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networking: refactor some iptables for testability (#23856)
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,102 @@ | ||
| // Copyright (c) HashiCorp, Inc. | ||
| // SPDX-License-Identifier: BUSL-1.1 | ||
|
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| //go:build linux | ||
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| package allocrunner | ||
|
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| import ( | ||
| "fmt" | ||
|
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| "github.com/coreos/go-iptables/iptables" | ||
| "github.com/hashicorp/nomad/nomad/structs" | ||
| ) | ||
|
|
||
| const ( | ||
| // cniAdminChainName is the name of the admin iptables chain used to allow | ||
| // forwarding traffic to allocations | ||
| cniAdminChainName = "NOMAD-ADMIN" | ||
| ) | ||
|
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| // newIPTables provides an *iptables.IPTables for the requested address family | ||
| // "ipv6" or "ipv4" | ||
| func newIPTables(family structs.NodeNetworkAF) (IPTables, error) { | ||
| if family == structs.NodeNetworkAF_IPv6 { | ||
| return iptables.New(iptables.IPFamily(iptables.ProtocolIPv6), iptables.Timeout(5)) | ||
| } | ||
| return iptables.New() | ||
| } | ||
| func newIPTablesCleanup(family structs.NodeNetworkAF) (IPTablesCleanup, error) { | ||
| return newIPTables(family) | ||
| } | ||
| func newIPTablesChain(family structs.NodeNetworkAF) (IPTablesChain, error) { | ||
| return newIPTables(family) | ||
| } | ||
|
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| // IPTables is a subset of iptables.IPTables | ||
| type IPTables interface { | ||
| IPTablesCleanup | ||
| IPTablesChain | ||
| } | ||
| type IPTablesCleanup interface { | ||
| List(table, chain string) ([]string, error) | ||
| Delete(table, chain string, rule ...string) error | ||
| ClearAndDeleteChain(table, chain string) error | ||
| } | ||
| type IPTablesChain interface { | ||
| ListChains(table string) ([]string, error) | ||
| NewChain(table string, chain string) error | ||
| Exists(table string, chain string, rulespec ...string) (bool, error) | ||
| Append(table string, chain string, rulespec ...string) error | ||
| } | ||
|
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| // ensureChainRule ensures our admin chain exists and contains a rule to accept | ||
| // traffic to the bridge network | ||
| func ensureChainRule(ipt IPTablesChain, bridgeName, subnet string) error { | ||
| if err := ensureChain(ipt, "filter", cniAdminChainName); err != nil { | ||
| return err | ||
| } | ||
| rule := generateAdminChainRule(bridgeName, subnet) | ||
| if err := appendChainRule(ipt, cniAdminChainName, rule); err != nil { | ||
| return err | ||
| } | ||
| return nil | ||
| } | ||
|
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| // ensureChain ensures that the given chain exists, creating it if missing | ||
| func ensureChain(ipt IPTablesChain, table, chain string) error { | ||
| chains, err := ipt.ListChains(table) | ||
| if err != nil { | ||
| return fmt.Errorf("failed to list iptables chains: %v", err) | ||
| } | ||
| for _, ch := range chains { | ||
| if ch == chain { | ||
| return nil | ||
| } | ||
| } | ||
|
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| err = ipt.NewChain(table, chain) | ||
|
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| // if err is for chain already existing return as it is possible another | ||
| // goroutine created it first | ||
| if e, ok := err.(*iptables.Error); ok && e.ExitStatus() == 1 { | ||
| return nil | ||
| } | ||
|
|
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| return err | ||
| } | ||
|
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| // appendChainRule adds the given rule to the chain | ||
| func appendChainRule(ipt IPTablesChain, chain string, rule []string) error { | ||
| exists, err := ipt.Exists("filter", chain, rule...) | ||
| if !exists && err == nil { | ||
| err = ipt.Append("filter", chain, rule...) | ||
| } | ||
| return err | ||
| } | ||
|
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| // generateAdminChainRule builds the iptables rule that is inserted into the | ||
| // CNI admin chain to ensure traffic forwarding to the bridge network | ||
| func generateAdminChainRule(bridgeName, subnet string) []string { | ||
| return []string{"-o", bridgeName, "-d", subnet, "-j", "ACCEPT"} | ||
| } |
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