/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2023 Beckhoff Automation GmbH & Co. KG
 * Author: Corvin Köhne <corvink@FreeBSD.org>
 */

#include <sys/types.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#ifdef  __FreeBSD__
#include <malloc_np.h>
#else
#include <sys/vmm.h>
#endif
#include <stdlib.h>
#include <unistd.h>

#include "config.h"
#include "tpm_device.h"
#include "tpm_emul.h"

struct tpm_passthru {
        int fd;
};

struct tpm_resp_hdr {
        uint16_t tag;
        uint32_t len;
        uint32_t errcode;
} __packed;

static int
tpm_passthru_init(void **sc, nvlist_t *nvl)
{
#ifndef __FreeBSD__
        /*
         * Until illumos has a TPM 2.0 driver, we can't finish plumbing the TPM
         * pass-through.
         */
        errx(4, "TPM pass-through devices are not yet supported on illumos");
#else
        struct tpm_passthru *tpm;
        const char *path;

        tpm = calloc(1, sizeof(struct tpm_passthru));
        if (tpm == NULL) {
                warnx("%s: failed to allocate tpm passthru", __func__);
                return (ENOMEM);
        }

        path = get_config_value_node(nvl, "path");
        tpm->fd = open(path, O_RDWR);
        if (tpm->fd < 0) {
                warnx("%s: unable to open tpm device \"%s\"", __func__, path);
                return (ENOENT);
        }

        *sc = tpm;
#endif  /* __FreeBSD__ */

        return (0);
}

static int
tpm_passthru_execute_cmd(void *sc, void *cmd, uint32_t cmd_size, void *rsp,
    uint32_t rsp_size)
{
        struct tpm_passthru *tpm;
        ssize_t len;

        if (rsp_size < (ssize_t)sizeof(struct tpm_resp_hdr)) {
                warn("%s: rsp_size of %u is too small", __func__, rsp_size);
                return (EINVAL);
        }

        tpm = sc;

        len = write(tpm->fd, cmd, cmd_size);
        if (len != cmd_size) {
                warn("%s: cmd write failed (bytes written: %zd / %d)", __func__,
                    len, cmd_size);
                return (EFAULT);
        }

        len = read(tpm->fd, rsp, rsp_size);
        if (len < (ssize_t)sizeof(struct tpm_resp_hdr)) {
                warn("%s: rsp read failed (bytes read: %zd / %d)", __func__,
                    len, rsp_size);
                return (EFAULT);
        }

        return (0);
}

static void
tpm_passthru_deinit(void *sc)
{
        struct tpm_passthru *tpm;

        tpm = sc;
        if (tpm == NULL)
                return;

        if (tpm->fd >= 0)
                close(tpm->fd);

        free(tpm);
}

static const struct tpm_emul tpm_emul_passthru = {
        .name = "passthru",
        .init = tpm_passthru_init,
        .deinit = tpm_passthru_deinit,
        .execute_cmd = tpm_passthru_execute_cmd,
};
TPM_EMUL_SET(tpm_emul_passthru);