From: Johannes Berg <johannes.berg(a)intel.com>
EAPOL frames are used for authentication and key management between the
AP and each individual STA associated in the BSS. Those frames are not
supposed to be sent by one associated STA to another associated STA
(either unicast for broadcast/multicast).
Similarly, in 802.11 they're supposed to be sent to the authenticator
(AP) address.
Since it is possible for unexpected EAPOL frames to result in misbehavior
in supplicant implementations, it is better for the AP to not allow such
cases to be forwarded to other clients either directly, or indirectly if
the AP interface is part of a bridge.
Accept EAPOL (control port) frames only if they're transmitted to the
own address, or, due to interoperability concerns, to the PAE group
address.
Disable forwarding of EAPOL (or well, the configured control port
protocol) frames back to wireless medium in all cases. Previously, these
frames were accepted from fully authenticated and authorized stations
and also from unauthenticated stations for one of the cases.
Additionally, to avoid forwarding by the bridge, rewrite the PAE group
address case to the local MAC address.
Cc: stable(a)vger.kernel.org
Co-developed-by: Jouni Malinen <jouni(a)codeaurora.org>
Signed-off-by: Jouni Malinen <jouni(a)codeaurora.org>
Signed-off-by: Johannes Berg <johannes.berg(a)intel.com>
---
net/mac80211/rx.c | 33 +++++++++++++++++++++++++++------
1 file changed, 27 insertions(+), 6 deletions(-)
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 4454ec47283f..22a925899a9e 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2531,13 +2531,13 @@ static bool ieee80211_frame_allowed(struct ieee80211_rx_data *rx, __le16 fc)
struct ethhdr *ehdr = (struct ethhdr *) rx->skb->data;
/*
- * Allow EAPOL frames to us/the PAE group address regardless
- * of whether the frame was encrypted or not.
+ * Allow EAPOL frames to us/the PAE group address regardless of
+ * whether the frame was encrypted or not, and always disallow
+ * all other destination addresses for them.
*/
- if (ehdr->h_proto == rx->sdata->control_port_protocol &&
- (ether_addr_equal(ehdr->h_dest, rx->sdata->vif.addr) ||
- ether_addr_equal(ehdr->h_dest, pae_group_addr)))
- return true;
+ if (unlikely(ehdr->h_proto == rx->sdata->control_port_protocol))
+ return ether_addr_equal(ehdr->h_dest, rx->sdata->vif.addr) ||
+ ether_addr_equal(ehdr->h_dest, pae_group_addr);
if (ieee80211_802_1x_port_control(rx) ||
ieee80211_drop_unencrypted(rx, fc))
@@ -2562,8 +2562,28 @@ static void ieee80211_deliver_skb_to_local_stack(struct sk_buff *skb,
cfg80211_rx_control_port(dev, skb, noencrypt);
dev_kfree_skb(skb);
} else {
+ struct ethhdr *ehdr = (void *)skb_mac_header(skb);
+
memset(skb->cb, 0, sizeof(skb->cb));
+ /*
+ * 802.1X over 802.11 requires that the authenticator address
+ * be used for EAPOL frames. However, 802.1X allows the use of
+ * the PAE group address instead. If the interface is part of
+ * a bridge and we pass the frame with the PAE group address,
+ * then the bridge will forward it to the network (even if the
+ * client was not associated yet), which isn't supposed to
+ * happen.
+ * To avoid that, rewrite the destination address to our own
+ * address, so that the authenticator (e.g. hostapd) will see
+ * the frame, but bridge won't forward it anywhere else. Note
+ * that due to earlier filtering, the only other address can
+ * be the PAE group address.
+ */
+ if (unlikely(skb->protocol == sdata->control_port_protocol &&
+ !ether_addr_equal(ehdr->h_dest, sdata->vif.addr)))
+ ether_addr_copy(ehdr->h_dest, sdata->vif.addr);
+
/* deliver to local stack */
if (rx->list)
list_add_tail(&skb->list, rx->list);
@@ -2603,6 +2623,7 @@ ieee80211_deliver_skb(struct ieee80211_rx_data *rx)
if ((sdata->vif.type == NL80211_IFTYPE_AP ||
sdata->vif.type == NL80211_IFTYPE_AP_VLAN) &&
!(sdata->flags & IEEE80211_SDATA_DONT_BRIDGE_PACKETS) &&
+ ehdr->h_proto != rx->sdata->control_port_protocol &&
(sdata->vif.type != NL80211_IFTYPE_AP_VLAN || !sdata->u.vlan.sta)) {
if (is_multicast_ether_addr(ehdr->h_dest) &&
ieee80211_vif_get_num_mcast_if(sdata) != 0) {
--
2.30.2
From: Johannes Berg <johannes.berg(a)intel.com>
Similar to the issues fixed in previous patches, TKIP and WEP
should be protected even if for TKIP we have the Michael MIC
protecting it, and WEP is broken anyway.
