path: root/src/cryptsetup/cryptsetup-generator.c

/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/

/***
  This file is part of systemd.

  Copyright 2010 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 <string.h>
#include <errno.h>
#include <unistd.h>

#include "log.h"
#include "util.h"
#include "unit-name.h"
#include "mkdir.h"
#include "strv.h"
#include "fileio.h"
#include "path-util.h"
#include "dropin.h"
#include "generator.h"

static const char *arg_dest = "/tmp";
static bool arg_enabled = true;
static bool arg_read_crypttab = true;
static char **arg_disks = NULL;
static char **arg_options = NULL;
static char *arg_keyfile = NULL;

static bool has_option(const char *haystack, const char *needle) {
        const char *f = haystack;
        size_t l;

        assert(needle);

        if (!haystack)
                return false;

        l = strlen(needle);

        while ((f = strstr(f, needle))) {

                if (f > haystack && f[-1] != ',') {
                        f++;
                        continue;
                }

                if (f[l] != 0 && f[l] != ',') {
                        f++;
                        continue;
                }

                return true;
        }

        return false;
}

static int create_disk(
                const char *name,
                const char *device,
                const char *password,
                const char *options) {

        _cleanup_free_ char *p = NULL, *n = NULL, *d = NULL, *u = NULL, *to = NULL, *e = NULL,
                *filtered = NULL;
        _cleanup_fclose_ FILE *f = NULL;
        bool noauto, nofail, tmp, swap;
        char *from;
        int r;

        assert(name);
        assert(device);

        noauto = has_option(options, "noauto");
        nofail = has_option(options, "nofail");
        tmp = has_option(options, "tmp");
        swap = has_option(options, "swap");

        if (tmp && swap) {
                log_error("Device '%s' cannot be both 'tmp' and 'swap'. Ignoring.", name);
                return -EINVAL;
        }

        e = unit_name_escape(name);
        if (!e)
                return log_oom();

        n = unit_name_build("systemd-cryptsetup", e, ".service");
        if (!n)
                return log_oom();

        p = strjoin(arg_dest, "/", n, NULL);
        if (!p)
                return log_oom();

        u = fstab_node_to_udev_node(device);
        if (!u)
                return log_oom();

        d = unit_name_from_path(u, ".device");
        if (!d)
                return log_oom();

        f = fopen(p, "wxe");
        if (!f) {
                log_error("Failed to create unit file %s: %m", p);
                return -errno;
        }

        fputs(
                "# Automatically generated by systemd-cryptsetup-generator\n\n"
                "[Unit]\n"
                "Description=Cryptography Setup for %I\n"
                "Documentation=man:crypttab(5) man:systemd-cryptsetup-generator(8) man:systemd-cryptsetup@.service(8)\n"
                "SourcePath=/etc/crypttab\n"
                "DefaultDependencies=no\n"
                "Conflicts=umount.target\n"
                "BindsTo=dev-mapper-%i.device\n"
                "IgnoreOnIsolate=true\n"
                "After=cryptsetup-pre.target\n",
                f);

        if (!nofail)
                fprintf(f,
                        "Before=cryptsetup.target\n");

        if (password) {
                if (STR_IN_SET(password, "/dev/urandom", "/dev/random", "/dev/hw_random"))
                        fputs("After=systemd-random-seed.service\n", f);
                else if (!streq(password, "-") && !streq(password, "none")) {
                        _cleanup_free_ char *uu;

                        uu = fstab_node_to_udev_node(password);
                        if (!uu)
                                return log_oom();

                        if (!path_equal(uu, "/dev/null")) {

                                if (is_device_path(uu)) {
                                        _cleanup_free_ char *dd;

                                        dd = unit_name_from_path(uu, ".device");
                                        if (!dd)
                                                return log_oom();

                                        fprintf(f, "After=%1$s\nRequires=%1$s\n", dd);
                                } else
                                        fprintf(f, "RequiresMountsFor=%s\n", password);
                        }
                }
        }

        if (is_device_path(u))
                fprintf(f,
                        "BindsTo=%s\n"
                        "After=%s\n"
                        "Before=umount.target\n",
                        d, d);
        else
                fprintf(f,
                        "RequiresMountsFor=%s\n",
                        u);

        r = generator_write_timeouts(arg_dest, device, name, options, &filtered);
        if (r < 0)
                return r;

