egressgw: Let the EGW manager relax rp_filter on egress device

[MitchLewis930]

User description

PR_047

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PR Type

Enhancement, Bug fix

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Description

• Relax rp_filter on egress interfaces to fix reply packet drops

• Add interface name tracking to gateway configuration

• Refactor netdevice functions to return interface names

• Add comprehensive rp_filter testing and validation

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Diagram Walkthrough

flowchart LR
  A["Policy Configuration"] -->|derives gateway config| B["Gateway Config"]
  B -->|tracks interface name| C["Interface Name"]
  C -->|used to relax| D["rp_filter Setting"]
  E["Manager Reconciliation"] -->|calls| F["relaxRPFilter"]
  F -->|applies sysctl| D
  G["Netdevice Functions"] -->|refactored to return| C

Loading

File Walkthrough

	Relevant files
Enhancement	netdevice.go Refactor netdevice functions to return interface names      pkg/datapath/linux/netdevice/netdevice.go Refactored TestForIfaceWithIPv4Address to extract private getIfaceWithIPv4Address function Added public GetIfaceWithIPv4Address function that returns interface name instead of just error Updated return types to include interface name for all three function variants +13/-4    manager.go Add rp_filter relaxation to egress gateway manager              pkg/egressgateway/manager.go Added sysctl field to Manager struct for system control operations Injected sysctl.Sysctl dependency through Params struct Implemented relaxRPFilter() method to set rp_filter to 2 on egress interfaces Integrated relaxRPFilter() call into reconciliation flow after gateway config regeneration +38/-0    policy.go Track interface name and gateway configuration status        pkg/egressgateway/policy.go Added ifaceName field to gatewayConfig struct to track interface name Added localNodeConfiguredAsGateway boolean flag to indicate local node gateway role Updated deriveFromPolicyGatewayConfig to populate interface name in all code paths Changed from TestForIfaceWithIPv4Address to GetIfaceWithIPv4Address to capture interface name +15/-2
Tests	manager_privileged_test.go Add rp_filter validation and testing infrastructure            pkg/egressgateway/manager_privileged_test.go Added rpFilterSetting struct to represent rp_filter test assertions Injected sysctl.Sysctl dependency into test suite and helper functions Implemented ensureRPFilterIsEnabled to verify rp_filter is set to 1 on test interfaces Added assertRPFilter and tryAssertRPFilterSettings functions to validate rp_filter values Updated createTestInterface to initialize rp_filter on test interfaces Added test assertion for rp_filter relaxation after policy addition +59/-4

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[qodo-code-review]

PR Compliance Guide 🔍

Below is a summary of compliance checks for this PR:

