1 /* 2 * Cryptographic API. 3 * 4 * HMAC: Keyed-Hashing for Message Authentication (RFC2104). 5 * 6 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au> 7 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au> 8 * 9 * The HMAC implementation is derived from USAGI. 10 * Copyright (c) 2002 Kazunori Miyazawa <miyazawa@linux-ipv6.org> / USAGI 11 * 12 * This program is free software; you can redistribute it and/or modify it 13 * under the terms of the GNU General Public License as published by the Free 14 * Software Foundation; either version 2 of the License, or (at your option) 15 * any later version. 16 * 17 */ 18 19 #include <crypto/algapi.h> 20 #include <linux/err.h> 21 #include <linux/init.h> 22 #include <linux/kernel.h> 23 #include <linux/module.h> 24 #include <linux/scatterlist.h> 25 #include <linux/slab.h> 26 #include <linux/string.h> 27 28 struct hmac_ctx { 29 struct crypto_hash *child; 30 }; 31 32 static void hash_key(struct crypto_tfm *tfm, u8 *key, unsigned int keylen) 33 { 34 struct scatterlist tmp; 35 36 sg_set_buf(&tmp, key, keylen); 37 crypto_digest_digest(tfm, &tmp, 1, key); 38 } 39 40 int crypto_alloc_hmac_block(struct crypto_tfm *tfm) 41 { 42 int ret = 0; 43 44 BUG_ON(!crypto_tfm_alg_blocksize(tfm)); 45 46 tfm->crt_hash.hmac_block = kmalloc(crypto_tfm_alg_blocksize(tfm), 47 GFP_KERNEL); 48 if (tfm->crt_hash.hmac_block == NULL) 49 ret = -ENOMEM; 50 51 return ret; 52 53 } 54 55 void crypto_free_hmac_block(struct crypto_tfm *tfm) 56 { 57 kfree(tfm->crt_hash.hmac_block); 58 } 59 60 void crypto_hmac_init(struct crypto_tfm *tfm, u8 *key, unsigned int *keylen) 61 { 62 unsigned int i; 63 struct scatterlist tmp; 64 char *ipad = tfm->crt_hash.hmac_block; 65 66 if (*keylen > crypto_tfm_alg_blocksize(tfm)) { 67 hash_key(tfm, key, *keylen); 68 *keylen = crypto_tfm_alg_digestsize(tfm); 69 } 70 71 memset(ipad, 0, crypto_tfm_alg_blocksize(tfm)); 72 memcpy(ipad, key, *keylen); 73 74 for (i = 0; i < crypto_tfm_alg_blocksize(tfm); i++) 75 ipad[i] ^= 0x36; 76 77 sg_set_buf(&tmp, ipad, crypto_tfm_alg_blocksize(tfm)); 78 79 crypto_digest_init(tfm); 80 crypto_digest_update(tfm, &tmp, 1); 81 } 82 83 void crypto_hmac_update(struct crypto_tfm *tfm, 84 struct scatterlist *sg, unsigned int nsg) 85 { 86 crypto_digest_update(tfm, sg, nsg); 87 } 88 89 void crypto_hmac_final(struct crypto_tfm *tfm, u8 *key, 90 unsigned int *keylen, u8 *out) 91 { 92 unsigned int i; 93 struct scatterlist tmp; 94 char *opad = tfm->crt_hash.hmac_block; 95 96 if (*keylen > crypto_tfm_alg_blocksize(tfm)) { 97 hash_key(tfm, key, *keylen); 98 *keylen = crypto_tfm_alg_digestsize(tfm); 99 } 100 101 crypto_digest_final(tfm, out); 102 103 memset(opad, 0, crypto_tfm_alg_blocksize(tfm)); 104 memcpy(opad, key, *keylen); 105 106 for (i = 0; i < crypto_tfm_alg_blocksize(tfm); i++) 107 opad[i] ^= 0x5c; 108 109 sg_set_buf(&tmp, opad, crypto_tfm_alg_blocksize(tfm)); 110 111 crypto_digest_init(tfm); 112 crypto_digest_update(tfm, &tmp, 1); 113 114 sg_set_buf(&tmp, out, crypto_tfm_alg_digestsize(tfm)); 115 116 crypto_digest_update(tfm, &tmp, 1); 117 crypto_digest_final(tfm, out); 118 } 119 120 void crypto_hmac(struct crypto_tfm *tfm, u8 *key, unsigned int *keylen, 121 struct scatterlist *sg, unsigned int nsg, u8 *out) 122 { 123 crypto_hmac_init(tfm, key, keylen); 124 crypto_hmac_update(tfm, sg, nsg); 125 