iptables: remove metadata struct

Metadata was useful for debugging and safety, but enough tests exist that we
should see failures when (de)serialization is broken. It made stack
initialization more cumbersome and it's also getting in the way of ip6tables.

PiperOrigin-RevId: 317210653

2 files changed, 1 insertions, 23 deletions

diff --git a/pkg/tcpip/stack/iptables.go b/pkg/tcpip/stack/iptables.go
index 4e9b404c8..dc2b77c9d 100644
--- a/pkg/tcpip/stack/iptables.go
+++ b/pkg/tcpip/stack/iptables.go
@@ -173,14 +173,6 @@ func (it *IPTables) ReplaceTable(name string, table Table) {
 	it.tables[name] = table
 }
 
-// ModifyTables acquires write-lock and calls fn with internal name-to-table
-// map. This function can be used to update multiple tables atomically.
-func (it *IPTables) ModifyTables(fn func(map[string]Table)) {
-	it.mu.Lock()
-	defer it.mu.Unlock()
-	fn(it.tables)
-}
-
 // GetPriorities returns slice of priorities associated with hook.
 func (it *IPTables) GetPriorities(hook Hook) []string {
 	it.mu.RLock()
diff --git a/pkg/tcpip/stack/iptables_types.go b/pkg/tcpip/stack/iptables_types.go
index 4a6a5c6f1..72f1dd329 100644
--- a/pkg/tcpip/stack/iptables_types.go
+++ b/pkg/tcpip/stack/iptables_types.go
@@ -95,7 +95,7 @@ type IPTables struct {
 }
 
 // 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.
+// really just a list of rules.
 type Table struct {
 	// Rules holds the rules that make up the table.
 	Rules []Rule
@@ -110,10 +110,6 @@ type Table struct {
 	// UserChains holds user-defined chains for the keyed by name. Users
 	// can give their chains arbitrary names.
 	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.
-	metadata interface{}
 }
 
 // ValidHooks returns a bitmap of the builtin hooks for the given table.
@@ -125,16 +121,6 @@ func (table *Table) ValidHooks() uint32 {
 	return hooks
 }
 
-// Metadata returns the metadata object stored in table.
-func (table *Table) Metadata() interface{} {
-	return table.metadata
-}
-
-// SetMetadata sets the metadata object stored in table.
-func (table *Table) SetMetadata(metadata interface{}) {
-	table.metadata = metadata
-}
-
 // 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