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-rw-r--r--pkg/sentry/socket/netfilter/netfilter.go164
1 files changed, 141 insertions, 23 deletions
diff --git a/pkg/sentry/socket/netfilter/netfilter.go b/pkg/sentry/socket/netfilter/netfilter.go
index e1f2bacce..45296b339 100644
--- a/pkg/sentry/socket/netfilter/netfilter.go
+++ b/pkg/sentry/socket/netfilter/netfilter.go
@@ -131,6 +131,7 @@ func FillDefaultIPTables(stack *stack.Stack) {
stack.SetIPTables(ipt)
}
+// TODO: Return proto.
// convertNetstackToBinary converts the iptables as stored in netstack to the
// format expected by the iptables tool. Linux stores each table as a binary
// blob that can only be traversed by parsing a bit, reading some offsets,
@@ -318,10 +319,12 @@ func SetEntries(stack *stack.Stack, optVal []byte) *syserr.Error {
}
var entry linux.IPTEntry
buf := optVal[:linux.SizeOfIPTEntry]
- optVal = optVal[linux.SizeOfIPTEntry:]
binary.Unmarshal(buf, usermem.ByteOrder, &entry)
- if entry.TargetOffset != linux.SizeOfIPTEntry {
- // TODO(gvisor.dev/issue/170): Support matchers.
+ initialOptValLen := len(optVal)
+ optVal = optVal[linux.SizeOfIPTEntry:]
+
+ if entry.TargetOffset < linux.SizeOfIPTEntry {
+ log.Warningf("netfilter: entry has too-small target offset %d", entry.TargetOffset)
return syserr.ErrInvalidArgument
}
@@ -332,19 +335,41 @@ func SetEntries(stack *stack.Stack, optVal []byte) *syserr.Error {
return err
}
+ // TODO: Matchers (and maybe targets) can specify that they only work for certiain protocols, hooks, tables.
+ // Get matchers.
+ matchersSize := entry.TargetOffset - linux.SizeOfIPTEntry
+ if len(optVal) < int(matchersSize) {
+ log.Warningf("netfilter: entry doesn't have enough room for its matchers (only %d bytes remain)", len(optVal))
+ }
+ matchers, err := parseMatchers(filter, optVal[:matchersSize])
+ if err != nil {
+ log.Warningf("netfilter: failed to parse matchers: %v", err)
+ return err
+ }
+ optVal = optVal[matchersSize:]
+
// Get the target of the rule.
- target, consumed, err := parseTarget(optVal)
+ targetSize := entry.NextOffset - entry.TargetOffset
+ if len(optVal) < int(targetSize) {
+ log.Warningf("netfilter: entry doesn't have enough room for its target (only %d bytes remain)", len(optVal))
+ }
+ target, err := parseTarget(optVal[:targetSize])
if err != nil {
return err
}
- optVal = optVal[consumed:]
+ optVal = optVal[targetSize:]
table.Rules = append(table.Rules, iptables.Rule{
- Filter: filter,
- Target: target,
+ Filter: filter,
+ Target: target,
+ Matchers: matchers,
})
offsets = append(offsets, offset)
- offset += linux.SizeOfIPTEntry + consumed
+ offset += uint32(entry.NextOffset)
+
+ if initialOptValLen-len(optVal) != int(entry.NextOffset) {
+ log.Warningf("netfilter: entry NextOffset is %d, but entry took up %d bytes", entry.NextOffset, initialOptValLen-len(optVal))
+ }
}
// Go through the list of supported hooks for this table and, for each
@@ -401,12 +426,105 @@ func SetEntries(stack *stack.Stack, optVal []byte) *syserr.Error {
return nil
}
-// parseTarget parses a target from the start of optVal and returns the target
-// along with the number of bytes it occupies in optVal.
-func parseTarget(optVal []byte) (iptables.Target, uint32, *syserr.Error) {
+// parseMatchers parses 0 or more matchers from optVal. optVal should contain
+// only the matchers.
