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 unsigned int n, orig_n; 116 const u8 *p; 117 118 orig_n = scatterwalk_next(&walk, assoclen); 119 p = walk.addr; 120 n = orig_n; 121 122 while (n > 0) { 123 unsigned int l, nblocks; 124 125 if (len == SM4_BLOCK_SIZE) { 126 if (n < SM4_BLOCK_SIZE) { 127 sm4_ce_crypt_block(ctx->rkey_enc, 128 mac, mac); 129 130 len = 0; 131 } else { 132 nblocks = n / SM4_BLOCK_SIZE; 133 sm4_ce_cbcmac_update(ctx->rkey_enc, 134 mac, p, nblocks); 135 136 p += nblocks * SM4_BLOCK_SIZE; 137 n %= SM4_BLOCK_SIZE; 138 139 continue; 140 } 141 } 142 143 l = min(n, SM4_BLOCK_SIZE - len); 144 if (l) { 145 crypto_xor(mac + len, p, l); 146 len += l; 147 p += l; 148 n -= l; 149 } 150 } 151 152 scatterwalk_done_src(&walk, orig_n); 153 assoclen -= orig_n; 154 } while (assoclen); 155 } 156 157 static int ccm_crypt(struct aead_request *req, struct skcipher_walk *walk, 158 u32 *rkey_enc, u8 mac[], 159 void (*sm4_ce_ccm_crypt)(const u32 *rkey_enc, u8 *dst, 160 const u8 *src, u8 *iv, 161 unsigned int nbytes, u8 *mac)) 162 { 163 u8 __aligned(8) ctr0[SM4_BLOCK_SIZE]; 164 int err = 0; 165 166 /* preserve the initial ctr0 for the TAG */ 167 memcpy(ctr0, walk->iv, SM4_BLOCK_SIZE); 168 crypto_inc(walk->iv, SM4_BLOCK_SIZE); 169 170 kernel_neon_begin(); 171 172 if (req->assoclen) 173 ccm_calculate_auth_mac(req, mac); 174 175 while (walk->nbytes && walk->nbytes != walk->total) { 176 unsigned int tail = walk->nbytes % SM4_BLOCK_SIZE; 177 178 sm4_ce_ccm_crypt(rkey_enc, walk->dst.virt.addr, 179 walk->src.virt.addr, walk->iv, 180 walk->nbytes - tail, mac); 181 182 kernel_neon_end(); 183 184 err = skcipher_walk_done(walk, tail); 185 186 kernel_neon_begin(); 187 } 188 189 if (walk->nbytes) { 190 sm4_ce_ccm_crypt(rkey_enc, walk->dst.virt.addr, 191 walk->src.virt.addr, walk->iv, 192 walk->nbytes, mac); 193 194 sm4_ce_ccm_final(rkey_enc, ctr0, mac); 195 196 kernel_neon_end(); 197 198 err = skcipher_walk_done(walk, 0); 199 } else { 200 sm4_ce_ccm_final(rkey_enc, ctr0, mac); 201 202 kernel_neon_end(); 203 } 204 205 return err; 206 } 207 208 static int ccm_encrypt(struct aead_request *req) 209 { 210 struct crypto_aead *aead = crypto_aead_reqtfm(req); 211 struct sm4_ctx *ctx = crypto_aead_ctx(aead); 212 u8 __aligned(8) mac[SM4_BLOCK_SIZE]; 213 struct skcipher_walk walk; 214 int err; 215 216 err = ccm_format_input(mac, req, req->cryptlen); 217 if (err) 218 return err; 219 220 err = skcipher_walk_aead_encrypt(&walk, req, false); 221 if (err) 222 return err; 223 224 err = ccm_crypt(req, &walk, ctx->rkey_enc, mac, sm4_ce_ccm_enc); 225 if (err) 226 return err; 227 228 /* copy authtag to end of dst */ 229 scatterwalk_map_and_copy(mac, req->dst, req->assoclen + req->cryptlen, 230 crypto_aead_authsize(aead), 1); 231 232 return 0; 233 } 234 235 static int ccm_decrypt(struct aead_request *req) 236 { 237 struct crypto_aead *aead = crypto_aead_reqtfm(req); 238 unsigned int authsize = crypto_aead_authsize(aead); 239 struct sm4_ctx *ctx = crypto_aead_ctx(aead); 240 u8 __aligned(8) mac[SM4_BLOCK_SIZE]; 241 u8 authtag[SM4_BLOCK_SIZE]; 242 struct skcipher_walk walk; 243 int err; 244 245 err = ccm_format_input(mac, req, req->cryptlen - authsize); 246 if (err) 247 return err; 248 249 err = skcipher_walk_aead_decrypt(&walk, req, false); 250 if (err) 251 return err; 252 253 err = ccm_crypt(req, &walk, ctx->rkey_enc, mac, sm4_ce_ccm_dec); 254 if (err) 255 return err; 256 257 /* compare calculated auth tag with the stored one */ 258 scatterwalk_map_and_copy(authtag, req->src, 259 req->assoclen + req->cryptlen - authsize, 260 authsize, 0); 261 262 if (crypto_memneq(authtag, mac, authsize)) 263 return -EBADMSG; 264 265 return 0; 266 } 267 268 static struct aead_alg sm4_ccm_alg = { 269 .base = { 270 .cra_name = "ccm(sm4)", 271 .cra_driver_name = "ccm-sm4-ce", 272 .cra_priority = 400, 273 .cra_blocksize = 1, 274 .cra_ctxsize = sizeof(struct sm4_ctx), 275 .cra_module = THIS_MODULE, 276 }, 277 .ivsize = SM4_BLOCK_SIZE, 278 .chunksize = SM4_BLOCK_SIZE, 279 .maxauthsize = SM4_BLOCK_SIZE, 280 .setkey = ccm_setkey, 281 .setauthsize = ccm_setauthsize, 282 .encrypt = ccm_encrypt, 283 .decrypt = ccm_decrypt, 284 }; 285 286 static int __init sm4_ce_ccm_init(void) 287 { 288 return crypto_register_aead(&sm4_ccm_alg); 289 } 290 291 static void __exit sm4_ce_ccm_exit(void) 292 { 293 crypto_unregister_aead(&sm4_ccm_alg); 294 } 295 296 module_cpu_feature_match(SM4, sm4_ce_ccm_init); 297 module_exit(sm4_ce_ccm_exit); 298 299 MODULE_DESCRIPTION("Synchronous SM4 in CCM mode using ARMv8 Crypto Extensions"); 300 MODULE_ALIAS_CRYPTO("ccm(sm4)"); 301 MODULE_AUTHOR("Tianjia Zhang <tianjia.zhang@linux.alibaba.com>"); 302 MODULE_LICENSE("GPL v2"); 303