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 28struct hmac_ctx { 29 struct crypto_shash *hash; 30}; 31 32static inline void *align_ptr(void *p, unsigned int align) 33{ 34 return (void *)ALIGN((unsigned long)p, align); 35} 36 37static 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 44static 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 struct { 56 struct shash_desc shash; 57 char ctx[crypto_shash_descsize(hash)]; 58 } desc; 59 unsigned int i; 60 61 desc.shash.tfm = hash; 62 desc.shash.flags = crypto_shash_get_flags(parent) & 63 CRYPTO_TFM_REQ_MAY_SLEEP; 64 65 if (keylen > bs) { 66 int err; 67 68 err = crypto_shash_digest(&desc.shash, inkey, keylen, ipad); 69 if (err) 70 return err; 71 72 keylen = ds; 73 } else 74 memcpy(ipad, inkey, keylen); 75 76 memset(ipad + keylen, 0, bs - keylen); 77 memcpy(opad, ipad, bs); 78 79 for (i = 0; i < bs; i++) { 80 ipad[i] ^= 0x36; 81 opad[i] ^= 0x5c; 82 } 83 84 return crypto_shash_init(&desc.shash) ?: 85 crypto_shash_update(&desc.shash, ipad, bs) ?: 86 crypto_shash_export(&desc.shash, ipad) ?: 87 crypto_shash_init(&desc.shash) ?: 88 crypto_shash_update(&desc.shash, opad, bs) ?: 89 crypto_shash_export(&desc.shash, opad); 90} 91 92static int hmac_export(struct shash_desc *pdesc, void *out) 93{ 94 struct shash_desc *desc = shash_desc_ctx(pdesc); 95 96 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 97 98 return crypto_shash_export(desc, out); 99} 100 101static int hmac_import(struct shash_desc *pdesc, const void *in) 102{ 103 struct shash_desc *desc = shash_desc_ctx(pdesc); 104 struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm); 105 106 desc->tfm = ctx->hash; 107 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 108 109 return crypto_shash_import(desc, in); 110} 111 112static int hmac_init(struct shash_desc *pdesc) 113{ 114 return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm)); 115} 116 117static int hmac_update(struct shash_desc *pdesc, 118 const u8 *data, unsigned int nbytes) 119{ 120 struct shash_desc *desc = shash_desc_ctx(pdesc); 121 122 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 123 124 return crypto_shash_update(desc, data, nbytes); 125} 126 127static int hmac_final(struct shash_desc *pdesc, u8 *out) 128{ 129 struct crypto_shash *parent = pdesc->tfm; 130 int ds = crypto_shash_digestsize(parent); 131 int ss = crypto_shash_statesize(parent); 132 char *opad = crypto_shash_ctx_aligned(parent) + ss; 133 struct shash_desc *desc = shash_desc_ctx(pdesc); 134 135 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 136 137 return crypto_shash_final(desc, out) ?: 138 crypto_shash_import(desc, opad) ?: 139 crypto_shash_finup(desc, out, ds, out); 140} 141 142static int hmac_finup(struct shash_desc *pdesc, const u8 *data, 143 unsigned int nbytes, u8 *out) 144{ 145 146 struct crypto_shash *parent = pdesc->tfm; 147 int ds = crypto_shash_digestsize(parent); 148 int ss = crypto_shash_statesize(parent); 149 char *opad = crypto_shash_ctx_aligned(parent) + ss; 150 struct shash_desc *desc = shash_desc_ctx(pdesc); 151 152 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 153 154 return crypto_shash_finup(desc, data, nbytes, out) ?: 155 crypto_shash_import(desc, opad) ?: 156 crypto_shash_finup(desc, out, ds, out); 157} 158 159static int hmac_init_tfm(struct crypto_tfm *tfm) 160{ 161 struct crypto_shash *parent = __crypto_shash_cast(tfm); 162 struct crypto_shash *hash; 163 struct crypto_instance *inst = (void *)tfm->__crt_alg; 164 struct crypto_shash_spawn *spawn = crypto_instance_ctx(inst); 165 struct hmac_ctx *ctx = hmac_ctx(parent); 166 167 hash = crypto_spawn_shash(spawn); 168 if (IS_ERR(hash)) 169 return PTR_ERR(hash); 170 171 parent->descsize = sizeof(struct shash_desc) + 172 crypto_shash_descsize(hash); 173 174 ctx->hash = hash; 175 return 0; 176} 177 178static void hmac_exit_tfm(struct crypto_tfm *tfm) 179{ 180 struct hmac_ctx *ctx = hmac_ctx(__crypto_shash_cast(tfm)); 181 crypto_free_shash(ctx->hash); 182} 183 184static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb) 185{ 186 struct shash_instance *inst; 187 struct crypto_alg *alg; 188 struct shash_alg *salg; 189 int err; 190 int ds; 191 int ss; 192 193 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH); 194 if (err) 195 return err; 196 197 salg = shash_attr_alg(tb[1], 0, 0); 198 if (IS_ERR(salg)) 199 return PTR_ERR(salg); 200 201 err = -EINVAL; 202 ds = salg->digestsize; 203 ss = salg->statesize; 204 alg = &salg->base; 205 if (ds > alg->cra_blocksize || 206 ss < alg->cra_blocksize) 207 goto out_put_alg; 208 209 inst = shash_alloc_instance("hmac", alg); 210 err = PTR_ERR(inst); 211 if (IS_ERR(inst)) 212 goto out_put_alg; 213 214 err = crypto_init_shash_spawn(shash_instance_ctx(inst), salg, 215 shash_crypto_instance(inst)); 216 if (err) 217 goto out_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_alignmask = alg->cra_alignmask; 222 223 ss = ALIGN(ss, alg->cra_alignmask + 1); 224 inst->alg.digestsize = ds; 225 inst->alg.statesize = ss; 226 227 inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) + 228 ALIGN(ss * 2, crypto_tfm_ctx_alignment()); 229 230 inst->alg.base.cra_init = hmac_init_tfm; 231 inst->alg.base.cra_exit = hmac_exit_tfm; 232 233 inst->alg.init = hmac_init; 234 inst->alg.update = hmac_update; 235 inst->alg.final = hmac_final; 236 inst->alg.finup = hmac_finup; 237 inst->alg.export = hmac_export; 238 inst->alg.import = hmac_import; 239 inst->alg.setkey = hmac_setkey; 240 241 err = shash_register_instance(tmpl, inst); 242 if (err) { 243out_free_inst: 244 shash_free_instance(shash_crypto_instance(inst)); 245 } 246 247out_put_alg: 248 crypto_mod_put(alg); 249 return err; 250} 251 252static struct crypto_template hmac_tmpl = { 253 .name = "hmac", 254 .create = hmac_create, 255 .free = shash_free_instance, 256 .module = THIS_MODULE, 257}; 258 259static int __init hmac_module_init(void) 260{ 261 return crypto_register_template(&hmac_tmpl); 262} 263 264static void __exit hmac_module_exit(void) 265{ 266 crypto_unregister_template(&hmac_tmpl); 267} 268 269module_init(hmac_module_init); 270module_exit(hmac_module_exit); 271 272MODULE_LICENSE("GPL"); 273MODULE_DESCRIPTION("HMAC hash algorithm"); 274