io/net80211/net80211_crypto.c

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Copyright (c) 2001 Atsushi Onoe
 * Copyright (c) 2002-2005 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.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * 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.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

/*
 * IEEE 802.11 generic crypto support
 */
#include <sys/types.h>
#include <sys/note.h>
#include <sys/crypto/common.h>
#include <sys/crypto/api.h>
#include <sys/strsun.h>
#include "net80211_impl.h"

extern const struct ieee80211_cipher wep;
extern const struct ieee80211_cipher tkip;
extern const struct ieee80211_cipher ccmp;

/*
 * Table of registered cipher modules.
 */
static const char *cipher_modnames[] = {
    "wlan_wep", /* IEEE80211_CIPHER_WEP */
    "wlan_tkip",    /* IEEE80211_CIPHER_TKIP */
    "wlan_aes_ocb", /* IEEE80211_CIPHER_AES_OCB */
    "wlan_ccmp",    /* IEEE80211_CIPHER_AES_CCM */
    "wlan_ckip",    /* IEEE80211_CIPHER_CKIP */
};

/*
 * Default "null" key management routines.
 */
/* ARGSUSED */
static int
nulldev_key_alloc(ieee80211com_t *ic, const struct ieee80211_key *k,
    ieee80211_keyix *keyix, ieee80211_keyix *rxkeyix)
{
    *keyix = 0; /* use key index 0 for ucast key */
    *rxkeyix = IEEE80211_KEYIX_NONE;
    return (1);
}

/* ARGSUSED */
static int
nulldev_key_delete(ieee80211com_t *ic, const struct ieee80211_key *k)
{
    return (1);
}

/* ARGSUSED */
static int
nulldev_key_set(ieee80211com_t *ic, const struct ieee80211_key *k,
    const uint8_t *mac)
{
    return (1);
}

/* ARGSUSED */
static void
nulldev_key_update(ieee80211com_t *ic)
{
    /* noop */
}

/*
 * Reset key state to an unused state.  The crypto
 * key allocation mechanism insures other state (e.g.
 * key data) is properly setup before a key is used.
 */
void
ieee80211_crypto_resetkey(ieee80211com_t *ic,
    struct ieee80211_key *k, ieee80211_keyix ix)
{
    k->wk_cipher = &ieee80211_cipher_none;
    k->wk_private = k->wk_cipher->ic_attach(ic, k);
    k->wk_keyix = ix;
    k->wk_flags = IEEE80211_KEY_XMIT | IEEE80211_KEY_RECV;
}

/*
 * 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
 * and we blindly assign it w/o consulting the driver.
 *
 * 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(ic);
 *  ieee80211_key_update_end(ic);
 */
int
ieee80211_crypto_newkey(ieee80211com_t *ic, int cipher, int flags,
    struct ieee80211_key *key)
{
    const struct ieee80211_cipher *cip;
    ieee80211_keyix keyix, rxkeyix;
    void *keyctx;
    uint16_t oflags;

    /*
     * Validate cipher and set reference to cipher routines.
     */
    if (cipher >= IEEE80211_CIPHER_MAX) {
        ieee80211_dbg(IEEE80211_MSG_CRYPTO, "ieee80211_crypto_newkey: "
            "invalid cipher %u\n", cipher);
        return (0);
    }
    cip = ic->ic_ciphers[cipher];
    /* already load all the ciphers, cip can't be NULL */
    if (cip == NULL) {
        ieee80211_dbg(IEEE80211_MSG_CRYPTO, "ieee80211_crypto_newkey: "
            "unable to load cipher %u, module %s\n",
            cipher, cipher < IEEE80211_N(cipher_modnames) ?
            cipher_modnames[cipher] : "<unknown>");
        return (0);
    }

