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 <crypto/skcipher.h> 32 #include <linux/types.h> 33 #include <linux/jiffies.h> 34 #include <linux/sunrpc/gss_krb5.h> 35 #include <linux/random.h> 36 #include <linux/pagemap.h> 37 38 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG) 39 # define RPCDBG_FACILITY RPCDBG_AUTH 40 #endif 41 42 static inline int 43 gss_krb5_padding(int blocksize, int length) 44 { 45 return blocksize - (length % blocksize); 46 } 47 48 static inline void 49 gss_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 65 static inline int 66 gss_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_SHIFT; 83 unsigned int offset = (buf->page_base + len - 1) 84 & (PAGE_SIZE - 1); 85 ptr = kmap_atomic(buf->pages[last]); 86 pad = *(ptr + offset); 87 kunmap_atomic(ptr); 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); 93 out: 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 } 115 116 void 117 gss_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 = get_random_u32(); 134 i = (i << 32) | get_random_u32(); 135 } 136 137 switch (conflen) { 138 case 16: 139 *q++ = i++; 140 fallthrough; 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. */ 156 157 static u32 158 gss_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 time64_t 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 = ktime_get_real_seconds(); 176 177 blocksize = crypto_sync_skcipher_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 /* 205 * signalg and sealalg are stored as if they were converted from LE 206 * to host endian, even though they're opaque pairs of bytes according 207 * to the RFC. 208 */ 209 *(__le16 *)(ptr + 2) = cpu_to_le16(kctx->gk5e->signalg); 210 *(__le16 *)(ptr + 4) = cpu_to_le16(kctx->gk5e->sealalg); 211 ptr[6] = 0xff; 212 ptr[7] = 0xff; 213 214 gss_krb5_make_confounder(msg_start, conflen); 215 216 if (kctx->gk5e->keyed_cksum) 217 cksumkey = kctx->cksum; 218 else 219 cksumkey = NULL; 220 221 /* XXXJBF: UGH!: */ 222 tmp_pages = buf->pages; 223 buf->pages = pages; 224 if (make_checksum(kctx, ptr, 8, buf, offset + headlen - conflen, 225 cksumkey, KG_USAGE_SEAL, &md5cksum)) 226 return GSS_S_FAILURE; 227 buf->pages = tmp_pages; 228 229 memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len); 230 231 seq_send = atomic_fetch_inc(&kctx->seq_send); 232 233 /* XXX would probably be more efficient to compute checksum 234 * and encrypt at the same time: */ 235 if ((krb5_make_seq_num(kctx, kctx->seq, kctx->initiate ? 0 : 0xff, 236 seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8))) 237 return GSS_S_FAILURE; 238 239 if (gss_encrypt_xdr_buf(kctx->enc, buf, 240 offset + headlen - conflen, pages)) 241 return GSS_S_FAILURE; 242 243 return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE; 244 } 245 246 static u32 247 gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, int len, 248 struct xdr_buf *buf, unsigned int *slack, 249 unsigned int *align) 250 { 251 int signalg; 252 int sealalg; 253 char cksumdata[GSS_KRB5_MAX_CKSUM_LEN]; 254 struct xdr_netobj md5cksum = {.len = sizeof(cksumdata), 255 .data = cksumdata}; 256 time64_t now; 257 int direction; 258 s32 seqnum; 259 unsigned char *ptr; 260 int bodysize; 261 void *data_start, *orig_start; 262 int data_len; 263 int blocksize; 264 u32 conflen = kctx->gk5e->conflen; 265 int crypt_offset; 266 u8 *cksumkey; 267 unsigned int