[systemd-devel] [PATCH] add keyhandler support to cryptsetup

Benjamin SANS bs at ziirish.info
Thu Mar 13 10:29:55 PDT 2014


Hi list,

Following this thread: http://lists.freedesktop.org/archives/systemd-devel/2012-July/005835.html, 
I understand you don't want to support a "keyscript" option as implemented in
that patch.

So I wrote these few lines to support a new "keyhandler" option (so that you
don't necessary need it to be a script, it can be whatever you want) and
implemented a new crypt-keyhandler-agent. 
The keyhandler takes the third field of the crypttab record as argument (the
key_file)
Actually, I just enhanced the existing tty-ask-password-agent. 
The goal is to have a fallback with the "manual" ask-password method.

For instance, I want my keyhandler to read the keyfile out of a usb key. If my
usb key is not present I can fallback to the password method.

Would a patch as below be acceptable?
I didn't tested it yet. I just want to know if it is the right way to do it or
if I misunderstood the discussion.

Thanks

-- 
Benjamin SANS

diff --git a/src/crypt-keyhandler-agent/Makefile b/src/crypt-keyhandler-agent/Makefile
new file mode 120000
index 0000000..d0b0e8e
--- /dev/null
+++ b/src/crypt-keyhandler-agent/Makefile
@@ -0,0 +1 @@
+../Makefile
\ No newline at end of file
diff --git a/src/crypt-keyhandler-agent/crypt-keyhandler-agent.c b/src/crypt-keyhandler-agent/crypt-keyhandler-agent.c
new file mode 100644
index 0000000..1036347
--- /dev/null
+++ b/src/crypt-keyhandler-agent/crypt-keyhandler-agent.c
@@ -0,0 +1,808 @@
+/*-*- 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 <stdbool.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <stddef.h>
+#include <sys/poll.h>
+#include <sys/inotify.h>
+#include <unistd.h>
+#include <getopt.h>
+#include <sys/signalfd.h>
+#include <fcntl.h>
+
+#include "util.h"
+#include "mkdir.h"
+#include "path-util.h"
+#include "conf-parser.h"
+#include "utmp-wtmp.h"
+#include "socket-util.h"
+#include "ask-password-api.h"
+#include "strv.h"
+#include "build.h"
+
+static enum {
+        ACTION_LIST,
+        ACTION_QUERY,
+        ACTION_WATCH,
+        ACTION_WALL
+} arg_action = ACTION_QUERY;
+
+static bool arg_plymouth = false;
+static bool arg_console = false;
+
+static int ask_password_plymouth(
+                const char *message,
+                usec_t until,
+                const char *flag_file,
+                bool accept_cached,
+                char ***_passphrases) {
+
+        int fd = -1, notify = -1;
+        union sockaddr_union sa = {};
+        char *packet = NULL;
+        ssize_t k;
+        int r, n;
+        struct pollfd pollfd[2] = {};
+        char buffer[LINE_MAX];
+        size_t p = 0;
+        enum {
+                POLL_SOCKET,
+                POLL_INOTIFY
+        };
+
+        assert(_passphrases);
+
+        if (flag_file) {
+                if ((notify = inotify_init1(IN_CLOEXEC|IN_NONBLOCK)) < 0) {
+                        r = -errno;
+                        goto finish;
+                }
+
+                if (inotify_add_watch(notify, flag_file, IN_ATTRIB /* for the link count */) < 0) {
+                        r = -errno;
+                        goto finish;
+                }
+        }
+
+        if ((fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0)) < 0) {
+                r = -errno;
+                goto finish;
+        }
+
+        sa.sa.sa_family = AF_UNIX;
+        strncpy(sa.un.sun_path+1, "/org/freedesktop/plymouthd", sizeof(sa.un.sun_path)-1);
+        if (connect(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + 1 + strlen(sa.un.sun_path+1)) < 0) {
+                log_error("Failed to connect to Plymouth: %m");
+                r = -errno;
+                goto finish;
+        }
+
+        if (accept_cached) {
+                packet = strdup("c");
+                n = 1;
+        } else
+                asprintf(&packet, "*\002%c%s%n", (int) (strlen(message) + 1), message, &n);
+
+        if (!packet) {
+                r = -ENOMEM;
+                goto finish;
+        }
+
+        if ((k = loop_write(fd, packet, n+1, true)) != n+1) {
+                r = k < 0 ? (int) k : -EIO;
+                goto finish;
+        }
+
+        pollfd[POLL_SOCKET].fd = fd;
+        pollfd[POLL_SOCKET].events = POLLIN;
+        pollfd[POLL_INOTIFY].fd = notify;
+        pollfd[POLL_INOTIFY].events = POLLIN;
+
+        for (;;) {
+                int sleep_for = -1, j;
+
+                if (until > 0) {
+                        usec_t y;
+
+                        y = now(CLOCK_MONOTONIC);
+
+                        if (y > until) {
