Commit message: Add PSS parameter check.

Avoid seg fault by checking mgf1 parameter is not NULL. This can be
triggered during certificate verification so could be a DoS attack
against a client or a server enabling client authentication.

Thanks to Loïc Jonas Etienne (Qnective AG) for discovering this bug.

CVE-2015-3194

Reviewed-by: Richard Levitte <levitte@openssl.org>
CVE: CVE-2015-3194
CWE: CWE-476
Vulnerability description: crypto/rsa/rsa_ameth.c in OpenSSL 1.0.1 before 1.0.1q and 1.0.2 before 1.0.2e allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via an RSA PSS ASN.1 signature that lacks a mask generation function parameter.

Project: openssl

static const EVP_MD *rsa_algor_to_md(X509_ALGOR *alg)
{
    const EVP_MD *md;
    if (!alg)
        return EVP_sha1();
    md = EVP_get_digestbyobj(alg->algorithm);
    if (md == NULL)
        RSAerr(RSA_F_RSA_ALGOR_TO_MD, RSA_R_UNKNOWN_DIGEST);
    return md;
}

Project: openssl

static int rsa_cms_decrypt(CMS_RecipientInfo *ri)
{
    EVP_PKEY_CTX *pkctx;
    X509_ALGOR *cmsalg;
    int nid;
    int rv = -1;
    unsigned char *label = NULL;
    int labellen = 0;
    const EVP_MD *mgf1md = NULL, *md = NULL;
    RSA_OAEP_PARAMS *oaep;
    X509_ALGOR *maskHash;
    pkctx = CMS_RecipientInfo_get0_pkey_ctx(ri);
    if (!pkctx)
        return 0;
    if (!CMS_RecipientInfo_ktri_get0_algs(ri, NULL, NULL, &cmsalg))
        return -1;
    nid = OBJ_obj2nid(cmsalg->algorithm);
    if (nid == NID_rsaEncryption)
        return 1;
    if (nid != NID_rsaesOaep) {
        RSAerr(RSA_F_RSA_CMS_DECRYPT, RSA_R_UNSUPPORTED_ENCRYPTION_TYPE);
        return -1;
    }
    /* Decode OAEP parameters */
    oaep = rsa_oaep_decode(cmsalg, &maskHash);

    if (oaep == NULL) {
        RSAerr(RSA_F_RSA_CMS_DECRYPT, RSA_R_INVALID_OAEP_PARAMETERS);
        goto err;
    }

    mgf1md = rsa_mgf1_to_md(oaep->maskGenFunc, maskHash);
    if (!mgf1md)
        goto err;
    md = rsa_algor_to_md(oaep->hashFunc);
    if (!md)
        goto err;

    if (oaep->pSourceFunc) {
        X509_ALGOR *plab = oaep->pSourceFunc;
        if (OBJ_obj2nid(plab->algorithm) != NID_pSpecified) {
            RSAerr(RSA_F_RSA_CMS_DECRYPT, RSA_R_UNSUPPORTED_LABEL_SOURCE);
            goto err;
        }
        if (plab->parameter->type != V_ASN1_OCTET_STRING) {
            RSAerr(RSA_F_RSA_CMS_DECRYPT, RSA_R_INVALID_LABEL);
            goto err;
        }

        label = plab->parameter->value.octet_string->data;
        /* Stop label being freed when OAEP parameters are freed */
        plab->parameter->value.octet_string->data = NULL;
        labellen = plab->parameter->value.octet_string->length;
    }

    if (EVP_PKEY_CTX_set_rsa_padding(pkctx, RSA_PKCS1_OAEP_PADDING) <= 0)
        goto err;
    if (EVP_PKEY_CTX_set_rsa_oaep_md(pkctx, md) <= 0)
        goto err;
    if (EVP_PKEY_CTX_set_rsa_mgf1_md(pkctx, mgf1md) <= 0)
        goto err;
    if (EVP_PKEY_CTX_set0_rsa_oaep_label(pkctx, label, labellen) <= 0)
        goto err;
    /* Carry on */
    rv = 1;

 err:
    RSA_OAEP_PARAMS_free(oaep);
    if (maskHash)
        X509_ALGOR_free(maskHash);
    return rv;
}

