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/fips.h> 19 #include <linux/init.h> 20 #include <linux/kernel.h> 21 #include <linux/module.h> 22 #include <linux/scatterlist.h> 23 #include <linux/string.h> 24 25 struct hmac_ctx { 26 struct crypto_shash *hash; 27 }; 28 29 static inline void *align_ptr(void *p, unsigned int align) 30 { 31 return (void *)ALIGN((unsigned long)p, align); 32 } 33 34 static inline struct hmac_ctx *hmac_ctx(struct crypto_shash *tfm) 35 { 36 return align_ptr(crypto_shash_ctx_aligned(tfm) + 37 crypto_shash_statesize(tfm) * 2, 38 crypto_tfm_ctx_alignment()); 39 } 40 41 static int hmac_setkey(struct crypto_shash *parent, 42 const u8 *inkey, unsigned int keylen) 43 { 44 int bs = crypto_shash_blocksize(parent); 45 int ds = crypto_shash_digestsize(parent); 46 int ss = crypto_shash_statesize(parent); 47 char *ipad = crypto_shash_ctx_aligned(parent); 48 char *opad = ipad + ss; 49 struct hmac_ctx *ctx = align_ptr(opad + ss, 50 crypto_tfm_ctx_alignment()); 51 struct crypto_shash *hash = ctx->hash; 52 SHASH_DESC_ON_STACK(shash, hash); 53 unsigned int i; 54 55 if (fips_enabled && (keylen < 112 / 8)) 56 return -EINVAL; 57 58 shash->tfm = hash; 59 60 if (keylen > bs) { 61 int err; 62 63 err = crypto_shash_digest(shash, inkey, keylen, ipad); 64 if (err) 65 return err; 66 67 keylen = ds; 68 } else 69 memcpy(ipad, inkey, keylen); 70 71 memset(ipad + keylen, 0, bs - keylen); 72 memcpy(opad, ipad, bs); 73 74 for (i = 0; i < bs; i++) { 75 ipad[i] ^= HMAC_IPAD_VALUE; 76 opad[i] ^= HMAC_OPAD_VALUE; 77 } 78 79 return crypto_shash_init(shash) ?: 80 crypto_shash_update(shash, ipad, bs) ?: 81 crypto_shash_export(shash, ipad) ?: 82 crypto_shash_init(shash) ?: 83 crypto_shash_update(shash, opad, bs) ?: 84 crypto_shash_export(shash, opad); 85 } 86 87 static int hmac_export(struct shash_desc *pdesc, void *out) 88 { 89 struct shash_desc *desc = shash_desc_ctx(pdesc); 90 91 return crypto_shash_export(desc, out); 92 } 93 94 static int hmac_import(struct shash_desc *pdesc, const void *in) 95 { 96 struct shash_desc *desc = shash_desc_ctx(pdesc); 97 struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm); 98 99 desc->tfm = ctx->hash; 100 101 return crypto_shash_import(desc, in); 102 } 103 104 static int hmac_init(struct shash_desc *pdesc) 105 { 106 return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm)); 107 } 108 109 static int hmac_update(struct shash_desc *pdesc, 110 const u8 *data, unsigned int nbytes) 111 { 112 struct shash_desc *desc = shash_desc_ctx(pdesc); 113 114 return crypto_shash_update(desc, data, nbytes); 115 } 116 117 static int hmac_final(struct shash_desc *pdesc, u8 *out) 118 { 119 struct crypto_shash *parent = pdesc->tfm; 120 int ds = crypto_shash_digestsize(parent); 121 int ss = crypto_shash_statesize(parent); 122 char *opad = crypto_shash_ctx_aligned(parent) + ss; 123 struct shash_desc *desc = shash_desc_ctx(pdesc); 124 125 return crypto_shash_final(desc, out) ?: 126 crypto_shash_import(desc, opad) ?: 127 crypto_shash_finup(desc, out, ds, out); 128 } 129 130 static int hmac_finup(struct shash_desc *pdesc, const u8 *data, 131 unsigned int nbytes, u8 *out) 132 { 133 134 struct crypto_shash *parent = pdesc->tfm; 135 int ds = crypto_shash_digestsize(parent); 136 int ss = crypto_shash_statesize(parent); 137 char *opad = crypto_shash_ctx_aligned(parent) + ss; 138 struct shash_desc *desc = shash_desc_ctx(pdesc); 139 140 return crypto_shash_finup(desc, data, nbytes, out) ?: 141 crypto_shash_import(desc, opad) ?: 142 crypto_shash_finup(desc, out, ds, out); 143 } 144 145 static int hmac_init_tfm(struct