However, this also somewhat protects potential other algorithms
that drivers might implement.
Cc: stable(a)vger.kernel.org
Signed-off-by: Johannes Berg <johannes.berg(a)intel.com>
---
net/mac80211/rx.c | 12 ++++++++++++
net/mac80211/sta_info.h | 3 ++-
2 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index b619c47e1d12..4454ec47283f 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2274,6 +2274,7 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
* next fragment has a sequential PN value.
*/
entry->check_sequential_pn = true;
+ entry->is_protected = true;
entry->key_color = rx->key->color;
memcpy(entry->last_pn,
rx->key->u.ccmp.rx_pn[queue],
@@ -2286,6 +2287,9 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
sizeof(rx->key->u.gcmp.rx_pn[queue]));
BUILD_BUG_ON(IEEE80211_CCMP_PN_LEN !=
IEEE80211_GCMP_PN_LEN);
+ } else if (rx->key && ieee80211_has_protected(fc)) {
+ entry->is_protected = true;
+ entry->key_color = rx->key->color;
}
return RX_QUEUED;
}
@@ -2327,6 +2331,14 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
if (memcmp(pn, rpn, IEEE80211_CCMP_PN_LEN))
return RX_DROP_UNUSABLE;
memcpy(entry->last_pn, pn, IEEE80211_CCMP_PN_LEN);
+ } else if (entry->is_protected &&
+ (!rx->key || !ieee80211_has_protected(fc) ||
+ rx->key->color != entry->key_color)) {
+ /* Drop this as a mixed key or fragment cache attack, even
+ * if for TKIP Michael MIC should protect us, and WEP is a
+ * lost cause anyway.
+ */
+ return RX_DROP_UNUSABLE;
}
skb_pull(rx->skb, ieee80211_hdrlen(fc));
diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index 5c56d29a619e..0333072ebd98 100644
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -455,7 +455,8 @@ struct ieee80211_fragment_entry {
u16 extra_len;
u16 last_frag;
u8 rx_queue;
- bool check_sequential_pn; /* needed for CCMP/GCMP */
+ u8 check_sequential_pn:1, /* needed for CCMP/GCMP */
+ is_protected:1;
u8 last_pn[6]; /* PN of the last fragment if CCMP was used */
unsigned int key_color;
};
--
2.30.2
From: Johannes Berg <johannes.berg(a)intel.com>
With old ciphers (WEP and TKIP) we shouldn't be using A-MSDUs
since A-MSDUs are only supported if we know that they are, and
the only practical way for that is HT support which doesn't
support old ciphers.
However, we would normally accept them anyway. Since we check
the MMIC before deaggregating A-MSDUs, and the A-MSDU bit in
the QoS header is not protected in TKIP (or WEP), this enables
attacks similar to CVE-2020-24588. To prevent that, drop A-MSDUs
completely with old ciphers.
Cc: stable(a)vger.kernel.org
Signed-off-by: Johannes Berg <johannes.berg(a)intel.com>
---
net/mac80211/rx.c | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index f14d32a5001d..8a72d48ad6e0 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -6,7 +6,7 @@
* Copyright 2007-2010 Johannes Berg <johannes(a)sipsolutions.net>
* Copyright 2013-2014 Intel Mobile Communications GmbH
* Copyright(c) 2015 - 2017 Intel Deutschland GmbH
- * Copyright (C) 2018-2020 Intel Corporation
+ * Copyright (C) 2018-2021 Intel Corporation
*/
#include <linux/jiffies.h>
@@ -2739,6 +2739,23 @@ ieee80211_rx_h_amsdu(struct ieee80211_rx_data *rx)
if (is_multicast_ether_addr(hdr->addr1))
return RX_DROP_UNUSABLE;
+ if (rx->key) {
+ /*
+ * We should not receive A-MSDUs on pre-HT connections,
+ * and HT connections cannot use old ciphers. Thus drop
+ * them, as in those cases we couldn't even have SPP
+ * A-MSDUs or such.
