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-rw-r--r--pkg/sentry/socket/netfilter/BUILD1
-rw-r--r--pkg/sentry/socket/netfilter/netfilter.go408
-rw-r--r--pkg/sentry/socket/netstack/netstack.go20
3 files changed, 340 insertions, 89 deletions
diff --git a/pkg/sentry/socket/netfilter/BUILD b/pkg/sentry/socket/netfilter/BUILD
index 5eb06bbf4..b70047d81 100644
--- a/pkg/sentry/socket/netfilter/BUILD
+++ b/pkg/sentry/socket/netfilter/BUILD
@@ -14,6 +14,7 @@ go_library(
deps = [
"//pkg/abi/linux",
"//pkg/binary",
+ "//pkg/log",
"//pkg/sentry/kernel",
"//pkg/sentry/usermem",
"//pkg/syserr",
diff --git a/pkg/sentry/socket/netfilter/netfilter.go b/pkg/sentry/socket/netfilter/netfilter.go
index 9f87c32f1..a9cfc1749 100644
--- a/pkg/sentry/socket/netfilter/netfilter.go
+++ b/pkg/sentry/socket/netfilter/netfilter.go
@@ -21,6 +21,7 @@ import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/binary"
+ "gvisor.dev/gvisor/pkg/log"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserr"
@@ -35,6 +36,7 @@ const errorTargetName = "ERROR"
// metadata is opaque to netstack. It holds data that we need to translate
// between Linux's and netstack's iptables representations.
+// TODO(gvisor.dev/issue/170): This might be removable.
type metadata struct {
HookEntry [linux.NF_INET_NUMHOOKS]uint32
Underflow [linux.NF_INET_NUMHOOKS]uint32
@@ -51,7 +53,7 @@ func GetInfo(t *kernel.Task, ep tcpip.Endpoint, outPtr usermem.Addr) (linux.IPTG
}
// Find the appropriate table.
- table, err := findTable(ep, info.TableName())
+ table, err := findTable(ep, info.Name)
if err != nil {
return linux.IPTGetinfo{}, err
}
@@ -82,30 +84,31 @@ func GetEntries(t *kernel.Task, ep tcpip.Endpoint, outPtr usermem.Addr, outLen i
}
// Find the appropriate table.
- table, err := findTable(ep, userEntries.TableName())
+ table, err := findTable(ep, userEntries.Name)
if err != nil {
return linux.KernelIPTGetEntries{}, err
}
// Convert netstack's iptables rules to something that the iptables
// tool can understand.
- entries, _, err := convertNetstackToBinary(userEntries.TableName(), table)
+ entries, _, err := convertNetstackToBinary(userEntries.Name.String(), table)
if err != nil {
return linux.KernelIPTGetEntries{}, err
}
if binary.Size(entries) > uintptr(outLen) {
+ log.Warningf("Insufficient GetEntries output size: %d", uintptr(outLen))
return linux.KernelIPTGetEntries{}, syserr.ErrInvalidArgument
}
return entries, nil
}
-func findTable(ep tcpip.Endpoint, tableName string) (iptables.Table, *syserr.Error) {
+func findTable(ep tcpip.Endpoint, tablename linux.TableName) (iptables.Table, *syserr.Error) {
ipt, err := ep.IPTables()
if err != nil {
return iptables.Table{}, syserr.FromError(err)
}
- table, ok := ipt.Tables[tableName]
+ table, ok := ipt.Tables[tablename.String()]
if !ok {
return iptables.Table{}, syserr.ErrInvalidArgument
}
@@ -135,110 +138,68 @@ func FillDefaultIPTables(stack *stack.Stack) {
// 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,
// jumping to those offsets, parsing again, etc.
-func convertNetstackToBinary(name string, table iptables.Table) (linux.KernelIPTGetEntries, metadata, *syserr.Error) {
+func convertNetstackToBinary(tablename string, table iptables.Table) (linux.KernelIPTGetEntries, metadata, *syserr.Error) {
// Return values.
var entries linux.KernelIPTGetEntries
var meta metadata
// The table name has to fit in the struct.
- if linux.XT_TABLE_MAXNAMELEN < len(name) {
+ if linux.XT_TABLE_MAXNAMELEN < len(tablename) {
+ log.Warningf("Table name %q too long.", tablename)
return linux.KernelIPTGetEntries{}, metadata{}, syserr.ErrInvalidArgument
}
- copy(entries.Name[:], name)
-
- // Deal with the built in chains first (INPUT, OUTPUT, etc.). Each of
- // these chains ends with an unconditional policy entry.