+                                r = -ETIME;
+                                goto finish;
+                        }
+
+                        sleep_for = (int) ((until - y) / USEC_PER_MSEC);
+                }
+
+                if (flag_file)
+                        if (access(flag_file, F_OK) < 0) {
+                                r = -errno;
+                                goto finish;
+                        }
+
+                if ((j = poll(pollfd, notify > 0 ? 2 : 1, sleep_for)) < 0) {
+
+                        if (errno == EINTR)
+                                continue;
+
+                        r = -errno;
+                        goto finish;
+                } else if (j == 0) {
+                        r = -ETIME;
+                        goto finish;
+                }
+
+                if (notify > 0 && pollfd[POLL_INOTIFY].revents != 0)
+                        flush_fd(notify);
+
+                if (pollfd[POLL_SOCKET].revents == 0)
+                        continue;
+
+                if ((k = read(fd, buffer + p, sizeof(buffer) - p)) <= 0) {
+                        r = k < 0 ? -errno : -EIO;
+                        goto finish;
+                }
+
+                p += k;
+
+                if (p < 1)
+                        continue;
+
+                if (buffer[0] == 5) {
+
+                        if (accept_cached) {
+                                /* Hmm, first try with cached
+                                 * passwords failed, so let's retry
+                                 * with a normal password request */
+                                free(packet);
+                                packet = NULL;
+
+                                if (asprintf(&packet, "*\002%c%s%n", (int) (strlen(message) + 1), message, &n) < 0) {
+                                        r = -ENOMEM;
+                                        goto finish;
+                                }
+
+                                if ((k = loop_write(fd, packet, n+1, true)) != n+1) {
+                                        r = k < 0 ? (int) k : -EIO;
+                                        goto finish;
+                                }
+
+                                accept_cached = false;
+                                p = 0;
+                                continue;
+                        }
+
+                        /* No password, because UI not shown */
+                        r = -ENOENT;
+                        goto finish;
+
+                } else if (buffer[0] == 2 || buffer[0] == 9) {
+                        uint32_t size;
+                        char **l;
+
+                        /* One ore more answers */
+                        if (p < 5)
+                                continue;
+
+                        memcpy(&size, buffer+1, sizeof(size));
+                        size = le32toh(size);
+                        if (size+5 > sizeof(buffer)) {
+                                r = -EIO;
+                                goto finish;
+                        }
+
+                        if (p-5 < size)
+                                continue;
+
+                        if (!(l = strv_parse_nulstr(buffer + 5, size))) {
+                                r = -ENOMEM;
+                                goto finish;
+                        }
+
+                        *_passphrases = l;
+                        break;
+
+                } else {
+                        /* Unknown packet */
+                        r = -EIO;
+                        goto finish;
+                }
+        }
+
+        r = 0;
+
+finish:
+        if (notify >= 0)
+                close_nointr_nofail(notify);
+
+        if (fd >= 0)
+                close_nointr_nofail(fd);
+
+        free(packet);
+
+        return r;
+}
+
+static int parse_password(const char *filename, char **wall) {
+        char *socket_name = NULL, *message = NULL, *packet = NULL, keyhandler = NULL, keyopts = NULL;
+        uint64_t not_after = 0;
+        unsigned pid = 0;
+        int socket_fd = -1;
+        bool accept_cached = false;
+
+        const ConfigTableItem items[] = {
+                { "Ask", "Socket",       config_parse_string,   0, &socket_name   },
+                { "Ask", "NotAfter",     config_parse_uint64,   0, &not_after     },
+                { "Ask", "Message",      config_parse_string,   0, &message       },
+                { "Ask", "PID",          config_parse_unsigned, 0, &pid           },
+                { "Ask", "AcceptCached", config_parse_bool,     0, &accept_cached },
