Re: [PATCH v5.15-v5.4] net, sunrpc: Remap EPERM in case of connection failure in xs_tcp_setup_socket

[Greg KH <greg@kroah.com>]

On Mon, Sep 09, 2024 at 06:15:48PM +0200, hsimeliere.opensource@witekio.com wrote:
> From: Daniel Borkmann <daniel@iogearbox.net>
> 
> commit 626dfed5fa3bfb41e0dffd796032b555b69f9cde upstream.
> 
> When using a BPF program on kernel_connect(), the call can return -EPERM. This
> causes xs_tcp_setup_socket() to loop forever, filling up the syslog and causing
> the kernel to potentially freeze up.
> 
> Neil suggested:
> 
>   This will propagate -EPERM up into other layers which might not be ready
>   to handle it. It might be safer to map EPERM to an error we would be more
>   likely to expect from the network system - such as ECONNREFUSED or ENETDOWN.
> 
> ECONNREFUSED as error seems reasonable. For programs setting a different error
> can be out of reach (see handling in 4fbac77d2d09) in particular on kernels
> which do not have f10d05966196 ("bpf: Make BPF_PROG_RUN_ARRAY return -err
> instead of allow boolean"), thus given that it is better to simply remap for
> consistent behavior. UDP does handle EPERM in xs_udp_send_request().
> 
> Fixes: d74bad4e74ee ("bpf: Hooks for sys_connect")
> Fixes: 4fbac77d2d09 ("bpf: Hooks for sys_bind")
> Co-developed-by: Lex Siegel <usiegl00@gmail.com>
> Signed-off-by: Lex Siegel <usiegl00@gmail.com>
> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
> Cc: Neil Brown <neilb@suse.de>
> Cc: Trond Myklebust <trondmy@kernel.org>
> Cc: Anna Schumaker <anna@kernel.org>
> Link: https://github.com/cilium/cilium/issues/33395
> Link: https://lore.kernel.org/bpf/171374175513.12877.8993642908082014881@noble.neil.brown.name
> Link: https://patch.msgid.link/9069ec1d59e4b2129fc23433349fd5580ad43921.1720075070.git.daniel@iogearbox.net
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> Signed-off-by: Hugo SIMELIERE <hsimeliere.opensource@witekio.com>
> ---
>  net/sunrpc/xprtsock.c | 7 +++++++
>  1 file changed, 7 insertions(+)

Now queued up, thanks.

greg k-h