chunk 7 of CMP contribution to OpenSSL

add CMP message validation and related tests; while doing so:
* add ERR_add_error_mem_bio() to crypto/err/err_prn.c
* move ossl_cmp_add_error_txt() as ERR_add_error_txt() to crypto/err/err_prn.c
* add X509_STORE_CTX_print_verify_cb() to crypto/x509/t_x509.c,
  adding internally x509_print_ex_brief(), print_certs(), and print_store_certs()
* move {ossl_cmp_,}X509_STORE_get1_certs() to crypto/x509/x509_lu.c

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/10620)

3 files changed, 142 insertions, 0 deletions

diff --git a/crypto/x509/t_x509.c b/crypto/x509/t_x509.c
index 4969bb34bf..eac299c09a 100644
--- a/crypto/x509/t_x509.c
+++ b/crypto/x509/t_x509.c
@@ -15,6 +15,7 @@
 #include <openssl/x509.h>
 #include <openssl/x509v3.h>
 #include "crypto/asn1.h"
+#include "crypto/x509.h"
 
 #ifndef OPENSSL_NO_STDIO
 int X509_print_fp(FILE *fp, X509 *x)
@@ -380,3 +381,107 @@ int X509_aux_print(BIO *out, X509 *x, int indent)
     }
     return 1;
 }
+
+/*
+ * Helper functions for improving certificate verification error diagnostics
+ */
+
+int x509_print_ex_brief(BIO *bio, X509 *cert, unsigned long neg_cflags)
+{
+    unsigned long flags = ASN1_STRFLGS_RFC2253 | ASN1_STRFLGS_ESC_QUOTE |
+        XN_FLAG_SEP_CPLUS_SPC | XN_FLAG_FN_SN;
+
+    if (cert == NULL)
+        return BIO_printf(bio, "    (no certificate)\n") > 0;
+    if (BIO_printf(bio, "    certificate\n") <= 0
+            || !X509_print_ex(bio, cert, flags, ~X509_FLAG_NO_SUBJECT))
+        return 0;
+    if (X509_check_issued((X509 *)cert, cert) == X509_V_OK) {
+        if (BIO_printf(bio, "        self-issued\n") <= 0)
+            return 0;
+    } else {
+        if (BIO_printf(bio, " ") <= 0
+            || !X509_print_ex(bio, cert, flags, ~X509_FLAG_NO_ISSUER))
+            return 0;
+    }
+    if (!X509_print_ex(bio, cert, flags,
+                       ~(X509_FLAG_NO_SERIAL | X509_FLAG_NO_VALIDITY)))
+        return 0;
+    if (X509_cmp_current_time(X509_get0_notBefore(cert)) > 0)
+        if (BIO_printf(bio, "        not yet valid\n") <= 0)
+            return 0;
+    if (X509_cmp_current_time(X509_get0_notAfter(cert)) < 0)
+        if (BIO_printf(bio, "        no more valid\n") <= 0)
+            return 0;
+    return X509_print_ex(bio, cert, flags, ~(neg_cflags));
+}
+
+static int print_certs(BIO *bio, const STACK_OF(X509) *certs)
+{
+    int i;
+
+    if (certs == NULL || sk_X509_num(certs) <= 0)
+        return BIO_printf(bio, "    (no certificates)\n") >= 0;
+
+    for (i = 0; i < sk_X509_num(certs); i++) {
+        X509 *cert = sk_X509_value(certs, i);
+        if (cert != NULL && !x509_print_ex_brief(bio, cert, 0))
+            return 0;
+    }
+    return 1;
+}
+
+static int print_store_certs(BIO *bio, X509_STORE *store)
+{
+    if (store != NULL) {
+        STACK_OF(X509) *certs = X509_STORE_get1_all_certs(store);
+        int ret = print_certs(bio, certs);
+
+        sk_X509_pop_free(certs, X509_free);
+        return ret;
+    } else {
+        return BIO_printf(bio, "    (no trusted store)\n") >= 0;
+    }
+}
+
+/* Extend the error queue with details on a failed cert verification */
+int X509_STORE_CTX_print_verify_cb(int ok, X509_STORE_CTX *ctx)
+{
+    if (ok == 0 && ctx != NULL) {
+        int cert_error = X509_STORE_CTX_get_error(ctx);
+        int depth = X509_STORE_CTX_get_error_depth(ctx);
+        X509 *cert = X509_STORE_CTX_get_current_cert(ctx);
+        BIO *bio = BIO_new(BIO_s_mem()); /* may be NULL */
+
+        BIO_printf(bio, "%s at depth=%d error=%d (%s)\n",
+                   X509_STORE_CTX_get0_parent_ctx(ctx) != NULL
+                   ? "CRL path validation" : "certificate verification",
+                   depth, cert_error,
+                   X509_verify_cert_error_string(cert_error));
+        BIO_printf(bio, "failure for:\n");
+        x509_print_ex_brief(bio, cert, X509_FLAG_NO_EXTENSIONS);
+        if (cert_error == X509_V_ERR_CERT_UNTRUSTED
+                || cert_error == X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT
+                || cert_error == X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN
+                || cert_error == X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT
+                || cert_error == X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY
+                || cert_error == X509_V_ERR_UNABLE_TO_GET_CRL_ISSUER
+                || cert_error == X509_V_ERR_STORE_LOOKUP) {
+            BIO_printf(bio, "non-trusted certs:\n");
+            print_certs(bio, X509_STORE_CTX_get0_untrusted(ctx));
+            BIO_printf(bio, "certs in trust store:\n");
+            print_store_certs(bio, X509_STORE_CTX_get0_store(ctx));
+        }
+        CMPerr(0, X509_R_CERTIFICATE_VERIFICATION_FAILED);
+        ERR_add_error_mem_bio("\n", bio);
+        BIO_free(bio);
+    }
+
+    /*
+     * TODO we could check policies here too, e.g.:
+     * if (cert_error == X509_V_OK && ok == 2)
+     *     policies_print(NULL, ctx);
+     */
+
+    return ok;
+}
diff --git a/crypto/x509/x509_err.c b/crypto/x509/x509_err.c
index 1b01fd0131..59ffbee6d8 100644
--- a/crypto/x509/x509_err.c
+++ b/crypto/x509/x509_err.c
@@ -22,6 +22,8 @@ static const ERR_STRING_DATA X509_str_reasons[] = {
     {ERR_PACK(ERR_LIB_X509, 0, X509_R_CANT_CHECK_DH_KEY), "cant check dh key"},
     {ERR_PACK(ERR_LIB_X509, 0, X509_R_CERT_ALREADY_IN_HASH_TABLE),
     "cert already in hash table"},
+    {ERR_PACK(ERR_LIB_X509, 0, X509_R_CERTIFICATE_VERIFICATION_FAILED),
+    "certificate verification failed"},
     {ERR_PACK(ERR_LIB_X509, 0, X509_R_CRL_ALREADY_DELTA), "crl already delta"},
     {ERR_PACK(ERR_LIB_X509, 0, X509_R_CRL_VERIFY_FAILURE),
     "crl verify failure"},
diff --git a/crypto/x509/x509_lu.c b/crypto/x509/x509_lu.c
index 016b4b304f..9018d6e114 100644
--- a/crypto/x509/x509_lu.c
+++ b/crypto/x509/x509_lu.c
@@ -532,6 +532,41 @@ STACK_OF(X509_OBJECT) *X509_STORE_get0_objects(X509_STORE *v)
     return v->objs;
 }
 
