gss_krb5: Add support for rc4-hmac encryption
Add necessary changes to add kernel support for the rc4-hmac Kerberos encryption type used by Microsoft and described in rfc4757. Signed-off-by: Kevin Coffman <kwc@citi.umich.edu> Signed-off-by: Steve Dickson <steved@redhat.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Kevin Coffman
committed by
Trond Myklebust
Trond Myklebust
parent
5af46547ec
commit
fffdaef2eb
@@ -124,6 +124,114 @@ checksummer(struct scatterlist *sg, void *data)
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return crypto_hash_update(desc, sg, sg->length);
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}
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static int
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arcfour_hmac_md5_usage_to_salt(unsigned int usage, u8 salt[4])
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{
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unsigned int ms_usage;
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switch (usage) {
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case KG_USAGE_SIGN:
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ms_usage = 15;
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break;
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case KG_USAGE_SEAL:
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ms_usage = 13;
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break;
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default:
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return EINVAL;;
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}
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salt[0] = (ms_usage >> 0) & 0xff;
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salt[1] = (ms_usage >> 8) & 0xff;
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salt[2] = (ms_usage >> 16) & 0xff;
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salt[3] = (ms_usage >> 24) & 0xff;
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return 0;
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}
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static u32
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make_checksum_hmac_md5(struct krb5_ctx *kctx, char *header, int hdrlen,
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struct xdr_buf *body, int body_offset, u8 *cksumkey,
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unsigned int usage, struct xdr_netobj *cksumout)
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{
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struct hash_desc desc;
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struct scatterlist sg[1];
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int err;
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u8 checksumdata[GSS_KRB5_MAX_CKSUM_LEN];
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u8 rc4salt[4];
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struct crypto_hash *md5;
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struct crypto_hash *hmac_md5;
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if (cksumkey == NULL)
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return GSS_S_FAILURE;
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if (cksumout->len < kctx->gk5e->cksumlength) {
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dprintk("%s: checksum buffer length, %u, too small for %s\n",
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__func__, cksumout->len, kctx->gk5e->name);
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return GSS_S_FAILURE;
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}
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if (arcfour_hmac_md5_usage_to_salt(usage, rc4salt)) {
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dprintk("%s: invalid usage value %u\n", __func__, usage);
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return GSS_S_FAILURE;
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}
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md5 = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
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if (IS_ERR(md5))
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return GSS_S_FAILURE;
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hmac_md5 = crypto_alloc_hash(kctx->gk5e->cksum_name, 0,
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CRYPTO_ALG_ASYNC);
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if (IS_ERR(hmac_md5)) {
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crypto_free_hash(md5);
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return GSS_S_FAILURE;
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}
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desc.tfm = md5;
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desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
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err = crypto_hash_init(&desc);
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if (err)
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goto out;
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sg_init_one(sg, rc4salt, 4);
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err = crypto_hash_update(&desc, sg, 4);
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if (err)
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goto out;
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sg_init_one(sg, header, hdrlen);
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err = crypto_hash_update(&desc, sg, hdrlen);
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if (err)
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goto out;
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err = xdr_process_buf(body, body_offset, body->len - body_offset,
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checksummer, &desc);
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if (err)
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goto out;
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err = crypto_hash_final(&desc, checksumdata);
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if (err)
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goto out;
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desc.tfm = hmac_md5;
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desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
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err = crypto_hash_init(&desc);
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if (err)
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goto out;
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err = crypto_hash_setkey(hmac_md5, cksumkey, kctx->gk5e->keylength);
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if (err)
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goto out;
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sg_init_one(sg, checksumdata, crypto_hash_digestsize(md5));
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err = crypto_hash_digest(&desc, sg, crypto_hash_digestsize(md5),
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checksumdata);
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if (err)
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goto out;
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memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
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cksumout->len = kctx->gk5e->cksumlength;
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out:
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crypto_free_hash(md5);
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crypto_free_hash(hmac_md5);
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return err ? GSS_S_FAILURE : 0;
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}
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/*
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* checksum the plaintext data and hdrlen bytes of the token header
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* The checksum is performed over the first 8 bytes of the
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@@ -140,6 +248,11 @@ make_checksum(struct krb5_ctx *kctx, char *header, int hdrlen,
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u8 checksumdata[GSS_KRB5_MAX_CKSUM_LEN];
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unsigned int checksumlen;
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if (kctx->gk5e->ctype == CKSUMTYPE_HMAC_MD5_ARCFOUR)
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return make_checksum_hmac_md5(kctx, header, hdrlen,
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body, body_offset,
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cksumkey, usage, cksumout);
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if (cksumout->len < kctx->gk5e->cksumlength) {
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dprintk("%s: checksum buffer length, %u, too small for %s\n",
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__func__, cksumout->len, kctx->gk5e->name);
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@@ -733,3 +846,145 @@ out_err:
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ret = GSS_S_FAILURE;
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return ret;
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}
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/*
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* Compute Kseq given the initial session key and the checksum.
