crypto/hmac.c

   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/internal/hash.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/string.h>
  27
  28 struct hmac_ctx {
  29         struct crypto_shash *hash;
  30 };
  31
  32 static inline void *align_ptr(void *p, unsigned int align)
  33 {
  34         return (void *)ALIGN((unsigned long)p, align);
  35 }
  36
  37 static inline struct hmac_ctx *hmac_ctx(struct crypto_shash *tfm)
  38 {
  39         return align_ptr(crypto_shash_ctx_aligned(tfm) +
  40                          crypto_shash_statesize(tfm) * 2,
  41                          crypto_tfm_ctx_alignment());
  42 }
  43
  44 /* LCC does not understand VLA in structures */
  45 #if !defined CONFIG_MCST || !defined __LCC__
  46 static int hmac_setkey(struct crypto_shash *parent,
  47                        const u8 *inkey, unsigned int keylen)
  48 {
  49         int bs = crypto_shash_blocksize(parent);
  50         int ds = crypto_shash_digestsize(parent);
  51         int ss = crypto_shash_statesize(parent);
  52         char *ipad = crypto_shash_ctx_aligned(parent);
  53         char *opad = ipad + ss;
  54         struct hmac_ctx *ctx = align_ptr(opad + ss,
  55                                          crypto_tfm_ctx_alignment());
  56         struct crypto_shash *hash = ctx->hash;
  57         struct {
  58                 struct shash_desc shash;
  59                 char ctx[crypto_shash_descsize(hash)];
  60         } desc;
  61         unsigned int i;
  62
  63         desc.shash.tfm = hash;
  64         desc.shash.flags = crypto_shash_get_flags(parent) &
  65                             CRYPTO_TFM_REQ_MAY_SLEEP;
  66
  67         if (keylen > bs) {
  68                 int err;
  69
  70                 err = crypto_shash_digest(&desc.shash, inkey, keylen, ipad);
  71                 if (err)
  72                         return err;
  73
  74                 keylen = ds;
  75         } else
  76                 memcpy(ipad, inkey, keylen);
  77
  78         memset(ipad + keylen, 0, bs - keylen);
  79         memcpy(opad, ipad, bs);
  80
  81         for (i = 0; i < bs; i++) {
  82                 ipad[i] ^= 0x36;
  83                 opad[i] ^= 0x5c;
  84         }
  85
  86         return crypto_shash_init(&desc.shash) ?:
  87                crypto_shash_update(&desc.shash, ipad, bs) ?:
  88                crypto_shash_export(&desc.shash, ipad) ?:
  89                crypto_shash_init(&desc.shash) ?:
  90                crypto_shash_update(&desc.shash, opad, bs) ?:
  91                crypto_shash_export(&desc.shash, opad);
  92 }
  93 #else /* !defined CONFIG_MCST || !defined __LCC__ || __LCC__ != 118 */
  94 static int hmac_setkey(struct crypto_shash *parent,
  95                        const u8 *inkey, unsigned int keylen)
  96 {
  97         int bs = crypto_shash_blocksize(parent);
  98         int ds = crypto_shash_digestsize(parent);
  99         int ss = crypto_shash_statesize(parent);
 100         char *ipad = crypto_shash_ctx_aligned(parent);
 101         char *opad = ipad + ss;
 102         struct hmac_ctx *ctx = align_ptr(opad + ss,
 103                                          crypto_tfm_ctx_alignment());
 104         struct crypto_shash *hash = ctx->hash;
 105         struct shash_desc *desc;
 106         unsigned int i;
 107
 108         desc = __builtin_alloca(sizeof(*desc) + crypto_shash_descsize(hash));
 109
 110         desc->tfm = hash;
 111         desc->flags = crypto_shash_get_flags(parent) &
 112                             CRYPTO_TFM_REQ_MAY_SLEEP;
 113
 114         if (keylen > bs) {
 115                 int err;
 116
 117                 err = crypto_shash_digest(desc, inkey, keylen, ipad);
 118                 if (err)
 119                         return err;
 120
 121                 keylen = ds;
 122         } else
 123                 memcpy(ipad, inkey, keylen);
 124
 125         memset(ipad + keylen, 0, bs - keylen);
 126         memcpy(opad, ipad, bs);
 127
 128         for (i = 0; i < bs; i++) {
 129                 ipad[i] ^= 0x36;
 130                 opad[i] ^= 0x5c;
 131         }
 132
 133         return crypto_shash_init(desc) ?:
 134                crypto_shash_update(desc, ipad, bs) ?:
 135                crypto_shash_export(desc, ipad) ?:
 136                crypto_shash_init(desc) ?:
 137                crypto_shash_update(desc, opad, bs) ?:
 138                crypto_shash_export(desc, opad);
 139 }
 140 #endif /* !defined CONFIG_MCST || !defined __LCC__ || __LCC__ != 118 */
 141
 142 static int hmac_export(struct shash_desc *pdesc, void *out)
 143 {
 144         struct shash_desc *desc = shash_desc_ctx(pdesc);
 145
 146         desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
 147
 148         return crypto_shash_export(desc, out);
 149 }
 150
 151 static int hmac_import(struct shash_desc *pdesc, const void *in)
 152 {
 153         struct shash_desc *desc = shash_desc_ctx(pdesc);
 154         struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm);
 155
 156         desc->tfm = ctx->hash;
 157         desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
 158
 159         return crypto_shash_import(desc, in);
 160 }
 161
 162 static int hmac_init(struct shash_desc *pdesc)
 163 {
 164         return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm));
 165 }
 166
 167 static int hmac_update(struct shash_desc *pdesc,
