Check DSA parameters for excessive sizes before validating

This avoids overly long computation of various validation
checks.

Fixes CVE-2024-4603

Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from #24346)

(cherry picked from commit 85ccbab)

Author: t8m

CHANGES.md

@@ -27,6 +27,23 @@ OpenSSL 3.2
 
 ### Changes between 3.2.1 and 3.2.2 [xx XXX xxxx]
 
+ * Fixed an issue where checking excessively long DSA keys or parameters may
+   be very slow.
+
+   Applications that use the functions EVP_PKEY_param_check() or
+   EVP_PKEY_public_check() to check a DSA public key or DSA parameters may
+   experience long delays. Where the key or parameters that are being checked
+   have been obtained from an untrusted source this may lead to a Denial of
+   Service.
+
+   To resolve this issue DSA keys larger than OPENSSL_DSA_MAX_MODULUS_BITS
+   will now fail the check immediately with a DSA_R_MODULUS_TOO_LARGE error
+   reason.
+
+   ([CVE-2024-4603])
+
+   *Tomáš Mráz*
+
  * Fixed an issue where some non-default TLS server configurations can cause
    unbounded memory growth when processing TLSv1.3 sessions. An attacker may
    exploit certain server configurations to trigger unbounded memory growth that

crypto/dsa/dsa_check.c

@@ -19,8 +19,34 @@
 #include "dsa_local.h"
 #include "crypto/dsa.h"
 
+static int dsa_precheck_params(const DSA *dsa, int *ret)
+{
+    if (dsa->params.p == NULL || dsa->params.q == NULL) {
+        ERR_raise(ERR_LIB_DSA, DSA_R_BAD_FFC_PARAMETERS);
+        *ret = FFC_CHECK_INVALID_PQ;
+        return 0;
+    }
+
+    if (BN_num_bits(dsa->params.p) > OPENSSL_DSA_MAX_MODULUS_BITS) {
+        ERR_raise(ERR_LIB_DSA, DSA_R_MODULUS_TOO_LARGE);
+        *ret = FFC_CHECK_INVALID_PQ;
+        return 0;
+    }
+
+    if (BN_num_bits(dsa->params.q) >= BN_num_bits(dsa->params.p)) {
+        ERR_raise(ERR_LIB_DSA, DSA_R_BAD_Q_VALUE);
+        *ret = FFC_CHECK_INVALID_PQ;
+        return 0;
+    }
+
+    return 1;
+}
+
 int ossl_dsa_check_params(const DSA *dsa, int checktype, int *ret)
 {
+    if (!dsa_precheck_params(dsa, ret))
+        return 0;
+
     if (checktype == OSSL_KEYMGMT_VALIDATE_QUICK_CHECK)
         return ossl_ffc_params_simple_validate(dsa->libctx, &dsa->params,
                                                FFC_PARAM_TYPE_DSA, ret);
@@ -39,6 +65,9 @@ int ossl_dsa_check_params(const DSA *dsa, int checktype, int *ret)
  */
 int ossl_dsa_check_pub_key(const DSA *dsa, const BIGNUM *pub_key, int *ret)
 {
+    if (!dsa_precheck_params(dsa, ret))
+        return 0;
+
     return ossl_ffc_validate_public_key(&dsa->params, pub_key, ret)
            && *ret == 0;
 }
@@ -50,6 +79,9 @@ int ossl_dsa_check_pub_key(const DSA *dsa, const BIGNUM *pub_key, int *ret)
  */
 int ossl_dsa_check_pub_key_partial(const DSA *dsa, const BIGNUM *pub_key, int *ret)
 {
+    if (!dsa_precheck_params(dsa, ret))
+        return 0;
+
     return ossl_ffc_validate_public_key_partial(&dsa->params, pub_key, ret)
            && *ret == 0;
 }
@@ -58,8 +90,10 @@ int ossl_dsa_check_priv_key(const DSA *dsa, const BIGNUM *priv_key, int *ret)
 {
     *ret = 0;
 
-    return (dsa->params.q != NULL
-            && ossl_ffc_validate_private_key(dsa->params.q, priv_key, ret));
+    if (!dsa_precheck_params(dsa, ret))
+        return 0;
+
+    return ossl_ffc_validate_private_key(dsa->params.q, priv_key, ret);
 }
 
 /*
@@ -72,8 +106,10 @@ int ossl_dsa_check_pairwise(const DSA *dsa)
     BN_CTX *ctx = NULL;
     BIGNUM *pub_key = NULL;
 
-    if (dsa->params.p == NULL
-        || dsa->params.g == NULL
+    if (!dsa_precheck_params(dsa, &ret))
+        return 0;
+
+    if (dsa->params.g == NULL
         || dsa->priv_key == NULL
         || dsa->pub_key == NULL)
         return 0;

test/recipes/15-test_dsaparam_data/invalid/p10240_q256_too_big.pem

@@ -0,0 +1,57 @@
+-----BEGIN DSA PARAMETERS-----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+-----END DSA PARAMETERS-----