Project: openssl

static int rsa_cms_encrypt(CMS_RecipientInfo *ri)
{
    const EVP_MD *md, *mgf1md;
    RSA_OAEP_PARAMS *oaep = NULL;
    ASN1_STRING *os = NULL;
    X509_ALGOR *alg;
    EVP_PKEY_CTX *pkctx = CMS_RecipientInfo_get0_pkey_ctx(ri);
    int pad_mode = RSA_PKCS1_PADDING, rv = 0, labellen;
    unsigned char *label;
    CMS_RecipientInfo_ktri_get0_algs(ri, NULL, NULL, &alg);
    if (pkctx) {
        if (EVP_PKEY_CTX_get_rsa_padding(pkctx, &pad_mode) <= 0)
            return 0;
    }
    if (pad_mode == RSA_PKCS1_PADDING) {
        X509_ALGOR_set0(alg, OBJ_nid2obj(NID_rsaEncryption), V_ASN1_NULL, 0);
        return 1;
    }
    /* Not supported */
    if (pad_mode != RSA_PKCS1_OAEP_PADDING)
        return 0;
    if (EVP_PKEY_CTX_get_rsa_oaep_md(pkctx, &md) <= 0)
        goto err;
    if (EVP_PKEY_CTX_get_rsa_mgf1_md(pkctx, &mgf1md) <= 0)
        goto err;
    labellen = EVP_PKEY_CTX_get0_rsa_oaep_label(pkctx, &label);
    if (labellen < 0)
        goto err;
    oaep = RSA_OAEP_PARAMS_new();
    if (!oaep)
        goto err;
    if (!rsa_md_to_algor(&oaep->hashFunc, md))
        goto err;
    if (!rsa_md_to_mgf1(&oaep->maskGenFunc, mgf1md))
        goto err;
    if (labellen > 0) {
        ASN1_OCTET_STRING *los = ASN1_OCTET_STRING_new();
        oaep->pSourceFunc = X509_ALGOR_new();
        if (!oaep->pSourceFunc)
            goto err;
        if (!los)
            goto err;
        if (!ASN1_OCTET_STRING_set(los, label, labellen)) {
            ASN1_OCTET_STRING_free(los);
            goto err;
        }
        X509_ALGOR_set0(oaep->pSourceFunc, OBJ_nid2obj(NID_pSpecified),
                        V_ASN1_OCTET_STRING, los);
    }
    /* create string with pss parameter encoding. */
    if (!ASN1_item_pack(oaep, ASN1_ITEM_rptr(RSA_OAEP_PARAMS), &os))
         goto err;
    X509_ALGOR_set0(alg, OBJ_nid2obj(NID_rsaesOaep), V_ASN1_SEQUENCE, os);
    os = NULL;
    rv = 1;
 err:
    if (oaep)
        RSA_OAEP_PARAMS_free(oaep);
    if (os)
        ASN1_STRING_free(os);
    return rv;
}

Project: openssl

static int rsa_cms_sign(CMS_SignerInfo *si)
{
    int pad_mode = RSA_PKCS1_PADDING;
    X509_ALGOR *alg;
    EVP_PKEY_CTX *pkctx = CMS_SignerInfo_get0_pkey_ctx(si);
    ASN1_STRING *os = NULL;
    CMS_SignerInfo_get0_algs(si, NULL, NULL, NULL, &alg);
    if (pkctx) {
        if (EVP_PKEY_CTX_get_rsa_padding(pkctx, &pad_mode) <= 0)
            return 0;
    }
    if (pad_mode == RSA_PKCS1_PADDING) {
        X509_ALGOR_set0(alg, OBJ_nid2obj(NID_rsaEncryption), V_ASN1_NULL, 0);
        return 1;
    }
    /* We don't support it */
    if (pad_mode != RSA_PKCS1_PSS_PADDING)
        return 0;
    os = rsa_ctx_to_pss(pkctx);
    if (!os)
        return 0;
    X509_ALGOR_set0(alg, OBJ_nid2obj(NID_rsassaPss), V_ASN1_SEQUENCE, os);
    return 1;
}

Project: openssl

static int rsa_cms_verify(CMS_SignerInfo *si)
{
    int nid, nid2;
    X509_ALGOR *alg;
    EVP_PKEY_CTX *pkctx = CMS_SignerInfo_get0_pkey_ctx(si);
    CMS_SignerInfo_get0_algs(si, NULL, NULL, NULL, &alg);
    nid = OBJ_obj2nid(alg->algorithm);
    if (nid == NID_rsaEncryption)
        return 1;
    if (nid == NID_rsassaPss)
        return rsa_pss_to_ctx(NULL, pkctx, alg, NULL);
    /* Workaround for some implementation that use a signature OID */
    if (OBJ_find_sigid_algs(nid, NULL, &nid2)) {
        if (nid2 == NID_rsaEncryption)
            return 1;
    }
    return 0;
}

