ppp: backport security fixes

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>

3 files changed, 128 insertions, 0 deletions

diff --git a/package/network/services/ppp/patches/700-radius-Prevent-buffer-overflow-in-rc_mksid.patch b/package/network/services/ppp/patches/700-radius-Prevent-buffer-overflow-in-rc_mksid.patch
new file mode 100644
index 0000000000..1c5722e6dd
--- /dev/null
+++ b/package/network/services/ppp/patches/700-radius-Prevent-buffer-overflow-in-rc_mksid.patch
@@ -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);
diff --git a/package/network/services/ppp/patches/701-pppd-Fix-bounds-check-in-EAP-code.patch b/package/network/services/ppp/patches/701-pppd-Fix-bounds-check-in-EAP-code.patch
new file mode 100644
index 0000000000..c2ca9729ec
--- /dev/null
+++ b/package/network/services/ppp/patches/701-pppd-Fix-bounds-check-in-EAP-code.patch
@@ -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';
diff --git a/package/network/services/ppp/patches/702-pppd-Ignore-received-EAP-messages-when-not-doing-EAP.patch b/package/network/services/ppp/patches/702-pppd-Ignore-received-EAP-messages-when-not-doing-EAP.patch
new file mode 100644
index 0000000000..7286d81a56
--- /dev/null
+++ b/package/network/services/ppp/patches/702-pppd-Ignore-received-EAP-messages-when-not-doing-EAP.patch
@@ -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),