+ */
+ switch (rx->key->conf.cipher) {
+ case WLAN_CIPHER_SUITE_WEP40:
+ case WLAN_CIPHER_SUITE_WEP104:
+ case WLAN_CIPHER_SUITE_TKIP:
+ return RX_DROP_UNUSABLE;
+ default:
+ break;
+ }
+ }
+
return __ieee80211_rx_h_amsdu(rx, 0);
}
--
2.30.2
From: Mathy Vanhoef <Mathy.Vanhoef(a)kuleuven.be>
Mitigate A-MSDU injection attacks (CVE-2020-24588) by detecting if the
destination address of a subframe equals an RFC1042 (i.e., LLC/SNAP)
header, and if so dropping the complete A-MSDU frame. This mitigates
known attacks, although new (unknown) aggregation-based attacks may
remain possible.
This defense works because in A-MSDU aggregation injection attacks, a
normal encrypted Wi-Fi frame is turned into an A-MSDU frame. This means
the first 6 bytes of the first A-MSDU subframe correspond to an RFC1042
header. In other words, the destination MAC address of the first A-MSDU
subframe contains the start of an RFC1042 header during an aggregation
attack. We can detect this and thereby prevent this specific attack.
For details, see Section 7.2 of "Fragment and Forge: Breaking Wi-Fi
Through Frame Aggregation and Fragmentation".
Note that for kernel 4.9 and above this patch depends on "mac80211:
properly handle A-MSDUs that start with a rfc1042 header". Otherwise
this patch has no impact and attacks will remain possible.
Cc: stable(a)vger.kernel.org
Signed-off-by: Mathy Vanhoef <Mathy.Vanhoef(a)kuleuven.be>
Signed-off-by: Johannes Berg <johannes.berg(a)intel.com>
---
net/wireless/util.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/wireless/util.c b/net/wireless/util.c
index 39966a873e40..7ec021a610ae 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -771,6 +771,9 @@ void ieee80211_amsdu_to_8023s(struct sk_buff *skb, struct sk_buff_head *list,
remaining = skb->len - offset;
if (subframe_len > remaining)
goto purge;
+ /* mitigate A-MSDU aggregation injection attacks */
+ if (ether_addr_equal(eth.h_dest, rfc1042_header))
+ goto purge;
offset += sizeof(struct ethhdr);
last = remaining <= subframe_len + padding;
--
2.30.2
From: Mathy Vanhoef <Mathy.Vanhoef(a)kuleuven.be>
Simultaneously prevent mixed key attacks (CVE-2020-24587) and fragment
cache attacks (CVE-2020-24586). This is accomplished by assigning a
unique color to every key (per interface) and using this to track which
key was used to decrypt a fragment. When reassembling frames, it is
now checked whether all fragments were decrypted using the same key.
To assure that fragment cache attacks are also prevented, the ID that is
assigned to keys is unique even over (re)associations and (re)connects.
This means fragments separated by a (re)association or (re)connect will
not be reassembled. Because mac80211 now also prevents the reassembly of
mixed encrypted and plaintext fragments, all cache attacks are prevented.
Cc: stable(a)vger.kernel.org
Signed-off-by: Mathy Vanhoef <Mathy.Vanhoef(a)kuleuven.be>
Signed-off-by: Johannes Berg <johannes.berg(a)intel.com>
---
net/mac80211/ieee80211_i.h | 1 +
net/mac80211/key.c | 7 +++++++
net/mac80211/key.h | 2 ++
net/mac80211/rx.c | 6 ++++++
4 files changed, 16 insertions(+)
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 8fcbaa1eedf3..874ffe7819e5 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -97,6 +97,7 @@ struct ieee80211_fragment_entry {
u8 rx_queue;
bool check_sequential_pn; /* needed for CCMP/GCMP */
u8 last_pn[6]; /* PN of the last fragment if CCMP was used */
+ unsigned int key_color;
};
diff --git a/net/mac80211/key.c b/net/mac80211/key.c
index 56c068cb49c4..f695fc80088b 100644
--- a/net/mac80211/key.c
+++ b/net/mac80211/key.c
@@ -799,6 +799,7 @@ int ieee80211_key_link(struct ieee80211_key *key,
struct ieee80211_sub_if_data *sdata,
struct sta_info *sta)
{
+ static atomic_t key_color = ATOMIC_INIT(0);
struct ieee80211_key *old_key;
int idx = key->conf.keyidx;
bool pairwise = key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE;
@@ -850,6 +851,12 @@ int ieee80211_key_link(struct ieee80211_key *key,
key->sdata = sdata;
key->sta = sta;
+ /*
+ * Assign a unique ID to every key so we can easily prevent mixed
+ * key and fragment cache attacks.
