connector/saml: make unparsable (trailing, non-space/newline) data an error

Fixes #1304, if we want to be harsh.

However, I think if it was the user's intention to pass two certs, and
the second one couldn't be read, that shouldn't just disappear. After
all, when attempting to login later, that might fail because the
expected IdP cert data isn't there.
Signed-off-by: Stephan Renatus <srenatus@chef.io>

connector/saml/saml.go

@@ -2,6 +2,7 @@
 package saml
 
 import (
+	"bytes"
 	"crypto/x509"
 	"encoding/base64"
 	"encoding/pem"
@@ -200,6 +201,10 @@ func (c *Config) openConnector(logger logrus.FieldLogger) (*provider, error) {
 		for {
 			block, caData = pem.Decode(caData)
 			if block == nil {
+				caData = bytes.TrimSpace(caData)
+				if len(caData) > 0 { // if there's some left, we've been given bad caData
+					return nil, fmt.Errorf("parse cert: trailing data: %q", string(caData))
+				}
 				break
 			}
 			cert, err := x509.ParseCertificate(block.Bytes)

connector/saml/saml_test.go

@@ -337,6 +337,93 @@ func (r responseTest) run(t *testing.T) {
 	}
 }
 
+func TestConfigCAData(t *testing.T) {
+	logger := logrus.New()
+	validPEM, err := ioutil.ReadFile("testdata/ca.crt")
+	if err != nil {
+		t.Fatal(err)
+	}
+	valid2ndPEM, err := ioutil.ReadFile("testdata/okta-ca.pem")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// copy helper, avoid messing with the byte slice among different cases
+	c := func(bs []byte) []byte {
+		return append([]byte(nil), bs...)
+	}
+
+	tests := []struct {
+		name    string
+		caData  []byte
+		wantErr bool
+	}{
+		{
+			name:   "one valid PEM entry",
+			caData: c(validPEM),
+		},
+		{
+			name:   "one valid PEM entry with trailing newline",
+			caData: append(c(validPEM), []byte("\n")...),
+		},
+		{
+			name:   "one valid PEM entry with trailing spaces",
+			caData: append(c(validPEM), []byte("   ")...),
+		},
+		{
+			name:   "one valid PEM entry with two trailing newlines",
+			caData: append(c(validPEM), []byte("\n\n")...),
+		},
+		{
+			name:   "two valid PEM entries",
+			caData: append(c(validPEM), c(valid2ndPEM)...),
+		},
+		{
+			name:   "two valid PEM entries with newline in between",
+			caData: append(append(c(validPEM), []byte("\n")...), c(valid2ndPEM)...),
+		},
+		{
+			name:   "two valid PEM entries with trailing newline",
+			caData: append(c(valid2ndPEM), append(c(validPEM), []byte("\n")...)...),
+		},
+		{
+			name:    "empty",
+			caData:  []byte{},
+			wantErr: true,
+		},
+		{
+			name:    "one valid PEM entry with trailing data",
+			caData:  append(c(validPEM), []byte("yaddayadda")...),
+			wantErr: true,
+		},
+		{
+			name:    "one valid PEM entry with bad data before",
+			caData:  append([]byte("yaddayadda"), c(validPEM)...),
+			wantErr: true,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			c := Config{
+				CAData:       tc.caData,
+				UsernameAttr: "user",
+				EmailAttr:    "email",
+				RedirectURI:  "http://127.0.0.1:5556/dex/callback",
+				SSOURL:       "http://foo.bar/",
+			}
+			_, err := (&c).Open("samltest", logger)
+			if tc.wantErr {
+				if err == nil {
+					t.Error("expected error, got nil")
+				}
+			} else if err != nil {
+				t.Errorf("expected no error, got %v", err)
+			}
+		})
+	}
+}
+
 const (
 	defaultSSOIssuer   = "http://www.okta.com/exk91cb99lKkKSYoy0h7"
 	defaultRedirectURI = "http://localhost:5556/dex/callback"