+                { "Ask", "KeyHandler",   config_parse_string,   0, &keyhandler    },
+                { "Ask", "KeyOpts",      config_parse_string,   0, &keyopts       },
+                { NULL, NULL, NULL, 0, NULL }
+        };
+
+        FILE *f;
+        int r;
+
+        assert(filename);
+
+        f = fopen(filename, "re");
+        if (!f) {
+                if (errno == ENOENT)
+                        return 0;
+
+                log_error("open(%s): %m", filename);
+                return -errno;
+        }
+
+        r = config_parse(NULL, filename, f, NULL, config_item_table_lookup, (void*) items, true, false, NULL);
+        if (r < 0) {
+                log_error("Failed to parse password file %s: %s", filename, strerror(-r));
+                goto finish;
+        }
+
+        if (!socket_name) {
+                log_error("Invalid password file %s", filename);
+                r = -EBADMSG;
+                goto finish;
+        }
+
+        if (not_after > 0) {
+                if (now(CLOCK_MONOTONIC) > not_after) {
+                        r = 0;
+                        goto finish;
+                }
+        }
+
+        if (pid > 0 && !pid_is_alive(pid)) {
+                r = 0;
+                goto finish;
+        }
+
+        if (arg_action == ACTION_LIST)
+                printf("'%s' (PID %u)\n", message, pid);
+        else if (arg_action == ACTION_WALL) {
+                char *_wall;
+
+                if (asprintf(&_wall,
+                             "%s%sPassword entry required for \'%s\' (PID %u).\r\n"
+                             "Please enter password with the systemd-tty-ask-password-agent tool!",
+                             *wall ? *wall : "",
+                             *wall ? "\r\n\r\n" : "",
+                             message,
+                             pid) < 0) {
+                        r = log_oom();
+                        goto finish;
+                }
+
+                free(*wall);
+                *wall = _wall;
+        } else {
+                union {
+                        struct sockaddr sa;
+                        struct sockaddr_un un;
+                } sa = {};
+                size_t packet_length = 0;
+
+                assert(arg_action == ACTION_QUERY ||
+                       arg_action == ACTION_WATCH);
+
+                if (access(socket_name, W_OK) < 0) {
+
+                        if (arg_action == ACTION_QUERY)
+                                log_info("Not querying '%s' (PID %u), lacking privileges.", message, pid);
+
+                        r = 0;
+                        goto finish;
+                }
+
+                if (keyhandler) {
+                        char temp[] = "/run/systemd/ask-password/tmp.XXXXXX";
+                        int fd = -1;
+                        pid_t pid;
+
+                        mkdir_p_label("/run/systemd/ask-password", 0755);
+
+                        fd = mkostemp_safe(temp, O_WRONLY|O_CLOEXEC);
+                        if (fd < 0) {
+                                log_error("Failed to create password file: %m");
+                                r = -errno;
+                                goto finish;
+                        }
+
+                        fchmod(fd, 0644);
+
+                        pid = fork();
+
+                        if (pid < 0) {
+                                log_error("Failed to fork: %m");
+                                r = -errno;
+                                goto finish;
+                        } else if (pid > 0) {
+                                waitpid(pid, NULL, 0);
+                                
+                                /* send back the temporary filename that now contains our key */
+                                packet_length = 2 + strlen(temp);
+
+                                if (!(packet = new(char, packet_length)))
+                                        r = -ENOMEM;
+                                else {
+                                        char *d;
+                                        packet[0] = '+';
+                                        d = packet+1;
+                                        d = stpcpy(d, temp) + 1;
+                                }
+                        } else if (pid == 0) {
+                                /* launch the keyhandler programm and redirect its output to our temporary file */
+                                const char *args[3];
+
+                                if (dup2(fd, STDOUT_FILENO) < 0)
+                                        _exit(EXIT_FAILURE);
+
+                                args[0] = keyhandler;