Security Compliance
⚪	Anti-spoofing weakened Description: The new relaxRPFilter() unconditionally sets net.ipv4.conf..rp_filter=2 for egress interfaces derived from policy config, which weakens kernel anti-spoofing protections and may also be abused to relax rp_filter on broader scopes (e.g., all/default) if a policy can influence ifaceName, potentially increasing exposure to source-address spoofing on the node. manager.go [602-627] Referred Code func (manager *Manager) relaxRPFilter() error { var sysSettings []tables.Sysctl ifSet := make(map[string]struct{}) for _, pc := range manager.policyConfigs { if !pc.gatewayConfig.localNodeConfiguredAsGateway { continue } ifaceName := pc.gatewayConfig.ifaceName if _, ok := ifSet[ifaceName]; !ok { ifSet[ifaceName] = struct{}{} sysSettings = append(sysSettings, tables.Sysctl{ Name: fmt.Sprintf("net.ipv4.conf.%s.rp_filter", ifaceName), Val: "2", IgnoreErr: false, }) } } if len(sysSettings) == 0 { ... (clipped 5 lines)
Ticket Compliance
⚪	🎫 No ticket provided Create ticket/issue
Codebase Duplication Compliance
⚪	Codebase context is not defined Follow the guide to enable codebase context checks.
Custom Compliance
🟢	Generic: Secure Error Handling Objective: To prevent the leakage of sensitive system information through error messages while providing sufficient detail for internal debugging. Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Secure Logging Practices Objective: To ensure logs are useful for debugging and auditing without exposing sensitive information like PII, PHI, or cardholder data. Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
🔴	Generic: Meaningful Naming and Self-Documenting Code Objective: Ensure all identifiers clearly express their purpose and intent, making code self-documenting Status: Non-idiomatic naming: The new test helper struct uses unclear and inconsistent identifiers (e.g., iFaceName and redundant rpFilterSetting.rpFilterSetting) which reduces readability and intent clarity. Referred Code type rpFilterSetting struct { iFaceName string rpFilterSetting string } Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Robust Error Handling and Edge Case Management Objective: Ensure comprehensive error handling that provides meaningful context and graceful degradation Status: Error dropped silently: When relaxRPFilter() fails during reconciliation, the code retries but does not log or otherwise surface the underlying error, making production debugging difficult. Referred Code if err := manager.relaxRPFilter(); err != nil { manager.reconciliationTrigger.TriggerWithReason("retry after error") return } Learn more about managing compliance generic rules or creating your own custom rules
⚪	Generic: Comprehensive Audit Trails Objective: To create a detailed and reliable record of critical system actions for security analysis and compliance. Status: Sysctl change unlogged: The PR changes kernel rp_filter sysctl settings without emitting any audit log event that would allow operators to reconstruct when/what was changed and whether it succeeded. Referred Code func (manager *Manager) relaxRPFilter() error { var sysSettings []tables.Sysctl ifSet := make(map[string]struct{}) for _, pc := range manager.policyConfigs { if !pc.gatewayConfig.localNodeConfiguredAsGateway { continue } ifaceName := pc.gatewayConfig.ifaceName if _, ok := ifSet[ifaceName]; !ok { ifSet[ifaceName] = struct{}{} sysSettings = append(sysSettings, tables.Sysctl{ Name: fmt.Sprintf("net.ipv4.conf.%s.rp_filter", ifaceName), Val: "2", IgnoreErr: false, }) } } if len(sysSettings) == 0 { ... (clipped 5 lines) Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Security-First Input Validation and Data Handling Objective: Ensure all data inputs are validated, sanitized, and handled securely to prevent vulnerabilities Status: Sysctl key injection: The sysctl name is constructed with fmt.Sprintf("net.ipv4.conf.%s.rp_filter", ifaceName) using ifaceName derived from policy/config without visible validation, which may allow unexpected sysctl targets depending on how sysctl.ApplySettings maps names to /proc/sys. Referred Code ifaceName := pc.gatewayConfig.ifaceName if _, ok := ifSet[ifaceName]; !ok { ifSet[ifaceName] = struct{}{} sysSettings = append(sysSettings, tables.Sysctl{ Name: fmt.Sprintf("net.ipv4.conf.%s.rp_filter", ifaceName), Val: "2", IgnoreErr: false, }) Learn more about managing compliance generic rules or creating your own custom rules

Compliance status legend

🟢 - Fully Compliant
🟡 - Partial Compliant
🔴 - Not Compliant
⚪ - Requires Further Human Verification
🏷️ - Compliance label

