/* $NetBSD: ieee80211_crypto.c,v 1.14 2006/11/16 01:33:40 christos Exp $ */ /*- * 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. */ #include #ifdef __FreeBSD__ __FBSDID("$FreeBSD: src/sys/net80211/ieee80211_crypto.c,v 1.12 2005/08/08 18:46:35 sam Exp $"); #endif #ifdef __NetBSD__ __KERNEL_RCSID(0, "$NetBSD: ieee80211_crypto.c,v 1.14 2006/11/16 01:33:40 christos Exp $"); #endif #include "opt_inet.h" /* * IEEE 802.11 generic crypto support. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Table of registered cipher modules. */ static const struct ieee80211_cipher *ciphers[IEEE80211_CIPHER_MAX]; #ifdef INET #include #include #endif #include /* XXX unneeded? */ static int _ieee80211_crypto_delkey(struct ieee80211com *, struct ieee80211_key *); /* * Default "null" key management routines. */ static int null_key_alloc(struct ieee80211com *ic, const struct ieee80211_key *k, ieee80211_keyix *keyix, ieee80211_keyix *rxkeyix) { if (!(&ic->ic_nw_keys[0] <= k && k < &ic->ic_nw_keys[IEEE80211_WEP_NKID])) { /* * 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 = k - ic->ic_nw_keys; } *rxkeyix = IEEE80211_KEYIX_NONE; /* XXX maybe *keyix? */ return 1; } static int null_key_delete(struct ieee80211com *ic, const struct ieee80211_key *k) { return 1; } static int null_key_set(struct ieee80211com *ic, const struct ieee80211_key *k, const u_int8_t mac[IEEE80211_ADDR_LEN]) { return 1; } static void null_key_update(struct ieee80211com *ic) {} /* * 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 ieee80211com *ic, struct ieee80211_key *key) { return key->wk_cipher->ic_attach(ic, key); } /* * Wrappers for driver key management methods. */ static __inline int dev_key_alloc(struct ieee80211com *ic, const struct ieee80211_key *key, ieee80211_keyix *keyix, ieee80211_keyix *rxkeyix) { return ic->ic_crypto.cs_key_alloc(ic, key, keyix, rxkeyix); } static __inline int dev_key_delete(struct ieee80211com *ic, const struct ieee80211_key *key) { return ic->ic_crypto.cs_key_delete(ic, key); } static __inline int dev_key_set(struct ieee80211com *ic, const struct ieee80211_key *key, const u_int8_t mac[IEEE80211_ADDR_LEN]) { return ic->ic_crypto.cs_key_set(ic, key, mac); } /* * Setup crypto support. */ void ieee80211_crypto_attach(struct ieee80211com *ic) { struct ieee80211_crypto_state *cs = &ic->ic_crypto; int i; /* NB: we assume everything is pre-zero'd */ cs->cs_def_txkey = IEEE80211_KEYIX_NONE; cs->cs_max_keyix = IEEE80211_WEP_NKID; ciphers[IEEE80211_CIPHER_NONE] = &ieee80211_cipher_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 = null_key_alloc; cs->cs_key_set = null_key_set; cs->cs_key_delete = null_key_delete; cs->cs_key_update_begin = null_key_update; cs->cs_key_update_end = null_key_update; } /* * Teardown crypto support. */ void ieee80211_crypto_detach(struct ieee80211com *ic) { ieee80211_crypto_delglobalkeys(ic); } /* * Register a crypto cipher module. */ void ieee80211_crypto_register(const struct ieee80211_cipher *cip) { if (cip->ic_cipher >= IEEE80211_CIPHER_MAX) { 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) { 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) { 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) { 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[] = { "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 */ }; /* * 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 (XXX). * * 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(struct ieee80211com *ic, int cipher, int flags, struct ieee80211_key *key) { #define N(a) (sizeof(a) / sizeof(a[0])) const