 168                        const u8 *data, unsigned int nbytes)
 169 {
 170         struct shash_desc *desc = shash_desc_ctx(pdesc);
 171
 172         desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
 173
 174         return crypto_shash_update(desc, data, nbytes);
 175 }
 176
 177 static int hmac_final(struct shash_desc *pdesc, u8 *out)
 178 {
 179         struct crypto_shash *parent = pdesc->tfm;
 180         int ds = crypto_shash_digestsize(parent);
 181         int ss = crypto_shash_statesize(parent);
 182         char *opad = crypto_shash_ctx_aligned(parent) + ss;
 183         struct shash_desc *desc = shash_desc_ctx(pdesc);
 184
 185         desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
 186
 187         return crypto_shash_final(desc, out) ?:
 188                crypto_shash_import(desc, opad) ?:
 189                crypto_shash_finup(desc, out, ds, out);
 190 }
 191
 192 static int hmac_finup(struct shash_desc *pdesc, const u8 *data,
 193                       unsigned int nbytes, u8 *out)
 194 {
 195
 196         struct crypto_shash *parent = pdesc->tfm;
 197         int ds = crypto_shash_digestsize(parent);
 198         int ss = crypto_shash_statesize(parent);
 199         char *opad = crypto_shash_ctx_aligned(parent) + ss;
 200         struct shash_desc *desc = shash_desc_ctx(pdesc);
 201
 202         desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
 203
 204         return crypto_shash_finup(desc, data, nbytes, out) ?:
 205                crypto_shash_import(desc, opad) ?:
 206                crypto_shash_finup(desc, out, ds, out);
 207 }
 208
 209 static int hmac_init_tfm(struct crypto_tfm *tfm)
 210 {
 211         struct crypto_shash *parent = __crypto_shash_cast(tfm);
 212         struct crypto_shash *hash;
 213         struct crypto_instance *inst = (void *)tfm->__crt_alg;
 214         struct crypto_shash_spawn *spawn = crypto_instance_ctx(inst);
 215         struct hmac_ctx *ctx = hmac_ctx(parent);
 216
 217         hash = crypto_spawn_shash(spawn);
 218         if (IS_ERR(hash))
 219                 return PTR_ERR(hash);
 220
 221         parent->descsize = sizeof(struct shash_desc) +
 222                            crypto_shash_descsize(hash);
 223
 224         ctx->hash = hash;
 225         return 0;
 226 }
 227
 228 static void hmac_exit_tfm(struct crypto_tfm *tfm)
 229 {
 230         struct hmac_ctx *ctx = hmac_ctx(__crypto_shash_cast(tfm));
 231         crypto_free_shash(ctx->hash);
 232 }
 233
 234 static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
 235 {
 236         struct shash_instance *inst;
 237         struct crypto_alg *alg;
 238         struct shash_alg *salg;
 239         int err;
 240         int ds;
 241         int ss;
 242
 243         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
 244         if (err)
 245                 return err;
 246
 247         salg = shash_attr_alg(tb[1], 0, 0);
 248         if (IS_ERR(salg))
 249                 return PTR_ERR(salg);
 250
 251         err = -EINVAL;
 252         ds = salg->digestsize;
 253         ss = salg->statesize;
 254         alg = &salg->base;
 255         if (ds > alg->cra_blocksize ||
 256             ss < alg->cra_blocksize)
 257                 goto out_put_alg;
 258
 259         inst = shash_alloc_instance("hmac", alg);
 260         err = PTR_ERR(inst);
 261         if (IS_ERR(inst))
 262                 goto out_put_alg;
 263
 264         err = crypto_init_shash_spawn(shash_instance_ctx(inst), salg,
 265                                       shash_crypto_instance(inst));
 266         if (err)
 267                 goto out_free_inst;
 268
 269         inst->alg.base.cra_priority = alg->cra_priority;
 270         inst->alg.base.cra_blocksize = alg->cra_blocksize;
 271         inst->alg.base.cra_alignmask = alg->cra_alignmask;
 272
 273         ss = ALIGN(ss, alg->cra_alignmask + 1);
 274         inst->alg.digestsize = ds;
 275         inst->alg.statesize = ss;
 276
 277         inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) +
 278                                      ALIGN(ss * 2, crypto_tfm_ctx_alignment());
 279
 280         inst->alg.base.cra_init = hmac_init_tfm;
 281         inst->alg.base.cra_exit = hmac_exit_tfm;
 282
 283         inst->alg.init = hmac_init;
 284         inst->alg.update = hmac_update;
 285         inst->alg.final = hmac_final;
 286         inst->alg.finup = hmac_finup;
 287         inst->alg.export = hmac_export;
 288         inst->alg.import = hmac_import;
 289         inst->alg.setkey = hmac_setkey;
 290
 291         err = shash_register_instance(tmpl, inst);
 292         if (err) {
 293 out_free_inst:
 294                 shash_free_instance(shash_crypto_instance(inst));
 295         }
 296
 297 out_put_alg:
 298         crypto_mod_put(alg);
 299         return err;
 300 }
 301
 302 static struct crypto_template hmac_tmpl = {
 303         .name = "hmac",
 304         .create = hmac_create,
 305         .free = shash_free_instance,
 306         .module = THIS_MODULE,
 307 };
 308
 309 static int __init hmac_module_init(void)
 310 {
 311         return crypto_register_template(&hmac_tmpl);
 312 }
 313
 314 static void __exit hmac_module_exit(void)
 315 {
 316         crypto_unregister_template(&hmac_tmpl);
 317 }
 318
 319 module_init(hmac_module_init);
 320 module_exit(hmac_module_exit);
 321
 322 MODULE_LICENSE("GPL");
 323 MODULE_DESCRIPTION("HMAC hash algorithm");
 324 MODULE_ALIAS_CRYPTO("hmac");