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/algapi.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_hash *child; 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_hash *tfm) 39 { 40 return align_ptr(crypto_hash_ctx_aligned(tfm) + 41 crypto_hash_blocksize(tfm) * 2 + 42 crypto_hash_digestsize(tfm), sizeof(void *)); 43 } 44 45 static int hmac_setkey(struct crypto_hash *parent, 46 const u8 *inkey, unsigned int keylen) 47 { 48 int bs = crypto_hash_blocksize(parent); 49 int ds = crypto_hash_digestsize(parent); 50 char *ipad = crypto_hash_ctx_aligned(parent); 51 char *opad = ipad + bs; 52 char *digest = opad + bs; 53 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *)); 54 struct crypto_hash *tfm = ctx->child; 55 unsigned int i; 56 57 if (keylen > bs) { 58 struct hash_desc desc; 59 struct scatterlist tmp; 60 int err; 61 62 desc.tfm = tfm; 63 desc.flags = crypto_hash_get_flags(parent); 64 desc.flags &= CRYPTO_TFM_REQ_MAY_SLEEP; 65 sg_init_one(&tmp, inkey, keylen); 66 67 err = crypto_hash_digest(&desc, &tmp, keylen, digest); 68 if (err) 69 return err; 70 71 inkey = digest; 72 keylen = ds; 73 } 74 75 memcpy(ipad, inkey, keylen); 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 0; 85 } 86 87 static int hmac_init(struct hash_desc *pdesc) 88 { 89 struct crypto_hash *parent = pdesc->tfm; 90 int bs = crypto_hash_blocksize(parent); 91 int ds = crypto_hash_digestsize(parent); 92 char *ipad = crypto_hash_ctx_aligned(parent); 93 struct hmac_ctx *ctx = align_ptr(ipad + bs * 2 + ds, sizeof(void *)); 94 struct hash_desc desc; 95 struct scatterlist tmp; 96 int err; 97 98 desc.tfm = ctx->child; 99 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 100 sg_init_one(&tmp, ipad, bs); 101 102 err = crypto_hash_init(&desc); 103 if (unlikely(err)) 104 return err; 105 106 return crypto_hash_update(&desc, &tmp, bs); 107 } 108 109 static int hmac_update(struct hash_desc *pdesc, 110 struct scatterlist *sg, unsigned int nbytes) 111 { 112 struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm); 113 struct hash_desc desc; 114 115 desc.tfm = ctx->child; 116 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 117 118 return crypto_hash_update(&desc, sg, nbytes); 119 } 120 121 static int hmac_final(struct hash_desc *pdesc, u8 *out) 122 { 123 struct crypto_hash *parent = pdesc->tfm; 124 int bs = crypto_hash_blocksize(parent); 125 int ds = crypto_hash_digestsize(parent); 126 char *opad = crypto_hash_ctx_aligned(parent) + bs; 127 char *digest = opad + bs; 128 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *)); 129 struct hash_desc desc; 130 struct scatterlist tmp; 131 int err; 132 133 desc.tfm = ctx->child; 134 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 135 sg_init_one(&tmp, opad, bs + ds); 136 137 err = crypto_hash_final(&desc, digest); 138 if (unlikely(err)) 139 return err; 140 141 return crypto_hash_digest(&desc, &tmp, bs + ds, out); 142 } 143 144 static int hmac_digest(struct hash_desc *pdesc, struct scatterlist *sg, 145 unsigned int nbytes, u8 *out) 146 { 147 struct crypto_hash *parent = pdesc->tfm; 148 int bs = crypto_hash_blocksize(parent); 149 int ds = crypto_hash_digestsize(parent); 150 char *ipad = crypto_hash_ctx_aligned(parent); 151 char *opad = ipad + bs; 152 char *digest = opad + bs; 153 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *)); 154 struct hash_desc desc; 155 struct scatterlist sg1[2]; 156 struct scatterlist sg2[1]; 157 int err; 158 159 desc.tfm = ctx->child; 160 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 161 162 sg_init_table(sg1, 2); 163 sg_set_buf(sg1, ipad, bs); 164 scatterwalk_sg_chain(sg1, 2, sg); 165 166 sg_init_table(sg2, 1); 167 sg_set_buf(sg2, opad, bs + ds); 168 169 err = crypto_hash_digest(&desc, sg1, nbytes + bs, digest); 170 if (unlikely(err)) 171 return err; 172 173 return crypto_hash_digest(&desc, sg2, bs + ds, out); 174 } 175 176 static int hmac_init_tfm(struct crypto_tfm *tfm) 177 { 178 struct crypto_hash *hash; 179 struct crypto_instance *inst = (void *)tfm->__crt_alg; 180 struct crypto_spawn *spawn = crypto_instance_ctx(inst); 181 struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm)); 182 183 hash = crypto_spawn_hash(spawn); 184 if (IS_ERR(hash)) 185 return PTR_ERR(hash); 186 187 ctx->child = hash; 188 return 0; 189 } 190 191 static void hmac_exit_tfm(struct crypto_tfm *tfm) 192 { 193 struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm)); 194 crypto_free_hash(ctx->child); 195 } 196 197 static void hmac_free(struct crypto_instance *inst) 198 { 199 crypto_drop_spawn(crypto_instance_ctx(inst)); 200 kfree(inst); 201 } 202 203 static struct crypto_instance *hmac_alloc(struct rtattr **tb) 204 { 205 struct crypto_instance *inst; 206 struct crypto_alg *alg; 207 int err; 208 209 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_HASH); 210 if (err) 211 return ERR_PTR(err); 212 213 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_HASH, 214 CRYPTO_ALG_TYPE_HASH_MASK); 215 if (IS_ERR(alg)) 216 return ERR_CAST(alg); 217 218 inst = crypto_alloc_instance("hmac", alg); 219 if (IS_ERR(inst)) 220 goto out_put_alg; 221 222 inst->alg.cra_flags = CRYPTO_ALG_TYPE_HASH; 223 inst->alg.cra_priority = alg->cra_priority; 224 inst->alg.cra_blocksize = alg->cra_blocksize; 225 inst->alg.cra_alignmask = alg->cra_alignmask; 226 inst->alg.cra_type = &crypto_hash_type; 227 228 inst->alg.cra_hash.digestsize = 229 (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) == 230 CRYPTO_ALG_TYPE_HASH ? alg->cra_hash.digestsize : 231 alg->cra_digest.dia_digestsize; 232 233 inst->alg.cra_ctxsize = sizeof(struct hmac_ctx) + 234 ALIGN(inst->alg.cra_blocksize * 2 + 235 inst->alg.cra_hash.digestsize, 236 sizeof(void *)); 237 238 inst->alg.cra_init = hmac_init_tfm; 239 inst->alg.cra_exit = hmac_exit_tfm; 240 241 inst->alg.cra_hash.init = hmac_init; 242 inst->alg.cra_hash.update = hmac_update; 243 inst->alg.cra_hash.final = hmac_final; 244 inst->alg.cra_hash.digest = hmac_digest; 245 inst->alg.cra_hash.setkey = hmac_setkey; 246 247 out_put_alg: 248 crypto_mod_put(alg); 249 return inst; 250 } 251 252 static struct crypto_template hmac_tmpl = { 253 .name = "hmac", 254 .alloc = hmac_alloc, 255 .free = hmac_free, 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"); 274