- for hook := iptables.Prerouting; hook < iptables.NumHooks; hook++ {
- chain, ok := table.BuiltinChains[hook]
- if !ok {
- // This table doesn't support this hook.
- continue
- }
-
- // Sanity check.
- if len(chain.Rules) < 1 {
- return linux.KernelIPTGetEntries{}, metadata{}, syserr.ErrInvalidArgument
- }
+ copy(entries.Name[:], tablename)
- for ruleIdx, rule := range chain.Rules {
- // If this is the first rule of a builtin chain, set
- // the metadata hook entry point.
- if ruleIdx == 0 {
+ for ruleIdx, rule := range table.Rules {
+ // Is this a chain entry point?
+ for hook, hookRuleIdx := range table.BuiltinChains {
+ if hookRuleIdx == ruleIdx {
meta.HookEntry[hook] = entries.Size
}
-
- // Each rule corresponds to an entry.
- entry := linux.KernelIPTEntry{
- IPTEntry: linux.IPTEntry{
- NextOffset: linux.SizeOfIPTEntry,
- TargetOffset: linux.SizeOfIPTEntry,
- },
+ }
+ // Is this a chain underflow point?
+ for underflow, underflowRuleIdx := range table.Underflows {
+ if underflowRuleIdx == ruleIdx {
+ meta.Underflow[underflow] = entries.Size
}
+ }
- for _, matcher := range rule.Matchers {
- // Serialize the matcher and add it to the
- // entry.
- serialized := marshalMatcher(matcher)
- entry.Elems = append(entry.Elems, serialized...)
- entry.NextOffset += uint16(len(serialized))
- entry.TargetOffset += uint16(len(serialized))
- }
+ // Each rule corresponds to an entry.
+ entry := linux.KernelIPTEntry{
+ IPTEntry: linux.IPTEntry{
+ NextOffset: linux.SizeOfIPTEntry,
+ TargetOffset: linux.SizeOfIPTEntry,
+ },
+ }
- // Serialize and append the target.
- serialized := marshalTarget(rule.Target)
+ for _, matcher := range rule.Matchers {
+ // Serialize the matcher and add it to the
+ // entry.
+ serialized := marshalMatcher(matcher)
entry.Elems = append(entry.Elems, serialized...)
entry.NextOffset += uint16(len(serialized))
-
- // The underflow rule is the last rule in the chain,
- // and is an unconditional rule (i.e. it matches any
- // packet). This is enforced when saving iptables.
- if ruleIdx == len(chain.Rules)-1 {
- meta.Underflow[hook] = entries.Size
- }
-
- entries.Size += uint32(entry.NextOffset)
- entries.Entrytable = append(entries.Entrytable, entry)
- meta.NumEntries++
+ entry.TargetOffset += uint16(len(serialized))
}
- }
-
- // TODO(gvisor.dev/issue/170): Deal with the user chains here. Each of
- // these starts with an error node holding the chain's name and ends
- // with an unconditional return.
+ // Serialize and append the target.
+ serialized := marshalTarget(rule.Target)
+ entry.Elems = append(entry.Elems, serialized...)
+ entry.NextOffset += uint16(len(serialized))
- // Lastly, each table ends with an unconditional error target rule as
- // its final entry.
- errorEntry := linux.KernelIPTEntry{
- IPTEntry: linux.IPTEntry{
- NextOffset: linux.SizeOfIPTEntry,
- TargetOffset: linux.SizeOfIPTEntry,
- },
+ entries.Size += uint32(entry.NextOffset)
+ entries.Entrytable = append(entries.Entrytable, entry)
+ meta.NumEntries++
}
- var errorTarget linux.XTErrorTarget
- errorTarget.Target.TargetSize = linux.SizeOfXTErrorTarget
- copy(errorTarget.ErrorName[:], errorTargetName)
- copy(errorTarget.Target.Name[:], errorTargetName)
-
- // Serialize and add it to the list of entries.
- errorTargetBuf := make([]byte, 0, linux.SizeOfXTErrorTarget)
- serializedErrorTarget := binary.Marshal(errorTargetBuf, usermem.ByteOrder, errorTarget)
- errorEntry.Elems = append(errorEntry.Elems, serializedErrorTarget...)
