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net80211: prevent plaintext injection by A-MSDU RFC1042/EAPOL frames

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No longer accept plaintext A-MSDU frames that start with an RFC1042
header with EtherType EAPOL.  This is done by only accepting EAPOL
packets that are included in non-aggregated 802.11 frames.

Note that before this patch, FreeBSD also only accepted EAPOL frames
that are sent in a non-aggregated 802.11 frame due to bugs in
processing EAPOL packets inside A-MSDUs. In other words,
compatibility with legitimate devices remains the same.

This relates to section 6.5 in the 2021 Usenix "FragAttacks" (Fragment
and Forge: Breaking Wi-Fi Through Frame Aggregation and Fragmentation)
paper.

Submitted by:	Mathy Vanhoef (Mathy.Vanhoef kuleuven.be)
Security:	CVE-2020-26144
PR:		256120
MFC after:	7 days
Differential Revision: https://reviews.freebsd.org/D30665
This commit is contained in:
Mathy Vanhoef 2021-06-06 22:10:56 +00:00 committed by Bjoern A. Zeeb
parent f024bdf115
commit ffc19cf52d
4 changed files with 48 additions and 24 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

18
sys/net80211/ieee80211_adhoc.c
View file

@ -571,7 +571,10 @@ adhoc_input(struct ieee80211_node *ni, struct mbuf *m,
IEEE80211_NODE_STAT(ni, rx_decap);
goto err;
}
eh = mtod(m, struct ether_header *);
if (!(qos & IEEE80211_QOS_AMSDU))
eh = mtod(m, struct ether_header *);
else
eh = NULL;
if (!ieee80211_node_is_authorized(ni)) {
/*
* Deny any non-PAE frames received prior to
@ -581,11 +584,13 @@ adhoc_input(struct ieee80211_node *ni, struct mbuf *m,
* the port is not marked authorized by the
* authenticator until the handshake has completed.
*/
if (eh->ether_type != htons(ETHERTYPE_PAE)) {
if (eh == NULL ||
eh->ether_type != htons(ETHERTYPE_PAE)) {
IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_INPUT,
eh->ether_shost, "data",
"unauthorized port: ether type 0x%x len %u",
eh->ether_type, m->m_pkthdr.len);
ni->ni_macaddr, "data", "unauthorized or "
"unknown port: ether type 0x%x len %u",
eh == NULL ? -1 : eh->ether_type,
m->m_pkthdr.len);
vap->iv_stats.is_rx_unauth++;
IEEE80211_NODE_STAT(ni, rx_unauth);
goto err;
@ -598,7 +603,8 @@ adhoc_input(struct ieee80211_node *ni, struct mbuf *m,
if ((vap->iv_flags & IEEE80211_F_DROPUNENC) &&
((has_decrypted == 0) && (m->m_flags & M_WEP) == 0) &&
(is_hw_decrypted == 0) &&
eh->ether_type != htons(ETHERTYPE_PAE)) {
(eh == NULL ||
eh->ether_type != htons(ETHERTYPE_PAE))) {
/*
* Drop unencrypted frames.
*/

18
sys/net80211/ieee80211_hostap.c
View file

@ -757,7 +757,10 @@ hostap_input(struct ieee80211_node *ni, struct mbuf *m,
IEEE80211_NODE_STAT(ni, rx_decap);
goto err;
}
eh = mtod(m, struct ether_header *);
if (!(qos & IEEE80211_QOS_AMSDU))
eh = mtod(m, struct ether_header *);
else
eh = NULL;
if (!ieee80211_node_is_authorized(ni)) {
/*
* Deny any non-PAE frames received prior to
@ -767,11 +770,13 @@ hostap_input(struct ieee80211_node *ni, struct mbuf *m,
* the port is not marked authorized by the
* authenticator until the handshake has completed.
*/
if (eh->ether_type != htons(ETHERTYPE_PAE)) {
if (eh == NULL ||
eh->ether_type != htons(ETHERTYPE_PAE)) {
IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_INPUT,
eh->ether_shost, "data",
"unauthorized port: ether type 0x%x len %u",
eh->ether_type, m->m_pkthdr.len);
ni->ni_macaddr, "data", "unauthorized or "
"unknown port: ether type 0x%x len %u",
eh == NULL ? -1 : eh->ether_type,
m->m_pkthdr.len);
vap->iv_stats.is_rx_unauth++;
IEEE80211_NODE_STAT(ni, rx_unauth);
goto err;
@ -784,7 +789,8 @@ hostap_input(struct ieee80211_node *ni, struct mbuf *m,
if ((vap->iv_flags & IEEE80211_F_DROPUNENC) &&
((has_decrypted == 0) && (m->m_flags & M_WEP) == 0) &&
(is_hw_decrypted == 0) &&
eh->ether_type != htons(ETHERTYPE_PAE)) {
(eh == NULL ||
eh->ether_type != htons(ETHERTYPE_PAE))) {
/*
* Drop unencrypted frames.
*/

