[PATCH v2 09/20] insert: prevent writes outside Maildir hierarchy

[Peter Wang]

Don't accept a --folder name that contains a ".." component,
in order to prevent writing outside of the Maildir hierarchy.
---
 notmuch-insert.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/notmuch-insert.c b/notmuch-insert.c
index a50eacc..022f7cd 100644
--- a/notmuch-insert.c
+++ b/notmuch-insert.c
@@ -38,6 +38,23 @@ safe_gethostname (char *hostname, size_t len)
     return (strchr (hostname, '/') == NULL);
 }
 
+/* Check the specified folder name does not contain a directory
+ * component ".." to prevent writes outside of the Maildir hierarchy. */
+static notmuch_bool_t
+check_folder_name (const char *folder)
+{
+    const char *p = folder;
+
+    for (;;) {
+	if ((p[0] == '.') && (p[1] == '.') && (p[2] == '\0' || p[2] == '/'))
+	    return FALSE;
+	p = strchr (p, '/');
+	if (!p)
+	    return TRUE;
+	p++;
+    }
+}
+
 /* Open a unique file in the Maildir 'tmp' directory.
  * Returns the file descriptor on success, or -1 on failure.
  * On success, file paths into the 'tmp' and 'new' directories are returned
@@ -255,6 +272,10 @@ notmuch_insert_command (void *ctx, int argc, char *argv[])
     db_path = notmuch_config_get_database_path (config);
 
     if (folder != NULL) {
+	if (! check_folder_name (folder)) {
+	    fprintf (stderr, "Error: bad folder name: %s\n", folder);
+	    return 1;
+	}
 	maildir = talloc_asprintf (ctx, "%s/%s", db_path, folder);
     } else {
 	maildir = talloc_asprintf (ctx, "%s", db_path);
-- 
1.7.12.1