Project: openssl

static ASN1_STRING *rsa_ctx_to_pss(EVP_PKEY_CTX *pkctx)
{
    const EVP_MD *sigmd, *mgf1md;
    RSA_PSS_PARAMS *pss = NULL;
    ASN1_STRING *os = NULL;
    EVP_PKEY *pk = EVP_PKEY_CTX_get0_pkey(pkctx);
    int saltlen, rv = 0;
    if (EVP_PKEY_CTX_get_signature_md(pkctx, &sigmd) <= 0)
        goto err;
    if (EVP_PKEY_CTX_get_rsa_mgf1_md(pkctx, &mgf1md) <= 0)
        goto err;
    if (!EVP_PKEY_CTX_get_rsa_pss_saltlen(pkctx, &saltlen))
        goto err;
    if (saltlen == -1)
        saltlen = EVP_MD_size(sigmd);
    else if (saltlen == -2) {
        saltlen = EVP_PKEY_size(pk) - EVP_MD_size(sigmd) - 2;
        if (((EVP_PKEY_bits(pk) - 1) & 0x7) == 0)
            saltlen--;
    }
    pss = RSA_PSS_PARAMS_new();
    if (!pss)
        goto err;
    if (saltlen != 20) {
        pss->saltLength = ASN1_INTEGER_new();
        if (!pss->saltLength)
            goto err;
        if (!ASN1_INTEGER_set(pss->saltLength, saltlen))
            goto err;
    }
    if (!rsa_md_to_algor(&pss->hashAlgorithm, sigmd))
        goto err;
    if (!rsa_md_to_mgf1(&pss->maskGenAlgorithm, mgf1md))
        goto err;
    /* Finally create string with pss parameter encoding. */
    if (!ASN1_item_pack(pss, ASN1_ITEM_rptr(RSA_PSS_PARAMS), &os))
         goto err;
    rv = 1;
 err:
    if (pss)
        RSA_PSS_PARAMS_free(pss);
    if (rv)
        return os;
    if (os)
        ASN1_STRING_free(os);
    return NULL;
}

Project: openssl

static int rsa_item_verify(EVP_MD_CTX *ctx, const ASN1_ITEM *it, void *asn,
                           X509_ALGOR *sigalg, ASN1_BIT_STRING *sig,
                           EVP_PKEY *pkey)
{
    /* Sanity check: make sure it is PSS */
    if (OBJ_obj2nid(sigalg->algorithm) != NID_rsassaPss) {
        RSAerr(RSA_F_RSA_ITEM_VERIFY, RSA_R_UNSUPPORTED_SIGNATURE_TYPE);
        return -1;
    }
    if (rsa_pss_to_ctx(ctx, NULL, sigalg, pkey) > 0) {
        /* Carry on */
        return 2;
    }
    return -1;
}

Project: openssl

static int rsa_md_to_mgf1(X509_ALGOR **palg, const EVP_MD *mgf1md)
{
    X509_ALGOR *algtmp = NULL;
    ASN1_STRING *stmp = NULL;
    *palg = NULL;
    if (EVP_MD_type(mgf1md) == NID_sha1)
        return 1;
    /* need to embed algorithm ID inside another */
    if (!rsa_md_to_algor(&algtmp, mgf1md))
        goto err;
    if (!ASN1_item_pack(algtmp, ASN1_ITEM_rptr(X509_ALGOR), &stmp))
         goto err;
    *palg = X509_ALGOR_new();
    if (!*palg)
        goto err;
    X509_ALGOR_set0(*palg, OBJ_nid2obj(NID_mgf1), V_ASN1_SEQUENCE, stmp);
    stmp = NULL;
 err:
    if (stmp)
        ASN1_STRING_free(stmp);
    if (algtmp)
        X509_ALGOR_free(algtmp);
    if (*palg)
        return 1;
    return 0;
}

Project: openssl

static const EVP_MD *rsa_mgf1_to_md(X509_ALGOR *alg, X509_ALGOR *maskHash)
{
    const EVP_MD *md;
    if (!alg)
        return EVP_sha1();
    /* Check mask and lookup mask hash algorithm */
    if (OBJ_obj2nid(alg->algorithm) != NID_mgf1) {
        RSAerr(RSA_F_RSA_MGF1_TO_MD, RSA_R_UNSUPPORTED_MASK_ALGORITHM);
        return NULL;
    }
    if (!maskHash) {
        RSAerr(RSA_F_RSA_MGF1_TO_MD, RSA_R_UNSUPPORTED_MASK_PARAMETER);
        return NULL;
    }
    md = EVP_get_digestbyobj(maskHash->algorithm);
    if (md == NULL) {
        RSAerr(RSA_F_RSA_MGF1_TO_MD, RSA_R_UNKNOWN_MASK_DIGEST);
        return NULL;
    }
    return md;
}

