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448 lines
11 KiB
448 lines
11 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* lib80211 crypt: host-based CCMP encryption implementation for lib80211 |
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* |
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* Copyright (c) 2003-2004, Jouni Malinen <[email protected]> |
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* Copyright (c) 2008, John W. Linville <[email protected]> |
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*/ |
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#include <linux/kernel.h> |
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#include <linux/err.h> |
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#include <linux/module.h> |
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#include <linux/init.h> |
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#include <linux/slab.h> |
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#include <linux/random.h> |
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#include <linux/skbuff.h> |
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#include <linux/netdevice.h> |
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#include <linux/if_ether.h> |
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#include <linux/if_arp.h> |
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#include <asm/string.h> |
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#include <linux/wireless.h> |
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#include <linux/ieee80211.h> |
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#include <linux/crypto.h> |
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#include <crypto/aead.h> |
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#include <net/lib80211.h> |
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MODULE_AUTHOR("Jouni Malinen"); |
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MODULE_DESCRIPTION("Host AP crypt: CCMP"); |
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MODULE_LICENSE("GPL"); |
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#define AES_BLOCK_LEN 16 |
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#define CCMP_HDR_LEN 8 |
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#define CCMP_MIC_LEN 8 |
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#define CCMP_TK_LEN 16 |
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#define CCMP_PN_LEN 6 |
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struct lib80211_ccmp_data { |
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u8 key[CCMP_TK_LEN]; |
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int key_set; |
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u8 tx_pn[CCMP_PN_LEN]; |
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u8 rx_pn[CCMP_PN_LEN]; |
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u32 dot11RSNAStatsCCMPFormatErrors; |
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u32 dot11RSNAStatsCCMPReplays; |
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u32 dot11RSNAStatsCCMPDecryptErrors; |
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int key_idx; |
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struct crypto_aead *tfm; |
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/* scratch buffers for virt_to_page() (crypto API) */ |
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u8 tx_aad[2 * AES_BLOCK_LEN]; |
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u8 rx_aad[2 * AES_BLOCK_LEN]; |
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}; |
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static void *lib80211_ccmp_init(int key_idx) |
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{ |
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struct lib80211_ccmp_data *priv; |
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priv = kzalloc(sizeof(*priv), GFP_ATOMIC); |
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if (priv == NULL) |
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goto fail; |
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priv->key_idx = key_idx; |
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priv->tfm = crypto_alloc_aead("ccm(aes)", 0, CRYPTO_ALG_ASYNC); |
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if (IS_ERR(priv->tfm)) { |
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priv->tfm = NULL; |
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goto fail; |
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} |
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return priv; |
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fail: |
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if (priv) { |
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if (priv->tfm) |
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crypto_free_aead(priv->tfm); |
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kfree(priv); |
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} |
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return NULL; |
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} |
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static void lib80211_ccmp_deinit(void *priv) |
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{ |
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struct lib80211_ccmp_data *_priv = priv; |
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if (_priv && _priv->tfm) |
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crypto_free_aead(_priv->tfm); |
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kfree(priv); |
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} |
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static int ccmp_init_iv_and_aad(const struct ieee80211_hdr *hdr, |
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const u8 *pn, u8 *iv, u8 *aad) |
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{ |
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u8 *pos, qc = 0; |
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size_t aad_len; |
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int a4_included, qc_included; |
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a4_included = ieee80211_has_a4(hdr->frame_control); |
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qc_included = ieee80211_is_data_qos(hdr->frame_control); |
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aad_len = 22; |
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if (a4_included) |
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aad_len += 6; |
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if (qc_included) { |
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pos = (u8 *) & hdr->addr4; |
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if (a4_included) |
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pos += 6; |
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qc = *pos & 0x0f; |
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aad_len += 2; |
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} |
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/* In CCM, the initial vectors (IV) used for CTR mode encryption and CBC |
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* mode authentication are not allowed to collide, yet both are derived |
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* from the same vector. We only set L := 1 here to indicate that the |
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* data size can be represented in (L+1) bytes. The CCM layer will take |