+ */
+ key->color = atomic_inc_return(&key_color);
+
increment_tailroom_need_count(sdata);
ret = ieee80211_key_replace(sdata, sta, pairwise, old_key, key);
diff --git a/net/mac80211/key.h b/net/mac80211/key.h
index 7ad72e9b4991..1e326c89d721 100644
--- a/net/mac80211/key.h
+++ b/net/mac80211/key.h
@@ -128,6 +128,8 @@ struct ieee80211_key {
} debugfs;
#endif
+ unsigned int color;
+
/*
* key config, must be last because it contains key
* material as variable length member
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 65fc674e27cc..531232b91bc4 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2255,6 +2255,7 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
* next fragment has a sequential PN value.
*/
entry->check_sequential_pn = true;
+ entry->key_color = rx->key->color;
memcpy(entry->last_pn,
rx->key->u.ccmp.rx_pn[queue],
IEEE80211_CCMP_PN_LEN);
@@ -2292,6 +2293,11 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
if (!requires_sequential_pn(rx, fc))
return RX_DROP_UNUSABLE;
+
+ /* Prevent mixed key and fragment cache attacks */
+ if (entry->key_color != rx->key->color)
+ return RX_DROP_UNUSABLE;
+
memcpy(pn, entry->last_pn, IEEE80211_CCMP_PN_LEN);
for (i = IEEE80211_CCMP_PN_LEN - 1; i >= 0; i--) {
pn[i]++;
--
2.30.2
From: Mathy Vanhoef <Mathy.Vanhoef(a)kuleuven.be>
Do not mix plaintext and encrypted fragments in protected Wi-Fi
networks. This fixes CVE-2020-26147.
Previously, an attacker was able to first forward a legitimate encrypted
fragment towards a victim, followed by a plaintext fragment. The
encrypted and plaintext fragment would then be reassembled. For further
details see Section 6.3 and Appendix D in the paper "Fragment and Forge:
Breaking Wi-Fi Through Frame Aggregation and Fragmentation".
Because of this change there are now two equivalent conditions in the
code to determine if a received fragment requires sequential PNs, so we
also move this test to a separate function to make the code easier to
maintain.
Cc: stable(a)vger.kernel.org
Signed-off-by: Mathy Vanhoef <Mathy.Vanhoef(a)kuleuven.be>
Signed-off-by: Johannes Berg <johannes.berg(a)intel.com>
---
net/mac80211/rx.c | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 62047e93e217..65fc674e27cc 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2194,6 +2194,16 @@ ieee80211_reassemble_find(struct ieee80211_sub_if_data *sdata,
return NULL;
}
+static bool requires_sequential_pn(struct ieee80211_rx_data *rx, __le16 fc)
+{
+ return rx->key &&
+ (rx->key->conf.cipher == WLAN_CIPHER_SUITE_CCMP ||
+ rx->key->conf.cipher == WLAN_CIPHER_SUITE_CCMP_256 ||
+ rx->key->conf.cipher == WLAN_CIPHER_SUITE_GCMP ||
+ rx->key->conf.cipher == WLAN_CIPHER_SUITE_GCMP_256) &&
+ ieee80211_has_protected(fc);
+}
+
static ieee80211_rx_result debug_noinline
ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
{
@@ -2238,12 +2248,7 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
/* This is the first fragment of a new frame. */
entry = ieee80211_reassemble_add(rx->sdata, frag, seq,
rx->seqno_idx, &(rx->skb));
- if (rx->key &&
- (rx->key->conf.cipher == WLAN_CIPHER_SUITE_CCMP ||
- rx->key->conf.cipher == WLAN_CIPHER_SUITE_CCMP_256 ||
- rx->key->conf.cipher == WLAN_CIPHER_SUITE_GCMP ||
- rx->key->conf.cipher == WLAN_CIPHER_SUITE_GCMP_256) &&
- ieee80211_has_protected(fc)) {
+ if (requires_sequential_pn(rx, fc)) {
int queue = rx->security_idx;
/* Store CCMP/GCMP PN so that we can verify that the
@@ -2285,11 +2290,7 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
u8 pn[IEEE80211_CCMP_PN_LEN], *rpn;
int queue;
- if (!rx->key ||
- (rx->key->conf.cipher != WLAN_CIPHER_SUITE_CCMP &&
- rx->key->conf.cipher != WLAN_CIPHER_SUITE_CCMP_256 &&
- rx->key->conf.cipher != WLAN_CIPHER_SUITE_GCMP &&
- rx->key->conf.cipher != WLAN_CIPHER_SUITE_GCMP_256))
+ if (!requires_sequential_pn(rx, fc))
return RX_DROP_UNUSABLE;
memcpy(pn, entry->last_pn, IEEE80211_CCMP_PN_LEN);
for (i = IEEE80211_CCMP_PN_LEN - 1; i >= 0; i--) {
--
2.30.2