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_set_buf(&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_set_buf(&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_set_buf(&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_set_buf(sg1, ipad, bs); 162 sg1[1].page = (void *)sg; 163 sg1[1].length = 0; 164 sg_set_buf(sg2, opad, bs + ds); 165 166 err = crypto_hash_digest(&desc, sg1, nbytes + bs, digest); 167 if (unlikely(err)) 168 return err; 169 170 return crypto_hash_digest(&desc, sg2, bs + ds, out); 171 } 172 173 static int hmac_init_tfm(struct crypto_tfm *tfm) 174 { 175 struct crypto_hash *hash; 176 struct crypto_instance *inst = (void *)tfm->__crt_alg; 177 struct crypto_spawn *spawn = crypto_instance_ctx(inst); 178 struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm)); 179 180 hash = crypto_spawn_hash(spawn); 181 if (IS_ERR(hash)) 182 return PTR_ERR(hash); 183 184 ctx->child = hash; 185 return 0; 186 } 187 188 static void hmac_exit_tfm(struct crypto_tfm *tfm) 189 { 190 struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm)); 191 crypto_free_hash(ctx->child); 192 } 193 194 static void hmac_free(struct crypto_instance *inst) 195 { 196 crypto_drop_spawn(crypto_instance_ctx(inst)); 197 kfree(inst); 198 } 199 200 static struct crypto_instance *hmac_alloc(void *param, unsigned int len) 201 { 202 struct crypto_instance *inst; 203 struct crypto_alg *alg; 204 205 alg = crypto_get_attr_alg(param, len, CRYPTO_ALG_TYPE_HASH, 206 CRYPTO_ALG_TYPE_HASH_MASK | CRYPTO_ALG_ASYNC); 207 if (IS_ERR(alg)) 208 return ERR_PTR(PTR_ERR(alg)); 209 210 inst = crypto_alloc_instance("hmac", alg); 211 if (IS_ERR(inst)) 212 goto out_put_alg; 213 214 inst->alg.cra_flags = CRYPTO_ALG_TYPE_HASH; 215 inst->alg.cra_priority = alg->cra_priority; 216 inst->alg.cra_blocksize = alg->cra_blocksize; 217 inst->alg.cra_alignmask = alg->cra_alignmask; 218 inst->alg.cra_type = &crypto_hash_type; 219 220 inst->alg.cra_hash.digestsize = 221 (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) == 222 CRYPTO_ALG_TYPE_HASH ? alg->cra_hash.digestsize : 223 alg->cra_digest.dia_digestsize; 224 225 inst->alg.cra_ctxsize = sizeof(struct hmac_ctx) + 226 ALIGN(inst->alg.cra_blocksize * 2 + 227 inst->alg.cra_hash.digestsize, 228 sizeof(void *)); 229 230 inst->alg.cra_init = hmac_init_tfm; 231 inst->alg.cra_exit = hmac_exit_tfm; 232 233 inst->alg.cra_hash.init = hmac_init; 234 inst->alg.cra_hash.update = hmac_update; 235 inst->alg.cra_hash.final = hmac_final; 236 inst->alg.cra_hash.digest = hmac_digest; 237 inst->alg.cra_hash.setkey = hmac_setkey; 238 239 out_put_alg: 240 crypto_mod_put(alg); 241 return inst; 242 } 243 244 static struct crypto_template hmac_tmpl = { 245 .name = "hmac", 246 .alloc = hmac_alloc, 247 .free = hmac_free, 248 .module = THIS_MODULE, 249 }; 250 251 static int __init hmac_module_init(void) 252 { 253 return crypto_register_template(&hmac_tmpl); 254 } 255 256 static void __exit hmac_module_exit(void) 257 { 258 crypto_unregister_template(&hmac_tmpl); 259 } 260 261 module_init(hmac_module_init); 262 module_exit(hmac_module_exit); 263 264 MODULE_LICENSE("GPL"); 265 MODULE_DESCRIPTION("HMAC hash algorithm"); 266