X509 validation fixes

src/internal.c

@@ -13542,6 +13542,57 @@ static int PatternHasWildcardInALabel(const char* pattern, word32 patternLen)
     return 0;
 }
 
+/* Validate the placement of a wildcard ('*') in a presented identifier per
+ * RFC 6125 sec. 6.4.3 / RFC 9525 sec. 6.3 and CA/Browser Forum Baseline
+ * Requirements sec. 3.2.2.6:
+ *   - a wildcard may only appear in the left-most label of the pattern, and
+ *   - a left-most label consisting solely of the wildcard ("*") may match only
+ *     when at least two further labels (i.e. at least two dots) follow it.
+ *
+ * This rejects a bare "*" (matches any single-label name), "*.com" (wildcard
+ * immediately to the left of a registry/public suffix), and
+ * "foo.*.example.com" (wildcard not in the left-most label), while still
+ * accepting the legitimate "*.example.com" form. Partial left-most wildcards
+ * such as "a*" or "a*b*" retain their existing matching behavior - they are
+ * not bare wildcard labels and are not subject to the two-label requirement.
+ * pattern/patternLen must already have any single trailing FQDN dot stripped.
+ *
+ * Returns 1 if the pattern has no wildcard or its wildcard placement is
+ * acceptable, 0 otherwise. */
+static int WildcardPlacementOK(const char* pattern, word32 patternLen)
+{
+    word32 i;
+    int sawWildcard = 0;
+    int sawDot = 0;
+    int dots = 0;
+
+    for (i = 0; i < patternLen; i++) {
+        if (pattern[i] == '*') {
+            /* A wildcard is only permitted in the left-most label: reject any
+             * '*' that appears after a label separator. */
+            if (sawDot)
+                return 0;
+            sawWildcard = 1;
+        }
+        else if (pattern[i] == '.') {
+            sawDot = 1;
+            dots++;
+        }
+    }
+
+    if (!sawWildcard)
+        return 1;
+
+    /* A left-most label that is exactly "*" (a bare wildcard label) requires at
+     * least two further labels. This rejects a bare "*" (0 dots) and "*.tld"
+     * (1 dot) but still allows "*.example.com" (2 dots). */
+    if (pattern[0] == '*' && (patternLen == 1 || pattern[1] == '.') &&
+            dots < 2)
+        return 0;
+
+    return 1;
+}
+
 /* Match names with wildcards, each wildcard can represent a single name
    component or fragment but not multiple names, i.e.,
    *.z.com matches y.z.com but not x.y.z.com
@@ -13598,6 +13649,13 @@ int MatchDomainName(const char* pattern, int patternLen, const char* str,
         }
     }
 
+    /* RFC 6125 sec. 6.4.3 / RFC 9525 sec. 6.3 + CA/Browser Forum BR
+     * sec. 3.2.2.6: reject a pattern whose wildcard is not confined to the
+     * left-most label, or that has fewer than two labels to the right of the
+     * wildcard (e.g. "*", "*.com", "foo.*.example.com"). */
+    if (!WildcardPlacementOK(pattern, (word32)patternLen))
+        return 0;
+
     while (patternLen > 0) {
         /* Get the next pattern char to evaluate */
         char p = (char)XTOLOWER((unsigned char)*pattern);

src/x509_str.c

@@ -629,6 +629,99 @@ static int X509StoreCertIsTrusted(WOLFSSL_X509_STORE* store,
     return 0;
 }
 
