dhcp: CVE-2015-8605

ISC DHCP allows remote attackers to cause a denial of
service (application crash) via an invalid length field
in a UDP IPv4 packet.

(From OE-Core rev: 43f2cfdf63fb70e3c2da0224221dae63b05477df)

Signed-off-by: Mariano Lopez <mariano.lopez@linux.intel.com>
Signed-off-by: Joshua Lock <joshua.g.lock@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

3 files changed, 234 insertions, 0 deletions

diff --git a/meta/recipes-connectivity/dhcp/dhcp/CVE-2015-8605.patch b/meta/recipes-connectivity/dhcp/dhcp/CVE-2015-8605.patch
new file mode 100644
index 0000000000..05f1fa9fd8
--- /dev/null
+++ b/meta/recipes-connectivity/dhcp/dhcp/CVE-2015-8605.patch
@@ -0,0 +1,101 @@
+Solves CVE-2015-8605 that caused DoS when an invalid length field in IPv4 UDP
+was received by the server.
+
+Upstream-Status: Backport (v4.3.3p1)
+CVE: CVE-2015-8605
+
+From: https://source.isc.org/cgi-bin/gitweb.cgi?p=dhcp.git;a=commit;h=4ce21cb6301d665de01c1a6209e40f5f35072c0c
+
+Signed-off-by: Mariano Lopez <mariano.lopez@linux.intel.com>
+
+=======================================================================
+diff --git a/common/packet.c b/common/packet.c
+index b530432..e600e37 100644
+--- a/common/packet.c
++++ b/common/packet.c
+@@ -220,7 +220,28 @@ ssize_t decode_hw_header (interface, buf, bufix, from)
+        }
+ }
+ 
+-/* UDP header and IP header decoded together for convenience. */
++/*!
++ *
++ * \brief UDP header and IP header decoded together for convenience.
++ *
++ * Attempt to decode the UDP and IP headers and, if necessary, checksum
++ * the packet.
++ *
++ * \param inteface - the interface on which the packet was recevied
++ * \param buf - a pointer to the buffer for the received packet
++ * \param bufix - where to start processing the buffer, previous
++ *                routines may have processed parts of the buffer already
++ * \param from - space to return the address of the packet sender
++ * \param buflen - remaining length of the buffer, this will have been
++ *                 decremented by bufix by the caller
++ * \param rbuflen - space to return the length of the payload from the udp
++ *                  header
++ * \param csum_ready - indication if the checksum is valid for use
++ *                     non-zero indicates the checksum should be validated
++ *
++ * \return - the index to the first byte of the udp payload (that is the
++ *           start of the DHCP packet
++ */
+ 
+ ssize_t
+ decode_udp_ip_header(struct interface_info *interface,
+@@ -231,7 +252,7 @@ decode_udp_ip_header(struct interface_info *interface,
+   unsigned char *data;
+   struct ip ip;
+   struct udphdr udp;
+-  unsigned char *upp, *endbuf;
++  unsigned char *upp;
+   u_int32_t ip_len, ulen, pkt_len;
+   static unsigned int ip_packets_seen = 0;
+   static unsigned int ip_packets_bad_checksum = 0;
+@@ -241,11 +262,8 @@ decode_udp_ip_header(struct interface_info *interface,
+   static unsigned int udp_packets_length_overflow = 0;
+   unsigned len;
+ 
+-  /* Designate the end of the input buffer for bounds checks. */
+-  endbuf = buf + bufix + buflen;
+-
+   /* Assure there is at least an IP header there. */
+-  if ((buf + bufix + sizeof(ip)) > endbuf)
++  if (sizeof(ip) > buflen)
+          return -1;
+ 
+   /* Copy the IP header into a stack aligned structure for inspection.
+@@ -257,13 +275,17 @@ decode_udp_ip_header(struct interface_info *interface,
+   ip_len = (*upp & 0x0f) << 2;
+   upp += ip_len;
+ 
+-  /* Check the IP packet length. */
++  /* Check packet lengths are within the buffer:
++   * first the ip header (ip_len)
++   * then the packet length from the ip header (pkt_len)
