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-rw-r--r--pkg/abi/linux/netfilter.go89
-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
-rw-r--r--pkg/sentry/syscalls/linux/sys_socket.go2
-rw-r--r--pkg/tcpip/iptables/BUILD5
-rw-r--r--pkg/tcpip/iptables/iptables.go120
-rw-r--r--pkg/tcpip/iptables/targets.go16
-rw-r--r--pkg/tcpip/iptables/types.go49
9 files changed, 515 insertions, 195 deletions
diff --git a/pkg/abi/linux/netfilter.go b/pkg/abi/linux/netfilter.go
index 269ba5567..33fcc6c95 100644
--- a/pkg/abi/linux/netfilter.go
+++ b/pkg/abi/linux/netfilter.go
@@ -42,6 +42,15 @@ const (
NF_RETURN = -NF_REPEAT - 1
)
+// VerdictStrings maps int verdicts to the strings they represent. It is used
+// for debugging.
+var VerdictStrings = map[int32]string{
+ -NF_DROP - 1: "DROP",
+ -NF_ACCEPT - 1: "ACCEPT",
+ -NF_QUEUE - 1: "QUEUE",
+ NF_RETURN: "RETURN",
+}
+
// Socket options. These correspond to values in
// include/uapi/linux/netfilter_ipv4/ip_tables.h.
const (
@@ -179,7 +188,7 @@ const SizeOfXTCounters = 16
// the user data.
type XTEntryMatch struct {
MatchSize uint16
- Name [XT_EXTENSION_MAXNAMELEN]byte
+ Name ExtensionName
Revision uint8
// Data is omitted here because it would cause XTEntryMatch to be an
// extra byte larger (see http://www.catb.org/esr/structure-packing/).
@@ -199,7 +208,7 @@ const SizeOfXTEntryMatch = 32
// the user data.
type XTEntryTarget struct {
TargetSize uint16
- Name [XT_EXTENSION_MAXNAMELEN]byte
+ Name ExtensionName
Revision uint8
// Data is omitted here because it would cause XTEntryTarget to be an
// extra byte larger (see http://www.catb.org/esr/structure-packing/).
@@ -226,9 +235,9 @@ const SizeOfXTStandardTarget = 40
// ErrorName. It corresponds to struct xt_error_target in
// include/uapi/linux/netfilter/x_tables.h.
type XTErrorTarget struct {
- Target XTEntryTarget
- ErrorName [XT_FUNCTION_MAXNAMELEN]byte
- _ [2]byte
+ Target XTEntryTarget
+ Name ErrorName
+ _ [2]byte
}
// SizeOfXTErrorTarget is the size of an XTErrorTarget.
@@ -237,7 +246,7 @@ const SizeOfXTErrorTarget = 64
// IPTGetinfo is the argument for the IPT_SO_GET_INFO sockopt. It corresponds
// to struct ipt_getinfo in include/uapi/linux/netfilter_ipv4/ip_tables.h.
type IPTGetinfo struct {
- Name [XT_TABLE_MAXNAMELEN]byte
+ Name TableName
ValidHooks uint32
HookEntry [NF_INET_NUMHOOKS]uint32
Underflow [NF_INET_NUMHOOKS]uint32
@@ -248,16 +257,11 @@ type IPTGetinfo struct {
// SizeOfIPTGetinfo is the size of an IPTGetinfo.
const SizeOfIPTGetinfo = 84
-// TableName returns the table name.
-func (info *IPTGetinfo) TableName() string {
- return tableName(info.Name[:])
-}
-
// IPTGetEntries is the argument for the IPT_SO_GET_ENTRIES sockopt. It
// corresponds to struct ipt_get_entries in
// include/uapi/linux/netfilter_ipv4/ip_tables.h.
type IPTGetEntries struct {
- Name [XT_TABLE_MAXNAMELEN]byte
+ Name TableName
Size uint32
_ [4]byte
// Entrytable is omitted here because it would cause IPTGetEntries to
@@ -266,34 +270,22 @@ type IPTGetEntries struct {
// Entrytable [0]IPTEntry
}
-// TableName returns the entries' table name.
-func (entries *IPTGetEntries) TableName() string {
- return tableName(entries.Name[:])
-}
-
// SizeOfIPTGetEntries is the size of an IPTGetEntries.
const SizeOfIPTGetEntries = 40
-// KernelIPTGetEntries is identical to IPTEntry, but includes the Elems field.
-// This struct marshaled via the binary package to write an KernelIPTGetEntries
-// to userspace.
