[PATCH v2 08/10] crypto: nx - fix XCBC for zero length messages
From: Marcelo Cerri <hidden>
Date: 2013-08-29 14:37:40
Also in:
linux-crypto, lkml
Subsystem:
crypto api, ibm power in-nest crypto acceleration, linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Herbert Xu, "David S. Miller", Breno Leitão, Nayna Jain, Paulo Flabiano Smorigo, Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
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: Joy Latten <redacted> Signed-off-by: Marcelo Cerri <redacted> --- drivers/crypto/nx/nx-aes-xcbc.c | 84 +++++++++++++++++++++++++++++++++++++---- 1 file changed, 77 insertions(+), 7 deletions(-)
diff --git a/drivers/crypto/nx/nx-aes-xcbc.c b/drivers/crypto/nx/nx-aes-xcbc.c
index 1a5d9e3..03c4bf5 100644
--- a/drivers/crypto/nx/nx-aes-xcbc.c
+++ b/drivers/crypto/nx/nx-aes-xcbc.c@@ -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; }
--
1.7.12