254 lines
8.2 KiB
C
254 lines
8.2 KiB
C
/***
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This file is part of systemd.
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Copyright 2016 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <stdbool.h>
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#include <stdlib.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include "alloc-util.h"
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#include "fd-util.h"
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#include "fileio.h"
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#include "fstab-util.h"
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#include "hexdecoct.h"
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#include "id128-util.h"
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#include "mkdir.h"
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#include "parse-util.h"
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#include "proc-cmdline.h"
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#include "string-util.h"
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#include "unit-name.h"
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static char *arg_dest = NULL;
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static bool arg_enabled = true;
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static char *arg_root_hash = NULL;
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static char *arg_data_what = NULL;
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static char *arg_hash_what = NULL;
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static int create_device(void) {
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_cleanup_free_ char *u = NULL, *v = NULL, *d = NULL, *e = NULL;
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_cleanup_fclose_ FILE *f = NULL;
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const char *p, *to;
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int r;
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/* If all three pieces of information are missing, then verity is turned off */
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if (!arg_root_hash && !arg_data_what && !arg_hash_what)
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return 0;
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/* if one of them is missing however, the data is simply incomplete and this is an error */
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if (!arg_root_hash)
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log_error("Verity information incomplete, root hash unspecified.");
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if (!arg_data_what)
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log_error("Verity information incomplete, root data device unspecified.");
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if (!arg_hash_what)
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log_error("Verity information incomplete, root hash device unspecified.");
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if (!arg_root_hash || !arg_data_what || !arg_hash_what)
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return -EINVAL;
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log_debug("Using root verity data device %s,\n"
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" hash device %s,\n"
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" and root hash %s.", arg_data_what, arg_hash_what, arg_root_hash);
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p = strjoina(arg_dest, "/systemd-veritysetup@root.service");
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u = fstab_node_to_udev_node(arg_data_what);
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if (!u)
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return log_oom();
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v = fstab_node_to_udev_node(arg_hash_what);
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if (!v)
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return log_oom();
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r = unit_name_from_path(u, ".device", &d);
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if (r < 0)
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return log_error_errno(r, "Failed to to generate unit name: %m");
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r = unit_name_from_path(v, ".device", &e);
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if (r < 0)
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return log_error_errno(r, "Failed to to generate unit name: %m");
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f = fopen(p, "wxe");
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if (!f)
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return log_error_errno(errno, "Failed to create unit file %s: %m", p);
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fprintf(f,
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"# Automatically generated by systemd-veritysetup-generator\n\n"
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"[Unit]\n"
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"Description=Integrity Protection Setup for %%I\n"
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"Documentation=man:systemd-veritysetup-generator(8) man:systemd-veritysetup@.service(8)\n"
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"SourcePath=/proc/cmdline\n"
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"DefaultDependencies=no\n"
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"Conflicts=umount.target\n"
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"BindsTo=%s %s\n"
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"IgnoreOnIsolate=true\n"
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"After=cryptsetup-pre.target %s %s\n"
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"Before=cryptsetup.target umount.target\n"
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"\n[Service]\n"
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"Type=oneshot\n"
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"RemainAfterExit=yes\n"
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"ExecStart=" ROOTLIBEXECDIR "/systemd-veritysetup attach root '%s' '%s' '%s'\n"
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"ExecStop=" ROOTLIBEXECDIR "/systemd-veritysetup detach root\n",
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d, e,
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d, e,
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u, v, arg_root_hash);
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r = fflush_and_check(f);
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if (r < 0)
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return log_error_errno(r, "Failed to write file %s: %m", p);
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to = strjoina(arg_dest, "/cryptsetup.target.requires/systemd-veritysetup@root.service");
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(void) mkdir_parents(to, 0755);
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if (symlink("../systemd-veritysetup@root.service", to) < 0)
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return log_error_errno(errno, "Failed to create symlink %s: %m", to);
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return 0;
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}
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static int parse_proc_cmdline_item(const char *key, const char *value, void *data) {
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int r;
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if (streq(key, "systemd.verity")) {
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r = value ? parse_boolean(value) : 1;
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if (r < 0)
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log_warning("Failed to parse verity= kernel command line switch %s. Ignoring.", value);
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else
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arg_enabled = r;
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} else if (streq(key, "roothash")) {
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if (proc_cmdline_value_missing(key, value))
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return 0;
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r = free_and_strdup(&arg_root_hash, value);
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if (r < 0)
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return log_oom();
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} else if (streq(key, "systemd.verity_root_data")) {
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if (proc_cmdline_value_missing(key, value))
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return 0;
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r = free_and_strdup(&arg_data_what, value);
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if (r < 0)
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return log_oom();
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} else if (streq(key, "systemd.verity_root_hash")) {
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if (proc_cmdline_value_missing(key, value))
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return 0;
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r = free_and_strdup(&arg_hash_what, value);
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if (r < 0)
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return log_oom();
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}
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return 0;
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}
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static int determine_devices(void) {
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_cleanup_free_ void *m = NULL;
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sd_id128_t root_uuid, verity_uuid;
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char ids[37];
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size_t l;
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int r;
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/* Try to automatically derive the root data and hash device paths from the root hash */
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if (!arg_root_hash)
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return 0;
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if (arg_data_what && arg_hash_what)
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return 0;
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r = unhexmem(arg_root_hash, strlen(arg_root_hash), &m, &l);
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if (r < 0)
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return log_error_errno(r, "Failed to parse root hash: %s", arg_root_hash);
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if (l < sizeof(sd_id128_t)) {
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log_debug("Root hash is shorter than 128 bits (32 characters), ignoring for discovering verity partition.");
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return 0;
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}
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if (!arg_data_what) {
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memcpy(&root_uuid, m, sizeof(root_uuid));
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arg_data_what = strjoin("/dev/disk/by-partuuid/", id128_to_uuid_string(root_uuid, ids));
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if (!arg_data_what)
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return log_oom();
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}
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if (!arg_hash_what) {
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memcpy(&verity_uuid, (uint8_t*) m + l - sizeof(verity_uuid), sizeof(verity_uuid));
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arg_hash_what = strjoin("/dev/disk/by-partuuid/", id128_to_uuid_string(verity_uuid, ids));
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if (!arg_hash_what)
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return log_oom();
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}
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return 1;
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}
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int main(int argc, char *argv[]) {
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int r;
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if (argc > 1 && argc != 4) {
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log_error("This program takes three or no arguments.");
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return EXIT_FAILURE;
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}
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if (argc > 1)
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arg_dest = argv[1];
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log_set_target(LOG_TARGET_SAFE);
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log_parse_environment();
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log_open();
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umask(0022);
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r = proc_cmdline_parse(parse_proc_cmdline_item, NULL, PROC_CMDLINE_STRIP_RD_PREFIX);
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if (r < 0) {
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log_warning_errno(r, "Failed to parse kernel command line: %m");
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goto finish;
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}
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/* For now we only support the root device on verity. Later on we might want to add support for /etc/veritytab
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* or similar to define additional mappings */
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if (!arg_enabled) {
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r = 0;
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goto finish;
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}
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r = determine_devices();
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if (r < 0)
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goto finish;
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r = create_device();
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if (r < 0)
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goto finish;
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r = 0;
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finish:
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free(arg_root_hash);
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free(arg_data_what);
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free(arg_hash_what);
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return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
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}
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