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![Ard Biesheuvel](/assets/img/avatar_default.png)
Instead of open coding the CCM aead mode in the driver, and invoking the AES block cipher block by block, use a ccm(aes) aead transform which already encapsulates this functionality. This is a cleaner use of the crypto API, and permits optimized implementations to be used, which are typically much faster and deal more efficiently with the SIMD register file, which usually needs to be preserved/restored in order to use special AES instructions. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Link: https://lore.kernel.org/r/20190617091901.7063-1-ard.biesheuvel@linaro.org Signed-off-by: Johannes Berg <johannes.berg@intel.com>
448 lines
11 KiB
C
448 lines
11 KiB
C
// 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 <j@w1.fi>
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* Copyright (c) 2008, John W. Linville <linville@tuxdriver.com>
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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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