git: 060c556da720 - releng/12.3 - net80211: reject mixed plaintext/encrypted fragments
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Date: Tue, 15 Mar 2022 18:16:16 UTC
The branch releng/12.3 has been updated by markj:
URL: https://cgit.FreeBSD.org/src/commit/?id=060c556da720145912ac79f67e91ef656f74a78b
commit 060c556da720145912ac79f67e91ef656f74a78b
Author: Mathy Vanhoef <Mathy.Vanhoef@kuleuven.be>
AuthorDate: 2021-06-06 22:10:41 +0000
Commit: Mark Johnston <markj@FreeBSD.org>
CommitDate: 2022-03-15 18:16:01 +0000
net80211: reject mixed plaintext/encrypted fragments
ieee80211_defrag() accepts fragmented 802.11 frames in a protected Wi-Fi
network even when some of the fragments are not encrypted.
Track whether the fragments are encrypted or not and only accept
successive ones if they match the state of the first fragment.
This relates to section 6.3 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-2020-26147
PR: 256118
(cherry picked from commit 11572d7d7fb9802ceb46ea9dc6cbe3bb95373e55)
(cherry picked from commit e13d483c5677d12b52f1c81537d54faa85ed43b9)
(cherry picked from commit 00cd5a2f614ae2cf1daa30cde7f91de9cdde2393)
Approved by: so
Security: FreeBSD-SA-22:02.wifi
---
sys/net80211/ieee80211_adhoc.c | 2 +-
sys/net80211/ieee80211_hostap.c | 2 +-
sys/net80211/ieee80211_input.c | 21 ++++++++++++++++++---
sys/net80211/ieee80211_input.h | 2 +-
sys/net80211/ieee80211_mesh.c | 2 +-
sys/net80211/ieee80211_sta.c | 2 +-
sys/net80211/ieee80211_wds.c | 2 +-
7 files changed, 24 insertions(+), 9 deletions(-)
diff --git a/sys/net80211/ieee80211_adhoc.c b/sys/net80211/ieee80211_adhoc.c
index c97b99425caa..e2164bbb46a1 100644
--- a/sys/net80211/ieee80211_adhoc.c
+++ b/sys/net80211/ieee80211_adhoc.c
@@ -531,7 +531,7 @@ adhoc_input(struct ieee80211_node *ni, struct mbuf *m,
* Next up, any fragmentation.
*/
if (!IEEE80211_IS_MULTICAST(wh->i_addr1)) {
- m = ieee80211_defrag(ni, m, hdrspace);
+ m = ieee80211_defrag(ni, m, hdrspace, has_decrypted);
if (m == NULL) {
/* Fragment dropped or frame not complete yet */
goto out;
diff --git a/sys/net80211/ieee80211_hostap.c b/sys/net80211/ieee80211_hostap.c
index 8c132332f86b..8183d3e9b25a 100644
--- a/sys/net80211/ieee80211_hostap.c
+++ b/sys/net80211/ieee80211_hostap.c
@@ -719,7 +719,7 @@ hostap_input(struct ieee80211_node *ni, struct mbuf *m,
* Next up, any fragmentation.
*/
if (!IEEE80211_IS_MULTICAST(wh->i_addr1)) {
- m = ieee80211_defrag(ni, m, hdrspace);
+ m = ieee80211_defrag(ni, m, hdrspace, has_decrypted);
if (m == NULL) {
/* Fragment dropped or frame not complete yet */
goto out;
diff --git a/sys/net80211/ieee80211_input.c b/sys/net80211/ieee80211_input.c
index 979e9aef9d12..5b2d2c15cc12 100644
--- a/sys/net80211/ieee80211_input.c
+++ b/sys/net80211/ieee80211_input.c
@@ -170,7 +170,8 @@ ieee80211_input_mimo_all(struct ieee80211com *ic, struct mbuf *m)
* XXX should handle 3 concurrent reassemblies per-spec.
*/
struct mbuf *
-ieee80211_defrag(struct ieee80211_node *ni, struct mbuf *m, int hdrspace)
+ieee80211_defrag(struct ieee80211_node *ni, struct mbuf *m, int hdrspace,
+ int has_decrypted)
{
struct ieee80211vap *vap = ni->ni_vap;
struct ieee80211_frame *wh = mtod(m, struct ieee80211_frame *);
@@ -189,6 +190,11 @@ ieee80211_defrag(struct ieee80211_node *ni, struct mbuf *m, int hdrspace)
if (!more_frag && fragno == 0 && ni->ni_rxfrag[0] == NULL)
return m;
+ /* Temporarily set flag to remember if fragment was encrypted. */
+ /* XXX use a non-packet altering storage for this in the future. */
+ if (has_decrypted)
+ wh->i_fc[1] |= IEEE80211_FC1_PROTECTED;
+
/*
* Remove frag to insure it doesn't get reaped by timer.
