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/hmac.h> 20 #include <crypto/internal/hash.h> 21 #include <crypto/scatterwalk.h> 22 #include <linux/err.h> 23 #include <linux/init.h> 24 #include <linux/kernel.h> 25 #include <linux/module.h> 26 #include <linux/scatterlist.h> 27 #include <linux/string.h> 28 29 struct hmac_ctx { 30 struct crypto_shash *hash; 31 }; 32 33 static inline void *align_ptr(void *p, unsigned int align) 34 { 35 return (void *)ALIGN((unsigned long)p, align); 36 } 37 38 static inline struct hmac_ctx *hmac_ctx(struct crypto_shash *tfm) 39 { 40 return align_ptr(crypto_shash_ctx_aligned(tfm) + 41 crypto_shash_statesize(tfm) * 2, 42 crypto_tfm_ctx_alignment()); 43 } 44 45 static int hmac_setkey(struct crypto_shash *parent, 46 const u8 *inkey, unsigned int keylen) 47 { 48 int bs = crypto_shash_blocksize(parent); 49 int ds = crypto_shash_digestsize(parent); 50 int ss = crypto_shash_statesize(parent); 51 char *ipad = crypto_shash_ctx_aligned(parent); 52 char *opad = ipad + ss; 53 struct hmac_ctx *ctx = align_ptr(opad + ss, 54 crypto_tfm_ctx_alignment()); 55 struct crypto_shash *hash = ctx->hash; 56 SHASH_DESC_ON_STACK(shash, hash); 57 unsigned int i; 58 59 shash->tfm = hash; 60 61 if (keylen > bs) { 62 int err; 63 64 err = crypto_shash_digest(shash, inkey, keylen, ipad); 65 if (err) 66 return err; 67 68 keylen = ds; 69 } else 70 memcpy(ipad, inkey, keylen); 71 72 memset(ipad + keylen, 0, bs - keylen); 73 memcpy(opad, ipad, bs); 74 75 for (i = 0; i < bs; i++) { 76 ipad[i] ^= HMAC_IPAD_VALUE; 77 opad[i] ^= HMAC_OPAD_VALUE; 78 } 79 80 return crypto_shash_init(shash) ?: 81 crypto_shash_update(shash, ipad, bs) ?: 82 crypto_shash_export(shash, ipad) ?: 83 crypto_shash_init(shash) ?: 84 crypto_shash_update(shash, opad, bs) ?: 85 crypto_shash_export(shash, opad); 86 } 87 88 static int hmac_export(struct shash_desc *pdesc, void *out) 89 { 90 struct shash_desc *desc = shash_desc_ctx(pdesc); 91 92 return crypto_shash_export(desc, out); 93 } 94 95 static int hmac_import(struct shash_desc *pdesc, const void *in) 96 { 97 struct shash_desc *desc = shash_desc_ctx(pdesc); 98 struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm); 99 100 desc->tfm = ctx->hash; 101 102 return crypto_shash_import(desc, in); 103 } 104 105 static int hmac_init(struct shash_desc *pdesc) 106 { 107 return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm)); 108 } 109 110 static int hmac_update(struct shash_desc *pdesc, 111 const u8 *data, unsigned int nbytes) 112 { 113 struct shash_desc *desc = shash_desc_ctx(pdesc); 114 115 return crypto_shash_update(desc, data, nbytes); 116 } 117 118 static int hmac_final(struct shash_desc *pdesc, u8 *out) 119 { 120 struct crypto_shash *parent = pdesc->tfm; 121 int ds = crypto_shash_digestsize(parent); 122 int ss = crypto_shash_statesize(parent); 123 char *opad = crypto_shash_ctx_aligned(parent) + ss; 124 struct shash_desc *desc = shash_desc_ctx(pdesc); 125 126 return crypto_shash_final(desc, out) ?: 127 crypto_shash_import(desc, opad) ?: 128 crypto_shash_finup(desc, out, ds, out); 129 } 130 131 static int hmac_finup(struct shash_desc *pdesc, const u8 *data, 132 unsigned int nbytes, u8 *out) 133 { 134 135 struct crypto_shash *parent = pdesc->tfm; 