This is a fourth draft of the first steps in implementing more general
"connection" tracking, as described at:
https://pad.passt.top/p/NewForwardingModel
This series changes the TCP connection table and hash table into a
more general flow table that can track other protocols as well. Each
flow uniformly keeps track of all the relevant addresses and ports,
which will allow for more robust control of NAT and port forwarding.
ICMP is converted to use the new flow table.
This doesn't include UDP, but I'm working on it right now and making
progress. I'm posting this to give a head start on the review :)
Caveats:
* We significantly increase the size of a connection/flow entry
- Can probably be mitigated, but I haven't investigated much yet
* We perform a number of extra getsockname() calls to know some of
the socket endpoints
- Haven't yet measured how much performance impact that has
- Can be mitigated in at least some cases, but again, haven't
tried yet
Changes since v4:
* Complex rebase on top of the many things that have happened
upstream since v3.
* Assorted other changes.
Changes since v3:
* Replace TAPFSIDE() and SOCKFSIDE() macros with local variables.
Changes since v2:
* Cosmetic fixes based on review
* Extra doc comments for enum flow_type
* Rename flowside to flowaddrs which turns out to make more sense in
light of future changes
* Fix bug where the socket flowaddrs for tap initiated connections
wasn't initialised to match the socket address we were using in the
case of map-gw NAT
* New flowaddrs_from_sock() helper used in most cases which is cleaner
and should avoid bugs like the above
* Using newer centralised workarounds for clang-tidy issue 58992
* Remove duplicate definition of FLOW_MAX as maximum flow type and
maximum number of tracked flows
* Rebased on newer versions of preliminary work (ICMP, flow based
dispatch and allocation, bind/address cleanups)
* Unified hash table as well as base flow table
* Integrated ICMP
Changes since v1:
* Terminology changes
- "Endpoint" address/port instead of "correspondent" address/port
- "flowside" instead of "demiflow"
* Actually move the connection table to a new flow table structure in
new files
* Significant rearrangement of earlier patchs on top of that new
table, to reduce churn
David Gibson (16):
flow: Common data structures for tracking flow addresses
tcp: Maintain flowside information for "tap" connections
tcp_splice: Maintain flowside information for spliced connections
tcp: Obtain guest address from flowside
tcp: Simplify endpoint validation using flowside information
tcp, tcp_splice: Construct sockaddrs for connect() from flowside
tcp_splice: Eliminate SPLICE_V6 flag
tcp, flow: Replace TCP specific hash function with general flow hash
flow, tcp: Generalise TCP hash table to general flow hash table
tcp: Re-use flow hash for initial sequence number generation
icmp: Populate flowside information
icmp: Use flowsides as the source of truth wherever possible
icmp: Look up ping flows using flow hash
icmp: Eliminate icmp_id_map
flow, tcp: flow based NAT and port forwarding for TCP
flow, icmp: Use general flow forwarding rules for ICMP
flow.c | 199 ++++++++++++++++++++-
flow.h | 97 +++++++++++
fwd.c | 139 +++++++++++++++
fwd.h | 5 +
icmp.c | 83 +++++----
icmp_flow.h | 1 -
inany.h | 29 +++-
passt.h | 3 +
pif.h | 1 -
tap.c | 11 --
tap.h | 1 -
tcp.c | 475 +++++++++++++--------------------------------------
tcp_conn.h | 20 +--
tcp_splice.c | 93 ++--------
tcp_splice.h | 5 +-
15 files changed, 649 insertions(+), 513 deletions(-)
--
2.44.0