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Fix panic in sniffer.

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Packets written via SOCK_RAW are guaranteed to have network headers, but not
transport headers. Check first whether there are enough bytes left in the packet
to contain a transport header before attempting to parse it.

PiperOrigin-RevId: 282363895
This commit is contained in:
Kevin Krakauer
2019-11-25 09:11:05 -08:00
committed by gVisor bot
parent c3b93afeaf
commit 2b1b51f1d7
1 changed files with 14 additions and 0 deletions
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pkg/tcpip/link/sniffer/sniffer.go
+14
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@@ -49,6 +49,13 @@ var LogPackets uint32 = 1
// LogPacketsToFile must be accessed atomically.
var LogPacketsToFile uint32 = 1
var transportProtocolMinSizes map[tcpip.TransportProtocolNumber]int = map[tcpip.TransportProtocolNumber]int{
header.ICMPv4ProtocolNumber: header.IPv4MinimumSize,
header.ICMPv6ProtocolNumber: header.IPv6MinimumSize,
header.UDPProtocolNumber: header.UDPMinimumSize,
header.TCPProtocolNumber: header.TCPMinimumSize,
}
type endpoint struct {
dispatcher stack.NetworkDispatcher
lower stack.LinkEndpoint
@@ -333,6 +340,13 @@ func logPacket(prefix string, protocol tcpip.NetworkProtocolNumber, b buffer.Vie
return
}
// We aren't guaranteed to have a transport header - it's possible for
// writes via raw endpoints to contain only network headers.
if minSize, ok := transportProtocolMinSizes[tcpip.TransportProtocolNumber(transProto)]; ok && len(b) < minSize {
log.Infof("%s %v -> %v transport protocol: %d, but no transport header found (possible raw packet)", prefix, src, dst, transProto)
return
}
// Figure out the transport layer info.
transName := "unknown"
srcPort := uint16(0)