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 };
  28
  29 static inline void *align_ptr(void *p, unsigned int align)
  30 {
  31         return (void *)ALIGN((unsigned long)p, align);
  32 }
  33
  34 static inline struct hmac_ctx *hmac_ctx(struct crypto_shash *tfm)
  35 {
  36         return align_ptr(crypto_shash_ctx_aligned(tfm) +
  37                          crypto_shash_statesize(tfm) * 2,
  38                          crypto_tfm_ctx_alignment());
  39 }
  40
  41 static int hmac_setkey(struct crypto_shash *parent,
  42                        const u8 *inkey, unsigned int keylen)
  43 {
  44         int bs = crypto_shash_blocksize(parent);
  45         int ds = crypto_shash_digestsize(parent);
  46         int ss = crypto_shash_statesize(parent);
  47         char *ipad = crypto_shash_ctx_aligned(parent);
  48         char *opad = ipad + ss;
  49         struct hmac_ctx *ctx = align_ptr(opad + ss,
  50                                          crypto_tfm_ctx_alignment());
  51         struct crypto_shash *hash = ctx->hash;
  52         SHASH_DESC_ON_STACK(shash, hash);
  53         unsigned int i;
  54
  55         if (fips_enabled && (keylen < 112 / 8))
  56                 return -EINVAL;
  57
  58         shash->tfm = hash;
  59
  60         if (keylen > bs) {
  61                 int err;
  62
  63                 err = crypto_shash_digest(shash, inkey, keylen, ipad);
  64                 if (err)
  65                         return err;
  66
  67                 keylen = ds;
  68         } else
  69                 memcpy(ipad, inkey, keylen);
  70
  71         memset(ipad + keylen, 0, bs - keylen);
  72         memcpy(opad, ipad, bs);
  73
  74         for (i = 0; i < bs; i++) {
  75                 ipad[i] ^= HMAC_IPAD_VALUE;
  76                 opad[i] ^= HMAC_OPAD_VALUE;
  77         }
  78
  79         return crypto_shash_init(shash) ?:
  80                crypto_shash_update(shash, ipad, bs) ?:
  81                crypto_shash_export(shash, ipad) ?:
  82                crypto_shash_init(shash) ?:
  83                crypto_shash_update(shash, opad, bs) ?:
  84                crypto_shash_export(shash, opad);
  85 }
  86
  87 static int hmac_export(struct shash_desc *pdesc, void *out)
  88 {
  89         struct shash_desc *desc = shash_desc_ctx(pdesc);
  90
  91         return crypto_shash_export(desc, out);
  92 }
  93
  94 static int hmac_import(struct shash_desc *pdesc, const void *in)
  95 {
  96         struct shash_desc *desc = shash_desc_ctx(pdesc);
  97         struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm);
  98
  99         desc->tfm = ctx->hash;
 100
 101         return crypto_shash_import(desc, in);
 102 }
 103
 104 static int hmac_init(struct shash_desc *pdesc)
 105 {
 106         return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm));
 107 }
 108
 109 static int hmac_update(struct shash_desc *pdesc,
 110                        const u8 *data, unsigned int nbytes)
 111 {
 112         struct shash_desc *desc = shash_desc_ctx(pdesc);
 113
 114         return crypto_shash_update(desc, data, nbytes);
 115 }
 116
 117 static int hmac_final(struct shash_desc *pdesc, u8 *out)
 118 {
 119         struct crypto_shash *parent = pdesc->tfm;
 120         int ds = crypto_shash_digestsize(parent);
 121         int ss = crypto_shash_statesize(parent);
 122         char *opad = crypto_shash_ctx_aligned(parent) + ss;
 123         struct shash_desc *desc = shash_desc_ctx(pdesc);
 124
 125         return crypto_shash_final(desc, out) ?:
 126                crypto_shash_import(desc, opad) ?:
 127                crypto_shash_finup(desc, out, ds, out);
 128 }
 129
 130 static int hmac_finup(struct shash_desc *pdesc, const u8 *data,
 131                       unsigned int nbytes, u8 *out)
 132 {
 133
 134         struct crypto_shash *parent = pdesc->tfm;
 135         int ds = crypto_shash_digestsize(parent);
 136         int ss = crypto_shash_statesize(parent);
 137         char *opad = crypto_shash_ctx_aligned(parent) + ss;
 138         struct shash_desc *desc = shash_desc_ctx(pdesc);
 139
 140         return crypto_shash_finup(desc, data, nbytes, out) ?:
 141                crypto_shash_import(desc, opad) ?:
 142                crypto_shash_finup(desc, out, ds, out);
 143 }
 144
 145 static int hmac_init_tfm(struct crypto_shash *parent)
