300 lines
7.5 KiB
C
300 lines
7.5 KiB
C
/*
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* aes-ccm-glue.c - AES-CCM transform for ARMv8 with Crypto Extensions
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*
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* Copyright (C) 2013 - 2014 Linaro Ltd <ard.biesheuvel@linaro.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <asm/neon.h>
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#include <asm/unaligned.h>
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#include <crypto/aes.h>
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#include <crypto/algapi.h>
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#include <crypto/scatterwalk.h>
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#include <crypto/internal/aead.h>
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#include <linux/module.h>
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#include "aes-ce-setkey.h"
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static int num_rounds(struct crypto_aes_ctx *ctx)
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{
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/*
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* # of rounds specified by AES:
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* 128 bit key 10 rounds
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* 192 bit key 12 rounds
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* 256 bit key 14 rounds
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* => n byte key => 6 + (n/4) rounds
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*/
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return 6 + ctx->key_length / 4;
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}
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asmlinkage void ce_aes_ccm_auth_data(u8 mac[], u8 const in[], u32 abytes,
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u32 *macp, u32 const rk[], u32 rounds);
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asmlinkage void ce_aes_ccm_encrypt(u8 out[], u8 const in[], u32 cbytes,
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u32 const rk[], u32 rounds, u8 mac[],
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u8 ctr[]);
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asmlinkage void ce_aes_ccm_decrypt(u8 out[], u8 const in[], u32 cbytes,
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u32 const rk[], u32 rounds, u8 mac[],
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u8 ctr[]);
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asmlinkage void ce_aes_ccm_final(u8 mac[], u8 const ctr[], u32 const rk[],
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u32 rounds);
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static int ccm_setkey(struct crypto_aead *tfm, const u8 *in_key,
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unsigned int key_len)
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{
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struct crypto_aes_ctx *ctx = crypto_aead_ctx(tfm);
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int ret;
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ret = ce_aes_expandkey(ctx, in_key, key_len);
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if (!ret)
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return 0;
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tfm->base.crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
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return -EINVAL;
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}
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static int ccm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
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{
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if ((authsize & 1) || authsize < 4)
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return -EINVAL;
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return 0;
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}
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static int ccm_init_mac(struct aead_request *req, u8 maciv[], u32 msglen)
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{
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struct crypto_aead *aead = crypto_aead_reqtfm(req);
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__be32 *n = (__be32 *)&maciv[AES_BLOCK_SIZE - 8];
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u32 l = req->iv[0] + 1;
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/* verify that CCM dimension 'L' is set correctly in the IV */
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if (l < 2 || l > 8)
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return -EINVAL;
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/* verify that msglen can in fact be represented in L bytes */
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if (l < 4 && msglen >> (8 * l))
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return -EOVERFLOW;
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/*
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* Even if the CCM spec allows L values of up to 8, the Linux cryptoapi
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* uses a u32 type to represent msglen so the top 4 bytes are always 0.
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*/
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n[0] = 0;
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n[1] = cpu_to_be32(msglen);
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memcpy(maciv, req->iv, AES_BLOCK_SIZE - l);
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/*
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* Meaning of byte 0 according to CCM spec (RFC 3610/NIST 800-38C)
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* - bits 0..2 : max # of bytes required to represent msglen, minus 1
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* (already set by caller)
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* - bits 3..5 : size of auth tag (1 => 4 bytes, 2 => 6 bytes, etc)
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* - bit 6 : indicates presence of authenticate-only data
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*/
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maciv[0] |= (crypto_aead_authsize(aead) - 2) << 2;
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if (req->assoclen)
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maciv[0] |= 0x40;
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memset(&req->iv[AES_BLOCK_SIZE - l], 0, l);
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return 0;
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}
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static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[])
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{
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struct crypto_aead *aead = crypto_aead_reqtfm(req);
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struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
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struct __packed { __be16 l; __be32 h; u16 len; } ltag;
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struct scatter_walk walk;
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u32 len = req->assoclen;
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u32 macp = 0;
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/* prepend the AAD with a length tag */
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if (len < 0xff00) {
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ltag.l = cpu_to_be16(len);
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ltag.len = 2;
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} else {
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ltag.l = cpu_to_be16(0xfffe);
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put_unaligned_be32(len, <ag.h);
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ltag.len = 6;
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}
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ce_aes_ccm_auth_data(mac, (u8 *)<ag, ltag.len, &macp, ctx->key_enc,
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num_rounds(ctx));
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scatterwalk_start(&walk, req->assoc);
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do {
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u32 n = scatterwalk_clamp(&walk, len);
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u8 *p;
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if (!n) {
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scatterwalk_start(&walk, sg_next(walk.sg));
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n = scatterwalk_clamp(&walk, len);
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}
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p = scatterwalk_map(&walk);
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ce_aes_ccm_auth_data(mac, p, n, &macp, ctx->key_enc,
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num_rounds(ctx));
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len -= n;
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scatterwalk_unmap(p);
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scatterwalk_advance(&walk, n);
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scatterwalk_done(&walk, 0, len);
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} while (len);
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}
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static int ccm_encrypt(struct aead_request *req)