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* Set the key of the given cipher.
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*/
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int
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krb5_rc4_setup_seq_key(struct krb5_ctx *kctx, struct crypto_blkcipher *cipher,
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unsigned char *cksum)
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{
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struct crypto_hash *hmac;
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struct hash_desc desc;
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struct scatterlist sg[1];
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u8 Kseq[GSS_KRB5_MAX_KEYLEN];
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u32 zeroconstant = 0;
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int err;
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dprintk("%s: entered\n", __func__);
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hmac = crypto_alloc_hash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
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if (IS_ERR(hmac)) {
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dprintk("%s: error %ld, allocating hash '%s'\n",
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__func__, PTR_ERR(hmac), kctx->gk5e->cksum_name);
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return PTR_ERR(hmac);
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}
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desc.tfm = hmac;
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desc.flags = 0;
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err = crypto_hash_init(&desc);
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if (err)
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goto out_err;
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/* Compute intermediate Kseq from session key */
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err = crypto_hash_setkey(hmac, kctx->Ksess, kctx->gk5e->keylength);
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if (err)
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goto out_err;
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sg_init_table(sg, 1);
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sg_set_buf(sg, &zeroconstant, 4);
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err = crypto_hash_digest(&desc, sg, 4, Kseq);
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if (err)
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goto out_err;
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/* Compute final Kseq from the checksum and intermediate Kseq */
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err = crypto_hash_setkey(hmac, Kseq, kctx->gk5e->keylength);
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if (err)
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goto out_err;
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sg_set_buf(sg, cksum, 8);
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err = crypto_hash_digest(&desc, sg, 8, Kseq);
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if (err)
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goto out_err;
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err = crypto_blkcipher_setkey(cipher, Kseq, kctx->gk5e->keylength);
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if (err)
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goto out_err;
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err = 0;
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out_err:
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crypto_free_hash(hmac);
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dprintk("%s: returning %d\n", __func__, err);
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return err;
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}
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/*
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* Compute Kcrypt given the initial session key and the plaintext seqnum.
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* Set the key of cipher kctx->enc.
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*/
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int
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krb5_rc4_setup_enc_key(struct krb5_ctx *kctx, struct crypto_blkcipher *cipher,
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s32 seqnum)
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{
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struct crypto_hash *hmac;
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struct hash_desc desc;
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struct scatterlist sg[1];
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u8 Kcrypt[GSS_KRB5_MAX_KEYLEN];
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u8 zeroconstant[4] = {0};
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u8 seqnumarray[4];
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int err, i;
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dprintk("%s: entered, seqnum %u\n", __func__, seqnum);
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hmac = crypto_alloc_hash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
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if (IS_ERR(hmac)) {
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dprintk("%s: error %ld, allocating hash '%s'\n",
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__func__, PTR_ERR(hmac), kctx->gk5e->cksum_name);
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return PTR_ERR(hmac);
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}
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desc.tfm = hmac;
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desc.flags = 0;
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err = crypto_hash_init(&desc);
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if (err)
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goto out_err;
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/* Compute intermediate Kcrypt from session key */
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for (i = 0; i < kctx->gk5e->keylength; i++)
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Kcrypt[i] = kctx->Ksess[i] ^ 0xf0;
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err = crypto_hash_setkey(hmac, Kcrypt, kctx->gk5e->keylength);
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if (err)
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goto out_err;
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sg_init_table(sg, 1);
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sg_set_buf(sg, zeroconstant, 4);
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err = crypto_hash_digest(&desc, sg, 4, Kcrypt);
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if (err)
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goto out_err;
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/* Compute final Kcrypt from the seqnum and intermediate Kcrypt */
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err = crypto_hash_setkey(hmac, Kcrypt, kctx->gk5e->keylength);
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if (err)
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goto out_err;
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seqnumarray[0] = (unsigned char) ((seqnum >> 24) & 0xff);
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seqnumarray[1] = (unsigned char) ((seqnum >> 16) & 0xff);
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seqnumarray[2] = (unsigned char) ((seqnum >> 8) & 0xff);
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seqnumarray[3] = (unsigned char) ((seqnum >> 0) & 0xff);
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sg_set_buf(sg, seqnumarray, 4);
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err = crypto_hash_digest(&desc, sg, 4, Kcrypt);
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if (err)
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goto out_err;
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err = crypto_blkcipher_setkey(cipher, Kcrypt, kctx->gk5e->keylength);
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if (err)
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goto out_err;
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err = 0;
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out_err:
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crypto_free_hash(hmac);
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dprintk("%s: returning %d\n", __func__, err);
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return err;
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}
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