net/mac80211/aes_gcm.c

   1 /*
   2  * Copyright 2014-2015, Qualcomm Atheros, Inc.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/types.h>
  11 #include <linux/err.h>
  12 #include <crypto/aead.h>
  13
  14 #include <net/mac80211.h>
  15 #include "key.h"
  16 #include "aes_gcm.h"
  17
  18 int ieee80211_aes_gcm_encrypt(struct crypto_aead *tfm, u8 *j_0, u8 *aad,
  19                               u8 *data, size_t data_len, u8 *mic)
  20 {
  21         struct scatterlist sg[3];
  22         struct aead_request *aead_req;
  23         int reqsize = sizeof(*aead_req) + crypto_aead_reqsize(tfm);
  24         u8 *__aad;
  25
  26         aead_req = kzalloc(reqsize + GCM_AAD_LEN, GFP_ATOMIC);
  27         if (!aead_req)
  28                 return -ENOMEM;
  29
  30         __aad = (u8 *)aead_req + reqsize;
  31         memcpy(__aad, aad, GCM_AAD_LEN);
  32
  33         sg_init_table(sg, 3);
  34         sg_set_buf(&sg[0], &__aad[2], be16_to_cpup((__be16 *)__aad));
  35         sg_set_buf(&sg[1], data, data_len);
  36         sg_set_buf(&sg[2], mic, IEEE80211_GCMP_MIC_LEN);
  37
  38         aead_request_set_tfm(aead_req, tfm);
  39         aead_request_set_crypt(aead_req, sg, sg, data_len, j_0);
  40         aead_request_set_ad(aead_req, sg[0].length);
  41
  42         crypto_aead_encrypt(aead_req);
  43         kzfree(aead_req);
  44         return 0;
  45 }
  46
  47 int ieee80211_aes_gcm_decrypt(struct crypto_aead *tfm, u8 *j_0, u8 *aad,
  48                               u8 *data, size_t data_len, u8 *mic)
  49 {
  50         struct scatterlist sg[3];
  51         struct aead_request *aead_req;
  52         int reqsize = sizeof(*aead_req) + crypto_aead_reqsize(tfm);
  53         u8 *__aad;
  54         int err;
  55
  56         if (data_len == 0)
  57                 return -EINVAL;
  58
  59         aead_req = kzalloc(reqsize + GCM_AAD_LEN, GFP_ATOMIC);
  60         if (!aead_req)
  61                 return -ENOMEM;
  62
  63         __aad = (u8 *)aead_req + reqsize;
  64         memcpy(__aad, aad, GCM_AAD_LEN);
  65
  66         sg_init_table(sg, 3);
  67         sg_set_buf(&sg[0], &__aad[2], be16_to_cpup((__be16 *)__aad));
  68         sg_set_buf(&sg[1], data, data_len);
  69         sg_set_buf(&sg[2], mic, IEEE80211_GCMP_MIC_LEN);
  70
  71         aead_request_set_tfm(aead_req, tfm);
  72         aead_request_set_crypt(aead_req, sg, sg,
  73                                data_len + IEEE80211_GCMP_MIC_LEN, j_0);
  74         aead_request_set_ad(aead_req, sg[0].length);
  75
  76         err = crypto_aead_decrypt(aead_req);
  77         kzfree(aead_req);
  78
  79         return err;
  80 }
  81
  82 struct crypto_aead *ieee80211_aes_gcm_key_setup_encrypt(const u8 key[],
  83                                                         size_t key_len)
  84 {
  85         struct crypto_aead *tfm;
  86         int err;
  87
  88         tfm = crypto_alloc_aead("gcm(aes)", 0, CRYPTO_ALG_ASYNC);
  89         if (IS_ERR(tfm))
  90                 return tfm;
  91
  92         err = crypto_aead_setkey(tfm, key, key_len);
  93         if (err)
  94                 goto free_aead;
  95         err = crypto_aead_setauthsize(tfm, IEEE80211_GCMP_MIC_LEN);
  96         if (err)
  97                 goto free_aead;
  98
  99         return tfm;
 100
 101 free_aead:
 102         crypto_free_aead(tfm);
 103         return ERR_PTR(err);
 104 }
 105
 106 void ieee80211_aes_gcm_key_free(struct crypto_aead *tfm)
 107 {
 108         crypto_free_aead(tfm);
 109 }