| 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 | 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 | |
| 92 | static 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 | |
| 101 | static 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 | |
| 112 | static int hmac_init(struct shash_desc *pdesc) |
| 113 | { |
| 114 | return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm)); |
| 115 | } |
| 116 | |
| 117 | static 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 | |
| 127 | static 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 | |
| 142 | static 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 | |
| 159 | static 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 | |
| 178 | static 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 | |
| 184 | static 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) { |
| 243 | out_free_inst: |
| 244 | shash_free_instance(shash_crypto_instance(inst)); |
| 245 | } |
| 246 | |
| 247 | out_put_alg: |
| 248 | crypto_mod_put(alg); |
| 249 | return err; |
| 250 | } |
| 251 | |
| 252 | static struct crypto_template hmac_tmpl = { |
| 253 | .name = "hmac", |
| 254 | .create = hmac_create, |
| 255 | .free = shash_free_instance, |
| 256 | .module = THIS_MODULE, |
| 257 | }; |
| 258 | |
| 259 | static int __init hmac_module_init(void) |
| 260 | { |
| 261 | return crypto_register_template(&hmac_tmpl); |
| 262 | } |
| 263 | |
| 264 | static void __exit hmac_module_exit(void) |
| 265 | { |
| 266 | crypto_unregister_template(&hmac_tmpl); |
| 267 | } |
| 268 | |
| 269 | module_init(hmac_module_init); |
| 270 | module_exit(hmac_module_exit); |
| 271 | |
| 272 | MODULE_LICENSE("GPL"); |
| 273 | MODULE_DESCRIPTION("HMAC hash algorithm"); |