    oflags = key->wk_flags;
    flags &= IEEE80211_KEY_COMMON;
    /*
     * If the hardware does not support the cipher then
     * fallback to a host-based implementation.
     */
    if ((ic->ic_caps & (1<<cipher)) == 0) {
        ieee80211_dbg(IEEE80211_MSG_CRYPTO, "ieee80211_crypto_newkey: "
            "no h/w support for cipher %s, falling back to s/w\n",
            cip->ic_name);
        flags |= IEEE80211_KEY_SWCRYPT;
    }
    /*
     * 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_caps & IEEE80211_C_TKIPMIC) == 0) {
        ieee80211_dbg(IEEE80211_MSG_CRYPTO,
            "no h/w support for TKIP MIC, falling back to s/w\n");
        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) {
again:
        /*
         * 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 = (uint16_t)flags;
        keyctx = cip->ic_attach(ic, key);
        if (keyctx == NULL) {
            ieee80211_dbg(IEEE80211_MSG_CRYPTO, "crypto_setkey: "
                "unable to attach cipher %s\n", cip->ic_name);
            key->wk_flags = oflags; /* restore old flags */
            return (0);
        }
        CIPHER_DETACH(key);     /* Detach old cipher */
        key->wk_cipher = cip;
        key->wk_private = keyctx;
    }
    /*
     * Commit to requested usage so driver can see the flags.
     */
    key->wk_flags = (uint16_t)flags;

    /*
     * 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_keyix == IEEE80211_KEYIX_NONE) {
        if (!DEV_KEY_ALLOC(ic, key, &keyix, &rxkeyix)) {
            /*
             * Driver has no room; fallback to doing crypto
             * in the host.  We change the flags and start the
             * procedure over.  If we get back here then there's
             * no hope and we bail.  Note that this can leave
             * the key in a inconsistent state if the caller
             * continues to use it.
             */
            if ((key->wk_flags & IEEE80211_KEY_SWCRYPT) == 0) {
                ieee80211_dbg(IEEE80211_MSG_CRYPTO,
                    "crypto_setkey: "
                    "no h/w resources for cipher %s, "
                    "falling back to s/w\n", cip->ic_name);
                oflags = key->wk_flags;
                flags |= IEEE80211_KEY_SWCRYPT;
                if (cipher == IEEE80211_CIPHER_TKIP)
                    flags |= IEEE80211_KEY_SWMIC;
                goto again;
            }
            ieee80211_dbg(IEEE80211_MSG_CRYPTO, "crypto_setkey: "
                "unable to setup cipher %s\n", cip->ic_name);
            return (0);
        }
        key->wk_keyix = keyix;
        key->wk_rxkeyix = rxkeyix;
    }
    return (1);
}

/*
 * Remove the key (no locking, for internal use).
 */
static int
ieee80211_crypto_delkey_locked(ieee80211com_t *ic, struct ieee80211_key *key)
{
    uint16_t keyix;

    ASSERT(key->wk_cipher != NULL);

    keyix = key->wk_keyix;
    if (keyix != IEEE80211_KEYIX_NONE) {
        /*
         * Remove hardware entry.
         */
        if (!DEV_KEY_DELETE(ic, key)) {
            ieee80211_dbg(IEEE80211_MSG_CRYPTO,
                "ieee80211_crypto_delkey_locked: ",
                "driverdeletes key %u failed\n", keyix);
        }
    }
    CIPHER_DETACH(key);
    bzero(key, sizeof (struct ieee80211_key));
    /* NB: cannot depend on key index to decide this */
    ieee80211_crypto_resetkey(ic, key, IEEE80211_KEYIX_NONE);
    return (1);
}

/*
 * Remove the specified key.
 */
int
ieee80211_crypto_delkey(ieee80211com_t *ic, struct ieee80211_key *key)
{
    int status;

    KEY_UPDATE_BEGIN(ic);
    status = ieee80211_crypto_delkey_locked(ic, key);
    KEY_UPDATE_END(ic);
    return (status);
}

/*
 * Clear the global key table.
 */
static void
ieee80211_crypto_delglobalkeys(ieee80211com_t *ic)
{
    int i;

    KEY_UPDATE_BEGIN(ic);
    for (i = 0; i < IEEE80211_WEP_NKID; i++)
        (void) ieee80211_crypto_delkey_locked(ic, &ic->ic_nw_keys[i]);
    KEY_UPDATE_END(ic);
}

