/* Provenance: openssl/openssl rsa_cms_decrypt (vuln).
 * repo: openssl/openssl
 * commit: 6e74b1275cbc1fd1cf7ba32f662602d68501f6ca
 * parent: 6e74b1275cbc1fd1cf7ba32f662602d68501f6ca
 * commit_url: https://github.com/openssl/openssl/commit/af2a5fecd3e71a29e7568f9c1453dec5cebbaff4
 * cve: CVE-2026-28389
 * license: Apache-2.0
 * function: rsa_cms_decrypt
 * relpath: crypto/cms/cms_rsa.c
 */

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;

    pkctx = CMS_RecipientInfo_get0_pkey_ctx(ri);
    if (pkctx == NULL)
        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) {
        ERR_raise(ERR_LIB_CMS, CMS_R_UNSUPPORTED_ENCRYPTION_TYPE);
        return -1;
    }
    /* Decode OAEP parameters */
    oaep = rsa_oaep_decode(cmsalg);

    if (oaep == NULL) {
        ERR_raise(ERR_LIB_CMS, CMS_R_INVALID_OAEP_PARAMETERS);
        goto err;
    }

    mgf1md = ossl_x509_algor_get_md(oaep->maskHash);
    if (mgf1md == NULL)
        goto err;
    md = ossl_x509_algor_get_md(oaep->hashFunc);
    if (md == NULL)
        goto err;

    if (oaep->pSourceFunc != NULL) {
        X509_ALGOR *plab = oaep->pSourceFunc;

        if (OBJ_obj2nid(plab->algorithm) != NID_pSpecified) {
            ERR_raise(ERR_LIB_CMS, CMS_R_UNSUPPORTED_LABEL_SOURCE);
            goto err;
        }
        if (plab->parameter->type != V_ASN1_OCTET_STRING) {
            ERR_raise(ERR_LIB_CMS, CMS_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 (label != NULL
        && EVP_PKEY_CTX_set0_rsa_oaep_label(pkctx, label, labellen) <= 0) {
        OPENSSL_free(label);
        goto err;
    }
    /* Carry on */
    rv = 1;

err:
    RSA_OAEP_PARAMS_free(oaep);
    return rv;
}