+func parseMatchers(filter iptables.IPHeaderFilter, optVal []byte) ([]iptables.Matcher, *syserr.Error) {
+ var matchers []iptables.Matcher
+ for len(optVal) > 0 {
+ log.Infof("parseMatchers: optVal has len %d", len(optVal))
+ // Get the XTEntryMatch.
+ if len(optVal) < linux.SizeOfXTEntryMatch {
+ log.Warningf("netfilter: optVal has insufficient size for entry match: %d", len(optVal))
+ return nil, syserr.ErrInvalidArgument
+ }
+ var match linux.XTEntryMatch
+ buf := optVal[:linux.SizeOfXTEntryMatch]
+ binary.Unmarshal(buf, usermem.ByteOrder, &match)
+ log.Infof("parseMatchers: parsed entry match %q: %+v", match.Name.String(), match)
+
+ // Check some invariants.
+ if match.MatchSize < linux.SizeOfXTEntryMatch {
+ log.Warningf("netfilter: match size is too small, must be at least %d", linux.SizeOfXTEntryMatch)
+ return nil, syserr.ErrInvalidArgument
+ }
+ if len(optVal) < int(match.MatchSize) {
+ log.Warningf("netfilter: optVal has insufficient size for match: %d", len(optVal))
+ return nil, syserr.ErrInvalidArgument
+ }
+
+ buf = optVal[linux.SizeOfXTEntryMatch:match.MatchSize]
+ var matcher iptables.Matcher
+ var err error
+ switch match.Name.String() {
+ case "tcp":
+ if len(buf) < linux.SizeOfXTTCP {
+ log.Warningf("netfilter: optVal has insufficient size for TCP match: %d", len(optVal))
+ return nil, syserr.ErrInvalidArgument
+ }
+ var matchData linux.XTTCP
+ // For alignment reasons, the match's total size may exceed what's
+ // strictly necessary to hold matchData.
+ binary.Unmarshal(buf[:linux.SizeOfXTUDP], usermem.ByteOrder, &matchData)
+ log.Infof("parseMatchers: parsed XTTCP: %+v", matchData)
+ matcher, err = iptables.NewTCPMatcher(filter, iptables.TCPMatcherData{
+ SourcePortStart: matchData.SourcePortStart,
+ SourcePortEnd: matchData.SourcePortEnd,
+ DestinationPortStart: matchData.DestinationPortStart,
+ DestinationPortEnd: matchData.DestinationPortEnd,
+ Option: matchData.Option,
+ FlagMask: matchData.FlagMask,
+ FlagCompare: matchData.FlagCompare,
+ InverseFlags: matchData.InverseFlags,
+ })
+ if err != nil {
+ log.Warningf("netfilter: failed to create TCP matcher: %v", err)
+ return nil, syserr.ErrInvalidArgument
+ }
+
+ case "udp":
+ if len(buf) < linux.SizeOfXTUDP {
+ log.Warningf("netfilter: optVal has insufficient size for UDP match: %d", len(optVal))
+ return nil, syserr.ErrInvalidArgument
+ }
+ var matchData linux.XTUDP
+ // For alignment reasons, the match's total size may exceed what's
+ // strictly necessary to hold matchData.
+ binary.Unmarshal(buf[:linux.SizeOfXTUDP], usermem.ByteOrder, &matchData)
+ log.Infof("parseMatchers: parsed XTUDP: %+v", matchData)
+ matcher, err = iptables.NewUDPMatcher(filter, iptables.UDPMatcherData{
+ SourcePortStart: matchData.SourcePortStart,
+ SourcePortEnd: matchData.SourcePortEnd,
+ DestinationPortStart: matchData.DestinationPortStart,
+ DestinationPortEnd: matchData.DestinationPortEnd,
+ InverseFlags: matchData.InverseFlags,
+ })
+ if err != nil {
+ log.Warningf("netfilter: failed to create UDP matcher: %v", err)
+ return nil, syserr.ErrInvalidArgument
+ }
+
+ default:
+ log.Warningf("netfilter: unsupported matcher with name %q", match.Name.String())
+ return nil, syserr.ErrInvalidArgument
+ }
+
+ matchers = append(matchers, matcher)
+
+ // TODO: Support revision.
