OpenBSD-4.6/sys/net80211/ieee80211_crypto_ccmp.c
/* $OpenBSD: ieee80211_crypto_ccmp.c,v 1.8 2008/12/03 17:25:41 damien Exp $ */
/*-
* Copyright (c) 2008 Damien Bergamini <damien.bergamini@free.fr>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* This code implements the CTR with CBC-MAC protocol (CCMP) defined in
* IEEE Std 802.11-2007 section 8.3.3.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <sys/socket.h>
#include <sys/endian.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_media.h>
#include <net/if_arp.h>
#include <net/if_llc.h>
#ifdef INET
#include <netinet/in.h>
#include <netinet/if_ether.h>
#endif
#include <net80211/ieee80211_var.h>
#include <net80211/ieee80211_crypto.h>
#include <crypto/rijndael.h>
/* CCMP software crypto context */
struct ieee80211_ccmp_ctx {
rijndael_ctx rijndael;
};
/*
* Initialize software crypto context. This function can be overridden
* by drivers doing hardware crypto.
*/
int
ieee80211_ccmp_set_key(struct ieee80211com *ic, struct ieee80211_key *k)
{
struct ieee80211_ccmp_ctx *ctx;
ctx = malloc(sizeof(*ctx), M_DEVBUF, M_NOWAIT | M_ZERO);
if (ctx == NULL)
return ENOMEM;
rijndael_set_key_enc_only(&ctx->rijndael, k->k_key, 128);
k->k_priv = ctx;
return 0;
}
void
ieee80211_ccmp_delete_key(struct ieee80211com *ic, struct ieee80211_key *k)
{
if (k->k_priv != NULL)
free(k->k_priv, M_DEVBUF);
k->k_priv = NULL;
}
/*-
* Counter with CBC-MAC (CCM) - see RFC3610.
* CCMP uses the following CCM parameters: M = 8, L = 2
*/
static void
ieee80211_ccmp_phase1(rijndael_ctx *ctx, const struct ieee80211_frame *wh,
u_int64_t pn, int lm, u_int8_t b[16], u_int8_t a[16], u_int8_t s0[16])
{
u_int8_t auth[32], nonce[13];
u_int8_t *aad;
u_int8_t tid = 0;
int la, i;
/* construct AAD (additional authenticated data) */
aad = &auth[2]; /* skip l(a), will be filled later */
*aad = wh->i_fc[0];
/* 11w: conditionnally mask subtype field */
if ((wh->i_fc[0] & IEEE80211_FC0_TYPE_MASK) ==
IEEE80211_FC0_TYPE_DATA)
*aad &= ~IEEE80211_FC0_SUBTYPE_MASK;
aad++;
/* protected bit is already set in wh */
*aad = wh->i_fc[1];
*aad &= ~(IEEE80211_FC1_RETRY | IEEE80211_FC1_PWR_MGT |
IEEE80211_FC1_MORE_DATA);
/* 11n: conditionnally mask order bit */
if (ieee80211_has_htc(wh))
*aad &= ~IEEE80211_FC1_ORDER;
aad++;
IEEE80211_ADDR_COPY(aad, wh->i_addr1); aad += IEEE80211_ADDR_LEN;
IEEE80211_ADDR_COPY(aad, wh->i_addr2); aad += IEEE80211_ADDR_LEN;
IEEE80211_ADDR_COPY(aad, wh->i_addr3); aad += IEEE80211_ADDR_LEN;
*aad++ = wh->i_seq[0] & ~0xf0;
*aad++ = 0;
if (ieee80211_has_addr4(wh)) {
IEEE80211_ADDR_COPY(aad,
((const struct ieee80211_frame_addr4 *)wh)->i_addr4);
aad += IEEE80211_ADDR_LEN;
}
