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path: root/pkg/tcpip/stack/conntrack.go
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2020-07-22iptables: don't NAT existing connectionsKevin Krakauer
Fixes a NAT bug that manifested as: - A SYN was sent from gVisor to another host, unaffected by iptables. - The corresponding SYN/ACK was NATted by a PREROUTING REDIRECT rule despite being part of the existing connection. - The socket that sent the SYN never received the SYN/ACK and thus a connection could not be established. We handle this (as Linux does) by tracking all connections, inserting a no-op conntrack rule for new connections with no rules of their own. Needed for istio support (#170).
2020-07-13garbage collect connectionsKevin Krakauer
As in Linux, we must periodically clean up unused connections. PiperOrigin-RevId: 321003353
2020-06-25conntrack refactor, no behavior changesKevin Krakauer
- Split connTrackForPacket into 2 functions instead of switching on flag - Replace hash with struct keys. - Remove prefixes where possible - Remove unused connStatus, timeout - Flatten ConnTrack struct a bit - some intermediate structs had no meaning outside of the context of their parent. - Protect conn.tcb with a mutex - Remove redundant error checking (e.g. when is pkt.NetworkHeader valid) - Clarify that HandlePacket and CreateConnFor are the expected entrypoints for ConnTrack PiperOrigin-RevId: 318407168
2020-06-07netstack: parse incoming packet headers up-frontKevin Krakauer
Netstack has traditionally parsed headers on-demand as a packet moves up the stack. This is conceptually simple and convenient, but incompatible with iptables, where headers can be inspected and mangled before even a routing decision is made. This changes header parsing to happen early in the incoming packet path, as soon as the NIC gets the packet from a link endpoint. Even if an invalid packet is found (e.g. a TCP header of insufficient length), the packet is passed up the stack for proper stats bookkeeping. PiperOrigin-RevId: 315179302
2020-06-03Pass PacketBuffer as pointer.Ting-Yu Wang
Historically we've been passing PacketBuffer by shallow copying through out the stack. Right now, this is only correct as the caller would not use PacketBuffer after passing into the next layer in netstack. With new buffer management effort in gVisor/netstack, PacketBuffer will own a Buffer (to be added). Internally, both PacketBuffer and Buffer may have pointers and shallow copying shouldn't be used. Updates #2404. PiperOrigin-RevId: 314610879
2020-05-01Support for connection tracking of TCP packets.Nayana Bidari
Connection tracking is used to track packets in prerouting and output hooks of iptables. The NAT rules modify the tuples in connections. The connection tracking code modifies the packets by looking at the modified tuples.