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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>
39 # define RPCDBG_FACILITY RPCDBG_AUTH
43 gss_krb5_padding(int blocksize, int length)
45 return blocksize - (length % blocksize);
49 gss_krb5_add_padding(struct xdr_buf *buf, int offset, int blocksize)
51 int padding = gss_krb5_padding(blocksize, buf->len - offset);
55 if (buf->page_len || buf->tail[0].iov_len)
59 p = iov->iov_base + iov->iov_len;
60 iov->iov_len += padding;
62 memset(p, padding, padding);
66 gss_krb5_remove_padding(struct xdr_buf *buf, int blocksize)
70 size_t len = buf->len;
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)
76 buf->head[0].iov_len -= pad;
79 len -= buf->head[0].iov_len;
80 if (len <= buf->page_len) {
81 unsigned int last = (buf->page_base + len - 1)
83 unsigned int offset = (buf->page_base + len - 1)
84 & (PAGE_CACHE_SIZE - 1);
85 ptr = kmap_atomic(buf->pages[last]);
86 pad = *(ptr + offset);
91 BUG_ON(len > buf->tail[0].iov_len);
92 pad = *(u8 *)(buf->tail[0].iov_base + len - 1);
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. */
117 gss_krb5_make_confounder(char *p, u32 conflen)
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. */
131 /* initialize to random value */
134 i = (i << 32) | prandom_u32();
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. */
155 /* XXX factor out common code with seal/unseal. */
158 gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset,
159 struct xdr_buf *buf, struct page **pages)
161 char cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
162 struct xdr_netobj md5cksum = {.len = sizeof(cksumdata),
164 int blocksize = 0, plainlen;
165 unsigned char *ptr, *msg_start;
168 struct page **tmp_pages;
171 u32 conflen = kctx->gk5e->conflen;
173 dprintk("RPC: %s\n", __func__);
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;
182 headlen = g_token_size(&kctx->mech_used,
183 GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength + plainlen) -
186 ptr = buf->head[0].iov_base + offset;
187 /* shift data to make room for header. */
188 xdr_extend_head(buf, offset, headlen);
190 /* XXX Would be cleverer to encrypt while copying. */
191 BUG_ON((buf->len - offset - headlen) % blocksize);
193 g_make_token_header(&kctx->mech_used,
194 GSS_KRB5_TOK_HDR_LEN +
195 kctx->gk5e->cksumlength + plainlen, &ptr);
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);
202 msg_start = ptr + GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength;
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);
208 gss_krb5_make_confounder(msg_start, conflen);
210 if (kctx->gk5e->keyed_cksum)
211 cksumkey = kctx->cksum;
216 tmp_pages = buf->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;
223 memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len);
225 spin_lock(&krb5_seq_lock);
226 seq_send = kctx->seq_send++;
227 spin_unlock(&krb5_seq_lock);
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;
235 if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC) {
236 struct crypto_blkcipher *cipher;
238 cipher = crypto_alloc_blkcipher(kctx->gk5e->encrypt_name, 0,
241 return GSS_S_FAILURE;
243 krb5_rc4_setup_enc_key(kctx, cipher, seq_send);
245 err = gss_encrypt_xdr_buf(cipher, buf,
246 offset + headlen - conflen, pages);
247 crypto_free_blkcipher(cipher);
249 return GSS_S_FAILURE;
251 if (gss_encrypt_xdr_buf(kctx->enc, buf,
252 offset + headlen - conflen, pages))
253 return GSS_S_FAILURE;
256 return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
260 gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf)
264 char cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
265 struct xdr_netobj md5cksum = {.len = sizeof(cksumdata),
272 void *data_start, *orig_start;
275 u32 conflen = kctx->gk5e->conflen;
279 dprintk("RPC: gss_unwrap_kerberos\n");
281 ptr = (u8 *)buf->head[0].iov_base + offset;
282 if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr,
284 return GSS_S_DEFECTIVE_TOKEN;
286 if ((ptr[0] != ((KG_TOK_WRAP_MSG >> 8) & 0xff)) ||
287 (ptr[1] != (KG_TOK_WRAP_MSG & 0xff)))
288 return GSS_S_DEFECTIVE_TOKEN;
290 /* XXX sanity-check bodysize?? */
292 /* get the sign and seal algorithms */
294 signalg = ptr[2] + (ptr[3] << 8);
