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Commit 41e3173d authored by Marcelo Cerri's avatar Marcelo Cerri Committed by Herbert Xu
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crypto: nx - fix XCBC for zero length messages 



The NX XCBC implementation doesn't support zero length messages and
because of that NX is currently returning a hard-coded hash for zero
length messages. However this approach is incorrect since the hash value
also depends on which key is used.

This patch removes the hard-coded hash and replace it with an
implementation based on the RFC 3566 using ECB.

Reviewed-by: default avatarJoy Latten <jmlatten@linux.vnet.ibm.com>
Signed-off-by: default avatarMarcelo Cerri <mhcerri@linux.vnet.ibm.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 2b188b3b

drivers/crypto/nx/nx-aes-xcbc.c

+77 −7
Original line number Diff line number Diff line
@@ -56,6 +56,77 @@ static int nx_xcbc_set_key(struct crypto_shash *desc, 
	return 0;

}



/*

 * Based on RFC 3566, for a zero-length message:

 *

 * n = 1

 * K1 = E(K, 0x01010101010101010101010101010101)

 * K3 = E(K, 0x03030303030303030303030303030303)

 * E[0] = 0x00000000000000000000000000000000

 * M[1] = 0x80000000000000000000000000000000 (0 length message with padding)

 * E[1] = (K1, M[1] ^ E[0] ^ K3)

 * Tag = M[1]

 */

static int nx_xcbc_empty(struct shash_desc *desc, u8 *out)

{

	struct nx_crypto_ctx *nx_ctx = crypto_tfm_ctx(&desc->tfm->base);

	struct nx_csbcpb *csbcpb = nx_ctx->csbcpb;

	struct nx_sg *in_sg, *out_sg;

	u8 keys[2][AES_BLOCK_SIZE];

	u8 key[32];

	int rc = 0;



	/* Change to ECB mode */

	csbcpb->cpb.hdr.mode = NX_MODE_AES_ECB;

	memcpy(key, csbcpb->cpb.aes_xcbc.key, AES_BLOCK_SIZE);

	memcpy(csbcpb->cpb.aes_ecb.key, key, AES_BLOCK_SIZE);

	NX_CPB_FDM(csbcpb) |= NX_FDM_ENDE_ENCRYPT;



	/* K1 and K3 base patterns */

	memset(keys[0], 0x01, sizeof(keys[0]));

	memset(keys[1], 0x03, sizeof(keys[1]));



	/* Generate K1 and K3 encrypting the patterns */

	in_sg = nx_build_sg_list(nx_ctx->in_sg, (u8 *) keys, sizeof(keys),

				 nx_ctx->ap->sglen);

	out_sg = nx_build_sg_list(nx_ctx->out_sg, (u8 *) keys, sizeof(keys),

				  nx_ctx->ap->sglen);

	nx_ctx->op.inlen = (nx_ctx->in_sg - in_sg) * sizeof(struct nx_sg);

	nx_ctx->op.outlen = (nx_ctx->out_sg - out_sg) * sizeof(struct nx_sg);



	rc = nx_hcall_sync(nx_ctx, &nx_ctx->op,

			   desc->flags & CRYPTO_TFM_REQ_MAY_SLEEP);

	if (rc)

		goto out;

	atomic_inc(&(nx_ctx->stats->aes_ops));



	/* XOr K3 with the padding for a 0 length message */

	keys[1][0] ^= 0x80;



	/* Encrypt the final result */

	memcpy(csbcpb->cpb.aes_ecb.key, keys[0], AES_BLOCK_SIZE);

	in_sg = nx_build_sg_list(nx_ctx->in_sg, (u8 *) keys[1], sizeof(keys[1]),

				 nx_ctx->ap->sglen);

	out_sg = nx_build_sg_list(nx_ctx->out_sg, out, AES_BLOCK_SIZE,

				  nx_ctx->ap->sglen);

	nx_ctx->op.inlen = (nx_ctx->in_sg - in_sg) * sizeof(struct nx_sg);

	nx_ctx->op.outlen = (nx_ctx->out_sg - out_sg) * sizeof(struct nx_sg);



	rc = nx_hcall_sync(nx_ctx, &nx_ctx->op,

			   desc->flags & CRYPTO_TFM_REQ_MAY_SLEEP);

	if (rc)

		goto out;

	atomic_inc(&(nx_ctx->stats->aes_ops));



out:

	/* Restore XCBC mode */

	csbcpb->cpb.hdr.mode = NX_MODE_AES_XCBC_MAC;

	memcpy(csbcpb->cpb.aes_xcbc.key, key, AES_BLOCK_SIZE);

	NX_CPB_FDM(csbcpb) &= ~NX_FDM_ENDE_ENCRYPT;



	return rc;

}



static int nx_xcbc_init(struct shash_desc *desc)

{

	struct xcbc_state *sctx = shash_desc_ctx(desc);
@@ -201,13 +272,12 @@ static int nx_xcbc_final(struct shash_desc *desc, u8 *out) 
		memcpy(csbcpb->cpb.aes_xcbc.cv,

		       csbcpb->cpb.aes_xcbc.out_cv_mac, AES_BLOCK_SIZE);

	} else if (sctx->count == 0) {

		/* we've never seen an update, so this is a 0 byte op. The

		 * hardware cannot handle a 0 byte op, so just copy out the

		 * known 0 byte result. This is cheaper than allocating a

		 * software context to do a 0 byte op */

		u8 data[] = { 0x75, 0xf0, 0x25, 0x1d, 0x52, 0x8a, 0xc0, 0x1c,

			      0x45, 0x73, 0xdf, 0xd5, 0x84, 0xd7, 0x9f, 0x29 };

		memcpy(out, data, sizeof(data));

		/*

		 * we've never seen an update, so this is a 0 byte op. The

		 * hardware cannot handle a 0 byte op, so just ECB to

		 * generate the hash.

		 */

		rc = nx_xcbc_empty(desc, out);

		goto out;

	}