struct ieee80211_cipher *cip; ieee80211_keyix keyix, rxkeyix; void *keyctx; int oflags; /* * Validate cipher and set reference to cipher routines. */ if (cipher >= IEEE80211_CIPHER_MAX) { IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, "%s: invalid cipher %u\n", __func__, cipher); ic->ic_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_. */ if (cipher < N(cipher_modnames)) { IEEE80211_DPRINTF(ic, 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(ic, IEEE80211_MSG_CRYPTO, "%s: unable to load cipher %u, module %s\n", __func__, cipher, cipher < N(cipher_modnames) ? cipher_modnames[cipher] : ""); ic->ic_stats.is_crypto_nocipher++; 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<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_DPRINTF(ic, 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) { again: /* * Fillin the flags so cipher modules can see s/w * crypto requirements and potentially allocate * different state and/or attach different method * pointers. * * XXX this is not right when s/w crypto fallback * fails and we try to restore previous state. */ key->wk_flags = flags; keyctx = cip->ic_attach(ic, key); if (keyctx == NULL) { IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, "%s: unable to attach cipher %s\n", __func__, cip->ic_name); key->wk_flags = oflags; /* restore old flags */ ic->ic_stats.is_crypto_attachfail++; return 0; } cipher_detach(key); key->wk_cipher = cip; /* XXX refcnt? */ key->wk_private = keyctx; } /* * Commit to requested usage so driver can see the flags. */ key->wk_flags = 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) { ic->ic_stats.is_crypto_swfallback++; IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, "%s: no h/w resources for cipher %s, " "falling back to s/w\n", __func__, cip->ic_name); oflags = key->wk_flags; flags |= IEEE80211_KEY_SWCRYPT; if (cipher == IEEE80211_CIPHER_TKIP) flags |= IEEE80211_KEY_SWMIC; goto again; } ic->ic_stats.is_crypto_keyfail++; IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, "%s: unable to setup cipher %s\n", __func__, cip->ic_name); return 0; } key->wk_keyix = keyix; key->wk_rxkeyix = rxkeyix; } return 1; #undef N } /* * Remove the key (no locking, for internal use). */ static int _ieee80211_crypto_delkey(struct ieee80211com *ic, struct ieee80211_key *key) { ieee80211_keyix keyix; IASSERT(key->wk_cipher != NULL, ("No cipher!")); IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, "%s: %s keyix %u flags 0x%x rsc %ju tsc %ju len %u\n", __func__, key->wk_cipher->ic_name, key->wk_keyix, key->wk_flags, key->wk_keyrsc, key->wk_keytsc, key->wk_keylen); keyix = key->wk_keyix; if (keyix != IEEE80211_KEYIX_NONE) { /* * Remove hardware entry. */ /* XXX key cache */ if (!dev_key_delete(ic, key)) { IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, "%s: driver did not delete key index %u\n", __func__, keyix); ic->ic_stats.is_crypto_delkey++; /* XXX recovery? */ } } cipher_detach(key); memset(key, 0, sizeof(*key)); ieee80211_crypto_resetkey(ic, key, IEEE80211_KEYIX_NONE); return 1; } /* * Remove the specified key. */ int ieee80211_crypto_delkey(struct ieee80211com *ic, struct ieee80211_key *key) { int status; ieee80211_key_update_begin(ic); status = _ieee80211_crypto_delkey(ic, key); ieee80211_key_update_end(ic); return status; } /* * Clear the global key table. */ void ieee80211_crypto_delglobalkeys(struct ieee80211com *ic) { int i; ieee80211_key_update_begin(ic); for (i = 0; i < IEEE80211_WEP_NKID; i++) (void) _ieee80211_crypto_delkey(ic, &ic->ic_nw_keys[i]); ieee80211_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(struct