arch/arm64/crypto/sm4-ce-ccm-glue.c

   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");