From 31d60cda1f58b7558fc5725d2b9e4531655d980e Mon Sep 17 00:00:00 2001 From: Roland Shoemaker Date: Thu, 27 May 2021 10:40:06 -0700 Subject: [release-branch.go1.15] net: verify results from Lookup* are valid domain names 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. Updates #46241 Fixes #46356 Fixes CVE-2021-33195 Change-Id: I47a4f58c031cb752f732e88bbdae7f819f0af4f3 Reviewed-on: https://go-review.googlesource.com/c/go/+/323131 Trust: Roland Shoemaker Run-TryBot: Roland Shoemaker TryBot-Result: Go Bot Reviewed-by: Filippo Valsorda Reviewed-by: Katie Hockman (cherry picked from commit cdcd02842da7c004efd023881e3719105209c908) Reviewed-on: https://go-review.googlesource.com/c/go/+/323269 --- src/net/dnsclient_unix_test.go | 157 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 157 insertions(+) (limited to 'src/net/dnsclient_unix_test.go') diff --git a/src/net/dnsclient_unix_test.go b/src/net/dnsclient_unix_test.go index 06553636ee..819f20b887 100644 --- a/src/net/dnsclient_unix_test.go +++ b/src/net/dnsclient_unix_test.go @@ -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(".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(".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(".golang.org."), + }, + }, + ) + case dnsmessage.TypeMX: + r.Answers = append(r.Answers, + dnsmessage.Resource{ + Header: dnsmessage.ResourceHeader{ + Name: dnsmessage.MustNewName(".golang.org."), + Type: dnsmessage.TypeMX, + Class: dnsmessage.ClassINET, + Length: 4, + }, + Body: &dnsmessage.MXResource{ + MX: dnsmessage.MustNewName(".golang.org."), + }, + }, + ) + case dnsmessage.TypeNS: + r.Answers = append(r.Answers, + dnsmessage.Resource{ + Header: dnsmessage.ResourceHeader{ + Name: dnsmessage.MustNewName(".golang.org."), + Type: dnsmessage.TypeNS, + Class: dnsmessage.ClassINET, + Length: 4, + }, + Body: &dnsmessage.NSResource{ + NS: dnsmessage.MustNewName(".golang.org."), + }, + }, + ) + case dnsmessage.TypePTR: + r.Answers = append(r.Answers, + dnsmessage.Resource{ + Header: dnsmessage.ResourceHeader{ + Name: dnsmessage.MustNewName(".golang.org."), + Type: dnsmessage.TypePTR, + Class: dnsmessage.ClassINET, + Length: 4, + }, + Body: &dnsmessage.PTRResource{ + PTR: dnsmessage.MustNewName(".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) + } +} -- cgit v1.2.3-54-g00ecf