ieee80211com *ic, struct ieee80211_key *key, const u_int8_t macaddr[IEEE80211_ADDR_LEN]) { const struct ieee80211_cipher *cip = key->wk_cipher; IASSERT(cip != NULL, ("No cipher!")); IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, "%s: %s keyix %u flags 0x%x mac %s rsc %ju tsc %ju len %u\n", __func__, cip->ic_name, key->wk_keyix, key->wk_flags, ether_sprintf(macaddr), key->wk_keyrsc, key->wk_keytsc, key->wk_keylen); /* * Give cipher a chance to validate key contents. * XXX should happen before modifying state. */ if (!cip->ic_setkey(key)) { IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, "%s: cipher %s rejected key index %u len %u flags 0x%x\n", __func__, cip->ic_name, key->wk_keyix, key->wk_keylen, key->wk_flags); ic->ic_stats.is_crypto_setkey_cipher++; return 0; } if (key->wk_keyix == IEEE80211_KEYIX_NONE) { /* XXX nothing allocated, should not happen */ IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, "%s: no key index; should not happen!\n", __func__); ic->ic_stats.is_crypto_setkey_nokey++; return 0; } return dev_key_set(ic, key, macaddr); } /* * Add privacy headers appropriate for the specified key. */ struct ieee80211_key * ieee80211_crypto_encap(struct ieee80211com *ic, struct ieee80211_node *ni, struct mbuf *m) { struct ieee80211_key *k; struct ieee80211_frame *wh; const struct ieee80211_cipher *cip; u_int8_t keyid; /* * Multicast traffic always uses the multicast key. * Otherwise if a unicast key is set we use that and * it is always key index 0. When no unicast key is * set we fall back to the default transmit key. */ wh = mtod(m, struct ieee80211_frame *); if (IEEE80211_IS_MULTICAST(wh->i_addr1) || ni->ni_ucastkey.wk_cipher == &ieee80211_cipher_none) { if (ic->ic_def_txkey == IEEE80211_KEYIX_NONE) { IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, "[%s] no default transmit key (%s) deftxkey %u\n", ether_sprintf(wh->i_addr1), __func__, ic->ic_def_txkey); ic->ic_stats.is_tx_nodefkey++; return NULL; } keyid = ic->ic_def_txkey; k = &ic->ic_nw_keys[ic->ic_def_txkey]; } else { keyid = 0; k = &ni->ni_ucastkey; } cip = k->wk_cipher; return (cip->ic_encap(k, m, keyid<<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(struct ieee80211com *ic, struct ieee80211_node *ni, struct mbuf *m, int hdrlen) { #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 ieee80211_key *k; struct ieee80211_frame *wh; const struct ieee80211_cipher *cip; u_int8_t keyid; /* NB: this minimum size data frame could be bigger */ if (m->m_pkthdr.len < IEEE80211_WEP_MINLEN) { IEEE80211_DPRINTF(ic, IEEE80211_MSG_ANY, "%s: WEP data frame too short, len %u\n", __func__, m->m_pkthdr.len); ic->ic_stats.is_rx_tooshort++; /* XXX need unique stat? */ 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). */ wh = mtod(m, struct ieee80211_frame *); m_copydata(m, hdrlen + IEEE80211_WEP_IVLEN, sizeof(keyid), &keyid); if (IEEE80211_IS_MULTICAST(wh->i_addr1) || ni->ni_ucastkey.wk_cipher == &ieee80211_cipher_none) k = &ic->ic_nw_keys[keyid >> 6]; else k = &ni->ni_ucastkey; /* * Insure crypto header is contiguous for all decap work. */ cip = k->wk_cipher; if (m->m_len < hdrlen + cip->ic_header && (m = m_pullup(m, hdrlen + cip->ic_header)) == NULL) { IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO, "[%s] unable to pullup %s header\n", ether_sprintf(wh->i_addr2), cip->ic_name); ic->ic_stats.is_rx_wepfail++; /* XXX */ return NULL; } return (cip->ic_decap(k, m, hdrlen) ? k : NULL); #undef IEEE80211_WEP_MINLEN #undef IEEE80211_WEP_HDRLEN }