*/
@@ -219,10 +225,14 @@ ieee80211_defrag(struct ieee80211_node *ni, struct mbuf *m, int hdrspace)
lwh = mtod(mfrag, struct ieee80211_frame *);
last_rxseq = le16toh(*(uint16_t *)lwh->i_seq);
- /* NB: check seq # and frag together */
+ /*
+ * NB: check seq # and frag together. Also check that both
+ * fragments are plaintext or that both are encrypted.
+ */
if (rxseq == last_rxseq+1 &&
IEEE80211_ADDR_EQ(wh->i_addr1, lwh->i_addr1) &&
- IEEE80211_ADDR_EQ(wh->i_addr2, lwh->i_addr2)) {
+ IEEE80211_ADDR_EQ(wh->i_addr2, lwh->i_addr2) &&
+ !((wh->i_fc[1] ^ lwh->i_fc[1]) & IEEE80211_FC1_PROTECTED)) {
/* XXX clear MORE_FRAG bit? */
/* track last seqnum and fragno */
*(uint16_t *) lwh->i_seq = *(uint16_t *) wh->i_seq;
@@ -253,6 +263,11 @@ ieee80211_defrag(struct ieee80211_node *ni, struct mbuf *m, int hdrspace)
ni->ni_rxfrag[0] = mfrag;
mfrag = NULL;
}
+ /* Remember to clear protected flag that was temporarily set. */
+ if (mfrag != NULL) {
+ wh = mtod(mfrag, struct ieee80211_frame *);
+ wh->i_fc[1] &= ~IEEE80211_FC1_PROTECTED;
+ }
return mfrag;
}
diff --git a/sys/net80211/ieee80211_input.h b/sys/net80211/ieee80211_input.h
index 5959319c76d7..ae2b4644cc9e 100644
--- a/sys/net80211/ieee80211_input.h
+++ b/sys/net80211/ieee80211_input.h
@@ -309,7 +309,7 @@ fail:
void ieee80211_deliver_data(struct ieee80211vap *,
struct ieee80211_node *, struct mbuf *);
struct mbuf *ieee80211_defrag(struct ieee80211_node *,
- struct mbuf *, int);
+ struct mbuf *, int, int);
struct mbuf *ieee80211_realign(struct ieee80211vap *, struct mbuf *, size_t);
struct mbuf *ieee80211_decap(struct ieee80211vap *, struct mbuf *, int,
uint8_t);
diff --git a/sys/net80211/ieee80211_mesh.c b/sys/net80211/ieee80211_mesh.c
index 217ce51ee1a2..3c8e371d7c5c 100644
--- a/sys/net80211/ieee80211_mesh.c
+++ b/sys/net80211/ieee80211_mesh.c
@@ -1637,7 +1637,7 @@ mesh_input(struct ieee80211_node *ni, struct mbuf *m,
*/
hdrspace = ieee80211_hdrspace(ic, wh);
if (!IEEE80211_IS_MULTICAST(wh->i_addr1)) {
- m = ieee80211_defrag(ni, m, hdrspace);
+ m = ieee80211_defrag(ni, m, hdrspace, 0);
if (m == NULL) {
/* Fragment dropped or frame not complete yet */
goto out;
diff --git a/sys/net80211/ieee80211_sta.c b/sys/net80211/ieee80211_sta.c
index 56372543a200..42a377f12857 100644
--- a/sys/net80211/ieee80211_sta.c
+++ b/sys/net80211/ieee80211_sta.c
@@ -795,7 +795,7 @@ sta_input(struct ieee80211_node *ni, struct mbuf *m,
* Next up, any fragmentation.
*/
if (!IEEE80211_IS_MULTICAST(wh->i_addr1)) {
- m = ieee80211_defrag(ni, m, hdrspace);
+ m = ieee80211_defrag(ni, m, hdrspace, has_decrypted);
if (m == NULL) {
/* Fragment dropped or frame not complete yet */
goto out;
diff --git a/sys/net80211/ieee80211_wds.c b/sys/net80211/ieee80211_wds.c
index 74cc764b856e..dc0d9f8e1afd 100644
--- a/sys/net80211/ieee80211_wds.c
+++ b/sys/net80211/ieee80211_wds.c
@@ -592,7 +592,7 @@ wds_input(struct ieee80211_node *ni, struct mbuf *m,
* Next up, any fragmentation.
*/
if (!IEEE80211_IS_MULTICAST(wh->i_addr1)) {
- m = ieee80211_defrag(ni, m, hdrspace);
+ m = ieee80211_defrag(ni, m, hdrspace, has_decrypted);
if (m == NULL) {
/* Fragment dropped or frame not complete yet */
goto out;