+                                args[1] = keyopts;
+                                args[2] = NULL;
+
+                                execv(args[0], (char **)args);
+                                _exit(EXIT_FAILURE);
+                        }
+                } else if (arg_plymouth) {
+                        _cleanup_strv_free_ char **passwords = NULL;
+
+                        if ((r = ask_password_plymouth(message, not_after, filename, accept_cached, &passwords)) >= 0) {
+                                char **p;
+
+                                packet_length = 1;
+                                STRV_FOREACH(p, passwords)
+                                        packet_length += strlen(*p) + 1;
+
+                                if (!(packet = new(char, packet_length)))
+                                        r = -ENOMEM;
+                                else {
+                                        char *d;
+
+                                        packet[0] = '+';
+                                        d = packet+1;
+
+                                        STRV_FOREACH(p, passwords)
+                                                d = stpcpy(d, *p) + 1;
+                                }
+                        }
+
+                } else {
+                        int tty_fd = -1;
+                        char *password = NULL;
+
+                        if (arg_console)
+                                if ((tty_fd = acquire_terminal("/dev/console", false, false, false, (usec_t) -1)) < 0) {
+                                        r = tty_fd;
+                                        goto finish;
+                                }
+
+                        r = ask_password_tty(message, not_after, filename, &password);
+
+                        if (arg_console) {
+                                close_nointr_nofail(tty_fd);
+                                release_terminal();
+                        }
+
+                        if (r >= 0) {
+                                packet_length = 1+strlen(password)+1;
+                                if (!(packet = new(char, packet_length)))
+                                        r = -ENOMEM;
+                                else {
+                                        packet[0] = '+';
+                                        strcpy(packet+1, password);
+                                }
+
+                                free(password);
+                        }
+                }
+
+                if (r == -ETIME || r == -ENOENT) {
+                        /* If the query went away, that's OK */
+                        r = 0;
+                        goto finish;
+                }
+
+                if (r < 0) {
+                        log_error("Failed to query password: %s", strerror(-r));
+                        goto finish;
+                }
+
+                if ((socket_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0)) < 0) {
+                        log_error("socket(): %m");
+                        r = -errno;
+                        goto finish;
+                }
+
+                sa.un.sun_family = AF_UNIX;
+                strncpy(sa.un.sun_path, socket_name, sizeof(sa.un.sun_path));
+
+                if (sendto(socket_fd, packet, packet_length, MSG_NOSIGNAL, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(socket_name)) < 0) {
+                        log_error("Failed to send: %m");
+                        r = -errno;
+                        goto finish;
+                }
+        }
+
+finish:
+        fclose(f);
+
+        if (socket_fd >= 0)
+                close_nointr_nofail(socket_fd);
+
+        free(packet);
+        free(socket_name);
+        free(message);
+
+        return r;
+}
+
+static int wall_tty_block(void) {
+        char *p;
+        int fd, r;
+        dev_t devnr;
+
+        r = get_ctty_devnr(0, &devnr);
+        if (r < 0)
+                return -r;
+
+        if (asprintf(&p, "/run/systemd/ask-password-block/%u:%u", major(devnr), minor(devnr)) < 0)
+                return -ENOMEM;
+
+        mkdir_parents_label(p, 0700);
+        mkfifo(p, 0600);
+
+        fd = open(p, O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
+        free(p);
+
+        if (fd < 0)
+                return -errno;
+
+        return fd;
+}
+
+static bool wall_tty_match(const char *path) {
+        int fd, k;
+        char *p;
+        struct stat st;
+
+        if (path_is_absolute(path))
+                k = lstat(path, &st);
+        else {
+                if (asprintf(&p, "/dev/%s", path) < 0)
