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"); 268