Add -rsigopt option to ocsp command

Add a -rsigopt option to the ocsp command that allows signature parameters to be provided for the signing of OCSP responses. The parameters that may be provided to -rsigopt are the same as may be provided to -sigopt in the ca, req, and x509 commands.

This PR also defines a OCSP_basic_sign_ctx() function, which functions in the same way as OCSP_basic_sign(), except that it accepts a EVP_MD_CTX rather than a key and digest. The OCSP_basic_sign_ctx() function is used to implement the -rsigopt option in the ocsp command.

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4190)

3 files changed, 28 insertions, 5 deletions

diff --git a/crypto/ocsp/ocsp_err.c b/crypto/ocsp/ocsp_err.c
index 5faeff23c9..a97177e958 100644
--- a/crypto/ocsp/ocsp_err.c
+++ b/crypto/ocsp/ocsp_err.c
@@ -18,6 +18,7 @@ static const ERR_STRING_DATA OCSP_str_functs[] = {
     {ERR_PACK(ERR_LIB_OCSP, OCSP_F_OCSP_BASIC_ADD1_STATUS, 0),
      "OCSP_basic_add1_status"},
     {ERR_PACK(ERR_LIB_OCSP, OCSP_F_OCSP_BASIC_SIGN, 0), "OCSP_basic_sign"},
+    {ERR_PACK(ERR_LIB_OCSP, OCSP_F_OCSP_BASIC_SIGN_CTX, 0), "OCSP_basic_sign_ctx"},
     {ERR_PACK(ERR_LIB_OCSP, OCSP_F_OCSP_BASIC_VERIFY, 0), "OCSP_basic_verify"},
     {ERR_PACK(ERR_LIB_OCSP, OCSP_F_OCSP_CERT_ID_NEW, 0), "OCSP_cert_id_new"},
     {ERR_PACK(ERR_LIB_OCSP, OCSP_F_OCSP_CHECK_DELEGATED, 0),
diff --git a/crypto/ocsp/ocsp_lcl.h b/crypto/ocsp/ocsp_lcl.h
index d1cf1583f4..2215a0091d 100644
--- a/crypto/ocsp/ocsp_lcl.h
+++ b/crypto/ocsp/ocsp_lcl.h
@@ -224,6 +224,10 @@ struct ocsp_service_locator_st {
         ASN1_item_sign(ASN1_ITEM_rptr(OCSP_RESPDATA),&(o)->signatureAlgorithm,\
                 NULL,(o)->signature,&(o)->tbsResponseData,pkey,md)
 
+#  define OCSP_BASICRESP_sign_ctx(o,ctx,d) \
+        ASN1_item_sign_ctx(ASN1_ITEM_rptr(OCSP_RESPDATA),&(o)->signatureAlgorithm,\
+                NULL,(o)->signature,&(o)->tbsResponseData,ctx)
+
 #  define OCSP_REQUEST_verify(a,r) ASN1_item_verify(ASN1_ITEM_rptr(OCSP_REQINFO),\
         &(a)->optionalSignature->signatureAlgorithm,\
         (a)->optionalSignature->signature,&(a)->tbsRequest,r)
diff --git a/crypto/ocsp/ocsp_srv.c b/crypto/ocsp/ocsp_srv.c
index 51b27bddff..d31a3c0c25 100644
--- a/crypto/ocsp/ocsp_srv.c
+++ b/crypto/ocsp/ocsp_srv.c
@@ -168,15 +168,16 @@ int OCSP_basic_add1_cert(OCSP_BASICRESP *resp, X509 *cert)
     return 1;
 }
 
-int OCSP_basic_sign(OCSP_BASICRESP *brsp,
-                    X509 *signer, EVP_PKEY *key, const EVP_MD *dgst,
+int OCSP_basic_sign_ctx(OCSP_BASICRESP *brsp,
+                    X509 *signer, EVP_MD_CTX *ctx,
                     STACK_OF(X509) *certs, unsigned long flags)
 {
     int i;
     OCSP_RESPID *rid;
 
-    if (!X509_check_private_key(signer, key)) {
-        OCSPerr(OCSP_F_OCSP_BASIC_SIGN,
+    if (!ctx || !EVP_MD_CTX_pkey_ctx(ctx) || !EVP_PKEY_CTX_get0_pkey(EVP_MD_CTX_pkey_ctx(ctx)) ||
+        !X509_check_private_key(signer, EVP_PKEY_CTX_get0_pkey(EVP_MD_CTX_pkey_ctx(ctx)))) {
+        OCSPerr(OCSP_F_OCSP_BASIC_SIGN_CTX,
                 OCSP_R_PRIVATE_KEY_DOES_NOT_MATCH_CERTIFICATE);
         goto err;
     }
@@ -208,7 +209,7 @@ int OCSP_basic_sign(OCSP_BASICRESP *brsp,
      * -- Richard Levitte
      */
 
-    if (!OCSP_BASICRESP_sign(brsp, key, dgst, 0))
+    if (!OCSP_BASICRESP_sign_ctx(brsp, ctx, 0))
         goto err;
 
     return 1;
@@ -216,6 +217,23 @@ int OCSP_basic_sign(OCSP_BASICRESP *brsp,
     return 0;
 }
 
+int OCSP_basic_sign(OCSP_BASICRESP *brsp,
+                    X509 *signer, EVP_PKEY *key, const EVP_MD *dgst,
+                    STACK_OF(X509) *certs, unsigned long flags)
+{
+    EVP_MD_CTX *ctx = EVP_MD_CTX_new();
+    EVP_PKEY_CTX *pkctx = NULL;
+    int i;
+
+    if (!EVP_DigestSignInit(ctx, &pkctx, dgst, NULL, key)) {
+        EVP_MD_CTX_free(ctx);
+        return 1;
+    }
+    i = OCSP_basic_sign_ctx(brsp, signer, ctx, certs, flags);
+    EVP_MD_CTX_free(ctx);
+    return i;
+}
+
 int OCSP_RESPID_set_by_name(OCSP_RESPID *respid, X509 *cert)
 {
     if (!X509_NAME_set(&respid->value.byName, X509_get_subject_name(cert)))