saved_len = buf->len; 268 269 dprintk("RPC: gss_unwrap_kerberos\n"); 270 271 ptr = (u8 *)buf->head[0].iov_base + offset; 272 if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr, 273 len - offset)) 274 return GSS_S_DEFECTIVE_TOKEN; 275 276 if ((ptr[0] != ((KG_TOK_WRAP_MSG >> 8) & 0xff)) || 277 (ptr[1] != (KG_TOK_WRAP_MSG & 0xff))) 278 return GSS_S_DEFECTIVE_TOKEN; 279 280 /* XXX sanity-check bodysize?? */ 281 282 /* get the sign and seal algorithms */ 283 284 signalg = ptr[2] + (ptr[3] << 8); 285 if (signalg != kctx->gk5e->signalg) 286 return GSS_S_DEFECTIVE_TOKEN; 287 288 sealalg = ptr[4] + (ptr[5] << 8); 289 if (sealalg != kctx->gk5e->sealalg) 290 return GSS_S_DEFECTIVE_TOKEN; 291 292 if ((ptr[6] != 0xff) || (ptr[7] != 0xff)) 293 return GSS_S_DEFECTIVE_TOKEN; 294 295 /* 296 * Data starts after token header and checksum. ptr points 297 * to the beginning of the token header 298 */ 299 crypt_offset = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) - 300 (unsigned char *)buf->head[0].iov_base; 301 302 buf->len = len; 303 if (gss_decrypt_xdr_buf(kctx->enc, buf, crypt_offset)) 304 return GSS_S_DEFECTIVE_TOKEN; 305 306 if (kctx->gk5e->keyed_cksum) 307 cksumkey = kctx->cksum; 308 else 309 cksumkey = NULL; 310 311 if (make_checksum(kctx, ptr, 8, buf, crypt_offset, 312 cksumkey, KG_USAGE_SEAL, &md5cksum)) 313 return GSS_S_FAILURE; 314 315 if (memcmp(md5cksum.data, ptr + GSS_KRB5_TOK_HDR_LEN, 316 kctx->gk5e->cksumlength)) 317 return GSS_S_BAD_SIG; 318 319 /* it got through unscathed. Make sure the context is unexpired */ 320 321 now = ktime_get_real_seconds(); 322 323 if (now > kctx->endtime) 324 return GSS_S_CONTEXT_EXPIRED; 325 326 /* do sequencing checks */ 327 328 if (krb5_get_seq_num(kctx, ptr + GSS_KRB5_TOK_HDR_LEN, 329 ptr + 8, &direction, &seqnum)) 330 return GSS_S_BAD_SIG; 331 332 if ((kctx->initiate && direction != 0xff) || 333 (!kctx->initiate && direction != 0)) 334 return GSS_S_BAD_SIG; 335 336 /* Copy the data back to the right position. XXX: Would probably be 337 * better to copy and encrypt at the same time. */ 338 339 blocksize = crypto_sync_skcipher_blocksize(kctx->enc); 340 data_start = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) + 341 conflen; 342 orig_start = buf->head[0].iov_base + offset; 343 data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start; 344 memmove(orig_start, data_start, data_len); 345 buf->head[0].iov_len -= (data_start - orig_start); 346 buf->len = len - (data_start - orig_start); 347 348 if (gss_krb5_remove_padding(buf, blocksize)) 349 return GSS_S_DEFECTIVE_TOKEN; 350 351 /* slack must include room for krb5 padding */ 352 *slack = XDR_QUADLEN(saved_len - buf->len); 353 /* The GSS blob always precedes the RPC message payload */ 354 *align = *slack; 355 return GSS_S_COMPLETE; 356 } 357 358 /* 359 * We can shift data by up to LOCAL_BUF_LEN bytes in a pass. If we need 360 * to do more than that, we shift repeatedly. Kevin Coffman reports 361 * seeing 28 bytes as the value used by Microsoft clients and servers 362 * with AES, so this constant is chosen to allow handling 28 in one pass 363 * without using too much stack space. 364 * 365 * If that proves to a problem perhaps we could use a more clever 366 * algorithm. 