crypto/hmac.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Cryptographic API.
   4  *
   5  * HMAC: Keyed-Hashing for Message Authentication (RFC2104).
   6  *
   7  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
   8  * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
   9  *
  10  * The HMAC implementation is derived from USAGI.
  11  * Copyright (c) 2002 Kazunori Miyazawa <miyazawa@linux-ipv6.org> / USAGI
  12  */
  13
  14 #include <crypto/hmac.h>
  15 #include <crypto/internal/hash.h>
  16 #include <crypto/scatterwalk.h>
  17 #include <linux/err.h>
  18 #include <linux/fips.h>
  19 #include <linux/init.h>
  20 #include <linux/kernel.h>
  21 #include <linux/module.h>
  22 #include <linux/scatterlist.h>
  23 #include <linux/string.h>
  24
  25 struct hmac_ctx {
  26         struct crypto_shash *hash;
  27         /* Contains 'u8 ipad[statesize];', then 'u8 opad[statesize];' */
  28         u8 pads[];
  29 };
  30
  31 static int hmac_setkey(struct crypto_shash *parent,
  32                        const u8 *inkey, unsigned int keylen)
  33 {
  34         int bs = crypto_shash_blocksize(parent);
  35         int ds = crypto_shash_digestsize(parent);
  36         int ss = crypto_shash_statesize(parent);
  37         struct hmac_ctx *tctx = crypto_shash_ctx(parent);
  38         struct crypto_shash *hash = tctx->hash;
  39         u8 *ipad = &tctx->pads[0];
  40         u8 *opad = &tctx->pads[ss];
  41         SHASH_DESC_ON_STACK(shash, hash);
  42         unsigned int i;
  43
  44         if (fips_enabled && (keylen < 112 / 8))
  45                 return -EINVAL;
  46
  47         shash->tfm = hash;
  48
  49         if (keylen > bs) {
  50                 int err;
  51
  52                 err = crypto_shash_digest(shash, inkey, keylen, ipad);
  53                 if (err)
  54                         return err;
  55
  56                 keylen = ds;
  57         } else
  58                 memcpy(ipad, inkey, keylen);
  59
  60         memset(ipad + keylen, 0, bs - keylen);
  61         memcpy(opad, ipad, bs);
  62
  63         for (i = 0; i < bs; i++) {
  64                 ipad[i] ^= HMAC_IPAD_VALUE;
  65                 opad[i] ^= HMAC_OPAD_VALUE;
  66         }
  67
  68         return crypto_shash_init(shash) ?:
  69                crypto_shash_update(shash, ipad, bs) ?:
  70                crypto_shash_export(shash, ipad) ?:
  71                crypto_shash_init(shash) ?:
  72                crypto_shash_update(shash, opad, bs) ?:
  73                crypto_shash_export(shash, opad);
  74 }
  75
  76 static int hmac_export(struct shash_desc *pdesc, void *out)
  77 {
  78         struct shash_desc *desc = shash_desc_ctx(pdesc);
  79
  80         return crypto_shash_export(desc, out);
  81 }
  82
  83 static int hmac_import(struct shash_desc *pdesc, const void *in)
  84 {
  85         struct shash_desc *desc = shash_desc_ctx(pdesc);
  86         const struct hmac_ctx *tctx = crypto_shash_ctx(pdesc->tfm);
  87
  88         desc->tfm = tctx->hash;
  89
  90         return crypto_shash_import(desc, in);
  91 }
  92
  93 static int hmac_init(struct shash_desc *pdesc)
  94 {
  95         const struct hmac_ctx *tctx = crypto_shash_ctx(pdesc->tfm);
  96
  97         return hmac_import(pdesc, &tctx->pads[0]);
  98 }
  99
 100 static int hmac_update(struct shash_desc *pdesc,
 101                        const u8 *data, unsigned int nbytes)
 102 {
 103         struct shash_desc *desc = shash_desc_ctx(pdesc);
 104
 105         return crypto_shash_update(desc, data, nbytes);
 106 }
 107
 108 static int hmac_final(struct shash_desc *pdesc, u8 *out)
 109 {
 110         struct crypto_shash *parent = pdesc->tfm;
 111         int ds = crypto_shash_digestsize(parent);
 112         int ss = crypto_shash_statesize(parent);
 113         const struct hmac_ctx *tctx = crypto_shash_ctx(parent);
 114         const u8 *opad = &tctx->pads[ss];
 115         struct shash_desc *desc = shash_desc_ctx(pdesc);
 116
 117         return crypto_shash_final(desc, out) ?:
 118                crypto_shash_import(desc, opad) ?:
 119                crypto_shash_finup(desc, out, ds, out);
 120 }
 121
 122 static int hmac_finup(struct shash_desc *pdesc, const u8 *data,
 123                       unsigned int nbytes, u8 *out)
 124 {
 125
 126         struct crypto_shash *parent = pdesc->tfm;
 127         int ds = crypto_shash_digestsize(parent);
 128         int ss = crypto_shash_statesize(parent);
 129         const struct hmac_ctx *tctx = crypto_shash_ctx(parent);
