diff options
| -rw-r--r-- | pkg/sentry/socket/netfilter/netfilter.go | 46 | ||||
| -rw-r--r-- | pkg/tcpip/iptables/iptables.go | 9 | ||||
| -rw-r--r-- | pkg/tcpip/iptables/types.go | 13 | ||||
| -rw-r--r-- | pkg/tcpip/network/ipv4/ipv4.go | 3 |
4 files changed, 62 insertions, 9 deletions
diff --git a/pkg/sentry/socket/netfilter/netfilter.go b/pkg/sentry/socket/netfilter/netfilter.go index 507a77483..c65c36081 100644 --- a/pkg/sentry/socket/netfilter/netfilter.go +++ b/pkg/sentry/socket/netfilter/netfilter.go @@ -25,6 +25,7 @@ import ( "gvisor.dev/gvisor/pkg/sentry/kernel" "gvisor.dev/gvisor/pkg/sentry/usermem" "gvisor.dev/gvisor/pkg/syserr" + "gvisor.dev/gvisor/pkg/tcpip" "gvisor.dev/gvisor/pkg/tcpip/iptables" "gvisor.dev/gvisor/pkg/tcpip/stack" ) @@ -163,6 +164,9 @@ func convertNetstackToBinary(tablename string, table iptables.Table) (linux.Kern // Each rule corresponds to an entry. entry := linux.KernelIPTEntry{ IPTEntry: linux.IPTEntry{ + IP: linux.IPTIP{ + Protocol: uint16(rule.Filter.Protocol), + }, NextOffset: linux.SizeOfIPTEntry, TargetOffset: linux.SizeOfIPTEntry, }, @@ -321,12 +325,11 @@ func SetEntries(stack *stack.Stack, optVal []byte) *syserr.Error { return syserr.ErrInvalidArgument } - // TODO(gvisor.dev/issue/170): We should support IPTIP - // filtering. We reject any nonzero IPTIP values for now. - emptyIPTIP := linux.IPTIP{} - if entry.IP != emptyIPTIP { - log.Warningf("netfilter: non-empty struct iptip found") - return syserr.ErrInvalidArgument + // TODO(gvisor.dev/issue/170): We should support more IPTIP + // filtering fields. + filter, err := filterFromIPTIP(entry.IP) + if err != nil { + return err } // Get the target of the rule. @@ -336,7 +339,10 @@ func SetEntries(stack *stack.Stack, optVal []byte) *syserr.Error { } optVal = optVal[consumed:] - table.Rules = append(table.Rules, iptables.Rule{Target: target}) + table.Rules = append(table.Rules, iptables.Rule{ + Filter: filter, + Target: target, + }) offsets = append(offsets, offset) offset += linux.SizeOfIPTEntry + consumed } @@ -460,6 +466,32 @@ func parseTarget(optVal []byte) (iptables.Target, uint32, *syserr.Error) { return nil, 0, syserr.ErrInvalidArgument } +func filterFromIPTIP(iptip linux.IPTIP) (iptables.IPHeaderFilter, *syserr.Error) { + if containsUnsupportedFields(iptip) { + log.Warningf("netfilter: unsupported fields in struct iptip: %+v", iptip) + return iptables.IPHeaderFilter{}, syserr.ErrInvalidArgument + } + return iptables.IPHeaderFilter{ + Protocol: tcpip.TransportProtocolNumber(iptip.Protocol), + }, nil +} + +func containsUnsupportedFields(iptip linux.IPTIP) bool { + // Currently we check that everything except protocol is zeroed. + var emptyInetAddr = linux.InetAddr{} + var emptyInterface = [linux.IFNAMSIZ]byte{} + return iptip.Dst != emptyInetAddr || + iptip.Src != emptyInetAddr || + iptip.SrcMask != emptyInetAddr || + iptip.DstMask != emptyInetAddr || + iptip.InputInterface != emptyInterface || + iptip.OutputInterface != emptyInterface || + iptip.InputInterfaceMask != emptyInterface || + iptip.OutputInterfaceMask != emptyInterface || + iptip.Flags != 0 || + iptip.InverseFlags != 0 +} + func hookFromLinux(hook int) iptables.Hook { switch hook { case linux.NF_INET_PRE_ROUTING: diff --git a/pkg/tcpip/iptables/iptables.go b/pkg/tcpip/iptables/iptables.go index 605a71679..fc06b5b87 100644 --- a/pkg/tcpip/iptables/iptables.go +++ b/pkg/tcpip/iptables/iptables.go @@ -20,6 +20,7 @@ import ( "fmt" "gvisor.dev/gvisor/pkg/tcpip" + "gvisor.dev/gvisor/pkg/tcpip/header" ) // Table names. @@ -184,8 +185,16 @@ func (it *IPTables) checkTable(hook Hook, pkt tcpip.PacketBuffer, tablename stri panic(fmt.Sprintf("Traversed past the entire list of iptables rules in table %q.", tablename)) } +// Precondition: pk.NetworkHeader is set. func (it *IPTables) checkRule(hook Hook, pkt tcpip.PacketBuffer, table Table, ruleIdx int) Verdict { rule := table.Rules[ruleIdx] + + // First check whether the packet matches the IP header filter. + // TODO(gvisor.dev/issue/170): Support other fields of the filter. + if rule.Filter.Protocol != 0 && rule.Filter.Protocol != header.IPv4(pkt.NetworkHeader).TransportProtocol() { + return Continue + } + // Go through each rule matcher. If they all match, run // the rule target. for _, matcher := range rule.Matchers { diff --git a/pkg/tcpip/iptables/types.go b/pkg/tcpip/iptables/types.go index 9f6906100..a8b972f1b 100644 --- a/pkg/tcpip/iptables/types.go +++ b/pkg/tcpip/iptables/types.go @@ -14,7 +14,9 @@ package iptables -import "gvisor.dev/gvisor/pkg/tcpip" +import ( + "gvisor.dev/gvisor/pkg/tcpip" +) // A Hook specifies one of the hooks built into the network stack. // @@ -151,6 +153,9 @@ func (table *Table) SetMetadata(metadata interface{}) { // packets this rule applies to. If there are no matchers in the rule, it // applies to any packet. type Rule struct { + // Filter holds basic IP filtering fields common to every rule. + Filter IPHeaderFilter + // Matchers is the list of matchers for this rule. Matchers []Matcher @@ -158,6 +163,12 @@ type Rule struct { Target Target } +// IPHeaderFilter holds basic IP filtering data common to every rule. +type IPHeaderFilter struct { + // Protocol matches the transport protocol. + Protocol tcpip.TransportProtocolNumber +} + // A Matcher is the interface for matching packets. type Matcher interface { // Match returns whether the packet matches and whether the packet diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go index 0a1453b31..85512f9b2 100644 --- a/pkg/tcpip/network/ipv4/ipv4.go +++ b/pkg/tcpip/network/ipv4/ipv4.go @@ -353,7 +353,8 @@ func (e *endpoint) HandlePacket(r *stack.Route, pkt tcpip.PacketBuffer) { } pkt.NetworkHeader = headerView[:h.HeaderLength()] - // iptables filtering. + // iptables filtering. All packets that reach here are intended for + // this machine and will not be forwarded. ipt := e.stack.IPTables() if ok := ipt.Check(iptables.Input, pkt); !ok { // iptables is telling us to drop the packet. |