hwcrypto/keybox/srv.c

/*
 * Copyright (C) 2021 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#define TLOG_TAG "keybox"

#include <assert.h>
#include <inttypes.h>
#include <lk/list.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <uapi/err.h>

#include <interface/keybox/keybox.h>

#include <lib/tipc/tipc.h>
#include <trusty_log.h>

#include "keybox.h"
#include "srv.h"

struct keybox_chan_ctx {
    struct tipc_event_handler evt_handler;
    handle_t chan;
};

static void keybox_port_handler(const uevent_t* ev, void* priv);
static void keybox_chan_handler(const uevent_t* ev, void* priv);

static handle_t keybox_port = INVALID_IPC_HANDLE;

static struct tipc_event_handler keybox_port_evt_handler = {
        .proc = keybox_port_handler,
};

static void keybox_shutdown(struct keybox_chan_ctx* ctx) {
    close(ctx->chan);
    free(ctx);
}

struct full_keybox_unwrap_req {
    struct keybox_unwrap_req unwrap_header;
    uint8_t wrapped_keybox[KEYBOX_MAX_SIZE];
};

struct full_keybox_unwrap_resp {
    struct keybox_resp header;
    struct keybox_unwrap_resp unwrap_header;
};

static int keybox_handle_unwrap(handle_t chan,
                                struct full_keybox_unwrap_req* req,
                                size_t req_size) {
    struct full_keybox_unwrap_resp rsp = {
            .header.cmd = KEYBOX_CMD_UNWRAP | KEYBOX_CMD_RSP_BIT,
    };

    uint8_t output[KEYBOX_MAX_SIZE];
    if (req_size < sizeof(req->unwrap_header)) {
        rsp.header.status = KEYBOX_STATUS_INVALID_REQUEST;
        goto out;
    }

    uint64_t computed_size;
    if (__builtin_add_overflow(req->unwrap_header.wrapped_keybox_len,
                               sizeof(req->unwrap_header), &computed_size)) {
        rsp.header.status = KEYBOX_STATUS_INVALID_REQUEST;
        goto out;
    }
    if (computed_size != req_size) {
        rsp.header.status = KEYBOX_STATUS_INVALID_REQUEST;
        goto out;
    }

    rsp.header.status = keybox_unwrap(
            req->wrapped_keybox, req->unwrap_header.wrapped_keybox_len, output,
            sizeof(output), (size_t*)&rsp.unwrap_header.unwrapped_keybox_len);
    if (rsp.header.status != KEYBOX_STATUS_SUCCESS) {
        goto out;
    }

    return tipc_send2(chan, &rsp, sizeof(rsp), output,
                      rsp.unwrap_header.unwrapped_keybox_len);

out:
    return tipc_send1(chan, &rsp, sizeof(rsp.header));
}

struct full_keybox_req {
    struct keybox_req header;
    union {
        struct full_keybox_unwrap_req unwrap;
    } cmd_header;
};

static int keybox_handle_msg(struct keybox_chan_ctx* ctx) {
    int rc;
    struct full_keybox_req req;
    enum keybox_status status = KEYBOX_STATUS_SUCCESS;
    rc = tipc_recv1(ctx->chan, sizeof(req.header), &req, sizeof(req));
    if (rc < 0) {
        TLOGE("Failed (%d) to receive Keybox message\n", rc);
        return KEYBOX_STATUS_INTERNAL_ERROR;
    }

    size_t cmd_specific_size = (size_t)rc - sizeof(req.header);
    switch (req.header.cmd) {
    case KEYBOX_CMD_UNWRAP:
        rc = keybox_handle_unwrap(ctx->chan, &req.cmd_header.unwrap,
                                  cmd_specific_size);
        break;
    default:
        TLOGE("Invalid Keybox command: %d\n", req.header.cmd);
        struct keybox_resp rsp;
        rsp.cmd = req.header.cmd | KEYBOX_CMD_RSP_BIT;
        rsp.status = KEYBOX_STATUS_INVALID_REQUEST;
        rc = tipc_send1(ctx->chan, &rsp, sizeof(rsp));
    }

    if (rc < 0) {
        status = KEYBOX_STATUS_INTERNAL_ERROR;
    }

    return status;
}

static void keybox_chan_handler(const uevent_t* ev, void* priv) {
    struct keybox_chan_ctx* ctx = (struct keybox_chan_ctx*)priv;
    assert(ctx);
    assert(ev->handle == ctx->chan);

    tipc_handle_chan_errors(ev);
    int rc = 0;
    if (ev->event & IPC_HANDLE_POLL_MSG) {
        rc = keybox_handle_msg(ctx);
    }
    if (ev->event & IPC_HANDLE_POLL_HUP) {
        keybox_shutdown(ctx);
    }
    if (rc) {
        keybox_shutdown(ctx);
    }
}

static void keybox_port_handler(const uevent_t* ev, void* priv) {
    uuid_t peer_uuid;

    tipc_handle_port_errors(ev);

    if (ev->event & IPC_HANDLE_POLL_READY) {
        handle_t chan;

        /* incoming connection: accept it */
        int rc = accept(ev->handle, &peer_uuid);
        if (rc < 0) {
            TLOGE("failed (%d) to accept on port %d\n", rc, ev->handle);
            return;
        }
        chan = (handle_t)rc;

        struct keybox_chan_ctx* ctx = calloc(1, sizeof(struct keybox_chan_ctx));

        if (!ctx) {
            TLOGE("failed to alloc state for chan %d\n", chan);
            close(chan);
            return;
        }

        /* init channel state */
        ctx->evt_handler.priv = ctx;
        ctx->evt_handler.proc = keybox_chan_handler;
        ctx->chan = chan;

        /* attach channel handler */
        rc = set_cookie(chan, &ctx->evt_handler);
        if (rc) {
            TLOGE("failed (%d) to set_cookie on chan %d\n", rc, chan);
            free(ctx);
            close(chan);
            return;
        }
    }
}

/*
 *  Initialize Keybox service
 */
int keybox_start_service(void) {
    int rc;

    TLOGD("Start Keybox service\n");

    /* create Keybox port */
    rc = port_create(KEYBOX_PORT, 1, sizeof(struct full_keybox_req),
                     IPC_PORT_ALLOW_TA_CONNECT);
    if (rc < 0) {
        TLOGE("Failed (%d) to create port '%s'\n", rc, KEYBOX_PORT);
        goto cleanup;
    }

    keybox_port = (handle_t)rc;
    set_cookie(keybox_port, &keybox_port_evt_handler);

    return NO_ERROR;

cleanup:
    close(keybox_port);
    return rc;
}