+// KernelIPTGetEntries is identical to IPTGetEntries, but includes the
+// Entrytable field. This struct marshaled via the binary package to write an
+// KernelIPTGetEntries to userspace.
type KernelIPTGetEntries struct {
- Name [XT_TABLE_MAXNAMELEN]byte
- Size uint32
- _ [4]byte
+ IPTGetEntries
Entrytable []KernelIPTEntry
}
-// TableName returns the entries' table name.
-func (entries *KernelIPTGetEntries) TableName() string {
- return tableName(entries.Name[:])
-}
-
// IPTReplace is the argument for the IPT_SO_SET_REPLACE sockopt. It
// corresponds to struct ipt_replace in
// include/uapi/linux/netfilter_ipv4/ip_tables.h.
type IPTReplace struct {
- Name [XT_TABLE_MAXNAMELEN]byte
+ Name TableName
ValidHooks uint32
NumEntries uint32
Size uint32
@@ -306,14 +298,45 @@ type IPTReplace struct {
// Entries [0]IPTEntry
}
+// KernelIPTReplace is identical to IPTReplace, but includes the Entries field.
+type KernelIPTReplace struct {
+ IPTReplace
+ Entries [0]IPTEntry
+}
+
// SizeOfIPTReplace is the size of an IPTReplace.
const SizeOfIPTReplace = 96
-func tableName(name []byte) string {
- for i, c := range name {
+// ExtensionName holds the name of a netfilter extension.
+type ExtensionName [XT_EXTENSION_MAXNAMELEN]byte
+
+// String implements fmt.Stringer.
+func (en ExtensionName) String() string {
+ return goString(en[:])
+}
+
+// TableName holds the name of a netfilter table.
+type TableName [XT_TABLE_MAXNAMELEN]byte
+
+// String implements fmt.Stringer.
+func (tn TableName) String() string {
+ return goString(tn[:])
+}
+
+// ErrorName holds the name of a netfilter error. These can also hold
+// user-defined chains.
+type ErrorName [XT_FUNCTION_MAXNAMELEN]byte
+
+// String implements fmt.Stringer.
+func (en ErrorName) String() string {
+ return goString(en[:])
+}
+
+func goString(cstring []byte) string {
+ for i, c := range cstring {
if c == 0 {
- return string(name[:i])
+ return string(cstring[:i])
}
}
- return string(name)
+ return string(cstring)
}
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)
}
diff --git a/pkg/sentry/syscalls/linux/sys_socket.go b/pkg/sentry/syscalls/linux/sys_socket.go
index 4b5aafcc0..cda517a81 100644
--- a/pkg/sentry/syscalls/linux/sys_socket.go
+++ b/pkg/sentry/syscalls/linux/sys_socket.go
@@ -41,7 +41,7 @@ const maxListenBacklog = 1024
const maxAddrLen = 200
// maxOptLen is the maximum sockopt parameter length we're willing to accept.
-const maxOptLen = 1024
+const maxOptLen = 1024 * 8
// maxControlLen is the maximum length of the msghdr.msg_control buffer we're
// willing to accept. Note that this limit is smaller than Linux, which allows
diff --git a/pkg/tcpip/iptables/BUILD b/pkg/tcpip/iptables/BUILD
index cc5f531e2..64769c333 100644
--- a/pkg/tcpip/iptables/BUILD
+++ b/pkg/tcpip/iptables/BUILD
@@ -11,5 +11,8 @@ go_library(
],
importpath = "gvisor.dev/gvisor/pkg/tcpip/iptables",
visibility = ["//visibility:public"],
- deps = ["//pkg/tcpip/buffer"],
+ deps = [
+ "//pkg/log",
+ "//pkg/tcpip/buffer",
+ ],
)
diff --git a/pkg/tcpip/iptables/iptables.go b/pkg/tcpip/iptables/iptables.go
index 68c68d4aa..647970133 100644
--- a/pkg/tcpip/iptables/iptables.go
+++ b/pkg/tcpip/iptables/iptables.go
@@ -16,66 +16,114 @@
// tool.
package iptables
+// Table names.
const (
- tablenameNat = "nat"
- tablenameMangle = "mangle"
+ TablenameNat = "nat"
+ TablenameMangle = "mangle"
+ TablenameFilter = "filter"
)
// Chain names as defined by net/ipv4/netfilter/ip_tables.c.
const (
- chainNamePrerouting = "PREROUTING"
- chainNameInput = "INPUT"
- chainNameForward = "FORWARD"
- chainNameOutput = "OUTPUT"
- chainNamePostrouting = "POSTROUTING"
+ ChainNamePrerouting = "PREROUTING"
+ ChainNameInput = "INPUT"
+ ChainNameForward = "FORWARD"
+ ChainNameOutput = "OUTPUT"
+ ChainNamePostrouting = "POSTROUTING"
)
+// HookUnset indicates that there is no hook set for an entrypoint or
+// underflow.