/*
 * Set the contents of the specified key.
 *
 * Locking must be handled by the caller using:
 *  ieee80211_key_update_begin(ic);
 *  ieee80211_key_update_end(ic);
 */
int
ieee80211_crypto_setkey(ieee80211com_t *ic, struct ieee80211_key *key,
    const uint8_t *macaddr)
{
    const struct ieee80211_cipher *cip = key->wk_cipher;

    ASSERT(cip != NULL);

    ieee80211_dbg(IEEE80211_MSG_CRYPTO, "ieee80211_crypto_setkey: "
        "%s keyix %u flags 0x%x mac %s len %u\n",
        cip->ic_name, key->wk_keyix, key->wk_flags,
        ieee80211_macaddr_sprintf(macaddr), key->wk_keylen);

    /*
     * Give cipher a chance to validate key contents.
     * should happen before modifying state.
     */
    if (cip->ic_setkey(key) == 0) {
        ieee80211_dbg(IEEE80211_MSG_CRYPTO, "ieee80211_crypto_setkey: "
            "cipher %s rejected key index %u len %u flags 0x%x\n",
            cip->ic_name, key->wk_keyix, key->wk_keylen,
            key->wk_flags);
        return (0);
    }
    if (key->wk_keyix == IEEE80211_KEYIX_NONE) {
        ieee80211_dbg(IEEE80211_MSG_CRYPTO, "ieee80211_crypto_setkey: "
            "no key index; should not happen!\n");
        return (0);
    }
    return (DEV_KEY_SET(ic, key, macaddr));
}

/*
 * Return the transmit key to use in sending a frame.
 */
struct ieee80211_key *
ieee80211_crypto_getkey(ieee80211com_t *ic)
{
    if (ic->ic_def_txkey == IEEE80211_KEYIX_NONE ||
        KEY_UNDEFINED(ic->ic_nw_keys[ic->ic_def_txkey]))
        return (NULL);
    return (&ic->ic_nw_keys[ic->ic_def_txkey]);
}

uint8_t
ieee80211_crypto_getciphertype(ieee80211com_t *ic)
{
    struct ieee80211_key *key;
    uint32_t cipher;
    static const uint8_t ciphermap[] = {
        WIFI_SEC_WEP,   /* IEEE80211_CIPHER_WEP */
        WIFI_SEC_WPA,   /* IEEE80211_CIPHER_TKIP */
        (uint8_t)-1,    /* IEEE80211_CIPHER_AES_OCB */
        WIFI_SEC_WPA,   /* IEEE80211_CIPHER_AES_CCM */
        (uint8_t)-1,    /* IEEE80211_CIPHER_CKIP */
        WIFI_SEC_NONE,  /* IEEE80211_CIPHER_NONE */
    };

    if ((ic->ic_flags & IEEE80211_F_PRIVACY) == 0)
        return (WIFI_SEC_NONE);

    key = ieee80211_crypto_getkey(ic);
    if (key == NULL)
        return (WIFI_SEC_NONE);

    cipher = key->wk_cipher->ic_cipher;
    ASSERT(cipher < IEEE80211_N(ciphermap));
    return (ciphermap[cipher]);
}

/*
 * Add privacy headers appropriate for the specified key.
 */
struct ieee80211_key *
ieee80211_crypto_encap(ieee80211com_t *ic, mblk_t *mp)
{
    struct ieee80211_key *k;
    const struct ieee80211_cipher *cip;
    uint8_t keyix;

    if (ic->ic_def_txkey == IEEE80211_KEYIX_NONE) {
        ieee80211_dbg(IEEE80211_MSG_CRYPTO,
            "ieee80211_crypto_encap: %s",
            " No default xmit key for frame\n");
        return (NULL);
    }
    keyix = ic->ic_def_txkey;
    k = &ic->ic_nw_keys[ic->ic_def_txkey];
    cip = k->wk_cipher;
    return (cip->ic_encap(k, mp, keyix<<6) ? k : NULL);
}

/*
 * Validate and strip privacy headers (and trailer) for a
 * received frame that has the WEP/Privacy bit set.
 */
struct ieee80211_key *
ieee80211_crypto_decap(ieee80211com_t *ic, mblk_t *mp, int hdrlen)
{
    struct ieee80211_key *k;
    const struct ieee80211_cipher *cip;
    uint8_t *ivp;
    uint8_t keyid;

