[pkg-cryptsetup-devel] Bug#742600: cryptsetup: add support for systemd to askpass

[David Härdeman]

Package: cryptsetup
Version: 2:1.6.4-4
Severity: wishlist
Tags: patch

Hi Jonas,

the following patch adds support for the systemd password agent API to
askpass (which means that systemd's own system will be used to query the
user for a passphrase).

Note that this is unrelated to supporting the "keyscript=" option in
systemd, but it is still an important part of providing a smooth
experience for users transitioning to systemd.

Regards,
David

---

Index: debian/askpass.c
===================================================================
--- debian/askpass.c	(revision 979)
+++ debian/askpass.c	(working copy)
@@ -140,7 +140,81 @@
 	goto again;
 }
 
+/*****************************************************************************
+ * systemd functions                                                         *
+ *****************************************************************************/
 
+#define SYSTEMD_ASKPASS "/bin/systemd-ask-password"
+static pid_t systemdpid;
+static size_t systemdused = 0;
+static size_t systemdsize = 0;
+static char *systemdbuf = NULL;
+
+static int
+systemd_prepare(const char *prompt)
+{
+	struct stat a, b;
+	int pipefds[2];
+
+	/* is systemd running? */
+	if (lstat("/sys/fs/cgroup", &a) < 0)
+		return -1;
+	if (lstat("/sys/fs/cgroup/systemd", &b) < 0)
+		return -1;
+	if (a.st_dev == b.st_dev)
+		return -1;
+
+	if (access(SYSTEMD_ASKPASS, X_OK))
+		return -1;
+
+	if (pipe(pipefds))
+		return -1;
+
+	systemdpid = fork();
+	if (systemdpid < 0) {
+		close(pipefds[0]);
+		close(pipefds[1]);
+		return -1;
+	}
+
+	if (systemdpid == 0) {
+		close(pipefds[0]);
+		if (dup2(pipefds[1], STDOUT_FILENO) < 0)
+			exit(EXIT_FAILURE);
+		execl(SYSTEMD_ASKPASS, SYSTEMD_ASKPASS,
+		      "--timeout=0", prompt, (char*)NULL);
+		exit(EXIT_FAILURE);
+	}
+
+	close(pipefds[1]);
+	return pipefds[0];
+}
+
+static bool
+systemd_read(int fd, char **buf, size_t *size)
+{
+	debug("In systemd_read\n");
+	if (fifo_common_read(fd, &systemdbuf, &systemdused, &systemdsize)) {
+		*buf = systemdbuf;
+		*size = systemdused;
+		/* systemd likes to include the terminating newline */
+		if (systemdused > 1 && systemdbuf[systemdused - 1] == '\n') {
+			systemdbuf[systemdused - 1] = '\0';
+			systemdused--;
+		}
+		return true;
+	}
+
+	return false;
+}
+
+static void
+systemd_finish(int fd)
+{
+	kill(systemdpid, SIGTERM);
+	fifo_common_finish(fd, &systemdbuf, &systemdused, &systemdsize);
+}
+
 /*****************************************************************************
  * splashy functions                                                         *
  *****************************************************************************/
@@ -366,6 +440,7 @@
 	int (*prepare)(const char *prompt);
 	bool (*read)(int fd, char **buf, size_t *size);
 	void (*finish)(int fd);
+	bool no_more;
 	bool active;
 	bool enabled;
 	int fd;
@@ -372,9 +447,10 @@
 };
 
 static struct method methods[] = {
-	{ "splashy", splashy_prepare, splashy_read, splashy_finish, false, true, -1 },
-	{ "fifo", fifo_prepare, fifo_read, fifo_finish, false, true, -1 },
-	{ "console", console_prepare, console_read, console_finish, false, true, -1 }
+	{ "systemd", systemd_prepare, systemd_read, systemd_finish, true, false, true, -1 },
+	{ "splashy", splashy_prepare, splashy_read, splashy_finish, false, false, true, -1 },
+	{ "fifo", fifo_prepare, fifo_read, fifo_finish, false, false, true, -1 },
+	{ "console", console_prepare, console_read, console_finish, false, false, true, -1 }
 };
 
 static bool
@@ -426,10 +502,15 @@
 			continue;
 		debug("Enabling method %s\n", methods[i].name);
 		methods[i].fd = methods[i].prepare(argv[1]);
-		if (methods[i].fd < 0)
+		if (methods[i].fd < 0) {
 			methods[i].active = false;
-		else
+			methods[i].enabled = false;
+		} else {
 			methods[i].active = true;
+			methods[i].enabled = true;
+			if (methods[i].no_more)
+				break;
+		}
 	}
 
 	while (!done) {