+const HookUnset = -1
+
// DefaultTables returns a default set of tables. Each chain is set to accept
// all packets.
func DefaultTables() IPTables {
+ // TODO(gvisor.dev/issue/170): We may be able to swap out some strings for
+ // iotas.
return IPTables{
Tables: map[string]Table{
- tablenameNat: Table{
- BuiltinChains: map[Hook]Chain{
- Prerouting: unconditionalAcceptChain(chainNamePrerouting),
- Input: unconditionalAcceptChain(chainNameInput),
- Output: unconditionalAcceptChain(chainNameOutput),
- Postrouting: unconditionalAcceptChain(chainNamePostrouting),
+ TablenameNat: Table{
+ Rules: []Rule{
+ Rule{Target: UnconditionalAcceptTarget{}},
+ Rule{Target: UnconditionalAcceptTarget{}},
+ Rule{Target: UnconditionalAcceptTarget{}},
+ Rule{Target: UnconditionalAcceptTarget{}},
+ Rule{Target: ErrorTarget{}},
+ },
+ BuiltinChains: map[Hook]int{
+ Prerouting: 0,
+ Input: 1,
+ Output: 2,
+ Postrouting: 3,
},
- DefaultTargets: map[Hook]Target{
- Prerouting: UnconditionalAcceptTarget{},
- Input: UnconditionalAcceptTarget{},
- Output: UnconditionalAcceptTarget{},
- Postrouting: UnconditionalAcceptTarget{},
+ Underflows: map[Hook]int{
+ Prerouting: 0,
+ Input: 1,
+ Output: 2,
+ Postrouting: 3,
},
- UserChains: map[string]Chain{},
+ UserChains: map[string]int{},
},
- tablenameMangle: Table{
- BuiltinChains: map[Hook]Chain{
- Prerouting: unconditionalAcceptChain(chainNamePrerouting),
- Output: unconditionalAcceptChain(chainNameOutput),
+ TablenameMangle: Table{
+ Rules: []Rule{
+ Rule{Target: UnconditionalAcceptTarget{}},
+ Rule{Target: UnconditionalAcceptTarget{}},
+ Rule{Target: ErrorTarget{}},
+ },
+ BuiltinChains: map[Hook]int{
+ Prerouting: 0,
+ Output: 1,
},
- DefaultTargets: map[Hook]Target{
- Prerouting: UnconditionalAcceptTarget{},
- Output: UnconditionalAcceptTarget{},
+ Underflows: map[Hook]int{
+ Prerouting: 0,
+ Output: 1,
},
- UserChains: map[string]Chain{},
+ UserChains: map[string]int{},
+ },
+ TablenameFilter: Table{
+ Rules: []Rule{
+ Rule{Target: UnconditionalAcceptTarget{}},
+ Rule{Target: UnconditionalAcceptTarget{}},
+ Rule{Target: UnconditionalAcceptTarget{}},
+ Rule{Target: ErrorTarget{}},
+ },
+ BuiltinChains: map[Hook]int{
+ Input: 0,
+ Forward: 1,
+ Output: 2,
+ },
+ Underflows: map[Hook]int{
+ Input: 0,
+ Forward: 1,
+ Output: 2,
+ },
+ UserChains: map[string]int{},
},
},
Priorities: map[Hook][]string{
- Prerouting: []string{tablenameMangle, tablenameNat},
- Output: []string{tablenameMangle, tablenameNat},
+ Input: []string{TablenameNat, TablenameFilter},
+ Prerouting: []string{TablenameMangle, TablenameNat},
+ Output: []string{TablenameMangle, TablenameNat, TablenameFilter},
},
}
}
-func unconditionalAcceptChain(name string) Chain {
- return Chain{
- Name: name,
- Rules: []Rule{
- Rule{
- Target: UnconditionalAcceptTarget{},
- },
+// EmptyFilterTable returns a Table with no rules and the filter table chains
+// mapped to HookUnset.
