/* * aes-ccm-glue.c - AES-CCM transform for ARMv8 with Crypto Extensions * * Copyright (C) 2013 - 2014 Linaro Ltd * * 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 #include #include #include #include #include #include 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 = crypto_aes_expand_key(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 "); MODULE_LICENSE("GPL v2"); MODULE_ALIAS("ccm(aes)");