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 <linux/err.h> 21 #include <linux/init.h> 22 #include <linux/kernel.h> 23 #include <linux/module.h> 24 #include <linux/scatterlist.h> 25 #include <linux/slab.h> 26 #include <linux/string.h> 27 28 struct hmac_ctx { 29 struct crypto_hash *child; 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_hash *tfm) 38 { 39 return align_ptr(crypto_hash_ctx_aligned(tfm) + 40 crypto_hash_blocksize(tfm) * 2 + 41 crypto_hash_digestsize(tfm), sizeof(void *)); 42 } 43 44 static int hmac_setkey(struct crypto_hash *parent, 45 const u8 *inkey, unsigned int keylen) 46 { 47 int bs = crypto_hash_blocksize(parent); 48 int ds = crypto_hash_digestsize(parent); 49 char *ipad = crypto_hash_ctx_aligned(parent); 50 char *opad = ipad + bs; 51 char *digest = opad + bs; 52 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *)); 53 struct crypto_hash *tfm = ctx->child; 54 unsigned int i; 55 56 if (keylen > bs) { 57 struct hash_desc desc; 58 struct scatterlist tmp; 59 int err; 60 61 desc.tfm = tfm; 62 desc.flags = crypto_hash_get_flags(parent); 63 desc.flags &= CRYPTO_TFM_REQ_MAY_SLEEP; 64 sg_init_one(&tmp, inkey, keylen); 65 66 err = crypto_hash_digest(&desc, &tmp, keylen, digest); 67 if (err) 68 return err; 69 70 inkey = digest; 71 keylen = ds; 72 } 73 74 memcpy(ipad, inkey, keylen); 75 memset(ipad + keylen, 0, bs - keylen); 76 memcpy(opad, ipad, bs); 77 78 for (i = 0; i < bs; i++) { 79 ipad[i] ^= 0x36; 80 opad[i] ^= 0x5c; 81 } 82 83 return 0; 84 } 85 86 static int hmac_init(struct hash_desc *pdesc) 87 { 88 struct crypto_hash *parent = pdesc->tfm; 89 int bs = crypto_hash_blocksize(parent); 90 int ds = crypto_hash_digestsize(parent); 91 char *ipad = crypto_hash_ctx_aligned(parent); 92 struct hmac_ctx *ctx = align_ptr(ipad + bs * 2 + ds, sizeof(void *)); 93 struct hash_desc desc; 94 struct scatterlist tmp; 95 int err; 96 97 desc.tfm = ctx->child; 98 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 99 sg_init_one(&tmp, ipad, bs); 100 101 err = crypto_hash_init(&desc); 102 if (unlikely(err)) 103 return err; 104 105 return crypto_hash_update(&desc, &tmp, bs); 106 } 107 108 static int hmac_update(struct hash_desc *pdesc, 109 struct scatterlist *sg, unsigned int nbytes) 110 { 111 struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm); 112 struct hash_desc desc; 113 114 desc.tfm = ctx->child; 115 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 116 117 return crypto_hash_update(&desc, sg, nbytes); 118 } 119 120 static int hmac_final(struct hash_desc *pdesc, u8 *out) 121 { 122 struct crypto_hash *parent = pdesc->tfm; 123 int bs = crypto_hash_blocksize(parent); 124 int ds = crypto_hash_digestsize(parent); 125 char *opad = crypto_hash_ctx_aligned(parent) + bs; 126 char *digest = opad + bs; 127 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *)); 128 struct hash_desc desc; 129 struct scatterlist tmp; 130 int err; 131 132 desc.tfm = ctx->child; 133 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 134 sg_init_one(&tmp, opad, bs + ds); 135 136 err = crypto_hash_final(&desc, digest); 137 if (unlikely(err)) 138 return err; 139 140 return crypto_hash_digest(&desc, &tmp, bs + ds, out); 141 } 142 143 static int hmac_digest(struct hash_desc *pdesc, struct scatterlist *sg, 144 unsigned int nbytes, u8 *out) 145 { 146 struct crypto_hash *parent = pdesc->tfm; 147 int bs = crypto_hash_blocksize(parent); 148 int ds = crypto_hash_digestsize(parent); 