ossl_cmp_msg_check_update(): improve diagnostics of checking expected sender name

Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: David von Oheimb <david.von.oheimb@siemens.com>
(Merged from https://github.com/openssl/openssl/pull/19948)

3 files changed, 28 insertions, 15 deletions

diff --git a/crypto/cmp/cmp_err.c b/crypto/cmp/cmp_err.c
index 6c2588d4d4..30095aa7c5 100644
--- a/crypto/cmp/cmp_err.c
+++ b/crypto/cmp/cmp_err.c
@@ -152,6 +152,7 @@ static const ERR_STRING_DATA CMP_str_reasons[] = {
     "unexpected pkistatus"},
     {ERR_PACK(ERR_LIB_CMP, 0, CMP_R_UNEXPECTED_POLLREQ), "unexpected pollreq"},
     {ERR_PACK(ERR_LIB_CMP, 0, CMP_R_UNEXPECTED_PVNO), "unexpected pvno"},
+    {ERR_PACK(ERR_LIB_CMP, 0, CMP_R_UNEXPECTED_SENDER), "unexpected sender"},
     {ERR_PACK(ERR_LIB_CMP, 0, CMP_R_UNKNOWN_ALGORITHM_ID),
     "unknown algorithm id"},
     {ERR_PACK(ERR_LIB_CMP, 0, CMP_R_UNKNOWN_CERT_TYPE), "unknown cert type"},
diff --git a/crypto/cmp/cmp_vfy.c b/crypto/cmp/cmp_vfy.c
index 39fca416ee..5c5cd456dd 100644
--- a/crypto/cmp/cmp_vfy.c
+++ b/crypto/cmp/cmp_vfy.c
@@ -175,8 +175,8 @@ static int check_name(const OSSL_CMP_CTX *ctx, int log_success,
     str = X509_NAME_oneline(actual_name, NULL, 0);
     if (X509_NAME_cmp(actual_name, expect_name) == 0) {
         if (log_success && str != NULL)
-            ossl_cmp_log2(INFO, ctx, " subject matches %s: %s", expect_desc,
-                          str);
+            ossl_cmp_log3(INFO, ctx, " %s matches %s: %s",
+                          actual_desc, expect_desc, str);
         OPENSSL_free(str);
         return 1;
     }
@@ -711,22 +711,33 @@ int ossl_cmp_msg_check_update(OSSL_CMP_CTX *ctx, const OSSL_CMP_MSG *msg,
         return 0;
     hdr = OSSL_CMP_MSG_get0_header(msg);
 
-    /* validate sender name of received msg */
-    if (hdr->sender->type != GEN_DIRNAME) {
-        ERR_raise(ERR_LIB_CMP, CMP_R_SENDER_GENERALNAME_TYPE_NOT_SUPPORTED);
-        return 0;
-    }
-    /*
-     * Compare actual sender name of response with expected sender name.
-     * Mitigates risk to accept misused PBM secret
-     * or misused certificate of an unauthorized entity of a trusted hierarchy.
-     */
+    /* If expected_sender is given, validate sender name of received msg */
     expected_sender = ctx->expected_sender;
     if (expected_sender == NULL && ctx->srvCert != NULL)
         expected_sender = X509_get_subject_name(ctx->srvCert);
-    if (!check_name(ctx, 0, "sender DN field", hdr->sender->d.directoryName,
-                    "expected sender", expected_sender))
-        return 0;
+    if (expected_sender != NULL) {
+        const X509_NAME *actual_sender;
+        char *str;
+
+        if (hdr->sender->type != GEN_DIRNAME) {
+            ERR_raise(ERR_LIB_CMP, CMP_R_SENDER_GENERALNAME_TYPE_NOT_SUPPORTED);
+            return 0;
+        }
+        actual_sender = hdr->sender->d.directoryName;
+        /*
+         * Compare actual sender name of response with expected sender name.
+         * Mitigates risk of accepting misused PBM secret or
+         * misused certificate of an unauthorized entity of a trusted hierarchy.
+         */
+        if (!check_name(ctx, 0, "sender DN field", actual_sender,
+                        "expected sender", expected_sender)) {
+            str = X509_NAME_oneline(actual_sender, NULL, 0);
+            ERR_raise_data(ERR_LIB_CMP, CMP_R_UNEXPECTED_SENDER,
+                           str != NULL ? str : "<unknown>");
+            OPENSSL_free(str);
+            return 0;
+        }
+    }
     /* Note: if recipient was NULL-DN it could be learned here if needed */
 
     num_added = sk_X509_num(msg->extraCerts);
diff --git a/crypto/err/openssl.txt b/crypto/err/openssl.txt
index fd6b128a2a..b999ec3363 100644
--- a/crypto/err/openssl.txt
+++ b/crypto/err/openssl.txt
@@ -278,6 +278,7 @@ CMP_R_UNEXPECTED_PKIBODY:133:unexpected pkibody
 CMP_R_UNEXPECTED_PKISTATUS:185:unexpected pkistatus
 CMP_R_UNEXPECTED_POLLREQ:105:unexpected pollreq
 CMP_R_UNEXPECTED_PVNO:153:unexpected pvno
+CMP_R_UNEXPECTED_SENDER:104:unexpected sender
 CMP_R_UNKNOWN_ALGORITHM_ID:134:unknown algorithm id
 CMP_R_UNKNOWN_CERT_TYPE:135:unknown cert type
 CMP_R_UNKNOWN_PKISTATUS:186:unknown pkistatus