+                        return true;
+
+                k = lstat(p, &st);
+                free(p);
+        }
+
+        if (k < 0)
+                return true;
+
+        if (!S_ISCHR(st.st_mode))
+                return true;
+
+        /* We use named pipes to ensure that wall messages suggesting
+         * password entry are not printed over password prompts
+         * already shown. We use the fact here that opening a pipe in
+         * non-blocking mode for write-only will succeed only if
+         * there's some writer behind it. Using pipes has the
+         * advantage that the block will automatically go away if the
+         * process dies. */
+
+        if (asprintf(&p, "/run/systemd/ask-password-block/%u:%u", major(st.st_rdev), minor(st.st_rdev)) < 0)
+                return true;
+
+        fd = open(p, O_WRONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
+        free(p);
+
+        if (fd < 0)
+                return true;
+
+        /* What, we managed to open the pipe? Then this tty is filtered. */
+        close_nointr_nofail(fd);
+        return false;
+}
+
+static int show_passwords(void) {
+        DIR *d;
+        struct dirent *de;
+        int r = 0;
+
+        if (!(d = opendir("/run/systemd/ask-password"))) {
+                if (errno == ENOENT)
+                        return 0;
+
+                log_error("opendir(): %m");
+                return -errno;
+        }
+
+        while ((de = readdir(d))) {
+                char *p;
+                int q;
+                char *wall;
+
+                /* We only support /dev on tmpfs, hence we can rely on
+                 * d_type to be reliable */
+
+                if (de->d_type != DT_REG)
+                        continue;
+
+                if (ignore_file(de->d_name))
+                        continue;
+
+                if (!startswith(de->d_name, "ask."))
+                        continue;
+
+                if (!(p = strappend("/run/systemd/ask-password/", de->d_name))) {
+                        r = log_oom();
+                        goto finish;
+                }
+
+                wall = NULL;
+                if ((q = parse_password(p, &wall)) < 0)
+                        r = q;
+
+                free(p);
+
+                if (wall) {
+                        utmp_wall(wall, wall_tty_match);
+                        free(wall);
+                }
+        }
+
+finish:
+        if (d)
+                closedir(d);
+
+        return r;
+}
+
+static int watch_passwords(void) {
+        enum {
+                FD_INOTIFY,
+                FD_SIGNAL,
+                _FD_MAX
+        };
+
+        int notify = -1, signal_fd = -1, tty_block_fd = -1;
+        struct pollfd pollfd[_FD_MAX] = {};
+        sigset_t mask;
+        int r;
+
+        tty_block_fd = wall_tty_block();
+
+        mkdir_p_label("/run/systemd/ask-password", 0755);
+
+        if ((notify = inotify_init1(IN_CLOEXEC)) < 0) {
+                r = -errno;
+                goto finish;
+        }
+
+        if (inotify_add_watch(notify, "/run/systemd/ask-password", IN_CLOSE_WRITE|IN_MOVED_TO) < 0) {
+                r = -errno;
+                goto finish;
+        }
+
+        assert_se(sigemptyset(&mask) == 0);
+        sigset_add_many(&mask, SIGINT, SIGTERM, -1);
+        assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
+
+        if ((signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
+                log_error("signalfd(): %m");
+                r = -errno;
+                goto finish;
+        }
+
+        pollfd[FD_INOTIFY].fd = notify;
+        pollfd[FD_INOTIFY].events = POLLIN;
+        pollfd[FD_SIGNAL].fd = signal_fd;
+        pollfd[FD_SIGNAL].events = POLLIN;
+
+        for (;;) {
+                if ((r = show_passwords()) < 0)
+                        log_error("Failed to show password: %s", strerror(-r));
+
+                if (poll(pollfd, _FD_MAX, -1) < 0) {
+
+                        if (errno == EINTR)
+                                continue;
+
+                        r = -errno;
+                        goto finish;
+                }
+
+                if (pollfd[FD_INOTIFY].revents != 0)
+                        flush_fd(notify);
+
+                if (pollfd[FD_SIGNAL].revents != 0)
+                        break;
+        }
+
+        r = 0;
+
+finish:
+        if (notify >= 0)
+                close_nointr_nofail(notify);
+
+        if (signal_fd >= 0)
+                close_nointr_nofail(signal_fd);
+
+        if (tty_block_fd >= 0)
+                close_nointr_nofail(tty_block_fd);
+
+        return r;
+}
+