+ // TODO: Support proto -- matchers usually specify which proto(s) they work with.
+ optVal = optVal[match.MatchSize:]
+ }
+
+ // TODO: Check that optVal is exhausted.
+ return matchers, nil
+}
+
+// parseTarget parses a target from optVal. optVal should contain only the
+// target.
+func parseTarget(optVal []byte) (iptables.Target, *syserr.Error) {
if len(optVal) < linux.SizeOfXTEntryTarget {
log.Warningf("netfilter: optVal has insufficient size for entry target %d", len(optVal))
- return nil, 0, syserr.ErrInvalidArgument
+ return nil, syserr.ErrInvalidArgument
}
var target linux.XTEntryTarget
buf := optVal[:linux.SizeOfXTEntryTarget]
@@ -414,9 +532,9 @@ func parseTarget(optVal []byte) (iptables.Target, uint32, *syserr.Error) {
switch target.Name.String() {
case "":
// Standard target.
- if len(optVal) < linux.SizeOfXTStandardTarget {
- log.Warningf("netfilter.SetEntries: optVal has insufficient size for standard target %d", len(optVal))
- return nil, 0, syserr.ErrInvalidArgument
+ if len(optVal) != linux.SizeOfXTStandardTarget {
+ log.Warningf("netfilter.SetEntries: optVal has wrong size for standard target %d", len(optVal))
+ return nil, syserr.ErrInvalidArgument
}
var standardTarget linux.XTStandardTarget
buf = optVal[:linux.SizeOfXTStandardTarget]
@@ -424,22 +542,22 @@ func parseTarget(optVal []byte) (iptables.Target, uint32, *syserr.Error) {
verdict, err := translateToStandardVerdict(standardTarget.Verdict)
if err != nil {
- return nil, 0, err
+ return nil, err
}
switch verdict {
case iptables.Accept:
- return iptables.UnconditionalAcceptTarget{}, linux.SizeOfXTStandardTarget, nil
+ return iptables.UnconditionalAcceptTarget{}, nil
case iptables.Drop:
- return iptables.UnconditionalDropTarget{}, linux.SizeOfXTStandardTarget, nil
+ return iptables.UnconditionalDropTarget{}, nil
default:
panic(fmt.Sprintf("Unknown verdict: %v", verdict))
}
case errorTargetName:
// Error target.
- if len(optVal) < linux.SizeOfXTErrorTarget {
+ if len(optVal) != linux.SizeOfXTErrorTarget {
log.Infof("netfilter.SetEntries: optVal has insufficient size for error target %d", len(optVal))
- return nil, 0, syserr.ErrInvalidArgument
+ return nil, syserr.ErrInvalidArgument
}
var errorTarget linux.XTErrorTarget
buf = optVal[:linux.SizeOfXTErrorTarget]
@@ -454,16 +572,16 @@ func parseTarget(optVal []byte) (iptables.Target, uint32, *syserr.Error) {
// rules have an error with the name of the chain.
switch errorTarget.Name.String() {
case errorTargetName:
- return iptables.ErrorTarget{}, linux.SizeOfXTErrorTarget, nil
+ return iptables.ErrorTarget{}, nil
default:
log.Infof("Unknown error target %q doesn't exist or isn't supported yet.", errorTarget.Name.String())
- return nil, 0, syserr.ErrInvalidArgument
+ return nil, syserr.ErrInvalidArgument
}
}
// Unknown target.
log.Infof("Unknown target %q doesn't exist or isn't supported yet.", target.Name.String())
- return nil, 0, syserr.ErrInvalidArgument
+ return nil, syserr.ErrInvalidArgument
}
func filterFromIPTIP(iptip linux.IPTIP) (iptables.IPHeaderFilter, *syserr.Error) {
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-28 21:57:06 +0000