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From 5d3b28deac44c19e4d73fc80e4917d42ee43adfe Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
Date: Wed, 2 Dec 2020 23:01:11 +0100
Subject: [PATCH] openssl: make the OCSP verification verify the certificate id
CVE-2020-8286
Reported by anonymous
Bug: https://curl.se/docs/CVE-2020-8286.html
Upstream-Status: Backport [https://github.com/curl/curl/commit/d9d01672785b]
CVE: CVE-2020-8286
Signed-off-by: Daniel Stenberg <daniel@haxx.se>
Signed-off-by: Khairul Rohaizzat Jamaluddin <khairul.rohaizzat.jamaluddin@intel.com>
---
lib/vtls/openssl.c | 83 +++++++++++++++++++++++++++++++++++-------------------
1 file changed, 54 insertions(+), 29 deletions(-)
diff --git a/lib/vtls/openssl.c b/lib/vtls/openssl.c
index 1685a4a..22cbfe7 100644
--- a/lib/vtls/openssl.c
+++ b/lib/vtls/openssl.c
@@ -1777,6 +1777,11 @@ static CURLcode verifystatus(struct connectdata *conn,
X509_STORE *st = NULL;
STACK_OF(X509) *ch = NULL;
struct ssl_backend_data *backend = connssl->backend;
+ X509 *cert;
+ OCSP_CERTID *id = NULL;
+ int cert_status, crl_reason;
+ ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
+ int ret;
long len = SSL_get_tlsext_status_ocsp_resp(backend->handle, &status);
@@ -1845,43 +1850,63 @@ static CURLcode verifystatus(struct connectdata *conn,
goto end;
}
- for(i = 0; i < OCSP_resp_count(br); i++) {
- int cert_status, crl_reason;
- OCSP_SINGLERESP *single = NULL;
-
- ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
+ /* Compute the certificate's ID */
+ cert = SSL_get_peer_certificate(backend->handle);
+ if(!cert) {
+ failf(data, "Error getting peer certficate");
+ result = CURLE_SSL_INVALIDCERTSTATUS;
+ goto end;
+ }
- single = OCSP_resp_get0(br, i);
- if(!single)
- continue;
+ for(i = 0; i < sk_X509_num(ch); i++) {
+ X509 *issuer = sk_X509_value(ch, i);
+ if(X509_check_issued(issuer, cert) == X509_V_OK) {
+ id = OCSP_cert_to_id(EVP_sha1(), cert, issuer);
+ break;
+ }
+ }
+ X509_free(cert);
- cert_status = OCSP_single_get0_status(single, &crl_reason, &rev,
- &thisupd, &nextupd);
+ if(!id) {
+ failf(data, "Error computing OCSP ID");
+ result = CURLE_SSL_INVALIDCERTSTATUS;
+ goto end;
+ }
- if(!OCSP_check_validity(thisupd, nextupd, 300L, -1L)) {
- failf(data, "OCSP response has expired");
- result = CURLE_SSL_INVALIDCERTSTATUS;
- goto end;
- }
+ /* Find the single OCSP response corresponding to the certificate ID */
+ ret = OCSP_resp_find_status(br, id, &cert_status, &crl_reason, &rev,
+ &thisupd, &nextupd);
+ OCSP_CERTID_free(id);
+ if(ret != 1) {
+ failf(data, "Could not find certificate ID in OCSP response");
+ result = CURLE_SSL_INVALIDCERTSTATUS;
+ goto end;
+ }
- infof(data, "SSL certificate status: %s (%d)\n",
- OCSP_cert_status_str(cert_status), cert_status);
+ /* Validate the corresponding single OCSP response */
+ if(!OCSP_check_validity(thisupd, nextupd, 300L, -1L)) {
+ failf(data, "OCSP response has expired");
+ result = CURLE_SSL_INVALIDCERTSTATUS;
+ goto end;
+ }
- switch(cert_status) {
- case V_OCSP_CERTSTATUS_GOOD:
- break;
+ infof(data, "SSL certificate status: %s (%d)\n",
+ OCSP_cert_status_str(cert_status), cert_status);
- case V_OCSP_CERTSTATUS_REVOKED:
- result = CURLE_SSL_INVALIDCERTSTATUS;
+ switch(cert_status) {
+ case V_OCSP_CERTSTATUS_GOOD:
+ break;
- failf(data, "SSL certificate revocation reason: %s (%d)",
- OCSP_crl_reason_str(crl_reason), crl_reason);
- goto end;
+ case V_OCSP_CERTSTATUS_REVOKED:
+ result = CURLE_SSL_INVALIDCERTSTATUS;
+ failf(data, "SSL certificate revocation reason: %s (%d)",
+ OCSP_crl_reason_str(crl_reason), crl_reason);
+ goto end;
- case V_OCSP_CERTSTATUS_UNKNOWN:
- result = CURLE_SSL_INVALIDCERTSTATUS;
- goto end;
- }
+ case V_OCSP_CERTSTATUS_UNKNOWN:
+ default:
+ result = CURLE_SSL_INVALIDCERTSTATUS;
+ goto end;
}
end:
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