--- /dev/null
+From 9324d7e53151e9dfa4b25af994a28c2e0b11f729 Mon Sep 17 00:00:00 2001
+From: Roland Shoemaker <roland@golang.org>
+Date: Thu, 27 May 2021 10:40:06 -0700
+Subject: [PATCH] net: verify results from Lookup* are valid domain names
+
+Upstream-Status: Backport [https://github.com/golang/go/commit/31d60cda1f58b7558fc5725d2b9e4531655d980e]
+CVE: CVE-2021-33195
+Signed-off-by: Ralph Siemsen <ralph.siemsen@linaro.org>
+
+
+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 <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>
+(cherry picked from commit cdcd02842da7c004efd023881e3719105209c908)
+Reviewed-on: https://go-review.googlesource.com/c/go/+/323269
+---
+ src/net/dnsclient_unix_test.go | 157 +++++++++++++++++++++++++++++++++
+ src/net/lookup.go | 111 ++++++++++++++++++++---
+ 2 files changed, 255 insertions(+), 13 deletions(-)
+
+diff --git a/src/net/dnsclient_unix_test.go b/src/net/dnsclient_unix_test.go
+index 2ad40df..b8617d9 100644
+--- a/src/net/dnsclient_unix_test.go
++++ b/src/net/dnsclient_unix_test.go
+@@ -1800,3 +1800,160 @@ 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)
++ }
++}
+diff --git a/src/net/lookup.go b/src/net/lookup.go
+index 9cebd10..05e88e4 100644
+--- a/src/net/lookup.go
++++ b/src/net/lookup.go
+@@ -364,8 +364,11 @@ func (r *Resolver) LookupPort(ctx context.Context, network, service string) (por
+ // LookupCNAME does not return an error if host does not
+ // contain DNS "CNAME" records, as long as host resolves to
+ // address records.
++//
++// The returned canonical name is validated to be a properly
++// formatted presentation-format domain name.
+ func LookupCNAME(host string) (cname string, err error) {
+- return DefaultResolver.lookupCNAME(context.Background(), host)
++ return DefaultResolver.LookupCNAME(context.Background(), host)
+ }
+
+ // LookupCNAME returns the canonical name for the given host.
+@@ -378,8 +381,18 @@ func LookupCNAME(host string) (cname string, err error) {
+ // LookupCNAME does not return an error if host does not
+ // contain DNS "CNAME" records, as long as host resolves to
+ // address records.
+-func (r *Resolver) LookupCNAME(ctx context.Context, host string) (cname string, err error) {
+- return r.lookupCNAME(ctx, host)
++//
++// The returned canonical name is validated to be a properly
++// formatted presentation-format domain name.
++func (r *Resolver) LookupCNAME(ctx context.Context, host string) (string, error) {
++ cname, err := r.lookupCNAME(ctx, host)
++ if err != nil {
++ return "", err
++ }
++ if !isDomainName(cname) {
++ return "", &DNSError{Err: "CNAME target is invalid", Name: host}
++ }
++ return cname, nil
+ }
+
+ // LookupSRV tries to resolve an SRV query of the given service,
+@@ -391,8 +404,11 @@ func (r *Resolver) LookupCNAME(ctx context.Context, host string) (cname string,
+ // That is, it looks up _service._proto.name. To accommodate services
+ // publishing SRV records under non-standard names, if both service
+ // and proto are empty strings, LookupSRV looks up name directly.
++//
++// The returned service names are validated to be properly
++// formatted presentation-format domain names.
+ func LookupSRV(service, proto, name string) (cname string, addrs []*SRV, err error) {
+- return DefaultResolver.lookupSRV(context.Background(), service, proto, name)
++ return DefaultResolver.LookupSRV(context.Background(), service, proto, name)
+ }
+
+ // LookupSRV tries to resolve an SRV query of the given service,
+@@ -404,28 +420,82 @@ func LookupSRV(service, proto, name string) (cname string, addrs []*SRV, err err
+ // That is, it looks up _service._proto.name. To accommodate services
+ // publishing SRV records under non-standard names, if both service
+ // and proto are empty strings, LookupSRV looks up name directly.
+-func (r *Resolver) LookupSRV(ctx context.Context, service, proto, name string) (cname string, addrs []*SRV, err error) {
+- return r.lookupSRV(ctx, service, proto, name)
++//
++// The returned service names are validated to be properly
++// formatted presentation-format domain names.
