1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * SM4-GCM 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/simd.h> 15 #include <crypto/b128ops.h> 16 #include <crypto/scatterwalk.h> 17 #include <crypto/internal/aead.h> 18 #include <crypto/internal/skcipher.h> 19 #include <crypto/sm4.h> 20 #include "sm4-ce.h" 21 22 asmlinkage void sm4_ce_pmull_ghash_setup(const u32 *rkey_enc, u8 *ghash_table); 23 asmlinkage void pmull_ghash_update(const u8 *ghash_table, u8 *ghash, 24 const u8 *src, unsigned int nblocks); 25 asmlinkage void sm4_ce_pmull_gcm_enc(const u32 *rkey_enc, u8 *dst, 26 const u8 *src, u8 *iv, 27 unsigned int nbytes, u8 *ghash, 28 const u8 *ghash_table, const u8 *lengths); 29 asmlinkage void sm4_ce_pmull_gcm_dec(const u32 *rkey_enc, u8 *dst, 30 const u8 *src, u8 *iv, 31 unsigned int nbytes, u8 *ghash, 32 const u8 *ghash_table, const u8 *lengths); 33 34 #define GHASH_BLOCK_SIZE 16 35 #define GCM_IV_SIZE 12 36 37 struct sm4_gcm_ctx { 38 struct sm4_ctx key; 39 u8 ghash_table[16 * 4]; 40 }; 41 42 43 static int gcm_setkey(struct crypto_aead *tfm, const u8 *key, 44 unsigned int key_len) 45 { 46 struct sm4_gcm_ctx *ctx = crypto_aead_ctx(tfm); 47 48 if (key_len != SM4_KEY_SIZE) 49 return -EINVAL; 50 51 scoped_ksimd() { 52 sm4_ce_expand_key(key, ctx->key.rkey_enc, ctx->key.rkey_dec, 53 crypto_sm4_fk, crypto_sm4_ck); 54 sm4_ce_pmull_ghash_setup(ctx->key.rkey_enc, ctx->ghash_table); 55 } 56 return 0; 57 } 58 59 static int gcm_setauthsize(struct crypto_aead *tfm, unsigned int authsize) 60 { 61 switch (authsize) { 62 case 4: 63 case 8: 64 case 12 ... 16: 65 return 0; 66 default: 67 return -EINVAL; 68 } 69 } 70 71 static void gcm_calculate_auth_mac(struct aead_request *req, u8 ghash[]) 72 { 73 struct crypto_aead *aead = crypto_aead_reqtfm(req); 74 struct sm4_gcm_ctx *ctx = crypto_aead_ctx(aead); 75 u8 __aligned(8) buffer[GHASH_BLOCK_SIZE]; 76 u32 assoclen = req->assoclen; 77 struct scatter_walk walk; 78 unsigned int buflen = 0; 79 80 scatterwalk_start(&walk, req->src); 81 82 do { 83 unsigned int n, orig_n; 84 const u8 *p; 85 86 orig_n = scatterwalk_next(&walk, assoclen); 87 p = walk.addr; 88 n = orig_n; 89 90 if (n + buflen < GHASH_BLOCK_SIZE) { 91 memcpy(&buffer[buflen], p, n); 92 buflen += n; 93 } else { 94 unsigned int nblocks; 95 96 if (buflen) { 97 unsigned int l = GHASH_BLOCK_SIZE - buflen; 98 99 memcpy(&buffer[buflen], p, l); 100 p += l; 101 n -= l; 102 103 pmull_ghash_update(ctx->ghash_table, ghash, 104 buffer, 1); 105 } 106 107 nblocks = n / GHASH_BLOCK_SIZE; 108 if (nblocks) { 109 pmull_ghash_update(ctx->ghash_table, ghash, 110 p, nblocks); 111 p += nblocks * GHASH_BLOCK_SIZE; 112 } 113 114 buflen = n % GHASH_BLOCK_SIZE; 115 if (buflen) 116 memcpy(&buffer[0], p, buflen); 117 } 118 119 scatterwalk_done_src(&walk, orig_n); 120 assoclen -= orig_n; 121 } while (assoclen); 122 123 /* padding with '0' */ 124 if (buflen) { 125 memset(&buffer[buflen], 0, GHASH_BLOCK_SIZE - buflen); 126 pmull_ghash_update(ctx->ghash_table, ghash, buffer, 1); 127 } 128 } 129 130 static int gcm_crypt(struct aead_request *req, struct skcipher_walk *walk, 131 u8 ghash[], int err, 132 void (*sm4_ce_pmull_gcm_crypt)(const u32 *rkey_enc, 133 u8 *dst, const u8 *src, u8 *iv, 134 unsigned int nbytes, u8 *ghash, 135 const u8 *ghash_table, const u8 *lengths)) 136 { 137 struct crypto_aead *aead = crypto_aead_reqtfm(req); 138 struct sm4_gcm_ctx *ctx = crypto_aead_ctx(aead); 