[PATCH 27/28] gss_krb5: add confounder length to kerberos enctype framework

[Kevin Coffman]

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 at citi.umich.edu>
---

 include/linux/sunrpc/gss_krb5.h     |    3 +++
 net/sunrpc/auth_gss/gss_krb5_mech.c |    4 ++++
 net/sunrpc/auth_gss/gss_krb5_wrap.c |   12 +++++++-----
 3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/include/linux/sunrpc/gss_krb5.h b/include/linux/sunrpc/gss_krb5.h
index 57b3686..5378ac8 100644
--- a/include/linux/sunrpc/gss_krb5.h
+++ b/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 */
diff --git a/net/sunrpc/auth_gss/gss_krb5_mech.c b/net/sunrpc/auth_gss/gss_krb5_mech.c
index 34ead67..9df0458 100644
--- a/net/sunrpc/auth_gss/gss_krb5_mech.c
+++ b/net/sunrpc/auth_gss/gss_krb5_mech.c
@@ -66,6 +66,7 @@ static struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {
 	  .keybytes = 7,
 	  .keylength = 8,
 	  .blocksize = 8,
+	  .conflen = 8,
 	  .cksumlength = 8,
 	  .keyed_cksum = 0,
 	},
@@ -86,6 +87,7 @@ static struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {
 	  .keybytes = 21,
 	  .keylength = 24,
 	  .blocksize = 8,
+	  .conflen = 8,
 	  .cksumlength = 20,
 	  .keyed_cksum = 1,
 	},
@@ -108,6 +110,7 @@ static struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {
 	  .keybytes = 16,
 	  .keylength = 16,
 	  .blocksize = 16,
+	  .conflen = 16,
 	  .cksumlength = 12,
 	  .keyed_cksum = 1,
 	},
@@ -130,6 +133,7 @@ static struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {
 	  .keybytes = 32,
 	  .keylength = 32,
 	  .blocksize = 16,
+	  .conflen = 16,
 	  .cksumlength = 12,
 	  .keyed_cksum = 1,
 	},
diff --git a/net/sunrpc/auth_gss/gss_krb5_wrap.c b/net/sunrpc/auth_gss/gss_krb5_wrap.c
index 701df35..a1df8dd 100644
--- a/net/sunrpc/auth_gss/gss_krb5_wrap.c
+++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c
@@ -136,6 +136,7 @@ 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__);
 
@@ -144,7 +145,7 @@ 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(&krb5_oid,
 		16 + kctx->gk5e->cksumlength + plainlen) - (buf->len - offset);
@@ -173,7 +174,7 @@ gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset,
 	memset(krb5_hdr + 4, 0xff, 4);
 	*(__be16 *)(krb5_hdr + 4) = cpu_to_le16(kctx->gk5e->sealalg);
 
-	make_confounder(msg_start, blocksize);
+	make_confounder(msg_start, conflen);
 
 	if (kctx->gk5e->keyed_cksum)
 		cksumkey = kctx->cksum;
@@ -183,7 +184,7 @@ gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset,
 	/* XXXJBF: UGH!: */
 	tmp_pages = buf->pages;
 	buf->pages = pages;
-	if (make_checksum(kctx, krb5_hdr, 8, buf, offset + headlen - blocksize,
+	if (make_checksum(kctx, krb5_hdr, 8, buf, offset + headlen - conflen,
 					cksumkey, KG_USAGE_SEAL, &md5cksum))
 		return GSS_S_FAILURE;
 	buf->pages = tmp_pages;
@@ -200,7 +201,7 @@ gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset,
 			       seq_send, krb5_hdr + 16, krb5_hdr + 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;
 
@@ -223,6 +224,7 @@ 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;
 
@@ -294,7 +296,7 @@ gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf)
 	 * better to copy and encrypt at the same time. */
 
 	blocksize = crypto_blkcipher_blocksize(kctx->enc);
-	data_start = ptr + (16 - 2 + kctx->gk5e->cksumlength) + blocksize;
+	data_start = ptr + (16 - 2 + kctx->gk5e->cksumlength) + 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);