[PATCH] mount.cifs: Use systemd's mechanism for getting password, if present

[Ankit Jain <jankit-IBi9RG/b67k@public.gmane.org>]

If the mount requests are "from" cifstab, then just asking for
"Password:" would be unclear, this asks it as:
  "Password for user@.. :"

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---
mount.cifs: Use systemd's mechanism for getting password, if present.
    
If systemd is running, then use /bin/systemd-ask-password to get
the password instead of get_pass(..) .

Reference: bug: https://bugzilla.novell.com/show_bug.cgi?id=767894

diff --git a/mount.cifs.c b/mount.cifs.c
index 6f3f382..d721de6 100644
--- a/mount.cifs.c
+++ b/mount.cifs.c
@@ -1687,6 +1687,58 @@ drop_child_privs(void)
 	return 0;
 }
 
+/*
+ * If systemd is present, then try to get password via
+ * /bin/systemd-ask-password, else just use getpass(..)
+ */
+static char*
+get_password(const char *prompt, char *input, int capacity)
+{
+	int is_systemd_running;
+	struct stat a, b;
+
+	/* We simply test whether the systemd cgroup hierarchy is
+	 * mounted */
+	is_systemd_running = (lstat("/sys/fs/cgroup", &a) == 0)
+		&& (lstat("/sys/fs/cgroup/systemd", &b) == 0)
+		&& (a.st_dev != b.st_dev);
+
+	if (is_systemd_running) {
+		/* systemd */
+		char *cmd;
+		FILE *fp = NULL;
+
+		if (asprintf(&cmd, "/bin/systemd-ask-password \"%s\"", prompt) >= 0) {
+			fp = popen (cmd, "re");
+			free (cmd);
+		}
+
+		if (!fp)
+			return NULL;
+
+		if (fgets(input, capacity, fp)) {
+			int len = strlen(input);
+			if (input[len - 1] == '\n')
+				input[len - 1] = '\0';
+		}
+
+		fclose(fp);
+	} else {
+		/* getpass is obsolete, but there's apparently nothing that replaces it */
+		char *tmp_pass = getpass(prompt);
+		if (!tmp_pass)
+			return NULL;
+
+		strncpy(input, tmp_pass, capacity - 1);
+		input[capacity - 1] = '\0';
+
+		/* zero-out the static buffer */
+		memset(tmp_pass, 0, strlen(tmp_pass));
+	}
+
+	return input;
+}
+
 static int
 assemble_mountinfo(struct parsed_mount_info *parsed_info,
 		   const char *thisprogram, const char *mountpoint,
@@ -1768,14 +1820,20 @@ assemble_mountinfo(struct parsed_mount_info *parsed_info,
 	}
 
 	if (!parsed_info->got_password) {
-		/* getpass is obsolete, but there's apparently nothing that replaces it */
-		char *tmp_pass = getpass("Password: ");
-		if (!tmp_pass) {
+		char tmp_pass[MOUNT_PASSWD_SIZE + 1];
+		char *prompt = NULL;
+
+		if(asprintf(&prompt, "Password for %s@%s: ", parsed_info->username, orig_dev) < 0)
+			prompt = NULL;
+
+		if (get_password(prompt ? prompt : "Password: ", tmp_pass, MOUNT_PASSWD_SIZE + 1)) {
+			rc = set_password(parsed_info, tmp_pass);
+		} else {
 			fprintf(stderr, "Error reading password, exiting\n");
 			rc = EX_SYSERR;
-			goto assemble_exit;
 		}
-		rc = set_password(parsed_info, tmp_pass);
+
+		free(prompt);
 		if (rc)
 			goto assemble_exit;
 	}

-- 
Ankit Jain
SUSE Labs