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Sanity check ICMP6 router advertisement packets

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There is a chance a packet can slip by before we install the filter
on our socket listening for RAs, so add some basic sanity checking
to make sure we've recieved an RA.

Change-Id: I14cf84a0814896a41e00f50af376dfc4988d36cb
Fixes: 29586253
This commit is contained in:
Paul Jensen
2016-07-20 15:01:17 -04:00
committed by Erik Kline
parent 8eaa65b867
commit a36213867a
1 changed files with 15 additions and 1 deletions
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16
services/net/java/android/net/apf/ApfFilter.java
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@@ -131,6 +131,7 @@ public class ApfFilter {
private static final int ICMP6_TYPE_OFFSET = ETH_HEADER_LEN + IPV6_HEADER_LEN;
private static final int ICMP6_NEIGHBOR_ANNOUNCEMENT = 136;
private static final int ICMP6_ROUTER_ADVERTISEMENT = 134;
// NOTE: this must be added to the IPv4 header length in IPV4_HEADER_SIZE_MEMORY_SLOT
private static final int UDP_DESTINATION_PORT_OFFSET = ETH_HEADER_LEN + 2;
@@ -306,7 +307,11 @@ public class ApfFilter {
}
private long uint32(int s) {
return s & 0xffffffff;
return s & 0xffffffffL;
}
private long getUint16(ByteBuffer buffer, int position) {
return uint16(buffer.getShort(position));
}
private void prefixOptionToString(StringBuffer sb, int offset) {
@@ -375,6 +380,15 @@ public class ApfFilter {
mPacket.clear();
mLastSeen = curTime();
// Sanity check packet in case a packet arrives before we attach RA filter
// to our packet socket. b/29586253
if (getUint16(mPacket, ETH_ETHERTYPE_OFFSET) != ETH_P_IPV6 ||
uint8(mPacket.get(IPV6_NEXT_HEADER_OFFSET)) != IPPROTO_ICMPV6 ||
uint8(mPacket.get(ICMP6_TYPE_OFFSET)) != ICMP6_ROUTER_ADVERTISEMENT) {
throw new IllegalArgumentException("Not an ICMP6 router advertisement");
}
// Ignore the checksum.
int lastNonLifetimeStart = addNonLifetime(0,
ICMP6_RA_CHECKSUM_OFFSET,