1/* 2 * aes-ccm-glue.c - AES-CCM transform for ARMv8 with Crypto Extensions 3 * 4 * Copyright (C) 2013 - 2014 Linaro Ltd <ard.biesheuvel@linaro.org> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 */ 10 11#include <asm/neon.h> 12#include <asm/unaligned.h> 13#include <crypto/aes.h> 14#include <crypto/algapi.h> 15#include <crypto/scatterwalk.h> 16#include <linux/crypto.h> 17#include <linux/module.h> 18 19#include "aes-ce-setkey.h" 20 21static int num_rounds(struct crypto_aes_ctx *ctx) 22{ 23 /* 24 * # of rounds specified by AES: 25 * 128 bit key 10 rounds 26 * 192 bit key 12 rounds 27 * 256 bit key 14 rounds 28 * => n byte key => 6 + (n/4) rounds 29 */ 30 return 6 + ctx->key_length / 4; 31} 32 33asmlinkage void ce_aes_ccm_auth_data(u8 mac[], u8 const in[], u32 abytes, 34 u32 *macp, u32 const rk[], u32 rounds); 35 36asmlinkage void ce_aes_ccm_encrypt(u8 out[], u8 const in[], u32 cbytes, 37 u32 const rk[], u32 rounds, u8 mac[], 38 u8 ctr[]); 39 40asmlinkage void ce_aes_ccm_decrypt(u8 out[], u8 const in[], u32 cbytes, 41 u32 const rk[], u32 rounds, u8 mac[], 42 u8 ctr[]); 43 44asmlinkage void ce_aes_ccm_final(u8 mac[], u8 const ctr[], u32 const rk[], 45 u32 rounds); 46 47static int ccm_setkey(struct crypto_aead *tfm, const u8 *in_key, 48 unsigned int key_len) 49{ 50 struct crypto_aes_ctx *ctx = crypto_aead_ctx(tfm); 51 int ret; 52 53 ret = ce_aes_expandkey(ctx, in_key, key_len); 54 if (!ret) 55 return 0; 56 57 tfm->base.crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN; 58 return -EINVAL; 59} 60 61static int ccm_setauthsize(struct crypto_aead *tfm, unsigned int authsize) 62{ 63 if ((authsize & 1) || authsize < 4) 64 return -EINVAL; 65 return 0; 66} 67 68static int ccm_init_mac(struct aead_request *req, u8 maciv[], u32 msglen) 69{ 70 struct crypto_aead *aead = crypto_aead_reqtfm(req); 71 __be32 *n = (__be32 *)&maciv[AES_BLOCK_SIZE - 8]; 72 u32 l = req->iv[0] + 1; 73 74 /* verify that CCM dimension 'L' is set correctly in the IV */ 75 if (l < 2 || l > 8) 76 return -EINVAL; 77 78 /* verify that msglen can in fact be represented in L bytes */ 79 if (l < 4 && msglen >> (8 * l)) 80 return -EOVERFLOW; 81 82 /* 83 * Even if the CCM spec allows L values of up to 8, the Linux cryptoapi 84 * uses a u32 type to represent msglen so the top 4 bytes are always 0. 85 */ 86 n[0] = 0; 87 n[1] = cpu_to_be32(msglen); 88 89 memcpy(maciv, req->iv, AES_BLOCK_SIZE - l); 90 91 /* 92 * Meaning of byte 0 according to CCM spec (RFC 3610/NIST 800-38C) 93 * - bits 0..2 : max # of bytes required to represent msglen, minus 1 94 * (already set by caller) 95 * - bits 3..5 : size of auth tag (1 => 4 bytes, 2 => 6 bytes, etc) 96 * - bit 6 : indicates presence of authenticate-only data 97 */ 98 maciv[0] |= (crypto_aead_authsize(aead) - 2) << 2; 99 if (req->assoclen) 100 maciv[0] |= 0x40; 101 102 memset(&req->iv[AES_BLOCK_SIZE - l], 0, l); 103 return 0; 104} 105 106static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[]) 107{ 108 struct crypto_aead *aead = crypto_aead_reqtfm(req); 109 struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead); 110 struct __packed { __be16 l; __be32 h; u16 len; } ltag; 111 struct scatter_walk walk; 112 u32 len = req->assoclen; 113 u32 macp = 0; 114 115 /* prepend the AAD with a length tag */ 116 if (len < 0xff00) { 117 ltag.l = cpu_to_be16(len); 118 ltag.len = 2; 119 } else { 120 ltag.l = cpu_to_be16(0xfffe); 121 put_unaligned_be32(len, <ag.h); 122 ltag.len = 6; 123 } 124 125 ce_aes_ccm_auth_data(mac, (u8 *)<ag, ltag.len, &macp, ctx->key_enc, 126 num_rounds(ctx)); 127 scatterwalk_start(&walk, req->assoc); 128 129 do { 130 u32 n = scatterwalk_clamp(&walk, len); 131 u8 *p; 132 133 if (!n) { 134 scatterwalk_start(&walk, sg_next(walk.sg)); 135 n = scatterwalk_clamp(&walk, len); 136 } 137 p = scatterwalk_map(&walk); 138 ce_aes_ccm_auth_data(mac, p, n, &macp, ctx->key_enc, 139 num_rounds(ctx)); 140 len -= n; 141 142 scatterwalk_unmap(p); 143 scatterwalk_advance(&walk, n); 144 scatterwalk_done(&walk, 0, len); 145 } while (len); 146} 147 148static int ccm_encrypt(struct aead_request *req) 