+static int help(void) {
+
+        printf("%s [OPTIONS...]\n\n"
+               "Process system password requests.\n\n"
+               "  -h --help             Show this help\n"
+               "     --version          Show package version\n"
+               "     --list             Show pending password requests\n"
+               "     --query            Process pending password requests\n"
+               "     --watch            Continuously process password requests\n"
+               "     --wall             Continuously forward password requests to wall\n"
+               "     --plymouth         Ask question with Plymouth instead of on TTY\n"
+               "     --console          Ask question on /dev/console instead of current TTY\n"
+               "     --script=<path>    Script to run before falling back to another ask mode\n",
+               program_invocation_short_name);
+
+        return 0;
+}
+
+static int parse_argv(int argc, char *argv[]) {
+
+        enum {
+                ARG_LIST = 0x100,
+                ARG_QUERY,
+                ARG_WATCH,
+                ARG_WALL,
+                ARG_PLYMOUTH,
+                ARG_CONSOLE,
+                ARG_VERSION,
+        };
+
+        static const struct option options[] = {
+                { "help",     no_argument,       NULL, 'h'          },
+                { "version",  no_argument,       NULL, ARG_VERSION  },
+                { "list",     no_argument,       NULL, ARG_LIST     },
+                { "query",    no_argument,       NULL, ARG_QUERY    },
+                { "watch",    no_argument,       NULL, ARG_WATCH    },
+                { "wall",     no_argument,       NULL, ARG_WALL     },
+                { "plymouth", no_argument,       NULL, ARG_PLYMOUTH },
+                { "console",  no_argument,       NULL, ARG_CONSOLE  },
+                {}
+        };
+
+        int c;
+
+        assert(argc >= 0);
+        assert(argv);
+
+        while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0) {
+
+                switch (c) {
+
+                case 'h':
+                        return help();
+
+                case ARG_VERSION:
+                        puts(PACKAGE_STRING);
+                        puts(SYSTEMD_FEATURES);
+                        return 0;
+
+                case ARG_LIST:
+                        arg_action = ACTION_LIST;
+                        break;
+
+                case ARG_QUERY:
+                        arg_action = ACTION_QUERY;
+                        break;
+
+                case ARG_WATCH:
+                        arg_action = ACTION_WATCH;
+                        break;
+
+                case ARG_WALL:
+                        arg_action = ACTION_WALL;
+                        break;
+
+                case ARG_PLYMOUTH:
+                        arg_plymouth = true;
+                        break;
+
+                case ARG_CONSOLE:
+                        arg_console = true;
+                        break;
+
+                case '?':
+                        return -EINVAL;
+
+                default:
+                        assert_not_reached("Unhandled option");
+                }
+        }
+
+        if (optind != argc) {
+                help();
+                return -EINVAL;
+        }
+
+        return 1;
+}
+
+int main(int argc, char *argv[]) {
+        int r;
+
+        log_set_target(LOG_TARGET_AUTO);
+        log_parse_environment();
+        log_open();
+
+        umask(0022);
+
+        if ((r = parse_argv(argc, argv)) <= 0)
+                goto finish;
+
+        if (arg_console) {
+                setsid();
+                release_terminal();
+        }
+
+        if (arg_action == ACTION_WATCH ||
+            arg_action == ACTION_WALL)
+                r = watch_passwords();
+        else
+                r = show_passwords();
+
+        if (r < 0)
+                log_error("Error: %s", strerror(-r));
+
+finish:
+        return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
+}
diff --git a/src/cryptsetup/cryptsetup.c b/src/cryptsetup/cryptsetup.c
index 4dc2b08..110f11d 100644
--- a/src/cryptsetup/cryptsetup.c
+++ b/src/cryptsetup/cryptsetup.c
@@ -43,6 +43,7 @@ static int arg_key_slot = CRYPT_ANY_SLOT;
 static unsigned arg_keyfile_size = 0;
 static unsigned arg_keyfile_offset = 0;
 static char *arg_hash = NULL;
+static char *opt_keyhandler = NULL;
 static unsigned arg_tries = 3;
 static bool arg_readonly = false;
 static bool arg_verify = false;
@@ -129,6 +130,23 @@ static int parse_one_option(const char *option) {
                 free(arg_hash);
                 arg_hash = t;
 
