// SPDX-License-Identifier: GPL-2.0-only
/*
 * libipw crypt: host-based CCMP encryption implementation for libipw
 *
 * Copyright (c) 2003-2004, Jouni Malinen <j@w1.fi>
 * Copyright (c) 2008, John W. Linville <linville@tuxdriver.com>
 */

#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/if_ether.h>
#include <linux/if_arp.h>
#include <asm/string.h>
#include <linux/wireless.h>
#include <linux/ieee80211.h>
#include <linux/crypto.h>
#include <crypto/aead.h>
#include "libipw.h"

#define AES_BLOCK_LEN 16
#define CCMP_HDR_LEN 8
#define CCMP_MIC_LEN 8
#define CCMP_TK_LEN 16
#define CCMP_PN_LEN 6

struct libipw_ccmp_data {
        u8 key[CCMP_TK_LEN];
        int key_set;

        u8 tx_pn[CCMP_PN_LEN];
        u8 rx_pn[CCMP_PN_LEN];

        u32 dot11RSNAStatsCCMPFormatErrors;
        u32 dot11RSNAStatsCCMPReplays;
        u32 dot11RSNAStatsCCMPDecryptErrors;

        int key_idx;

        struct crypto_aead *tfm;

        /* scratch buffers for virt_to_page() (crypto API) */
        u8 tx_aad[2 * AES_BLOCK_LEN];
        u8 rx_aad[2 * AES_BLOCK_LEN];
};

static void *libipw_ccmp_init(int key_idx)
{
        struct libipw_ccmp_data *priv;

        priv = kzalloc_obj(*priv, GFP_ATOMIC);
        if (priv == NULL)
                goto fail;
        priv->key_idx = key_idx;

        priv->tfm = crypto_alloc_aead("ccm(aes)", 0, CRYPTO_ALG_ASYNC);
        if (IS_ERR(priv->tfm)) {
                priv->tfm = NULL;
                goto fail;
        }

        return priv;

      fail:
        if (priv) {
                if (priv->tfm)
                        crypto_free_aead(priv->tfm);
                kfree(priv);
        }

        return NULL;
}

static void libipw_ccmp_deinit(void *priv)
{
        struct libipw_ccmp_data *_priv = priv;
        if (_priv && _priv->tfm)
                crypto_free_aead(_priv->tfm);
        kfree(priv);
}

static int ccmp_init_iv_and_aad(const struct ieee80211_hdr *hdr,
                                const u8 *pn, u8 *iv, u8 *aad)
{
        u8 *pos, qc = 0;
        size_t aad_len;
        int a4_included, qc_included;

        a4_included = ieee80211_has_a4(hdr->frame_control);
        qc_included = ieee80211_is_data_qos(hdr->frame_control);

        aad_len = 22;
        if (a4_included)
                aad_len += 6;
        if (qc_included) {
                pos = (u8 *) & hdr->addr4;
                if (a4_included)
                        pos += 6;
                qc = *pos & 0x0f;
                aad_len += 2;
        }

        /* In CCM, the initial vectors (IV) used for CTR mode encryption and CBC
         * mode authentication are not allowed to collide, yet both are derived
         * from the same vector. We only set L := 1 here to indicate that the
         * data size can be represented in (L+1) bytes. The CCM layer will take
         * care of storing the data length in the top (L+1) bytes and setting
         * and clearing the other bits as is required to derive the two IVs.
         */
        iv[0] = 0x1;

        /* Nonce: QC | A2 | PN */
        iv[1] = qc;
        memcpy(iv + 2, hdr->addr2, ETH_ALEN);
        memcpy(iv + 8, pn, CCMP_PN_LEN);

        /* AAD:
         * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
         * A1 | A2 | A3
         * SC with bits 4..15 (seq#) masked to zero
         * A4 (if present)
         * QC (if present)
         */
        pos = (u8 *) hdr;
        aad[0] = pos[0] & 0x8f;
        aad[1] = pos[1] & 0xc7;
        memcpy(aad + 2, &hdr->addrs, 3 * ETH_ALEN);
        pos = (u8 *) & hdr->seq_ctrl;
        aad[20] = pos[0] & 0x0f;
        aad[21] = 0;            /* all bits masked */
        memset(aad + 22, 0, 8);
        if (a4_included)
                memcpy(aad + 22, hdr->addr4, ETH_ALEN);
        if (qc_included) {
                aad[a4_included ? 28 : 22] = qc;
                /* rest of QC masked */
        }
        return aad_len;
}

static int libipw_ccmp_hdr(struct sk_buff *skb, int hdr_len,
                              u8 *aeskey, int keylen, void *priv)
{
        struct libipw_ccmp_data *key = priv;
        int i;
        u8 *pos;

        if (skb_headroom(skb) < CCMP_HDR_LEN || skb->len < hdr_len)
                return -1;

        if (aeskey != NULL && keylen >= CCMP_TK_LEN)
                memcpy(aeskey, key->key, CCMP_TK_LEN);

        pos = skb_push(skb, CCMP_HDR_LEN);
        memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
        pos += hdr_len;

        i = CCMP_PN_LEN - 1;
        while (i >= 0) {
                key->tx_pn[i]++;
                if (key->tx_pn[i] != 0)
                        break;
                i--;
        }

