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net: verify results from Lookup* are valid domain names

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For the methods LookupCNAME, LookupSRV, LookupMX, LookupNS, and
LookupAddr check that the returned domain names are in fact valid DNS
names using the existing isDomainName function.

Thanks to Philipp Jeitner and Haya Shulman from Fraunhofer SIT for
reporting this issue.

Fixes #46241
Fixes CVE-2021-33195

Change-Id: I47a4f58c031cb752f732e88bbdae7f819f0af4f3
Reviewed-on: https://go-review.googlesource.com/c/go/+/323131
Trust: Roland Shoemaker <roland@golang.org>
Run-TryBot: Roland Shoemaker <roland@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Katie Hockman <katie@golang.org>
This commit is contained in:
Roland Shoemaker 2021-05-27 10:40:06 -07:00
parent 8bf5bf5173
commit cdcd02842d
2 changed files with 255 additions and 13 deletions
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157
src/net/dnsclient_unix_test.go
View file

@ -1799,3 +1799,160 @@ func TestPTRandNonPTR(t *testing.T) {
t.Errorf("names = %q; want %q", names, want)
}
}
func TestCVE202133195(t *testing.T) {
fake := fakeDNSServer{
rh: func(n, _ string, q dnsmessage.Message, _ time.Time) (dnsmessage.Message, error) {
r := dnsmessage.Message{
Header: dnsmessage.Header{
ID: q.Header.ID,
Response: true,
RCode: dnsmessage.RCodeSuccess,
RecursionAvailable: true,
},
Questions: q.Questions,
}
switch q.Questions[0].Type {
case dnsmessage.TypeCNAME:
r.Answers = []dnsmessage.Resource{}
case dnsmessage.TypeA: // CNAME lookup uses a A/AAAA as a proxy
r.Answers = append(r.Answers,
dnsmessage.Resource{
Header: dnsmessage.ResourceHeader{
Name: dnsmessage.MustNewName("<html>.golang.org."),
Type: dnsmessage.TypeA,
Class: dnsmessage.ClassINET,
Length: 4,
},
Body: &dnsmessage.AResource{
A: TestAddr,
},
},
)
case dnsmessage.TypeSRV:
n := q.Questions[0].Name
if n.String() == "_hdr._tcp.golang.org." {
n = dnsmessage.MustNewName("<html>.golang.org.")
}
r.Answers = append(r.Answers,
dnsmessage.Resource{
Header: dnsmessage.ResourceHeader{
Name: n,
Type: dnsmessage.TypeSRV,
Class: dnsmessage.ClassINET,
Length: 4,
},
Body: &dnsmessage.SRVResource{
Target: dnsmessage.MustNewName("<html>.golang.org."),
},
},
)
case dnsmessage.TypeMX:
r.Answers = append(r.Answers,
dnsmessage.Resource{
Header: dnsmessage.ResourceHeader{
Name: dnsmessage.MustNewName("<html>.golang.org."),
Type: dnsmessage.TypeMX,
Class: dnsmessage.ClassINET,
Length: 4,
},
Body: &dnsmessage.MXResource{
MX: dnsmessage.MustNewName("<html>.golang.org."),
},
},
)
case dnsmessage.TypeNS:
r.Answers = append(r.Answers,
dnsmessage.Resource{
Header: dnsmessage.ResourceHeader{
Name: dnsmessage.MustNewName("<html>.golang.org."),
Type: dnsmessage.TypeNS,
Class: dnsmessage.ClassINET,
Length: 4,
},
Body: &dnsmessage.NSResource{
NS: dnsmessage.MustNewName("<html>.golang.org."),
},
},
)
case dnsmessage.TypePTR:
r.Answers = append(r.Answers,
dnsmessage.Resource{
Header: dnsmessage.ResourceHeader{
Name: dnsmessage.MustNewName("<html>.golang.org."),
Type: dnsmessage.TypePTR,
Class: dnsmessage.ClassINET,
Length: 4,
},
Body: &dnsmessage.PTRResource{
PTR: dnsmessage.MustNewName("<html>.golang.org."),
},
},
)
}
return r, nil
},
}
r := Resolver{PreferGo: true, Dial: fake.DialContext}
// Change the default resolver to match our manipulated resolver
originalDefault := DefaultResolver
DefaultResolver = &r
defer func() {
DefaultResolver = originalDefault
}()
_, err := r.LookupCNAME(context.Background(), "golang.org")
if expected := "lookup golang.org: CNAME target is invalid"; err == nil || err.Error() != expected {
t.Errorf("Resolver.LookupCNAME returned unexpected error, got %q, want %q", err.Error(), expected)
}
_, err = LookupCNAME("golang.org")
if expected := "lookup golang.org: CNAME target is invalid"; err == nil || err.Error() != expected {
t.Errorf("LookupCNAME returned unexpected error, got %q, want %q", err.Error(), expected)
}
_, _, err = r.LookupSRV(context.Background(), "target", "tcp", "golang.org")
if expected := "lookup golang.org: SRV target is invalid"; err == nil || err.Error() != expected {
t.Errorf("Resolver.LookupSRV returned unexpected error, got %q, want %q", err.Error(), expected)
}
_, _, err = LookupSRV("target", "tcp", "golang.org")
if expected := "lookup golang.org: SRV target is invalid"; err == nil || err.Error() != expected {
t.Errorf("LookupSRV returned unexpected error, got %q, want %q", err.Error(), expected)
}
_, _, err = r.LookupSRV(context.Background(), "hdr", "tcp", "golang.org")
if expected := "lookup golang.org: SRV header name is invalid"; err == nil || err.Error() != expected {
t.Errorf("Resolver.LookupSRV returned unexpected error, got %q, want %q", err.Error(), expected)
}
_, _, err = LookupSRV("hdr", "tcp", "golang.org")
if expected := "lookup golang.org: SRV header name is invalid"; err == nil || err.Error() != expected {
t.Errorf("LookupSRV returned unexpected error, got %q, want %q", err.Error(), expected)
}
_, err = r.LookupMX(context.Background(), "golang.org")
if expected := "lookup golang.org: MX target is invalid"; err == nil || err.Error() != expected {
t.Errorf("Resolver.LookupMX returned unexpected error, got %q, want %q", err.Error(), expected)
}
_, err = LookupMX("golang.org")
if expected := "lookup golang.org: MX target is invalid"; err == nil || err.Error() != expected {
t.Errorf("LookupMX returned unexpected error, got %q, want %q", err.Error(), expected)
}
_, err = r.LookupNS(context.Background(), "golang.org")
if expected := "lookup golang.org: NS target is invalid"; err == nil || err.Error() != expected {
t.Errorf("Resolver.LookupNS returned unexpected error, got %q, want %q", err.Error(), expected)
}
_, err = LookupNS("golang.org")
if expected := "lookup golang.org: NS target is invalid"; err == nil || err.Error() != expected {
t.Errorf("LookupNS returned unexpected error, got %q, want %q", err.Error(), expected)
}
_, err = r.LookupAddr(context.Background(), "1.2.3.4")
if expected := "lookup 1.2.3.4: PTR target is invalid"; err == nil || err.Error() != expected {
t.Errorf("Resolver.LookupAddr returned unexpected error, got %q, want %q", err.Error(), expected)
}
_, err = LookupAddr("1.2.3.4")
if expected := "lookup 1.2.3.4: PTR target is invalid"; err == nil || err.Error() != expected {
t.Errorf("LookupAddr returned unexpected error, got %q, want %q", err.Error(), expected)
}
}