1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * SM4-CCM AEAD Algorithm using ARMv8 Crypto Extensions 4 * as specified in rfc8998 5 * https://datatracker.ietf.org/doc/html/rfc8998 6 * 7 * Copyright (C) 2022 Tianjia Zhang <tianjia.zhang@linux.alibaba.com> 8 */ 9 10 #include <linux/module.h> 11 #include <linux/crypto.h> 12 #include <linux/kernel.h> 13 #include <linux/cpufeature.h> 14 #include <asm/neon.h> 15 #include <crypto/scatterwalk.h> 16 #include <crypto/internal/aead.h> 17 #include <crypto/internal/skcipher.h> 18 #include <crypto/sm4.h> 19 #include "sm4-ce.h" 20 21 asmlinkage void sm4_ce_cbcmac_update(const u32 *rkey_enc, u8 *mac, 22 const u8 *src, unsigned int nblocks); 23 asmlinkage void sm4_ce_ccm_enc(const u32 *rkey_enc, u8 *dst, const u8 *src, 24 u8 *iv, unsigned int nbytes, u8 *mac); 25 asmlinkage void sm4_ce_ccm_dec(const u32 *rkey_enc, u8 *dst, const u8 *src, 26 u8 *iv, unsigned int nbytes, u8 *mac); 27 asmlinkage void sm4_ce_ccm_final(const u32 *rkey_enc, u8 *iv, u8 *mac); 28 29 30 static int ccm_setkey(struct crypto_aead *tfm, const u8 *key, 31 unsigned int key_len) 32 { 33 struct sm4_ctx *ctx = crypto_aead_ctx(tfm); 34 35 if (key_len != SM4_KEY_SIZE) 36 return -EINVAL; 37 38 kernel_neon_begin(); 39 sm4_ce_expand_key(key, ctx->rkey_enc, ctx->rkey_dec, 40 crypto_sm4_fk, crypto_sm4_ck); 41 kernel_neon_end(); 42 43 return 0; 44 } 45 46 static int ccm_setauthsize(struct crypto_aead *tfm, unsigned int authsize) 47 { 48 if ((authsize & 1) || authsize < 4) 49 return -EINVAL; 50 return 0; 51 } 52 53 static int ccm_format_input(u8 info[], struct aead_request *req, 54 unsigned int msglen) 55 { 56 struct crypto_aead *aead = crypto_aead_reqtfm(req); 57 unsigned int l = req->iv[0] + 1; 58 unsigned int m; 59 __be32 len; 60 61 /* verify that CCM dimension 'L': 2 <= L <= 8 */ 62 if (l < 2 || l > 8) 63 return -EINVAL; 64 if (l < 4 && msglen >> (8 * l)) 65 return -EOVERFLOW; 66 67 memset(&req->iv[SM4_BLOCK_SIZE - l], 0, l); 68 69 memcpy(info, req->iv, SM4_BLOCK_SIZE); 70 71 m = crypto_aead_authsize(aead); 72 73 /* format flags field per RFC 3610/NIST 800-38C */ 74 *info |= ((m - 2) / 2) << 3; 75 if (req->assoclen) 76 *info |= (1 << 6); 77 78 /* 79 * format message length field, 80 * Linux uses a u32 type to represent msglen 81 */ 82 if (l >= 4) 83 l = 4; 84 85 len = cpu_to_be32(msglen); 86 memcpy(&info[SM4_BLOCK_SIZE - l], (u8 *)&len + 4 - l, l); 87 88 return 0; 89 } 90 91 static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[]) 92 { 93 struct crypto_aead *aead = crypto_aead_reqtfm(req); 94 struct sm4_ctx *ctx = crypto_aead_ctx(aead); 95 struct __packed { __be16 l; __be32 h; } aadlen; 96 u32 assoclen = req->assoclen; 97 struct scatter_walk walk; 98 unsigned int len; 99 100 if (assoclen < 0xff00) { 101 aadlen.l = cpu_to_be16(assoclen); 102 len = 2; 103 } else { 104 aadlen.l = cpu_to_be16(0xfffe); 105 put_unaligned_be32(assoclen, &aadlen.h); 106 len = 6; 107 } 108 109 sm4_ce_crypt_block(ctx->rkey_enc, mac, mac); 110 crypto_xor(mac, (const u8 *)&aadlen, len); 111 112 scatterwalk_start(&walk, req->src); 113 114 do { 115 u32 n = scatterwalk_clamp(&walk, assoclen); 116 u8 *p, *ptr; 117 118 if (!n) { 119 scatterwalk_start(&walk, sg_next(walk.sg)); 120 n = scatterwalk_clamp(&walk, assoclen); 121 } 122 123 p = ptr = scatterwalk_map(&walk); 124 assoclen -= n; 125 scatterwalk_advance(&walk, n); 126 127 while (n > 0) { 128 unsigned int l, nblocks; 129 130 if (len == SM4_BLOCK_SIZE) { 131 if (n < SM4_BLOCK_SIZE) { 132 sm4_ce_crypt_block(ctx->rkey_enc, 133 mac, mac); 134 135 len = 0; 136 } else { 137 nblocks = n / SM4_BLOCK_SIZE; 138 sm4_ce_cbcmac_update(ctx->rkey_enc, 139 mac, ptr, nblocks); 140 141 ptr += nblocks * SM4_BLOCK_SIZE; 142 n %= SM4_BLOCK_SIZE; 143 144 continue; 145 } 146 } 147 148 l = min(n, SM4_BLOCK_SIZE - len); 149 if (l) { 150 crypto_xor(mac + len, ptr, l); 151 len += l; 152 ptr += l; 153 n -= l; 154 } 155 } 156 157 scatterwalk_unmap(p); 158 