295 if (signalg != kctx->gk5e->signalg)
296 return GSS_S_DEFECTIVE_TOKEN;
298 sealalg = ptr[4] + (ptr[5] << 8);
299 if (sealalg != kctx->gk5e->sealalg)
300 return GSS_S_DEFECTIVE_TOKEN;
302 if ((ptr[6] != 0xff) || (ptr[7] != 0xff))
303 return GSS_S_DEFECTIVE_TOKEN;
306 * Data starts after token header and checksum. ptr points
307 * to the beginning of the token header
309 crypt_offset = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) -
310 (unsigned char *)buf->head[0].iov_base;
313 * Need plaintext seqnum to derive encryption key for arcfour-hmac
315 if (krb5_get_seq_num(kctx, ptr + GSS_KRB5_TOK_HDR_LEN,
316 ptr + 8, &direction, &seqnum))
317 return GSS_S_BAD_SIG;
319 if ((kctx->initiate && direction != 0xff) ||
320 (!kctx->initiate && direction != 0))
321 return GSS_S_BAD_SIG;
323 if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC) {
324 struct crypto_blkcipher *cipher;
327 cipher = crypto_alloc_blkcipher(kctx->gk5e->encrypt_name, 0,
330 return GSS_S_FAILURE;
332 krb5_rc4_setup_enc_key(kctx, cipher, seqnum);
334 err = gss_decrypt_xdr_buf(cipher, buf, crypt_offset);
335 crypto_free_blkcipher(cipher);
337 return GSS_S_DEFECTIVE_TOKEN;
339 if (gss_decrypt_xdr_buf(kctx->enc, buf, crypt_offset))
340 return GSS_S_DEFECTIVE_TOKEN;
343 if (kctx->gk5e->keyed_cksum)
344 cksumkey = kctx->cksum;
348 if (make_checksum(kctx, ptr, 8, buf, crypt_offset,
349 cksumkey, KG_USAGE_SEAL, &md5cksum))
350 return GSS_S_FAILURE;
352 if (memcmp(md5cksum.data, ptr + GSS_KRB5_TOK_HDR_LEN,
353 kctx->gk5e->cksumlength))
354 return GSS_S_BAD_SIG;
356 /* it got through unscathed. Make sure the context is unexpired */
360 if (now > kctx->endtime)
361 return GSS_S_CONTEXT_EXPIRED;
363 /* do sequencing checks */
365 /* Copy the data back to the right position. XXX: Would probably be
366 * better to copy and encrypt at the same time. */
368 blocksize = crypto_blkcipher_blocksize(kctx->enc);
369 data_start = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) +
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);
377 if (gss_krb5_remove_padding(buf, blocksize))
378 return GSS_S_DEFECTIVE_TOKEN;
380 return GSS_S_COMPLETE;
384 * We can shift data by up to LOCAL_BUF_LEN bytes in a pass. If we need
385 * to do more than that, we shift repeatedly. Kevin Coffman reports
386 * seeing 28 bytes as the value used by Microsoft clients and servers
387 * with AES, so this constant is chosen to allow handling 28 in one pass
388 * without using too much stack space.
390 * If that proves to a problem perhaps we could use a more clever
393 #define LOCAL_BUF_LEN 32u
395 static void rotate_buf_a_little(struct xdr_buf *buf, unsigned int shift)
397 char head[LOCAL_BUF_LEN];
398 char tmp[LOCAL_BUF_LEN];
399 unsigned int this_len, i;
401 BUG_ON(shift > LOCAL_BUF_LEN);
403 read_bytes_from_xdr_buf(buf, 0, head, shift);
404 for (i = 0; i + shift < buf->len; i += LOCAL_BUF_LEN) {
405 this_len = min(LOCAL_BUF_LEN, buf->len - (i + shift));
406 read_bytes_from_xdr_buf(buf, i+shift, tmp, this_len);
407 write_bytes_to_xdr_buf(buf, i, tmp, this_len);
409 write_bytes_to_xdr_buf(buf, buf->len - shift, head, shift);
412 static void _rotate_left(struct xdr_buf *buf, unsigned int shift)
418 while (shifted < shift) {
419 this_shift = min(shift - shifted, LOCAL_BUF_LEN);
420 rotate_buf_a_little(buf, this_shift);
421 shifted += this_shift;
425 static void rotate_left(u32 base, struct xdr_buf *buf, unsigned int shift)
427 struct xdr_buf subbuf;
429 xdr_buf_subsegment(buf, &subbuf, base, buf->len - base);
430 _rotate_left(&subbuf, shift);
434 gss_wrap_kerberos_v2(struct krb5_ctx *kctx, u32 offset,
435 struct xdr_buf *buf, struct page **pages)
441 __be16 *be16ptr, ec = 0;
445 dprintk("RPC: %s\n", __func__);
447 if (kctx->gk5e->encrypt_v2 == NULL)
448 return GSS_S_FAILURE;
450 /* make room for gss token header */
451 if (xdr_extend_head(buf, offset, GSS_KRB5_TOK_HDR_LEN))
452 return GSS_S_FAILURE;
454 /* construct gss token header */
455 ptr = plainhdr = buf->head[0].iov_base + offset;
456 *ptr++ = (unsigned char) ((KG2_TOK_WRAP>>8) & 0xff);
457 *ptr++ = (unsigned char) (KG2_TOK_WRAP & 0xff);
459 if ((kctx->flags & KRB5_CTX_FLAG_INITIATOR) == 0)
460 flags |= KG2_TOKEN_FLAG_SENTBYACCEPTOR;
