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