crypto/skcipher.c

   1 /*
   2  * Symmetric key cipher operations.
   3  *
   4  * Generic encrypt/decrypt wrapper for ciphers, handles operations across
   5  * multiple page boundaries by using temporary blocks.  In user context,
   6  * the kernel is given a chance to schedule us once per page.
   7  *
   8  * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
   9  *
  10  * This program is free software; you can redistribute it and/or modify it
  11  * under the terms of the GNU General Public License as published by the Free
  12  * Software Foundation; either version 2 of the License, or (at your option)
  13  * any later version.
  14  *
  15  */
  16
  17 #include <crypto/internal/skcipher.h>
  18 #include <linux/bug.h>
  19 #include <linux/module.h>
  20
  21 #include "internal.h"
  22
  23 static unsigned int crypto_skcipher_extsize(struct crypto_alg *alg)
  24 {
  25         if (alg->cra_type == &crypto_blkcipher_type)
  26                 return sizeof(struct crypto_blkcipher *);
  27
  28         BUG_ON(alg->cra_type != &crypto_ablkcipher_type &&
  29                alg->cra_type != &crypto_givcipher_type);
  30
  31         return sizeof(struct crypto_ablkcipher *);
  32 }
  33
  34 static int skcipher_setkey_blkcipher(struct crypto_skcipher *tfm,
  35                                      const u8 *key, unsigned int keylen)
  36 {
  37         struct crypto_blkcipher **ctx = crypto_skcipher_ctx(tfm);
  38         struct crypto_blkcipher *blkcipher = *ctx;
  39         int err;
  40
  41         crypto_blkcipher_clear_flags(blkcipher, ~0);
  42         crypto_blkcipher_set_flags(blkcipher, crypto_skcipher_get_flags(tfm) &
  43                                               CRYPTO_TFM_REQ_MASK);
  44         err = crypto_blkcipher_setkey(blkcipher, key, keylen);
  45         crypto_skcipher_set_flags(tfm, crypto_blkcipher_get_flags(blkcipher) &
  46                                        CRYPTO_TFM_RES_MASK);
  47
  48         return err;
  49 }
  50
  51 static int skcipher_crypt_blkcipher(struct skcipher_request *req,
  52                                     int (*crypt)(struct blkcipher_desc *,
  53                                                  struct scatterlist *,
  54                                                  struct scatterlist *,
  55                                                  unsigned int))
  56 {
  57         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
  58         struct crypto_blkcipher **ctx = crypto_skcipher_ctx(tfm);
  59         struct blkcipher_desc desc = {
  60                 .tfm = *ctx,
  61                 .info = req->iv,
  62                 .flags = req->base.flags,
  63         };
  64
  65
  66         return crypt(&desc, req->dst, req->src, req->cryptlen);
  67 }
  68
  69 static int skcipher_encrypt_blkcipher(struct skcipher_request *req)
  70 {
  71         struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
  72         struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
  73         struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
  74
  75         return skcipher_crypt_blkcipher(req, alg->encrypt);
  76 }
  77
  78 static int skcipher_decrypt_blkcipher(struct skcipher_request *req)
  79 {
  80         struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
  81         struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
  82         struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
  83
  84         return skcipher_crypt_blkcipher(req, alg->decrypt);
  85 }
  86
  87 static void crypto_exit_skcipher_ops_blkcipher(struct crypto_tfm *tfm)
  88 {
  89         struct crypto_blkcipher **ctx = crypto_tfm_ctx(tfm);
  90
  91         crypto_free_blkcipher(*ctx);
  92 }
  93
  94 static int crypto_init_skcipher_ops_blkcipher(struct crypto_tfm *tfm)
  95 {
  96         struct crypto_alg *calg = tfm->__crt_alg;
  97         struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
  98         struct crypto_blkcipher **ctx = crypto_tfm_ctx(tfm);
  99         struct crypto_blkcipher *blkcipher;
 100         struct crypto_tfm *btfm;
 101
 102         if (!crypto_mod_get(calg))
 103                 return -EAGAIN;
 104
 105         btfm = __crypto_alloc_tfm(calg, CRYPTO_ALG_TYPE_BLKCIPHER,
 106                                         CRYPTO_ALG_TYPE_MASK);
 107         if (IS_ERR(btfm)) {
 108                 crypto_mod_put(calg);
 109                 return PTR_ERR(btfm);
 110         }
 111
 112         blkcipher = __crypto_blkcipher_cast(btfm);
 113         *ctx = blkcipher;
 114         tfm->exit = crypto_exit_skcipher_ops_blkcipher;
 115
 116         skcipher->setkey = skcipher_setkey_blkcipher;
 117         skcipher->encrypt = skcipher_encrypt_blkcipher;
 118         skcipher->decrypt = skcipher_decrypt_blkcipher;
 119
 120         skcipher->ivsize = crypto_blkcipher_ivsize(blkcipher);
 121         skcipher->has_setkey = calg->cra_blkcipher.max_keysize;
 122
 123         return 0;
 124 }
 125
 126 static int skcipher_setkey_ablkcipher(struct crypto_skcipher *tfm,
