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ppp: backport security fixes

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8d45443bb5c9 pppd: Ignore received EAP messages when not doing EAP
8d7970b8f3db pppd: Fix bounds check in EAP code
858976b1fc31 radius: Prevent buffer overflow in rc_mksid()

Signed-off-by: Petr Štetiar <ynezz@true.cz>
Fixes: CVE-2020-8597
Signed-off-by: Jo-Philipp Wich <jo@mein.io>
This commit is contained in:
Petr Štetiar 2020-02-20 09:03:54 +01:00 committed by Jo-Philipp Wich
parent 817e775319
commit 35890514bb
4 changed files with 129 additions and 1 deletions
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2
package/network/services/ppp/Makefile
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@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
include $(INCLUDE_DIR)/kernel.mk
PKG_NAME:=ppp
PKG_RELEASE:=1
PKG_RELEASE:=2
PKG_SOURCE_PROTO:=git
PKG_SOURCE_URL:=https://github.com/paulusmack/ppp

30
package/network/services/ppp/patches/700-radius-Prevent-buffer-overflow-in-rc_mksid.patch Normal file
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@ -0,0 +1,30 @@
From 858976b1fc3107f1261aae337831959b511b83c2 Mon Sep 17 00:00:00 2001
From: Paul Mackerras <paulus@ozlabs.org>
Date: Sat, 4 Jan 2020 12:01:32 +1100
Subject: [PATCH] radius: Prevent buffer overflow in rc_mksid()
On some systems getpid() can return a value greater than 65535.
Increase the size of buf[] to allow for this, and use slprintf()
to make sure we never overflow it.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
---
pppd/plugins/radius/util.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/pppd/plugins/radius/util.c b/pppd/plugins/radius/util.c
index 6f976a712951..740131e8377c 100644
--- a/pppd/plugins/radius/util.c
+++ b/pppd/plugins/radius/util.c
@@ -73,9 +73,9 @@ void rc_mdelay(int msecs)
char *
rc_mksid (void)
{
- static char buf[15];
+ static char buf[32];
static unsigned short int cnt = 0;
- sprintf (buf, "%08lX%04X%02hX",
+ slprintf(buf, sizeof(buf), "%08lX%04X%02hX",
(unsigned long int) time (NULL),
(unsigned int) getpid (),
cnt & 0xFF);

37
package/network/services/ppp/patches/701-pppd-Fix-bounds-check-in-EAP-code.patch Normal file
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@ -0,0 +1,37 @@
From 8d7970b8f3db727fe798b65f3377fe6787575426 Mon Sep 17 00:00:00 2001
From: Paul Mackerras <paulus@ozlabs.org>
Date: Mon, 3 Feb 2020 15:53:28 +1100
Subject: [PATCH] pppd: Fix bounds check in EAP code
Given that we have just checked vallen < len, it can never be the case
that vallen >= len + sizeof(rhostname). This fixes the check so we
actually avoid overflowing the rhostname array.
Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
---
pppd/eap.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/pppd/eap.c b/pppd/eap.c
index 94407f56a336..1b93db01aebd 100644
--- a/pppd/eap.c
+++ b/pppd/eap.c
@@ -1420,7 +1420,7 @@ int len;
}
/* Not so likely to happen. */
- if (vallen >= len + sizeof (rhostname)) {
+ if (len - vallen >= sizeof (rhostname)) {
dbglog("EAP: trimming really long peer name down");
BCOPY(inp + vallen, rhostname, sizeof (rhostname) - 1);
rhostname[sizeof (rhostname) - 1] = '\0';
@@ -1846,7 +1846,7 @@ int len;
}
/* Not so likely to happen. */
- if (vallen >= len + sizeof (rhostname)) {
+ if (len - vallen >= sizeof (rhostname)) {
dbglog("EAP: trimming really long peer name down");
BCOPY(inp + vallen, rhostname, sizeof (rhostname) - 1);
rhostname[sizeof (rhostname) - 1] = '\0';

61
package/network/services/ppp/patches/702-pppd-Ignore-received-EAP-messages-when-not-doing-EAP.patch Normal file
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@ -0,0 +1,61 @@
From 8d45443bb5c9372b4c6a362ba2f443d41c5636af Mon Sep 17 00:00:00 2001
From: Paul Mackerras <paulus@ozlabs.org>
Date: Mon, 3 Feb 2020 16:31:42 +1100
Subject: [PATCH] pppd: Ignore received EAP messages when not doing EAP
This adds some basic checks to the subroutines of eap_input to check
that we have requested or agreed to doing EAP authentication before
doing any processing on the received packet. The motivation is to
make it harder for a malicious peer to disrupt the operation of pppd
by sending unsolicited EAP packets. Note that eap_success() already
has a check that the EAP client state is reasonable, and does nothing
(apart from possibly printing a debug message) if not.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
---
pppd/eap.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/pppd/eap.c b/pppd/eap.c
index 1b93db01aebd..082e95343120 100644
--- a/pppd/eap.c
+++ b/pppd/eap.c
@@ -1328,6 +1328,12 @@ int len;
int fd;
#endif /* USE_SRP */
+ /*
+ * Ignore requests if we're not open
+ */
+ if (esp->es_client.ea_state <= eapClosed)
+ return;
+
/*
* Note: we update es_client.ea_id *only if* a Response
* message is being generated. Otherwise, we leave it the
@@ -1736,6 +1742,12 @@ int len;
u_char dig[SHA_DIGESTSIZE];
#endif /* USE_SRP */
+ /*
+ * Ignore responses if we're not open
+ */
+ if (esp->es_server.ea_state <= eapClosed)
+ return;
+
if (esp->es_server.ea_id != id) {
dbglog("EAP: discarding Response %d; expected ID %d", id,
esp->es_server.ea_id);
@@ -2047,6 +2059,12 @@ u_char *inp;
int id;
int len;
{
+ /*
+ * Ignore failure messages if we're not open
+ */
+ if (esp->es_client.ea_state <= eapClosed)
+ return;
+
if (!eap_client_active(esp)) {
dbglog("EAP unexpected failure message in state %s (%d)",
eap_state_name(esp->es_client.ea_state),