18
sys/net80211/ieee80211_sta.c
View file

@ -840,7 +840,10 @@ sta_input(struct ieee80211_node *ni, struct mbuf *m,
IEEE80211_NODE_STAT(ni, rx_decap);
goto err;
}
eh = mtod(m, struct ether_header *);
if (!(qos & IEEE80211_QOS_AMSDU))
eh = mtod(m, struct ether_header *);
else
eh = NULL;
if (!ieee80211_node_is_authorized(ni)) {
/*
* Deny any non-PAE frames received prior to
@ -850,11 +853,13 @@ sta_input(struct ieee80211_node *ni, struct mbuf *m,
* the port is not marked authorized by the
* authenticator until the handshake has completed.
*/
if (eh->ether_type != htons(ETHERTYPE_PAE)) {
if (eh == NULL ||
eh->ether_type != htons(ETHERTYPE_PAE)) {
IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_INPUT,
eh->ether_shost, "data",
"unauthorized port: ether type 0x%x len %u",
eh->ether_type, m->m_pkthdr.len);
ni->ni_macaddr, "data", "unauthorized or "
"unknown port: ether type 0x%x len %u",
eh == NULL ? -1 : eh->ether_type,
m->m_pkthdr.len);
vap->iv_stats.is_rx_unauth++;
IEEE80211_NODE_STAT(ni, rx_unauth);
goto err;
@ -867,7 +872,8 @@ sta_input(struct ieee80211_node *ni, struct mbuf *m,
if ((vap->iv_flags & IEEE80211_F_DROPUNENC) &&
((has_decrypted == 0) && (m->m_flags & M_WEP) == 0) &&
(is_hw_decrypted == 0) &&
eh->ether_type != htons(ETHERTYPE_PAE)) {
(eh == NULL ||
eh->ether_type != htons(ETHERTYPE_PAE))) {
/*
* Drop unencrypted frames.
*/

18
sys/net80211/ieee80211_wds.c
View file

@ -634,7 +634,10 @@ wds_input(struct ieee80211_node *ni, struct mbuf *m,
IEEE80211_NODE_STAT(ni, rx_decap);
goto err;
}
eh = mtod(m, struct ether_header *);
if (!(qos & IEEE80211_QOS_AMSDU))
eh = mtod(m, struct ether_header *);
else
eh = NULL;
if (!ieee80211_node_is_authorized(ni)) {
/*
* Deny any non-PAE frames received prior to
@ -644,11 +647,13 @@ wds_input(struct ieee80211_node *ni, struct mbuf *m,
* the port is not marked authorized by the
* authenticator until the handshake has completed.
*/
if (eh->ether_type != htons(ETHERTYPE_PAE)) {
if (eh == NULL ||
eh->ether_type != htons(ETHERTYPE_PAE)) {
IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_INPUT,
eh->ether_shost, "data",
"unauthorized port: ether type 0x%x len %u",
eh->ether_type, m->m_pkthdr.len);
ni->ni_macaddr, "data", "unauthorized or "
"unknown port: ether type 0x%x len %u",
eh == NULL ? -1 : eh->ether_type,
m->m_pkthdr.len);
vap->iv_stats.is_rx_unauth++;
IEEE80211_NODE_STAT(ni, rx_unauth);
goto err;
@ -661,7 +666,8 @@ wds_input(struct ieee80211_node *ni, struct mbuf *m,
if ((vap->iv_flags & IEEE80211_F_DROPUNENC) &&
((has_decrypted == 0) && (m->m_flags & M_WEP) == 0) &&
(is_hw_decrypted == 0) &&
eh->ether_type != htons(ETHERTYPE_PAE)) {
(eh == NULL ||
eh->ether_type != htons(ETHERTYPE_PAE))) {
/*
* Drop unencrypted frames.
*/