1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * aes-ccm-glue.c - AES-CCM transform for ARMv8 with Crypto Extensions 4 * 5 * Copyright (C) 2013 - 2017 Linaro Ltd <ard.biesheuvel@linaro.org> 6 */ 7 8 #include <asm/neon.h> 9 #include <asm/unaligned.h> 10 #include <crypto/aes.h> 11 #include <crypto/scatterwalk.h> 12 #include <crypto/internal/aead.h> 13 #include <crypto/internal/skcipher.h> 14 #include <linux/module.h> 15 16 #include "aes-ce-setkey.h" 17 18 static int num_rounds(struct crypto_aes_ctx *ctx) 19 { 20 /* 21 * # of rounds specified by AES: 22 * 128 bit key 10 rounds 23 * 192 bit key 12 rounds 24 * 256 bit key 14 rounds 25 * => n byte key => 6 + (n/4) rounds 26 */ 27 return 6 + ctx->key_length / 4; 28 } 29 30 asmlinkage void ce_aes_ccm_auth_data(u8 mac[], u8 const in[], u32 abytes, 31 u32 *macp, u32 const rk[], u32 rounds); 32 33 asmlinkage void ce_aes_ccm_encrypt(u8 out[], u8 const in[], u32 cbytes, 34 u32 const rk[], u32 rounds, u8 mac[], 35 u8 ctr[]); 36 37 asmlinkage void ce_aes_ccm_decrypt(u8 out[], u8 const in[], u32 cbytes, 38 u32 const rk[], u32 rounds, u8 mac[], 39 u8 ctr[]); 40 41 asmlinkage void ce_aes_ccm_final(u8 mac[], u8 const ctr[], u32 const rk[], 42 u32 rounds); 43 44 static int ccm_setkey(struct crypto_aead *tfm, const u8 *in_key, 45 unsigned int key_len) 46 { 47 struct crypto_aes_ctx *ctx = crypto_aead_ctx(tfm); 48 49 return ce_aes_expandkey(ctx, in_key, key_len); 50 } 51 52 static int ccm_setauthsize(struct crypto_aead *tfm, unsigned int authsize) 53 { 54 if ((authsize & 1) || authsize < 4) 55 return -EINVAL; 56 return 0; 57 } 58 59 static int ccm_init_mac(struct aead_request *req, u8 maciv[], u32 msglen) 60 { 61 struct crypto_aead *aead = crypto_aead_reqtfm(req); 62 __be32 *n = (__be32 *)&maciv[AES_BLOCK_SIZE - 8]; 63 u32 l = req->iv[0] + 1; 64 65 /* verify that CCM dimension 'L' is set correctly in the IV */ 66 if (l < 2 || l > 8) 67 return -EINVAL; 68 69 /* verify that msglen can in fact be represented in L bytes */ 70 if (l < 4 && msglen >> (8 * l)) 71 return -EOVERFLOW; 72 73 /* 74 * Even if the CCM spec allows L values of up to 8, the Linux cryptoapi 75 * uses a u32 type to represent msglen so the top 4 bytes are always 0. 76 */ 77 n[0] = 0; 78 n[1] = cpu_to_be32(msglen); 79 80 memcpy(maciv, req->iv, AES_BLOCK_SIZE - l); 81 82 /* 83 * Meaning of byte 0 according to CCM spec (RFC 3610/NIST 800-38C) 84 * - bits 0..2 : max # of bytes required to represent msglen, minus 1 85 * (already set by caller) 86 * - bits 3..5 : size of auth tag (1 => 4 bytes, 2 => 6 bytes, etc) 87 * - bit 6 : indicates presence of authenticate-only data 88 */ 89 maciv[0] |= (crypto_aead_authsize(aead) - 2) << 2; 90 if (req->assoclen) 91 maciv[0] |= 0x40; 92 93 memset(&req->iv[AES_BLOCK_SIZE - l], 0, l); 94 return 0; 95 } 96 97 static void ccm_update_mac(struct crypto_aes_ctx *key, u8 mac[], u8 const in[], 98 u32 abytes, u32 *macp) 99 { 100 kernel_neon_begin(); 101 ce_aes_ccm_auth_data(mac, in, abytes, macp, key->key_enc, 102 num_rounds(key)); 103 kernel_neon_end(); 104 } 105 106 static 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 ccm_update_mac(ctx, mac, (u8 *)<ag, ltag.len, &macp); 126 scatterwalk_start(&walk, req->src); 127 128 do { 129 u32 n = scatterwalk_clamp(&walk, len); 130 u8 *p; 131 132 if (!n) { 133 scatterwalk_start(&walk, sg_next(walk.sg)); 134 n = scatterwalk_clamp(&walk, len); 135 } 136 n = min_t(u32, n, SZ_4K); /* yield NEON at least every 4k */ 137 p = scatterwalk_map(&walk); 138 ccm_update_mac(ctx, mac, p, n, &macp); 139 len -= n; 140 141 scatterwalk_unmap(p); 142 scatterwalk_advance(&walk, n); 143 scatterwalk_done(&walk, 0, len); 144 } while (len); 145 } 146 147 static int ccm_encrypt(struct aead_request *req) 148 { 149 struct crypto_aead *aead = crypto_aead_reqtfm(req); 150 struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead); 151 struct skcipher_walk walk; 152 u8 __aligned(8) mac[AES_BLOCK_SIZE]; 153 u8 buf[AES_BLOCK_SIZE]; 154 u32 len = req->cryptlen; 155 int err; 156 157 err = ccm_init_mac(req, mac, len); 158 if (err) 159 return err; 160 161 if (req->assoclen) 162 ccm_calculate_auth_mac(req, mac); 163 164 /* preserve the original iv for the final round */ 165 memcpy(buf, req->iv, AES_BLOCK_SIZE); 166 167 err = skcipher_walk_aead_encrypt(&walk, req, false); 168 169 while (walk.nbytes) { 170 u32 tail = walk.nbytes % AES_BLOCK_SIZE; 171 172 if (walk.nbytes == walk.total) 173 tail = 0; 174 175 kernel_neon_begin(); 176 ce_aes_ccm_encrypt(walk.dst.virt.addr, walk.src.virt.addr, 177 walk.nbytes - tail, ctx->key_enc, 178 num_rounds(ctx), mac, walk.iv); 179 kernel_neon_end(); 180 181 err = skcipher_walk_done(&walk, tail); 182 } 183 if (!err) { 184 kernel_neon_begin(); 185 ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx)); 186 kernel_neon_end(); 187 } 188 if (err) 189 return err; 190 191 /* copy authtag to end of dst */ 192 scatterwalk_map_and_copy(mac, req->dst, req->assoclen + req->cryptlen, 193 crypto_aead_authsize(aead), 1); 194 195 return 0; 196 } 197 198 static int ccm_decrypt(struct aead_request *req) 199 { 200 struct crypto_aead *aead = crypto_aead_reqtfm(req); 201 struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead); 202 unsigned int authsize = crypto_aead_authsize(aead); 203 struct skcipher_walk walk; 204 u8 __aligned(8) mac[AES_BLOCK_SIZE]; 205 u8 buf[AES_BLOCK_SIZE]; 206 u32 len = req->cryptlen - authsize; 207 int err; 208 209 err = ccm_init_mac(req, mac, len); 210 if (err) 211 return err; 212 213 if (req->assoclen) 214 ccm_calculate_auth_mac(req, mac); 215 216 /* preserve the original iv for the final round */ 217 memcpy(buf, req->iv, AES_BLOCK_SIZE); 218 219 err = skcipher_walk_aead_decrypt(&walk, req, false); 220 221 while (walk.nbytes) { 222 u32 tail = walk.nbytes % AES_BLOCK_SIZE; 223 224 if (walk.nbytes == walk.total) 225 tail = 0; 226 227 kernel_neon_begin(); 228 ce_aes_ccm_decrypt(walk.dst.virt.addr, walk.src.virt.addr, 229 walk.nbytes - tail, ctx->key_enc, 230 num_rounds(ctx), mac, walk.iv); 231 kernel_neon_end(); 232 233 err = skcipher_walk_done(&walk, tail); 234 } 235 if (!err) { 236 kernel_neon_begin(); 237 ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx)); 238 kernel_neon_end(); 239 } 240 if (err) 241 return err; 242 243 /* compare calculated auth tag with the stored one */ 244 scatterwalk_map_and_copy(buf, req->src, 245 req->assoclen + req->cryptlen - authsize, 246 authsize, 0); 247 248 if (crypto_memneq(mac, buf, authsize)) 249 return -EBADMSG; 250 return 0; 251 } 252 253 static struct aead_alg ccm_aes_alg = { 254 .base = { 255 .cra_name = "ccm(aes)", 256 .cra_driver_name = "ccm-aes-ce", 257 .cra_priority = 300, 258 .cra_blocksize = 1, 259 .cra_ctxsize = sizeof(struct crypto_aes_ctx), 260 .cra_module = THIS_MODULE, 261 }, 262 .ivsize = AES_BLOCK_SIZE, 263 .chunksize = AES_BLOCK_SIZE, 264 .maxauthsize = AES_BLOCK_SIZE, 265 .setkey = ccm_setkey, 266 .setauthsize = ccm_setauthsize, 267 .encrypt = ccm_encrypt, 268 .decrypt = ccm_decrypt, 269 }; 270 271 static int __init aes_mod_init(void) 272 { 273 if (!cpu_have_named_feature(AES)) 274 return -ENODEV; 275 return crypto_register_aead(&ccm_aes_alg); 276 } 277 278 static void __exit aes_mod_exit(void) 279 { 280 crypto_unregister_aead(&ccm_aes_alg); 281 } 282 283 module_init(aes_mod_init); 284 module_exit(aes_mod_exit); 285 286 MODULE_DESCRIPTION("Synchronous AES in CCM mode using ARMv8 Crypto Extensions"); 287 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>"); 288 MODULE_LICENSE("GPL v2"); 289 MODULE_ALIAS_CRYPTO("ccm(aes)"); 290