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 static int hmac_setkey(struct crypto_shash *parent,
  45                        const u8 *inkey, unsigned int keylen)
  46 {
  47         int bs = crypto_shash_blocksize(parent);
  48         int ds = crypto_shash_digestsize(parent);
  49         int ss = crypto_shash_statesize(parent);
  50         char *ipad = crypto_shash_ctx_aligned(parent);
  51         char *opad = ipad + ss;
  52         struct hmac_ctx *ctx = align_ptr(opad + ss,
  53                                          crypto_tfm_ctx_alignment());
  54         struct crypto_shash *hash = ctx->hash;
  55         SHASH_DESC_ON_STACK(shash, hash);
  56         unsigned int i;
  57
  58         shash->tfm = hash;
  59         shash->flags = crypto_shash_get_flags(parent)
  60                 & CRYPTO_TFM_REQ_MAY_SLEEP;
  61
  62         if (keylen > bs) {
  63                 int err;
  64
  65                 err = crypto_shash_digest(shash, inkey, keylen, ipad);
  66                 if (err)
  67                         return err;
  68
  69                 keylen = ds;
  70         } else
  71                 memcpy(ipad, inkey, keylen);
  72
  73         memset(ipad + keylen, 0, bs - keylen);
  74         memcpy(opad, ipad, bs);
  75
  76         for (i = 0; i < bs; i++) {
  77                 ipad[i] ^= 0x36;
  78                 opad[i] ^= 0x5c;
  79         }
  80
  81         return crypto_shash_init(shash) ?:
  82                crypto_shash_update(shash, ipad, bs) ?:
  83                crypto_shash_export(shash, ipad) ?:
  84                crypto_shash_init(shash) ?:
  85                crypto_shash_update(shash, opad, bs) ?:
  86                crypto_shash_export(shash, opad);
  87 }
  88
  89 static int hmac_export(struct shash_desc *pdesc, void *out)
  90 {
  91         struct shash_desc *desc = shash_desc_ctx(pdesc);
  92
  93         desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
  94
  95         return crypto_shash_export(desc, out);
  96 }
  97
  98 static int hmac_import(struct shash_desc *pdesc, const void *in)
  99 {
 100         struct shash_desc *desc = shash_desc_ctx(pdesc);
 101         struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm);
 102
 103         desc->tfm = ctx->hash;
 104         desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
 105
 106         return crypto_shash_import(desc, in);
 107 }
 108
 109 static int hmac_init(struct shash_desc *pdesc)
 110 {
 111         return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm));
 112 }
 113
 114 static int hmac_update(struct shash_desc *pdesc,
 115                        const u8 *data, unsigned int nbytes)
 116 {
 117         struct shash_desc *desc = shash_desc_ctx(pdesc);
 118
 119         desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
 120
 121         return crypto_shash_update(desc, data, nbytes);
 122 }
 123
 124 static int hmac_final(struct shash_desc *pdesc, u8 *out)
 125 {
 126         struct crypto_shash *parent = pdesc->tfm;
 127         int ds = crypto_shash_digestsize(parent);
 128         int ss = crypto_shash_statesize(parent);
 129         char *opad = crypto_shash_ctx_aligned(parent) + ss;
 130         struct shash_desc *desc = shash_desc_ctx(pdesc);
 131
 132         desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
 133
 134         return crypto_shash_final(desc, out) ?:
 135                crypto_shash_import(desc, opad) ?:
 136                crypto_shash_finup(desc, out, ds, out);
 137 }
 138
 139 static int hmac_finup(struct shash_desc *pdesc, const u8 *data,
 140                       unsigned int nbytes, u8 *out)
 141 {
 142
 143         struct crypto_shash *parent = pdesc->tfm;
 144         int ds = crypto_shash_digestsize(parent);
 145         int ss = crypto_shash_statesize(parent);
 146         char *opad = crypto_shash_ctx_aligned(parent) + ss;
 147         struct shash_desc *desc = shash_desc_ctx(pdesc);
 148
 149         desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
 150
 151         return crypto_shash_finup(desc, data, nbytes, out) ?:
