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/internal/hash.h> 20 #include <crypto/scatterwalk.h> 21 #include <linux/err.h> 22 #include <linux/init.h> 23 #include <linux/kernel.h> 24 #include <linux/module.h> 25 #include <linux/scatterlist.h> 26 #include <linux/string.h> 27 28 struct hmac_ctx { 29 struct crypto_shash *hash; 30 }; 31 32 static inline void *align_ptr(void *p, unsigned int align) 33 { 34 return (void *)ALIGN((unsigned long)p, align); 35 } 36 37 static inline struct hmac_ctx *hmac_ctx(struct crypto_shash *tfm) 38 { 39 return align_ptr(crypto_shash_ctx_aligned(tfm) + 40 crypto_shash_statesize(tfm) * 2, 41 crypto_tfm_ctx_alignment()); 42 } 43 44 static int hmac_setkey(struct crypto_shash *parent, 45 const u8 *inkey, unsigned int keylen) 46 { 47 int bs = crypto_shash_blocksize(parent); 48 int ds = crypto_shash_digestsize(parent); 49 int ss = crypto_shash_statesize(parent); 50 char *ipad = crypto_shash_ctx_aligned(parent); 51 char *opad = ipad + ss; 52 struct hmac_ctx *ctx = align_ptr(opad + ss, 53 crypto_tfm_ctx_alignment()); 54 struct crypto_shash *hash = ctx->hash; 55 SHASH_DESC_ON_STACK(shash, hash); 56 unsigned int i; 57 58 shash->tfm = hash; 59 shash->flags = crypto_shash_get_flags(parent) 60 & CRYPTO_TFM_REQ_MAY_SLEEP; 61 62 if (keylen > bs) { 63 int err; 64 65 err = crypto_shash_digest(shash, inkey, keylen, ipad); 66 if (err) 67 return err; 68 69 keylen = ds; 70 } else 71 memcpy(ipad, inkey, keylen); 72 73 memset(ipad + keylen, 0, bs - keylen); 74 memcpy(opad, ipad, bs); 75 76 for (i = 0; i < bs; i++) { 77 ipad[i] ^= 0x36; 78 opad[i] ^= 0x5c; 79 } 80 81 return crypto_shash_init(shash) ?: 82 crypto_shash_update(shash, ipad, bs) ?: 83 crypto_shash_export(shash, ipad) ?: 84 crypto_shash_init(shash) ?: 85 crypto_shash_update(shash, opad, bs) ?: 86 crypto_shash_export(shash, opad); 87 } 88 89 static int hmac_export(struct shash_desc *pdesc, void *out) 90 { 91 struct shash_desc *desc = shash_desc_ctx(pdesc); 92 93 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 94 95 return crypto_shash_export(desc, out); 96 } 97 98 static int hmac_import(struct shash_desc *pdesc, const void *in) 99 { 100 struct shash_desc *desc = shash_desc_ctx(pdesc); 101 struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm); 102 103 desc->tfm = ctx->hash; 104 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 105 106 return crypto_shash_import(desc, in); 107 } 108 109 static int hmac_init(struct shash_desc *pdesc) 110 { 111 return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm)); 112 } 113 114 static int hmac_update(struct shash_desc *pdesc, 115 const u8 *data, unsigned int nbytes) 116 { 117 struct shash_desc *desc = shash_desc_ctx(pdesc); 118 119 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 120 121 return crypto_shash_update(desc, data, nbytes); 122 } 123 124 static int hmac_final(struct shash_desc *pdesc, u8 *out) 125 { 126 struct crypto_shash *parent = pdesc->tfm; 127 int ds = crypto_shash_digestsize(parent); 128 int ss = crypto_shash_statesize(parent); 129 char *opad = crypto_shash_ctx_aligned(parent) + ss; 130 struct shash_desc *desc = shash_desc_ctx(pdesc); 131 132 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 133 134 return crypto_shash_final(desc, out) ?: 135 crypto_shash_import(desc, opad) ?: 136 crypto_shash_finup(desc, out, ds, out); 137 } 138 139 static int hmac_finup(struct shash_desc *pdesc, const u8 *data, 140 unsigned int nbytes, u8 *out) 141 { 142 143 struct crypto_shash *parent = pdesc->tfm; 144 int ds = crypto_shash_digestsize(parent); 145 int ss = crypto_shash_statesize(parent); 146 char *opad = crypto_shash_ctx_aligned(parent) + ss; 147 struct shash_desc *desc = shash_desc_ctx(pdesc); 148 149 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 150 151 return crypto_shash_finup(desc, data, nbytes, out) ?: 152 crypto_shash_import(desc, opad) ?: 153 crypto_shash_finup(desc, out, ds, out); 154 } 155 156 static int hmac_init_tfm(struct crypto_tfm *tfm) 157 { 158 struct crypto_shash *parent = __crypto_shash_cast(tfm); 159 struct crypto_shash *hash; 160 struct crypto_instance *inst = (void *)tfm->__crt_alg; 161 struct crypto_shash_spawn *spawn = crypto_instance_ctx(inst); 162 struct hmac_ctx *ctx = hmac_ctx(parent); 163 164 hash = crypto_spawn_shash(spawn); 165 if (IS_ERR(hash)) 166 return PTR_ERR(hash); 167 168 parent->descsize = sizeof(struct shash_desc) + 169 crypto_shash_descsize(hash); 170 171 ctx->hash = hash; 172 return 0; 173 } 174 175 static void hmac_exit_tfm(struct crypto_tfm *tfm) 176 { 177 struct hmac_ctx *ctx = hmac_ctx(__crypto_shash_cast(tfm)); 178 crypto_free_shash(ctx->hash); 179 } 180 181 static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb) 182 { 183 struct shash_instance *inst; 184 struct crypto_alg *alg; 185 struct shash_alg *salg; 186 int err; 187 int ds; 188 int ss; 189 190 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH); 191 if (err) 192 return err; 193 194 salg = shash_attr_alg(tb[1], 0, 0); 195 if (IS_ERR(salg)) 196 return PTR_ERR(salg); 197 198 err = -EINVAL; 199 ds = salg->digestsize; 200 ss = salg->statesize; 201 alg = &salg->base; 202 if (ds > alg->cra_blocksize || 203 ss < alg->cra_blocksize) 204 goto out_put_alg; 205 206 inst = shash_alloc_instance("hmac", alg); 207 err = PTR_ERR(inst); 208 if (IS_ERR(inst)) 209 goto out_put_alg; 210 211 err = crypto_init_shash_spawn(shash_instance_ctx(inst), salg, 212 shash_crypto_instance(inst)); 213 if (err) 214 goto out_free_inst; 215 216 inst->alg.base.cra_priority = alg->cra_priority; 217 inst->alg.base.cra_blocksize = alg->cra_blocksize; 218 inst->alg.base.cra_alignmask = alg->cra_alignmask; 219 220 ss = ALIGN(ss, alg->cra_alignmask + 1); 221 inst->alg.digestsize = ds; 222 inst->alg.statesize = ss; 223 224 inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) + 225 ALIGN(ss * 2, crypto_tfm_ctx_alignment()); 226 227 inst->alg.base.cra_init = hmac_init_tfm; 228 inst->alg.base.cra_exit = hmac_exit_tfm; 229 230 inst->alg.init = hmac_init; 231 inst->alg.update = hmac_update; 232 inst->alg.final = hmac_final; 233 inst->alg.finup = hmac_finup; 234 inst->alg.export = hmac_export; 235 inst->alg.import = hmac_import; 236 inst->alg.setkey = hmac_setkey; 237 238 err = shash_register_instance(tmpl, inst); 239 if (err) { 240 out_free_inst: 241 shash_free_instance(shash_crypto_instance(inst)); 242 } 243 244 out_put_alg: 245 crypto_mod_put(alg); 246 return err; 247 } 248 249 static struct crypto_template hmac_tmpl = { 250 .name = "hmac", 251 .create = hmac_create, 252 .free = shash_free_instance, 253 .module = THIS_MODULE, 254 }; 255 256 static int __init hmac_module_init(void) 257 { 258 return crypto_register_template(&hmac_tmpl); 259 } 260 261 static void __exit hmac_module_exit(void) 262 { 263 crypto_unregister_template(&hmac_tmpl); 264 } 265 266 module_init(hmac_module_init); 267 module_exit(hmac_module_exit); 268 269 MODULE_LICENSE("GPL"); 270 MODULE_DESCRIPTION("HMAC hash algorithm"); 271 MODULE_ALIAS_CRYPTO("hmac"); 272