- errorEntry.NextOffset += uint16(len(serializedErrorTarget))
-
- entries.Size += uint32(errorEntry.NextOffset)
- entries.Entrytable = append(entries.Entrytable, errorEntry)
- meta.NumEntries++
- meta.Size = entries.Size
+ meta.Size = entries.Size
return entries, meta, nil
}
func marshalMatcher(matcher iptables.Matcher) []byte {
switch matcher.(type) {
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): We don't support any matchers
+ // yet, so any call to marshalMatcher will panic.
panic(fmt.Errorf("unknown matcher of type %T", matcher))
}
}
@@ -246,28 +207,46 @@ func marshalMatcher(matcher iptables.Matcher) []byte {
func marshalTarget(target iptables.Target) []byte {
switch target.(type) {
case iptables.UnconditionalAcceptTarget:
- return marshalUnconditionalAcceptTarget()
+ return marshalStandardTarget(iptables.Accept)
+ case iptables.UnconditionalDropTarget:
+ return marshalStandardTarget(iptables.Drop)
+ case iptables.ErrorTarget:
+ return marshalErrorTarget()
default:
panic(fmt.Errorf("unknown target of type %T", target))
}
}
-func marshalUnconditionalAcceptTarget() []byte {
+func marshalStandardTarget(verdict iptables.Verdict) []byte {
// The target's name will be the empty string.
target := linux.XTStandardTarget{
Target: linux.XTEntryTarget{
TargetSize: linux.SizeOfXTStandardTarget,
},
- Verdict: translateStandardVerdict(iptables.Accept),
+ Verdict: translateFromStandardVerdict(verdict),
}
ret := make([]byte, 0, linux.SizeOfXTStandardTarget)
return binary.Marshal(ret, usermem.ByteOrder, target)
}
-// translateStandardVerdict translates verdicts the same way as the iptables
+func marshalErrorTarget() []byte {
+ // This is an error target named error
+ target := linux.XTErrorTarget{
+ Target: linux.XTEntryTarget{
+ TargetSize: linux.SizeOfXTErrorTarget,
+ },
+ }
+ copy(target.Name[:], errorTargetName)
+ copy(target.Target.Name[:], errorTargetName)
+
+ ret := make([]byte, 0, linux.SizeOfXTErrorTarget)
+ return binary.Marshal(ret, usermem.ByteOrder, target)
+}
+
+// translateFromStandardVerdict translates verdicts the same way as the iptables
// tool.
-func translateStandardVerdict(verdict iptables.Verdict) int32 {
+func translateFromStandardVerdict(verdict iptables.Verdict) int32 {
switch verdict {
case iptables.Accept:
return -linux.NF_ACCEPT - 1
@@ -280,7 +259,258 @@ func translateStandardVerdict(verdict iptables.Verdict) int32 {
case iptables.Jump:
// TODO(gvisor.dev/issue/170): Support Jump.
panic("Jump isn't supported yet")
+ }
+ panic(fmt.Sprintf("unknown standard verdict: %d", verdict))
+}
+
+// translateToStandardVerdict translates from the value in a
+// linux.XTStandardTarget to an iptables.Verdict.
+func translateToStandardVerdict(val int32) (iptables.Verdict, *syserr.Error) {
+ // TODO(gvisor.dev/issue/170): Support other verdicts.
+ switch val {
+ case -linux.NF_ACCEPT - 1:
+ return iptables.Accept, nil
+ case -linux.NF_DROP - 1:
+ return iptables.Drop, nil
+ case -linux.NF_QUEUE - 1:
+ log.Warningf("Unsupported iptables verdict QUEUE.")
+ case linux.NF_RETURN:
+ log.Warningf("Unsupported iptables verdict RETURN.")
+ default:
+ log.Warningf("Unknown iptables verdict %d.", val)
+ }
+ return iptables.Invalid, syserr.ErrInvalidArgument
+}
+
+// SetEntries sets iptables rules for a single table. See
+// net/ipv4/netfilter/ip_tables.c:translate_table for reference.
+func SetEntries(stack *stack.Stack, optVal []byte) *syserr.Error {
+ printReplace(optVal)
+
+ // Get the basic rules data (struct ipt_replace).
+ if len(optVal) < linux.SizeOfIPTReplace {
+ log.Warningf("netfilter.SetEntries: optVal has insufficient size for replace %d", len(optVal))
+ return syserr.ErrInvalidArgument
+ }
+ var replace linux.IPTReplace
+ replaceBuf := optVal[:linux.SizeOfIPTReplace]
+ optVal = optVal[linux.SizeOfIPTReplace:]
+ binary.Unmarshal(replaceBuf, usermem.ByteOrder, &replace)
+
+ // TODO(gvisor.dev/issue/170): Support other tables.
+ var table iptables.Table
+ switch replace.Name.String() {
+ case iptables.TablenameFilter:
+ table = iptables.EmptyFilterTable()
default:
- panic(fmt.Sprintf("unknown standard verdict: %d", verdict))
+ log.Warningf("We don't yet support writing to the %q table (gvisor.dev/issue/170)", replace.Name.String())
+ return syserr.ErrInvalidArgument
+ }
+
+ // Convert input into a list of rules and their offsets.
