// SPDX-License-Identifier: GPL-2.0-only

  /*
   * AES-GMAC for IEEE 802.11 BIP-GMAC-128 and BIP-GMAC-256
   * Copyright 2015, Qualcomm Atheros, Inc.

   */
  
  #include <linux/kernel.h>
  #include <linux/types.h>

  #include <linux/err.h>

  #include <crypto/aead.h>

  #include <crypto/aes.h>
  
  #include <net/mac80211.h>
  #include "key.h"
  #include "aes_gmac.h"

  int ieee80211_aes_gmac(struct crypto_aead *tfm, const u8 *aad, u8 *nonce,
  		       const u8 *data, size_t data_len, u8 *mic)
  {

  	struct scatterlist sg[5];

  	u8 *zero, *__aad, iv[AES_BLOCK_SIZE];
  	struct aead_request *aead_req;
  	int reqsize = sizeof(*aead_req) + crypto_aead_reqsize(tfm);

  	const __le16 *fc;

  
  	if (data_len < GMAC_MIC_LEN)
  		return -EINVAL;

  	aead_req = kzalloc(reqsize + GMAC_MIC_LEN + GMAC_AAD_LEN, GFP_ATOMIC);
  	if (!aead_req)
  		return -ENOMEM;
  
  	zero = (u8 *)aead_req + reqsize;
  	__aad = zero + GMAC_MIC_LEN;
  	memcpy(__aad, aad, GMAC_AAD_LEN);

  	fc = (const __le16 *)aad;
  	if (ieee80211_is_beacon(*fc)) {
  		/* mask Timestamp field to zero */
  		sg_init_table(sg, 5);
  		sg_set_buf(&sg[0], __aad, GMAC_AAD_LEN);
  		sg_set_buf(&sg[1], zero, 8);
  		sg_set_buf(&sg[2], data + 8, data_len - 8 - GMAC_MIC_LEN);
  		sg_set_buf(&sg[3], zero, GMAC_MIC_LEN);
  		sg_set_buf(&sg[4], mic, GMAC_MIC_LEN);
  	} else {
  		sg_init_table(sg, 4);
  		sg_set_buf(&sg[0], __aad, GMAC_AAD_LEN);
  		sg_set_buf(&sg[1], data, data_len - GMAC_MIC_LEN);
  		sg_set_buf(&sg[2], zero, GMAC_MIC_LEN);
  		sg_set_buf(&sg[3], mic, GMAC_MIC_LEN);
  	}

  
  	memcpy(iv, nonce, GMAC_NONCE_LEN);
  	memset(iv + GMAC_NONCE_LEN, 0, sizeof(iv) - GMAC_NONCE_LEN);
  	iv[AES_BLOCK_SIZE - 1] = 0x01;

  	aead_request_set_tfm(aead_req, tfm);

  	aead_request_set_crypt(aead_req, sg, sg, 0, iv);

  	aead_request_set_ad(aead_req, GMAC_AAD_LEN + data_len);

  
  	crypto_aead_encrypt(aead_req);

  	kfree_sensitive(aead_req);

  
  	return 0;
  }
  
  struct crypto_aead *ieee80211_aes_gmac_key_setup(const u8 key[],
  						 size_t key_len)
  {
  	struct crypto_aead *tfm;
  	int err;
  
  	tfm = crypto_alloc_aead("gcm(aes)", 0, CRYPTO_ALG_ASYNC);
  	if (IS_ERR(tfm))
  		return tfm;
  
  	err = crypto_aead_setkey(tfm, key, key_len);
  	if (!err)

  		err = crypto_aead_setauthsize(tfm, GMAC_MIC_LEN);

  	if (!err)
  		return tfm;

  
  	crypto_free_aead(tfm);
  	return ERR_PTR(err);
  }
  
  void ieee80211_aes_gmac_key_free(struct crypto_aead *tfm)
  {
  	crypto_free_aead(tfm);
  }