This changes the decapsulation logic for GRE/ERSPAN payloads to re-use
existing Layer 2 parsing logic that already handles things like 802.1Q
tags correctly before going on to process the inner IPv4/IPv6 payload.
* Better parsing/error-checking of VXLAN and encapsulated packet headers
* Add/implement the "vxlan_packet" event
* Add "Tunnel::vxlan_ports" option to tune the set of VXLAN ports to
analyze/decapsulate
* Add "Tunnel::validate_vxlan_checksums" option to allow for tuning of how
checksums associated with the outer UDP header of a possible VXLAN
tunnel are handled
Fixes GH-250
IP packets that have a header length that is greater than the total
length of the packet cause a integer overflow, which cause range-checks
to fail, which causes OOB reads.
Furthermore Bro does not currently check the version field of IP packets
that are read from tunnels. I added this check - otherwhise Bro reports
bogus IP information in its error messages, just converting the data
from the place where the IP information is supposed to be to IPs.
This behavior brings us closer to what other software (e.g. Wireshark)
displays in these cases.
This includes enhanced GRE headers. GRE tunnels are treated just like
IP-in-IP tunnels by parsing past the GRE header in between the delivery
and payload IP packets.
Added a generic gtpv1_message event generated for any GTP message type.
Added specific events for the create/update/delete PDP context
request/response messages.
Addresses #934.
This currently supports automatic decapsulation of GTP-U packets on
UDP port 2152.
The GTPv1 headers for such tunnels can be inspected by handling the
"gtpv1_g_pdu_packet" event, which has a parameter of type "gtpv1_hdr".
Analyzer and test cases are derived from submissions by Carsten Langer.
Addresses #690.
Teredo bubble packets (IPv6 w/ No Next Header and zero Payload Length)
with data extending past the inner IPv6 header (the outer IPv4 header's
Total Length and UDP header's Length indicate this) now only raises
a "Teredo_payload_len_mismatch" weird instead of causing a
ProtocolViolation().
This also fixes a crash in NetSessions::ParseIPPacket() that occurred
when the packet length didn't match the payload length field.
The Tunnel::yielding_teredo_decapsulation (on by default) makes it so
the Teredo analyzer doesn't attempt to decapsulate payloads when
there's already a sibling analyzer that thinks it's parsing the right
protocol. Sometimes, UDP payloads just happen to look like they are
validly Teredo-encapsulated and doing further analysis on the
decapsulated packet can quickly turn into a weird; this change helps
reduce such weirds.
These are called "teredo_packet", "teredo_authentication",
"teredo_origin_indication", and "teredo_bubble" and may be raised
on a per-packet basis depending on Teredo encapsulation method.
UDP tunnel support removed for now, to be re-added in specific
analyzers later, but IP-in-IP is now decapsulated recursively
so nested tunnels can be seen and the inner packets get sent
through the IP fragment reassembler if necessary.