if (ieee80211_has_qos(wh)) {
*aad++ = tid = ieee80211_get_qos(wh) & IEEE80211_QOS_TID;
*aad++ = 0;
}
/* construct CCM nonce */
nonce[ 0] = tid;
if ((wh->i_fc[0] & IEEE80211_FC0_TYPE_MASK) ==
IEEE80211_FC0_TYPE_MGT)
nonce[0] |= 1 << 4; /* 11w: set management bit */
IEEE80211_ADDR_COPY(&nonce[1], wh->i_addr2);
nonce[ 7] = pn >> 40; /* PN5 */
nonce[ 8] = pn >> 32; /* PN4 */
nonce[ 9] = pn >> 24; /* PN3 */
nonce[10] = pn >> 16; /* PN2 */
nonce[11] = pn >> 8; /* PN1 */
nonce[12] = pn; /* PN0 */
/* add 2 authentication blocks (including l(a) and padded AAD) */
la = aad - &auth[2]; /* fill l(a) */
auth[0] = la >> 8;
auth[1] = la & 0xff;
memset(aad, 0, 30 - la); /* pad AAD with zeros */
/* construct first block B_0 */
b[ 0] = 89; /* Flags = 64*Adata + 8*((M-2)/2) + (L-1) */
memcpy(&b[1], nonce, 13);
b[14] = lm >> 8;
b[15] = lm & 0xff;
rijndael_encrypt(ctx, b, b);
for (i = 0; i < 16; i++)
b[i] ^= auth[i];
rijndael_encrypt(ctx, b, b);
for (i = 0; i < 16; i++)
b[i] ^= auth[16 + i];
rijndael_encrypt(ctx, b, b);
/* construct S_0 */
a[ 0] = 1; /* Flags = L' = (L-1) */
memcpy(&a[1], nonce, 13);
a[14] = a[15] = 0;
rijndael_encrypt(ctx, a, s0);
}
struct mbuf *
ieee80211_ccmp_encrypt(struct ieee80211com *ic, struct mbuf *m0,
struct ieee80211_key *k)
{
struct ieee80211_ccmp_ctx *ctx = k->k_priv;
const struct ieee80211_frame *wh;
const u_int8_t *src;
u_int8_t *ivp, *mic, *dst;
u_int8_t a[16], b[16], s0[16], s[16];
struct mbuf *n0, *m, *n;
int hdrlen, left, moff, noff, len;
u_int16_t ctr;
int i, j;
MGET(n0, M_DONTWAIT, m0->m_type);
if (n0 == NULL)
goto nospace;
M_DUP_PKTHDR(n0, m0);
n0->m_pkthdr.len += IEEE80211_CCMP_HDRLEN;
n0->m_len = MHLEN;
if (n0->m_pkthdr.len >= MINCLSIZE - IEEE80211_CCMP_MICLEN) {
MCLGET(n0, M_DONTWAIT);
if (n0->m_flags & M_EXT)
n0->m_len = n0->m_ext.ext_size;
}
if (n0->m_len > n0->m_pkthdr.len)
n0->m_len = n0->m_pkthdr.len;
/* copy 802.11 header */
wh = mtod(m0, struct ieee80211_frame *);
hdrlen = ieee80211_get_hdrlen(wh);
memcpy(mtod(n0, caddr_t), wh, hdrlen);
k->k_tsc++; /* increment the 48-bit PN */
/* construct CCMP header */
ivp = mtod(n0, u_int8_t *) + hdrlen;
ivp[0] = k->k_tsc; /* PN0 */
ivp[1] = k->k_tsc >> 8; /* PN1 */
ivp[2] = 0; /* Rsvd */
ivp[3] = k->k_id << 6 | IEEE80211_WEP_EXTIV; /* KeyID | ExtIV */
ivp[4] = k->k_tsc >> 16; /* PN2 */
ivp[5] = k->k_tsc >> 24; /* PN3 */
ivp[6] = k->k_tsc >> 32; /* PN4 */
ivp[7] = k->k_tsc >> 40; /* PN5 */
/* construct initial B, A and S_0 blocks */
ieee80211_ccmp_phase1(&ctx->rijndael, wh, k->k_tsc,
m0->m_pkthdr.len - hdrlen, b, a, s0);
/* construct S_1 */
ctr = 1;
a[14] = ctr >> 8;
a[15] = ctr & 0xff;
rijndael_encrypt(&ctx->rijndael, a, s);