 130         const u8 *opad = &tctx->pads[ss];
 131         struct shash_desc *desc = shash_desc_ctx(pdesc);
 132
 133         return crypto_shash_finup(desc, data, nbytes, out) ?:
 134                crypto_shash_import(desc, opad) ?:
 135                crypto_shash_finup(desc, out, ds, out);
 136 }
 137
 138 static int hmac_init_tfm(struct crypto_shash *parent)
 139 {
 140         struct crypto_shash *hash;
 141         struct shash_instance *inst = shash_alg_instance(parent);
 142         struct crypto_shash_spawn *spawn = shash_instance_ctx(inst);
 143         struct hmac_ctx *tctx = crypto_shash_ctx(parent);
 144
 145         hash = crypto_spawn_shash(spawn);
 146         if (IS_ERR(hash))
 147                 return PTR_ERR(hash);
 148
 149         parent->descsize = sizeof(struct shash_desc) +
 150                            crypto_shash_descsize(hash);
 151
 152         tctx->hash = hash;
 153         return 0;
 154 }
 155
 156 static int hmac_clone_tfm(struct crypto_shash *dst, struct crypto_shash *src)
 157 {
 158         struct hmac_ctx *sctx = crypto_shash_ctx(src);
 159         struct hmac_ctx *dctx = crypto_shash_ctx(dst);
 160         struct crypto_shash *hash;
 161
 162         hash = crypto_clone_shash(sctx->hash);
 163         if (IS_ERR(hash))
 164                 return PTR_ERR(hash);
 165
 166         dctx->hash = hash;
 167         return 0;
 168 }
 169
 170 static void hmac_exit_tfm(struct crypto_shash *parent)
 171 {
 172         struct hmac_ctx *tctx = crypto_shash_ctx(parent);
 173
 174         crypto_free_shash(tctx->hash);
 175 }
 176
 177 static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
 178 {
 179         struct shash_instance *inst;
 180         struct crypto_shash_spawn *spawn;
 181         struct crypto_alg *alg;
 182         struct shash_alg *salg;
 183         u32 mask;
 184         int err;
 185         int ds;
 186         int ss;
 187
 188         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH, &mask);
 189         if (err)
 190                 return err;
 191
 192         inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
 193         if (!inst)
 194                 return -ENOMEM;
 195         spawn = shash_instance_ctx(inst);
 196
 197         err = crypto_grab_shash(spawn, shash_crypto_instance(inst),
 198                                 crypto_attr_alg_name(tb[1]), 0, mask);
 199         if (err)
 200                 goto err_free_inst;
 201         salg = crypto_spawn_shash_alg(spawn);
 202         alg = &salg->base;
 203
 204         /* The underlying hash algorithm must not require a key */
 205         err = -EINVAL;
 206         if (crypto_shash_alg_needs_key(salg))
 207                 goto err_free_inst;
 208
 209         ds = salg->digestsize;
 210         ss = salg->statesize;
 211         if (ds > alg->cra_blocksize ||
 212             ss < alg->cra_blocksize)
 213                 goto err_free_inst;
 214
 215         err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg);
 216         if (err)
 217                 goto err_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_ctxsize = sizeof(struct hmac_ctx) + (ss * 2);
 222
 223         inst->alg.digestsize = ds;
 224         inst->alg.statesize = ss;
 225         inst->alg.init = hmac_init;
 226         inst->alg.update = hmac_update;
 227         inst->alg.final = hmac_final;
 228         inst->alg.finup = hmac_finup;
 229         inst->alg.export = hmac_export;
 230         inst->alg.import = hmac_import;
 231         inst->alg.setkey = hmac_setkey;
 232         inst->alg.init_tfm = hmac_init_tfm;
 233         inst->alg.clone_tfm = hmac_clone_tfm;
 234         inst->alg.exit_tfm = hmac_exit_tfm;
 235
 236         inst->free = shash_free_singlespawn_instance;
 237
 238         err = shash_register_instance(tmpl, inst);
 239         if (err) {
 240 err_free_inst:
 241                 shash_free_singlespawn_instance(inst);
 242         }
 243         return err;
 244 }
 245
 246 static struct crypto_template hmac_tmpl = {
 247         .name = "hmac",
 248         .create = hmac_create,
 249         .module = THIS_MODULE,
 250 };
 251
 252 static int __init hmac_module_init(void)
 253 {
 254         return crypto_register_template(&hmac_tmpl);
 255 }
 256
 257 static void __exit hmac_module_exit(void)
 258 {
 259         crypto_unregister_template(&hmac_tmpl);
 260 }
 261
 262 subsys_initcall(hmac_module_init);
 263 module_exit(hmac_module_exit);
 264
 265 MODULE_LICENSE("GPL");
 266 MODULE_DESCRIPTION("HMAC hash algorithm");
 267 MODULE_ALIAS_CRYPTO("hmac");