dma - Fix security hole (#46)

Affecting DragonFly 4.6 and earlier, Matt Dillon fixed this in base after
finding out from BSDNow Episode 152. Comments following were from his commit
which explains better than I. Just taking his change and putting it here as well.

* dma makes an age-old mistake of not properly checking whether a file
  owned by a user is a symlink or not, a bug which the original mail.local
  also had.

* Add O_NOFOLLOW to disallow symlinks.

Thanks-to: BSDNow Episode 152, made me dive dma to check when they talked
           about the mail.local bug.

diff --git a/dma-mbox-create.c b/dma-mbox-create.c
index 532a7afbe0b53b43bf23515b4de8deec66ed367e..45a4792a3f6f498c7227d34b7defeea7bb1a52ac 100644 (file)
--- a/dma-mbox-create.c
+++ b/dma-mbox-create.c
@@ -142,7 +142,7 @@ main(int argc, char **argv)
                logfail(EX_CANTCREAT, "cannot build mbox path for `%s/%s'", _PATH_MAILDIR, user);
        }
 
-       f = open(fn, O_RDONLY|O_CREAT, 0600);
+       f = open(fn, O_RDONLY|O_CREAT|O_NOFOLLOW, 0600);
        if (f < 0)
                logfail(EX_NOINPUT, "cannt open mbox `%s'", fn);