    /* NB: this minimum size data frame could be bigger */
    if (MBLKL(mp) < IEEE80211_WEP_MINLEN) {
        ieee80211_dbg(IEEE80211_MSG_CRYPTO, "ieee80211_crypto_decap:"
            " WEP data frame too short, len %u\n",
            MBLKL(mp));
        return (NULL);
    }
    /*
     * 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).
     */
    ivp = mp->b_rptr + hdrlen;
    keyid = ivp[IEEE80211_WEP_IVLEN];
    k = &ic->ic_nw_keys[keyid >> 6];

    /* check to avoid panic when wep is on but key is not set */
    if (k->wk_cipher == &ieee80211_cipher_none ||
        k->wk_cipher == NULL)
        return (NULL);

    cip = k->wk_cipher;
    return ((cip->ic_decap)(k, mp, hdrlen) ? k : NULL);
}

/*
 * Setup crypto support.
 */
void
ieee80211_crypto_attach(ieee80211com_t *ic)
{
    struct ieee80211_crypto_state *cs = &ic->ic_crypto;
    int i;

    (void) crypto_mech2id(SUN_CKM_RC4); /* Load RC4 */
    (void) crypto_mech2id(SUN_CKM_AES_CBC); /* Load AES-CBC */
    (void) crypto_mech2id(SUN_CKM_AES_CCM); /* Load AES-CCM */

    /* NB: we assume everything is pre-zero'd */
    cs->cs_def_txkey = IEEE80211_KEYIX_NONE;
    for (i = 0; i < IEEE80211_WEP_NKID; i++) {
        ieee80211_crypto_resetkey(ic, &cs->cs_nw_keys[i],
            IEEE80211_KEYIX_NONE);
    }

    /*
     * Initialize the driver key support routines to noop entries.
     * This is useful especially for the cipher test modules.
     */
    cs->cs_key_alloc = nulldev_key_alloc;
    cs->cs_key_set = nulldev_key_set;
    cs->cs_key_delete = nulldev_key_delete;
    cs->cs_key_update_begin = nulldev_key_update;
    cs->cs_key_update_end = nulldev_key_update;

    ieee80211_crypto_register(ic, &wep);
    ieee80211_crypto_register(ic, &tkip);
    ieee80211_crypto_register(ic, &ccmp);
}

/*
 * Teardown crypto support.
 */
void
ieee80211_crypto_detach(ieee80211com_t *ic)
{
    ieee80211_crypto_delglobalkeys(ic);

    ieee80211_crypto_unregister(ic, &wep);
    ieee80211_crypto_unregister(ic, &tkip);
    ieee80211_crypto_unregister(ic, &ccmp);
}

/*
 * Register a crypto cipher module.
 */
void
ieee80211_crypto_register(ieee80211com_t *ic,
    const struct ieee80211_cipher *cip)
{
    if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) {
        ieee80211_err("ieee80211_crypto_register: "
            "cipher %s has an invalid cipher index %u\n",
            cip->ic_name, cip->ic_cipher);
        return;
    }
    if (ic->ic_ciphers[cip->ic_cipher] != NULL &&
        ic->ic_ciphers[cip->ic_cipher] != cip) {
        ieee80211_err("ieee80211_crypto_register: "
            "cipher %s registered with a different template\n",
            cip->ic_name);
        return;
    }
    ic->ic_ciphers[cip->ic_cipher] = cip;
}

/*
 * Unregister a crypto cipher module.
 */
void
ieee80211_crypto_unregister(ieee80211com_t *ic,
    const struct ieee80211_cipher *cip)
{
    if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) {
        ieee80211_err("ieee80211_crypto_unregister: "
            "cipher %s has an invalid cipher index %u\n",
            cip->ic_name, cip->ic_cipher);
        return;
    }
    if (ic->ic_ciphers[cip->ic_cipher] != NULL &&
        ic->ic_ciphers[cip->ic_cipher] != cip) {
        ieee80211_err("ieee80211_crypto_unregister: "
            "cipher %s registered with a different template\n",
            cip->ic_name);
        return;
    }
    /* NB: don't complain about not being registered */
    ic->ic_ciphers[cip->ic_cipher] = NULL;
}