/***
This file is part of systemd.
Copyright 2016 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <stdbool.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <unistd.h>
#include "alloc-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "fstab-util.h"
#include "hexdecoct.h"
#include "id128-util.h"
#include "mkdir.h"
#include "parse-util.h"
#include "proc-cmdline.h"
#include "string-util.h"
#include "unit-name.h"
static char *arg_dest = NULL;
static bool arg_enabled = true;
static char *arg_root_hash = NULL;
static char *arg_data_what = NULL;
static char *arg_hash_what = NULL;
static int create_device(void) {
_cleanup_free_ char *u = NULL, *v = NULL, *d = NULL, *e = NULL;
_cleanup_fclose_ FILE *f = NULL;
const char *p, *to;
int r;
/* If all three pieces of information are missing, then verity is turned off */
if (!arg_root_hash && !arg_data_what && !arg_hash_what)
return 0;
/* if one of them is missing however, the data is simply incomplete and this is an error */
if (!arg_root_hash)
log_error("Verity information incomplete, root hash unspecified.");
if (!arg_data_what)
log_error("Verity information incomplete, root data device unspecified.");
if (!arg_hash_what)
log_error("Verity information incomplete, root hash device unspecified.");
if (!arg_root_hash || !arg_data_what || !arg_hash_what)
return -EINVAL;
log_debug("Using root verity data device %s,\n"
" hash device %s,\n"
" and root hash %s.", arg_data_what, arg_hash_what, arg_root_hash);
p = strjoina(arg_dest, "/systemd-veritysetup@root.service");
u = fstab_node_to_udev_node(arg_data_what);
if (!u)
return log_oom();
v = fstab_node_to_udev_node(arg_hash_what);
if (!v)
return log_oom();
r = unit_name_from_path(u, ".device", &d);
if (r < 0)
return log_error_errno(r, "Failed to to generate unit name: %m");
r = unit_name_from_path(v, ".device", &e);
if (r < 0)
return log_error_errno(r, "Failed to to generate unit name: %m");
f = fopen(p, "wxe");
if (!f)
return log_error_errno(errno, "Failed to create unit file %s: %m", p);
fprintf(f,
"# Automatically generated by systemd-veritysetup-generator\n\n"
"[Unit]\n"
"Description=Integrity Protection Setup for %%I\n"
"Documentation=man:systemd-veritysetup-generator(8) man:systemd-veritysetup@.service(8)\n"
"SourcePath=/proc/cmdline\n"
"DefaultDependencies=no\n"
"Conflicts=umount.target\n"
"BindsTo=%s %s\n"
"IgnoreOnIsolate=true\n"
"After=cryptsetup-pre.target %s %s\n"
"Before=cryptsetup.target umount.target\n"
"\n[Service]\n"
"Type=oneshot\n"
"RemainAfterExit=yes\n"
"ExecStart=" ROOTLIBEXECDIR "/systemd-veritysetup attach root '%s' '%s' '%s'\n"
"ExecStop=" ROOTLIBEXECDIR "/systemd-veritysetup detach root\n",
d, e,
d, e,
u, v, arg_root_hash);
r = fflush_and_check(f);
if (r < 0)
return log_error_errno(r, "Failed to write file %s: %m", p);
to = strjoina(arg_dest, "/cryptsetup.target.requires/systemd-veritysetup@root.service");
(void) mkdir_parents(to, 0755);
if (symlink("../systemd-veritysetup@root.service", to) < 0)
return log_error_errno(errno, "Failed to create symlink %s: %m", to);
return 0;
}
static int parse_proc_cmdline_item(const char *key, const char *value, void *data) {
int r;
if (streq(key, "systemd.verity")) {
r = value ? parse_boolean(value) : 1;
if (r < 0)
log_warning("Failed to parse verity= kernel command line switch %s. Ignoring.", value);
else
arg_enabled = r;
} else if (streq(key, "roothash")) {
if (proc_cmdline_value_missing(key, value))
return 0;
r = free_and_strdup(&arg_root_hash, value);
if (r < 0)
return log_oom();
} else if (streq(key, "systemd.verity_root_data")) {
if (proc_cmdline_value_missing(key, value))
return 0;
r = free_and_strdup(&arg_data_what, value);
if (r < 0)
return log_oom();
} else if (streq(key, "systemd.verity_root_hash")) {
if (proc_cmdline_value_missing(key, value))
return 0;
r = free_and_strdup(&arg_hash_what, value);
if (r < 0)
return log_oom();
}
return 0;
}
static int determine_devices(void) {
_cleanup_free_ void *m = NULL;
sd_id128_t root_uuid, verity_uuid;
char ids[37];
size_t l;
int r;
/* Try to automatically derive the root data and hash device paths from the root hash */
if (!arg_root_hash)
return 0;
if (arg_data_what && arg_hash_what)
return 0;
r = unhexmem(arg_root_hash, strlen(arg_root_hash), &m, &l);
if (r < 0)
return log_error_errno(r, "Failed to parse root hash: %s", arg_root_hash);
if (l < sizeof(sd_id128_t)) {
log_debug("Root hash is shorter than 128 bits (32 characters), ignoring for discovering verity partition.");
return 0;
}
if (!arg_data_what) {
memcpy(&root_uuid, m, sizeof(root_uuid));
arg_data_what = strjoin("/dev/disk/by-partuuid/", id128_to_uuid_string(root_uuid, ids));
if (!arg_data_what)
return log_oom();
}
if (!arg_hash_what) {
memcpy(&verity_uuid, (uint8_t*) m + l - sizeof(verity_uuid), sizeof(verity_uuid));
arg_hash_what = strjoin("/dev/disk/by-partuuid/", id128_to_uuid_string(verity_uuid, ids));
if (!arg_hash_what)
return log_oom();
}
return 1;
}
int main(int argc, char *argv[]) {
int r;
if (argc > 1 && argc != 4) {
log_error("This program takes three or no arguments.");
return EXIT_FAILURE;
}
if (argc > 1)
arg_dest = argv[1];
log_set_target(LOG_TARGET_SAFE);
log_parse_environment();
log_open();
umask(0022);
r = proc_cmdline_parse(parse_proc_cmdline_item, NULL, PROC_CMDLINE_STRIP_RD_PREFIX);
if (r < 0) {
log_warning_errno(r, "Failed to parse kernel command line: %m");
goto finish;
}
/* For now we only support the root device on verity. Later on we might want to add support for /etc/veritytab
* or similar to define additional mappings */
if (!arg_enabled) {
r = 0;
goto finish;
}
r = determine_devices();
if (r < 0)
goto finish;
r = create_device();
if (r < 0)
goto finish;
r = 0;
finish:
free(arg_root_hash);
free(arg_data_what);
free(arg_hash_what);
return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
}