Project: openssl

static int rsa_pkey_ctrl(EVP_PKEY *pkey, int op, long arg1, void *arg2)
{
    X509_ALGOR *alg = NULL;
    switch (op) {

    case ASN1_PKEY_CTRL_PKCS7_SIGN:
        if (arg1 == 0)
            PKCS7_SIGNER_INFO_get0_algs(arg2, NULL, NULL, &alg);
        break;

    case ASN1_PKEY_CTRL_PKCS7_ENCRYPT:
        if (arg1 == 0)
            PKCS7_RECIP_INFO_get0_alg(arg2, &alg);
        break;
#ifndef OPENSSL_NO_CMS
    case ASN1_PKEY_CTRL_CMS_SIGN:
        if (arg1 == 0)
            return rsa_cms_sign(arg2);
        else if (arg1 == 1)
            return rsa_cms_verify(arg2);
        break;

    case ASN1_PKEY_CTRL_CMS_ENVELOPE:
        if (arg1 == 0)
            return rsa_cms_encrypt(arg2);
        else if (arg1 == 1)
            return rsa_cms_decrypt(arg2);
        break;

    case ASN1_PKEY_CTRL_CMS_RI_TYPE:
        *(int *)arg2 = CMS_RECIPINFO_TRANS;
        return 1;
#endif

    case ASN1_PKEY_CTRL_DEFAULT_MD_NID:
        *(int *)arg2 = NID_sha256;
        return 1;

    default:
        return -2;

    }

    if (alg)
        X509_ALGOR_set0(alg, OBJ_nid2obj(NID_rsaEncryption), V_ASN1_NULL, 0);

    return 1;

}

Project: openssl

static int rsa_pss_to_ctx(EVP_MD_CTX *ctx, EVP_PKEY_CTX *pkctx,
                          X509_ALGOR *sigalg, EVP_PKEY *pkey)
{
    int rv = -1;
    int saltlen;
    const EVP_MD *mgf1md = NULL, *md = NULL;
    RSA_PSS_PARAMS *pss;
    X509_ALGOR *maskHash;
    /* Sanity check: make sure it is PSS */
    if (OBJ_obj2nid(sigalg->algorithm) != NID_rsassaPss) {
        RSAerr(RSA_F_RSA_PSS_TO_CTX, RSA_R_UNSUPPORTED_SIGNATURE_TYPE);
        return -1;
    }
    /* Decode PSS parameters */
    pss = rsa_pss_decode(sigalg, &maskHash);

    if (pss == NULL) {
        RSAerr(RSA_F_RSA_PSS_TO_CTX, RSA_R_INVALID_PSS_PARAMETERS);
        goto err;
    }
    mgf1md = rsa_mgf1_to_md(pss->maskGenAlgorithm, maskHash);
    if (!mgf1md)
        goto err;
    md = rsa_algor_to_md(pss->hashAlgorithm);
    if (!md)
        goto err;

    if (pss->saltLength) {
        saltlen = ASN1_INTEGER_get(pss->saltLength);

        /*
         * Could perform more salt length sanity checks but the main RSA
         * routines will trap other invalid values anyway.
         */
        if (saltlen < 0) {
            RSAerr(RSA_F_RSA_PSS_TO_CTX, RSA_R_INVALID_SALT_LENGTH);
            goto err;
        }
    } else
        saltlen = 20;

    /*
     * low-level routines support only trailer field 0xbc (value 1) and
     * PKCS#1 says we should reject any other value anyway.
     */
    if (pss->trailerField && ASN1_INTEGER_get(pss->trailerField) != 1) {
        RSAerr(RSA_F_RSA_PSS_TO_CTX, RSA_R_INVALID_TRAILER);
        goto err;
    }

    /* We have all parameters now set up context */

    if (pkey) {
        if (!EVP_DigestVerifyInit(ctx, &pkctx, md, NULL, pkey))
            goto err;
    } else {
        const EVP_MD *checkmd;
        if (EVP_PKEY_CTX_get_signature_md(pkctx, &checkmd) <= 0)
            goto err;
        if (EVP_MD_type(md) != EVP_MD_type(checkmd)) {
            RSAerr(RSA_F_RSA_PSS_TO_CTX, RSA_R_DIGEST_DOES_NOT_MATCH);
            goto err;
        }
    }

    if (EVP_PKEY_CTX_set_rsa_padding(pkctx, RSA_PKCS1_PSS_PADDING) <= 0)
        goto err;

    if (EVP_PKEY_CTX_set_rsa_pss_saltlen(pkctx, saltlen) <= 0)
        goto err;

    if (EVP_PKEY_CTX_set_rsa_mgf1_md(pkctx, mgf1md) <= 0)
        goto err;
    /* Carry on */
    rv = 1;

 err:
    RSA_PSS_PARAMS_free(pss);
    if (maskHash)
        X509_ALGOR_free(maskHash);
    return rv;
}