On 5/17/25 5:50 AM, Kuniyuki Iwashima wrote:
> Since commit 26abe14379f8 ("net: Modify sk_alloc to not reference
> count the netns of kernel sockets."), TCP kernel socket has caused
> many UAF.
>
> We have converted such sockets to hold netns refcnt, and we have
> the same pattern in cifs, mptcp, nvme, rds, smc, and sunrpc.
>
> __sock_create_kern(..., &sock);
> sk_net_refcnt_upgrade(sock->sk);
>
> Let's drop the conversion and use sock_create_kern() instead.
>
> The changes for cifs, mptcp, nvme, and smc are straightforward.
>
> For sunrpc, we call sock_create_net() for IPPROTO_TCP only and still
> call __sock_create_kern() for others.
>
> For rds, we cannot drop sk_net_refcnt_upgrade() for accept()ed
> sockets.
>
> Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
This LGTM, but is touching a few other subsystems, it would be great to
collect acks from the relevant maintainers: I'm adding a few CCs.
Direct link to the series:
https://lore.kernel.org/all/20250517035120.55560-1-kuniyu@xxxxxxxxxx/#t
> diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c
> index 37a2ba38f10e..c7b4f5a7cca1 100644
> --- a/fs/smb/client/connect.c
> +++ b/fs/smb/client/connect.c
> @@ -3348,21 +3348,14 @@ generic_ip_connect(struct TCP_Server_Info *server)
> socket = server->ssocket;
> } else {
> struct net *net = cifs_net_ns(server);
> - struct sock *sk;
>
> - rc = __sock_create_kern(net, sfamily, SOCK_STREAM,
> - IPPROTO_TCP, &server->ssocket);
> + rc = sock_create_kern(net, sfamily, SOCK_STREAM,
> + IPPROTO_TCP, &server->ssocket);
> if (rc < 0) {
> cifs_server_dbg(VFS, "Error %d creating socket\n", rc);
> return rc;
> }
>
> - sk = server->ssocket->sk;
> - __netns_tracker_free(net, &sk->ns_tracker, false);
> - sk->sk_net_refcnt = 1;
> - get_net_track(net, &sk->ns_tracker, GFP_KERNEL);
> - sock_inuse_add(net, 1);
AFAICS the above implicitly adds a missing net_passive_dec(net), which
in turns looks like a separate bugfix. What about adding a separate
patch introducing that line? Could be in the same series to simplify the
processing.
Thanks,
Paolo