+func EmptyFilterTable() Table {
+ return Table{
+ Rules: []Rule{},
+ BuiltinChains: map[Hook]int{
+ Input: HookUnset,
+ Forward: HookUnset,
+ Output: HookUnset,
+ },
+ Underflows: map[Hook]int{
+ Input: HookUnset,
+ Forward: HookUnset,
+ Output: HookUnset,
},
+ UserChains: map[string]int{},
}
}
diff --git a/pkg/tcpip/iptables/targets.go b/pkg/tcpip/iptables/targets.go
index 19a7f77e3..b94a4c941 100644
--- a/pkg/tcpip/iptables/targets.go
+++ b/pkg/tcpip/iptables/targets.go
@@ -16,7 +16,10 @@
package iptables
-import "gvisor.dev/gvisor/pkg/tcpip/buffer"
+import (
+ "gvisor.dev/gvisor/pkg/log"
+ "gvisor.dev/gvisor/pkg/tcpip/buffer"
+)
// UnconditionalAcceptTarget accepts all packets.
type UnconditionalAcceptTarget struct{}
@@ -33,3 +36,14 @@ type UnconditionalDropTarget struct{}
func (UnconditionalDropTarget) Action(packet buffer.VectorisedView) (Verdict, string) {
return Drop, ""
}
+
+// ErrorTarget logs an error and drops the packet. It represents a target that
+// should be unreachable.
+type ErrorTarget struct{}
+
+// Action implements Target.Action.
+func (ErrorTarget) Action(packet buffer.VectorisedView) (Verdict, string) {
+ log.Warningf("ErrorTarget triggered.")
+ return Drop, ""
+
+}
diff --git a/pkg/tcpip/iptables/types.go b/pkg/tcpip/iptables/types.go
index 42a79ef9f..540f8c0b4 100644
--- a/pkg/tcpip/iptables/types.go
+++ b/pkg/tcpip/iptables/types.go
@@ -61,9 +61,12 @@ const (
type Verdict int
const (
+ // Invalid indicates an unkonwn or erroneous verdict.
+ Invalid Verdict = iota
+
// Accept indicates the packet should continue traversing netstack as
// normal.
- Accept Verdict = iota
+ Accept
// Drop inicates the packet should be dropped, stopping traversing
// netstack.
@@ -104,29 +107,22 @@ type IPTables struct {
Priorities map[Hook][]string
}
-// A Table defines a set of chains and hooks into the network stack. The
-// currently supported tables are:
-// * nat
-// * mangle
+// A Table defines a set of chains and hooks into the network stack. It is
+// really just a list of rules with some metadata for entrypoints and such.
type Table struct {
- // BuiltinChains holds the un-deletable chains built into netstack. If
- // a hook isn't present in the map, this table doesn't utilize that
- // hook.
- BuiltinChains map[Hook]Chain
+ // Rules holds the rules that make up the table.
+ Rules []Rule
- // DefaultTargets holds a target for each hook that will be executed if
- // chain traversal doesn't yield a verdict.
- DefaultTargets map[Hook]Target
+ // BuiltinChains maps builtin chains to their entrypoint rule in Rules.
+ BuiltinChains map[Hook]int
+
+ // Underflows maps builtin chains to their underflow rule in Rules
+ // (i.e. the rule to execute if the chain returns without a verdict).
+ Underflows map[Hook]int
// UserChains holds user-defined chains for the keyed by name. Users
// can give their chains arbitrary names.
- UserChains map[string]Chain
-
- // Chains maps names to chains for both builtin and user-defined chains.
- // Its entries point to Chains already either in BuiltinChains or
- // UserChains, and its purpose is to make looking up tables by name
- // fast.
- Chains map[string]*Chain
+ UserChains map[string]int
// Metadata holds information about the Table that is useful to users
// of IPTables, but not to the netstack IPTables code itself.
@@ -152,21 +148,6 @@ func (table *Table) SetMetadata(metadata interface{}) {
table.metadata = metadata
}
-// A Chain defines a list of rules for packet processing. When a packet
-// traverses a chain, it is checked against each rule until either a rule
-// returns a verdict or the chain ends.
-//
-// By convention, builtin chains end with a rule that matches everything and
-// returns either Accept or Drop. User-defined chains end with Return. These
-// aren't strictly necessary here, but the iptables tool writes tables this way.
-type Chain struct {
- // Name is the chain name.
- Name string
-
- // Rules is the list of rules to traverse.
- Rules []Rule
-}
-
// A Rule is a packet processing rule. It consists of two pieces. First it
// contains zero or more matchers, each of which is a specification of which
// packets this rule applies to. If there are no matchers in the rule, it
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-05 05:37:54 +0000