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* care of storing the data length in the top (L+1) bytes and setting |
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* and clearing the other bits as is required to derive the two IVs. |
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*/ |
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iv[0] = 0x1; |
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/* Nonce: QC | A2 | PN */ |
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iv[1] = qc; |
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memcpy(iv + 2, hdr->addr2, ETH_ALEN); |
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memcpy(iv + 8, pn, CCMP_PN_LEN); |
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/* AAD: |
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* FC with bits 4..6 and 11..13 masked to zero; 14 is always one |
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* A1 | A2 | A3 |
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* SC with bits 4..15 (seq#) masked to zero |
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* A4 (if present) |
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* QC (if present) |
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*/ |
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pos = (u8 *) hdr; |
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aad[0] = pos[0] & 0x8f; |
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aad[1] = pos[1] & 0xc7; |
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memcpy(aad + 2, hdr->addr1, 3 * ETH_ALEN); |
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pos = (u8 *) & hdr->seq_ctrl; |
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aad[20] = pos[0] & 0x0f; |
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aad[21] = 0; /* all bits masked */ |
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memset(aad + 22, 0, 8); |
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if (a4_included) |
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memcpy(aad + 22, hdr->addr4, ETH_ALEN); |
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if (qc_included) { |
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aad[a4_included ? 28 : 22] = qc; |
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/* rest of QC masked */ |
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} |
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return aad_len; |
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} |
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static int lib80211_ccmp_hdr(struct sk_buff *skb, int hdr_len, |
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u8 *aeskey, int keylen, void *priv) |
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{ |
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struct lib80211_ccmp_data *key = priv; |
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int i; |
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u8 *pos; |
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if (skb_headroom(skb) < CCMP_HDR_LEN || skb->len < hdr_len) |
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return -1; |
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if (aeskey != NULL && keylen >= CCMP_TK_LEN) |
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memcpy(aeskey, key->key, CCMP_TK_LEN); |
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pos = skb_push(skb, CCMP_HDR_LEN); |
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memmove(pos, pos + CCMP_HDR_LEN, hdr_len); |
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pos += hdr_len; |
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i = CCMP_PN_LEN - 1; |
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while (i >= 0) { |
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key->tx_pn[i]++; |
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if (key->tx_pn[i] != 0) |
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break; |
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i--; |
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} |
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*pos++ = key->tx_pn[5]; |
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*pos++ = key->tx_pn[4]; |
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*pos++ = 0; |
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*pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */ ; |
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*pos++ = key->tx_pn[3]; |
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*pos++ = key->tx_pn[2]; |
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*pos++ = key->tx_pn[1]; |
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*pos++ = key->tx_pn[0]; |
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return CCMP_HDR_LEN; |
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} |
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static int lib80211_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv) |
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{ |
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struct lib80211_ccmp_data *key = priv; |
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struct ieee80211_hdr *hdr; |
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struct aead_request *req; |
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struct scatterlist sg[2]; |
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u8 *aad = key->tx_aad; |
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u8 iv[AES_BLOCK_LEN]; |
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int len, data_len, aad_len; |
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int ret; |
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if (skb_tailroom(skb) < CCMP_MIC_LEN || skb->len < hdr_len) |
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return -1; |
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data_len = skb->len - hdr_len; |
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len = lib80211_ccmp_hdr(skb, hdr_len, NULL, 0, priv); |
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if (len < 0) |
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return -1; |
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req = aead_request_alloc(key->tfm, GFP_ATOMIC); |
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if (!req) |
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return -ENOMEM; |
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hdr = (struct ieee80211_hdr *)skb->data; |
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aad_len = ccmp_init_iv_and_aad(hdr, key->tx_pn, iv, aad); |
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skb_put(skb, CCMP_MIC_LEN); |
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sg_init_table(sg, 2); |
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sg_set_buf(&sg[0], aad, aad_len); |
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sg_set_buf(&sg[1], skb->data + hdr_len + CCMP_HDR_LEN, |
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data_len + CCMP_MIC_LEN); |
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aead_request_set_callback(req, 0, NULL, NULL); |
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aead_request_set_ad(req, aad_len); |
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aead_request_set_crypt(req, sg, sg, data_len, iv); |
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ret = crypto_aead_encrypt(req); |
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aead_request_free(req); |
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return ret; |
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} |
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/* |