461 if ((kctx->flags & KRB5_CTX_FLAG_ACCEPTOR_SUBKEY) != 0)
462 flags |= KG2_TOKEN_FLAG_ACCEPTORSUBKEY;
463 /* We always do confidentiality in wrap tokens */
464 flags |= KG2_TOKEN_FLAG_SEALED;
468 be16ptr = (__be16 *)ptr;
470 blocksize = crypto_blkcipher_blocksize(kctx->acceptor_enc);
471 *be16ptr++ = cpu_to_be16(ec);
472 /* "inner" token header always uses 0 for RRC */
473 *be16ptr++ = cpu_to_be16(0);
475 be64ptr = (__be64 *)be16ptr;
476 spin_lock(&krb5_seq_lock);
477 *be64ptr = cpu_to_be64(kctx->seq_send64++);
478 spin_unlock(&krb5_seq_lock);
480 err = (*kctx->gk5e->encrypt_v2)(kctx, offset, buf, ec, pages);
485 return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
489 gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf)
497 u32 headskip, tailskip;
498 u8 decrypted_hdr[GSS_KRB5_TOK_HDR_LEN];
499 unsigned int movelen;
502 dprintk("RPC: %s\n", __func__);
504 if (kctx->gk5e->decrypt_v2 == NULL)
505 return GSS_S_FAILURE;
507 ptr = buf->head[0].iov_base + offset;
509 if (be16_to_cpu(*((__be16 *)ptr)) != KG2_TOK_WRAP)
510 return GSS_S_DEFECTIVE_TOKEN;
513 if ((!kctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) ||
514 (kctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)))
515 return GSS_S_BAD_SIG;
517 if ((flags & KG2_TOKEN_FLAG_SEALED) == 0) {
518 dprintk("%s: token missing expected sealed flag\n", __func__);
519 return GSS_S_DEFECTIVE_TOKEN;
523 return GSS_S_DEFECTIVE_TOKEN;
525 ec = be16_to_cpup((__be16 *)(ptr + 4));
526 rrc = be16_to_cpup((__be16 *)(ptr + 6));
528 seqnum = be64_to_cpup((__be64 *)(ptr + 8));
531 rotate_left(offset + 16, buf, rrc);
533 err = (*kctx->gk5e->decrypt_v2)(kctx, offset, buf,
534 &headskip, &tailskip);
536 return GSS_S_FAILURE;
539 * Retrieve the decrypted gss token header and verify
540 * it against the original
542 err = read_bytes_from_xdr_buf(buf,
543 buf->len - GSS_KRB5_TOK_HDR_LEN - tailskip,
544 decrypted_hdr, GSS_KRB5_TOK_HDR_LEN);
546 dprintk("%s: error %u getting decrypted_hdr\n", __func__, err);
547 return GSS_S_FAILURE;
549 if (memcmp(ptr, decrypted_hdr, 6)
550 || memcmp(ptr + 8, decrypted_hdr + 8, 8)) {
551 dprintk("%s: token hdr, plaintext hdr mismatch!\n", __func__);
552 return GSS_S_FAILURE;
555 /* do sequencing checks */
557 /* it got through unscathed. Make sure the context is unexpired */
559 if (now > kctx->endtime)
560 return GSS_S_CONTEXT_EXPIRED;
563 * Move the head data back to the right position in xdr_buf.
564 * We ignore any "ec" data since it might be in the head or
565 * the tail, and we really don't need to deal with it.
566 * Note that buf->head[0].iov_len may indicate the available
567 * head buffer space rather than that actually occupied.
569 movelen = min_t(unsigned int, buf->head[0].iov_len, buf->len);
570 movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip;
571 BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen >
572 buf->head[0].iov_len);
573 memmove(ptr, ptr + GSS_KRB5_TOK_HDR_LEN + headskip, movelen);
574 buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip;
575 buf->len -= GSS_KRB5_TOK_HDR_LEN + headskip;
577 /* Trim off the checksum blob */
578 xdr_buf_trim(buf, GSS_KRB5_TOK_HDR_LEN + tailskip);
579 return GSS_S_COMPLETE;
583 gss_wrap_kerberos(struct gss_ctx *gctx, int offset,
584 struct xdr_buf *buf, struct page **pages)
586 struct krb5_ctx *kctx = gctx->internal_ctx_id;
588 switch (kctx->enctype) {
591 case ENCTYPE_DES_CBC_RAW:
592 case ENCTYPE_DES3_CBC_RAW:
593 case ENCTYPE_ARCFOUR_HMAC:
594 return gss_wrap_kerberos_v1(kctx, offset, buf, pages);
595 case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
596 case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
597 return gss_wrap_kerberos_v2(kctx, offset, buf, pages);
602 gss_unwrap_kerberos(struct gss_ctx *gctx, int offset, struct xdr_buf *buf)
604 struct krb5_ctx *kctx = gctx->internal_ctx_id;
606 switch (kctx->enctype) {
609 case ENCTYPE_DES_CBC_RAW:
610 case ENCTYPE_DES3_CBC_RAW:
611 case ENCTYPE_ARCFOUR_HMAC:
612 return gss_unwrap_kerberos_v1(kctx, offset, buf);
613 case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
614 case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
615 return gss_unwrap_kerberos_v2(kctx, offset, buf);