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/slab.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 struct { 57 struct shash_desc shash; 58 char ctx[crypto_shash_descsize(hash)]; 59 } desc; 60 unsigned int i; 61 62 desc.shash.tfm = hash; 63 desc.shash.flags = crypto_shash_get_flags(parent) & 64 CRYPTO_TFM_REQ_MAY_SLEEP; 65 66 if (keylen > bs) { 67 int err; 68 69 err = crypto_shash_digest(&desc.shash, inkey, keylen, ipad); 70 if (err) 71 return err; 72 73 keylen = ds; 74 } else 75 memcpy(ipad, inkey, keylen); 76 77 memset(ipad + keylen, 0, bs - keylen); 78 memcpy(opad, ipad, bs); 79 80 for (i = 0; i < bs; i++) { 81 ipad[i] ^= 0x36; 82 opad[i] ^= 0x5c; 83 } 84 85 return crypto_shash_init(&desc.shash) ?: 86 crypto_shash_update(&desc.shash, ipad, bs) ?: 87 crypto_shash_export(&desc.shash, ipad) ?: 88 crypto_shash_init(&desc.shash) ?: 89 crypto_shash_update(&desc.shash, opad, bs) ?: 90 crypto_shash_export(&desc.shash, opad); 91 } 92 93 static int hmac_export(struct shash_desc *pdesc, void *out) 94 { 95 struct shash_desc *desc = shash_desc_ctx(pdesc); 96 97 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 98 99 return crypto_shash_export(desc, out); 100 } 101 102 static int hmac_import(struct shash_desc *pdesc, const void *in) 103 { 104 struct shash_desc *desc = shash_desc_ctx(pdesc); 105 struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm); 106 107 desc->tfm = ctx->hash; 108 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 109 110 return crypto_shash_import(desc, in); 111 } 112 113 static int hmac_init(struct shash_desc *pdesc) 114 { 115 return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm)); 116 } 117 118 static int hmac_update(struct shash_desc *pdesc, 119 const u8 *data, unsigned int nbytes) 120 { 121 struct shash_desc *desc = shash_desc_ctx(pdesc); 122 123 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 124 125 return crypto_shash_update(desc, data, nbytes); 126 } 127 128 static int hmac_final(struct shash_desc *pdesc, u8 *out) 129 { 130 struct crypto_shash *parent = pdesc->tfm; 131 int ds = crypto_shash_digestsize(parent); 132 int ss = crypto_shash_statesize(parent); 133 char *opad = crypto_shash_ctx_aligned(parent) + ss; 134 struct shash_desc *desc = shash_desc_ctx(pdesc); 135 136 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 137 138 return crypto_shash_final(desc, out) ?: 139 crypto_shash_import(desc, opad) ?: 140 crypto_shash_finup(desc, out, ds, out); 141 } 142 143 static int hmac_finup(struct shash_desc *pdesc, const u8 *data, 144 unsigned int nbytes, u8 *out) 145 { 146 147 struct crypto_shash *parent = pdesc->tfm; 148 int ds = crypto_shash_digestsize(parent); 149 int ss = crypto_shash_statesize(parent); 150 char *opad = crypto_shash_ctx_aligned(parent) + ss; 151 struct shash_desc *desc = shash_desc_ctx(pdesc); 152 153 desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 154 155 return crypto_shash_finup(desc, data, nbytes, out) ?: 156 crypto_shash_import(desc, opad) ?: 157 crypto_shash_finup(desc, out, ds, out); 158 } 159 160 static int hmac_init_tfm(struct crypto_tfm *tfm) 161 { 162 struct crypto_shash *parent = __crypto_shash_cast(tfm); 163 struct crypto_shash *hash; 164 struct crypto_instance *inst = (void *)tfm->__crt_alg; 165 struct crypto_shash_spawn *spawn = crypto_instance_ctx(inst); 166 struct hmac_ctx *ctx = hmac_ctx(parent); 167 168 hash = crypto_spawn_shash(spawn); 169 if (IS_ERR(hash)) 170 return PTR_ERR(hash); 171 172 parent->descsize = sizeof(struct shash_desc) + 173 crypto_shash_descsize(hash); 174 175 ctx->hash = hash; 176 return 0; 177 } 178 179 static void hmac_exit_tfm(struct crypto_tfm *tfm) 180 { 181 struct hmac_ctx *ctx = hmac_ctx(__crypto_shash_cast(tfm)); 182 crypto_free_shash(ctx->hash); 183 } 184 185 static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb) 186 { 187 struct shash_instance *inst; 188 struct crypto_alg *alg; 189 struct shash_alg *salg; 190 int err; 191 int ds; 192 int ss; 193 194 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH); 195 if (err) 196 return err; 197 198 salg = shash_attr_alg(tb[1], 0, 0); 199 if (IS_ERR(salg)) 200 return PTR_ERR(salg); 201 202 err = -EINVAL; 203 ds = salg->digestsize; 204 ss = salg->statesize; 205 alg = &salg->base; 206 if (ds > alg->cra_blocksize || 207 ss < alg->cra_blocksize) 208 goto out_put_alg; 209 210 inst = shash_alloc_instance("hmac", alg); 211 err = PTR_ERR(inst); 212 if (IS_ERR(inst)) 213 goto out_put_alg; 214 215 err = crypto_init_shash_spawn(shash_instance_ctx(inst), salg, 216 shash_crypto_instance(inst)); 217 if (err) 218 goto out_free_inst; 219 220 inst->alg.base.cra_priority = alg->cra_priority; 221 inst->alg.base.cra_blocksize = alg->cra_blocksize; 222 inst->alg.base.cra_alignmask = alg->cra_alignmask; 223 224 ss = ALIGN(ss, alg->cra_alignmask + 1); 225 inst->alg.digestsize = ds; 226 inst->alg.statesize = ss; 227 228 inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) + 229 ALIGN(ss * 2, crypto_tfm_ctx_alignment()); 230 231 inst->alg.base.cra_init = hmac_init_tfm; 232 inst->alg.base.cra_exit = hmac_exit_tfm; 233 234 inst->alg.init = hmac_init; 235 inst->alg.update = hmac_update; 236 inst->alg.final = hmac_final; 237 inst->alg.finup = hmac_finup; 238 inst->alg.export = hmac_export; 239 inst->alg.import = hmac_import; 240 inst->alg.setkey = hmac_setkey; 241 242 err = shash_register_instance(tmpl, inst); 243 if (err) { 244 out_free_inst: 245 shash_free_instance(shash_crypto_instance(inst)); 246 } 247 248 out_put_alg: 249 crypto_mod_put(alg); 250 return err; 251 } 252 253 static struct crypto_template hmac_tmpl = { 254 .name = "hmac", 255 .create = hmac_create, 256 .free = shash_free_instance, 257 .module = THIS_MODULE, 258 }; 259 260 static int __init hmac_module_init(void) 261 { 262 return crypto_register_template(&hmac_tmpl); 263 } 264 265 static void __exit hmac_module_exit(void) 266 { 267 crypto_unregister_template(&hmac_tmpl); 268 } 269 270 module_init(hmac_module_init); 271 module_exit(hmac_module_exit); 272 273 MODULE_LICENSE("GPL"); 274 MODULE_DESCRIPTION("HMAC hash algorithm"); 275