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* deal with seq counter wrapping correctly. |
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* refer to timer_after() for jiffies wrapping handling |
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*/ |
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static inline int ccmp_replay_check(u8 *pn_n, u8 *pn_o) |
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{ |
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u32 iv32_n, iv16_n; |
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u32 iv32_o, iv16_o; |
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iv32_n = (pn_n[0] << 24) | (pn_n[1] << 16) | (pn_n[2] << 8) | pn_n[3]; |
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iv16_n = (pn_n[4] << 8) | pn_n[5]; |
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iv32_o = (pn_o[0] << 24) | (pn_o[1] << 16) | (pn_o[2] << 8) | pn_o[3]; |
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iv16_o = (pn_o[4] << 8) | pn_o[5]; |
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if ((s32)iv32_n - (s32)iv32_o < 0 || |
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(iv32_n == iv32_o && iv16_n <= iv16_o)) |
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return 1; |
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return 0; |
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} |
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static int lib80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv) |
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{ |
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struct lib80211_ccmp_data *key = priv; |
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u8 keyidx, *pos; |
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struct ieee80211_hdr *hdr; |
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struct aead_request *req; |
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struct scatterlist sg[2]; |
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u8 *aad = key->rx_aad; |
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u8 iv[AES_BLOCK_LEN]; |
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u8 pn[6]; |
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int aad_len, ret; |
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size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN; |
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if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) { |
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key->dot11RSNAStatsCCMPFormatErrors++; |
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return -1; |
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} |
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hdr = (struct ieee80211_hdr *)skb->data; |
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pos = skb->data + hdr_len; |
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keyidx = pos[3]; |
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if (!(keyidx & (1 << 5))) { |
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net_dbg_ratelimited("CCMP: received packet without ExtIV flag from %pM\n", |
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hdr->addr2); |
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key->dot11RSNAStatsCCMPFormatErrors++; |
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return -2; |
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} |
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keyidx >>= 6; |
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if (key->key_idx != keyidx) { |
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net_dbg_ratelimited("CCMP: RX tkey->key_idx=%d frame keyidx=%d\n", |
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key->key_idx, keyidx); |
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return -6; |
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} |
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if (!key->key_set) { |
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net_dbg_ratelimited("CCMP: received packet from %pM with keyid=%d that does not have a configured key\n", |
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hdr->addr2, keyidx); |
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return -3; |
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} |
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pn[0] = pos[7]; |
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pn[1] = pos[6]; |
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pn[2] = pos[5]; |
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pn[3] = pos[4]; |
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pn[4] = pos[1]; |
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pn[5] = pos[0]; |
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pos += 8; |
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if (ccmp_replay_check(pn, key->rx_pn)) { |
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#ifdef CONFIG_LIB80211_DEBUG |
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net_dbg_ratelimited("CCMP: replay detected: STA=%pM previous PN %02x%02x%02x%02x%02x%02x received PN %02x%02x%02x%02x%02x%02x\n", |
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hdr->addr2, |
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key->rx_pn[0], key->rx_pn[1], key->rx_pn[2], |
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key->rx_pn[3], key->rx_pn[4], key->rx_pn[5], |
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pn[0], pn[1], pn[2], pn[3], pn[4], pn[5]); |
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#endif |
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key->dot11RSNAStatsCCMPReplays++; |
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return -4; |
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} |
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req = aead_request_alloc(key->tfm, GFP_ATOMIC); |
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if (!req) |
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return -ENOMEM; |
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aad_len = ccmp_init_iv_and_aad(hdr, pn, iv, aad); |
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sg_init_table(sg, 2); |
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sg_set_buf(&sg[0], aad, aad_len); |
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sg_set_buf(&sg[1], pos, data_len); |
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aead_request_set_callback(req, 0, NULL, NULL); |
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aead_request_set_ad(req, aad_len); |
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aead_request_set_crypt(req, sg, sg, data_len, iv); |
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ret = crypto_aead_decrypt(req); |
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aead_request_free(req); |
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if (ret) { |
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net_dbg_ratelimited("CCMP: decrypt failed: STA=%pM (%d)\n", |
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hdr->addr2, ret); |
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key->dot11RSNAStatsCCMPDecryptErrors++; |
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return -5; |
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} |
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memcpy(key->rx_pn, pn, CCMP_PN_LEN); |
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/* Remove hdr and MIC */ |
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memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len); |