367 */ 368 #define LOCAL_BUF_LEN 32u 369 370 static void rotate_buf_a_little(struct xdr_buf *buf, unsigned int shift) 371 { 372 char head[LOCAL_BUF_LEN]; 373 char tmp[LOCAL_BUF_LEN]; 374 unsigned int this_len, i; 375 376 BUG_ON(shift > LOCAL_BUF_LEN); 377 378 read_bytes_from_xdr_buf(buf, 0, head, shift); 379 for (i = 0; i + shift < buf->len; i += LOCAL_BUF_LEN) { 380 this_len = min(LOCAL_BUF_LEN, buf->len - (i + shift)); 381 read_bytes_from_xdr_buf(buf, i+shift, tmp, this_len); 382 write_bytes_to_xdr_buf(buf, i, tmp, this_len); 383 } 384 write_bytes_to_xdr_buf(buf, buf->len - shift, head, shift); 385 } 386 387 static void _rotate_left(struct xdr_buf *buf, unsigned int shift) 388 { 389 int shifted = 0; 390 int this_shift; 391 392 shift %= buf->len; 393 while (shifted < shift) { 394 this_shift = min(shift - shifted, LOCAL_BUF_LEN); 395 rotate_buf_a_little(buf, this_shift); 396 shifted += this_shift; 397 } 398 } 399 400 static void rotate_left(u32 base, struct xdr_buf *buf, unsigned int shift) 401 { 402 struct xdr_buf subbuf; 403 404 xdr_buf_subsegment(buf, &subbuf, base, buf->len - base); 405 _rotate_left(&subbuf, shift); 406 } 407 408 static u32 409 gss_wrap_kerberos_v2(struct krb5_ctx *kctx, u32 offset, 410 struct xdr_buf *buf, struct page **pages) 411 { 412 u8 *ptr; 413 time64_t now; 414 u8 flags = 0x00; 415 __be16 *be16ptr; 416 __be64 *be64ptr; 417 u32 err; 418 419 dprintk("RPC: %s\n", __func__); 420 421 if (kctx->gk5e->encrypt_v2 == NULL) 422 return GSS_S_FAILURE; 423 424 /* make room for gss token header */ 425 if (xdr_extend_head(buf, offset, GSS_KRB5_TOK_HDR_LEN)) 426 return GSS_S_FAILURE; 427 428 /* construct gss token header */ 429 ptr = buf->head[0].iov_base + offset; 430 *ptr++ = (unsigned char) ((KG2_TOK_WRAP>>8) & 0xff); 431 *ptr++ = (unsigned char) (KG2_TOK_WRAP & 0xff); 432 433 if ((kctx->flags & KRB5_CTX_FLAG_INITIATOR) == 0) 434 flags |= KG2_TOKEN_FLAG_SENTBYACCEPTOR; 435 if ((kctx->flags & KRB5_CTX_FLAG_ACCEPTOR_SUBKEY) != 0) 436 flags |= KG2_TOKEN_FLAG_ACCEPTORSUBKEY; 437 /* We always do confidentiality in wrap tokens */ 438 flags |= KG2_TOKEN_FLAG_SEALED; 439 440 *ptr++ = flags; 441 *ptr++ = 0xff; 442 be16ptr = (__be16 *)ptr; 443 444 *be16ptr++ = 0; 445 /* "inner" token header always uses 0 for RRC */ 446 *be16ptr++ = 0; 447 448 be64ptr = (__be64 *)be16ptr; 449 *be64ptr = cpu_to_be64(atomic64_fetch_inc(&kctx->seq_send64)); 450 451 err = (*kctx->gk5e->encrypt_v2)(kctx, offset, buf, pages); 452 if (err) 453 return err; 454 455 now = ktime_get_real_seconds(); 456 return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE; 457 } 458 459 static u32 460 gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, int len, 461 struct xdr_buf *buf, unsigned int *slack, 462 unsigned int *align) 463 { 464 time64_t now; 465 u8 *ptr; 466 u8 flags = 0x00; 467 u16 ec, rrc; 468 int err; 469 u32 headskip, tailskip; 470 u8 decrypted_hdr[GSS_KRB5_TOK_HDR_LEN]; 471 unsigned int movelen; 472 473 474 dprintk("RPC: %s\n", __func__); 475 476 if (kctx->gk5e->decrypt_v2 == NULL) 477 return GSS_S_FAILURE; 478 479 ptr = buf->head[0].iov_base + offset; 480 481 if (be16_to_cpu(*((__be16 *)ptr)) != KG2_TOK_WRAP) 482 return GSS_S_DEFECTIVE_TOKEN; 483 484 flags = ptr[2]; 485 if ((!kctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) || 486 (kctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR))) 487 return GSS_S_BAD_SIG; 488 489 if ((flags & KG2_TOKEN_FLAG_SEALED) == 0) { 490 dprintk("%s: token missing expected sealed flag\n", __func__); 491 return GSS_S_DEFECTIVE_TOKEN; 492 } 493 494 if (ptr[3] != 0xff) 495 return GSS_S_DEFECTIVE_TOKEN; 496 497 ec = be16_to_cpup((__be16 *)(ptr + 4)); 498 rrc = be16_to_cpup((__be16 *)(ptr + 6)); 499 500 /* 501 * NOTE: the sequence number at ptr + 8 is skipped, rpcsec_gss 502 * doesn't want it checked; see page 6 of rfc 2203. 