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-rw-r--r--udev/ykfde.c234
1 files changed, 147 insertions, 87 deletions
diff --git a/udev/ykfde.c b/udev/ykfde.c
index bf53eb4..9e0d1d3 100644
--- a/udev/ykfde.c
+++ b/udev/ykfde.c
@@ -5,7 +5,7 @@
* of the GNU General Public License, incorporated herein by reference.
*
* compile with:
- * $ gcc -o ykfde ykfde.c -lykpers-1 -lyubikey -liniparser
+ * $ gcc -o ykfde ykfde.c -liniparser -lkeyutils -lykpers-1 -lyubikey
*
* test with:
* $ systemd-ask-password --no-tty "Please enter passphrase for disk foobar..."
@@ -15,36 +15,49 @@
#include <errno.h>
#include <fcntl.h>
#include <stddef.h>
+#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
-#include <sys/inotify.h>
#include <sys/poll.h>
-#include <sys/signalfd.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/un.h>
#include <unistd.h>
+#include <iniparser.h>
+
+#include <keyutils.h>
+
#include <yubikey.h>
#include <ykpers-1/ykdef.h>
#include <ykpers-1/ykcore.h>
-#include <iniparser.h>
-
#include "../config.h"
-#define EVENT_SIZE (sizeof (struct inotify_event))
-#define EVENT_BUF_LEN (1024 * (EVENT_SIZE + 16))
-
-#define CHALLENGELEN 64
+/* Yubikey supports write of 64 byte challenge to slot,
+ * returns HMAC-SHA1 response.
+ *
+ * Lengths are defined in ykpers-1/ykdef.h:
+ * SHA1_MAX_BLOCK_SIZE 64
+ * SHA1_DIGEST_SIZE 20
+ *
+ * For passphrase we use hex encoded digest, that is
+ * twice the length of binary digest. */
+#define CHALLENGELEN SHA1_MAX_BLOCK_SIZE
#define RESPONSELEN SHA1_MAX_BLOCK_SIZE
#define PASSPHRASELEN SHA1_DIGEST_SIZE * 2
#define ASK_PATH "/run/systemd/ask-password/"
#define ASK_MESSAGE "Please enter passphrase for disk"
+#define PID_PATH "/run/ykfde.pid"
+
+void received_signal(int signal) {
+ /* Do nothing, just interrupt the sleep. */
+ return;
+}
static int send_on_socket(int fd, const char *socket_name, const void *packet, size_t size) {
union {
@@ -64,50 +77,121 @@ static int send_on_socket(int fd, const char *socket_name, const void *packet, s
return EXIT_SUCCESS;
}
-static int try_answer(char * ask_file, char * response) {
+static int try_answer(YK_KEY * yk, uint8_t slot, const char * ask_file, char * challenge) {
int8_t rc = EXIT_FAILURE;
dictionary * ini;
const char * ask_message, * ask_socket;
int fd_askpass;
+ char response[RESPONSELEN],
+ passphrase[PASSPHRASELEN + 1],
+ passphrase_askpass[PASSPHRASELEN + 2];
+ /* keyutils */
+ key_serial_t key;
+ void * payload = NULL;
+ size_t plen;
+
+ memset(response, 0, RESPONSELEN);
+ memset(passphrase, 0, PASSPHRASELEN + 1);
+ memset(passphrase_askpass, 0, PASSPHRASELEN + 2);
+
+ /* get second factor from key store
+ * if this fails it is not critical... possibly we just do not
+ * use second factor */
+ key = request_key("user", "ykfde-2f", NULL, 0);
+
+ if (key > 0) {
+ /* if we have a key id we have a key - so this should succeed */
+ if ((rc = keyctl_read_alloc(key, &payload)) < 0) {
+ perror("Failed reading payload from key");
+ goto out1;
+ }
+
+ /* we replace part of the challenge with the second factor */
+ plen = strlen(payload);
+ memcpy(challenge, payload, plen < CHALLENGELEN / 2 ? plen : CHALLENGELEN / 2);
+
+ free(payload);
+ }
+
+ /* do challenge/response and encode to hex */
+ if ((rc = yk_challenge_response(yk, slot, true,
+ CHALLENGELEN, (unsigned char *) challenge,
+ RESPONSELEN, (unsigned char *) response)) < 0) {
+ perror("yk_challenge_response() failed");
+ goto out1;
+ }
+ yubikey_hex_encode((char *) passphrase, (char *) response, SHA1_DIGEST_SIZE);
+
+ /* add key to kernel key store */
+ if ((key = add_key("user", "cryptsetup", passphrase, PASSPHRASELEN, KEY_SPEC_USER_KEYRING)) > 0) {
