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 <crypto/scatterwalk.h> 21 #include <linux/err.h> 22 #include <linux/init.h> 23 #include <linux/kernel.h> 24 #include <linux/module.h> 25 #include <linux/scatterlist.h> 26 #include <linux/slab.h> 27 #include <linux/string.h> 28 29 struct hmac_ctx { 30 struct crypto_hash *child; 31 }; 32 33 static inline void *align_ptr(void *p, unsigned int align) 34 { 35 return (void *)ALIGN((unsigned long)p, align); 36 } 37 38 static inline struct hmac_ctx *hmac_ctx(struct crypto_hash *tfm) 39 { 40 return align_ptr(crypto_hash_ctx_aligned(tfm) + 41 crypto_hash_blocksize(tfm) * 2 + 42 crypto_hash_digestsize(tfm), sizeof(void *)); 43 } 44 45 static int hmac_setkey(struct crypto_hash *parent, 46 const u8 *inkey, unsigned int keylen) 47 { 48 int bs = crypto_hash_blocksize(parent); 49 int ds = crypto_hash_digestsize(parent); 50 char *ipad = crypto_hash_ctx_aligned(parent); 51 char *opad = ipad + bs; 52 char *digest = opad + bs; 53 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *)); 54 struct crypto_hash *tfm = ctx->child; 55 unsigned int i; 56 57 if (keylen > bs) { 58 struct hash_desc desc; 59 struct scatterlist tmp; 60 int tmplen; 61 int err; 62 63 desc.tfm = tfm; 64 desc.flags = crypto_hash_get_flags(parent); 65 desc.flags &= CRYPTO_TFM_REQ_MAY_SLEEP; 66 67 err = crypto_hash_init(&desc); 68 if (err) 69 return err; 70 71 tmplen = bs * 2 + ds; 72 sg_init_one(&tmp, ipad, tmplen); 73 74 for (; keylen > tmplen; inkey += tmplen, keylen -= tmplen) { 75 memcpy(ipad, inkey, tmplen); 76 err = crypto_hash_update(&desc, &tmp, tmplen); 77 if (err) 78 return err; 79 } 80 81 if (keylen) { 82 memcpy(ipad, inkey, keylen); 83 err = crypto_hash_update(&desc, &tmp, keylen); 84 if (err) 85 return err; 86 } 87 88 err = crypto_hash_final(&desc, digest); 89 if (err) 90 return err; 91 92 inkey = digest; 93 keylen = ds; 94 } 95 96 memcpy(ipad, inkey, keylen); 97 memset(ipad + keylen, 0, bs - keylen); 98 memcpy(opad, ipad, bs); 99 100 for (i = 0; i < bs; i++) { 101 ipad[i] ^= 0x36; 102 opad[i] ^= 0x5c; 103 } 104 105 return 0; 106 } 107 108 static int hmac_init(struct hash_desc *pdesc) 109 { 110 struct crypto_hash *parent = pdesc->tfm; 111 int bs = crypto_hash_blocksize(parent); 112 int ds = crypto_hash_digestsize(parent); 113 char *ipad = crypto_hash_ctx_aligned(parent); 114 struct hmac_ctx *ctx = align_ptr(ipad + bs * 2 + ds, sizeof(void *)); 115 struct hash_desc desc; 116 struct scatterlist tmp; 117 int err; 118 119 desc.tfm = ctx->child; 120 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 121 sg_init_one(&tmp, ipad, bs); 122 123 err = crypto_hash_init(&desc); 124 if (unlikely(err)) 125 return err; 126 127 return crypto_hash_update(&desc, &tmp, bs); 128 } 129 130 static int hmac_update(struct hash_desc *pdesc, 131 struct scatterlist *sg, unsigned int nbytes) 132 { 133 struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm); 134 struct hash_desc desc; 135 136 desc.tfm = ctx->child; 137 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 138 139 return crypto_hash_update(&desc, sg, nbytes); 140 } 141 142 static int hmac_final(struct hash_desc *pdesc, u8 *out) 143 { 144 struct crypto_hash *parent = pdesc->tfm; 145 int bs = crypto_hash_blocksize(parent); 146 int ds = crypto_hash_digestsize(parent); 147 char *opad = crypto_hash_ctx_aligned(parent) + bs; 148 char *digest = opad + bs; 149 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *)); 150 struct hash_desc desc; 151 struct scatterlist tmp; 152 int err; 153 154 desc.tfm = ctx->child; 155 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 156 sg_init_one(&tmp, opad, bs + ds); 157 158 err = crypto_hash_final(&desc, digest); 159 if (unlikely(err)) 160 return err; 161 162 return crypto_hash_digest(&desc, &tmp, bs + ds, out); 163 } 164 165 static int hmac_digest(struct hash_desc *pdesc, struct scatterlist *sg, 166 unsigned int nbytes, u8 *out) 167 { 168 struct crypto_hash *parent = pdesc->tfm; 169 int bs = crypto_hash_blocksize(parent); 170 int ds = crypto_hash_digestsize(parent); 171 char *ipad = crypto_hash_ctx_aligned(parent); 172 char *opad = ipad + bs; 173 char *digest = opad + bs; 174 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *)); 175 struct hash_desc desc; 176 struct scatterlist sg1[2]; 177 struct scatterlist sg2[1]; 178 int err; 179 180 desc.tfm = ctx->child; 181 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 182 183 sg_init_table(sg1, 2); 184 sg_set_buf(sg1, ipad, bs); 185 scatterwalk_sg_chain(sg1, 2, sg); 186 187 sg_init_table(sg2, 1); 188 sg_set_buf(sg2, opad, bs + ds); 189 190 err = crypto_hash_digest(&desc, sg1, nbytes + bs, digest); 191 if (unlikely(err)) 192 return err; 193 194 return crypto_hash_digest(&desc, sg2, bs + ds, out); 195 } 196 197 static int hmac_init_tfm(struct crypto_tfm *tfm) 198 { 199 struct crypto_hash *hash; 200 struct crypto_instance *inst = (void *)tfm->__crt_alg; 201 struct crypto_spawn *spawn = crypto_instance_ctx(inst); 202 struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm)); 203 204 hash = crypto_spawn_hash(spawn); 205 if (IS_ERR(hash)) 206 return PTR_ERR(hash); 207 208 ctx->child = hash; 209 return 0; 210 } 211 212 static void hmac_exit_tfm(struct crypto_tfm *tfm) 213 { 214 struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm)); 215 crypto_free_hash(ctx->child); 216 } 217 218 static void hmac_free(struct crypto_instance *inst) 219 { 220 crypto_drop_spawn(crypto_instance_ctx(inst)); 221 kfree(inst); 222 } 223 224 static struct crypto_instance *hmac_alloc(struct rtattr **tb) 225 { 226 struct crypto_instance *inst; 227 struct crypto_alg *alg; 228 int err; 229 int ds; 230 231 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_HASH); 232 if (err) 233 return ERR_PTR(err); 234 235 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_HASH, 236 CRYPTO_ALG_TYPE_HASH_MASK); 237 if (IS_ERR(alg)) 238 return ERR_CAST(alg); 239 240 inst = ERR_PTR(-EINVAL); 241 ds = (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) == 242 CRYPTO_ALG_TYPE_HASH ? alg->cra_hash.digestsize : 243 alg->cra_digest.dia_digestsize; 244 if (ds > alg->cra_blocksize) 245 goto out_put_alg; 246 247 inst = crypto_alloc_instance("hmac", alg); 248 if (IS_ERR(inst)) 249 goto out_put_alg; 250 251 inst->alg.cra_flags = CRYPTO_ALG_TYPE_HASH; 252 inst->alg.cra_priority = alg->cra_priority; 253 inst->alg.cra_blocksize = alg->cra_blocksize; 254 inst->alg.cra_alignmask = alg->cra_alignmask; 255 inst->alg.cra_type = &crypto_hash_type; 256 257 inst->alg.cra_hash.digestsize = ds; 258 259 inst->alg.cra_ctxsize = sizeof(struct hmac_ctx) + 260 ALIGN(inst->alg.cra_blocksize * 2 + ds, 261 sizeof(void *)); 262 263 inst->alg.cra_init = hmac_init_tfm; 264 inst->alg.cra_exit = hmac_exit_tfm; 265 266 inst->alg.cra_hash.init = hmac_init; 267 inst->alg.cra_hash.update = hmac_update; 268 inst->alg.cra_hash.final = hmac_final; 269 inst->alg.cra_hash.digest = hmac_digest; 270 inst->alg.cra_hash.setkey = hmac_setkey; 271 272 out_put_alg: 273 crypto_mod_put(alg); 274 return inst; 275 } 276 277 static struct crypto_template hmac_tmpl = { 278 .name = "hmac", 279 .alloc = hmac_alloc, 280 .free = hmac_free, 281 .module = THIS_MODULE, 282 }; 283 284 static int __init hmac_module_init(void) 285 { 286 return crypto_register_template(&hmac_tmpl); 287 } 288 289 static void __exit hmac_module_exit(void) 290 { 291 crypto_unregister_template(&hmac_tmpl); 292 } 293 294 module_init(hmac_module_init); 295 module_exit(hmac_module_exit); 296 297 MODULE_LICENSE("GPL"); 298 MODULE_DESCRIPTION("HMAC hash algorithm"); 299