+ var offset uint32
+ var offsets []uint32
+ for entryIdx := uint32(0); entryIdx < replace.NumEntries; entryIdx++ {
+ // Get the struct ipt_entry.
+ if len(optVal) < linux.SizeOfIPTEntry {
+ log.Warningf("netfilter: optVal has insufficient size for entry %d", len(optVal))
+ return syserr.ErrInvalidArgument
+ }
+ 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.
+ 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
+ }
+
+ // Get the target of the rule.
+ target, consumed, err := parseTarget(optVal)
+ if err != nil {
+ return err
+ }
+ optVal = optVal[consumed:]
+
+ table.Rules = append(table.Rules, iptables.Rule{Target: target})
+ offsets = append(offsets, offset)
+ offset += linux.SizeOfIPTEntry + consumed
+ }
+
+ // Go through the list of supported hooks for this table and, for each
+ // one, set the rule it corresponds to.
+ for hook, _ := range replace.HookEntry {
+ if table.ValidHooks()&uint32(hook) != 0 {
+ hk := hookFromLinux(hook)
+ for ruleIdx, offset := range offsets {
+ if offset == replace.HookEntry[hook] {
+ table.BuiltinChains[hk] = ruleIdx
+ }
+ if offset == replace.Underflow[hook] {
+ table.Underflows[hk] = ruleIdx
+ }
+ }
+ if ruleIdx := table.BuiltinChains[hk]; ruleIdx == iptables.HookUnset {
+ log.Warningf("Hook %v is unset.", hk)
+ return syserr.ErrInvalidArgument
+ }
+ if ruleIdx := table.Underflows[hk]; ruleIdx == iptables.HookUnset {
+ log.Warningf("Underflow %v is unset.", hk)
+ return syserr.ErrInvalidArgument
+ }
+ }
+ }
+
+ ipt := stack.IPTables()
+ table.SetMetadata(metadata{
+ HookEntry: replace.HookEntry,
+ Underflow: replace.Underflow,
+ NumEntries: replace.NumEntries,
+ Size: replace.Size,
+ })
+ ipt.Tables[replace.Name.String()] = table
+ stack.SetIPTables(ipt)
+
+ 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) {
+ if len(optVal) < linux.SizeOfXTEntryTarget {
+ log.Warningf("netfilter: optVal has insufficient size for entry target %d", len(optVal))
+ return nil, 0, syserr.ErrInvalidArgument
+ }
+ var target linux.XTEntryTarget
+ buf := optVal[:linux.SizeOfXTEntryTarget]
+ binary.Unmarshal(buf, usermem.ByteOrder, &target)
+ 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
+ }
+ var standardTarget linux.XTStandardTarget
+ buf = optVal[:linux.SizeOfXTStandardTarget]
+ binary.Unmarshal(buf, usermem.ByteOrder, &standardTarget)
+
+ verdict, err := translateToStandardVerdict(standardTarget.Verdict)
+ if err != nil {
+ return nil, 0, err
+ }
+ switch verdict {
+ case iptables.Accept:
+ return iptables.UnconditionalAcceptTarget{}, linux.SizeOfXTStandardTarget, nil
+ case iptables.Drop:
+ // TODO(gvisor.dev/issue/170): Return an
+ // iptables.UnconditionalDropTarget to support DROP.
+ log.Infof("netfilter DROP is not supported yet.")
+ return nil, 0, syserr.ErrInvalidArgument
+ default:
+ panic(fmt.Sprintf("Unknown verdict: %v", verdict))
+ }
+
+ case errorTargetName:
+ // Error target.
+ if len(optVal) < linux.SizeOfXTErrorTarget {
+ log.Infof("netfilter.SetEntries: optVal has insufficient size for error target %d", len(optVal))
+ return nil, 0, syserr.ErrInvalidArgument
+ }
+ var errorTarget linux.XTErrorTarget
+ buf = optVal[:linux.SizeOfXTErrorTarget]
+ binary.Unmarshal(buf, usermem.ByteOrder, &errorTarget)
+
+ // Error targets are used in 2 cases:
+ // * An actual error case. These rules have an error
+ // named errorTargetName. The last entry of the table
+ // is usually an error case to catch any packets that
+ // somehow fall through every rule.
+ // * To mark the start of a user defined chain. These
+ // rules have an error with the name of the chain.