+ if (keyctl_set_timeout(key, 150) < 0)
+ perror("keyctl_set_timeout() failed");
+ } else
+ perror("add_key() failed");
+
+ /* key is placed, no ask file... quit here */
+ if (ask_file == NULL) {
+ rc = key > 0 ? EXIT_SUCCESS : EXIT_FAILURE;
+ goto out1;
+ }
- if ((ini = iniparser_load(ask_file)) == NULL)
+ if ((ini = iniparser_load(ask_file)) == NULL) {
+ rc = EXIT_FAILURE;
perror("cannot parse file");
+ goto out1;
+ }
ask_message = iniparser_getstring(ini, "Ask:Message", NULL);
- if (strncmp(ask_message, ASK_MESSAGE, strlen(ASK_MESSAGE)) != 0)
- goto out1;
+ if (strncmp(ask_message, ASK_MESSAGE, strlen(ASK_MESSAGE)) != 0) {
+ rc = EXIT_FAILURE;
+ goto out2;
+ }
- ask_socket = iniparser_getstring(ini, "Ask:Socket", NULL);
+ if ((ask_socket = iniparser_getstring(ini, "Ask:Socket", NULL)) == NULL) {
+ rc = EXIT_FAILURE;
+ perror("Could not get socket name");
+ goto out2;
+ }
+
+ sprintf(passphrase_askpass, "+%s", passphrase);
if ((fd_askpass = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0)) < 0) {
+ rc = EXIT_FAILURE;
perror("socket() failed");
- goto out1;
+ goto out2;
}
- if (send_on_socket(fd_askpass, ask_socket, response, PASSPHRASELEN + 1) < 0) {
+ if (send_on_socket(fd_askpass, ask_socket, passphrase_askpass, PASSPHRASELEN + 1) < 0) {
+ rc = EXIT_FAILURE;
perror("send_on_socket() failed");
- goto out2;
+ goto out3;
}
rc = EXIT_SUCCESS;
-out2:
+out3:
close(fd_askpass);
-out1:
+out2:
iniparser_freedict(ini);
+out1:
+ /* wipe response (cleartext password!) from memory */
+ memset(response, 0, RESPONSELEN);
+ memset(passphrase, 0, PASSPHRASELEN + 1);
+ memset(passphrase_askpass, 0, PASSPHRASELEN + 2);
+
return rc;
}
int main(int argc, char **argv) {
int8_t rc = EXIT_FAILURE;
+ FILE *pidfile;
/* Yubikey */
YK_KEY * yk;
uint8_t slot = SLOT_CHAL_HMAC2;
unsigned int serial = 0;
- char response[RESPONSELEN], passphrase[PASSPHRASELEN + 1], passphrase_askpass[PASSPHRASELEN + 2];
/* iniparser */
dictionary * ini;
char section_ykslot[10 /* unsigned int in char */ + 1 + sizeof(CONFYKSLOT) + 1];
@@ -118,17 +202,32 @@ int main(int argc, char **argv) {
/* read dir */
DIR * dir;
struct dirent * ent;
- /* inotify */
- struct inotify_event * event;
- int fd_inotify, watch, length, i = 0;
- char buffer[EVENT_BUF_LEN];
-#if DEBUG
+#ifdef DEBUG
/* reopening stderr to /dev/console may help debugging... */
- freopen("/dev/console", "w", stderr);
+ FILE * tmp = freopen("/dev/console", "w", stderr);
+ (void) tmp;
#endif
- memset(challenge, 0, CHALLENGELEN);
+ if ((pidfile = fopen(PID_PATH, "w")) != NULL) {
+ if (fprintf(pidfile, "%d", getpid()) < 0) {
+ rc = EXIT_FAILURE;
+ perror("Failed writing pid");
+ fclose(pidfile);
+ goto out10;
+ }
+ fclose(pidfile);
+ } else {
+ rc = EXIT_FAILURE;
+ perror("Failed opening pid file");
+ goto out10;
+ }
+
+ /* connect to signal */
+ signal(SIGUSR1, received_signal);
+
+ /* initialize static memory */
+ memset(challenge, 0, CHALLENGELEN + 1);
/* init and open first Yubikey */
if ((rc = yk_init()) < 0) {
@@ -143,7 +242,7 @@ int main(int argc, char **argv) {
}
/* read the serial number from key */
- if((rc = !yk_get_serial(yk, 0, 0, &serial)) < 0) {
+ if ((rc = yk_get_serial(yk, 0, 0, &serial)) < 0) {
perror("yk_get_serial() failed");
goto out30;
}
@@ -151,8 +250,10 @@ int main(int argc, char **argv) {
sprintf(challengefilename, CHALLENGEDIR "/challenge-%d", serial);
/* check if challenge file exists */
- if (access(challengefilename, R_OK) == -1)
+ if (access(challengefilename, R_OK) == -1) {
+ rc = EXIT_FAILURE;
goto out30;
+ }
/* read challenge from file */
