From 0999ae8b34d83a4b2ea8342d0459c8131c35d6e1 Mon Sep 17 00:00:00 2001
From: Kevin Krakauer <krakauer@google.com>
Date: Wed, 8 Jan 2020 15:57:25 -0800
Subject: Getting a panic when running tests. For some reason the filter table
 is ending up with the wrong chains and is indexing -1 into rules.

---
 pkg/sentry/socket/netfilter/netfilter.go | 17 ++++++-----------
 pkg/sentry/socket/netstack/netstack.go   | 12 ++++++++++--
 2 files changed, 16 insertions(+), 13 deletions(-)

(limited to 'pkg/sentry/socket')

diff --git a/pkg/sentry/socket/netfilter/netfilter.go b/pkg/sentry/socket/netfilter/netfilter.go
index 57785220e..3a857ef6d 100644
--- a/pkg/sentry/socket/netfilter/netfilter.go
+++ b/pkg/sentry/socket/netfilter/netfilter.go
@@ -25,7 +25,6 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
 	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserr"
-	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/iptables"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
 )
@@ -45,7 +44,7 @@ type metadata struct {
 }
 
 // GetInfo returns information about iptables.
-func GetInfo(t *kernel.Task, ep tcpip.Endpoint, outPtr usermem.Addr) (linux.IPTGetinfo, *syserr.Error) {
+func GetInfo(t *kernel.Task, stack *stack.Stack, outPtr usermem.Addr) (linux.IPTGetinfo, *syserr.Error) {
 	// Read in the struct and table name.
 	var info linux.IPTGetinfo
 	if _, err := t.CopyIn(outPtr, &info); err != nil {
@@ -53,7 +52,7 @@ func GetInfo(t *kernel.Task, ep tcpip.Endpoint, outPtr usermem.Addr) (linux.IPTG
 	}
 
 	// Find the appropriate table.
-	table, err := findTable(ep, info.Name.String())
+	table, err := findTable(stack, info.Name.String())
 	if err != nil {
 		return linux.IPTGetinfo{}, err
 	}
@@ -76,7 +75,7 @@ func GetInfo(t *kernel.Task, ep tcpip.Endpoint, outPtr usermem.Addr) (linux.IPTG
 }
 
 // GetEntries returns netstack's iptables rules encoded for the iptables tool.
-func GetEntries(t *kernel.Task, ep tcpip.Endpoint, outPtr usermem.Addr, outLen int) (linux.KernelIPTGetEntries, *syserr.Error) {
+func GetEntries(t *kernel.Task, stack *stack.Stack, outPtr usermem.Addr, outLen int) (linux.KernelIPTGetEntries, *syserr.Error) {
 	// Read in the struct and table name.
 	var userEntries linux.IPTGetEntries
 	if _, err := t.CopyIn(outPtr, &userEntries); err != nil {
@@ -84,7 +83,7 @@ func GetEntries(t *kernel.Task, ep tcpip.Endpoint, outPtr usermem.Addr, outLen i
 	}
 
 	// Find the appropriate table.
-	table, err := findTable(ep, userEntries.Name.String())
+	table, err := findTable(stack, userEntries.Name.String())
 	if err != nil {
 		return linux.KernelIPTGetEntries{}, err
 	}
@@ -103,12 +102,8 @@ func GetEntries(t *kernel.Task, ep tcpip.Endpoint, outPtr usermem.Addr, outLen i
 	return entries, nil
 }
 
-func findTable(ep tcpip.Endpoint, tableName string) (iptables.Table, *syserr.Error) {
-	ipt, err := ep.IPTables()
-	if err != nil {
-		return iptables.Table{}, syserr.FromError(err)
-	}
-	table, ok := ipt.Tables[tableName]
+func findTable(stack *stack.Stack, tableName string) (iptables.Table, *syserr.Error) {
+	table, ok := stack.IPTables().Tables[tableName]
 	if !ok {
 		return iptables.Table{}, syserr.ErrInvalidArgument
 	}
diff --git a/pkg/sentry/socket/netstack/netstack.go b/pkg/sentry/socket/netstack/netstack.go
index 8c07eef4b..86a8104df 100644
--- a/pkg/sentry/socket/netstack/netstack.go
+++ b/pkg/sentry/socket/netstack/netstack.go
@@ -826,7 +826,11 @@ func (s *SocketOperations) GetSockOpt(t *kernel.Task, level, name int, outPtr us
 				return nil, syserr.ErrInvalidArgument
 			}
 
-			info, err := netfilter.GetInfo(t, s.Endpoint, outPtr)
+			stack := inet.StackFromContext(t)
+			if stack == nil {
+				return nil, syserr.ErrNoDevice
+			}
+			info, err := netfilter.GetInfo(t, stack.(*Stack).Stack, outPtr)
 			if err != nil {
 				return nil, err
 			}
@@ -837,7 +841,11 @@ func (s *SocketOperations) GetSockOpt(t *kernel.Task, level, name int, outPtr us
 				return nil, syserr.ErrInvalidArgument
 			}
 
-			entries, err := netfilter.GetEntries(t, s.Endpoint, outPtr, outLen)
+			stack := inet.StackFromContext(t)
+			if stack == nil {
+				return nil, syserr.ErrNoDevice
+			}
+			entries, err := netfilter.GetEntries(t, stack.(*Stack).Stack, outPtr, outLen)
 			if err != nil {
 				return nil, err
 			}
-- 
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