++func (r *Resolver) LookupSRV(ctx context.Context, service, proto, name string) (string, []*SRV, error) {
++ cname, addrs, err := r.lookupSRV(ctx, service, proto, name)
++ if err != nil {
++ return "", nil, err
++ }
++ if cname != "" && !isDomainName(cname) {
++ return "", nil, &DNSError{Err: "SRV header name is invalid", Name: name}
++ }
++ for _, addr := range addrs {
++ if addr == nil {
++ continue
++ }
++ if !isDomainName(addr.Target) {
++ return "", nil, &DNSError{Err: "SRV target is invalid", Name: name}
++ }
++ }
++ return cname, addrs, nil
+ }
+
+ // LookupMX returns the DNS MX records for the given domain name sorted by preference.
++//
++// The returned mail server names are validated to be properly
++// formatted presentation-format domain names.
+ func LookupMX(name string) ([]*MX, error) {
+- return DefaultResolver.lookupMX(context.Background(), name)
++ return DefaultResolver.LookupMX(context.Background(), name)
+ }
+
+ // LookupMX returns the DNS MX records for the given domain name sorted by preference.
++//
++// The returned mail server names are validated to be properly
++// formatted presentation-format domain names.
+ func (r *Resolver) LookupMX(ctx context.Context, name string) ([]*MX, error) {
+- return r.lookupMX(ctx, name)
++ records, err := r.lookupMX(ctx, name)
++ if err != nil {
++ return nil, err
++ }
++ for _, mx := range records {
++ if mx == nil {
++ continue
++ }
++ if !isDomainName(mx.Host) {
++ return nil, &DNSError{Err: "MX target is invalid", Name: name}
++ }
++ }
++ return records, nil
+ }
+
+ // LookupNS returns the DNS NS records for the given domain name.
++//
++// The returned name server names are validated to be properly
++// formatted presentation-format domain names.
+ func LookupNS(name string) ([]*NS, error) {
+- return DefaultResolver.lookupNS(context.Background(), name)
++ return DefaultResolver.LookupNS(context.Background(), name)
+ }
+
+ // LookupNS returns the DNS NS records for the given domain name.
++//
++// The returned name server names are validated to be properly
++// formatted presentation-format domain names.
+ func (r *Resolver) LookupNS(ctx context.Context, name string) ([]*NS, error) {
+- return r.lookupNS(ctx, name)
++ records, err := r.lookupNS(ctx, name)
++ if err != nil {
++ return nil, err
++ }
++ for _, ns := range records {
++ if ns == nil {
++ continue
++ }
++ if !isDomainName(ns.Host) {
++ return nil, &DNSError{Err: "NS target is invalid", Name: name}
++ }
++ }
++ return records, nil
+ }
+
+ // LookupTXT returns the DNS TXT records for the given domain name.
+@@ -441,14 +511,29 @@ func (r *Resolver) LookupTXT(ctx context.Context, name string) ([]string, error)
+ // LookupAddr performs a reverse lookup for the given address, returning a list
+ // of names mapping to that address.
+ //
++// The returned names are validated to be properly formatted presentation-format
++// domain names.
++//
+ // When using the host C library resolver, at most one result will be
+ // returned. To bypass the host resolver, use a custom Resolver.
+ func LookupAddr(addr string) (names []string, err error) {
+- return DefaultResolver.lookupAddr(context.Background(), addr)
++ return DefaultResolver.LookupAddr(context.Background(), addr)
+ }
+
+ // LookupAddr performs a reverse lookup for the given address, returning a list
+ // of names mapping to that address.
+-func (r *Resolver) LookupAddr(ctx context.Context, addr string) (names []string, err error) {
+- return r.lookupAddr(ctx, addr)
++//
++// The returned names are validated to be properly formatted presentation-format
++// domain names.
++func (r *Resolver) LookupAddr(ctx context.Context, addr string) ([]string, error) {
++ names, err := r.lookupAddr(ctx, addr)
++ if err != nil {
++ return nil, err
++ }
++ for _, name := range names {
++ if !isDomainName(name) {
++ return nil, &DNSError{Err: "PTR target is invalid", Name: addr}
++ }
++ }
++ return names, nil
+ }
projects / thirdparty / openembedded / openembedded-core.git / commitdiff
