diff options
Diffstat (limited to 'net/sunrpc/auth_gss/gss_krb5_crypto.c')
| -rw-r--r-- | net/sunrpc/auth_gss/gss_krb5_crypto.c | 697 |
1 files changed, 680 insertions, 17 deletions
diff --git a/net/sunrpc/auth_gss/gss_krb5_crypto.c b/net/sunrpc/auth_gss/gss_krb5_crypto.c index e9b636176687..75ee993ea057 100644 --- a/net/sunrpc/auth_gss/gss_krb5_crypto.c +++ b/net/sunrpc/auth_gss/gss_krb5_crypto.c @@ -1,7 +1,7 @@ /* * linux/net/sunrpc/gss_krb5_crypto.c * - * Copyright (c) 2000 The Regents of the University of Michigan. + * Copyright (c) 2000-2008 The Regents of the University of Michigan. * All rights reserved. * * Andy Adamson <andros@umich.edu> @@ -41,6 +41,7 @@ #include <linux/crypto.h> #include <linux/highmem.h> #include <linux/pagemap.h> +#include <linux/random.h> #include <linux/sunrpc/gss_krb5.h> #include <linux/sunrpc/xdr.h> @@ -58,13 +59,13 @@ krb5_encrypt( { u32 ret = -EINVAL; struct scatterlist sg[1]; - u8 local_iv[16] = {0}; + u8 local_iv[GSS_KRB5_MAX_BLOCKSIZE] = {0}; struct blkcipher_desc desc = { .tfm = tfm, .info = local_iv }; if (length % crypto_blkcipher_blocksize(tfm) != 0) goto out; - if (crypto_blkcipher_ivsize(tfm) > 16) { + if (crypto_blkcipher_ivsize(tfm) > GSS_KRB5_MAX_BLOCKSIZE) { dprintk("RPC: gss_k5encrypt: tfm iv size too large %d\n", crypto_blkcipher_ivsize(tfm)); goto out; @@ -92,13 +93,13 @@ krb5_decrypt( { u32 ret = -EINVAL; struct scatterlist sg[1]; - u8 local_iv[16] = {0}; + u8 local_iv[GSS_KRB5_MAX_BLOCKSIZE] = {0}; struct blkcipher_desc desc = { .tfm = tfm, .info = local_iv }; if (length % crypto_blkcipher_blocksize(tfm) != 0) goto out; - if (crypto_blkcipher_ivsize(tfm) > 16) { + if (crypto_blkcipher_ivsize(tfm) > GSS_KRB5_MAX_BLOCKSIZE) { dprintk("RPC: gss_k5decrypt: tfm iv size too large %d\n", crypto_blkcipher_ivsize(tfm)); goto out; @@ -123,21 +124,155 @@ checksummer(struct scatterlist *sg, void *data) return crypto_hash_update(desc, sg, sg->length); } -/* checksum the plaintext data and hdrlen bytes of the token header */ -s32 -make_checksum(char *cksumname, char *header, int hdrlen, struct xdr_buf *body, - int body_offset, struct xdr_netobj *cksum) +static int +arcfour_hmac_md5_usage_to_salt(unsigned int usage, u8 salt[4]) +{ + unsigned int ms_usage; + + switch (usage) { + case KG_USAGE_SIGN: + ms_usage = 15; + break; + case KG_USAGE_SEAL: + ms_usage = 13; + break; + default: + return EINVAL;; + } + salt[0] = (ms_usage >> 0) & 0xff; + salt[1] = (ms_usage >> 8) & 0xff; + salt[2] = (ms_usage >> 16) & 0xff; + salt[3] = (ms_usage >> 24) & 0xff; + + return 0; +} + +static u32 +make_checksum_hmac_md5(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 hash_desc desc; /* XXX add to ctx? */ + struct hash_desc desc; struct scatterlist sg[1]; int err; + u8 checksumdata[GSS_KRB5_MAX_CKSUM_LEN]; + u8 rc4salt[4]; + struct crypto_hash *md5; + struct crypto_hash *hmac_md5; + + if (cksumkey == NULL) + return GSS_S_FAILURE; + + 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; + } + + if (arcfour_hmac_md5_usage_to_salt(usage, rc4salt)) { + dprintk("%s: invalid usage value %u\n", __func__, usage); + return GSS_S_FAILURE; + } + + md5 = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC); + if (IS_ERR(md5)) + return GSS_S_FAILURE; + + hmac_md5 = crypto_alloc_hash(kctx->gk5e->cksum_name, 0, + CRYPTO_ALG_ASYNC); + if (IS_ERR(hmac_md5)) { + crypto_free_hash(md5); + return GSS_S_FAILURE; + } + + desc.tfm = md5; + desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP; + + err = crypto_hash_init(&desc); + if (err) + goto out; + sg_init_one(sg, rc4salt, 4); + err = crypto_hash_update(&desc, sg, 4); + if (err) + goto out; + + sg_init_one(sg, header, hdrlen); + err = crypto_hash_update(&desc, sg, hdrlen); + if (err) + goto out; + err = xdr_process_buf(body, body_offset, body->len - body_offset, + checksummer, &desc); + if (err) + goto out; + err = crypto_hash_final(&desc, checksumdata); + if (err) + goto out; + + desc.tfm = hmac_md5; + desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP; + + err = crypto_hash_init(&desc); + if (err) + goto out; + err = crypto_hash_setkey(hmac_md5, cksumkey, kctx->gk5e->keylength); + if (err) + goto out; + + sg_init_one(sg, checksumdata, crypto_hash_digestsize(md5)); + err = crypto_hash_digest(&desc, sg, crypto_hash_digestsize(md5), + checksumdata); + if (err) + goto out; + + memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength); + cksumout->len = kctx->gk5e->cksumlength; +out: + crypto_free_hash(md5); + crypto_free_hash(hmac_md5); + return err ? GSS_S_FAILURE : 0; +} + +/* + * 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 hash_desc desc; + struct scatterlist sg[1]; + int err; + u8 checksumdata[GSS_KRB5_MAX_CKSUM_LEN]; + unsigned int checksumlen; + + if (kctx->gk5e->ctype == CKSUMTYPE_HMAC_MD5_ARCFOUR) + return make_checksum_hmac_md5(kctx, header, hdrlen, + body, body_offset, + cksumkey, usage, cksumout); + + 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; + } - desc.tfm = crypto_alloc_hash(cksumname, 0, CRYPTO_ALG_ASYNC); + desc.tfm = crypto_alloc_hash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC); if (IS_ERR(desc.tfm)) return GSS_S_FAILURE; - cksum->len = crypto_hash_digestsize(desc.tfm); desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP; + checksumlen = crypto_hash_digestsize(desc.tfm); + + if (cksumkey != NULL) { + err = crypto_hash_setkey(desc.tfm, cksumkey, + kctx->gk5e->keylength); + if (err) + goto out; + } + err = crypto_hash_init(&desc); if (err) goto out; @@ -149,15 +284,109 @@ make_checksum(char *cksumname, char *header, int hdrlen, struct xdr_buf *body, checksummer, &desc); if (err) goto out; - err = crypto_hash_final(&desc, cksum->data); + err = crypto_hash_final(&desc, checksumdata); + 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: + crypto_free_hash(desc.tfm); + 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 hash_desc desc; + struct scatterlist sg[1]; + int err; + u8 checksumdata[GSS_KRB5_MAX_CKSUM_LEN]; + unsigned int checksumlen; + + 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; + } + + desc.tfm = crypto_alloc_hash(kctx->gk5e->cksum_name, 0, + CRYPTO_ALG_ASYNC); + if (IS_ERR(desc.tfm)) + return GSS_S_FAILURE; + checksumlen = crypto_hash_digestsize(desc.tfm); + desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP; + + err = crypto_hash_setkey(desc.tfm, cksumkey, kctx->gk5e->keylength); + if (err) + goto out; + + err = crypto_hash_init(&desc); + if (err) + goto out; + err = xdr_process_buf(body, body_offset, body->len - body_offset, + checksummer, &desc); + if (err) + goto out; + if (header != NULL) { + sg_init_one(sg, header, hdrlen); + err = crypto_hash_update(&desc, sg, hdrlen); + if (err) + goto out; + } + err = crypto_hash_final(&desc, checksumdata); + 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: crypto_free_hash(desc.tfm); return err ? GSS_S_FAILURE : 0; } struct encryptor_desc { - u8 iv[8]; /* XXX hard-coded blocksize */ + u8 iv[GSS_KRB5_MAX_BLOCKSIZE]; struct blkcipher_desc