        *pos++ = key->tx_pn[5];
        *pos++ = key->tx_pn[4];
        *pos++ = 0;
        *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */ ;
        *pos++ = key->tx_pn[3];
        *pos++ = key->tx_pn[2];
        *pos++ = key->tx_pn[1];
        *pos++ = key->tx_pn[0];

        return CCMP_HDR_LEN;
}

static int libipw_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
{
        struct libipw_ccmp_data *key = priv;
        struct ieee80211_hdr *hdr;
        struct aead_request *req;
        struct scatterlist sg[2];
        u8 *aad = key->tx_aad;
        u8 iv[AES_BLOCK_LEN];
        int len, data_len, aad_len;
        int ret;

        if (skb_tailroom(skb) < CCMP_MIC_LEN || skb->len < hdr_len)
                return -1;

        data_len = skb->len - hdr_len;
        len = libipw_ccmp_hdr(skb, hdr_len, NULL, 0, priv);
        if (len < 0)
                return -1;

        req = aead_request_alloc(key->tfm, GFP_ATOMIC);
        if (!req)
                return -ENOMEM;

        hdr = (struct ieee80211_hdr *)skb->data;
        aad_len = ccmp_init_iv_and_aad(hdr, key->tx_pn, iv, aad);

        skb_put(skb, CCMP_MIC_LEN);

        sg_init_table(sg, 2);
        sg_set_buf(&sg[0], aad, aad_len);
        sg_set_buf(&sg[1], skb->data + hdr_len + CCMP_HDR_LEN,
                   data_len + CCMP_MIC_LEN);

        aead_request_set_callback(req, 0, NULL, NULL);
        aead_request_set_ad(req, aad_len);
        aead_request_set_crypt(req, sg, sg, data_len, iv);

        ret = crypto_aead_encrypt(req);
        aead_request_free(req);

        return ret;
}

/*
 * deal with seq counter wrapping correctly.
 * refer to timer_after() for jiffies wrapping handling
 */
static inline int ccmp_replay_check(u8 *pn_n, u8 *pn_o)
{
        u32 iv32_n, iv16_n;
        u32 iv32_o, iv16_o;

        iv32_n = (pn_n[0] << 24) | (pn_n[1] << 16) | (pn_n[2] << 8) | pn_n[3];
        iv16_n = (pn_n[4] << 8) | pn_n[5];

        iv32_o = (pn_o[0] << 24) | (pn_o[1] << 16) | (pn_o[2] << 8) | pn_o[3];
        iv16_o = (pn_o[4] << 8) | pn_o[5];

        if ((s32)iv32_n - (s32)iv32_o < 0 ||
            (iv32_n == iv32_o && iv16_n <= iv16_o))
                return 1;
        return 0;
}

static int libipw_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
{
        struct libipw_ccmp_data *key = priv;
        u8 keyidx, *pos;
        struct ieee80211_hdr *hdr;
        struct aead_request *req;
        struct scatterlist sg[2];
        u8 *aad = key->rx_aad;
        u8 iv[AES_BLOCK_LEN];
        u8 pn[6];
        int aad_len, ret;
        size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN;

        if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
                key->dot11RSNAStatsCCMPFormatErrors++;
                return -1;
        }

        hdr = (struct ieee80211_hdr *)skb->data;
        pos = skb->data + hdr_len;
        keyidx = pos[3];
        if (!(keyidx & (1 << 5))) {
                net_dbg_ratelimited("CCMP: received packet without ExtIV flag from %pM\n",
                                    hdr->addr2);
                key->dot11RSNAStatsCCMPFormatErrors++;
                return -2;
        }
        keyidx >>= 6;
        if (key->key_idx != keyidx) {
                net_dbg_ratelimited("CCMP: RX tkey->key_idx=%d frame keyidx=%d\n",
                                    key->key_idx, keyidx);
                return -6;
        }
        if (!key->key_set) {
                net_dbg_ratelimited("CCMP: received packet from %pM with keyid=%d that does not have a configured key\n",
                                    hdr->addr2, keyidx);
                return -3;
        }

        pn[0] = pos[7];
        pn[1] = pos[6];
        pn[2] = pos[5];
        pn[3] = pos[4];
        pn[4] = pos[1];
        pn[5] = pos[0];
        pos += 8;

        if (ccmp_replay_check(pn, key->rx_pn)) {
#ifdef CONFIG_LIBIPW_DEBUG
                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",
                                    hdr->addr2,
                                    key->rx_pn[0], key->rx_pn[1], key->rx_pn[2],
                                    key->rx_pn[3], key->rx_pn[4], key->rx_pn[5],
                                    pn[0], pn[1], pn[2], pn[3], pn[4], pn[5]);
#endif
                key->dot11RSNAStatsCCMPReplays++;
                return -4;
        }

