 if (kctx->gk5e->encrypt_v2 == NULL) 394 return GSS_S_FAILURE; 395 396 /* make room for gss token header */ 397 if (xdr_extend_head(buf, offset, GSS_KRB5_TOK_HDR_LEN)) 398 return GSS_S_FAILURE; 399 400 /* construct gss token header */ 401 ptr = plainhdr = buf->head[0].iov_base + offset; 402 *ptr++ = (unsigned char) ((KG2_TOK_WRAP>>8) & 0xff); 403 *ptr++ = (unsigned char) (KG2_TOK_WRAP & 0xff); 404 405 if ((kctx->flags & KRB5_CTX_FLAG_INITIATOR) == 0) 406 flags |= KG2_TOKEN_FLAG_SENTBYACCEPTOR; 407 if ((kctx->flags & KRB5_CTX_FLAG_ACCEPTOR_SUBKEY) != 0) 408 flags |= KG2_TOKEN_FLAG_ACCEPTORSUBKEY; 409 /* We always do confidentiality in wrap tokens */ 410 flags |= KG2_TOKEN_FLAG_SEALED; 411 412 *ptr++ = flags; 413 *ptr++ = 0xff; 414 be16ptr = (__be16 *)ptr; 415 416 blocksize = crypto_blkcipher_blocksize(kctx->acceptor_enc); 417 *be16ptr++ = cpu_to_be16(ec); 418 /* "inner" token header always uses 0 for RRC */ 419 *be16ptr++ = cpu_to_be16(0); 420 421 be64ptr = (__be64 *)be16ptr; 422 spin_lock(&krb5_seq_lock); 423 *be64ptr = cpu_to_be64(kctx->seq_send64++); 424 spin_unlock(&krb5_seq_lock); 425 426 err = (*kctx->gk5e->encrypt_v2)(kctx, offset, buf, ec, pages); 427 if (err) 428 return err; 429 430 now = get_seconds(); 431 return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE; 432} 433 434static u32 435gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf) 436{ 437 s32 now; 438 u64 seqnum; 439 u8 *ptr; 440 u8 flags = 0x00; 441 u16 ec, rrc; 442 int err; 443 u32 headskip, tailskip; 444 u8 decrypted_hdr[GSS_KRB5_TOK_HDR_LEN]; 445 unsigned int movelen; 446 447 448 dprintk("RPC: %s\n", __func__); 449 450 if (kctx->gk5e->decrypt_v2 == NULL) 451 return GSS_S_FAILURE; 452 453 ptr = buf->head[0].iov_base + offset; 454 455 if (be16_to_cpu(*((__be16 *)ptr)) != KG2_TOK_WRAP) 456 return GSS_S_DEFECTIVE_TOKEN; 457 458 flags = ptr[2]; 459 if ((!kctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) || 460 (kctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR))) 461 return GSS_S_BAD_SIG; 462 463 if ((flags & KG2_TOKEN_FLAG_SEALED) == 0) { 464 dprintk("%s: token missing expected sealed flag\n", __func__); 465 return GSS_S_DEFECTIVE_TOKEN; 466 } 467 468 if (ptr[3] != 0xff) 469 return GSS_S_DEFECTIVE_TOKEN; 470 471 ec = be16_to_cpup((__be16 *)(ptr + 4)); 472 rrc = be16_to_cpup((__be16 *)(ptr + 6)); 473 474 seqnum = be64_to_cpup((__be64 *)(ptr + 8)); 475 476 if (rrc != 0) { 477 err = rotate_left(kctx, offset, buf, rrc); 478 if (err) 479 return GSS_S_FAILURE; 480 } 481 482 err = (*kctx->gk5e->decrypt_v2)(kctx, offset, buf, 483 &headskip, &tailskip); 484 if (err) 485 return GSS_S_FAILURE; 486 487 /* 488 * Retrieve the decrypted gss token header and verify 489 * it against the original 490 */ 491 err = read_bytes_from_xdr_buf(buf, 492 buf->len - GSS_KRB5_TOK_HDR_LEN - tailskip, 493 decrypted_hdr, GSS_KRB5_TOK_HDR_LEN); 494 if (err) { 495 dprintk("%s: error %u getting decrypted_hdr\n", __func__, err); 496 return GSS_S_FAILURE; 497 } 498 if (memcmp(ptr, decrypted_hdr, 6) 499 || memcmp(ptr + 8, decrypted_hdr + 8, 8)) { 500 dprintk("%s: token hdr, plaintext hdr mismatch!\n", __func__); 501 return GSS_S_FAILURE; 502 } 503 504 /* do sequencing checks */ 505 506 /* it got through unscathed. Make sure the context is unexpired */ 507 now = get_seconds(); 508 if (now > kctx->endtime) 509 return GSS_S_CONTEXT_EXPIRED; 510 511 /* 512 * Move the head data back to the right position in xdr_buf. 513 * We ignore any "ec" data since it might be in the head or 514 * the tail, and we really don't need to deal with it. 515 * Note that buf->head[0].iov_len may indicate the available 516 * head buffer space rather than that actually occupied. 517 */ 518 movelen = min_t(unsigned int, buf->head[0].iov_len, buf->len); 519 movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip; 520 BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen > 521 buf->head[0].iov_len); 522 memmove(ptr, ptr + GSS_KRB5_TOK_HDR_LEN + headskip, movelen); 523 buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip; 524 buf->len -= GSS_KRB5_TOK_HDR_LEN + headskip; 525 526 return GSS_S_COMPLETE; 527} 528 529u32 530gss_wrap_kerberos(struct gss_ctx *gctx, int offset, 531 struct xdr_buf *buf, struct page **pages) 532{ 533 struct krb5_ctx *kctx = gctx->internal_ctx_id; 534 535 switch (kctx->enctype) { 536 default: 537 BUG(); 538 case ENCTYPE_DES_CBC_RAW: 539 case ENCTYPE_DES3_CBC_RAW: 540 case ENCTYPE_ARCFOUR_HMAC: 541 return gss_wrap_kerberos_v1(kctx, offset, buf, pages); 542 case ENCTYPE_AES128_CTS_HMAC_SHA1_96: 543 case ENCTYPE_AES256_CTS_HMAC_SHA1_96: 544 return gss_wrap_kerberos_v2(kctx, offset, buf, pages); 545 } 546} 547 548u32 549gss_unwrap_kerberos(struct gss_ctx *gctx, int offset, struct xdr_buf *buf) 550{ 551 struct krb5_ctx *kctx = gctx->internal_ctx_id; 552 553 switch (kctx->enctype) { 554 default: 555 BUG(); 556 case ENCTYPE_DES_CBC_RAW: 557 case ENCTYPE_DES3_CBC_RAW: 558 case ENCTYPE_ARCFOUR_HMAC: 559 return gss_unwrap_kerberos_v1(kctx, offset, buf); 560 case ENCTYPE_AES128_CTS_HMAC_SHA1_96: 561 case ENCTYPE_AES256_CTS_HMAC_SHA1_96: 562 return gss_unwrap_kerberos_v2(kctx, offset, buf); 563 } 564} 565