diff options
Diffstat (limited to 'kernel/arch/arm64/crypto/aes-ce-ccm-glue.c')
| -rw-r--r-- | kernel/arch/arm64/crypto/aes-ce-ccm-glue.c | 299 |
1 files changed, 299 insertions, 0 deletions
diff --git a/kernel/arch/arm64/crypto/aes-ce-ccm-glue.c b/kernel/arch/arm64/crypto/aes-ce-ccm-glue.c new file mode 100644 index 000000000..6c348df5b --- /dev/null +++ b/kernel/arch/arm64/crypto/aes-ce-ccm-glue.c @@ -0,0 +1,299 @@ +/* + * aes-ccm-glue.c - AES-CCM transform for ARMv8 with Crypto Extensions + * + * Copyright (C) 2013 - 2014 Linaro Ltd <ard.biesheuvel@linaro.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <asm/neon.h> +#include <asm/unaligned.h> +#include <crypto/aes.h> +#include <crypto/algapi.h> +#include <crypto/scatterwalk.h> +#include <linux/crypto.h> +#include <linux/module.h> + +#include "aes-ce-setkey.h" + +static int num_rounds(struct crypto_aes_ctx *ctx) +{ + /* + * # of rounds specified by AES: + * 128 bit key 10 rounds + * 192 bit key 12 rounds + * 256 bit key 14 rounds + * => n byte key => 6 + (n/4) rounds + */ + return 6 + ctx->key_length / 4; +} + +asmlinkage void ce_aes_ccm_auth_data(u8 mac[], u8 const in[], u32 abytes, + u32 *macp, u32 const rk[], u32 rounds); + +asmlinkage void ce_aes_ccm_encrypt(u8 out[], u8 const in[], u32 cbytes, + u32 const rk[], u32 rounds, u8 mac[], + u8 ctr[]); + +asmlinkage void ce_aes_ccm_decrypt(u8 out[], u8 const in[], u32 cbytes, + u32 const rk[], u32 rounds, u8 mac[], + u8 ctr[]); + +asmlinkage void ce_aes_ccm_final(u8 mac[], u8 const ctr[], u32 const rk[], + u32 rounds); + +static int ccm_setkey(struct crypto_aead *tfm, const u8 *in_key, + unsigned int key_len) +{ + struct crypto_aes_ctx *ctx = crypto_aead_ctx(tfm); + int ret; + + ret = ce_aes_expandkey(ctx, in_key, key_len); + if (!ret) + return 0; + + tfm->base.crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN; + return -EINVAL; +} + +static int ccm_setauthsize(struct crypto_aead *tfm, unsigned int authsize) +{ + if ((authsize & 1) || authsize < 4) + return -EINVAL; + return 0; +} + +static int ccm_init_mac(struct aead_request *req, u8 maciv[], u32 msglen) +{ + struct crypto_aead *aead = crypto_aead_reqtfm(req); + __be32 *n = (__be32 *)&maciv[AES_BLOCK_SIZE - 8]; + u32 l = req->iv[0] + 1; + + /* verify that CCM dimension 'L' is set correctly in the IV */ + if (l < 2 || l > 8) + return -EINVAL; + + /* verify that msglen can in fact be represented in L bytes */ + if (l < 4 && msglen >> (8 * l)) + return -EOVERFLOW; + + /* + * Even if the CCM spec allows L values of up to 8, the Linux cryptoapi + * uses a u32 type to represent msglen so the top 4 bytes are always 0. + */ + n[0] = 0; + n[1] = cpu_to_be32(msglen); + + memcpy(maciv, req->iv, AES_BLOCK_SIZE - l); + + /* + * Meaning of byte 0 according to CCM spec (RFC 3610/NIST 800-38C) + * - bits 0..2 : max # of bytes required to represent msglen, minus 1 + * (already set by caller) + * - bits 3..5 : size of auth tag (1 => 4 bytes, 2 => 6 bytes, etc) + * - bit 6 : indicates presence of authenticate-only data + */ + maciv[0] |= (crypto_aead_authsize(aead) - 2) << 2; + if (req->assoclen) + maciv[0] |= 0x40; + + memset(&req->iv[AES_BLOCK_SIZE - l], 0, l); + return 0; +} + +static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[]) +{ + struct crypto_aead *aead = crypto_aead_reqtfm(req); + struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead); + struct __packed { __be16 l; __be32 h; u16 len; } ltag; + struct scatter_walk walk; + u32 len = req->assoclen; + u32 macp = 0; + + /* prepend the AAD with a length tag */ + if (len < 0xff00) { + ltag.l = cpu_to_be16(len); + ltag.len = 2; + } else { + ltag.l = cpu_to_be16(0xfffe); + put_unaligned_be32(len, <ag.h); + ltag.len = 6; + } + + ce_aes_ccm_auth_data(mac, (u8 *)<ag, ltag.len, &macp, ctx->key_enc, + num_rounds(ctx)); + scatterwalk_start(&walk, req->assoc); + + do { + u32 n = scatterwalk_clamp(&walk, len); + u8 *p; + + if (!n) { + scatterwalk_start(&walk, sg_next(walk.sg)); + n = scatterwalk_clamp(&walk, len); + } + p = scatterwalk_map(&walk); + ce_aes_ccm_auth_data(mac, p, n, &macp, ctx->key_enc, + num_rounds(ctx)); + len -= n; + + scatterwalk_unmap(p); + scatterwalk_advance(&walk, n); + scatterwalk_done(&walk, 0, len); + } while (len); +} + +static int ccm_encrypt(struct aead_request *req) +{ + struct crypto_aead *aead = crypto_aead_reqtfm(req); + struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead); + struct blkcipher_desc desc = { .info = req->iv }; + struct blkcipher_walk walk; + u8 __aligned(8) mac[AES_BLOCK_SIZE]; + u8 buf[AES_BLOCK_SIZE]; + u32 len = req->cryptlen; + int err; + + err = ccm_init_mac(req, mac, len); + if (err) + return err; + + kernel_neon_begin_partial(6); + + if (req->assoclen) + ccm_calculate_auth_mac(req, mac); + + /* preserve the original iv for the final round */ + memcpy(buf, req->iv, AES_BLOCK_SIZE); + + blkcipher_walk_init(&walk, req->dst, req->src, len); + err = blkcipher_aead_walk_virt_block(&desc, &walk, aead, + AES_BLOCK_SIZE); + + while (walk.nbytes) { + u32 tail = walk.nbytes % AES_BLOCK_SIZE; + + if (walk.nbytes == len) + tail = 0; + + ce_aes_ccm_encrypt(walk.dst.virt.addr, walk.src.virt.addr, + walk.nbytes - tail, ctx->key_enc, + num_rounds(ctx), mac, walk.iv); + + len -= walk.nbytes - tail; + err = blkcipher_walk_done(&desc, &walk, tail); + } + if (!err) + ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx)); + + kernel_neon_end(); + + if (err) + return err; + + /* copy authtag to end of dst */ + scatterwalk_map_and_copy(mac, req->dst, req->cryptlen, + crypto_aead_authsize(aead), 1); + + return 0; +} + +static int ccm_decrypt(struct aead_request *req) +{ + struct crypto_aead *aead = crypto_aead_reqtfm(req); + struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead); + unsigned int authsize = crypto_aead_authsize(aead); + struct blkcipher_desc desc = { .info = req->iv }; + struct blkcipher_walk walk; + u8 __aligned(8) mac[AES_BLOCK_SIZE]; + u8 buf[AES_BLOCK_SIZE]; + u32 len = req->cryptlen - authsize; + int err; + + err = ccm_init_mac(req, mac, len); + if (err) + return err; + + kernel_neon_begin_partial(6); + + if (req->assoclen) + ccm_calculate_auth_mac(req, mac); + + /* preserve the original iv for the final round */ + memcpy(buf, req->iv, AES_BLOCK_SIZE); + + blkcipher_walk_init(&walk, req->dst, req->src, len); + err = blkcipher_aead_walk_virt_block(&desc, &walk, aead, + AES_BLOCK_SIZE); + + while (walk.nbytes) { + u32 tail = walk.nbytes % AES_BLOCK_SIZE; + + if (walk.nbytes == len) + tail = 0; + + ce_aes_ccm_decrypt(walk.dst.virt.addr, walk.src.virt.addr, + walk.nbytes - tail, ctx->key_enc, + num_rounds(ctx), mac, walk.iv); + + len -= walk.nbytes - tail; + err = blkcipher_walk_done(&desc, &walk, tail); + } + if (!err) + ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx)); + + kernel_neon_end(); + + if (err) + return err; + + /* compare calculated auth tag with the stored one */ + scatterwalk_map_and_copy(buf, req->src, req->cryptlen - authsize, + authsize, 0); + + if (memcmp(mac, buf, authsize)) + return -EBADMSG; + return 0; +} + +static struct crypto_alg ccm_aes_alg = { + .cra_name = "ccm(aes)", + .cra_driver_name = "ccm-aes-ce", + .cra_priority = 300, + .cra_flags = CRYPTO_ALG_TYPE_AEAD, + .cra_blocksize = 1, + .cra_ctxsize = sizeof(struct crypto_aes_ctx), + .cra_alignmask = 7, + .cra_type = &crypto_aead_type, + .cra_module = THIS_MODULE, + .cra_aead = { + .ivsize = AES_BLOCK_SIZE, + .maxauthsize = AES_BLOCK_SIZE, + .setkey = ccm_setkey, + .setauthsize = ccm_setauthsize, + .encrypt = ccm_encrypt, + .decrypt = ccm_decrypt, + } +}; + +static int __init aes_mod_init(void) +{ + if (!(elf_hwcap & HWCAP_AES)) + return -ENODEV; + return crypto_register_alg(&ccm_aes_alg); +} + +static void __exit aes_mod_exit(void) +{ + crypto_unregister_alg(&ccm_aes_alg); +} + +module_init(aes_mod_init); +module_exit(aes_mod_exit); + +MODULE_DESCRIPTION("Synchronous AES in CCM mode using ARMv8 Crypto Extensions"); +MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>"); +MODULE_LICENSE("GPL v2"); +MODULE_ALIAS_CRYPTO("ccm(aes)"); |