gss_krb5: Use confounder length in wrap code

All encryption types use a confounder at the beginning of the
wrap token.  In all encryption types except arcfour-hmac, the
confounder is the same as the blocksize.  arcfour-hmac has a
blocksize of one, but uses an eight byte confounder.

Add an entry to the crypto framework definitions for the
confounder length and change the wrap/unwrap code to use
the confounder length rather than assuming it is always
the blocksize.
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>

include/linux/sunrpc/gss_krb5.h

@@ -64,6 +64,9 @@ struct gss_krb5_enctype {
 	const u16		signalg;	/* signing algorithm */
 	const u16		sealalg;	/* sealing algorithm */
 	const u32		blocksize;	/* encryption blocksize */
+	const u32		conflen;	/* confounder length
+						   (normally the same as
+						   the blocksize) */
 	const u32		cksumlength;	/* checksum length */
 	const u32		keyed_cksum;	/* is it a keyed cksum? */
 	const u32		keybytes;	/* raw key len, in bytes */

net/sunrpc/auth_gss/gss_krb5_crypto.c

@@ -554,9 +554,9 @@ gss_krb5_aes_encrypt(struct krb5_ctx *kctx, u32 offset,
 
 	/* hide the gss token header and insert the confounder */
 	offset += GSS_KRB5_TOK_HDR_LEN;
-	if (xdr_extend_head(buf, offset, blocksize))
+	if (xdr_extend_head(buf, offset, kctx->gk5e->conflen))
 		return GSS_S_FAILURE;
-	gss_krb5_make_confounder(buf->head[0].iov_base + offset, blocksize);
+	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) {
@@ -726,7 +726,7 @@ gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, struct xdr_buf *buf,
 		ret = GSS_S_BAD_SIG;
 		goto out_err;
 	}
-	*headskip = crypto_blkcipher_blocksize(cipher);
+	*headskip = kctx->gk5e->conflen;
 	*tailskip = kctx->gk5e->cksumlength;
 out_err:
 	if (ret && ret != GSS_S_BAD_SIG)

net/sunrpc/auth_gss/gss_krb5_mech.c

@@ -68,6 +68,7 @@ static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {
 	  .keybytes = 7,
 	  .keylength = 8,
 	  .blocksize = 8,
+	  .conflen = 8,
 	  .cksumlength = 8,
 	  .keyed_cksum = 0,
 	},
@@ -88,6 +89,7 @@ static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {
 	  .keybytes = 21,
 	  .keylength = 24,
 	  .blocksize = 8,
+	  .conflen = 8,
 	  .cksumlength = 20,
 	  .keyed_cksum = 1,
 	},
@@ -110,6 +112,7 @@ static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {
 	  .keybytes = 16,
 	  .keylength = 16,
 	  .blocksize = 16,
+	  .conflen = 16,
 	  .cksumlength = 12,
 	  .keyed_cksum = 1,
 	},
@@ -132,6 +135,7 @@ static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {
 	  .keybytes = 32,
 	  .keylength = 32,
 	  .blocksize = 16,
+	  .conflen = 16,
 	  .cksumlength = 12,
 	  .keyed_cksum = 1,
 	},

net/sunrpc/auth_gss/gss_krb5_wrap.c

@@ -168,6 +168,7 @@ gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset,
 	struct page		**tmp_pages;
 	u32			seq_send;
 	u8			*cksumkey;
+	u32			conflen = kctx->gk5e->conflen;
 
 	dprintk("RPC:       %s\n", __func__);
 
@@ -176,7 +177,7 @@ gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset,
 	blocksize = crypto_blkcipher_blocksize(kctx->enc);
 	gss_krb5_add_padding(buf, offset, blocksize);
 	BUG_ON((buf->len - offset) % blocksize);
-	plainlen = blocksize + buf->len - offset;
+	plainlen = conflen + buf->len - offset;
 
 	headlen = g_token_size(&kctx->mech_used,
 		GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength + plainlen) -
@@ -204,7 +205,7 @@ gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset,
 	memset(ptr + 4, 0xff, 4);
 	*(__be16 *)(ptr + 4) = cpu_to_le16(kctx->gk5e->sealalg);
 
-	gss_krb5_make_confounder(msg_start, blocksize);
+	gss_krb5_make_confounder(msg_start, conflen);
 
 	if (kctx->gk5e->keyed_cksum)
 		cksumkey = kctx->cksum;
@@ -214,7 +215,7 @@ gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset,
 	/* XXXJBF: UGH!: */
 	tmp_pages = buf->pages;
 	buf->pages = pages;
-	if (make_checksum(kctx, ptr, 8, buf, offset + headlen - blocksize,
+	if (make_checksum(kctx, ptr, 8, buf, offset + headlen - conflen,
 					cksumkey, KG_USAGE_SEAL, &md5cksum))
 		return GSS_S_FAILURE;
 	buf->pages = tmp_pages;
@@ -231,7 +232,7 @@ gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset,
 			       seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8)))
 		return GSS_S_FAILURE;
 
-	if (gss_encrypt_xdr_buf(kctx->enc, buf, offset + headlen - blocksize,
+	if (gss_encrypt_xdr_buf(kctx->enc, buf, offset + headlen - conflen,
 									pages))
 		return GSS_S_FAILURE;
 
@@ -254,6 +255,7 @@ gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf)
 	void			*data_start, *orig_start;
 	int			data_len;
 	int			blocksize;
+	u32			conflen = kctx->gk5e->conflen;
 	int			crypt_offset;
 	u8			*cksumkey;
 
@@ -327,7 +329,7 @@ gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf)
 
 	blocksize = crypto_blkcipher_blocksize(kctx->enc);
 	data_start = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) +
-					blocksize;
+					conflen;
 	orig_start = buf->head[0].iov_base + offset;
 	data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start;
 	memmove(orig_start, data_start, data_len);