1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Cryptographic API. 4 * 5 * HMAC: Keyed-Hashing for Message Authentication (RFC2104). 6 * 7 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au> 8 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au> 9 * 10 * The HMAC implementation is derived from USAGI. 11 * Copyright (c) 2002 Kazunori Miyazawa <miyazawa@linux-ipv6.org> / USAGI 12 */ 13 14 #include <crypto/hmac.h> 15 #include <crypto/internal/hash.h> 16 #include <crypto/scatterwalk.h> 17 #include <linux/err.h> 18 #include <linux/init.h> 19 #include <linux/kernel.h> 20 #include <linux/module.h> 21 #include <linux/scatterlist.h> 22 #include <linux/string.h> 23 24 struct hmac_ctx { 25 struct crypto_shash *hash; 26 }; 27 28 static inline void *align_ptr(void *p, unsigned int align) 29 { 30 return (void *)ALIGN((unsigned long)p, align); 31 } 32 33 static inline struct hmac_ctx *hmac_ctx(struct crypto_shash *tfm) 34 { 35 return align_ptr(crypto_shash_ctx_aligned(tfm) + 36 crypto_shash_statesize(tfm) * 2, 37 crypto_tfm_ctx_alignment()); 38 } 39 40 static int hmac_setkey(struct crypto_shash *parent, 41 const u8 *inkey, unsigned int keylen) 42 { 43 int bs = crypto_shash_blocksize(parent); 44 int ds = crypto_shash_digestsize(parent); 45 int ss = crypto_shash_statesize(parent); 46 char *ipad = crypto_shash_ctx_aligned(parent); 47 char *opad = ipad + ss; 48 struct hmac_ctx *ctx = align_ptr(opad + ss, 49 crypto_tfm_ctx_alignment()); 50 struct crypto_shash *hash = ctx->hash; 51 SHASH_DESC_ON_STACK(shash, hash); 52 unsigned int i; 53 54 shash->tfm = hash; 55 56 if (keylen > bs) { 57 int err; 58 59 err = crypto_shash_digest(shash, inkey, keylen, ipad); 60 if (err) 61 return err; 62 63 keylen = ds; 64 } else 65 memcpy(ipad, inkey, keylen); 66 67 memset(ipad + keylen, 0, bs - keylen); 68 memcpy(opad, ipad, bs); 69 70 for (i = 0; i < bs; i++) { 71 ipad[i] ^= HMAC_IPAD_VALUE; 72 opad[i] ^= HMAC_OPAD_VALUE; 73 } 74 75 return crypto_shash_init(shash) ?: 76 crypto_shash_update(shash, ipad, bs) ?: 77 crypto_shash_export(shash, ipad) ?: 78 crypto_shash_init(shash) ?: 79 crypto_shash_update(shash, opad, bs) ?: 80 crypto_shash_export(shash, opad); 81 } 82 83 static int hmac_export(struct shash_desc *pdesc, void *out) 84 { 85 struct shash_desc *desc = shash_desc_ctx(pdesc); 86 87 return crypto_shash_export(desc, out); 88 } 89 90 static int hmac_import(struct shash_desc *pdesc, const void *in) 91 { 92 struct shash_desc *desc = shash_desc_ctx(pdesc); 93 struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm); 94 95 desc->tfm = ctx->hash; 96 97 return crypto_shash_import(desc, in); 98 } 99 100 static int hmac_init(struct shash_desc *pdesc) 101 { 102 return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm)); 103 } 104 105 static int hmac_update(struct shash_desc *pdesc, 106 const u8 *data, unsigned int nbytes) 107 { 108 struct shash_desc *desc = shash_desc_ctx(pdesc); 109 110 return crypto_shash_update(desc, data, nbytes); 111 } 112 113 static int hmac_final(struct shash_desc *pdesc, u8 *out) 114 { 115 struct crypto_shash *parent = pdesc->tfm; 116 int ds = crypto_shash_digestsize(parent); 117 int ss = crypto_shash_statesize(parent); 118 char *opad = crypto_shash_ctx_aligned(parent) + ss; 119 struct shash_desc *desc = shash_desc_ctx(pdesc); 120 121 return crypto_shash_final(desc, out) ?: 122 crypto_shash_import(desc, opad) ?: 123 crypto_shash_finup(desc, out, ds, out); 124 } 125 126 static int hmac_finup(struct shash_desc *pdesc, const u8 *data, 127 unsigned int nbytes, u8 *out) 128 { 129 130 struct crypto_shash *parent = pdesc->tfm; 131 int ds = crypto_shash_digestsize(parent); 132 int ss = crypto_shash_statesize(parent); 133 char *opad = crypto_shash_ctx_aligned(parent) + ss; 134 struct shash_desc *desc = shash_desc_ctx(pdesc); 135 136 return crypto_shash_finup(desc, data, nbytes, out) ?: 137 crypto_shash_import(desc, opad) ?: 138 crypto_shash_finup(desc, out, ds, out); 139 } 140 141 static int hmac_init_tfm(struct crypto_shash *parent) 142 { 143 struct crypto_shash *hash; 144 struct shash_instance *inst = shash_alg_instance(parent); 145 struct crypto_shash_spawn *spawn = shash_instance_ctx(inst); 146 struct hmac_ctx *ctx = hmac_ctx(parent); 147 148 hash = crypto_spawn_shash(spawn); 149 if (IS_ERR(hash)) 150 return PTR_ERR(hash); 151 152 parent->descsize = sizeof(struct shash_desc) + 153 crypto_shash_descsize(hash); 154 155 ctx->hash = hash; 156 return 0; 157 } 158 159 static void hmac_exit_tfm(struct crypto_shash *parent) 160 { 161 struct hmac_ctx *ctx = hmac_ctx(parent); 162 crypto_free_shash(ctx->hash); 163 } 164 165 static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb) 166 { 167 struct shash_instance *inst; 168 struct crypto_shash_spawn *spawn; 169 struct crypto_alg *alg; 170 struct shash_alg *salg; 171 int err; 172 int ds; 173 int ss; 174 175 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH); 176 if (err) 177 return err; 178 179 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL); 180 if (!inst) 181 return -ENOMEM; 182 spawn = shash_instance_ctx(inst); 183 184 err = crypto_grab_shash(spawn, shash_crypto_instance(inst), 185 crypto_attr_alg_name(tb[1]), 0, 0); 186 if (err) 187 goto err_free_inst; 188 salg = crypto_spawn_shash_alg(spawn); 189 alg = &salg->base; 190 191 /* The underlying hash algorithm must not require a key */ 192 err = -EINVAL; 193 if (crypto_shash_alg_needs_key(salg)) 194 goto err_free_inst; 195 196 ds = salg->digestsize; 197 ss = salg->statesize; 198 if (ds > alg->cra_blocksize || 199 ss < alg->cra_blocksize) 200 goto err_free_inst; 201 202 err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg); 203 if (err) 204 goto err_free_inst; 205 206 inst->alg.base.cra_priority = alg->cra_priority; 207 inst->alg.base.cra_blocksize = alg->cra_blocksize; 208 inst->alg.base.cra_alignmask = alg->cra_alignmask; 209 210 ss = ALIGN(ss, alg->cra_alignmask + 1); 211 inst->alg.digestsize = ds; 212 inst->alg.statesize = ss; 213 214 inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) + 215 ALIGN(ss * 2, crypto_tfm_ctx_alignment()); 216 217 inst->alg.init = hmac_init; 218 inst->alg.update = hmac_update; 219 inst->alg.final = hmac_final; 220 inst->alg.finup = hmac_finup; 221 inst->alg.export = hmac_export; 222 inst->alg.import = hmac_import; 223 inst->alg.setkey = hmac_setkey; 224 inst->alg.init_tfm = hmac_init_tfm; 225 inst->alg.exit_tfm = hmac_exit_tfm; 226 227 inst->free = shash_free_singlespawn_instance; 228 229 err = shash_register_instance(tmpl, inst); 230 if (err) { 231 err_free_inst: 232 shash_free_singlespawn_instance(inst); 233 } 234 return err; 235 } 236 237 static struct crypto_template hmac_tmpl = { 238 .name = "hmac", 239 .create = hmac_create, 240 .module = THIS_MODULE, 241 }; 242 243 static int __init hmac_module_init(void) 244 { 245 return crypto_register_template(&hmac_tmpl); 246 } 247 248 static void __exit hmac_module_exit(void) 249 { 250 crypto_unregister_template(&hmac_tmpl); 251 } 252 253 subsys_initcall(hmac_module_init); 254 module_exit(hmac_module_exit); 255 256 MODULE_LICENSE("GPL"); 257 MODULE_DESCRIPTION("HMAC hash algorithm"); 258 MODULE_ALIAS_CRYPTO("hmac"); 259