 152                crypto_shash_import(desc, opad) ?:
 153                crypto_shash_finup(desc, out, ds, out);
 154 }
 155
 156 static int hmac_init_tfm(struct crypto_tfm *tfm)
 157 {
 158         struct crypto_shash *parent = __crypto_shash_cast(tfm);
 159         struct crypto_shash *hash;
 160         struct crypto_instance *inst = (void *)tfm->__crt_alg;
 161         struct crypto_shash_spawn *spawn = crypto_instance_ctx(inst);
 162         struct hmac_ctx *ctx = hmac_ctx(parent);
 163
 164         hash = crypto_spawn_shash(spawn);
 165         if (IS_ERR(hash))
 166                 return PTR_ERR(hash);
 167
 168         parent->descsize = sizeof(struct shash_desc) +
 169                            crypto_shash_descsize(hash);
 170
 171         ctx->hash = hash;
 172         return 0;
 173 }
 174
 175 static void hmac_exit_tfm(struct crypto_tfm *tfm)
 176 {
 177         struct hmac_ctx *ctx = hmac_ctx(__crypto_shash_cast(tfm));
 178         crypto_free_shash(ctx->hash);
 179 }
 180
 181 static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
 182 {
 183         struct shash_instance *inst;
 184         struct crypto_alg *alg;
 185         struct shash_alg *salg;
 186         int err;
 187         int ds;
 188         int ss;
 189
 190         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
 191         if (err)
 192                 return err;
 193
 194         salg = shash_attr_alg(tb[1], 0, 0);
 195         if (IS_ERR(salg))
 196                 return PTR_ERR(salg);
 197         alg = &salg->base;
 198
 199         /* The underlying hash algorithm must be unkeyed */
 200         err = -EINVAL;
 201         if (crypto_shash_alg_has_setkey(salg))
 202                 goto out_put_alg;
 203
 204         ds = salg->digestsize;
 205         ss = salg->statesize;
 206         if (ds > alg->cra_blocksize ||
 207             ss < alg->cra_blocksize)
 208                 goto out_put_alg;
 209
 210         inst = shash_alloc_instance("hmac", alg);
 211         err = PTR_ERR(inst);
 212         if (IS_ERR(inst))
 213                 goto out_put_alg;
 214
 215         err = crypto_init_shash_spawn(shash_instance_ctx(inst), salg,
 216                                       shash_crypto_instance(inst));
 217         if (err)
 218                 goto out_free_inst;
 219
 220         inst->alg.base.cra_priority = alg->cra_priority;
 221         inst->alg.base.cra_blocksize = alg->cra_blocksize;
 222         inst->alg.base.cra_alignmask = alg->cra_alignmask;
 223
 224         ss = ALIGN(ss, alg->cra_alignmask + 1);
 225         inst->alg.digestsize = ds;
 226         inst->alg.statesize = ss;
 227
 228         inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) +
 229                                      ALIGN(ss * 2, crypto_tfm_ctx_alignment());
 230
 231         inst->alg.base.cra_init = hmac_init_tfm;
 232         inst->alg.base.cra_exit = hmac_exit_tfm;
 233
 234         inst->alg.init = hmac_init;
 235         inst->alg.update = hmac_update;
 236         inst->alg.final = hmac_final;
 237         inst->alg.finup = hmac_finup;
 238         inst->alg.export = hmac_export;
 239         inst->alg.import = hmac_import;
 240         inst->alg.setkey = hmac_setkey;
 241
 242         err = shash_register_instance(tmpl, inst);
 243         if (err) {
 244 out_free_inst:
 245                 shash_free_instance(shash_crypto_instance(inst));
 246         }
 247
 248 out_put_alg:
 249         crypto_mod_put(alg);
 250         return err;
 251 }
 252
 253 static struct crypto_template hmac_tmpl = {
 254         .name = "hmac",
 255         .create = hmac_create,
 256         .free = shash_free_instance,
 257         .module = THIS_MODULE,
 258 };
 259
 260 static int __init hmac_module_init(void)
 261 {
 262         return crypto_register_template(&hmac_tmpl);
 263 }
 264
 265 static void __exit hmac_module_exit(void)
 266 {
 267         crypto_unregister_template(&hmac_tmpl);
 268 }
 269
 270 module_init(hmac_module_init);
 271 module_exit(hmac_module_exit);
 272
 273 MODULE_LICENSE("GPL");
 274 MODULE_DESCRIPTION("HMAC hash algorithm");
 275 MODULE_ALIAS_CRYPTO("hmac");