++   * then the udp header (ip_len + sizeof(udp)
++   * We are liberal in what we accept, the udp payload should fit within
++   * pkt_len, but we only check against the full buffer size.
++   */
+   pkt_len = ntohs(ip.ip_len);
+-  if (pkt_len > buflen)
+-       return -1;
+-
+-  /* Assure after ip_len bytes that there is enough room for a UDP header. */
+-  if ((upp + sizeof(udp)) > endbuf)
++  if ((ip_len > buflen) ||
++      (pkt_len > buflen) ||
++      ((ip_len + sizeof(udp)) > buflen))
+          return -1;
+ 
+   /* Copy the UDP header into a stack aligned structure for inspection. */
+@@ -284,7 +306,8 @@ decode_udp_ip_header(struct interface_info *interface,
+        return -1;
+ 
+   udp_packets_length_checked++;
+-  if ((upp + ulen) > endbuf) {
++  /* verify that the payload length from the udp packet fits in the buffer */
++  if ((ip_len + ulen) > buflen) {
+        udp_packets_length_overflow++;
+        if (((udp_packets_length_checked > 4) &&
+             (udp_packets_length_overflow != 0)) &&
diff --git a/meta/recipes-connectivity/dhcp/dhcp/CVE-2015-8605_1.patch b/meta/recipes-connectivity/dhcp/dhcp/CVE-2015-8605_1.patch
new file mode 100644
index 0000000000..aa93c5e123
--- /dev/null
+++ b/meta/recipes-connectivity/dhcp/dhcp/CVE-2015-8605_1.patch
@@ -0,0 +1,131 @@
+This patch is needed in order to apply the patch for CVE-2015-8605.
+
+Upstream-Status: Backport (4.3.2+)
+
+From: https://source.isc.org/cgi-bin/gitweb.cgi?p=dhcp.git;a=commit;h=0ce1aa94454ce9b50d592c08d7e0c559d38d3bc5
+
+Signed-off-by: Mariano Lopez <mariano.lopez@linux.intel.com>
+---
+From 0ce1aa94454ce9b50d592c08d7e0c559d38d3bc5 Mon Sep 17 00:00:00 2001
+From: Thomas Markwalder <tmark@isc.org>
+Date: Mon, 8 Sep 2014 09:31:32 -0400
+Subject: [PATCH] [master] Corrected error in UDP bad packet logging
+
+    Merges in rt36897
+---
+ common/packet.c | 55 +++++++++++++++++++++++++++++++++++--------------------
+ 1 file changed, 35 insertions(+), 20 deletions(-)
+
+diff --git a/common/packet.c b/common/packet.c
+index 45e96e8..7460f3d 100644
+--- a/common/packet.c
++++ b/common/packet.c
+@@ -3,7 +3,7 @@
+    Packet assembly code, originally contributed by Archie Cobbs. */
+ 
+ /*
+- * Copyright (c) 2009,2012 by Internet Systems Consortium, Inc. ("ISC")
++ * Copyright (c) 2009,2012,2014 by Internet Systems Consortium, Inc. ("ISC")
+  * Copyright (c) 2004,2005,2007 by Internet Systems Consortium, Inc. ("ISC")
+  * Copyright (c) 1996-2003 by Internet Software Consortium
+  *
+@@ -234,12 +234,12 @@ decode_udp_ip_header(struct interface_info *interface,
+   unsigned char *upp, *endbuf;
+   u_int32_t ip_len, ulen, pkt_len;
+   u_int32_t sum, usum;
+-  static int ip_packets_seen;
+-  static int ip_packets_bad_checksum;
+-  static int udp_packets_seen;
+-  static int udp_packets_bad_checksum;
+-  static int udp_packets_length_checked;
+-  static int udp_packets_length_overflow;
++  static unsigned int ip_packets_seen = 0;
++  static unsigned int ip_packets_bad_checksum = 0;
++  static unsigned int udp_packets_seen = 0;
++  static unsigned int udp_packets_bad_checksum = 0;
++  static unsigned int udp_packets_length_checked = 0;
++  static unsigned int udp_packets_length_overflow = 0;
+   unsigned len;
+ 
+   /* Designate the end of the input buffer for bounds checks. */
+@@ -287,10 +287,10 @@ decode_udp_ip_header(struct interface_info *interface,
+   udp_packets_length_checked++;
+   if ((upp + ulen) > endbuf) {
+        udp_packets_length_overflow++;
+-       if ((udp_packets_length_checked > 4) &&
+-           ((udp_packets_length_checked /
+-             udp_packets_length_overflow) < 2)) {
