/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2001 Atsushi Onoe
 * Copyright (c) 2002-2008 Sam Leffler, Errno Consulting
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
/*
 * IEEE 802.11 generic crypto support.
 */
#include "opt_wlan.h"

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>   

#include <sys/socket.h>

#include <net/if.h>
#include <net/if_media.h>
#include <net/ethernet.h>               /* XXX ETHER_HDR_LEN */

#include <net80211/ieee80211_var.h>

MALLOC_DEFINE(M_80211_CRYPTO, "80211crypto", "802.11 crypto state");

static  int _ieee80211_crypto_delkey(struct ieee80211vap *,
                struct ieee80211_key *);

/*
 * Table of registered cipher modules.
 */
static  const struct ieee80211_cipher *ciphers[IEEE80211_CIPHER_MAX];

/*
 * Default "null" key management routines.
 */
static int
null_key_alloc(struct ieee80211vap *vap, struct ieee80211_key *k,
        ieee80211_keyix *keyix, ieee80211_keyix *rxkeyix)
{

        if (!ieee80211_is_key_global(vap, k)) {
                /*
                 * Not in the global key table, the driver should handle this
                 * by allocating a slot in the h/w key table/cache.  In
                 * lieu of that return key slot 0 for any unicast key
                 * request.  We disallow the request if this is a group key.
                 * This default policy does the right thing for legacy hardware
                 * with a 4 key table.  It also handles devices that pass
                 * packets through untouched when marked with the WEP bit
                 * and key index 0.
                 */
                if (k->wk_flags & IEEE80211_KEY_GROUP)
                        return 0;
                *keyix = 0;     /* NB: use key index 0 for ucast key */
        } else {
                *keyix = ieee80211_crypto_get_key_wepidx(vap, k);
        }
        *rxkeyix = IEEE80211_KEYIX_NONE;        /* XXX maybe *keyix? */
        return 1;
}
static int
null_key_delete(struct ieee80211vap *vap, const struct ieee80211_key *k)
{
        return 1;
}
static  int
null_key_set(struct ieee80211vap *vap, const struct ieee80211_key *k)
{
        return 1;
}
static void null_key_update(struct ieee80211vap *vap) {}

/*
 * Write-arounds for common operations.
 */
static __inline void
cipher_detach(struct ieee80211_key *key)
{
        key->wk_cipher->ic_detach(key);
}

static __inline void *
cipher_attach(struct ieee80211vap *vap, struct ieee80211_key *key)
{
        return key->wk_cipher->ic_attach(vap, key);
}

/* 
 * Wrappers for driver key management methods.
 */
static __inline int
dev_key_alloc(struct ieee80211vap *vap,
        struct ieee80211_key *key,
        ieee80211_keyix *keyix, ieee80211_keyix *rxkeyix)
{
        return vap->iv_key_alloc(vap, key, keyix, rxkeyix);
}

static __inline int
dev_key_delete(struct ieee80211vap *vap,
        const struct ieee80211_key *key)
{
        return vap->iv_key_delete(vap, key);
}

static __inline int
dev_key_set(struct ieee80211vap *vap, const struct ieee80211_key *key)
{
        return vap->iv_key_set(vap, key);
}

/*
 * Setup crypto support for a device/shared instance.
 */
void
ieee80211_crypto_attach(struct ieee80211com *ic)
{
        /* NB: we assume everything is pre-zero'd */
        ciphers[IEEE80211_CIPHER_NONE] = &ieee80211_cipher_none;

        /*
         * Default set of net80211 supported ciphers.
         *
         * These are the default set that all drivers are expected to
         * support, either/or in hardware and software.
         *
         * Drivers can add their own support to this and the
         * hardware cipher list (ic_cryptocaps.)
         */
        ic->ic_sw_cryptocaps = IEEE80211_CRYPTO_WEP |
            IEEE80211_CRYPTO_TKIP | IEEE80211_CRYPTO_AES_CCM;

        /*
         * Default set of key management types supported by net80211.
         *
         * These are supported by software net80211 and announced/
         * driven by hostapd + wpa_supplicant.
         *
         * Drivers doing full supplicant offload must not set
         * anything here.
         *
         * Note that IEEE80211_C_WPA1 and IEEE80211_C_WPA2 are the
         * "old" style way of drivers announcing key management
         * capabilities.  There are many, many more key management
         * suites in 802.11-2016 (see 9.4.2.25.3 - AKM suites.)
         * For now they still need to be set - these flags are checked
         * when assembling a beacon to reserve space for the WPA
         * vendor IE (WPA 1) and RSN IE (WPA 2).
         */
        ic->ic_sw_keymgmtcaps = 0;
}