/* encrypt frame body and compute MIC */
j = 0;
m = m0;
n = n0;
moff = hdrlen;
noff = hdrlen + IEEE80211_CCMP_HDRLEN;
left = m0->m_pkthdr.len - moff;
while (left > 0) {
if (moff == m->m_len) {
/* nothing left to copy from m */
m = m->m_next;
moff = 0;
}
if (noff == n->m_len) {
/* n is full and there's more data to copy */
MGET(n->m_next, M_DONTWAIT, n->m_type);
if (n->m_next == NULL)
goto nospace;
n = n->m_next;
n->m_len = MLEN;
if (left >= MINCLSIZE - IEEE80211_CCMP_MICLEN) {
MCLGET(n, M_DONTWAIT);
if (n->m_flags & M_EXT)
n->m_len = n->m_ext.ext_size;
}
if (n->m_len > left)
n->m_len = left;
noff = 0;
}
len = min(m->m_len - moff, n->m_len - noff);
src = mtod(m, u_int8_t *) + moff;
dst = mtod(n, u_int8_t *) + noff;
for (i = 0; i < len; i++) {
/* update MIC with clear text */
b[j] ^= src[i];
/* encrypt message */
dst[i] = src[i] ^ s[j];
if (++j < 16)
continue;
/* we have a full block, encrypt MIC */
rijndael_encrypt(&ctx->rijndael, b, b);
/* construct a new S_ctr block */
ctr++;
a[14] = ctr >> 8;
a[15] = ctr & 0xff;
rijndael_encrypt(&ctx->rijndael, a, s);
j = 0;
}
moff += len;
noff += len;
left -= len;
}
if (j != 0) /* partial block, encrypt MIC */
rijndael_encrypt(&ctx->rijndael, b, b);
/* reserve trailing space for MIC */
if (M_TRAILINGSPACE(n) < IEEE80211_CCMP_MICLEN) {
MGET(n->m_next, M_DONTWAIT, n->m_type);
if (n->m_next == NULL)
goto nospace;
n = n->m_next;
n->m_len = 0;
}
/* finalize MIC, U := T XOR first-M-bytes( S_0 ) */
mic = mtod(n, u_int8_t *) + n->m_len;
for (i = 0; i < IEEE80211_CCMP_MICLEN; i++)
mic[i] = b[i] ^ s0[i];
n->m_len += IEEE80211_CCMP_MICLEN;
n0->m_pkthdr.len += IEEE80211_CCMP_MICLEN;
m_freem(m0);
return n0;
nospace:
ic->ic_stats.is_tx_nombuf++;
m_freem(m0);
if (n0 != NULL)
m_freem(n0);
return NULL;
}
struct mbuf *
ieee80211_ccmp_decrypt(struct ieee80211com *ic, struct mbuf *m0,
struct ieee80211_key *k)
{
struct ieee80211_ccmp_ctx *ctx = k->k_priv;
struct ieee80211_frame *wh;
u_int64_t pn, *prsc;
const u_int8_t *ivp, *src;
u_int8_t *dst;
u_int8_t mic0[IEEE80211_CCMP_MICLEN];
u_int8_t a[16], b[16], s0[16], s[16];
struct mbuf *n0, *m, *n;
int hdrlen, left, moff, noff, len;
u_int16_t ctr;
int i, j;
wh = mtod(m0, struct ieee80211_frame *);
hdrlen = ieee80211_get_hdrlen(wh);
ivp = (u_int8_t *)wh + hdrlen;
if (m0->m_pkthdr.len < hdrlen + IEEE80211_CCMP_HDRLEN +
IEEE80211_CCMP_MICLEN) {
m_freem(m0);
return NULL;
}
/* check that ExtIV bit is set */
if (!(ivp[3] & IEEE80211_WEP_EXTIV)) {
m_freem(m0);
return NULL;
}
/* retrieve last seen packet number for this frame type/priority */
if ((wh->i_fc[0] & IEEE80211_FC0_TYPE_MASK) ==
IEEE80211_FC0_TYPE_DATA) {
u_int8_t tid = ieee80211_has_qos(wh) ?
