diff options
Diffstat (limited to 'pkg/sentry/socket')
| -rw-r--r-- | pkg/sentry/socket/netfilter/netfilter.go | 25 |
1 files changed, 12 insertions, 13 deletions
diff --git a/pkg/sentry/socket/netfilter/netfilter.go b/pkg/sentry/socket/netfilter/netfilter.go index b8848f08a..a06562743 100644 --- a/pkg/sentry/socket/netfilter/netfilter.go +++ b/pkg/sentry/socket/netfilter/netfilter.go @@ -43,7 +43,7 @@ const ( // a metadata struct when the tables are written, and when they are read out we // verify that certain fields are the same. // -// metadata is opaque to netstack. +// metadata is used by this serialization/deserializing code, not netstack. type metadata struct { HookEntry [linux.NF_INET_NUMHOOKS]uint32 Underflow [linux.NF_INET_NUMHOOKS]uint32 @@ -51,14 +51,10 @@ type metadata struct { Size uint32 } -const enableDebug = false - // nflog logs messages related to the writing and reading of iptables, but only // when enableDebug is true. func nflog(format string, args ...interface{}) { - if enableDebug { - log.Infof("netfilter: "+format, args...) - } + log.Infof("netfilter: "+format, args...) } // GetInfo returns information about iptables. @@ -233,14 +229,12 @@ func convertNetstackToBinary(tablename string, table iptables.Table) (linux.Kern return entries, meta, nil } -// TODO: SOMEHOW THIS IS NOT GETTING APPENDED! func marshalMatcher(matcher iptables.Matcher) []byte { switch m := matcher.(type) { case *iptables.UDPMatcher: return marshalUDPMatcher(m) default: - // TODO(gvisor.dev/issue/170): We don't support any matchers - // yet, so any call to marshalMatcher will panic. + // TODO(gvisor.dev/issue/170): Support other matchers. panic(fmt.Errorf("unknown matcher of type %T", matcher)) } } @@ -249,11 +243,11 @@ func marshalUDPMatcher(matcher *iptables.UDPMatcher) []byte { nflog("convert to binary: marshalling UDP matcher: %+v", matcher) // We have to pad this struct size to a multiple of 8 bytes. - const size = linux.SizeOfXTEntryMatch + linux.SizeOfXTUDP + 6 + size := alignUp(linux.SizeOfXTEntryMatch+linux.SizeOfXTUDP, 8) linuxMatcher := linux.KernelXTEntryMatch{ XTEntryMatch: linux.XTEntryMatch{ - MatchSize: size, + MatchSize: uint16(size), }, Data: make([]byte, 0, linux.SizeOfXTUDP), } @@ -270,7 +264,7 @@ func marshalUDPMatcher(matcher *iptables.UDPMatcher) []byte { buf := make([]byte, 0, size) buf = binary.Marshal(buf, usermem.ByteOrder, linuxMatcher) - buf = append(buf, []byte{0, 0, 0, 0, 0, 0}...) + buf = append(buf, make([]byte, size-len(buf))...) nflog("convert to binary: marshalled UDP matcher into %v", buf) return buf[:] } @@ -410,7 +404,7 @@ func SetEntries(stack *stack.Stack, optVal []byte) *syserr.Error { } // TODO(gvisor.dev/issue/170): Matchers and targets can specify - // that they only work for certiain protocols, hooks, tables. + // that they only work for certain protocols, hooks, tables. // Get matchers. matchersSize := entry.TargetOffset - linux.SizeOfIPTEntry if len(optVal) < int(matchersSize) { @@ -684,3 +678,8 @@ func hookFromLinux(hook int) iptables.Hook { } panic(fmt.Sprintf("Unknown hook %d does not correspond to a builtin chain", hook)) } + +// alignUp rounds a length up to an alignment. align must be a power of 2. +func alignUp(length int, align uint) int { + return (length + int(align) - 1) & ^(int(align) - 1) +} |