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{
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struct crypto_aead *aead = crypto_aead_reqtfm(req);
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struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
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struct blkcipher_desc desc = { .info = req->iv };
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struct blkcipher_walk walk;
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u8 __aligned(8) mac[AES_BLOCK_SIZE];
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u8 buf[AES_BLOCK_SIZE];
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u32 len = req->cryptlen;
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int err;
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err = ccm_init_mac(req, mac, len);
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if (err)
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return err;
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kernel_neon_begin_partial(6);
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if (req->assoclen)
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ccm_calculate_auth_mac(req, mac);
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/* preserve the original iv for the final round */
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memcpy(buf, req->iv, AES_BLOCK_SIZE);
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blkcipher_walk_init(&walk, req->dst, req->src, len);
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err = blkcipher_aead_walk_virt_block(&desc, &walk, aead,
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AES_BLOCK_SIZE);
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while (walk.nbytes) {
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u32 tail = walk.nbytes % AES_BLOCK_SIZE;
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if (walk.nbytes == len)
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tail = 0;
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ce_aes_ccm_encrypt(walk.dst.virt.addr, walk.src.virt.addr,
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walk.nbytes - tail, ctx->key_enc,
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num_rounds(ctx), mac, walk.iv);
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len -= walk.nbytes - tail;
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err = blkcipher_walk_done(&desc, &walk, tail);
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}
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if (!err)
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ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx));
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kernel_neon_end();
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if (err)
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return err;
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/* copy authtag to end of dst */
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scatterwalk_map_and_copy(mac, req->dst, req->cryptlen,
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crypto_aead_authsize(aead), 1);
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return 0;
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}
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static int ccm_decrypt(struct aead_request *req)
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{
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struct crypto_aead *aead = crypto_aead_reqtfm(req);
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struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
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unsigned int authsize = crypto_aead_authsize(aead);
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struct blkcipher_desc desc = { .info = req->iv };
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struct blkcipher_walk walk;
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u8 __aligned(8) mac[AES_BLOCK_SIZE];
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u8 buf[AES_BLOCK_SIZE];
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u32 len = req->cryptlen - authsize;
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int err;
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err = ccm_init_mac(req, mac, len);
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if (err)
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return err;
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kernel_neon_begin_partial(6);
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if (req->assoclen)
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ccm_calculate_auth_mac(req, mac);
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/* preserve the original iv for the final round */
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memcpy(buf, req->iv, AES_BLOCK_SIZE);
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blkcipher_walk_init(&walk, req->dst, req->src, len);
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err = blkcipher_aead_walk_virt_block(&desc, &walk, aead,
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AES_BLOCK_SIZE);
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while (walk.nbytes) {
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u32 tail = walk.nbytes % AES_BLOCK_SIZE;
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if (walk.nbytes == len)
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tail = 0;
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ce_aes_ccm_decrypt(walk.dst.virt.addr, walk.src.virt.addr,
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walk.nbytes - tail, ctx->key_enc,
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num_rounds(ctx), mac, walk.iv);
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len -= walk.nbytes - tail;
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err = blkcipher_walk_done(&desc, &walk, tail);
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}
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if (!err)
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ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx));
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kernel_neon_end();
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if (err)
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return err;
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/* compare calculated auth tag with the stored one */
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scatterwalk_map_and_copy(buf, req->src, req->cryptlen - authsize,
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authsize, 0);
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if (memcmp(mac, buf, authsize))
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return -EBADMSG;
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return 0;
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}
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static struct crypto_alg ccm_aes_alg = {
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.cra_name = "ccm(aes)",
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.cra_driver_name = "ccm-aes-ce",
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.cra_priority = 300,
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.cra_flags = CRYPTO_ALG_TYPE_AEAD,
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.cra_blocksize = 1,
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.cra_ctxsize = sizeof(struct crypto_aes_ctx),
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.cra_alignmask = 7,
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.cra_type = &crypto_aead_type,
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.cra_module = THIS_MODULE,
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.cra_aead = {
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.ivsize = AES_BLOCK_SIZE,
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.maxauthsize = AES_BLOCK_SIZE,
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.setkey = ccm_setkey,
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.setauthsize = ccm_setauthsize,
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.encrypt = ccm_encrypt,
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.decrypt = ccm_decrypt,
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}
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};
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static int __init aes_mod_init(void)
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{
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if (!(elf_hwcap & HWCAP_AES))
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return -ENODEV;
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return crypto_register_alg(&ccm_aes_alg);
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}
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static void __exit aes_mod_exit(void)
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{
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crypto_unregister_alg(&ccm_aes_alg);
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}
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module_init(aes_mod_init);
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module_exit(aes_mod_exit);
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MODULE_DESCRIPTION("Synchronous AES in CCM mode using ARMv8 Crypto Extensions");
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MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
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MODULE_LICENSE("GPL v2");
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MODULE_ALIAS_CRYPTO("ccm(aes)");
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