ieee80211_get_qos(wh) & IEEE80211_QOS_TID : 0;
prsc = &k->k_rsc[tid];
} else /* 11w: management frames have their own counters */
prsc = &k->k_mgmt_rsc;
/* extract the 48-bit PN from the CCMP header */
pn = (u_int64_t)ivp[0] |
(u_int64_t)ivp[1] << 8 |
(u_int64_t)ivp[4] << 16 |
(u_int64_t)ivp[5] << 24 |
(u_int64_t)ivp[6] << 32 |
(u_int64_t)ivp[7] << 40;
if (pn <= *prsc) {
/* replayed frame, discard */
ic->ic_stats.is_ccmp_replays++;
m_freem(m0);
return NULL;
}
MGET(n0, M_DONTWAIT, m0->m_type);
if (n0 == NULL)
goto nospace;
M_DUP_PKTHDR(n0, m0);
n0->m_pkthdr.len -= IEEE80211_CCMP_HDRLEN + IEEE80211_CCMP_MICLEN;
n0->m_len = MHLEN;
if (n0->m_pkthdr.len >= MINCLSIZE) {
MCLGET(n0, M_DONTWAIT);
if (n0->m_flags & M_EXT)
n0->m_len = n0->m_ext.ext_size;
}
if (n0->m_len > n0->m_pkthdr.len)
n0->m_len = n0->m_pkthdr.len;
/* construct initial B, A and S_0 blocks */
ieee80211_ccmp_phase1(&ctx->rijndael, wh, pn,
n0->m_pkthdr.len - hdrlen, b, a, s0);
/* copy 802.11 header and clear protected bit */
memcpy(mtod(n0, caddr_t), wh, hdrlen);
wh = mtod(n0, struct ieee80211_frame *);
wh->i_fc[1] &= ~IEEE80211_FC1_PROTECTED;
/* construct S_1 */
ctr = 1;
a[14] = ctr >> 8;
a[15] = ctr & 0xff;
rijndael_encrypt(&ctx->rijndael, a, s);
/* decrypt frame body and compute MIC */
j = 0;
m = m0;
n = n0;
moff = hdrlen + IEEE80211_CCMP_HDRLEN;
noff = hdrlen;
left = n0->m_pkthdr.len - noff;
while (left > 0) {
if (moff == m->m_len) {
/* nothing left to copy from m */
m = m->m_next;
moff = 0;
}
if (noff == n->m_len) {
/* n is full and there's more data to copy */
MGET(n->m_next, M_DONTWAIT, n->m_type);
if (n->m_next == NULL)
goto nospace;
n = n->m_next;
n->m_len = MLEN;
if (left >= MINCLSIZE) {
MCLGET(n, M_DONTWAIT);
if (n->m_flags & M_EXT)
n->m_len = n->m_ext.ext_size;
}
if (n->m_len > left)
n->m_len = left;
noff = 0;
}
len = min(m->m_len - moff, n->m_len - noff);
src = mtod(m, u_int8_t *) + moff;
dst = mtod(n, u_int8_t *) + noff;
for (i = 0; i < len; i++) {
/* decrypt message */
dst[i] = src[i] ^ s[j];
/* update MIC with clear text */
b[j] ^= dst[i];
if (++j < 16)
continue;
/* we have a full block, encrypt MIC */
rijndael_encrypt(&ctx->rijndael, b, b);
/* construct a new S_ctr block */
ctr++;
a[14] = ctr >> 8;
a[15] = ctr & 0xff;
rijndael_encrypt(&ctx->rijndael, a, s);
j = 0;
}
moff += len;
noff += len;
left -= len;
}
if (j != 0) /* partial block, encrypt MIC */
rijndael_encrypt(&ctx->rijndael, b, b);
/* finalize MIC, U := T XOR first-M-bytes( S_0 ) */
for (i = 0; i < IEEE80211_CCMP_MICLEN; i++)
b[i] ^= s0[i];
/* check that it matches the MIC in received frame */
m_copydata(m, moff, IEEE80211_CCMP_MICLEN, mic0);
if (memcmp(mic0, b, IEEE80211_CCMP_MICLEN) != 0) {
ic->ic_stats.is_ccmp_dec_errs++;
m_freem(m0);
m_freem(n0);
return NULL;
}
/* update last seen packet number (MIC is validated) */
*prsc = pn;
m_freem(m0);
return n0;
nospace:
ic->ic_stats.is_rx_nombuf++;
m_freem(m0);
if (n0 != NULL)
m_freem(n0);
return NULL;
}