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 96 desc.tfm = ctx->child; 97 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 98 sg_set_buf(&tmp, ipad, bs); 99 100 return unlikely(crypto_hash_init(&desc)) ?: 101 crypto_hash_update(&desc, &tmp, 1); 102 } 103 104 static int hmac_update(struct hash_desc *pdesc, 105 struct scatterlist *sg, unsigned int nbytes) 106 { 107 struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm); 108 struct hash_desc desc; 109 110 desc.tfm = ctx->child; 111 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 112 113 return crypto_hash_update(&desc, sg, nbytes); 114 } 115 116 static int hmac_final(struct hash_desc *pdesc, u8 *out) 117 { 118 struct crypto_hash *parent = pdesc->tfm; 119 int bs = crypto_hash_blocksize(parent); 120 int ds = crypto_hash_digestsize(parent); 121 char *opad = crypto_hash_ctx_aligned(parent) + bs; 122 char *digest = opad + bs; 123 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *)); 124 struct hash_desc desc; 125 struct scatterlist tmp; 126 127 desc.tfm = ctx->child; 128 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 129 sg_set_buf(&tmp, opad, bs + ds); 130 131 return unlikely(crypto_hash_final(&desc, digest)) ?: 132 crypto_hash_digest(&desc, &tmp, bs + ds, out); 133 } 134 135 static int hmac_digest(struct hash_desc *pdesc, struct scatterlist *sg, 136 unsigned int nbytes, u8 *out) 137 { 138 struct crypto_hash *parent = pdesc->tfm; 139 int bs = crypto_hash_blocksize(parent); 140 int ds = crypto_hash_digestsize(parent); 141 char *ipad = crypto_hash_ctx_aligned(parent); 142 char *opad = ipad + bs; 143 char *digest = opad + bs; 144 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *)); 145 struct hash_desc desc; 146 struct scatterlist sg1[2]; 147 struct scatterlist sg2[1]; 148 149 desc.tfm = ctx->child; 150 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; 151 152 sg_set_buf(sg1, ipad, bs); 153 sg1[1].page = (void *)sg; 154 sg1[1].length = 0; 155 sg_set_buf(sg2, opad, bs + ds); 156 157 return unlikely(crypto_hash_digest(&desc, sg1, nbytes + bs, digest)) ?: 158 crypto_hash_digest(&desc, sg2, bs + ds, out); 159 } 160 161 static int hmac_init_tfm(struct crypto_tfm *tfm) 162 { 163 struct crypto_instance *inst = (void *)tfm->__crt_alg; 164 struct crypto_spawn *spawn = crypto_instance_ctx(inst); 165 struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm)); 166 167 tfm = crypto_spawn_tfm(spawn); 168 if (IS_ERR(tfm)) 169 return PTR_ERR(tfm); 170 171 ctx->child = crypto_hash_cast(tfm); 172 return 0; 173 } 174 175 static void hmac_exit_tfm(struct crypto_tfm *tfm) 176 { 177 struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm)); 178 crypto_free_hash(ctx->child); 179 } 180 181 static void hmac_free(struct crypto_instance *inst) 182 { 183 crypto_drop_spawn(crypto_instance_ctx(inst)); 184 kfree(inst); 185 } 186 187 static struct crypto_instance *hmac_alloc(void *param, unsigned int len) 188 { 189 struct crypto_instance *inst; 190 struct crypto_alg *alg; 191 192 alg = crypto_get_attr_alg(param, len, CRYPTO_ALG_TYPE_HASH, 193 CRYPTO_ALG_TYPE_HASH_MASK | CRYPTO_ALG_ASYNC); 194 if (IS_ERR(alg)) 195 return ERR_PTR(PTR_ERR(alg)); 196 197 inst = crypto_alloc_instance("hmac", alg); 198 if (IS_ERR(inst)) 199 goto out_put_alg; 200 201 inst->alg.cra_flags = CRYPTO_ALG_TYPE_HASH; 202 inst->alg.cra_priority = alg->cra_priority; 203 inst->alg.cra_blocksize = alg->cra_blocksize; 204 inst->alg.cra_alignmask = alg->cra_alignmask; 205 inst->alg.cra_type = &crypto_hash_type; 206 207 inst->alg.cra_hash.digestsize = 208 (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) == 209 CRYPTO_ALG_TYPE_HASH ? alg->cra_hash.digestsize : 210 alg->cra_digest.dia_digestsize; 211 212 inst->alg.cra_ctxsize = sizeof(struct hmac_ctx) + 213 ALIGN(inst->alg.cra_blocksize * 2 + 214 inst->alg.cra_hash.digestsize, 215 sizeof(void *)); 216 217 inst->alg.cra_init = hmac_init_tfm; 218 inst->alg.cra_exit = hmac_exit_tfm; 219 220 inst->alg.cra_hash.init = hmac_init; 221 inst->alg.cra_hash.update = hmac_update; 222 inst->alg.cra_hash.final = hmac_final; 223 inst->alg.cra_hash.digest = hmac_digest; 224 inst->alg.cra_hash.setkey = hmac_setkey; 225 226 out_put_alg: 227 crypto_mod_put(alg); 228 return inst; 229 } 230 231 static struct crypto_template hmac_tmpl = { 232 .name = "hmac", 233 .alloc = hmac_alloc, 234 .free = hmac_free, 235 .module = THIS_MODULE, 236 }; 237 238 static int __init hmac_module_init(void) 239 { 240 return crypto_register_template(&hmac_tmpl); 241 } 242 243 static void __exit hmac_module_exit(void) 244 { 245 crypto_unregister_template(&hmac_tmpl); 246 } 247 248 module_init(hmac_module_init); 249 module_exit(hmac_module_exit); 250 251 MODULE_LICENSE("GPL"); 252 MODULE_DESCRIPTION("HMAC hash algorithm"); 253