[qodo-code-review]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
High-level	Consider reverting rp_filter upon policy removal The current implementation modifies the rp_filter setting for egress interfaces but fails to revert it when the corresponding policy is removed. It is suggested to track and restore the original rp_filter value to avoid leaving the system in a modified state. Examples: pkg/egressgateway/manager.go [602-627] func (manager *Manager) relaxRPFilter() error { var sysSettings []tables.Sysctl ifSet := make(map[string]struct{}) for _, pc := range manager.policyConfigs { if !pc.gatewayConfig.localNodeConfiguredAsGateway { continue } ifaceName := pc.gatewayConfig.ifaceName ... (clipped 16 lines) Solution Walkthrough: Before: // pkg/egressgateway/manager.go func (manager *Manager) relaxRPFilter() error { var sysSettings []tables.Sysctl ifSet := make(map[string]struct{}) // Collect interfaces from currently active policies for _, pc := range manager.policyConfigs { // ... ifaceName := pc.gatewayConfig.ifaceName if _, ok := ifSet[ifaceName]; !ok { ifSet[ifaceName] = struct{}{} // Only sets rp_filter to 2 sysSettings = append(sysSettings, tables.Sysctl{ Name: fmt.Sprintf("net.ipv4.conf.%s.rp_filter", ifaceName), Val: "2", }) } } return manager.sysctl.ApplySettings(sysSettings) } After: // pkg/egressgateway/manager.go type Manager struct { // ... // Track interfaces that had rp_filter modified rpFilterRelaxedIfaces map[string]string // ifaceName -> original value } func (manager *Manager) reconcileRPFilter() error { activeIfaces := make(map[string]struct{}) // Collect interfaces from currently active policies for _, pc := range manager.policyConfigs { // ... activeIfaces[pc.gatewayConfig.ifaceName] = struct{}{} } // Relax rp_filter for active interfaces for iface := range activeIfaces { // ... read original value, store it, and set to "2" } // Revert rp_filter for interfaces no longer in use for iface, originalValue := range manager.rpFilterRelaxedIfaces { if _, ok := activeIfaces[iface]; !ok { // ... revert to originalValue and remove from manager.rpFilterRelaxedIfaces } } return nil } Suggestion importance[1-10]: 8 __ Why: The suggestion correctly identifies a design flaw where system-level rp_filter settings are modified but not reverted, leading to permanent configuration changes that should be ephemeral.	Medium
General	Use a polling utility for test stability Replace the manual retry loop and time.Sleep in ensureRPFilterIsEnabled with testutils.WaitUntil to create a more robust and less flaky test. pkg/egressgateway/manager_privileged_test.go [531-549] func ensureRPFilterIsEnabled(tb testing.TB, sysctl sysctl.Sysctl, iface string) { rpFilterSetting := fmt.Sprintf("net.ipv4.conf.%s.rp_filter", iface) - for i := 0; i < 10; i++ { + // There can be a delay between interface creation and the sysctl being available. + err := testutils.WaitUntil(func() bool { if err := sysctl.Enable(rpFilterSetting); err != nil { - tb.Fatal(err) + // This can fail if the sysctl file is not yet created by the kernel. + return false } + val, err := sysctl.Read(rpFilterSetting) + return err == nil && val == "1" + }, 5*time.Second) - time.Sleep(100 * time.Millisecond) - - if val, err := sysctl.Read(rpFilterSetting); err == nil { - if val == "1" { - return - } - } + if err != nil { + tb.Fatalf("Failed to enable rp_filter on %s: %v", iface, err) } - - tb.Fatal("failed to enable rp_filter") } Apply / Chat Suggestion importance[1-10]: 7 __ Why: The suggestion correctly points out that using a fixed sleep in a retry loop in tests is a bad practice. Replacing it with a polling utility like testutils.WaitUntil improves test robustness and reliability.	Medium
	Log error on rp_filter relaxation failure Log the error when manager.relaxRPFilter() fails before triggering a reconciliation retry to improve debuggability. pkg/egressgateway/manager.go [727-736] manager.regenerateGatewayConfigs() if err := manager.relaxRPFilter(); err != nil { - manager.reconciliationTrigger.TriggerWithReason("retry after error") + log.WithError(err).Warning("Failed to relax rp_filter, will retry reconciliation") + manager.reconciliationTrigger.TriggerWithReason("retry after rp_filter relaxation error") return } // The order of the next 2 function calls matters, as by first adding missing policies and [To ensure code accuracy, apply this suggestion manually] Suggestion importance[1-10]: 6 __ Why: The suggestion correctly identifies that an error from manager.relaxRPFilter() is not logged, which hinders debugging. Adding logging is a good practice for observability.	Low
	wrap sysctl ApplySettings error Wrap the error returned from manager.sysctl.ApplySettings in relaxRPFilter to provide more context on failure. pkg/egressgateway/manager.go [626] -return manager.sysctl.ApplySettings(sysSettings) +if err := manager.sysctl.ApplySettings(sysSettings); err != nil { + return fmt.Errorf("failed to apply rp_filter settings: %w", err) +} +return nil Apply / Chat Suggestion importance[1-10]: 6 __ Why: The suggestion correctly proposes to wrap the error returned by ApplySettings to provide more context, which is a good practice for error handling and makes debugging easier.	Low
	add context to rp_filter assertion errors Improve error messages in tryAssertRPFilterSettings to include the interface name, expected value, and actual value for better test failure diagnostics. pkg/egressgateway/manager_privileged_test.go [680-684] if val, err := sysctl.Read(fmt.Sprintf("net.ipv4.conf.%s.rp_filter", setting.iFaceName)); err != nil { - return fmt.Errorf("failed to read rp_filter") + return fmt.Errorf("failed to read rp_filter for iface %s: %v", setting.iFaceName, err) } else if val != setting.rpFilterSetting { - return fmt.Errorf("mismatched rp_filter iface: %s rp_filter: %s", setting.iFaceName, val) + return fmt.Errorf("expected rp_filter=%s on iface %s, got %s", setting.rpFilterSetting, setting.iFaceName, val) } Apply / Chat Suggestion importance[1-10]: 5 __ Why: This suggestion improves the error messages in a test helper function, making test failures easier to diagnose by providing more context.	Low
	clarify missing-interface error Improve the error message in getIfaceWithIPv4Address to more clearly state that no interface was found with the specified IPv4 address. pkg/datapath/linux/netdevice/netdevice.go [70] -return "", fmt.Errorf("no interface with %s IPv4 assigned to", ip) +return "", fmt.Errorf("no interface found with IPv4 address %s", ip) Apply / Chat Suggestion importance[1-10]: 4 __ Why: This is a minor but useful improvement to an error message, making it clearer and more grammatically correct, which can help with debugging.	Low
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