 127                                       const u8 *key, unsigned int keylen)
 128 {
 129         struct crypto_ablkcipher **ctx = crypto_skcipher_ctx(tfm);
 130         struct crypto_ablkcipher *ablkcipher = *ctx;
 131         int err;
 132
 133         crypto_ablkcipher_clear_flags(ablkcipher, ~0);
 134         crypto_ablkcipher_set_flags(ablkcipher,
 135                                     crypto_skcipher_get_flags(tfm) &
 136                                     CRYPTO_TFM_REQ_MASK);
 137         err = crypto_ablkcipher_setkey(ablkcipher, key, keylen);
 138         crypto_skcipher_set_flags(tfm,
 139                                   crypto_ablkcipher_get_flags(ablkcipher) &
 140                                   CRYPTO_TFM_RES_MASK);
 141
 142         return err;
 143 }
 144
 145 static int skcipher_crypt_ablkcipher(struct skcipher_request *req,
 146                                      int (*crypt)(struct ablkcipher_request *))
 147 {
 148         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 149         struct crypto_ablkcipher **ctx = crypto_skcipher_ctx(tfm);
 150         struct ablkcipher_request *subreq = skcipher_request_ctx(req);
 151
 152         ablkcipher_request_set_tfm(subreq, *ctx);
 153         ablkcipher_request_set_callback(subreq, skcipher_request_flags(req),
 154                                         req->base.complete, req->base.data);
 155         ablkcipher_request_set_crypt(subreq, req->src, req->dst, req->cryptlen,
 156                                      req->iv);
 157
 158         return crypt(subreq);
 159 }
 160
 161 static int skcipher_encrypt_ablkcipher(struct skcipher_request *req)
 162 {
 163         struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
 164         struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
 165         struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;
 166
 167         return skcipher_crypt_ablkcipher(req, alg->encrypt);
 168 }
 169
 170 static int skcipher_decrypt_ablkcipher(struct skcipher_request *req)
 171 {
 172         struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
 173         struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
 174         struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;
 175
 176         return skcipher_crypt_ablkcipher(req, alg->decrypt);
 177 }
 178
 179 static void crypto_exit_skcipher_ops_ablkcipher(struct crypto_tfm *tfm)
 180 {
 181         struct crypto_ablkcipher **ctx = crypto_tfm_ctx(tfm);
 182
 183         crypto_free_ablkcipher(*ctx);
 184 }
 185
 186 static int crypto_init_skcipher_ops_ablkcipher(struct crypto_tfm *tfm)
 187 {
 188         struct crypto_alg *calg = tfm->__crt_alg;
 189         struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
 190         struct crypto_ablkcipher **ctx = crypto_tfm_ctx(tfm);
 191         struct crypto_ablkcipher *ablkcipher;
 192         struct crypto_tfm *abtfm;
 193
 194         if (!crypto_mod_get(calg))
 195                 return -EAGAIN;
 196
 197         abtfm = __crypto_alloc_tfm(calg, 0, 0);
 198         if (IS_ERR(abtfm)) {
 199                 crypto_mod_put(calg);
 200                 return PTR_ERR(abtfm);
 201         }
 202
 203         ablkcipher = __crypto_ablkcipher_cast(abtfm);
 204         *ctx = ablkcipher;
 205         tfm->exit = crypto_exit_skcipher_ops_ablkcipher;
 206
 207         skcipher->setkey = skcipher_setkey_ablkcipher;
 208         skcipher->encrypt = skcipher_encrypt_ablkcipher;
 209         skcipher->decrypt = skcipher_decrypt_ablkcipher;
 210
 211         skcipher->ivsize = crypto_ablkcipher_ivsize(ablkcipher);
 212         skcipher->reqsize = crypto_ablkcipher_reqsize(ablkcipher) +
 213                             sizeof(struct ablkcipher_request);
 214         skcipher->has_setkey = calg->cra_ablkcipher.max_keysize;
 215
 216         return 0;
 217 }
 218
 219 static int crypto_skcipher_init_tfm(struct crypto_tfm *tfm)
 220 {
 221         if (tfm->__crt_alg->cra_type == &crypto_blkcipher_type)
 222                 return crypto_init_skcipher_ops_blkcipher(tfm);
 223
 224         BUG_ON(tfm->__crt_alg->cra_type != &crypto_ablkcipher_type &&
 225                tfm->__crt_alg->cra_type != &crypto_givcipher_type);
 226
 227         return crypto_init_skcipher_ops_ablkcipher(tfm);
 228 }
 229
 230 static const struct crypto_type crypto_skcipher_type2 = {
 231         .extsize = crypto_skcipher_extsize,
 232         .init_tfm = crypto_skcipher_init_tfm,
 233         .maskclear = ~CRYPTO_ALG_TYPE_MASK,
 234         .maskset = CRYPTO_ALG_TYPE_BLKCIPHER_MASK,
 235         .type = CRYPTO_ALG_TYPE_BLKCIPHER,
 236         .tfmsize = offsetof(struct crypto_skcipher, base),
 237 };
 238
 239 struct crypto_skcipher *crypto_alloc_skcipher(const char *alg_name,
 240                                               u32 type, u32 mask)
 241 {
 242         return crypto_alloc_tfm(alg_name, &crypto_skcipher_type2, type, mask);
 243 }
 244 EXPORT_SYMBOL_GPL(crypto_alloc_skcipher);
 245
 246 MODULE_LICENSE("GPL");
 247 MODULE_DESCRIPTION("Symmetric key cipher type");