Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Daniel Borkmann says:

====================
pull-request: bpf 2023-07-05

We've added 2 non-merge commits during the last 1 day(s) which contain
a total of 3 files changed, 16 insertions(+), 4 deletions(-).

The main changes are:

1) Fix BTF to warn but not returning an error for a NULL BTF to still be
   able to load modules under CONFIG_DEBUG_INFO_BTF, from SeongJae Park.

2) Fix xsk sockets to honor SO_BINDTODEVICE in bind(), from Ilya Maximets.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  xsk: Honor SO_BINDTODEVICE on bind
  bpf, btf: Warn but return no error for NULL btf from __register_btf_kfunc_id_set()
====================

Link: https://lore.kernel.org/r/20230705171716.6494-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

Documentation/networking/af_xdp.rst

@@ -433,6 +433,15 @@ start N bytes into the buffer leaving the first N bytes for the
 application to use. The final option is the flags field, but it will
 be dealt with in separate sections for each UMEM flag.
 
+SO_BINDTODEVICE setsockopt
+--------------------------
+
+This is a generic SOL_SOCKET option that can be used to tie AF_XDP
+socket to a particular network interface.  It is useful when a socket
+is created by a privileged process and passed to a non-privileged one.
+Once the option is set, kernel will refuse attempts to bind that socket
+to a different interface.  Updating the value requires CAP_NET_RAW.
+
 XDP_STATISTICS getsockopt
 -------------------------
 

kernel/bpf/btf.c

@@ -7891,10 +7891,8 @@ static int __register_btf_kfunc_id_set(enum btf_kfunc_hook hook,
 			pr_err("missing vmlinux BTF, cannot register kfuncs\n");
 			return -ENOENT;
 		}
-		if (kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) {
-			pr_err("missing module BTF, cannot register kfuncs\n");
-			return -ENOENT;
-		}
+		if (kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES))
+			pr_warn("missing module BTF, cannot register kfuncs\n");
 		return 0;
 	}
 	if (IS_ERR(btf))

net/xdp/xsk.c

@@ -886,6 +886,7 @@ static int xsk_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
 	struct sock *sk = sock->sk;
 	struct xdp_sock *xs = xdp_sk(sk);
 	struct net_device *dev;
+	int bound_dev_if;
 	u32 flags, qid;
 	int err = 0;
 
@@ -899,6 +900,10 @@ static int xsk_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
 		      XDP_USE_NEED_WAKEUP))
 		return -EINVAL;
 
+	bound_dev_if = READ_ONCE(sk->sk_bound_dev_if);
+	if (bound_dev_if && bound_dev_if != sxdp->sxdp_ifindex)
+		return -EINVAL;
+
 	rtnl_lock();
 	mutex_lock(&xs->mutex);
 	if (xs->state != XSK_READY) {