 146 {
 147         struct crypto_shash *hash;
 148         struct shash_instance *inst = shash_alg_instance(parent);
 149         struct crypto_shash_spawn *spawn = shash_instance_ctx(inst);
 150         struct hmac_ctx *ctx = hmac_ctx(parent);
 151
 152         hash = crypto_spawn_shash(spawn);
 153         if (IS_ERR(hash))
 154                 return PTR_ERR(hash);
 155
 156         parent->descsize = sizeof(struct shash_desc) +
 157                            crypto_shash_descsize(hash);
 158
 159         ctx->hash = hash;
 160         return 0;
 161 }
 162
 163 static int hmac_clone_tfm(struct crypto_shash *dst, struct crypto_shash *src)
 164 {
 165         struct hmac_ctx *sctx = hmac_ctx(src);
 166         struct hmac_ctx *dctx = hmac_ctx(dst);
 167         struct crypto_shash *hash;
 168
 169         hash = crypto_clone_shash(sctx->hash);
 170         if (IS_ERR(hash))
 171                 return PTR_ERR(hash);
 172
 173         dctx->hash = hash;
 174         return 0;
 175 }
 176
 177 static void hmac_exit_tfm(struct crypto_shash *parent)
 178 {
 179         struct hmac_ctx *ctx = hmac_ctx(parent);
 180
 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_shash_spawn *spawn;
 188         struct crypto_alg *alg;
 189         struct shash_alg *salg;
 190         u32 mask;
 191         int err;
 192         int ds;
 193         int ss;
 194
 195         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH, &mask);
 196         if (err)
 197                 return err;
 198
 199         inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
 200         if (!inst)
 201                 return -ENOMEM;
 202         spawn = shash_instance_ctx(inst);
 203
 204         err = crypto_grab_shash(spawn, shash_crypto_instance(inst),
 205                                 crypto_attr_alg_name(tb[1]), 0, mask);
 206         if (err)
 207                 goto err_free_inst;
 208         salg = crypto_spawn_shash_alg(spawn);
 209         alg = &salg->base;
 210
 211         /* The underlying hash algorithm must not require a key */
 212         err = -EINVAL;
 213         if (crypto_shash_alg_needs_key(salg))
 214                 goto err_free_inst;
 215
 216         ds = salg->digestsize;
 217         ss = salg->statesize;
 218         if (ds > alg->cra_blocksize ||
 219             ss < alg->cra_blocksize)
 220                 goto err_free_inst;
 221
 222         err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg);
 223         if (err)
 224                 goto err_free_inst;
 225
 226         inst->alg.base.cra_priority = alg->cra_priority;
 227         inst->alg.base.cra_blocksize = alg->cra_blocksize;
 228         inst->alg.base.cra_alignmask = alg->cra_alignmask;
 229
 230         ss = ALIGN(ss, alg->cra_alignmask + 1);
 231         inst->alg.digestsize = ds;
 232         inst->alg.statesize = ss;
 233
 234         inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) +
 235                                      ALIGN(ss * 2, crypto_tfm_ctx_alignment());
 236
 237         inst->alg.init = hmac_init;
 238         inst->alg.update = hmac_update;
 239         inst->alg.final = hmac_final;
 240         inst->alg.finup = hmac_finup;
 241         inst->alg.export = hmac_export;
 242         inst->alg.import = hmac_import;
 243         inst->alg.setkey = hmac_setkey;
 244         inst->alg.init_tfm = hmac_init_tfm;
 245         inst->alg.clone_tfm = hmac_clone_tfm;
 246         inst->alg.exit_tfm = hmac_exit_tfm;
 247
 248         inst->free = shash_free_singlespawn_instance;
 249
 250         err = shash_register_instance(tmpl, inst);
 251         if (err) {
 252 err_free_inst:
 253                 shash_free_singlespawn_instance(inst);
 254         }
 255         return err;
 256 }
 257
 258 static struct crypto_template hmac_tmpl = {
 259         .name = "hmac",
 260         .create = hmac_create,
 261         .module = THIS_MODULE,
 262 };
 263
 264 static int __init hmac_module_init(void)
 265 {
 266         return crypto_register_template(&hmac_tmpl);
 267 }
 268
 269 static void __exit hmac_module_exit(void)
 270 {
 271         crypto_unregister_template(&hmac_tmpl);
 272 }
 273
 274 subsys_initcall(hmac_module_init);
 275 module_exit(hmac_module_exit);
 276
 277 MODULE_LICENSE("GPL");
 278 MODULE_DESCRIPTION("HMAC hash algorithm");
 279 MODULE_ALIAS_CRYPTO("hmac");