/*
 * Teardown crypto support.
 */
void
ieee80211_crypto_detach(struct ieee80211com *ic)
{
}

/*
 * Set the supported ciphers for software encryption.
 */
void
ieee80211_crypto_set_supported_software_ciphers(struct ieee80211com *ic,
    uint32_t cipher_set)
{
        ic->ic_sw_cryptocaps = cipher_set;
}

/*
 * Set the supported ciphers for hardware encryption.
 */
void
ieee80211_crypto_set_supported_hardware_ciphers(struct ieee80211com *ic,
    uint32_t cipher_set)
{
        ic->ic_cryptocaps = cipher_set;
}

/*
 * Set the supported software key management by the driver.
 *
 * These are the key management suites that are supported via
 * the driver via hostapd/wpa_supplicant.
 *
 * Key management which is completely offloaded (ie, the supplicant
 * runs in hardware/firmware) must not be set here.
 */
void
ieee80211_crypto_set_supported_driver_keymgmt(struct ieee80211com *ic,
    uint32_t keymgmt_set)
{

        ic->ic_sw_keymgmtcaps = keymgmt_set;
}

/*
 * Setup crypto support for a vap.
 */
void
ieee80211_crypto_vattach(struct ieee80211vap *vap)
{
        int i;

        /* NB: we assume everything is pre-zero'd */
        vap->iv_max_keyix = IEEE80211_WEP_NKID;
        vap->iv_def_txkey = IEEE80211_KEYIX_NONE;
        for (i = 0; i < IEEE80211_WEP_NKID; i++)
                ieee80211_crypto_resetkey(vap, &vap->iv_nw_keys[i],
                        IEEE80211_KEYIX_NONE);
        /*
         * Initialize the driver key support routines to noop entries.
         * This is useful especially for the cipher test modules.
         */
        vap->iv_key_alloc = null_key_alloc;
        vap->iv_key_set = null_key_set;
        vap->iv_key_delete = null_key_delete;
        vap->iv_key_update_begin = null_key_update;
        vap->iv_key_update_end = null_key_update;
}

/*
 * Teardown crypto support for a vap.
 */
void
ieee80211_crypto_vdetach(struct ieee80211vap *vap)
{
        ieee80211_crypto_delglobalkeys(vap);
}

/*
 * Register a crypto cipher module.
 */
void
ieee80211_crypto_register(const struct ieee80211_cipher *cip)
{
        if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) {
                net80211_printf("%s: cipher %s has an invalid cipher index %u\n",
                        __func__, cip->ic_name, cip->ic_cipher);
                return;
        }
        if (ciphers[cip->ic_cipher] != NULL && ciphers[cip->ic_cipher] != cip) {
                net80211_printf("%s: cipher %s registered with a different template\n",
                        __func__, cip->ic_name);
                return;
        }
        ciphers[cip->ic_cipher] = cip;
}

/*
 * Unregister a crypto cipher module.
 */
void
ieee80211_crypto_unregister(const struct ieee80211_cipher *cip)
{
        if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) {
                net80211_printf("%s: cipher %s has an invalid cipher index %u\n",
                        __func__, cip->ic_name, cip->ic_cipher);
                return;
        }
        if (ciphers[cip->ic_cipher] != NULL && ciphers[cip->ic_cipher] != cip) {
                net80211_printf("%s: cipher %s registered with a different template\n",
                        __func__, cip->ic_name);
                return;
        }
        /* NB: don't complain about not being registered */
        /* XXX disallow if references */
        ciphers[cip->ic_cipher] = NULL;
}

int
ieee80211_crypto_available(u_int cipher)
{
        return cipher < IEEE80211_CIPHER_MAX && ciphers[cipher] != NULL;
}

/* XXX well-known names! */
static const char *cipher_modnames[IEEE80211_CIPHER_MAX] = {
        [IEEE80211_CIPHER_WEP]     = "wlan_wep",
        [IEEE80211_CIPHER_TKIP]    = "wlan_tkip",
        [IEEE80211_CIPHER_AES_OCB] = "wlan_aes_ocb",
        [IEEE80211_CIPHER_AES_CCM] = "wlan_ccmp",
        [IEEE80211_CIPHER_TKIPMIC] = "#4",      /* NB: reserved */
        [IEEE80211_CIPHER_CKIP]    = "wlan_ckip",
        [IEEE80211_CIPHER_NONE]    = "wlan_none",
        [IEEE80211_CIPHER_AES_CCM_256] = "wlan_ccmp",
        [IEEE80211_CIPHER_BIP_CMAC_128] = "wlan_bip_cmac",
        [IEEE80211_CIPHER_BIP_CMAC_256] = "wlan_bip_cmac",
        [IEEE80211_CIPHER_BIP_GMAC_128] = "wlan_bip_gmac",
        [IEEE80211_CIPHER_BIP_GMAC_256] = "wlan_bip_gmac",
        [IEEE80211_CIPHER_AES_GCM_128]  = "wlan_gcmp",
        [IEEE80211_CIPHER_AES_GCM_256]  = "wlan_gcmp",
};

