[PATCH] cmd/go: restrict meta imports to valid schemes

Before this change, when using -insecure, we permitted any meta import
repo root as long as it contained "://". When not using -insecure, we
restrict meta import repo roots to be valid URLs. People may depend on
that somehow, so permit meta import repo roots to be invalid URLs, but
require them to have valid schemes per RFC 3986.

Fixes #23867

Change-Id: Iac666dfc75ac321bf8639dda5b0dba7c8840922d
Reviewed-on: https://go-review.googlesource.com/94603
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Gbp-Pq: Name cve-2018-7187.patch

diff --git a/src/cmd/go/vcs.go b/src/cmd/go/vcs.go
index 53ddbe694eec327b9de156823aba2aa0e24a39d8..9cd46884ff4d7986e9e40676b597f0666b61f183 100644 (file)
--- a/src/cmd/go/vcs.go
+++ b/src/cmd/go/vcs.go
@@ -691,8 +691,8 @@ func repoRootForImportDynamic(importPath string, security securityMode) (*repoRo
                }
        }
 
-       if !strings.Contains(mmi.RepoRoot, "://") {
-               return nil, fmt.Errorf("%s: invalid repo root %q; no scheme", urlStr, mmi.RepoRoot)
+       if err := validateRepoRootScheme(mmi.RepoRoot); err != nil {
+               return nil, fmt.Errorf("%s: invalid repo root %q: %v", urlStr, mmi.RepoRoot, err)
        }
        rr := &repoRoot{
                vcs:  vcsByCmd(mmi.VCS),
@@ -705,6 +705,36 @@ func repoRootForImportDynamic(importPath string, security securityMode) (*repoRo
        return rr, nil
 }
 
+// validateRepoRootScheme returns an error if repoRoot does not seem
+// to have a valid URL scheme. At this point we permit things that
+// aren't valid URLs, although later, if not using -insecure, we will
+// restrict repoRoots to be valid URLs. This is only because we've
+// historically permitted them, and people may depend on that.
+func validateRepoRootScheme(repoRoot string) error {
+       end := strings.Index(repoRoot, "://")
+       if end <= 0 {
+               return errors.New("no scheme")
+       }
+
+       // RFC 3986 section 3.1.
+       for i := 0; i < end; i++ {
+               c := repoRoot[i]
+               switch {
+               case 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z':
+                       // OK.
+               case '0' <= c && c <= '9' || c == '+' || c == '-' || c == '.':
+                       // OK except at start.
+                       if i == 0 {
+                               return errors.New("invalid scheme")
+                       }
+               default:
+                       return errors.New("invalid scheme")
+               }
+       }
+
+       return nil
+}
+
 var fetchGroup singleflight.Group
 var (
        fetchCacheMu sync.Mutex

diff --git a/src/cmd/go/vcs_test.go b/src/cmd/go/vcs_test.go
index 25e3866df06d771e59139d40e09e97dde8ae0a90..f7a6a833fc372209881fcc48347b0363e6ae9f8f 100644 (file)
--- a/src/cmd/go/vcs_test.go
+++ b/src/cmd/go/vcs_test.go
@@ -321,3 +321,46 @@ func TestMatchGoImport(t *testing.T) {
                }
        }
 }
+
+func TestValidateRepoRootScheme(t *testing.T) {
+       tests := []struct {
+               root string
+               err  string
+       }{
+               {
+                       root: "",
+                       err:  "no scheme",
+               },
+               {
+                       root: "http://",
+                       err:  "",
+               },
+               {
+                       root: "a://",
+                       err:  "",
+               },
+               {
+                       root: "a#://",
+                       err:  "invalid scheme",
+               },
+               {
+                       root: "-config://",
+                       err:  "invalid scheme",
+               },
+       }
+
+       for _, test := range tests {
+               err := validateRepoRootScheme(test.root)
+               if err == nil {
+                       if test.err != "" {
+                               t.Errorf("validateRepoRootScheme(%q) = nil, want %q", test.root, test.err)
+                       }
+               } else if test.err == "" {
+                       if err != nil {
+                               t.Errorf("validateRepoRootScheme(%q) = %q, want nil", test.root, test.err)
+                       }
+               } else if err.Error() != test.err {
+                       t.Errorf("validateRepoRootScheme(%q) = %q, want %q", test.root, err, test.err)
+               }
+       }
+}