+STACK_OF(X509) *X509_STORE_get1_all_certs(X509_STORE *store)
+{
+    STACK_OF(X509) *sk;
+    STACK_OF(X509_OBJECT) *objs;
+    int i;
+
+    if (store == NULL) {
+        X509err(0, ERR_R_PASSED_NULL_PARAMETER);
+        return NULL;
+    }
+    if ((sk = sk_X509_new_null()) == NULL)
+        return NULL;
+    X509_STORE_lock(store);
+    objs = X509_STORE_get0_objects(store);
+    for (i = 0; i < sk_X509_OBJECT_num(objs); i++) {
+        X509 *cert = X509_OBJECT_get0_X509(sk_X509_OBJECT_value(objs, i));
+
+        if (cert != NULL) {
+            if (!X509_up_ref(cert))
+                goto err;
+            if (!sk_X509_push(sk, cert)) {
+                X509_free(cert);
+                goto err;
+            }
+        }
+    }
+    X509_STORE_unlock(store);
+    return sk;
+
+ err:
+    X509_STORE_unlock(store);
+    sk_X509_pop_free(sk, X509_free);
+    return NULL;
+}
+
 STACK_OF(X509) *X509_STORE_CTX_get1_certs(X509_STORE_CTX *ctx, X509_NAME *nm)
 {
     int i, idx, cnt;