/* NB: there must be no overlap between user-supplied and device-owned flags */
CTASSERT((IEEE80211_KEY_COMMON & IEEE80211_KEY_DEVICE) == 0);

/*
 * Establish a relationship between the specified key and cipher
 * and, if necessary, allocate a hardware index from the driver.
 * Note that when a fixed key index is required it must be specified.
 *
 * This must be the first call applied to a key; all the other key
 * routines assume wk_cipher is setup.
 *
 * Locking must be handled by the caller using:
 *      ieee80211_key_update_begin(vap);
 *      ieee80211_key_update_end(vap);
 */
int
ieee80211_crypto_newkey(struct ieee80211vap *vap,
        int cipher, int flags, struct ieee80211_key *key)
{
        struct ieee80211com *ic = vap->iv_ic;
        const struct ieee80211_cipher *cip;
        ieee80211_keyix keyix, rxkeyix;
        void *keyctx;
        int oflags;

        IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
            "%s: cipher %u flags 0x%x keyix %u\n",
            __func__, cipher, flags, key->wk_keyix);

        /*
         * Validate cipher and set reference to cipher routines.
         */
        if (cipher >= IEEE80211_CIPHER_MAX) {
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
                    "%s: invalid cipher %u\n", __func__, cipher);
                vap->iv_stats.is_crypto_badcipher++;
                return 0;
        }
        cip = ciphers[cipher];
        if (cip == NULL) {
                /*
                 * Auto-load cipher module if we have a well-known name
                 * for it.  It might be better to use string names rather
                 * than numbers and craft a module name based on the cipher
                 * name; e.g. wlan_cipher_<cipher-name>.
                 */
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
                    "%s: unregistered cipher %u, load module %s\n",
                    __func__, cipher, cipher_modnames[cipher]);
                ieee80211_load_module(cipher_modnames[cipher]);
                /*
                 * If cipher module loaded it should immediately
                 * call ieee80211_crypto_register which will fill
                 * in the entry in the ciphers array.
                 */
                cip = ciphers[cipher];
                if (cip == NULL) {
                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
                            "%s: unable to load cipher %u, module %s\n",
                            __func__, cipher, cipher_modnames[cipher]);
                        vap->iv_stats.is_crypto_nocipher++;
                        return 0;
                }
        }

        oflags = key->wk_flags;
        flags &= IEEE80211_KEY_COMMON;
        /* NB: preserve device attributes */
        flags |= (oflags & IEEE80211_KEY_DEVICE);
        /*
         * If the hardware does not support the cipher then
         * fallback to a host-based implementation.
         */
        if ((ic->ic_cryptocaps & (1<<cipher)) == 0) {
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
                    "%s: no h/w support for cipher %s, falling back to s/w\n",
                    __func__, cip->ic_name);
                flags |= IEEE80211_KEY_SWCRYPT;
        }
        /*
         * Check if the software cipher is available; if not then
         * fail it early.
         *
         * Some devices do not support all ciphers in software
         * (for example they don't support a "raw" data path.)
         */
        if ((flags & IEEE80211_KEY_SWCRYPT) &&
            (ic->ic_sw_cryptocaps & (1<<cipher)) == 0) {
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
                    "%s: no s/w support for cipher %s, rejecting\n",
                    __func__, cip->ic_name);
                vap->iv_stats.is_crypto_swcipherfail++;
                return (0);
        }
        /*
         * Hardware TKIP with software MIC is an important
         * combination; we handle it by flagging each key,
         * the cipher modules honor it.
         */
        if (cipher == IEEE80211_CIPHER_TKIP &&
            (ic->ic_cryptocaps & IEEE80211_CRYPTO_TKIPMIC) == 0) {
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
                    "%s: no h/w support for TKIP MIC, falling back to s/w\n",
                    __func__);
                flags |= IEEE80211_KEY_SWMIC;
        }