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skb_pull(skb, CCMP_HDR_LEN); |
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skb_trim(skb, skb->len - CCMP_MIC_LEN); |
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return keyidx; |
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} |
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static int lib80211_ccmp_set_key(void *key, int len, u8 * seq, void *priv) |
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{ |
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struct lib80211_ccmp_data *data = priv; |
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int keyidx; |
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struct crypto_aead *tfm = data->tfm; |
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keyidx = data->key_idx; |
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memset(data, 0, sizeof(*data)); |
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data->key_idx = keyidx; |
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data->tfm = tfm; |
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if (len == CCMP_TK_LEN) { |
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memcpy(data->key, key, CCMP_TK_LEN); |
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data->key_set = 1; |
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if (seq) { |
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data->rx_pn[0] = seq[5]; |
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data->rx_pn[1] = seq[4]; |
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data->rx_pn[2] = seq[3]; |
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data->rx_pn[3] = seq[2]; |
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data->rx_pn[4] = seq[1]; |
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data->rx_pn[5] = seq[0]; |
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} |
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if (crypto_aead_setauthsize(data->tfm, CCMP_MIC_LEN) || |
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crypto_aead_setkey(data->tfm, data->key, CCMP_TK_LEN)) |
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return -1; |
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} else if (len == 0) |
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data->key_set = 0; |
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else |
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return -1; |
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return 0; |
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} |
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static int lib80211_ccmp_get_key(void *key, int len, u8 * seq, void *priv) |
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{ |
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struct lib80211_ccmp_data *data = priv; |
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if (len < CCMP_TK_LEN) |
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return -1; |
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if (!data->key_set) |
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return 0; |
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memcpy(key, data->key, CCMP_TK_LEN); |
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if (seq) { |
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seq[0] = data->tx_pn[5]; |
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seq[1] = data->tx_pn[4]; |
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seq[2] = data->tx_pn[3]; |
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seq[3] = data->tx_pn[2]; |
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seq[4] = data->tx_pn[1]; |
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seq[5] = data->tx_pn[0]; |
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} |
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return CCMP_TK_LEN; |
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} |
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static void lib80211_ccmp_print_stats(struct seq_file *m, void *priv) |
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{ |
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struct lib80211_ccmp_data *ccmp = priv; |
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seq_printf(m, |
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"key[%d] alg=CCMP key_set=%d " |
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"tx_pn=%02x%02x%02x%02x%02x%02x " |
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"rx_pn=%02x%02x%02x%02x%02x%02x " |
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"format_errors=%d replays=%d decrypt_errors=%d\n", |
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ccmp->key_idx, ccmp->key_set, |
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ccmp->tx_pn[0], ccmp->tx_pn[1], ccmp->tx_pn[2], |
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ccmp->tx_pn[3], ccmp->tx_pn[4], ccmp->tx_pn[5], |
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ccmp->rx_pn[0], ccmp->rx_pn[1], ccmp->rx_pn[2], |
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ccmp->rx_pn[3], ccmp->rx_pn[4], ccmp->rx_pn[5], |
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ccmp->dot11RSNAStatsCCMPFormatErrors, |
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ccmp->dot11RSNAStatsCCMPReplays, |
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ccmp->dot11RSNAStatsCCMPDecryptErrors); |
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} |
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static struct lib80211_crypto_ops lib80211_crypt_ccmp = { |
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.name = "CCMP", |
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.init = lib80211_ccmp_init, |
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.deinit = lib80211_ccmp_deinit, |
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.encrypt_mpdu = lib80211_ccmp_encrypt, |
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.decrypt_mpdu = lib80211_ccmp_decrypt, |
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.encrypt_msdu = NULL, |
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.decrypt_msdu = NULL, |
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.set_key = lib80211_ccmp_set_key, |
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.get_key = lib80211_ccmp_get_key, |
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.print_stats = lib80211_ccmp_print_stats, |
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.extra_mpdu_prefix_len = CCMP_HDR_LEN, |
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.extra_mpdu_postfix_len = CCMP_MIC_LEN, |
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.owner = THIS_MODULE, |
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}; |
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static int __init lib80211_crypto_ccmp_init(void) |
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{ |
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return lib80211_register_crypto_ops(&lib80211_crypt_ccmp); |
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} |
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static void __exit lib80211_crypto_ccmp_exit(void) |
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{ |
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lib80211_unregister_crypto_ops(&lib80211_crypt_ccmp); |
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} |
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module_init(lib80211_crypto_ccmp_init); |
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module_exit(lib80211_crypto_ccmp_exit);
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