        fprintf(f,
                "\n[Service]\n"
                "Type=oneshot\n"
                "RemainAfterExit=yes\n"
                "TimeoutSec=0\n" /* the binary handles timeouts anyway */
                "ExecStart=" SYSTEMD_CRYPTSETUP_PATH " attach '%s' '%s' '%s' '%s'\n"
                "ExecStop=" SYSTEMD_CRYPTSETUP_PATH " detach '%s'\n",
                name, u, strempty(password), strempty(filtered),
                name);

        if (tmp)
                fprintf(f,
                        "ExecStartPost=/sbin/mke2fs '/dev/mapper/%s'\n",
                        name);

        if (swap)
                fprintf(f,
                        "ExecStartPost=/sbin/mkswap '/dev/mapper/%s'\n",
                        name);

        fflush(f);
        if (ferror(f)) {
                log_error("Failed to write file %s: %m", p);
                return -errno;
        }

        from = strappenda("../", n);

        if (!noauto) {

                to = strjoin(arg_dest, "/", d, ".wants/", n, NULL);
                if (!to)
                        return log_oom();

                mkdir_parents_label(to, 0755);
                if (symlink(from, to) < 0) {
                        log_error("Failed to create symlink %s: %m", to);
                        return -errno;
                }

                free(to);
                if (!nofail)
                        to = strjoin(arg_dest, "/cryptsetup.target.requires/", n, NULL);
                else
                        to = strjoin(arg_dest, "/cryptsetup.target.wants/", n, NULL);
                if (!to)
                        return log_oom();

                mkdir_parents_label(to, 0755);
                if (symlink(from, to) < 0) {
                        log_error("Failed to create symlink %s: %m", to);
                        return -errno;
                }
        }

        free(to);
        to = strjoin(arg_dest, "/dev-mapper-", e, ".device.requires/", n, NULL);
        if (!to)
                return log_oom();

        mkdir_parents_label(to, 0755);
        if (symlink(from, to) < 0) {
                log_error("Failed to create symlink %s: %m", to);
                return -errno;
        }

        if (!noauto && !nofail) {
                _cleanup_free_ char *dmname;
                dmname = strjoin("dev-mapper-", e, ".device", NULL);
                if (!dmname)
                        return log_oom();

                r = write_drop_in(arg_dest, dmname, 90, "device-timeout",
                                  "# Automatically generated by systemd-cryptsetup-generator \n\n"
                                  "[Unit]\nJobTimeoutSec=0");
                if (r < 0) {
                        log_error("Failed to write device drop-in: %s", strerror(-r));
                        return r;
                }
        }

        return 0;
}

static int parse_proc_cmdline_item(const char *key, const char *value) {
        int r;

        if (STR_IN_SET(key, "luks", "rd.luks") && value) {

                r = parse_boolean(value);
                if (r < 0)
                        log_warning("Failed to parse luks switch %s. Ignoring.", value);
                else
                        arg_enabled = r;

        } else if (STR_IN_SET(key, "luks.crypttab", "rd.luks.crypttab") && value) {

                r = parse_boolean(value);
                if (r < 0)
                        log_warning("Failed to parse luks crypttab switch %s. Ignoring.", value);
                else
                        arg_read_crypttab = r;

        } else if (STR_IN_SET(key, "luks.uuid", "rd.luks.uuid") && value) {

                if (strv_extend(&arg_disks, value) < 0)
                        return log_oom();

        } else if (STR_IN_SET(key, "luks.options", "rd.luks.options") && value) {

                if (strv_extend(&arg_options, value) < 0)
                        return log_oom();

        } else if (STR_IN_SET(key, "luks.key", "rd.luks.key") && value) {

                free(arg_keyfile);
                arg_keyfile = strdup(value);
                if (!arg_keyfile)
                        return log_oom();

        }

        return 0;
}

int main(int argc, char *argv[]) {
        _cleanup_strv_free_ char **disks_done = NULL;
        _cleanup_fclose_ FILE *f = NULL;
        unsigned n = 0;
        int r = EXIT_FAILURE, r2 = EXIT_FAILURE;
        char **i;

        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);

        if (parse_proc_cmdline(parse_proc_cmdline_item) < 0)
                goto cleanup;

        if (!arg_enabled) {
                r = r2 = EXIT_SUCCESS;
                goto cleanup;
        }

        strv_uniq(arg_disks);

        if (arg_read_crypttab) {
                struct stat st;

                f = fopen("/etc/crypttab", "re");
                if (!f) {
                        if (errno == ENOENT)
                                r = EXIT_SUCCESS;
                        else
                                log_error("Failed to open /etc/crypttab: %m");