        /*
         * Bind cipher to key instance.  Note we do this
         * after checking the device capabilities so the
         * cipher module can optimize space usage based on
         * whether or not it needs to do the cipher work.
         */
        if (key->wk_cipher != cip || key->wk_flags != flags) {
                /*
                 * Fillin the flags so cipher modules can see s/w
                 * crypto requirements and potentially allocate
                 * different state and/or attach different method
                 * pointers.
                 */
                key->wk_flags = flags;
                keyctx = cip->ic_attach(vap, key);
                if (keyctx == NULL) {
                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
                                "%s: unable to attach cipher %s\n",
                                __func__, cip->ic_name);
                        key->wk_flags = oflags; /* restore old flags */
                        vap->iv_stats.is_crypto_attachfail++;
                        return 0;
                }
                cipher_detach(key);
                key->wk_cipher = cip;           /* XXX refcnt? */
                key->wk_private = keyctx;
        }

        /*
         * Ask the driver for a key index if we don't have one.
         * Note that entries in the global key table always have
         * an index; this means it's safe to call this routine
         * for these entries just to setup the reference to the
         * cipher template.  Note also that when using software
         * crypto we also call the driver to give us a key index.
         */
        if ((key->wk_flags & IEEE80211_KEY_DEVKEY) == 0) {
                if (!dev_key_alloc(vap, key, &keyix, &rxkeyix)) {
                        /*
                         * Unable to setup driver state.
                         */
                        vap->iv_stats.is_crypto_keyfail++;
                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
                            "%s: unable to setup cipher %s\n",
                            __func__, cip->ic_name);
                        return 0;
                }
                if (key->wk_flags != flags) {
                        /*
                         * Driver overrode flags we setup; typically because
                         * resources were unavailable to handle _this_ key.
                         * Re-attach the cipher context to allow cipher
                         * modules to handle differing requirements.
                         */
                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
                            "%s: driver override for cipher %s, flags "
                            "%b -> %b\n", __func__, cip->ic_name,
                            oflags, IEEE80211_KEY_BITS,
                            key->wk_flags, IEEE80211_KEY_BITS);
                        keyctx = cip->ic_attach(vap, key);
                        if (keyctx == NULL) {
                                IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
                                    "%s: unable to attach cipher %s with "
                                    "flags %b\n", __func__, cip->ic_name,
                                    key->wk_flags, IEEE80211_KEY_BITS);
                                key->wk_flags = oflags; /* restore old flags */
                                vap->iv_stats.is_crypto_attachfail++;
                                return 0;
                        }
                        cipher_detach(key);
                        key->wk_cipher = cip;           /* XXX refcnt? */
                        key->wk_private = keyctx;
                }
                key->wk_keyix = keyix;
                key->wk_rxkeyix = rxkeyix;
                key->wk_flags |= IEEE80211_KEY_DEVKEY;
        }
        return 1;
}

/*
 * Remove the key (no locking, for internal use).
 */
static int
_ieee80211_crypto_delkey(struct ieee80211vap *vap, struct ieee80211_key *key)
{
        KASSERT(key->wk_cipher != NULL, ("No cipher!"));

        IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
            "%s: %s keyix %u flags %b rsc %ju tsc %ju len %u\n",
            __func__, key->wk_cipher->ic_name,
            key->wk_keyix, key->wk_flags, IEEE80211_KEY_BITS,
            key->wk_keyrsc[IEEE80211_NONQOS_TID], key->wk_keytsc,
            key->wk_keylen);

        if (key->wk_flags & IEEE80211_KEY_DEVKEY) {
                /*
                 * Remove hardware entry.
                 */
                /* XXX key cache */
                if (!dev_key_delete(vap, key)) {
                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
                            "%s: driver did not delete key index %u\n",
                            __func__, key->wk_keyix);
                        vap->iv_stats.is_crypto_delkey++;
                        /* XXX recovery? */
                }
        }
        cipher_detach(key);
        memset(key, 0, sizeof(*key));
        ieee80211_crypto_resetkey(vap, key, IEEE80211_KEYIX_NONE);
        return 1;
}

/*
 * Remove the specified key.
 */
int
ieee80211_crypto_delkey(struct ieee80211vap *vap, struct ieee80211_key *key)
{
        int status;

        ieee80211_key_update_begin(vap);
        status = _ieee80211_crypto_delkey(vap, key);
        ieee80211_key_update_end(vap);
        return status;
}

/*
 * Clear the global key table.
 */
void
ieee80211_crypto_delglobalkeys(struct ieee80211vap *vap)
{
        int i;

        ieee80211_key_update_begin(vap);
        for (i = 0; i < IEEE80211_WEP_NKID; i++)
                (void) _ieee80211_crypto_delkey(vap, &vap->iv_nw_keys[i]);
        ieee80211_key_update_end(vap);
}

/*
 * Set the contents of the specified key.
 *
 * Locking must be handled by the caller using:
 *      ieee80211_key_update_begin(vap);
 *      ieee80211_key_update_end(vap);
 */
int
ieee80211_crypto_setkey(struct ieee80211vap *vap, struct ieee80211_key *key)
{
        const struct ieee80211_cipher *cip = key->wk_cipher;

