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NetBSD/sys/net80211/ieee80211_crypto.c

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/* $NetBSD: ieee80211_crypto.c,v 1.23 2018/05/08 07:02:07 maxv 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 <sys/cdefs.h>
#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 1.23 2018/05/08 07:02:07 maxv Exp $");
#endif
#ifdef _KERNEL_OPT
#include "opt_inet.h"
#endif
/*
* IEEE 802.11 generic crypto support.
*/
#include <sys/param.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/endian.h>
#include <sys/errno.h>
#include <sys/proc.h>
#include <sys/sysctl.h>
#include <net/if.h>
#include <net/if_media.h>
#include <net/if_arp.h>
#include <net/if_ether.h>
#include <net/if_llc.h>
#include <net80211/ieee80211_netbsd.h>
#include <net80211/ieee80211_var.h>
/*
* Table of registered cipher modules.
*/
static const struct ieee80211_cipher *ciphers[IEEE80211_CIPHER_MAX];
#ifdef INET
#include <netinet/in.h>
#include <net/if_ether.h>
#endif
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);
}
/*
* 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_<cipher-name>.
*/
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] : "<unknown>");
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
* fall back to a host-based implementation.
*/
if ((ic->ic_caps & (1<<cipher)) == 0) {
IEEE80211_DPRINTF(ic, 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;
}
/*
* 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.
*
* XXX XXX XXX: Here we modify 'm', and potentially reallocate it. We
* should pass back to the caller the updated pointer to avoid
* use-after-frees. This can be done by changing the argument to be **m,
* but many drivers will have to be changed accordingly.
*/
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, *hdr;
int hdrlen;
/*
* 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;
/*
* The crypto header is added after the IEEE802.11 header. Prepend
* the size of the crypto header, and move the IEEE802.11 header back
* to the beginning of the mbuf. Ensure everything is contiguous.
*/
hdrlen = ieee80211_hdrspace(ic, mtod(m, void *));
M_PREPEND(m, cip->ic_header, M_NOWAIT);
if (m && m->m_len < hdrlen + cip->ic_header) {
m = m_pullup(m, hdrlen + cip->ic_header);
}
if (m == NULL) {
return NULL;
}
hdr = mtod(m, u_int8_t *);
memmove(hdr, hdr + cip->ic_header, hdrlen);
return (cip->ic_encap(k, m, keyid<<6) ? k : NULL);
}
#define IEEE80211_WEP_HDRLEN (IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN)
#define IEEE80211_WEP_MINLEN \
(sizeof(struct ieee80211_frame) + \
IEEE80211_WEP_HDRLEN + IEEE80211_WEP_CRCLEN)
/*
* 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 **mp, int hdrlen)
{
const struct ieee80211_cipher *cip;
struct ieee80211_key *k;
struct ieee80211_frame *wh;
struct mbuf *m = *mp;
u_int8_t keyid;
KASSERT((m->m_flags & M_PKTHDR) != 0);
/*
* This minimum size data frame could be bigger. It is re-checked
* below.
*/
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++;
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);
*mp = m;
}
if (m == NULL) {
ic->ic_stats.is_rx_tooshort++;
return NULL;
}
/*
* Ensure there is a header+trailer included.
*/
if (m->m_pkthdr.len < hdrlen + cip->ic_header + cip->ic_trailer) {
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++;
return NULL;
}
return (cip->ic_decap(k, m, hdrlen) ? k : NULL);
}
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