149 char *ipad = crypto_hash_ctx_aligned(parent); 150 char *opad = ipad + bs; 151 char *digest = opad + bs; 152 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *)); 153 struct hash_desc desc; 154 struct scatterlist sg1[2]; 155 struct scatterlist sg2[1]; 156 int err; 157 158 desc.tfm = ctx->child; 159 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 160 161 sg_init_table(sg1, 2); 162 sg_set_buf(sg1, ipad, bs); 163 sg_set_page(&sg1[1], (void *) sg, 0, 0); 164 165 sg_init_table(sg2, 1); 166 sg_set_buf(sg2, opad, bs + ds); 167 168 err = crypto_hash_digest(&desc, sg1, nbytes + bs, digest); 169 if (unlikely(err)) 170 return err; 171 172 return crypto_hash_digest(&desc, sg2, bs + ds, out); 173 } 174 175 static int hmac_init_tfm(struct crypto_tfm *tfm) 176 { 177 struct crypto_hash *hash; 178 struct crypto_instance *inst = (void *)tfm->__crt_alg; 179 struct crypto_spawn *spawn = crypto_instance_ctx(inst); 180 struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm)); 181 182 hash = crypto_spawn_hash(spawn); 183 if (IS_ERR(hash)) 184 return PTR_ERR(hash); 185 186 ctx->child = hash; 187 return 0; 188 } 189 190 static void hmac_exit_tfm(struct crypto_tfm *tfm) 191 { 192 struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm)); 193 crypto_free_hash(ctx->child); 194 } 195 196 static void hmac_free(struct crypto_instance *inst) 197 { 198 crypto_drop_spawn(crypto_instance_ctx(inst)); 199 kfree(inst); 200 } 201 202 static struct crypto_instance *hmac_alloc(struct rtattr **tb) 203 { 204 struct crypto_instance *inst; 205 struct crypto_alg *alg; 206 int err; 207 208 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_HASH); 209 if (err) 210 return ERR_PTR(err); 211 212 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_HASH, 213 CRYPTO_ALG_TYPE_HASH_MASK); 214 if (IS_ERR(alg)) 215 return ERR_PTR(PTR_ERR(alg)); 216 217 inst = crypto_alloc_instance("hmac", alg); 218 if (IS_ERR(inst)) 219 goto out_put_alg; 220 221 inst->alg.cra_flags = CRYPTO_ALG_TYPE_HASH; 222 inst->alg.cra_priority = alg->cra_priority; 223 inst->alg.cra_blocksize = alg->cra_blocksize; 224 inst->alg.cra_alignmask = alg->cra_alignmask; 225 inst->alg.cra_type = &crypto_hash_type; 226 227 inst->alg.cra_hash.digestsize = 228 (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) == 229 CRYPTO_ALG_TYPE_HASH ? alg->cra_hash.digestsize : 230 alg->cra_digest.dia_digestsize; 231 232 inst->alg.cra_ctxsize = sizeof(struct hmac_ctx) + 233 ALIGN(inst->alg.cra_blocksize * 2 + 234 inst->alg.cra_hash.digestsize, 235 sizeof(void *)); 236 237 inst->alg.cra_init = hmac_init_tfm; 238 inst->alg.cra_exit = hmac_exit_tfm; 239 240 inst->alg.cra_hash.init = hmac_init; 241 inst->alg.cra_hash.update = hmac_update; 242 inst->alg.cra_hash.final = hmac_final; 243 inst->alg.cra_hash.digest = hmac_digest; 244 inst->alg.cra_hash.setkey = hmac_setkey; 245 246 out_put_alg: 247 crypto_mod_put(alg); 248 return inst; 249 } 250 251 static struct crypto_template hmac_tmpl = { 252 .name = "hmac", 253 .alloc = hmac_alloc, 254 .free = hmac_free, 255 .module = THIS_MODULE, 256 }; 257 258 static int __init hmac_module_init(void) 259 { 260 return crypto_register_template(&hmac_tmpl); 261 } 262 263 static void __exit hmac_module_exit(void) 264 { 265 crypto_unregister_template(&hmac_tmpl); 266 } 267 268 module_init(hmac_module_init); 269 module_exit(hmac_module_exit); 270 271 MODULE_LICENSE("GPL"); 272 MODULE_DESCRIPTION("HMAC hash algorithm"); 273