+ switch errorTarget.Name.String() {
+ case errorTargetName:
+ return iptables.ErrorTarget{}, linux.SizeOfXTErrorTarget, nil
+ default:
+ log.Infof("Unknown error target %q doesn't exist or isn't supported yet.", errorTarget.Name.String())
+ return nil, 0, 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
+}
+
+func hookFromLinux(hook int) iptables.Hook {
+ switch hook {
+ case linux.NF_INET_PRE_ROUTING:
+ return iptables.Prerouting
+ case linux.NF_INET_LOCAL_IN:
+ return iptables.Input
+ case linux.NF_INET_FORWARD:
+ return iptables.Forward
+ case linux.NF_INET_LOCAL_OUT:
+ return iptables.Output
+ case linux.NF_INET_POST_ROUTING:
+ return iptables.Postrouting
+ }
+ panic(fmt.Sprintf("Unknown hook %d does not correspond to a builtin chain", hook))
+}
+
+// printReplace prints information about the struct ipt_replace in optVal. It
+// is only for debugging.
+func printReplace(optVal []byte) {
+ // Basic replace info.
+ var replace linux.IPTReplace
+ replaceBuf := optVal[:linux.SizeOfIPTReplace]
+ optVal = optVal[linux.SizeOfIPTReplace:]
+ binary.Unmarshal(replaceBuf, usermem.ByteOrder, &replace)
+ log.Infof("Replacing table %q: %+v", replace.Name.String(), replace)
+
+ // Read in the list of entries at the end of replace.
+ var totalOffset uint16
+ for entryIdx := uint32(0); entryIdx < replace.NumEntries; entryIdx++ {
+ var entry linux.IPTEntry
+ entryBuf := optVal[:linux.SizeOfIPTEntry]
+ binary.Unmarshal(entryBuf, usermem.ByteOrder, &entry)
+ log.Infof("Entry %d (total offset %d): %+v", entryIdx, totalOffset, entry)
+
+ totalOffset += entry.NextOffset
+ if entry.TargetOffset == linux.SizeOfIPTEntry {
+ log.Infof("Entry has no matches.")
+ } else {
+ log.Infof("Entry has matches.")
+ }
+
+ var target linux.XTEntryTarget
+ targetBuf := optVal[entry.TargetOffset : entry.TargetOffset+linux.SizeOfXTEntryTarget]
+ binary.Unmarshal(targetBuf, usermem.ByteOrder, &target)
+ log.Infof("Target named %q: %+v", target.Name.String(), target)
+
+ switch target.Name.String() {
+ case "":
+ var standardTarget linux.XTStandardTarget
+ stBuf := optVal[entry.TargetOffset : entry.TargetOffset+linux.SizeOfXTStandardTarget]
+ binary.Unmarshal(stBuf, usermem.ByteOrder, &standardTarget)
+ log.Infof("Standard target with verdict %q (%d).", linux.VerdictStrings[standardTarget.Verdict], standardTarget.Verdict)
+ case errorTargetName:
+ var errorTarget linux.XTErrorTarget
+ etBuf := optVal[entry.TargetOffset : entry.TargetOffset+linux.SizeOfXTErrorTarget]
+ binary.Unmarshal(etBuf, usermem.ByteOrder, &errorTarget)
+ log.Infof("Error target with name %q.", errorTarget.Name.String())
+ default:
+ log.Infof("Unknown target type.")
+ }
+
+ optVal = optVal[entry.NextOffset:]
}
}
diff --git a/pkg/sentry/socket/netstack/netstack.go b/pkg/sentry/socket/netstack/netstack.go
index 0affb8071..099319327 100644
--- a/pkg/sentry/socket/netstack/netstack.go
+++ b/pkg/sentry/socket/netstack/netstack.go
@@ -1377,6 +1377,26 @@ func (s *SocketOperations) SetSockOpt(t *kernel.Task, level int, name int, optVa
return nil
}
+ if s.skType == linux.SOCK_RAW && level == linux.IPPROTO_IP {
+ switch name {
+ case linux.IPT_SO_SET_REPLACE:
+ if len(optVal) < linux.SizeOfIPTReplace {
+ return syserr.ErrInvalidArgument
+ }
+
+ stack := inet.StackFromContext(t)
+ if stack == nil {
+ return syserr.ErrNoDevice
+ }
+ // Stack must be a netstack stack.
+ return netfilter.SetEntries(stack.(*Stack).Stack, optVal)
+
+ case linux.IPT_SO_SET_ADD_COUNTERS:
+ // TODO(gvisor.dev/issue/170): Counter support.
+ return nil
+ }
+ }
+
return SetSockOpt(t, s, s.Endpoint, level, name, optVal)
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-11 14:45:44 +0000