Re: [PATCH v8 1/4] Landlock: Add abstract unix socket connect restriction

From: Jann Horn
Date: Tue Aug 06 2024 - 15:38:19 EST


On Fri, Aug 2, 2024 at 6:03 AM Tahera Fahimi <fahimitahera@xxxxxxxxx> wrote:
> This patch introduces a new "scoped" attribute to the landlock_ruleset_attr
> that can specify "LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET" to scope
> abstract Unix sockets from connecting to a process outside of
> the same landlock domain. It implements two hooks, unix_stream_connect
> and unix_may_send to enforce this restriction.
[...]
> +static bool check_unix_address_format(struct sock *const sock)
> +{
> + struct unix_address *addr = unix_sk(sock)->addr;
> +
> + if (!addr)
> + return true;
> +
> + if (addr->len > sizeof(AF_UNIX)) {
> + /* handling unspec sockets */
> + if (!addr->name[0].sun_path)
> + return true;

addr->name[0] is a "struct sockaddr_un", whose member "sun_path" is an
array member, not a pointer. If "addr" is a valid pointer,
"addr->name[0].sun_path" can't be NULL.


> + if (addr->name[0].sun_path[0] == '\0')
> + if (!sock_is_scoped(sock))
> + return false;
> + }
> +
> + return true;
> +}