139 u8 __aligned(8) iv[SM4_BLOCK_SIZE]; 140 be128 __aligned(8) lengths; 141 142 memset(ghash, 0, SM4_BLOCK_SIZE); 143 144 lengths.a = cpu_to_be64(req->assoclen * 8); 145 lengths.b = cpu_to_be64(walk->total * 8); 146 147 memcpy(iv, req->iv, GCM_IV_SIZE); 148 put_unaligned_be32(2, iv + GCM_IV_SIZE); 149 150 scoped_ksimd() { 151 if (req->assoclen) 152 gcm_calculate_auth_mac(req, ghash); 153 154 do { 155 unsigned int tail = walk->nbytes % SM4_BLOCK_SIZE; 156 const u8 *src = walk->src.virt.addr; 157 u8 *dst = walk->dst.virt.addr; 158 const u8 *l = NULL; 159 160 if (walk->nbytes == walk->total) { 161 l = (const u8 *)&lengths; 162 tail = 0; 163 } 164 165 sm4_ce_pmull_gcm_crypt(ctx->key.rkey_enc, dst, src, iv, 166 walk->nbytes - tail, ghash, 167 ctx->ghash_table, l); 168 169 err = skcipher_walk_done(walk, tail); 170 } while (walk->nbytes); 171 } 172 return err; 173 } 174 175 static int gcm_encrypt(struct aead_request *req) 176 { 177 struct crypto_aead *aead = crypto_aead_reqtfm(req); 178 u8 __aligned(8) ghash[SM4_BLOCK_SIZE]; 179 struct skcipher_walk walk; 180 int err; 181 182 err = skcipher_walk_aead_encrypt(&walk, req, false); 183 err = gcm_crypt(req, &walk, ghash, err, sm4_ce_pmull_gcm_enc); 184 if (err) 185 return err; 186 187 /* copy authtag to end of dst */ 188 scatterwalk_map_and_copy(ghash, req->dst, req->assoclen + req->cryptlen, 189 crypto_aead_authsize(aead), 1); 190 191 return 0; 192 } 193 194 static int gcm_decrypt(struct aead_request *req) 195 { 196 struct crypto_aead *aead = crypto_aead_reqtfm(req); 197 unsigned int authsize = crypto_aead_authsize(aead); 198 u8 __aligned(8) ghash[SM4_BLOCK_SIZE]; 199 u8 authtag[SM4_BLOCK_SIZE]; 200 struct skcipher_walk walk; 201 int err; 202 203 err = skcipher_walk_aead_decrypt(&walk, req, false); 204 err = gcm_crypt(req, &walk, ghash, err, sm4_ce_pmull_gcm_dec); 205 if (err) 206 return err; 207 208 /* compare calculated auth tag with the stored one */ 209 scatterwalk_map_and_copy(authtag, req->src, 210 req->assoclen + req->cryptlen - authsize, 211 authsize, 0); 212 213 if (crypto_memneq(authtag, ghash, authsize)) 214 return -EBADMSG; 215 216 return 0; 217 } 218 219 static struct aead_alg sm4_gcm_alg = { 220 .base = { 221 .cra_name = "gcm(sm4)", 222 .cra_driver_name = "gcm-sm4-ce", 223 .cra_priority = 400, 224 .cra_blocksize = 1, 225 .cra_ctxsize = sizeof(struct sm4_gcm_ctx), 226 .cra_module = THIS_MODULE, 227 }, 228 .ivsize = GCM_IV_SIZE, 229 .chunksize = SM4_BLOCK_SIZE, 230 .maxauthsize = SM4_BLOCK_SIZE, 231 .setkey = gcm_setkey, 232 .setauthsize = gcm_setauthsize, 233 .encrypt = gcm_encrypt, 234 .decrypt = gcm_decrypt, 235 }; 236 237 static int __init sm4_ce_gcm_init(void) 238 { 239 if (!cpu_have_named_feature(PMULL)) 240 return -ENODEV; 241 242 return crypto_register_aead(&sm4_gcm_alg); 243 } 244 245 static void __exit sm4_ce_gcm_exit(void) 246 { 247 crypto_unregister_aead(&sm4_gcm_alg); 248 } 249 250 static const struct cpu_feature __maybe_unused sm4_ce_gcm_cpu_feature[] = { 251 { cpu_feature(PMULL) }, 252 {} 253 }; 254 MODULE_DEVICE_TABLE(cpu, sm4_ce_gcm_cpu_feature); 255 256 module_cpu_feature_match(SM4, sm4_ce_gcm_init); 257 module_exit(sm4_ce_gcm_exit); 258 259 MODULE_DESCRIPTION("Synchronous SM4 in GCM mode using ARMv8 Crypto Extensions"); 260 MODULE_ALIAS_CRYPTO("gcm(sm4)"); 261 MODULE_AUTHOR("Tianjia Zhang <tianjia.zhang@linux.alibaba.com>"); 262 MODULE_LICENSE("GPL v2"); 263