rpc: spkm3 update

This updates the spkm3 code to bring it up to date with our current
understanding of the spkm3 spec.

In doing so, we're changing the downcall format used by gssd in the spkm3 case,
which will cause an incompatilibity with old userland spkm3 support.  Since the
old code a) didn't implement the protocol correctly, and b) was never
distributed except in the form of some experimental patches from the citi web
site, we're assuming this is OK.

We do detect the old downcall format and print warning (and fail).  We also
include a version number in the new downcall format, to be used in the
future in case any further change is required.

In some more detail:

	- fix integrity support
	- removed dependency on NIDs. instead OIDs are used
	- known OID values for algorithms added.
	- fixed some context fields and types

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 80 insertions, 21 deletions

diff --git a/net/sunrpc/auth_gss/gss_spkm3_seal.c b/net/sunrpc/auth_gss/gss_spkm3_seal.c
index 18c7862bc234..b179d58c6249 100644
--- a/net/sunrpc/auth_gss/gss_spkm3_seal.c
+++ b/net/sunrpc/auth_gss/gss_spkm3_seal.c
@@ -39,11 +39,17 @@
 #include <linux/sunrpc/gss_spkm3.h>
 #include <linux/random.h>
 #include <linux/crypto.h>
+#include <linux/pagemap.h>
+#include <linux/scatterlist.h>
+#include <linux/sunrpc/xdr.h>
 
 #ifdef RPC_DEBUG
 # define RPCDBG_FACILITY        RPCDBG_AUTH
 #endif
 
+const struct xdr_netobj hmac_md5_oid = { 8, "\x2B\x06\x01\x05\x05\x08\x01\x01"};
+const struct xdr_netobj cast5_cbc_oid = {9, "\x2A\x86\x48\x86\xF6\x7D\x07\x42\x0A"};
+
 /*
  * spkm3_make_token()
  *
@@ -66,29 +72,23 @@ spkm3_make_token(struct spkm3_ctx *ctx,
 	int			ctxelen = 0, ctxzbit = 0;
 	int			md5elen = 0, md5zbit = 0;
 
-	dprintk("RPC: spkm3_make_token\n");
-
 	now = jiffies;
 
 	if (ctx->ctx_id.len != 16) {
 		dprintk("RPC: spkm3_make_token BAD ctx_id.len %d\n",
-			ctx->ctx_id.len);
+				ctx->ctx_id.len);
 		goto out_err;
 	}
-		
-	switch (ctx->intg_alg) {
-		case NID_md5:
-			checksum_type = CKSUMTYPE_RSA_MD5;
-			break;
-		default:
-			dprintk("RPC: gss_spkm3_seal: ctx->signalg %d not"
-				" supported\n", ctx->intg_alg);
-			goto out_err;
-	}
-	/* XXX since we don't support WRAP, perhaps we don't care... */
-	if (ctx->conf_alg != NID_cast5_cbc) {
-		dprintk("RPC: gss_spkm3_seal: ctx->sealalg %d not supported\n",
-			ctx->conf_alg);
+
+	if (!g_OID_equal(&ctx->intg_alg, &hmac_md5_oid)) {
+		dprintk("RPC: gss_spkm3_seal: unsupported I-ALG algorithm."
+				"only support hmac-md5 I-ALG.\n");
+		goto out_err;
+	} else
+		checksum_type = CKSUMTYPE_HMAC_MD5;
+
+	if (!g_OID_equal(&ctx->conf_alg, &cast5_cbc_oid)) {
+		dprintk("RPC: gss_spkm3_seal: unsupported C-ALG algorithm\n");
 		goto out_err;
 	}
 
@@ -96,10 +96,10 @@ spkm3_make_token(struct spkm3_ctx *ctx,
 		/* Calculate checksum over the mic-header */
 		asn1_bitstring_len(&ctx->ctx_id, &ctxelen, &ctxzbit);
 		spkm3_mic_header(&mic_hdr.data, &mic_hdr.len, ctx->ctx_id.data,
-		                         ctxelen, ctxzbit);
-
-		if (make_checksum(checksum_type, mic_hdr.data, mic_hdr.len, 
-		                             text, 0, &md5cksum))
+				ctxelen, ctxzbit);
+		if (make_spkm3_checksum(checksum_type, &ctx->derived_integ_key,
+					(char *)mic_hdr.data, mic_hdr.len,
+					text, 0, &md5cksum))
 			goto out_err;
 
 		asn1_bitstring_len(&md5cksum, &md5elen, &md5zbit);
@@ -121,7 +121,66 @@ spkm3_make_token(struct spkm3_ctx *ctx,
 
 	return  GSS_S_COMPLETE;
 out_err:
+	if (md5cksum.data)
+		kfree(md5cksum.data);
+
 	token->data = NULL;
 	token->len = 0;
 	return GSS_S_FAILURE;
 }
+
+static int
+spkm3_checksummer(struct scatterlist *sg, void *data)
+{
+	struct hash_desc *desc = data;
+
+	return crypto_hash_update(desc, sg, sg->length);
+}
+
+/* checksum the plaintext data and hdrlen bytes of the token header */
+s32
+make_spkm3_checksum(s32 cksumtype, struct xdr_netobj *key, char *header,
+		    unsigned int hdrlen, struct xdr_buf *body,
+		    unsigned int body_offset, struct xdr_netobj *cksum)
+{
+	char				*cksumname;
+	struct hash_desc		desc; /* XXX add to ctx? */
+	struct scatterlist		sg[1];
+	int err;
+
+	switch (cksumtype) {
+		case CKSUMTYPE_HMAC_MD5:
+			cksumname = "md5";
+			break;
+		default:
+			dprintk("RPC:      spkm3_make_checksum:"
+					" unsupported checksum %d", cksumtype);
+			return GSS_S_FAILURE;
+	}
+
+	if (key->data == NULL || key->len <= 0) return GSS_S_FAILURE;
+
+	desc.tfm = crypto_alloc_hash(cksumname, 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;
+
+	err = crypto_hash_setkey(desc.tfm, key->data, key->len);
+	if (err)
+		goto out;
+
+	sg_set_buf(sg, header, hdrlen);
+	crypto_hash_update(&desc, sg, 1);
+
+	xdr_process_buf(body, body_offset, body->len - body_offset,
+			spkm3_checksummer, &desc);
+	crypto_hash_final(&desc, cksum->data);
+
+out:
+	crypto_free_hash(desc.tfm);
+
+	return err ? GSS_S_FAILURE : 0;
+}
+
+EXPORT_SYMBOL(make_spkm3_checksum);