scatterwalk_done(&walk, 0, assoclen); 159 } while (assoclen); 160 } 161 162 static int ccm_crypt(struct aead_request *req, struct skcipher_walk *walk, 163 u32 *rkey_enc, u8 mac[], 164 void (*sm4_ce_ccm_crypt)(const u32 *rkey_enc, u8 *dst, 165 const u8 *src, u8 *iv, 166 unsigned int nbytes, u8 *mac)) 167 { 168 u8 __aligned(8) ctr0[SM4_BLOCK_SIZE]; 169 int err = 0; 170 171 /* preserve the initial ctr0 for the TAG */ 172 memcpy(ctr0, walk->iv, SM4_BLOCK_SIZE); 173 crypto_inc(walk->iv, SM4_BLOCK_SIZE); 174 175 kernel_neon_begin(); 176 177 if (req->assoclen) 178 ccm_calculate_auth_mac(req, mac); 179 180 while (walk->nbytes && walk->nbytes != walk->total) { 181 unsigned int tail = walk->nbytes % SM4_BLOCK_SIZE; 182 183 sm4_ce_ccm_crypt(rkey_enc, walk->dst.virt.addr, 184 walk->src.virt.addr, walk->iv, 185 walk->nbytes - tail, mac); 186 187 kernel_neon_end(); 188 189 err = skcipher_walk_done(walk, tail); 190 191 kernel_neon_begin(); 192 } 193 194 if (walk->nbytes) { 195 sm4_ce_ccm_crypt(rkey_enc, walk->dst.virt.addr, 196 walk->src.virt.addr, walk->iv, 197 walk->nbytes, mac); 198 199 sm4_ce_ccm_final(rkey_enc, ctr0, mac); 200 201 kernel_neon_end(); 202 203 err = skcipher_walk_done(walk, 0); 204 } else { 205 sm4_ce_ccm_final(rkey_enc, ctr0, mac); 206 207 kernel_neon_end(); 208 } 209 210 return err; 211 } 212 213 static int ccm_encrypt(struct aead_request *req) 214 { 215 struct crypto_aead *aead = crypto_aead_reqtfm(req); 216 struct sm4_ctx *ctx = crypto_aead_ctx(aead); 217 u8 __aligned(8) mac[SM4_BLOCK_SIZE]; 218 struct skcipher_walk walk; 219 int err; 220 221 err = ccm_format_input(mac, req, req->cryptlen); 222 if (err) 223 return err; 224 225 err = skcipher_walk_aead_encrypt(&walk, req, false); 226 if (err) 227 return err; 228 229 err = ccm_crypt(req, &walk, ctx->rkey_enc, mac, sm4_ce_ccm_enc); 230 if (err) 231 return err; 232 233 /* copy authtag to end of dst */ 234 scatterwalk_map_and_copy(mac, req->dst, req->assoclen + req->cryptlen, 235 crypto_aead_authsize(aead), 1); 236 237 return 0; 238 } 239 240 static int ccm_decrypt(struct aead_request *req) 241 { 242 struct crypto_aead *aead = crypto_aead_reqtfm(req); 243 unsigned int authsize = crypto_aead_authsize(aead); 244 struct sm4_ctx *ctx = crypto_aead_ctx(aead); 245 u8 __aligned(8) mac[SM4_BLOCK_SIZE]; 246 u8 authtag[SM4_BLOCK_SIZE]; 247 struct skcipher_walk walk; 248 int err; 249 250 err = ccm_format_input(mac, req, req->cryptlen - authsize); 251 if (err) 252 return err; 253 254 err = skcipher_walk_aead_decrypt(&walk, req, false); 255 if (err) 256 return err; 257 258 err = ccm_crypt(req, &walk, ctx->rkey_enc, mac, sm4_ce_ccm_dec); 259 if (err) 260 return err; 261 262 /* compare calculated auth tag with the stored one */ 263 scatterwalk_map_and_copy(authtag, req->src, 264 req->assoclen + req->cryptlen - authsize, 265 authsize, 0); 266 267 if (crypto_memneq(authtag, mac, authsize)) 268 return -EBADMSG; 269 270 return 0; 271 } 272 273 static struct aead_alg sm4_ccm_alg = { 274 .base = { 275 .cra_name = "ccm(sm4)", 276 .cra_driver_name = "ccm-sm4-ce", 277 .cra_priority = 400, 278 .cra_blocksize = 1, 279 .cra_ctxsize = sizeof(struct sm4_ctx), 280 .cra_module = THIS_MODULE, 281 }, 282 .ivsize = SM4_BLOCK_SIZE, 283 .chunksize = SM4_BLOCK_SIZE, 284 .maxauthsize = SM4_BLOCK_SIZE, 285 .setkey = ccm_setkey, 286 .setauthsize = ccm_setauthsize, 287 .encrypt = ccm_encrypt, 288 .decrypt = ccm_decrypt, 289 }; 290 291 static int __init sm4_ce_ccm_init(void) 292 { 293 return crypto_register_aead(&sm4_ccm_alg); 294 } 295 296 static void __exit sm4_ce_ccm_exit(void) 297 { 298 crypto_unregister_aead(&sm4_ccm_alg); 299 } 300 301 module_cpu_feature_match(SM4, sm4_ce_ccm_init); 302 module_exit(sm4_ce_ccm_exit); 303 304 MODULE_DESCRIPTION("Synchronous SM4 in CCM mode using ARMv8 Crypto Extensions"); 305 MODULE_ALIAS_CRYPTO("ccm(sm4)"); 306 MODULE_AUTHOR("Tianjia Zhang <tianjia.zhang@linux.alibaba.com>"); 307 MODULE_LICENSE("GPL v2"); 308