*/
private FormValidation verifySignature(JSONObject o) throws IOException {
try {
FormValidation warning = null;
JSONObject signature = o.getJSONObject("signature");
if (signature.isNullObject()) {
return FormValidation.error("No signature block found in update center '"+id+"'");
}
o.remove("signature");
List<X509Certificate> certs = new ArrayList<X509Certificate>();
{// load and verify certificates
CertificateFactory cf = CertificateFactory.getInstance("X509");
for (Object cert : signature.getJSONArray("certificates")) {
X509Certificate c = (X509Certificate) cf.generateCertificate(new ByteArrayInputStream(Base64.decode(cert.toString().toCharArray())));
try {
c.checkValidity();
} catch (CertificateExpiredException e) { // even if the certificate isn't valid yet, we'll proceed it anyway
warning = FormValidation.warning(e,String.format("Certificate %s has expired in update center '%s'",cert.toString(),id));
} catch (CertificateNotYetValidException e) {
warning = FormValidation.warning(e,String.format("Certificate %s is not yet valid in update center '%s'",cert.toString(),id));
}
certs.add(c);
}
// if we trust default root CAs, we end up trusting anyone who has a valid certificate,
// which isn't useful at all
Set<TrustAnchor> anchors = new HashSet<TrustAnchor>(); // CertificateUtil.getDefaultRootCAs();
Jenkins j = Jenkins.getInstance();
for (String cert : (Set<String>) j.servletContext.getResourcePaths("/WEB-INF/update-center-rootCAs")) {
if (cert.endsWith(".txt")) continue; // skip text files that are meant to be documentation
anchors.add(new TrustAnchor((X509Certificate)cf.generateCertificate(j.servletContext.getResourceAsStream(cert)),null));
}
File[] cas = new File(j.root, "update-center-rootCAs").listFiles();
if (cas!=null) {
for (File cert : cas) {
if (cert.getName().endsWith(".txt")) continue; // skip text files that are meant to be documentation
FileInputStream in = new FileInputStream(cert);
try {
anchors.add(new TrustAnchor((X509Certificate)cf.generateCertificate(in),null));
} finally {
in.close();
}
}
}
CertificateUtil.validatePath(certs,anchors);
}
// this is for computing a digest to check sanity
MessageDigest sha1 = MessageDigest.getInstance("SHA1");
DigestOutputStream dos = new DigestOutputStream(new NullOutputStream(),sha1);
// this is for computing a signature
Signature sig = Signature.getInstance("SHA1withRSA");
sig.initVerify(certs.get(0));
SignatureOutputStream sos = new SignatureOutputStream(sig);
// until JENKINS-11110 fix, UC used to serve invalid digest (and therefore unverifiable signature)
// that only covers the earlier portion of the file. This was caused by the lack of close() call
// in the canonical writing, which apparently leave some bytes somewhere that's not flushed to
// the digest output stream. This affects Jenkins [1.424,1,431].
// Jenkins 1.432 shipped with the "fix" (1eb0c64abb3794edce29cbb1de50c93fa03a8229) that made it
// compute the correct digest, but it breaks all the existing UC json metadata out there. We then
// quickly discovered ourselves in the catch-22 situation. If we generate UC with the correct signature,
// it'll cut off [1.424,1.431] from the UC. But if we don't, we'll cut off [1.432,*).
//
// In 1.433, we revisited 1eb0c64abb3794edce29cbb1de50c93fa03a8229 so that the original "digest"/"signature"
// pair continues to be generated in a buggy form, while "correct_digest"/"correct_signature" are generated
// correctly.
//
// Jenkins should ignore "digest"/"signature" pair. Accepting it creates a vulnerability that allows
// the attacker to inject a fragment at the end of the json.
o.writeCanonical(new OutputStreamWriter(new TeeOutputStream(dos,sos),"UTF-8")).close();
// did the digest match? this is not a part of the signature validation, but if we have a bug in the c14n
// (which is more likely than someone tampering with update center), we can tell
String computedDigest = new String(Base64.encode(sha1.digest()));
String providedDigest = signature.optString("correct_digest");
if (providedDigest==null) {
return FormValidation.error("No correct_digest parameter in update center '"+id+"'. This metadata appears to be old.");
}
if (!computedDigest.equalsIgnoreCase(providedDigest)) {
return FormValidation.error("Digest mismatch: "+computedDigest+" vs "+providedDigest+" in update center '"+id+"'");
}
String providedSignature = signature.getString("correct_signature");
if (!sig.verify(Base64.decode(providedSignature.toCharArray()))) {
return FormValidation.error("Signature in the update center doesn't match with the certificate in update center '"+id+"'");
}
if (warning!=null) return warning;