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-rw-r--r--pkg/tcpip/iptables/iptables.go120
-rw-r--r--pkg/tcpip/iptables/targets.go16
-rw-r--r--pkg/tcpip/iptables/types.go49
3 files changed, 114 insertions, 71 deletions
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 2024-12-12 15:56:28 +0000