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fix various problems with iptables.Exists

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This modifies iptables.Exists so that it must be called with an explicit
table and chain.  This allows us (a) to generate an appropriate command
line for "iptables -C", which was not previously possible, and (b) it
allows us to limit our strings.Contains() search to just the table and
chain in question, preventing erroneous matches against unrelated rules.

Resolves #10781

Signed-off-by: Lars Kellogg-Stedman <lars@redhat.com>
This commit is contained in:
Lars Kellogg-Stedman 2015-02-13 22:10:14 -05:00
parent aa11bf993a
commit ef50a94a9c
2 changed files with 35 additions and 34 deletions
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29
iptables/iptables.go
View file

@ -21,6 +21,7 @@ const (
Insert Action = "-I"
Nat Table = "nat"
Filter Table = "filter"
Mangle Table = "mangle"
)
var (
@ -82,7 +83,7 @@ func NewChain(name, bridge string, table Table) (*Chain, error) {
preroute := []string{
"-m", "addrtype",
"--dst-type", "LOCAL"}
if !Exists(preroute...) {
if !Exists(Nat, "PREROUTING", preroute...) {
if err := c.Prerouting(Append, preroute...); err != nil {
return nil, fmt.Errorf("Failed to inject docker in PREROUTING chain: %s", err)
}
@ -91,17 +92,17 @@ func NewChain(name, bridge string, table Table) (*Chain, error) {
"-m", "addrtype",
"--dst-type", "LOCAL",
"!", "--dst", "127.0.0.0/8"}
if !Exists(output...) {
if !Exists(Nat, "OUTPUT", output...) {
if err := c.Output(Append, output...); err != nil {
return nil, fmt.Errorf("Failed to inject docker in OUTPUT chain: %s", err)
}
}
case Filter:
link := []string{"FORWARD",
link := []string{
"-o", c.Bridge,
"-j", c.Name}
if !Exists(link...) {
insert := append([]string{string(Insert)}, link...)
if !Exists(Filter, "FORWARD", link...) {
insert := append([]string{string(Insert), "FORWARD"}, link...)
if output, err := Raw(insert...); err != nil {
return nil, err
} else if len(output) != 0 {
@ -242,19 +243,25 @@ func (c *Chain) Remove() error {
}
// Check if a rule exists
func Exists(args ...string) bool {
func Exists(table Table, chain string, rule ...string) bool {
if string(table) == "" {
table = Filter
}
// iptables -C, --check option was added in v.1.4.11
// http://ftp.netfilter.org/pub/iptables/changes-iptables-1.4.11.txt
// try -C
// if exit status is 0 then return true, the rule exists
if _, err := Raw(append([]string{"-C"}, args...)...); err == nil {
if _, err := Raw(append([]string{
"-t", string(table), "-C", chain}, rule...)...); err == nil {
return true
}
// parse iptables-save for the rule
rule := strings.Replace(strings.Join(args, " "), "-t nat ", "", -1)
existingRules, _ := exec.Command("iptables-save").Output()
// parse "iptables -S" for the rule (this checks rules in a specific chain
// in a specific table)
rule_string := strings.Join(rule, " ")
existingRules, _ := exec.Command("iptables", "-t", string(table), "-S", chain).Output()
// regex to replace ips in rule
// because MASQUERADE rule will not be exactly what was passed
@ -262,7 +269,7 @@ func Exists(args ...string) bool {
return strings.Contains(
re.ReplaceAllString(string(existingRules), "?"),
re.ReplaceAllString(rule, "?"),
re.ReplaceAllString(rule_string, "?"),
)
}

40
iptables/iptables_test.go
View file

@ -39,8 +39,7 @@ func TestForward(t *testing.T) {
t.Fatal(err)
}
dnatRule := []string{natChain.Name,
"-t", string(natChain.Table),
dnatRule := []string{
"!", "-i", filterChain.Bridge,
"-d", ip.String(),
"-p", proto,
@ -49,12 +48,11 @@ func TestForward(t *testing.T) {
"--to-destination", dstAddr + ":" + strconv.Itoa(dstPort),
}
if !Exists(dnatRule...) {
if !Exists(natChain.Table, natChain.Name, dnatRule...) {
t.Fatalf("DNAT rule does not exist")
}
filterRule := []string{filterChain.Name,
"-t", string(filterChain.Table),
filterRule := []string{
"!", "-i", filterChain.Bridge,
"-o", filterChain.Bridge,
"-d", dstAddr,
@ -63,12 +61,11 @@ func TestForward(t *testing.T) {
"-j", "ACCEPT",
}
if !Exists(filterRule...) {
if !Exists(filterChain.Table, filterChain.Name, filterRule...) {
t.Fatalf("filter rule does not exist")
}
masqRule := []string{"POSTROUTING",
"-t", string(natChain.Table),
masqRule := []string{
"-d", dstAddr,
"-s", dstAddr,
"-p", proto,
@ -76,7 +73,7 @@ func TestForward(t *testing.T) {
"-j", "MASQUERADE",
}
if !Exists(masqRule...) {
if !Exists(natChain.Table, "POSTROUTING", masqRule...) {
t.Fatalf("MASQUERADE rule does not exist")
}
}
@ -94,8 +91,7 @@ func TestLink(t *testing.T) {
t.Fatal(err)
}
rule1 := []string{filterChain.Name,
"-t", string(filterChain.Table),
rule1 := []string{
"-i", filterChain.Bridge,
"-o", filterChain.Bridge,
"-p", proto,
@ -104,12 +100,11 @@ func TestLink(t *testing.T) {
"--dport", strconv.Itoa(port),
"-j", "ACCEPT"}
if !Exists(rule1...) {
if !Exists(filterChain.Table, filterChain.Name, rule1...) {
t.Fatalf("rule1 does not exist")
}
rule2 := []string{filterChain.Name,
"-t", string(filterChain.Table),
rule2 := []string{
"-i", filterChain.Bridge,
"-o", filterChain.Bridge,
"-p", proto,
@ -118,7 +113,7 @@ func TestLink(t *testing.T) {
"--sport", strconv.Itoa(port),
"-j", "ACCEPT"}
if !Exists(rule2...) {
if !Exists(filterChain.Table, filterChain.Name, rule2...) {
t.Fatalf("rule2 does not exist")
}
}
@ -133,17 +128,16 @@ func TestPrerouting(t *testing.T) {
t.Fatal(err)
}
rule := []string{"PREROUTING",
"-t", string(Nat),
rule := []string{
"-j", natChain.Name}
rule = append(rule, args...)
if !Exists(rule...) {
if !Exists(natChain.Table, "PREROUTING", rule...) {
t.Fatalf("rule does not exist")
}
delRule := append([]string{"-D"}, rule...)
delRule := append([]string{"-D", "PREROUTING", "-t", string(Nat)}, rule...)
if _, err = Raw(delRule...); err != nil {
t.Fatal(err)
}
@ -159,17 +153,17 @@ func TestOutput(t *testing.T) {
t.Fatal(err)
}
rule := []string{"OUTPUT",
"-t", string(natChain.Table),
rule := []string{
"-j", natChain.Name}
rule = append(rule, args...)
if !Exists(rule...) {
if !Exists(natChain.Table, "OUTPUT", rule...) {
t.Fatalf("rule does not exist")
}
delRule := append([]string{"-D"}, rule...)
delRule := append([]string{"-D", "OUTPUT", "-t",
string(natChain.Table)}, rule...)
if _, err = Raw(delRule...); err != nil {
t.Fatal(err)
}