503 */ 504 505 if (rrc != 0) 506 rotate_left(offset + 16, buf, rrc); 507 508 err = (*kctx->gk5e->decrypt_v2)(kctx, offset, len, buf, 509 &headskip, &tailskip); 510 if (err) 511 return GSS_S_FAILURE; 512 513 /* 514 * Retrieve the decrypted gss token header and verify 515 * it against the original 516 */ 517 err = read_bytes_from_xdr_buf(buf, 518 len - GSS_KRB5_TOK_HDR_LEN - tailskip, 519 decrypted_hdr, GSS_KRB5_TOK_HDR_LEN); 520 if (err) { 521 dprintk("%s: error %u getting decrypted_hdr\n", __func__, err); 522 return GSS_S_FAILURE; 523 } 524 if (memcmp(ptr, decrypted_hdr, 6) 525 || memcmp(ptr + 8, decrypted_hdr + 8, 8)) { 526 dprintk("%s: token hdr, plaintext hdr mismatch!\n", __func__); 527 return GSS_S_FAILURE; 528 } 529 530 /* do sequencing checks */ 531 532 /* it got through unscathed. Make sure the context is unexpired */ 533 now = ktime_get_real_seconds(); 534 if (now > kctx->endtime) 535 return GSS_S_CONTEXT_EXPIRED; 536 537 /* 538 * Move the head data back to the right position in xdr_buf. 539 * We ignore any "ec" data since it might be in the head or 540 * the tail, and we really don't need to deal with it. 541 * Note that buf->head[0].iov_len may indicate the available 542 * head buffer space rather than that actually occupied. 543 */ 544 movelen = min_t(unsigned int, buf->head[0].iov_len, len); 545 movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip; 546 BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen > 547 buf->head[0].iov_len); 548 memmove(ptr, ptr + GSS_KRB5_TOK_HDR_LEN + headskip, movelen); 549 buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip; 550 buf->len = len - (GSS_KRB5_TOK_HDR_LEN + headskip); 551 552 /* Trim off the trailing "extra count" and checksum blob */ 553 xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip); 554 555 *align = XDR_QUADLEN(GSS_KRB5_TOK_HDR_LEN + headskip); 556 *slack = *align + XDR_QUADLEN(ec + GSS_KRB5_TOK_HDR_LEN + tailskip); 557 return GSS_S_COMPLETE; 558 } 559 560 u32 561 gss_wrap_kerberos(struct gss_ctx *gctx, int offset, 562 struct xdr_buf *buf, struct page **pages) 563 { 564 struct krb5_ctx *kctx = gctx->internal_ctx_id; 565 566 switch (kctx->enctype) { 567 default: 568 BUG(); 569 case ENCTYPE_DES_CBC_RAW: 570 case ENCTYPE_DES3_CBC_RAW: 571 return gss_wrap_kerberos_v1(kctx, offset, buf, pages); 572 case ENCTYPE_AES128_CTS_HMAC_SHA1_96: 573 case ENCTYPE_AES256_CTS_HMAC_SHA1_96: 574 return gss_wrap_kerberos_v2(kctx, offset, buf, pages); 575 } 576 } 577 578 u32 579 gss_unwrap_kerberos(struct gss_ctx *gctx, int offset, 580 int len, struct xdr_buf *buf) 581 { 582 struct krb5_ctx *kctx = gctx->internal_ctx_id; 583 584 switch (kctx->enctype) { 585 default: 586 BUG(); 587 case ENCTYPE_DES_CBC_RAW: 588 case ENCTYPE_DES3_CBC_RAW: 589 return gss_unwrap_kerberos_v1(kctx, offset, len, buf, 590 &gctx->slack, &gctx->align); 591 case ENCTYPE_AES128_CTS_HMAC_SHA1_96: 592 case ENCTYPE_AES256_CTS_HMAC_SHA1_96: 593 return gss_unwrap_kerberos_v2(kctx, offset, len, buf, 594 &gctx->slack, &gctx->align); 595 } 596 } 597