crypto_shash *parent) 146 { 147 struct crypto_shash *hash; 148 struct shash_instance *inst = shash_alg_instance(parent); 149 struct crypto_shash_spawn *spawn = shash_instance_ctx(inst); 150 struct hmac_ctx *ctx = hmac_ctx(parent); 151 152 hash = crypto_spawn_shash(spawn); 153 if (IS_ERR(hash)) 154 return PTR_ERR(hash); 155 156 parent->descsize = sizeof(struct shash_desc) + 157 crypto_shash_descsize(hash); 158 159 ctx->hash = hash; 160 return 0; 161 } 162 163 static int hmac_clone_tfm(struct crypto_shash *dst, struct crypto_shash *src) 164 { 165 struct hmac_ctx *sctx = hmac_ctx(src); 166 struct hmac_ctx *dctx = hmac_ctx(dst); 167 struct crypto_shash *hash; 168 169 hash = crypto_clone_shash(sctx->hash); 170 if (IS_ERR(hash)) 171 return PTR_ERR(hash); 172 173 dctx->hash = hash; 174 return 0; 175 } 176 177 static void hmac_exit_tfm(struct crypto_shash *parent) 178 { 179 struct hmac_ctx *ctx = hmac_ctx(parent); 180 crypto_free_shash(ctx->hash); 181 } 182 183 static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb) 184 { 185 struct shash_instance *inst; 186 struct crypto_shash_spawn *spawn; 187 struct crypto_alg *alg; 188 struct shash_alg *salg; 189 u32 mask; 190 int err; 191 int ds; 192 int ss; 193 194 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH, &mask); 195 if (err) 196 return err; 197 198 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL); 199 if (!inst) 200 return -ENOMEM; 201 spawn = shash_instance_ctx(inst); 202 203 err = crypto_grab_shash(spawn, shash_crypto_instance(inst), 204 crypto_attr_alg_name(tb[1]), 0, mask); 205 if (err) 206 goto err_free_inst; 207 salg = crypto_spawn_shash_alg(spawn); 208 alg = &salg->base; 209 210 /* The underlying hash algorithm must not require a key */ 211 err = -EINVAL; 212 if (crypto_shash_alg_needs_key(salg)) 213 goto err_free_inst; 214 215 ds = salg->digestsize; 216 ss = salg->statesize; 217 if (ds > alg->cra_blocksize || 218 ss < alg->cra_blocksize) 219 goto err_free_inst; 220 221 err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg); 222 if (err) 223 goto err_free_inst; 224 225 inst->alg.base.cra_priority = alg->cra_priority; 226 inst->alg.base.cra_blocksize = alg->cra_blocksize; 227 inst->alg.base.cra_alignmask = alg->cra_alignmask; 228 229 ss = ALIGN(ss, alg->cra_alignmask + 1); 230 inst->alg.digestsize = ds; 231 inst->alg.statesize = ss; 232 233 inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) + 234 ALIGN(ss * 2, crypto_tfm_ctx_alignment()); 235 236 inst->alg.init = hmac_init; 237 inst->alg.update = hmac_update; 238 inst->alg.final = hmac_final; 239 inst->alg.finup = hmac_finup; 240 inst->alg.export = hmac_export; 241 inst->alg.import = hmac_import; 242 inst->alg.setkey = hmac_setkey; 243 inst->alg.init_tfm = hmac_init_tfm; 244 inst->alg.clone_tfm = hmac_clone_tfm; 245 inst->alg.exit_tfm = hmac_exit_tfm; 246 247 inst->free = shash_free_singlespawn_instance; 248 249 err = shash_register_instance(tmpl, inst); 250 if (err) { 251 err_free_inst: 252 shash_free_singlespawn_instance(inst); 253 } 254 return err; 255 } 256 257 static struct crypto_template hmac_tmpl = { 258 .name = "hmac", 259 .create = hmac_create, 260 .module = THIS_MODULE, 261 }; 262 263 static int __init hmac_module_init(void) 264 { 265 return crypto_register_template(&hmac_tmpl); 266 } 267 268 static void __exit hmac_module_exit(void) 269 { 270 crypto_unregister_template(&hmac_tmpl); 271 } 272 273 subsys_initcall(hmac_module_init); 274 module_exit(hmac_module_exit); 275 276 MODULE_LICENSE("GPL"); 277 MODULE_DESCRIPTION("HMAC hash algorithm"); 278 MODULE_ALIAS_CRYPTO("hmac"); 279