if ((rc = challengefile = open(challengefilename, O_RDONLY)) < 0) {
@@ -162,10 +263,8 @@ int main(int argc, char **argv) {
if ((rc = read(challengefile, challenge, CHALLENGELEN)) < 0) {
perror("Failed reading challenge from file");
- goto out50;
+ goto out40;
}
- challengefile = close(challengefile);
- /* finished reading challenge */
/* try to read config file
* if anything here fails we do not care... slot 2 is the default */
@@ -193,75 +292,39 @@ int main(int argc, char **argv) {
iniparser_freedict(ini);
}
- memset(response, 0, RESPONSELEN);
- memset(passphrase, 0, PASSPHRASELEN + 1);
-
- /* do challenge/response and encode to hex */
- if ((rc = yk_challenge_response(yk, slot, true,
- CHALLENGELEN, (unsigned char *)challenge,
- RESPONSELEN, (unsigned char *)response)) < 0) {
- perror("yk_challenge_response() failed");
- goto out50;
- }
- yubikey_hex_encode((char *)passphrase, (char *)response, 20);
-
- sprintf(passphrase_askpass, "+%s", passphrase);
-
/* change to directory so we do not have to assemble complete/absolute path */
if ((rc = chdir(ASK_PATH)) != 0) {
perror("chdir() failed");
- goto out50;
- }
-
- /* creating the INOTIFY instance and add ASK_PATH directory into watch list */
- if ((rc = fd_inotify = inotify_init()) < 0) {
- perror("inotify_init() failed");
- goto out50;
+ goto out40;
}
- watch = inotify_add_watch(fd_inotify, ASK_PATH, IN_MOVED_TO);
-
- /* Is the request already there?
- * We do this AFTER setting up the inotify watch. This way we do not have race condition. */
+ /* Is the request already there? */
if ((dir = opendir(ASK_PATH)) != NULL) {
while ((ent = readdir(dir)) != NULL) {
if (strncmp(ent->d_name, "ask.", 4) == 0) {
- if ((rc = try_answer(ent->d_name, passphrase_askpass)) == EXIT_SUCCESS)
- goto out70;
+ if ((rc = try_answer(yk, slot, ent->d_name, challenge)) == EXIT_SUCCESS)
+ goto out50;
}
}
} else {
rc = EXIT_FAILURE;
perror ("opendir() failed");
- goto out60;
+ goto out50;
}
- /* read to determine the event change happens. Actually this read blocks until the change event occurs */
- if ((rc = length = read(fd_inotify, buffer, EVENT_BUF_LEN)) < 0) {
- perror("read() failed");
- goto out70;
- }
+ /* Wait for 90 seconds.
+ * The user has this time to enter his second factor, resulting in
+ * SIGUSR1 being sent to us. */
+ sleep(90);
- /* actually read return the list of change events happens.
- * Here, read the change event one by one and process it accordingly. */
- while (i < length) {
- event = (struct inotify_event *)&buffer[i];
- if (event->len > 0)
- if ((rc = try_answer(event->name, passphrase_askpass)) == EXIT_SUCCESS)
- goto out70;
- i += EVENT_SIZE + event->len;
- }
+ /* try again, but for key store this time */
+ rc = try_answer(yk, slot, NULL, challenge);
-out70:
+out50:
/* close dir */
closedir(dir);
-out60:
- /* remove inotify watch and remove file handle */
- inotify_rm_watch(fd_inotify, watch);
- close(fd_inotify);
-
-out50:
+out40:
/* close the challenge file */
if (challengefile)
close(challengefile);
@@ -270,12 +333,6 @@ out50:
unlink(challengefilename);
out30:
- /* wipe response (cleartext password!) from memory */
- memset(challenge, 0, CHALLENGELEN);
- memset(response, 0, RESPONSELEN);
- memset(passphrase, 0, PASSPHRASELEN + 1);
- memset(passphrase_askpass, 0, PASSPHRASELEN + 2);
-
/* close Yubikey */
if (yk_close_key(yk) < 0)
perror("yk_close_key() failed");
@@ -286,6 +343,9 @@ out20:
perror("yk_release() failed");
out10:
+ /* wipe challenge from memory */
+ memset(challenge, 0, CHALLENGELEN + 1);
+
return rc;
}
generated by cgit v1.2.3-70-g09d2 (git 2.47.1) at 2024-11-26 06:02:51 +0000