                        goto next;
                }

                if (fstat(fileno(f), &st) < 0) {
                        log_error("Failed to stat /etc/crypttab: %m");
                        goto next;
                }

                /* If we readd support for specifying passphrases
                 * directly in crypttabe we should upgrade the warning
                 * below, though possibly only if a passphrase is
                 * specified directly. */
                if (st.st_mode & 0005)
                        log_debug("/etc/crypttab is world-readable. This is usually not a good idea.");

                for (;;) {
                        char line[LINE_MAX], *l;
                        _cleanup_free_ char *name = NULL, *device = NULL, *password = NULL, *options = NULL;
                        int k;

                        if (!fgets(line, sizeof(line), f))
                                break;

                        n++;

                        l = strstrip(line);
                        if (*l == '#' || *l == 0)
                                continue;

                        k = sscanf(l, "%ms %ms %ms %ms", &name, &device, &password, &options);
                        if (k < 2 || k > 4) {
                                log_error("Failed to parse /etc/crypttab:%u, ignoring.", n);
                                continue;
                        }

                        /*
                          If options are specified on the kernel command line, let them override
                          the ones from crypttab.
                        */
                        STRV_FOREACH(i, arg_options) {
                                _cleanup_free_ char *proc_uuid = NULL, *proc_options = NULL;
                                const char *p = *i;

                                k = sscanf(p, "%m[0-9a-fA-F-]=%ms", &proc_uuid, &proc_options);
                                if (k == 2 && streq(proc_uuid, device + 5)) {
                                        free(options);
                                        options = strdup(p);
                                        if (!options) {
                                                log_oom();
                                                goto cleanup;
                                        }
                                }
                        }

                        if (arg_disks) {
                                /*
                                  If luks UUIDs are specified on the kernel command line, use them as a filter
                                  for /etc/crypttab and only generate units for those.
                                */
                                STRV_FOREACH(i, arg_disks) {
                                        _cleanup_free_ char *proc_device = NULL, *proc_name = NULL;
                                        const char *p = *i;

                                        if (startswith(p, "luks-"))
                                                p += 5;

                                        proc_name = strappend("luks-", p);
                                        proc_device = strappend("UUID=", p);

                                        if (!proc_name || !proc_device) {
                                                log_oom();
                                                goto cleanup;
                                        }

                                        if (streq(proc_device, device) || streq(proc_name, name)) {
                                                if (create_disk(name, device, password, options) < 0)
                                                        goto cleanup;

                                                if (strv_extend(&disks_done, p) < 0) {
                                                        log_oom();
                                                        goto cleanup;
                                                }
                                        }
                                }
                        } else if (create_disk(name, device, password, options) < 0)
                                goto cleanup;

                }
        }

        r = EXIT_SUCCESS;

next:
        STRV_FOREACH(i, arg_disks) {
                /*
                  Generate units for those UUIDs, which were specified
                  on the kernel command line and not yet written.
                */

                _cleanup_free_ char *name = NULL, *device = NULL, *options = NULL;
                const char *p = *i;

                if (startswith(p, "luks-"))
                        p += 5;

                if (strv_contains(disks_done, p))
                        continue;

                name = strappend("luks-", p);
                device = strappend("UUID=", p);

                if (!name || !device) {
                        log_oom();
                        goto cleanup;
                }

                if (arg_options) {
                        /*
                          If options are specified on the kernel command line, use them.
                        */
                        char **j;

                        STRV_FOREACH(j, arg_options) {
                                _cleanup_free_ char *proc_uuid = NULL, *proc_options = NULL;
                                const char *s = *j;
                                int k;

                                k = sscanf(s, "%m[0-9a-fA-F-]=%ms", &proc_uuid, &proc_options);
                                if (k == 2) {
                                        if (streq(proc_uuid, device + 5)) {
                                                free(options);
                                                options = proc_options;
                                                proc_options = NULL;
                                        }
                                } else if (!options) {
                                        /*
                                          Fall back to options without a specified UUID
                                        */
                                        options = strdup(s);
                                        if (!options) {
                                                log_oom();
                                                goto cleanup;
                                        };
                                }
                        }
                }

                if (!options) {
                        options = strdup("timeout=0");
                        if (!options) {
                                log_oom();
                                goto cleanup;
                        }
                }

                if (create_disk(name, device, arg_keyfile, options) < 0)
                        goto cleanup;
        }

        r2 = EXIT_SUCCESS;

cleanup:
        strv_free(arg_disks);
        strv_free(arg_options);
        free(arg_keyfile);

        return r != EXIT_SUCCESS ? r : r2;
}