        KASSERT(cip != NULL, ("No cipher!"));

        IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
            "%s: %s keyix %u flags %b mac %s rsc %ju tsc %ju len %u\n",
            __func__, cip->ic_name, key->wk_keyix,
            key->wk_flags, IEEE80211_KEY_BITS, ether_sprintf(key->wk_macaddr),
            key->wk_keyrsc[IEEE80211_NONQOS_TID], key->wk_keytsc,
            key->wk_keylen);

        if ((key->wk_flags & IEEE80211_KEY_DEVKEY)  == 0) {
                /* XXX nothing allocated, should not happen */
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
                    "%s: no device key setup done; should not happen!\n",
                    __func__);
                vap->iv_stats.is_crypto_setkey_nokey++;
                return 0;
        }
        /*
         * Give cipher a chance to validate key contents.
         * XXX should happen before modifying state.
         */
        if (!cip->ic_setkey(key)) {
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
                    "%s: cipher %s rejected key index %u len %u flags %b\n",
                    __func__, cip->ic_name, key->wk_keyix,
                    key->wk_keylen, key->wk_flags, IEEE80211_KEY_BITS);
                vap->iv_stats.is_crypto_setkey_cipher++;
                return 0;
        }
        return dev_key_set(vap, key);
}

/**
 * @brief Return index if the key is a WEP key (0..3); -1 otherwise.
 *
 * This is different to "get_keyid" which defaults to returning
 * 0 for unicast keys; it assumes that it won't be used for WEP.
 *
 * @param vap the current VAP
 * @param k ieee80211_key to check
 * @returns 0..3 if it's a global/WEP key, -1 otherwise.
 */
int
ieee80211_crypto_get_key_wepidx(const struct ieee80211vap *vap,
    const struct ieee80211_key *k)
{

        if (ieee80211_is_key_global(vap, k)) {
                return (k - vap->iv_nw_keys);
        }
        return (-1);
}

/**
 * @brief Return the index of a unicast, global or IGTK key.
 *
 * Return the index of a key.  For unicast keys the index is 0..1.
 * For global/WEP keys it's 0..3.  For IGTK keys its 4..5.
 *
 * TODO: support >1 unicast key
 * TODO: support IGTK keys
 *
 * @param vap the current VAP
 * @param k ieee80211_key to check
 * @returns 0..3 for a WEP/global key, 0..1 for unicast key, 4..5 for IGTK key
 */
uint8_t
ieee80211_crypto_get_keyid(struct ieee80211vap *vap, struct ieee80211_key *k)
{
        if (ieee80211_is_key_global(vap, k)) {
                return (k - vap->iv_nw_keys);
        }

        return (0);
}

/**
 * @param Return the key to use for encrypting an mbuf frame to a node
 *
 * This routine chooses a suitable key used to encrypt the given frame with.
 * It doesn't do the encryption; it only chooses the key.  If a key is not
 * available then the routine will return NULL.
 *
 * It's up to the caller to enforce whether a key is absolutely required or not.
 *
 * @param ni The ieee80211_node to send the frame to
 * @param m the mbuf to encrypt
 * @returns the ieee80211_key to encrypt with, or NULL if there's no suitable key
 */
struct ieee80211_key *
ieee80211_crypto_get_txkey(struct ieee80211_node *ni, struct mbuf *m)
{
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211_frame *wh;

        /*
         * Multicast traffic always uses the multicast key.
         *
         * Historically we would fall back to the default
         * transmit key if there was no unicast key.  This
         * behaviour was documented up to IEEE Std 802.11-2016,
         * 12.9.2.2 Per-MSDU/Per-A-MSDU Tx pseudocode, in the
         * 'else' case but is no longer in later versions of
         * the standard.  Additionally falling back to the
         * group key for unicast was a security risk.
         */
        wh = mtod(m, struct ieee80211_frame *);
        if (IEEE80211_IS_MULTICAST(wh->i_addr1)) {
                if (vap->iv_def_txkey == IEEE80211_KEYIX_NONE) {
                        IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO,
                            wh->i_addr1,
                            "no default transmit key (%s) deftxkey %u",
                            __func__, vap->iv_def_txkey);
                        vap->iv_stats.is_tx_nodefkey++;
                        return NULL;
                }
                return &vap->iv_nw_keys[vap->iv_def_txkey];
        }

        if (IEEE80211_KEY_UNDEFINED(&ni->ni_ucastkey))
                return NULL;
        return &ni->ni_ucastkey;
}