+        } else if (startswith(option, "keyhandler=")) {
+                char *t;
+
+                if (!option[11] || !path_is_absolute(option+11)) {
+                        log_error("keyhandler= path is invalid, ignoring.");
+                        free(opt_keyhandler);
+                        opt_keyhandler = NULL;
+                        return 0;
+                }
+
+                t = strdup(option+11);
+                if (!t)
+                        return log_oom();
+
+                free(opt_keyhandler);
+                opt_keyhandler = t;
+
         } else if (startswith(option, "tries=")) {
 
                 if (safe_atou(option+6, &arg_tries) < 0) {
@@ -363,7 +381,8 @@ static int attach_luks_or_plain(struct crypt_device *cd,
                                 const char *name,
                                 const char *key_file,
                                 char **passwords,
-                                uint32_t flags) {
+                                uint32_t flagsi,
+                                int tries) {
         int r = 0;
         bool pass_volume_key = false;
 
@@ -430,10 +449,20 @@ static int attach_luks_or_plain(struct crypt_device *cd,
                  crypt_get_volume_key_size(cd)*8,
                  crypt_get_device_name(cd));
 
+        if (opt_keyhandler && tries == 0)
+                key_file = passwords[0];
+
         if (key_file) {
-                r = crypt_activate_by_keyfile_offset(cd, name, arg_key_slot,
-                                                     key_file, arg_keyfile_size,
-                                                     arg_keyfile_offset, flags);
+                r = crypt_activate_by_keyfile_offset(cd, name, opt_key_slot,
+                                                     key_file, opt_keyfile_size,
+                                                     opt_keyfile_offset, flags);
+
+                /* Remove the temporary file created by our agent as it contains our key! */
+                if (opt_keyhandler && tries == 0) {
+                        unlink(key_file);
+                        key_file = NULL;
+                }
+                        
                 if (r < 0) {
                         log_error("Failed to activate with key file '%s': %s", key_file, strerror(-r));
                         return -EAGAIN;
@@ -502,6 +531,7 @@ int main(int argc, char *argv[]) {
                         goto finish;
                 }
 
+                /*
                 if (argc >= 5 &&
                     argv[4][0] &&
                     !streq(argv[4], "-") &&
@@ -512,12 +542,26 @@ int main(int argc, char *argv[]) {
                         else
                                 key_file = argv[4];
                 }
+                */
 
                 if (argc >= 6 && argv[5][0] && !streq(argv[5], "-")) {
                         if (parse_options(argv[5]) < 0)
                                 goto finish;
                 }
 
+                if (argc >= 5) {                                                                                                                                                                                                         
+                        if (opt_keyhandler)
+                                key_file = argv[4]; /* used as arg to keyscript */
+                        else if (argv[4][0] &&
+                                 !streq(argv[4], "-") &&
+                                 !streq(argv[4], "none"))
+                                /* do nothing */;
+                        else if (!path_is_absolute(argv[4]))
+                                log_error("Password file path %s is not absolute. Ignoring.", argv[4]);
+                        else
+                                key_file = argv[4];
+                }
+
                 /* A delicious drop of snake oil */
                 mlockall(MCL_FUTURE);
 
@@ -581,6 +625,13 @@ int main(int argc, char *argv[]) {
                 for (tries = 0; arg_tries == 0 || tries < arg_tries; tries++) {
                         _cleanup_strv_free_ char **passwords = NULL;
 
+                        /* We only launch the handler once */
+                        if (opt_keyhandler && tries == 0) {
+                                passwords = strv_new(opt_keyhandler, key_file, NULL);
+                                /* We unset the key_file as it is only an argument to our handler and it has been copied above */
+                                key_file = NULL;
+                        }
+
                         if (!key_file) {
                                 k = get_password(name, until, tries == 0 && !arg_verify, &passwords);
                                 if (k == -EAGAIN)
@@ -592,7 +643,7 @@ int main(int argc, char *argv[]) {
                         if (streq_ptr(arg_type, CRYPT_TCRYPT))
                                 k = attach_tcrypt(cd, argv[2], key_file, passwords, flags);
                         else
-                                k = attach_luks_or_plain(cd, argv[2], key_file, passwords, flags);
+                                k = attach_luks_or_plain(cd, argv[2], key_file, passwords, flags, tries);
                         if (k >= 0)
                                 break;
                         else if (k == -EAGAIN) {
diff --git a/src/shared/ask-password-api.c b/src/shared/ask-password-api.c
index a328f14..cb24c00 100644
--- a/src/shared/ask-password-api.c
+++ b/src/shared/ask-password-api.c
@@ -370,6 +370,17 @@ int ask_password_agent(
         if (icon)
                 fprintf(f, "Icon=%s\n", icon);
 
+        /* We assume the keyhandler path and options are provided */
+        if (strv_length(*_passphrases) == 2) {
+                char **p = *_passphrases;
+                fprintf(f, "KeyHandler=%s\n"
+                           "KeyOpts=%s\n"
+                           p[0],
+                           p[1]);
+                strv_free(*_passphrases);
+                *_passphrases = NULL;
+        }
+
         fflush(f);
 
         if (ferror(f)) {
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