[PATCH] Listening socket tweaks

[Kristian Høgsberg]

On Mon, Feb 7, 2011 at 4:39 AM, Marty Jack <martyj19 at comcast.net> wrote:
> With this patch, crashed compositors won't prevent a new one from starting, and unprivileged clients can connect.

Hi Marty,

The compositor is supposed to run as the user, not root, and the
restrictive permissions on the unix socket is how we authorize access
to the compositor.  The socket will be placed in $XDG_RUNTIME_DIR, see

  http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html

If there's already a socket in there, we can't just unlink it, it
could belong to a running compositor.

Kristian

> diff --git a/wayland/wayland-server.c b/wayland/wayland-server.c
> index dece0d1..6b5f503 100644
> --- a/wayland/wayland-server.c
> +++ b/wayland/wayland-server.c
> @@ -33,6 +33,7 @@
>  #include <dlfcn.h>
>  #include <assert.h>
>  #include <sys/time.h>
> +#include <sys/stat.h>
>  #include <ffi.h>
>
>  #include "wayland-server.h"
> @@ -675,10 +676,20 @@ wl_display_add_socket(struct wl_display *display, const char *name)
>                             "%s/%s", runtime_dir, name) + 1;
>        fprintf(stderr, "using socket %s\n", s->addr.sun_path);
>
> +       /* If the entry exists and is a socket, unlink it to prevent the bind from failing.
> +        * It is probably a socket left over from a previous compositor that crashed. */
> +       struct stat stat_buf;
> +       if ((stat(s->addr.sun_path, &stat_buf) == 0)
> +       && (S_ISSOCK(stat_buf.st_mode)))
> +               unlink(s->addr.sun_path);
> +
>        size = offsetof (struct sockaddr_un, sun_path) + name_size;
>        if (bind(s->fd, (struct sockaddr *) &s->addr, size) < 0)
>                return -1;
>
> +       /* Set protections so unprivileged clients can connect. */
> +       chmod(s->addr.sun_path, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
> +
>        if (listen(s->fd, 1) < 0)
>                return -1;
>
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