+-               log_info("%d udp packets in %d too long - dropped",
++       if (((udp_packets_length_checked > 4) &&
++            (udp_packets_length_overflow != 0)) &&
++           ((udp_packets_length_checked / udp_packets_length_overflow) < 2)) {
++               log_info("%u udp packets in %u too long - dropped",
+                         udp_packets_length_overflow,
+                         udp_packets_length_checked);
+                udp_packets_length_overflow = 0;
+@@ -299,22 +299,31 @@ decode_udp_ip_header(struct interface_info *interface,
+        return -1;
+   }
+ 
+-  if ((ulen < sizeof(udp)) || ((upp + ulen) > endbuf))
+-       return -1;
++  /* If at least 5 with less than 50% bad, start over */
++  if (udp_packets_length_checked > 4) {
++       udp_packets_length_overflow = 0;
++       udp_packets_length_checked = 0;
++  }
+ 
+   /* Check the IP header checksum - it should be zero. */
+-  ++ip_packets_seen;
++  ip_packets_seen++;
+   if (wrapsum (checksum (buf + bufix, ip_len, 0))) {
+          ++ip_packets_bad_checksum;
+-         if (ip_packets_seen > 4 &&
+-             (ip_packets_seen / ip_packets_bad_checksum) < 2) {
+-                 log_info ("%d bad IP checksums seen in %d packets",
++         if (((ip_packets_seen > 4) && (ip_packets_bad_checksum != 0)) &&
++             ((ip_packets_seen / ip_packets_bad_checksum) < 2)) {
++                 log_info ("%u bad IP checksums seen in %u packets",
+                            ip_packets_bad_checksum, ip_packets_seen);
+                  ip_packets_seen = ip_packets_bad_checksum = 0;
+          }
+          return -1;
+   }
+ 
++  /* If at least 5 with less than 50% bad, start over */
++  if (ip_packets_seen > 4) {
++       ip_packets_bad_checksum = 0;
++       ip_packets_seen = 0;
++  }
++
+   /* Copy out the IP source address... */
+   memcpy(&from->sin_addr, &ip.ip_src, 4);
+ 
+@@ -339,15 +348,21 @@ decode_udp_ip_header(struct interface_info *interface,
+   udp_packets_seen++;
+   if (usum && usum != sum) {
+          udp_packets_bad_checksum++;
+-         if (udp_packets_seen > 4 &&
+-             (udp_packets_seen / udp_packets_bad_checksum) < 2) {
+-                 log_info ("%d bad udp checksums in %d packets",
++         if (((udp_packets_seen > 4) && (udp_packets_bad_checksum != 0)) &&
++             ((udp_packets_seen / udp_packets_bad_checksum) < 2)) {
++                 log_info ("%u bad udp checksums in %u packets",
+                            udp_packets_bad_checksum, udp_packets_seen);
+                  udp_packets_seen = udp_packets_bad_checksum = 0;
+          }
+          return -1;
+   }
+ 
++  /* If at least 5 with less than 50% bad, start over */
++  if (udp_packets_seen > 4) {
++       udp_packets_bad_checksum = 0;
++       udp_packets_seen = 0;
++  }
++
+   /* Copy out the port... */
+   memcpy (&from -> sin_port, &udp.uh_sport, sizeof udp.uh_sport);
+ 
+-- 
+2.6.2
+
diff --git a/meta/recipes-connectivity/dhcp/dhcp_4.3.1.bb b/meta/recipes-connectivity/dhcp/dhcp_4.3.1.bb
index d4414cc347..46166932f9 100644
--- a/meta/recipes-connectivity/dhcp/dhcp_4.3.1.bb
+++ b/meta/recipes-connectivity/dhcp/dhcp_4.3.1.bb
@@ -6,7 +6,9 @@ SRC_URI += "file://dhcp-3.0.3-dhclient-dbus.patch;striplevel=0 \
             file://fixsepbuild.patch \
             file://dhclient-script-drop-resolv.conf.dhclient.patch \
             file://replace-ifconfig-route.patch \
+            file://CVE-2015-8605_1.patch \
             file://dhcp-xen-checksum.patch \
+            file://CVE-2015-8605.patch \
            "
 
 SRC_URI[md5sum] = "b3a42ece3c7f2cd2e74a3e12ca881d20"