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