crypto_hmac_final(tfm, key, keylen, out); 126 } 127 128 EXPORT_SYMBOL_GPL(crypto_hmac_init); 129 EXPORT_SYMBOL_GPL(crypto_hmac_update); 130 EXPORT_SYMBOL_GPL(crypto_hmac_final); 131 EXPORT_SYMBOL_GPL(crypto_hmac); 132 133 static inline void *align_ptr(void *p, unsigned int align) 134 { 135 return (void *)ALIGN((unsigned long)p, align); 136 } 137 138 static inline struct hmac_ctx *hmac_ctx(struct crypto_hash *tfm) 139 { 140 return align_ptr(crypto_hash_ctx_aligned(tfm) + 141 crypto_hash_blocksize(tfm) * 2 + 142 crypto_hash_digestsize(tfm), sizeof(void *)); 143 } 144 145 static int hmac_setkey(struct crypto_hash *parent, 146 const u8 *inkey, unsigned int keylen) 147 { 148 int bs = crypto_hash_blocksize(parent); 149 int ds = crypto_hash_digestsize(parent); 150 char *ipad = crypto_hash_ctx_aligned(parent); 151 char *opad = ipad + bs; 152 char *digest = opad + bs; 153 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *)); 154 struct crypto_hash *tfm = ctx->child; 155 unsigned int i; 156 157 if (keylen > bs) { 158 struct hash_desc desc; 159 struct scatterlist tmp; 160 int err; 161 162 desc.tfm = tfm; 163 desc.flags = crypto_hash_get_flags(parent); 164 desc.flags &= CRYPTO_TFM_REQ_MAY_SLEEP; 165 sg_set_buf(&tmp, inkey, keylen); 166 167 err = crypto_hash_digest(&desc, &tmp, keylen, digest); 168 if (err) 169 return err; 170 171 inkey = digest; 172 keylen = ds; 173 } 174 175 memcpy(ipad, inkey, keylen); 176 memset(ipad + keylen, 0, bs - keylen); 177 memcpy(opad, ipad, bs); 178 179 for (i = 0; i < bs; i++) { 180 ipad[i] ^= 0x36; 181 opad[i] ^= 0x5c; 182 } 183 184 return 0; 185 } 186 187 static int hmac_init(struct hash_desc *pdesc) 188 { 189 struct crypto_hash *parent = pdesc->tfm; 190 int bs = crypto_hash_blocksize(parent); 191 int ds = crypto_hash_digestsize(parent); 192 char *ipad = crypto_hash_ctx_aligned(parent); 193 struct hmac_ctx *ctx = align_ptr(ipad + bs * 2 + ds, sizeof(void *)); 194 struct hash_desc desc; 195 struct scatterlist tmp; 196 197 desc.tfm = ctx->child; 198 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 199 sg_set_buf(&tmp, ipad, bs); 200 201 return unlikely(crypto_hash_init(&desc)) ?: 202 crypto_hash_update(&desc, &tmp, 1); 203 } 204 205 static int hmac_update(struct hash_desc *pdesc, 206 struct scatterlist *sg, unsigned int nbytes) 207 { 208 struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm); 209 struct hash_desc desc; 210 211 desc.tfm = ctx->child; 212 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 213 214 return crypto_hash_update(&desc, sg, nbytes); 215 } 216 217 static int hmac_final(struct hash_desc *pdesc, u8 *out) 218 { 219 struct crypto_hash *parent = pdesc->tfm; 220 int bs = crypto_hash_blocksize(parent); 221 int ds = crypto_hash_digestsize(parent); 222 char *opad = crypto_hash_ctx_aligned(parent) + bs; 223 char *digest = opad + bs; 224 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *)); 225 struct hash_desc desc; 226 struct scatterlist tmp; 227 228 desc.tfm = ctx->child; 229 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 230 sg_set_buf(&tmp, opad, bs + ds); 231 232 return unlikely(crypto_hash_final(&desc, digest)) ?: 233 crypto_hash_digest(&desc, &tmp, bs + ds, out); 234 } 235 236 static int hmac_digest(struct hash_desc *pdesc, struct scatterlist *sg, 237 unsigned int nbytes, u8 *out) 238 { 239 struct crypto_hash *parent = pdesc->tfm; 240 int bs = crypto_hash_blocksize(parent); 241 int ds = crypto_hash_digestsize(parent); 242 char *ipad = crypto_hash_ctx_aligned(parent); 243 char *opad = ipad + bs; 244 char *digest = opad + bs; 245 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *)); 246 struct hash_desc desc; 247 struct scatterlist sg1[2]; 248 struct scatterlist sg2[1]; 249 250 desc.tfm = ctx->child; 251 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 252 253 sg_set_buf(sg1, ipad, bs); 254 sg1[1].page = (void *)sg; 255 sg1[1].length = 0; 256 sg_set_buf(sg2, opad, bs + ds); 257 258 return unlikely(crypto_hash_digest(&desc, sg1, nbytes + bs, digest)) ?: 259 crypto_hash_digest(&desc, sg2, bs + ds, out); 260 } 261 262 static int hmac_init_tfm(struct crypto_tfm *tfm) 263 { 264 struct crypto_instance *inst = (void *)tfm->__crt_alg; 265 struct crypto_spawn *spawn = crypto_instance_ctx(inst); 266 struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm)); 267 268 tfm = crypto_spawn_tfm(spawn); 269 if (IS_ERR(tfm)) 270 return PTR_ERR(tfm); 271 272 ctx->child = crypto_hash_cast(tfm); 273 return 0; 274 } 275 276 static void hmac_exit_tfm(struct crypto_tfm *tfm) 277 { 278 struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm)); 279 crypto_free_hash(ctx->child); 280 } 281 282 static void hmac_free(struct crypto_instance *inst) 283 { 284 crypto_drop_spawn(crypto_instance_ctx(inst)); 285 kfree(inst); 286 } 287 288 static struct crypto_instance *hmac_alloc(void *param, unsigned int len) 289 { 290 struct crypto_instance *inst; 291 struct crypto_alg *alg; 292 293 alg = crypto_get_attr_alg(param, len, CRYPTO_ALG_TYPE_HASH, 294 CRYPTO_ALG_TYPE_HASH_MASK | CRYPTO_ALG_ASYNC); 295 if (IS_ERR(alg)) 296 return ERR_PTR(PTR_ERR(alg)); 297 298 inst = crypto_alloc_instance("hmac", alg); 299 if (IS_ERR(inst)) 300 goto out_put_alg; 301 302 inst->alg.cra_flags = CRYPTO_ALG_TYPE_HASH; 303 inst->alg.cra_priority = alg->cra_priority; 304 inst->alg.cra_blocksize = alg->cra_blocksize; 305 inst->alg.cra_alignmask = alg->cra_alignmask; 306 inst->alg.cra_type = &crypto_hash_type; 307 308 inst->alg.cra_hash.digestsize = 309 (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) == 310 CRYPTO_ALG_TYPE_HASH ? alg->cra_hash.digestsize : 311 alg->cra_digest.dia_digestsize; 312 313 inst->alg.cra_ctxsize = sizeof(struct hmac_ctx) + 314 ALIGN(inst->alg.cra_blocksize * 2 + 315 inst->alg.cra_hash.digestsize, 316 sizeof(void *)); 317 318 inst->alg.cra_init = hmac_init_tfm; 319 inst->alg.cra_exit = hmac_exit_tfm; 320 321 inst->alg.cra_hash.init = hmac_init; 322 inst->alg.cra_hash.update = hmac_update; 323 inst->alg.cra_hash.final = hmac_final; 324 inst->alg.cra_hash.digest = hmac_digest; 325 inst->alg.cra_hash.setkey = hmac_setkey; 326 327 out_put_alg: 328 crypto_mod_put(alg); 329 return inst; 330 } 331 332 static struct crypto_template hmac_tmpl = { 333 .name = "hmac", 334 .alloc = hmac_alloc, 335 .free = hmac_free, 336 .module = THIS_MODULE, 337 }; 338 339 static int __init hmac_module_init(void) 340 { 341 return crypto_register_template(&hmac_tmpl); 342 } 343 344 static void __exit hmac_module_exit(void) 345 { 346 crypto_unregister_template(&hmac_tmpl); 347 } 348 349 module_init(hmac_module_init); 350 module_exit(hmac_module_exit); 351 352 MODULE_LICENSE("GPL"); 353 MODULE_DESCRIPTION("HMAC hash algorithm"); 354