desc; int pos; struct xdr_buf *outbuf; @@ -198,7 +427,7 @@ encryptor(struct scatterlist *sg, void *data) desc->fraglen += sg->length; desc->pos += sg->length; - fraglen = thislen & 7; /* XXX hardcoded blocksize */ + fraglen = thislen & (crypto_blkcipher_blocksize(desc->desc.tfm) - 1); thislen -= fraglen; if (thislen == 0) @@ -256,7 +485,7 @@ gss_encrypt_xdr_buf(struct crypto_blkcipher *tfm, struct xdr_buf *buf, } struct decryptor_desc { - u8 iv[8]; /* XXX hard-coded blocksize */ + u8 iv[GSS_KRB5_MAX_BLOCKSIZE]; struct blkcipher_desc desc; struct scatterlist frags[4]; int fragno; @@ -278,7 +507,7 @@ decryptor(struct scatterlist *sg, void *data) desc->fragno++; desc->fraglen += sg->length; - fraglen = thislen & 7; /* XXX hardcoded blocksize */ + fraglen = thislen & (crypto_blkcipher_blocksize(desc->desc.tfm) - 1); thislen -= fraglen; if (thislen == 0) @@ -325,3 +554,437 @@ gss_decrypt_xdr_buf(struct crypto_blkcipher *tfm, struct xdr_buf *buf, return xdr_process_buf(buf, offset, buf->len - offset, decryptor, &desc); } + +/* + * 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_blkcipher *cipher, struct xdr_buf *buf, + u32 offset, u8 *iv, struct page **pages, int encrypt) +{ + u32 ret; + struct scatterlist sg[1]; + struct blkcipher_desc desc = { .tfm = cipher, .info = iv }; + u8 data[crypto_blkcipher_blocksize(cipher) * 2]; + struct page **save_pages; + u32 len = buf->len - offset; + + BUG_ON(len > crypto_blkcipher_blocksize(cipher) * 2); + + /* + * 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); + + if (encrypt) + ret = crypto_blkcipher_encrypt_iv(&desc, sg, sg, len); + else + ret = crypto_blkcipher_decrypt_iv(&desc, sg, sg, len); + + if (ret) + goto out; + + ret = write_bytes_to_xdr_buf(buf, offset, data, len); + +out: + return ret; +} + +u32 +gss_krb5_aes_encrypt(struct krb5_ctx *kctx, u32 offset, + struct xdr_buf *buf, int ec, struct page **pages) +{ + u32 err; + struct xdr_netobj hmac; + u8 *cksumkey; + u8 *ecptr; + struct crypto_blkcipher *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_blkcipher_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; + } + + memset(ecptr, 'X', ec); + buf->tail[0].iov_len += ec; + buf->len += ec; + + /* copy plaintext gss token header after filler (if any) */ + memcpy(ecptr + ec, 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) { + desc.pos = offset + GSS_KRB5_TOK_HDR_LEN; + desc.fragno = 0; + desc.fraglen = 0; + desc.pages = pages; + desc.outbuf = buf; + desc.desc.info = desc.iv; + desc.desc.flags = 0; + desc.desc.tfm = aux_cipher; + + 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); + 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, struct xdr_buf *buf, + u32 *headskip, u32 *tailskip) +{ + struct xdr_buf subbuf; + u32 ret = 0; + u8 *cksum_key; + struct crypto_blkcipher *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_blkcipher_blocksize(cipher); + + + /* create a segment skipping the header and leaving out the checksum */ + xdr_buf_subsegment(buf, &subbuf, offset + GSS_KRB5_TOK_HDR_LEN, + (buf->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) { + desc.fragno = 0; + desc.fraglen = 0; + desc.desc.info = desc.iv; + desc.desc.flags = 0; + desc.desc.tfm = aux_cipher; + + sg_init_table(desc.frags, 4); + + ret = xdr_process_buf(&subbuf, 0, cbcbytes, decryptor, &desc); + 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, buf->len - kctx->gk5e->cksumlength, + pkt_hmac, kctx->gk5e->cksumlength); + if (ret) + goto out_err; + + if (memcmp(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; +} + +/* + * Compute Kseq given the initial session key and the checksum. + * Set the key of the given cipher. + */ +int +krb5_rc4_setup_seq_key(struct krb5_ctx *kctx, struct crypto_blkcipher *cipher, + unsigned char *cksum) +{ + struct crypto_hash *hmac; + struct hash_desc desc; + struct scatterlist sg[1]; + u8 Kseq[GSS_KRB5_MAX_KEYLEN]; + u32 zeroconstant = 0; + int err; + + dprintk("%s: entered\n", __func__); + + hmac = crypto_alloc_hash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC); + if (IS_ERR(hmac)) { + dprintk("%s: error %ld, allocating hash '%s'\n", + __func__, PTR_ERR(hmac), kctx->gk5e->cksum_name); + return PTR_ERR(hmac); + } + + desc.tfm = hmac; + desc.flags = 0; + + err = crypto_hash_init(&desc); + if (err) + goto out_err; + + /* Compute intermediate Kseq from session key */ + err = crypto_hash_setkey(hmac, kctx->Ksess, kctx->gk5e->keylength); + if (err) + goto out_err; + + sg_init_table(sg, 1); + sg_set_buf(sg, &zeroconstant, 4); + + err = crypto_hash_digest(&desc, sg, 4, Kseq); + if (err) + goto out_err; + + /* Compute final Kseq from the checksum and intermediate Kseq */ + err = crypto_hash_setkey(hmac, Kseq, kctx->gk5e->keylength); + if (err) + goto out_err; + + sg_set_buf(sg, cksum, 8); + + err = crypto_hash_digest(&desc, sg, 8, Kseq); + if (err) + goto out_err; + + err = crypto_blkcipher_setkey(cipher, Kseq, kctx->gk5e->keylength); + if (err) + goto out_err; + + err = 0; + +out_err: + crypto_free_hash(hmac); + dprintk("%s: returning %d\n", __func__, err); + return err; +} + +/* + * Compute Kcrypt given the initial session key and the plaintext seqnum. + * Set the key of cipher kctx->enc. + */ +int +krb5_rc4_setup_enc_key(struct krb5_ctx *kctx, struct crypto_blkcipher *cipher, + s32 seqnum) +{ + struct crypto_hash *hmac; + struct hash_desc desc; + struct scatterlist sg[1]; + u8 Kcrypt[GSS_KRB5_MAX_KEYLEN]; + u8 zeroconstant[4] = {0}; + u8 seqnumarray[4]; + int err, i; + + dprintk("%s: entered, seqnum %u\n", __func__, seqnum); + + hmac = crypto_alloc_hash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC); + if (IS_ERR(hmac)) { + dprintk("%s: error %ld, allocating hash '%s'\n", + __func__, PTR_ERR(hmac), kctx->gk5e->cksum_name); + return PTR_ERR(hmac); + } + + desc.tfm = hmac; + desc.flags = 0; + + err = crypto_hash_init(&desc); + if (err) + goto out_err; + + /* Compute intermediate Kcrypt from session key */ + for (i = 0; i < kctx->gk5e->keylength; i++) + Kcrypt[i] = kctx->Ksess[i] ^ 0xf0; + + err = crypto_hash_setkey(hmac, Kcrypt, kctx->gk5e->keylength); + if (err) + goto out_err; + + sg_init_table(sg, 1); + sg_set_buf(sg, zeroconstant, 4); + + err = crypto_hash_digest(&desc, sg, 4, Kcrypt); + if (err) + goto out_err; + + /* Compute final Kcrypt from the seqnum and intermediate Kcrypt */ + err = crypto_hash_setkey(hmac, Kcrypt, kctx->gk5e->keylength); + if (err) + goto out_err; + + seqnumarray[0] = (unsigned char) ((seqnum >> 24) & 0xff); + seqnumarray[1] = (unsigned char) ((seqnum >> 16) & 0xff); + seqnumarray[2] = (unsigned char) ((seqnum >> 8) & 0xff); + seqnumarray[3] = (unsigned char) ((seqnum >> 0) & 0xff); + + sg_set_buf(sg, seqnumarray, 4); + + err = crypto_hash_digest(&desc, sg, 4, Kcrypt); + if (err) + goto out_err; + + err = crypto_blkcipher_setkey(cipher, Kcrypt, kctx->gk5e->keylength); + if (err) + goto out_err; + + err = 0; + +out_err: + crypto_free_hash(hmac); + dprintk("%s: returning %d\n", __func__, err); + return err; +} + |