diff options
Diffstat (limited to 'net/sunrpc/auth_gss/gss_krb5_crypto.c')
| -rw-r--r-- | net/sunrpc/auth_gss/gss_krb5_crypto.c | 810 |
1 files changed, 810 insertions, 0 deletions
diff --git a/net/sunrpc/auth_gss/gss_krb5_crypto.c b/net/sunrpc/auth_gss/gss_krb5_crypto.c new file mode 100644 index 000000000..3ea58175e --- /dev/null +++ b/net/sunrpc/auth_gss/gss_krb5_crypto.c @@ -0,0 +1,810 @@ +/* + * linux/net/sunrpc/gss_krb5_crypto.c + * + * Copyright (c) 2000-2008 The Regents of the University of Michigan. + * All rights reserved. + * + * Andy Adamson <andros@umich.edu> + * Bruce Fields <bfields@umich.edu> + */ + +/* + * Copyright (C) 1998 by the FundsXpress, INC. + * + * All rights reserved. + * + * Export of this software from the United States of America may require + * a specific license from the United States Government. It is the + * responsibility of any person or organization contemplating export to + * obtain such a license before exporting. + * + * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and + * distribute this software and its documentation for any purpose and + * without fee is hereby granted, provided that the above copyright + * notice appear in all copies and that both that copyright notice and + * this permission notice appear in supporting documentation, and that + * the name of FundsXpress. not be used in advertising or publicity pertaining + * to distribution of the software without specific, written prior + * permission. FundsXpress makes no representations about the suitability of + * this software for any purpose. It is provided "as is" without express + * or implied warranty. + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED + * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. + */ + +#include <crypto/algapi.h> +#include <crypto/hash.h> +#include <crypto/skcipher.h> +#include <linux/err.h> +#include <linux/types.h> +#include <linux/mm.h> +#include <linux/scatterlist.h> +#include <linux/highmem.h> +#include <linux/pagemap.h> +#include <linux/random.h> +#include <linux/sunrpc/gss_krb5.h> +#include <linux/sunrpc/xdr.h> + +#if IS_ENABLED(CONFIG_SUNRPC_DEBUG) +# define RPCDBG_FACILITY RPCDBG_AUTH +#endif + +u32 +krb5_encrypt( + struct crypto_sync_skcipher *tfm, + void * iv, + void * in, + void * out, + int length) +{ + u32 ret = -EINVAL; + struct scatterlist sg[1]; + u8 local_iv[GSS_KRB5_MAX_BLOCKSIZE] = {0}; + SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm); + + if (length % crypto_sync_skcipher_blocksize(tfm) != 0) + goto out; + + if (crypto_sync_skcipher_ivsize(tfm) > GSS_KRB5_MAX_BLOCKSIZE) { + dprintk("RPC: gss_k5encrypt: tfm iv size too large %d\n", + crypto_sync_skcipher_ivsize(tfm)); + goto out; + } + + if (iv) + memcpy(local_iv, iv, crypto_sync_skcipher_ivsize(tfm)); + + memcpy(out, in, length); + sg_init_one(sg, out, length); + + skcipher_request_set_sync_tfm(req, tfm); + skcipher_request_set_callback(req, 0, NULL, NULL); + skcipher_request_set_crypt(req, sg, sg, length, local_iv); + + ret = crypto_skcipher_encrypt(req); + skcipher_request_zero(req); +out: + dprintk("RPC: krb5_encrypt returns %d\n", ret); + return ret; +} + +u32 +krb5_decrypt( + struct crypto_sync_skcipher *tfm, + void * iv, + void * in, + void * out, + int length) +{ + u32 ret = -EINVAL; + struct scatterlist sg[1]; + u8 local_iv[GSS_KRB5_MAX_BLOCKSIZE] = {0}; + SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm); + + if (length % crypto_sync_skcipher_blocksize(tfm) != 0) + goto out; + + if (crypto_sync_skcipher_ivsize(tfm) > GSS_KRB5_MAX_BLOCKSIZE) { + dprintk("RPC: gss_k5decrypt: tfm iv size too large %d\n", + crypto_sync_skcipher_ivsize(tfm)); + goto out; + } + if (iv) + memcpy(local_iv, iv, crypto_sync_skcipher_ivsize(tfm)); + + memcpy(out, in, length); + sg_init_one(sg, out, length); + + skcipher_request_set_sync_tfm(req, tfm); + skcipher_request_set_callback(req, 0, NULL, NULL); + skcipher_request_set_crypt(req, sg, sg, length, local_iv); + + ret = crypto_skcipher_decrypt(req); + skcipher_request_zero(req); +out: + dprintk("RPC: gss_k5decrypt returns %d\n",ret); + return ret; +} + +static int +checksummer(struct scatterlist *sg, void *data) +{ + struct ahash_request *req = data; + + ahash_request_set_crypt(req, sg, NULL, sg->length); + + return crypto_ahash_update(req); +} + +/* + * checksum the plaintext data and hdrlen bytes of the token header + * The checksum is performed over the first 8 bytes of the + * gss token header and then over the data body + */ +u32 +make_checksum(struct krb5_ctx *kctx, char *header, int hdrlen, + struct xdr_buf *body, int body_offset, u8 *cksumkey, + unsigned int usage, struct xdr_netobj *cksumout) +{ + struct crypto_ahash *tfm; + struct ahash_request *req; + struct scatterlist sg[1]; + int err = -1; + u8 *checksumdata; + unsigned int checksumlen; + + if (cksumout->len < kctx->gk5e->cksumlength) { + dprintk("%s: checksum buffer length, %u, too small for %s\n", + __func__, cksumout->len, kctx->gk5e->name); + return GSS_S_FAILURE; + } + + checksumdata = kmalloc(GSS_KRB5_MAX_CKSUM_LEN, GFP_KERNEL); + if (checksumdata == NULL) + return GSS_S_FAILURE; + + tfm = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC); + if (IS_ERR(tfm)) + goto out_free_cksum; + + req = ahash_request_alloc(tfm, GFP_KERNEL); + if (!req) + goto out_free_ahash; + + ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL); + + checksumlen = crypto_ahash_digestsize(tfm); + + if (cksumkey != NULL) { + err = crypto_ahash_setkey(tfm, cksumkey, + kctx->gk5e->keylength); + if (err) + goto out; + } + + err = crypto_ahash_init(req); + if (err) + goto out; + sg_init_one(sg, header, hdrlen); + ahash_request_set_crypt(req, sg, NULL, hdrlen); + err = crypto_ahash_update(req); + if (err) + goto out; + err = xdr_process_buf(body, body_offset, body->len - body_offset, + checksummer, req); + if (err) + goto out; + ahash_request_set_crypt(req, NULL, checksumdata, 0); + err = crypto_ahash_final(req); + if (err) + goto out; + + switch (kctx->gk5e->ctype) { + case CKSUMTYPE_RSA_MD5: + err = kctx->gk5e->encrypt(kctx->seq, NULL, checksumdata, + checksumdata, checksumlen); + if (err) + goto out; + memcpy(cksumout->data, + checksumdata + checksumlen - kctx->gk5e->cksumlength, + kctx->gk5e->cksumlength); + break; + case CKSUMTYPE_HMAC_SHA1_DES3: + memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength); + break; + default: + BUG(); + break; + } + cksumout->len = kctx->gk5e->cksumlength; +out: + ahash_request_free(req); +out_free_ahash: + crypto_free_ahash(tfm); +out_free_cksum: + kfree(checksumdata); + return err ? GSS_S_FAILURE : 0; +} + +/* + * checksum the plaintext data and hdrlen bytes of the token header + * Per rfc4121, sec. 4.2.4, the checksum is performed over the data + * body then over the first 16 octets of the MIC token + * Inclusion of the header data in the calculation of the + * checksum is optional. + */ +u32 +make_checksum_v2(struct krb5_ctx *kctx, char *header, int hdrlen, + struct xdr_buf *body, int body_offset, u8 *cksumkey, + unsigned int usage, struct xdr_netobj *cksumout) +{ + struct crypto_ahash *tfm; + struct ahash_request *req; + struct scatterlist sg[1]; + int err = -1; + u8 *checksumdata; + + if (kctx->gk5e->keyed_cksum == 0) { + dprintk("%s: expected keyed hash for %s\n", + __func__, kctx->gk5e->name); + return GSS_S_FAILURE; + } + if (cksumkey == NULL) { + dprintk("%s: no key supplied for %s\n", + __func__, kctx->gk5e->name); + return GSS_S_FAILURE; + } + + checksumdata = kmalloc(GSS_KRB5_MAX_CKSUM_LEN, GFP_KERNEL); + if (!checksumdata) + return GSS_S_FAILURE; + + tfm = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC); + if (IS_ERR(tfm)) + goto out_free_cksum; + + req = ahash_request_alloc(tfm, GFP_KERNEL); + if (!req) + goto out_free_ahash; + + ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL); + + err = crypto_ahash_setkey(tfm, cksumkey, kctx->gk5e->keylength); + if (err) + goto out; + + err = crypto_ahash_init(req); + if (err) + goto out; + err = xdr_process_buf(body, body_offset, body->len - body_offset, + checksummer, req); + if (err) + goto out; + if (header != NULL) { + sg_init_one(sg, header, hdrlen); + ahash_request_set_crypt(req, sg, NULL, hdrlen); + err = crypto_ahash_update(req); + if (err) + goto out; + } + ahash_request_set_crypt(req, NULL, checksumdata, 0); + err = crypto_ahash_final(req); + if (err) + goto out; + + cksumout->len = kctx->gk5e->cksumlength; + + switch (kctx->gk5e->ctype) { + case CKSUMTYPE_HMAC_SHA1_96_AES128: + case CKSUMTYPE_HMAC_SHA1_96_AES256: + /* note that this truncates the hash */ + memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength); + break; + default: + BUG(); + break; + } +out: + ahash_request_free(req); +out_free_ahash: + crypto_free_ahash(tfm); +out_free_cksum: + kfree(checksumdata); + return err ? GSS_S_FAILURE : 0; +} + +struct encryptor_desc { + u8 iv[GSS_KRB5_MAX_BLOCKSIZE]; + struct skcipher_request *req; + int pos; + struct xdr_buf *outbuf; + struct page **pages; + struct scatterlist infrags[4]; + struct scatterlist outfrags[4]; + int fragno; + int fraglen; +}; + +static int +encryptor(struct scatterlist *sg, void *data) +{ + struct encryptor_desc *desc = data; + struct xdr_buf *outbuf = desc->outbuf; + struct crypto_sync_skcipher *tfm = + crypto_sync_skcipher_reqtfm(desc->req); + struct page *in_page; + int thislen = desc->fraglen + sg->length; + int fraglen, ret; + int page_pos; + + /* Worst case is 4 fragments: head, end of page 1, start + * of page 2, tail. Anything more is a bug. */ + BUG_ON(desc->fragno > 3); + + page_pos = desc->pos - outbuf->head[0].iov_len; + if (page_pos >= 0 && page_pos < outbuf->page_len) { + /* pages are not in place: */ + int i = (page_pos + outbuf->page_base) >> PAGE_SHIFT; + in_page = desc->pages[i]; + } else { + in_page = sg_page(sg); + } + sg_set_page(&desc->infrags[desc->fragno], in_page, sg->length, + sg->offset); + sg_set_page(&desc->outfrags[desc->fragno], sg_page(sg), sg->length, + sg->offset); + desc->fragno++; + desc->fraglen += sg->length; + desc->pos += sg->length; + + fraglen = thislen & (crypto_sync_skcipher_blocksize(tfm) - 1); + thislen -= fraglen; + + if (thislen == 0) + return 0; + + sg_mark_end(&desc->infrags[desc->fragno - 1]); + sg_mark_end(&desc->outfrags[desc->fragno - 1]); + + skcipher_request_set_crypt(desc->req, desc->infrags, desc->outfrags, + thislen, desc->iv); + + ret = crypto_skcipher_encrypt(desc->req); + if (ret) + return ret; + + sg_init_table(desc->infrags, 4); + sg_init_table(desc->outfrags, 4); + + if (fraglen) { + sg_set_page(&desc->outfrags[0], sg_page(sg), fraglen, + sg->offset + sg->length - fraglen); + desc->infrags[0] = desc->outfrags[0]; + sg_assign_page(&desc->infrags[0], in_page); + desc->fragno = 1; + desc->fraglen = fraglen; + } else { + desc->fragno = 0; + desc->fraglen = 0; + } + return 0; +} + +int +gss_encrypt_xdr_buf(struct crypto_sync_skcipher *tfm, struct xdr_buf *buf, + int offset, struct page **pages) +{ + int ret; + struct encryptor_desc desc; + SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm); + + BUG_ON((buf->len - offset) % crypto_sync_skcipher_blocksize(tfm) != 0); + + skcipher_request_set_sync_tfm(req, tfm); + skcipher_request_set_callback(req, 0, NULL, NULL); + + memset(desc.iv, 0, sizeof(desc.iv)); + desc.req = req; + desc.pos = offset; + desc.outbuf = buf; + desc.pages = pages; + desc.fragno = 0; + desc.fraglen = 0; + + sg_init_table(desc.infrags, 4); + sg_init_table(desc.outfrags, 4); + + ret = xdr_process_buf(buf, offset, buf->len - offset, encryptor, &desc); + skcipher_request_zero(req); + return ret; +} + +struct decryptor_desc { + u8 iv[GSS_KRB5_MAX_BLOCKSIZE]; + struct skcipher_request *req; + struct scatterlist frags[4]; + int fragno; + int fraglen; +}; + +static int +decryptor(struct scatterlist *sg, void *data) +{ + struct decryptor_desc *desc = data; + int thislen = desc->fraglen + sg->length; + struct crypto_sync_skcipher *tfm = + crypto_sync_skcipher_reqtfm(desc->req); + int fraglen, ret; + + /* Worst case is 4 fragments: head, end of page 1, start + * of page 2, tail. Anything more is a bug. */ + BUG_ON(desc->fragno > 3); + sg_set_page(&desc->frags[desc->fragno], sg_page(sg), sg->length, + sg->offset); + desc->fragno++; + desc->fraglen += sg->length; + + fraglen = thislen & (crypto_sync_skcipher_blocksize(tfm) - 1); + thislen -= fraglen; + + if (thislen == 0) + return 0; + + sg_mark_end(&desc->frags[desc->fragno - 1]); + + skcipher_request_set_crypt(desc->req, desc->frags, desc->frags, + thislen, desc->iv); + + ret = crypto_skcipher_decrypt(desc->req); + if (ret) + return ret; + + sg_init_table(desc->frags, 4); + + if (fraglen) { + sg_set_page(&desc->frags[0], sg_page(sg), fraglen, + sg->offset + sg->length - fraglen); + desc->fragno = 1; + desc->fraglen = fraglen; + } else { + desc->fragno = 0; + desc->fraglen = 0; + } + return 0; +} + +int +gss_decrypt_xdr_buf(struct crypto_sync_skcipher *tfm, struct xdr_buf *buf, + int offset) +{ + int ret; + struct decryptor_desc desc; + SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm); + + /* XXXJBF: */ + BUG_ON((buf->len - offset) % crypto_sync_skcipher_blocksize(tfm) != 0); + + skcipher_request_set_sync_tfm(req, tfm); + skcipher_request_set_callback(req, 0, NULL, NULL); + + memset(desc.iv, 0, sizeof(desc.iv)); + desc.req = req; + desc.fragno = 0; + desc.fraglen = 0; + + sg_init_table(desc.frags, 4); + + ret = xdr_process_buf(buf, offset, buf->len - offset, decryptor, &desc); + skcipher_request_zero(req); + return ret; +} + +/* + * This function makes the assumption that it was ultimately called + * from gss_wrap(). + * + * The client auth_gss code moves any existing tail data into a + * separate page before calling gss_wrap. + * The server svcauth_gss code ensures that both the head and the + * tail have slack space of RPC_MAX_AUTH_SIZE before calling gss_wrap. + * + * Even with that guarantee, this function may be called more than + * once in the processing of gss_wrap(). The best we can do is + * verify at compile-time (see GSS_KRB5_SLACK_CHECK) that the + * largest expected shift will fit within RPC_MAX_AUTH_SIZE. + * At run-time we can verify that a single invocation of this + * function doesn't attempt to use more the RPC_MAX_AUTH_SIZE. + */ + +int +xdr_extend_head(struct xdr_buf *buf, unsigned int base, unsigned int shiftlen) +{ + u8 *p; + + if (shiftlen == 0) + return 0; + + BUILD_BUG_ON(GSS_KRB5_MAX_SLACK_NEEDED > RPC_MAX_AUTH_SIZE); + BUG_ON(shiftlen > RPC_MAX_AUTH_SIZE); + + p = buf->head[0].iov_base + base; + + memmove(p + shiftlen, p, buf->head[0].iov_len - base); + + buf->head[0].iov_len += shiftlen; + buf->len += shiftlen; + + return 0; +} + +static u32 +gss_krb5_cts_crypt(struct crypto_sync_skcipher *cipher, struct xdr_buf *buf, + u32 offset, u8 *iv, struct page **pages, int encrypt) +{ + u32 ret; + struct scatterlist sg[1]; + SYNC_SKCIPHER_REQUEST_ON_STACK(req, cipher); + u8 *data; + struct page **save_pages; + u32 len = buf->len - offset; + + if (len > GSS_KRB5_MAX_BLOCKSIZE * 2) { + WARN_ON(0); + return -ENOMEM; + } + data = kmalloc(GSS_KRB5_MAX_BLOCKSIZE * 2, GFP_KERNEL); + if (!data) + return -ENOMEM; + + /* + * For encryption, we want to read from the cleartext + * page cache pages, and write the encrypted data to + * the supplied xdr_buf pages. + */ + save_pages = buf->pages; + if (encrypt) + buf->pages = pages; + + ret = read_bytes_from_xdr_buf(buf, offset, data, len); + buf->pages = save_pages; + if (ret) + goto out; + + sg_init_one(sg, data, len); + + skcipher_request_set_sync_tfm(req, cipher); + skcipher_request_set_callback(req, 0, NULL, NULL); + skcipher_request_set_crypt(req, sg, sg, len, iv); + + if (encrypt) + ret = crypto_skcipher_encrypt(req); + else + ret = crypto_skcipher_decrypt(req); + + skcipher_request_zero(req); + + if (ret) + goto out; + + ret = write_bytes_to_xdr_buf(buf, offset, data, len); + +out: + kfree(data); + return ret; +} + +u32 +gss_krb5_aes_encrypt(struct krb5_ctx *kctx, u32 offset, + struct xdr_buf *buf, struct page **pages) +{ + u32 err; + struct xdr_netobj hmac; + u8 *cksumkey; + u8 *ecptr; + struct crypto_sync_skcipher *cipher, *aux_cipher; + int blocksize; + struct page **save_pages; + int nblocks, nbytes; + struct encryptor_desc desc; + u32 cbcbytes; + unsigned int usage; + + if (kctx->initiate) { + cipher = kctx->initiator_enc; + aux_cipher = kctx->initiator_enc_aux; + cksumkey = kctx->initiator_integ; + usage = KG_USAGE_INITIATOR_SEAL; + } else { + cipher = kctx->acceptor_enc; + aux_cipher = kctx->acceptor_enc_aux; + cksumkey = kctx->acceptor_integ; + usage = KG_USAGE_ACCEPTOR_SEAL; + } + blocksize = crypto_sync_skcipher_blocksize(cipher); + + /* hide the gss token header and insert the confounder */ + offset += GSS_KRB5_TOK_HDR_LEN; + if (xdr_extend_head(buf, offset, kctx->gk5e->conflen)) + return GSS_S_FAILURE; + gss_krb5_make_confounder(buf->head[0].iov_base + offset, kctx->gk5e->conflen); + offset -= GSS_KRB5_TOK_HDR_LEN; + + if (buf->tail[0].iov_base != NULL) { + ecptr = buf->tail[0].iov_base + buf->tail[0].iov_len; + } else { + buf->tail[0].iov_base = buf->head[0].iov_base + + buf->head[0].iov_len; + buf->tail[0].iov_len = 0; + ecptr = buf->tail[0].iov_base; + } + + /* copy plaintext gss token header after filler (if any) */ + memcpy(ecptr, buf->head[0].iov_base + offset, GSS_KRB5_TOK_HDR_LEN); + buf->tail[0].iov_len += GSS_KRB5_TOK_HDR_LEN; + buf->len += GSS_KRB5_TOK_HDR_LEN; + + /* Do the HMAC */ + hmac.len = GSS_KRB5_MAX_CKSUM_LEN; + hmac.data = buf->tail[0].iov_base + buf->tail[0].iov_len; + + /* + * When we are called, pages points to the real page cache + * data -- which we can't go and encrypt! buf->pages points + * to scratch pages which we are going to send off to the + * client/server. Swap in the plaintext pages to calculate + * the hmac. + */ + save_pages = buf->pages; + buf->pages = pages; + + err = make_checksum_v2(kctx, NULL, 0, buf, + offset + GSS_KRB5_TOK_HDR_LEN, + cksumkey, usage, &hmac); + buf->pages = save_pages; + if (err) + return GSS_S_FAILURE; + + nbytes = buf->len - offset - GSS_KRB5_TOK_HDR_LEN; + nblocks = (nbytes + blocksize - 1) / blocksize; + cbcbytes = 0; + if (nblocks > 2) + cbcbytes = (nblocks - 2) * blocksize; + + memset(desc.iv, 0, sizeof(desc.iv)); + + if (cbcbytes) { + SYNC_SKCIPHER_REQUEST_ON_STACK(req, aux_cipher); + + desc.pos = offset + GSS_KRB5_TOK_HDR_LEN; + desc.fragno = 0; + desc.fraglen = 0; + desc.pages = pages; + desc.outbuf = buf; + desc.req = req; + + skcipher_request_set_sync_tfm(req, aux_cipher); + skcipher_request_set_callback(req, 0, NULL, NULL); + + sg_init_table(desc.infrags, 4); + sg_init_table(desc.outfrags, 4); + + err = xdr_process_buf(buf, offset + GSS_KRB5_TOK_HDR_LEN, + cbcbytes, encryptor, &desc); + skcipher_request_zero(req); + if (err) + goto out_err; + } + + /* Make sure IV carries forward from any CBC results. */ + err = gss_krb5_cts_crypt(cipher, buf, + offset + GSS_KRB5_TOK_HDR_LEN + cbcbytes, + desc.iv, pages, 1); + if (err) { + err = GSS_S_FAILURE; + goto out_err; + } + + /* Now update buf to account for HMAC */ + buf->tail[0].iov_len += kctx->gk5e->cksumlength; + buf->len += kctx->gk5e->cksumlength; + +out_err: + if (err) + err = GSS_S_FAILURE; + return err; +} + +u32 +gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, u32 len, + struct xdr_buf *buf, u32 *headskip, u32 *tailskip) +{ + struct xdr_buf subbuf; + u32 ret = 0; + u8 *cksum_key; + struct crypto_sync_skcipher *cipher, *aux_cipher; + struct xdr_netobj our_hmac_obj; + u8 our_hmac[GSS_KRB5_MAX_CKSUM_LEN]; + u8 pkt_hmac[GSS_KRB5_MAX_CKSUM_LEN]; + int nblocks, blocksize, cbcbytes; + struct decryptor_desc desc; + unsigned int usage; + + if (kctx->initiate) { + cipher = kctx->acceptor_enc; + aux_cipher = kctx->acceptor_enc_aux; + cksum_key = kctx->acceptor_integ; + usage = KG_USAGE_ACCEPTOR_SEAL; + } else { + cipher = kctx->initiator_enc; + aux_cipher = kctx->initiator_enc_aux; + cksum_key = kctx->initiator_integ; + usage = KG_USAGE_INITIATOR_SEAL; + } + blocksize = crypto_sync_skcipher_blocksize(cipher); + + + /* create a segment skipping the header and leaving out the checksum */ + xdr_buf_subsegment(buf, &subbuf, offset + GSS_KRB5_TOK_HDR_LEN, + (len - offset - GSS_KRB5_TOK_HDR_LEN - + kctx->gk5e->cksumlength)); + + nblocks = (subbuf.len + blocksize - 1) / blocksize; + + cbcbytes = 0; + if (nblocks > 2) + cbcbytes = (nblocks - 2) * blocksize; + + memset(desc.iv, 0, sizeof(desc.iv)); + + if (cbcbytes) { + SYNC_SKCIPHER_REQUEST_ON_STACK(req, aux_cipher); + + desc.fragno = 0; + desc.fraglen = 0; + desc.req = req; + + skcipher_request_set_sync_tfm(req, aux_cipher); + skcipher_request_set_callback(req, 0, NULL, NULL); + + sg_init_table(desc.frags, 4); + + ret = xdr_process_buf(&subbuf, 0, cbcbytes, decryptor, &desc); + skcipher_request_zero(req); + if (ret) + goto out_err; + } + + /* Make sure IV carries forward from any CBC results. */ + ret = gss_krb5_cts_crypt(cipher, &subbuf, cbcbytes, desc.iv, NULL, 0); + if (ret) + goto out_err; + + + /* Calculate our hmac over the plaintext data */ + our_hmac_obj.len = sizeof(our_hmac); + our_hmac_obj.data = our_hmac; + + ret = make_checksum_v2(kctx, NULL, 0, &subbuf, 0, + cksum_key, usage, &our_hmac_obj); + if (ret) + goto out_err; + + /* Get the packet's hmac value */ + ret = read_bytes_from_xdr_buf(buf, len - kctx->gk5e->cksumlength, + pkt_hmac, kctx->gk5e->cksumlength); + if (ret) + goto out_err; + + if (crypto_memneq(pkt_hmac, our_hmac, kctx->gk5e->cksumlength) != 0) { + ret = GSS_S_BAD_SIG; + goto out_err; + } + *headskip = kctx->gk5e->conflen; + *tailskip = kctx->gk5e->cksumlength; +out_err: + if (ret && ret != GSS_S_BAD_SIG) + ret = GSS_S_FAILURE; + return ret; +} |