diff options
| -rw-r--r-- | pkg/sentry/socket/netfilter/netfilter.go | 4 | ||||
| -rw-r--r-- | pkg/tcpip/iptables/BUILD | 4 | ||||
| -rw-r--r-- | pkg/tcpip/iptables/iptables.go | 59 | ||||
| -rw-r--r-- | pkg/tcpip/network/ipv4/ipv4.go | 6 | ||||
| -rw-r--r-- | test/iptables/filter_input.go | 2 |
5 files changed, 73 insertions, 2 deletions
diff --git a/pkg/sentry/socket/netfilter/netfilter.go b/pkg/sentry/socket/netfilter/netfilter.go index e4c493141..57785220e 100644 --- a/pkg/sentry/socket/netfilter/netfilter.go +++ b/pkg/sentry/socket/netfilter/netfilter.go @@ -368,6 +368,10 @@ func SetEntries(stack *stack.Stack, optVal []byte) *syserr.Error { } } + // TODO(gvisor.dev/issue/170): Check the following conditions: + // - There are no loops. + // - There are no chains without an unconditional final rule. + ipt := stack.IPTables() table.SetMetadata(metadata{ HookEntry: replace.HookEntry, diff --git a/pkg/tcpip/iptables/BUILD b/pkg/tcpip/iptables/BUILD index cc5f531e2..6ed7c6da0 100644 --- a/pkg/tcpip/iptables/BUILD +++ b/pkg/tcpip/iptables/BUILD @@ -11,5 +11,7 @@ go_library( ], importpath = "gvisor.dev/gvisor/pkg/tcpip/iptables", visibility = ["//visibility:public"], - deps = ["//pkg/tcpip/buffer"], + deps = [ + "//pkg/tcpip", + ], ) diff --git a/pkg/tcpip/iptables/iptables.go b/pkg/tcpip/iptables/iptables.go index 9e7005374..025a4679d 100644 --- a/pkg/tcpip/iptables/iptables.go +++ b/pkg/tcpip/iptables/iptables.go @@ -16,6 +16,8 @@ // tool. package iptables +import "github.com/google/netstack/tcpip" + const ( TablenameNat = "nat" TablenameMangle = "mangle" @@ -121,3 +123,60 @@ func EmptyFilterTable() Table { UserChains: map[string]int{}, } } + +// Check runs pkt through the rules for hook. It returns true when the packet +// should continue traversing the network stack and false when it should be +// dropped. +func (it *IPTables) Check(hook Hook, pkt tcpip.PacketBuffer) bool { + // TODO(gvisor.dev/issue/170): A lot of this is uncomplicated because + // we're missing features. Jumps, the call stack, etc. aren't checked + // for yet because we're yet to support them. + log.Infof("kevin: iptables.IPTables: checking hook %v", hook) + + // Go through each table containing the hook. + for _, tablename := range it.Priorities[hook] { + verdict := it.checkTable(tablename) + switch verdict { + // TODO: We either got a final verdict or simply continue on. + } + } +} + +func (it *IPTables) checkTable(hook Hook, pkt tcpip.PacketBuffer, tablename string) bool { + log.Infof("kevin: iptables.IPTables: checking table %q", tablename) + table := it.Tables[tablename] + ruleIdx := table.BuiltinChains[hook] + + // Start from ruleIdx and go down until a rule gives us a verdict. + for ruleIdx := table.BuiltinChains[hook]; ruleIdx < len(table.Rules); ruleIdx++ { + verdict := checkRule(hook, pkt, table, ruleIdx) + switch verdict { + case Accept, Drop: + return verdict + case Continue: + continue + case Stolen, Queue, Repeat, None, Jump, Return: + } + } + + panic("Traversed past the entire list of iptables rules.") +} + +func (it *IPTables) checkRule(hook Hook, pkt tcpip.PacketBuffer, table Table, ruleIdx int) Verdict { + rule := table.Rules[ruleIdx] + // Go through each rule matcher. If they all match, run + // the rule target. + for _, matcher := range rule.Matchers { + matches, hotdrop := matcher.Match(hook, pkt, "") + if hotdrop { + return Drop + } + if !matches { + return Continue + } + } + + // All the matchers matched, so run the target. + verdict, _ := rule.Target.Action(pkt) + return verdict +} diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go index e645cf62c..bbb5aafee 100644 --- a/pkg/tcpip/network/ipv4/ipv4.go +++ b/pkg/tcpip/network/ipv4/ipv4.go @@ -350,6 +350,12 @@ func (e *endpoint) HandlePacket(r *stack.Route, pkt tcpip.PacketBuffer) { } pkt.NetworkHeader = headerView[:h.HeaderLength()] + // iptables filtering. + if ok := iptables.Check(iptables.Input, pkt); !ok { + // iptables is telling us to drop the packet. + return + } + hlen := int(h.HeaderLength()) tlen := int(h.TotalLength()) pkt.Data.TrimFront(hlen) diff --git a/test/iptables/filter_input.go b/test/iptables/filter_input.go index 1723a4d3e..7c4d469fa 100644 --- a/test/iptables/filter_input.go +++ b/test/iptables/filter_input.go @@ -138,7 +138,7 @@ func (FilterInputDropAll) ContainerAction(ip net.IP) error { return err } - // Listen for All packets on dropPort. + // Listen for all packets on dropPort. if err := listenUDP(dropPort, sendloopDuration); err == nil { return fmt.Errorf("packets should have been dropped, but got a packet") } else if netErr, ok := err.(net.Error); !ok || !netErr.Timeout() { |