/**
 * @brief Privacy encapsulate and encrypt the given mbuf.
 *
 * This routine handles the mechanics of encryption - expanding the
 * mbuf to add privacy headers, IV, ICV, MIC, MMIC, and then encrypts
 * the given mbuf if required.
 *
 * This should be called by the driver in its TX path as part of
 * encapsulation before passing frames to the hardware/firmware
 * queues.
 *
 * Drivers/hardware which does its own entirely offload path
 * should still call this for completeness - it indicates to the
 * driver that the frame itself should be encrypted.
 *
 * The driver should have set capability bits in the attach /
 * key allocation path to disable various encapsulation/encryption
 * features.
 *
 * @param ni ieee80211_node for this frame
 * @param mbuf mbuf to modify
 * @returns the key used if the frame is to be encrypted, NULL otherwise
 */
struct ieee80211_key *
ieee80211_crypto_encap(struct ieee80211_node *ni, struct mbuf *m)
{
        struct ieee80211_key *k;
        const struct ieee80211_cipher *cip;

        if ((k = ieee80211_crypto_get_txkey(ni, m)) != NULL) {
                cip = k->wk_cipher;
                return (cip->ic_encap(k, m) ? k : NULL);
        }

        return NULL;
}

/**
 * @brief Decapsulate and validate an encrypted frame.
 *
 * This handles an encrypted frame (one with the privacy bit set.)
 * It also obeys the key / config / receive packet flags for how
 * the driver says its already been processed.
 *
 * Unlike ieee80211_crypto_encap(), this isn't called in the driver.
 * Instead, drivers passed the potentially decrypted frame - fully,
 * partial, or not at all - and net80211 will call this as appropriate.
 *
 * This handles NICs (like ath(4)) which have a variable size between
 * the 802.11 header and 802.11 payload due to DMA alignment / encryption
 * engine concerns.
 *
 * If the frame was decrypted and validated successfully then 1 is returned
 * and the mbuf can be treated as an 802.11 frame.  If it is not decrypted
 * successfully or it was decrypted but failed validation/checks, then
 * 0 is returned.
 *
 * @param ni ieee80211_node for received frame
 * @param m mbuf frame to receive
 * @param hdrlen length of the 802.11 header, including trailing null bytes
 * @param key pointer to ieee80211_key that will be set if appropriate
 * @returns 0 if the frame wasn't decrypted/validated, 1 if decrypted/validated.
 */
int
ieee80211_crypto_decap(struct ieee80211_node *ni, struct mbuf *m, int hdrlen,
    struct ieee80211_key **key)
{
#define IEEE80211_WEP_HDRLEN    (IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN)
#define IEEE80211_WEP_MINLEN \
        (sizeof(struct ieee80211_frame) + \
        IEEE80211_WEP_HDRLEN + IEEE80211_WEP_CRCLEN)
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211_key *k;
        struct ieee80211_frame *wh;
        const struct ieee80211_rx_stats *rxs;
        const struct ieee80211_cipher *cip;
        uint8_t keyid;

        /*
         * Check for hardware decryption and IV stripping.
         * If the IV is stripped then we definitely can't find a key.
         * Set the key to NULL but return true; upper layers
         * will need to handle a NULL key for a successful
         * decrypt.
         */
        rxs = ieee80211_get_rx_params_ptr(m);
        if ((rxs != NULL) && (rxs->c_pktflags & IEEE80211_RX_F_DECRYPTED)) {
                if (rxs->c_pktflags & IEEE80211_RX_F_IV_STRIP) {
                        /*
                         * Hardware decrypted, IV stripped.
                         * We can't find a key with a stripped IV.
                         * Return successful.
                         */
                        *key = NULL;
                        return (1);
                }
        }

        /* NB: this minimum size data frame could be bigger */
        if (m->m_pkthdr.len < IEEE80211_WEP_MINLEN) {
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_ANY,
                        "%s: WEP data frame too short, len %u\n",
                        __func__, m->m_pkthdr.len);
                vap->iv_stats.is_rx_tooshort++; /* XXX need unique stat? */
                *key = NULL;
                return (0);
        }

        /*
         * Locate the key. If unicast and there is no unicast
         * key then we fall back to the key id in the header.
         * This assumes unicast keys are only configured when
         * the key id in the header is meaningless (typically 0).
         */
        wh = mtod(m, struct ieee80211_frame *);
        m_copydata(m, hdrlen + IEEE80211_WEP_IVLEN, sizeof(keyid), &keyid);
        if (IEEE80211_IS_MULTICAST(wh->i_addr1) ||
            IEEE80211_KEY_UNDEFINED(&ni->ni_ucastkey))
                k = &vap->iv_nw_keys[keyid >> 6];
        else
                k = &ni->ni_ucastkey;

