Harden create_temp_filename() (version 2)

By hardening the create_temp_filename() function to check if the generated
filename exists and to create the temp file with only S_IRUSR|S_IWUSR bit
files set before calling the script, it should become even more difficult to
exploit such a scenario.

After a discussion on the mailing list, Fabian Knittel provided an enhanced
version of the inital patch which is added to this patch.

This patch also renames create_temp_filename() to create_temp_file(), as this
patch also creates the temporary file.  The function returns the filename of the
created file, or NULL on error.

Signed-off-by: David Sommerseth <dazo@users.sourceforge.net>
Signed-off-by: Fabian Knittel <fabian.knittel@avona.com>
Acked-by: Gert Doering <gert@greenie.muc.de>

1 files changed, 2 insertions, 2 deletions

diff --git a/misc.h b/misc.h
index bf51e89..e3ce19e 100644
--- a/misc.h
+++ b/misc.h
@@ -218,8 +218,8 @@ long int get_random(void);
 /* return true if filename can be opened for read */
 bool test_file (const char *filename);
 
-/* create a temporary filename in directory */
-const char *create_temp_filename (const char *directory, const char *prefix, struct gc_arena *gc);
+/* create a temporary file in directory, returns the filename of the created file */
+const char *create_temp_file (const char *directory, const char *prefix, struct gc_arena *gc);
 
 /* put a directory and filename together */
 const char *gen_path (const char *directory, const char *filename, struct gc_arena *gc);