multirom_m86/trampoline_encmnt/encmnt.c

/*
 * This file is part of MultiROM.
 *
 * MultiROM is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * MultiROM is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with MultiROM.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <dirent.h>
#include <errno.h>

#include "../lib/log.h"
#include "../lib/fstab.h"

#include "crypto/lollipop/cryptfs.h"

#define CMD_NONE 0
#define CMD_DECRYPT 1
#define CMD_REMOVE 2
#define CMD_PWTYPE 3

static int get_footer_from_opts(char *output, size_t output_size, const char *opts2)
{
    char *r, *saveptr;
    char *dup = strdup(opts2);
    int res = -1;

    r = strtok_r(dup, ",", &saveptr);
    while(r)
    {
        if(strncmp(r, "encryptable=", sizeof("encryptable=")-1) == 0)
        {
            snprintf(output, output_size, "%s", r + sizeof("encryptable=") - 1);
            res = 0;
            goto exit;
        }

        r = strtok_r(NULL, ",", &saveptr);
    }

exit:
    free(dup);
    return res;
}

static void print_help(char *argv[]) {
    printf("Usage: %s COMMAND ARGUMENTS\n"
        "Available commands:\n"
        "     decrypt PASSWORD - mount encrypted data partition to /realdata using PASSWORD\n"
        "     remove - unmounts encrypted data\n"
        "     pwtype - prints password type as integer\n",
        argv[0]);
}

static int handle_pwtype(int stdout_fd)
{
    if(cryptfs_check_footer() < 0)
    {
        ERROR("cryptfs_check_footer failed!");
        return -1;
    }

    int pwtype = cryptfs_get_password_type();
    if(pwtype < 0)
    {
        ERROR("cryptfs_get_password_type failed!");
        return -1;
    }

    char buff[32];
    snprintf(buff, sizeof(buff), "%d\n", pwtype);
    write(stdout_fd, buff, strlen(buff));
    fsync(stdout_fd);
    return 0;
}

static int handle_decrypt(int stdout_fd, char *password)
{
    DIR *d;
    struct dirent *de;
    char buff[256];
    int res = -1;

    if(cryptfs_check_footer() < 0)
    {
        ERROR("cryptfs_check_footer failed!");
        return -1;
    }

    if(cryptfs_check_passwd(password) < 0)
    {
        ERROR("cryptfs_check_passwd failed!");
        return -1;
    }

    d = opendir("/dev/block/");
    if(!d)
    {
        ERROR("Failed to open /dev/block, wth? %s", strerror(errno));
        return -1;
    }

    // find the block device
    while((de = readdir(d)))
    {
        if(de->d_type == DT_BLK && strncmp(de->d_name, "dm-", 3) == 0)
        {
            snprintf(buff, sizeof(buff), "/dev/block/%s\n", de->d_name);
            write(stdout_fd, buff, strlen(buff));
            fsync(stdout_fd);
            res = 0;
            break;
        }
    }

    closedir(d);
    return res;
}

static int handle_remove(void)
{
    if(delete_crypto_blk_dev("userdata") < 0)
    {
        ERROR("delete_crypto_blk_dev failed!");
        return -1;
    }
    return 0;
}

int main(int argc, char *argv[])
{
    int i;
    int res = 1;
    int cmd = CMD_NONE;
    int stdout_fd;
    char footer_location[256];
    struct fstab *fstab;
    struct fstab_part *p;
    char *argument = NULL;

    for(i = 1; i < argc; ++i)
    {
        if(!strcmp(argv[i], "-h") || !strcmp(argv[i], "--help"))
        {
            print_help(argv);
            return 0;
        }
        else if(cmd == CMD_NONE)
        {
            if(strcmp(argv[i], "decrypt") == 0)
                cmd = CMD_DECRYPT;
            else if(strcmp(argv[i], "remove") == 0)
                cmd = CMD_REMOVE;
            else if(strcmp(argv[i], "pwtype") == 0)
                cmd = CMD_PWTYPE;
        }
        else if(!argument)
        {
            argument = argv[i];
        }
    }

    if(argc == 1 || cmd == CMD_NONE || (cmd == CMD_DECRYPT && !argument))
    {
        print_help(argv);
        return 0;
    }

    fstab = fstab_auto_load();
    if(!fstab)
    {
        ERROR("Failed to load fstab!");
        return 1;
    }

    p = fstab_find_first_by_path(fstab, "/data");
    if(!p)
    {
        ERROR("Failed to find /data partition in fstab\n");
        goto exit;
    }

    if(get_footer_from_opts(footer_location, sizeof(footer_location), p->options2) < 0)
        goto exit;

    INFO("Setting encrypted partition data to %s %s %s\n", p->device, footer_location, p->type);
    set_partition_data(p->device, footer_location, p->type);

    // cryptfs prints informations, we don't want that
    stdout_fd = dup(1);
    freopen("/dev/null", "a", stdout);

    switch(cmd)
    {
        case CMD_PWTYPE:
            if(handle_pwtype(stdout_fd) < 0)
                goto exit;
            break;
        case CMD_DECRYPT:
            if(handle_decrypt(stdout_fd, argument) < 0)
                goto exit;
            break;
        case CMD_REMOVE:
            if(handle_remove() < 0)
                goto exit;
            break;
    }

    res = 0;
exit:
    fstab_destroy(fstab);
    return res;
}