+/* Enforce the BasicConstraints pathLenConstraint (RFC 5280 sec. 4.2.1.9 and
+ * the path validation rules in sec. 6.1.4 (l)/(m)) over the certification path
+ * assembled in ctx->chain.
+ *
+ * wolfSSL_X509_verify_cert() authenticates each certificate individually via
+ * the CertManager, which parses every certificate as CERT_TYPE.  The issuer
+ * pathLen check in ParseCertRelative() is gated on a non-CERT_TYPE certificate
+ * type (it is reached on the TLS handshake path via CHAIN_CERT_TYPE), so the
+ * OpenSSL-compatibility path never enforced it.  Re-create that check here over
+ * the completed path so that a CA asserting pathlen:N cannot issue more than N
+ * subordinate intermediate CAs.
+ *
+ * ctx->chain is ordered leaf first (index 0) up to the trust anchor (highest
+ * index).  Walk from the trust anchor down toward the leaf, tracking the
+ * remaining number of non-self-issued intermediate certificates permitted.
+ * WOLFSSL_MAX_PATH_LEN is used as the "no constraint" sentinel, mirroring
+ * InitDecodedCert_ex()/ParseCertRelative().  The leaf (index 0) issues nothing
+ * and is therefore not subject to the constraint.
+ *
+ * Returns WOLFSSL_SUCCESS if the path satisfies every pathLenConstraint, or
+ * WOLFSSL_FAILURE (with ctx->error set) on the first violation. */
+static int X509StoreCheckPathLen(WOLFSSL_X509_STORE_CTX* ctx)
+{
+    int num;
+    int i;
+    word32 maxPathLen = WOLFSSL_MAX_PATH_LEN;
+    WOLFSSL_X509* anchor;
+
+    if (ctx == NULL || ctx->chain == NULL)
+        return WOLFSSL_SUCCESS;
+
+    num = wolfSSL_sk_X509_num(ctx->chain);
+    /* A pathLen violation requires at least one intermediate between the leaf
+     * (index 0) and the trust anchor, i.e. a chain of three or more. */
+    if (num < 3)
+        return WOLFSSL_SUCCESS;
+
+    /* The trust anchor (top of chain) is not part of the prospective
+     * certification path (RFC 5280 sec. 6.1): it does not consume path-length
+     * budget. A self-signed anchor that asserts its own pathLenConstraint does
+     * still bound the path, matching ParseCertRelative()'s trust-anchor
+     * handling, so seed the budget from it. The partial-chain branch of
+     * wolfSSL_X509_verify_cert() pushes the terminal certificate twice, so the
+     * anchor pointer can also appear at num-2; it is skipped by pointer below
+     * to avoid double-counting. */
+    anchor = wolfSSL_sk_X509_value(ctx->chain, num - 1);
+    if (anchor != NULL && anchor->isCa && anchor->basicConstPlSet)
+        maxPathLen = (word32)anchor->pathLength;
+
+    for (i = num - 2; i >= 1; i--) {
+        WOLFSSL_X509* cert = wolfSSL_sk_X509_value(ctx->chain, i);
+        int selfIssued;
+
+        if (cert == NULL || cert == anchor)
+            continue;
+
+        selfIssued =
+            (wolfSSL_X509_NAME_cmp(&cert->issuer, &cert->subject) == 0);
+
+        /* RFC 5280 sec. 6.1.4 (l): a non-self-issued certificate consumes one
+         * unit of the issuer's remaining path length budget. */
+        if (!selfIssued) {
+            if (maxPathLen == 0) {
+                SetupStoreCtxError_ex(ctx,
+                    WOLFSSL_X509_V_ERR_PATH_LENGTH_EXCEEDED, i);
+            #if defined(OPENSSL_ALL) || defined(WOLFSSL_QT)
+                /* Allow an application verify callback to override, matching
+                 * the INVALID_CA handling in wolfSSL_X509_verify_cert(). */
+                if (ctx->store != NULL && ctx->store->verify_cb != NULL &&
+                        ctx->store->verify_cb(0, ctx) == 1) {
+                    /* Overridden: keep walking without decrementing (budget is
+                     * already exhausted). */
+                    continue;
+                }
+            #endif
+                return WOLFSSL_FAILURE;
+            }
+            else if (maxPathLen != WOLFSSL_MAX_PATH_LEN) {
+                maxPathLen--;
+            }
+        }
+
+        /* RFC 5280 sec. 6.1.4 (m): tighten the budget with this CA's own
+         * pathLenConstraint, if present. */
+        if (cert->isCa && cert->basicConstPlSet &&
+                (word32)cert->pathLength < maxPathLen) {
+            maxPathLen = (word32)cert->pathLength;
+        }
+    }
+
+    return WOLFSSL_SUCCESS;
+}
+
 /* Verifies certificate chain using WOLFSSL_X509_STORE_CTX
  * returns 1 on success or <= 0 on failure.
  */
@@ -878,6 +971,13 @@ int wolfSSL_X509_verify_cert(WOLFSSL_X509_STORE_CTX* ctx)
         ret = WOLFSSL_FAILURE;
     }
 
+    /* RFC 5280 sec. 6.1.4: the per-certificate CertManager verification above
+     * does not enforce the issuer's BasicConstraints pathLenConstraint on this
+     * API path, so check it over the assembled path before reporting success. */
+    if (ret == WOLFSSL_SUCCESS) {
+        ret = X509StoreCheckPathLen(ctx);
+    }
+
 exit:
     /* Copy back failed certs. */
     numFailedCerts = wolfSSL_sk_X509_num(failedCerts);