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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)
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CHANGES.md

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

crypto/dsa/dsa_check.c

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@@ -19,8 +19,34 @@
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#include "dsa_local.h"
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#include "crypto/dsa.h"
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static int dsa_precheck_params(const DSA *dsa, int *ret)
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{
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if (dsa->params.p == NULL || dsa->params.q == NULL) {
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ERR_raise(ERR_LIB_DSA, DSA_R_BAD_FFC_PARAMETERS);
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*ret = FFC_CHECK_INVALID_PQ;
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return 0;
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}
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if (BN_num_bits(dsa->params.p) > OPENSSL_DSA_MAX_MODULUS_BITS) {
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ERR_raise(ERR_LIB_DSA, DSA_R_MODULUS_TOO_LARGE);
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*ret = FFC_CHECK_INVALID_PQ;
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return 0;
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}
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if (BN_num_bits(dsa->params.q) >= BN_num_bits(dsa->params.p)) {
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ERR_raise(ERR_LIB_DSA, DSA_R_BAD_Q_VALUE);
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*ret = FFC_CHECK_INVALID_PQ;
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return 0;
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}
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return 1;
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}
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int ossl_dsa_check_params(const DSA *dsa, int checktype, int *ret)
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{
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if (!dsa_precheck_params(dsa, ret))
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return 0;
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if (checktype == OSSL_KEYMGMT_VALIDATE_QUICK_CHECK)
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return ossl_ffc_params_simple_validate(dsa->libctx, &dsa->params,
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FFC_PARAM_TYPE_DSA, ret);
@@ -39,6 +65,9 @@ int ossl_dsa_check_params(const DSA *dsa, int checktype, int *ret)
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*/
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int ossl_dsa_check_pub_key(const DSA *dsa, const BIGNUM *pub_key, int *ret)
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{
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if (!dsa_precheck_params(dsa, ret))
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return 0;
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return ossl_ffc_validate_public_key(&dsa->params, pub_key, ret)
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&& *ret == 0;
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}
@@ -50,6 +79,9 @@ int ossl_dsa_check_pub_key(const DSA *dsa, const BIGNUM *pub_key, int *ret)
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*/
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int ossl_dsa_check_pub_key_partial(const DSA *dsa, const BIGNUM *pub_key, int *ret)
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{
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if (!dsa_precheck_params(dsa, ret))
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return 0;
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return ossl_ffc_validate_public_key_partial(&dsa->params, pub_key, ret)
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&& *ret == 0;
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}
@@ -58,8 +90,10 @@ int ossl_dsa_check_priv_key(const DSA *dsa, const BIGNUM *priv_key, int *ret)
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{
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*ret = 0;
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return (dsa->params.q != NULL
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&& ossl_ffc_validate_private_key(dsa->params.q, priv_key, ret));
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if (!dsa_precheck_params(dsa, ret))
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return 0;
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return ossl_ffc_validate_private_key(dsa->params.q, priv_key, ret);
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}
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/*
@@ -72,8 +106,10 @@ int ossl_dsa_check_pairwise(const DSA *dsa)
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BN_CTX *ctx = NULL;
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BIGNUM *pub_key = NULL;
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if (dsa->params.p == NULL
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|| dsa->params.g == NULL
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if (!dsa_precheck_params(dsa, &ret))
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return 0;
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if (dsa->params.g == NULL
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|| dsa->priv_key == NULL
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|| dsa->pub_key == NULL)
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return 0;
Lines changed: 57 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,57 @@
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-----BEGIN DSA PARAMETERS-----
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3+
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5+
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6+
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7+
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8+
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9+
pR71bRZrEEegDj0LH2HCgI5W6H3blOS9A0kUTddCoQXr2lsVdiPtRbPKH1gcd9FQ
10+
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11+
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12+
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13+
koyEmMSp53lldCzp158PrIanqSp2rksMR8SmmCL3FwfAp2OjqFMEglG9DT8x0WaN
14+
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15+
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16+
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18+
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19+
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20+
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21+
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22+
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24+
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35+
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48+
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49+
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50+
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51+
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52+
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53+
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56+
vKuje86bePD6kD/LH3wmkA==
57+
-----END DSA PARAMETERS-----

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