        /*
         * Ensure crypto header is contiguous and long enough for all
         * decap work.
         */
        cip = k->wk_cipher;
        if (m->m_len < hdrlen + cip->ic_header) {
                IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO, wh->i_addr2,
                    "frame is too short (%d < %u) for crypto decap",
                    cip->ic_name, m->m_len, hdrlen + cip->ic_header);
                vap->iv_stats.is_rx_tooshort++;
                *key = NULL;
                return (0);
        }

        /*
         * Attempt decryption.
         *
         * If we fail then don't return the key - return NULL
         * and an error.
         */
        if (cip->ic_decap(k, m, hdrlen)) {
                /* success */
                *key = k;
                return (1);
        }

        /* Failure */
        *key = NULL;
        return (0);
#undef IEEE80211_WEP_MINLEN
#undef IEEE80211_WEP_HDRLEN
}

/**
 * @brief Check and remove any post-defragmentation MIC from an MSDU.
 *
 * This is called after defragmentation.  Crypto types that implement
 * a MIC/ICV check per MSDU will not implement this function.
 *
 * As an example, TKIP decapsulation covers both MIC/ICV checks per
 * MPDU (the "WEP" ICV) and then a Michael MIC verification on the
 * defragmented MSDU.  Please see 802.11-2020 12.5.2.1.3 (TKIP decapsulation)
 * for more information.
 *
 * @param vap   the current VAP
 * @param k     the current key
 * @param m     the mbuf representing the MSDU
 * @param f     set to 1 to force a MSDU MIC check, even if HW decrypted
 * @returns     0 if error / MIC check failed, 1 if OK
 */
int
ieee80211_crypto_demic(struct ieee80211vap *vap, struct ieee80211_key *k,
    struct mbuf *m, int force)
{
        const struct ieee80211_cipher *cip;
        const struct ieee80211_rx_stats *rxs;
        struct ieee80211_frame *wh;

        rxs = ieee80211_get_rx_params_ptr(m);
        wh = mtod(m, struct ieee80211_frame *);

        /*
         * Handle demic / mic errors from hardware-decrypted offload devices.
         */
        if ((rxs != NULL) && (rxs->c_pktflags & IEEE80211_RX_F_DECRYPTED)) {
                if ((rxs->c_pktflags & IEEE80211_RX_F_FAIL_MMIC) != 0) {
                        /*
                         * Hardware has said MMIC failed.  We don't care about
                         * whether it was stripped or not.
                         *
                         * Eventually - teach the demic methods in crypto
                         * modules to handle a NULL key and not to dereference
                         * it.
                         */
                        ieee80211_notify_michael_failure(vap, wh,
                            IEEE80211_KEYIX_NONE);
                        return (0);
                }

                if ((rxs->c_pktflags &
                    (IEEE80211_RX_F_MIC_STRIP|IEEE80211_RX_F_MMIC_STRIP)) != 0) {
                        /*
                         * Hardware has decrypted and not indicated a
                         * MIC failure and has stripped the MIC.
                         * We may not have a key, so for now just
                         * return OK.
                         */
                        return (1);
                }
        }

        /*
         * If we don't have a key at this point then we don't
         * have to demic anything.
         */
        if (k == NULL)
                return (1);

        cip = k->wk_cipher;
        return (cip->ic_miclen > 0 ? cip->ic_demic(k, m, force) : 1);
}

static void
load_ucastkey(void *arg, struct ieee80211_node *ni)
{
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211_key *k;

        if (vap->iv_state != IEEE80211_S_RUN)
                return;
        k = &ni->ni_ucastkey;
        if (k->wk_flags & IEEE80211_KEY_DEVKEY)
                dev_key_set(vap, k);
}

/*
 * Re-load all keys known to the 802.11 layer that may
 * have hardware state backing them.  This is used by
 * drivers on resume to push keys down into the device.
 */
void
ieee80211_crypto_reload_keys(struct ieee80211com *ic)
{
        struct ieee80211vap *vap;
        int i;

        /*
         * Keys in the global key table of each vap.
         */
        /* NB: used only during resume so don't lock for now */
        TAILQ_FOREACH(vap, &ic->ic_vaps, iv_next) {
                if (vap->iv_state != IEEE80211_S_RUN)
                        continue;
                for (i = 0; i < IEEE80211_WEP_NKID; i++) {
                        const struct ieee80211_key *k = &vap->iv_nw_keys[i];
                        if (k->wk_flags & IEEE80211_KEY_DEVKEY)
                                dev_key_set(vap, k);
                }
        }
        /*
         * Unicast keys.
         */
        ieee80211_iterate_nodes(&ic->ic_sta, load_ucastkey, NULL);
}