        req = aead_request_alloc(key->tfm, GFP_ATOMIC);
        if (!req)
                return -ENOMEM;

        aad_len = ccmp_init_iv_and_aad(hdr, pn, iv, aad);

        sg_init_table(sg, 2);
        sg_set_buf(&sg[0], aad, aad_len);
        sg_set_buf(&sg[1], pos, data_len);

        aead_request_set_callback(req, 0, NULL, NULL);
        aead_request_set_ad(req, aad_len);
        aead_request_set_crypt(req, sg, sg, data_len, iv);

        ret = crypto_aead_decrypt(req);
        aead_request_free(req);

        if (ret) {
                net_dbg_ratelimited("CCMP: decrypt failed: STA=%pM (%d)\n",
                                    hdr->addr2, ret);
                key->dot11RSNAStatsCCMPDecryptErrors++;
                return -5;
        }

        memcpy(key->rx_pn, pn, CCMP_PN_LEN);

        /* Remove hdr and MIC */
        memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
        skb_pull(skb, CCMP_HDR_LEN);
        skb_trim(skb, skb->len - CCMP_MIC_LEN);

        return keyidx;
}

static int libipw_ccmp_set_key(void *key, int len, u8 * seq, void *priv)
{
        struct libipw_ccmp_data *data = priv;
        int keyidx;
        struct crypto_aead *tfm = data->tfm;

        keyidx = data->key_idx;
        memset(data, 0, sizeof(*data));
        data->key_idx = keyidx;
        data->tfm = tfm;
        if (len == CCMP_TK_LEN) {
                memcpy(data->key, key, CCMP_TK_LEN);
                data->key_set = 1;
                if (seq) {
                        data->rx_pn[0] = seq[5];
                        data->rx_pn[1] = seq[4];
                        data->rx_pn[2] = seq[3];
                        data->rx_pn[3] = seq[2];
                        data->rx_pn[4] = seq[1];
                        data->rx_pn[5] = seq[0];
                }
                if (crypto_aead_setauthsize(data->tfm, CCMP_MIC_LEN) ||
                    crypto_aead_setkey(data->tfm, data->key, CCMP_TK_LEN))
                        return -1;
        } else if (len == 0)
                data->key_set = 0;
        else
                return -1;

        return 0;
}

static int libipw_ccmp_get_key(void *key, int len, u8 * seq, void *priv)
{
        struct libipw_ccmp_data *data = priv;

        if (len < CCMP_TK_LEN)
                return -1;

        if (!data->key_set)
                return 0;
        memcpy(key, data->key, CCMP_TK_LEN);

        if (seq) {
                seq[0] = data->tx_pn[5];
                seq[1] = data->tx_pn[4];
                seq[2] = data->tx_pn[3];
                seq[3] = data->tx_pn[2];
                seq[4] = data->tx_pn[1];
                seq[5] = data->tx_pn[0];
        }

        return CCMP_TK_LEN;
}

static void libipw_ccmp_print_stats(struct seq_file *m, void *priv)
{
        struct libipw_ccmp_data *ccmp = priv;

        seq_printf(m,
                   "key[%d] alg=CCMP key_set=%d "
                   "tx_pn=%02x%02x%02x%02x%02x%02x "
                   "rx_pn=%02x%02x%02x%02x%02x%02x "
                   "format_errors=%d replays=%d decrypt_errors=%d\n",
                   ccmp->key_idx, ccmp->key_set,
                   ccmp->tx_pn[0], ccmp->tx_pn[1], ccmp->tx_pn[2],
                   ccmp->tx_pn[3], ccmp->tx_pn[4], ccmp->tx_pn[5],
                   ccmp->rx_pn[0], ccmp->rx_pn[1], ccmp->rx_pn[2],
                   ccmp->rx_pn[3], ccmp->rx_pn[4], ccmp->rx_pn[5],
                   ccmp->dot11RSNAStatsCCMPFormatErrors,
                   ccmp->dot11RSNAStatsCCMPReplays,
                   ccmp->dot11RSNAStatsCCMPDecryptErrors);
}

static const struct libipw_crypto_ops libipw_crypt_ccmp = {
        .name = "CCMP",
        .init = libipw_ccmp_init,
        .deinit = libipw_ccmp_deinit,
        .encrypt_mpdu = libipw_ccmp_encrypt,
        .decrypt_mpdu = libipw_ccmp_decrypt,
        .encrypt_msdu = NULL,
        .decrypt_msdu = NULL,
        .set_key = libipw_ccmp_set_key,
        .get_key = libipw_ccmp_get_key,
        .print_stats = libipw_ccmp_print_stats,
        .extra_mpdu_prefix_len = CCMP_HDR_LEN,
        .extra_mpdu_postfix_len = CCMP_MIC_LEN,
        .owner = THIS_MODULE,
};

int __init libipw_crypto_ccmp_init(void)
{
        return libipw_register_crypto_ops(&libipw_crypt_ccmp);
}

void libipw_crypto_ccmp_exit(void)
{
        libipw_unregister_crypto_ops(&libipw_crypt_ccmp);
}