149{ 150 struct crypto_aead *aead = crypto_aead_reqtfm(req); 151 struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead); 152 struct blkcipher_desc desc = { .info = req->iv }; 153 struct blkcipher_walk walk; 154 u8 __aligned(8) mac[AES_BLOCK_SIZE]; 155 u8 buf[AES_BLOCK_SIZE]; 156 u32 len = req->cryptlen; 157 int err; 158 159 err = ccm_init_mac(req, mac, len); 160 if (err) 161 return err; 162 163 kernel_neon_begin_partial(6); 164 165 if (req->assoclen) 166 ccm_calculate_auth_mac(req, mac); 167 168 /* preserve the original iv for the final round */ 169 memcpy(buf, req->iv, AES_BLOCK_SIZE); 170 171 blkcipher_walk_init(&walk, req->dst, req->src, len); 172 err = blkcipher_aead_walk_virt_block(&desc, &walk, aead, 173 AES_BLOCK_SIZE); 174 175 while (walk.nbytes) { 176 u32 tail = walk.nbytes % AES_BLOCK_SIZE; 177 178 if (walk.nbytes == len) 179 tail = 0; 180 181 ce_aes_ccm_encrypt(walk.dst.virt.addr, walk.src.virt.addr, 182 walk.nbytes - tail, ctx->key_enc, 183 num_rounds(ctx), mac, walk.iv); 184 185 len -= walk.nbytes - tail; 186 err = blkcipher_walk_done(&desc, &walk, tail); 187 } 188 if (!err) 189 ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx)); 190 191 kernel_neon_end(); 192 193 if (err) 194 return err; 195 196 /* copy authtag to end of dst */ 197 scatterwalk_map_and_copy(mac, req->dst, req->cryptlen, 198 crypto_aead_authsize(aead), 1); 199 200 return 0; 201} 202 203static int ccm_decrypt(struct aead_request *req) 204{ 205 struct crypto_aead *aead = crypto_aead_reqtfm(req); 206 struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead); 207 unsigned int authsize = crypto_aead_authsize(aead); 208 struct blkcipher_desc desc = { .info = req->iv }; 209 struct blkcipher_walk walk; 210 u8 __aligned(8) mac[AES_BLOCK_SIZE]; 211 u8 buf[AES_BLOCK_SIZE]; 212 u32 len = req->cryptlen - authsize; 213 int err; 214 215 err = ccm_init_mac(req, mac, len); 216 if (err) 217 return err; 218 219 kernel_neon_begin_partial(6); 220 221 if (req->assoclen) 222 ccm_calculate_auth_mac(req, mac); 223 224 /* preserve the original iv for the final round */ 225 memcpy(buf, req->iv, AES_BLOCK_SIZE); 226 227 blkcipher_walk_init(&walk, req->dst, req->src, len); 228 err = blkcipher_aead_walk_virt_block(&desc, &walk, aead, 229 AES_BLOCK_SIZE); 230 231 while (walk.nbytes) { 232 u32 tail = walk.nbytes % AES_BLOCK_SIZE; 233 234 if (walk.nbytes == len) 235 tail = 0; 236 237 ce_aes_ccm_decrypt(walk.dst.virt.addr, walk.src.virt.addr, 238 walk.nbytes - tail, ctx->key_enc, 239 num_rounds(ctx), mac, walk.iv); 240 241 len -= walk.nbytes - tail; 242 err = blkcipher_walk_done(&desc, &walk, tail); 243 } 244 if (!err) 245 ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx)); 246 247 kernel_neon_end(); 248 249 if (err) 250 return err; 251 252 /* compare calculated auth tag with the stored one */ 253 scatterwalk_map_and_copy(buf, req->src, req->cryptlen - authsize, 254 authsize, 0); 255 256 if (memcmp(mac, buf, authsize)) 257 return -EBADMSG; 258 return 0; 259} 260 261static struct crypto_alg ccm_aes_alg = { 262 .cra_name = "ccm(aes)", 263 .cra_driver_name = "ccm-aes-ce", 264 .cra_priority = 300, 265 .cra_flags = CRYPTO_ALG_TYPE_AEAD, 266 .cra_blocksize = 1, 267 .cra_ctxsize = sizeof(struct crypto_aes_ctx), 268 .cra_alignmask = 7, 269 .cra_type = &crypto_aead_type, 270 .cra_module = THIS_MODULE, 271 .cra_aead = { 272 .ivsize = AES_BLOCK_SIZE, 273 .maxauthsize = AES_BLOCK_SIZE, 274 .setkey = ccm_setkey, 275 .setauthsize = ccm_setauthsize, 276 .encrypt = ccm_encrypt, 277 .decrypt = ccm_decrypt, 278 } 279}; 280 281static int __init aes_mod_init(void) 282{ 283 if (!(elf_hwcap & HWCAP_AES)) 284 return -ENODEV; 285 return crypto_register_alg(&ccm_aes_alg); 286} 287 288static void __exit aes_mod_exit(void) 289{ 290 crypto_unregister_alg(&ccm_aes_alg); 291} 292 293module_init(aes_mod_init); 294module_exit(aes_mod_exit); 295 296MODULE_DESCRIPTION("Synchronous AES in CCM mode using ARMv8 Crypto Extensions"); 297MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>"); 298MODULE_LICENSE("GPL v2"); 299MODULE_ALIAS_CRYPTO("ccm(aes)"); 300