/*
 * Set the default key index for WEP, or KEYIX_NONE for no default TX key.
 *
 * This should be done as part of a key update block (iv_key_update_begin /
 * iv_key_update_end.)
 */
void
ieee80211_crypto_set_deftxkey(struct ieee80211vap *vap, ieee80211_keyix kid)
{

        /* XXX TODO: assert we're in a key update block */

        vap->iv_update_deftxkey(vap, kid);
}

/**
 * @brief Calculate the AAD required for this frame for AES-GCM/AES-CCM.
 *
 * The contents are described in 802.11-2020 12.5.3.3.3 (Construct AAD)
 * under AES-CCM and are shared with AES-GCM as covered in 12.5.5.3.3
 * (Construct AAD) (AES-GCM).
 *
 * NOTE: the first two bytes are a 16 bit big-endian length, which are used
 * by AES-CCM as part of the Adata field (RFC 3610, section 2.2
 * (Authentication)) to indicate the length of the Adata field itself.
 * Since this is small and fits in 0xfeff bytes, the length field
 * uses the two byte big endian option.
 *
 * AES-GCM doesn't require the length at the beginning and will need to
 * skip it.
 *
 * TODO: net80211 currently doesn't support negotiating SPP (Signaling
 * and Payload Protected A-MSDUs) and thus bit 7 of the QoS control field
 * is always masked.
 *
 * TODO: net80211 currently doesn't support DMG (802.11ad) so bit 7
 * (A-MSDU present) and bit 8 (A-MSDU type) are always masked.
 *
 * @param wh    802.11 frame to calculate the AAD over
 * @param aad   AAD (additional authentication data) buffer
 * @param len   The AAD buffer length in bytes.
 * @returns     The number of AAD payload bytes (ignoring the first two
 *              bytes, which are the AAD payload length in big-endian).
 */
uint16_t
ieee80211_crypto_init_aad(const struct ieee80211_frame *wh, uint8_t *aad,
    int len)
{
        uint16_t aad_len;

        memset(aad, 0, len);

        /*
         * AAD for PV0 MPDUs:
         *
         * 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)
         */
        aad[0] = 0;     /* AAD length >> 8 */
        /* NB: aad[1] set below */
        aad[2] = wh->i_fc[0] & 0x8f;    /* see above for bitfields */
        aad[3] = wh->i_fc[1] & 0xc7;    /* see above for bitfields */
        /* mask aad[3] b7 if frame is data frame w/ QoS control field */
        if (IEEE80211_IS_QOS_ANY(wh))
                aad[3] &= 0x7f;

        /* NB: we know 3 addresses are contiguous */
        memcpy(aad + 4, wh->i_addr1, 3 * IEEE80211_ADDR_LEN);
        aad[22] = wh->i_seq[0] & IEEE80211_SEQ_FRAG_MASK;
        aad[23] = 0; /* all bits masked */
        /*
         * Construct variable-length portion of AAD based
         * on whether this is a 4-address frame/QOS frame.
         * We always zero-pad to 32 bytes before running it
         * through the cipher.
         */
        if (IEEE80211_IS_DSTODS(wh)) {
                IEEE80211_ADDR_COPY(aad + 24,
                        ((const struct ieee80211_frame_addr4 *)wh)->i_addr4);
                if (IEEE80211_IS_QOS_ANY(wh)) {
                        const struct ieee80211_qosframe_addr4 *qwh4 =
                                (const struct ieee80211_qosframe_addr4 *) wh;
                        /* TODO: SPP A-MSDU / A-MSDU present bit */
                        aad[30] = qwh4->i_qos[0] & 0x0f;/* just priority bits */
                        aad[31] = 0;
                        aad_len = aad[1] = 22 + IEEE80211_ADDR_LEN + 2;
                } else {
                        *(uint16_t *)&aad[30] = 0;
                        aad_len = aad[1] = 22 + IEEE80211_ADDR_LEN;
                }
        } else {
                if (IEEE80211_IS_QOS_ANY(wh)) {
                        const struct ieee80211_qosframe *qwh =
                                (const struct ieee80211_qosframe*) wh;
                        /* TODO: SPP A-MSDU / A-MSDU present bit */
                        aad[24] = qwh->i_qos[0] & 0x0f; /* just priority bits */
                        aad[25] = 0;
                        aad_len = aad[1] = 22 + 2;
                } else {
                        *(uint16_t *)&aad[24] = 0;
                        aad_len = aad[1] = 22;
                }
                *(uint16_t *)&aad[26] = 0;
                *(uint32_t *)&aad[28] = 0;
        }

        return (aad_len);
}