136 int ds = crypto_shash_digestsize(parent); 137 int ss = crypto_shash_statesize(parent); 138 char *opad = crypto_shash_ctx_aligned(parent) + ss; 139 struct shash_desc *desc = shash_desc_ctx(pdesc); 140 141 return crypto_shash_finup(desc, data, nbytes, out) ?: 142 crypto_shash_import(desc, opad) ?: 143 crypto_shash_finup(desc, out, ds, out); 144 } 145 146 static int hmac_init_tfm(struct crypto_tfm *tfm) 147 { 148 struct crypto_shash *parent = __crypto_shash_cast(tfm); 149 struct crypto_shash *hash; 150 struct crypto_instance *inst = (void *)tfm->__crt_alg; 151 struct crypto_shash_spawn *spawn = crypto_instance_ctx(inst); 152 struct hmac_ctx *ctx = hmac_ctx(parent); 153 154 hash = crypto_spawn_shash(spawn); 155 if (IS_ERR(hash)) 156 return PTR_ERR(hash); 157 158 parent->descsize = sizeof(struct shash_desc) + 159 crypto_shash_descsize(hash); 160 if (WARN_ON(parent->descsize > HASH_MAX_DESCSIZE)) 161 return -EINVAL; 162 163 ctx->hash = hash; 164 return 0; 165 } 166 167 static void hmac_exit_tfm(struct crypto_tfm *tfm) 168 { 169 struct hmac_ctx *ctx = hmac_ctx(__crypto_shash_cast(tfm)); 170 crypto_free_shash(ctx->hash); 171 } 172 173 static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb) 174 { 175 struct shash_instance *inst; 176 struct crypto_alg *alg; 177 struct shash_alg *salg; 178 int err; 179 int ds; 180 int ss; 181 182 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH); 183 if (err) 184 return err; 185 186 salg = shash_attr_alg(tb[1], 0, 0); 187 if (IS_ERR(salg)) 188 return PTR_ERR(salg); 189 alg = &salg->base; 190 191 /* The underlying hash algorithm must be unkeyed */ 192 err = -EINVAL; 193 if (crypto_shash_alg_has_setkey(salg)) 194 goto out_put_alg; 195 196 ds = salg->digestsize; 197 ss = salg->statesize; 198 if (ds > alg->cra_blocksize || 199 ss < alg->cra_blocksize) 200 goto out_put_alg; 201 202 inst = shash_alloc_instance("hmac", alg); 203 err = PTR_ERR(inst); 204 if (IS_ERR(inst)) 205 goto out_put_alg; 206 207 err = crypto_init_shash_spawn(shash_instance_ctx(inst), salg, 208 shash_crypto_instance(inst)); 209 if (err) 210 goto out_free_inst; 211 212 inst->alg.base.cra_priority = alg->cra_priority; 213 inst->alg.base.cra_blocksize = alg->cra_blocksize; 214 inst->alg.base.cra_alignmask = alg->cra_alignmask; 215 216 ss = ALIGN(ss, alg->cra_alignmask + 1); 217 inst->alg.digestsize = ds; 218 inst->alg.statesize = ss; 219 220 inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) + 221 ALIGN(ss * 2, crypto_tfm_ctx_alignment()); 222 223 inst->alg.base.cra_init = hmac_init_tfm; 224 inst->alg.base.cra_exit = hmac_exit_tfm; 225 226 inst->alg.init = hmac_init; 227 inst->alg.update = hmac_update; 228 inst->alg.final = hmac_final; 229 inst->alg.finup = hmac_finup; 230 inst->alg.export = hmac_export; 231 inst->alg.import = hmac_import; 232 inst->alg.setkey = hmac_setkey; 233 234 err = shash_register_instance(tmpl, inst); 235 if (err) { 236 out_free_inst: 237 shash_free_instance(shash_crypto_instance(inst)); 238 } 239 240 out_put_alg: 241 crypto_mod_put(alg); 242 return err; 243 } 244 245 static struct crypto_template hmac_tmpl = { 246 .name = "hmac", 247 .create = hmac_create, 248 .free = shash_free_instance, 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