[PATCH bpf 1/2] bpf, tcx: reject offloaded programs on attach

[Jiayuan Chen <jiayuan.chen@linux.dev>]

An offloaded prog's bpf_func is replaced by bpf_prog_warn_on_exec(),
since it's supposed to run on the NIC, not the host. But tcx doesn't
check this and happily attaches it to the software path, so the first
packet hits the WARN.

XDP already guards this in dev_xdp_attach(); tcx just never got the
same check. Add it to both tcx_prog_attach() and tcx_link_attach().

Use bpf_prog_is_offloaded() instead of bpf_prog_is_dev_bound() so that
dev-bound-only programs (still JITed for host) keep working.

Fixes: e420bed025071 ("bpf: Add fd-based tcx multi-prog infra with link support")
Reported-by: Yinhao Hu <dddddd@hust.edu.cn>
Reported-by: Kaiyan Mei <M202472210@hust.edu.cn>
Reported-by: Dongliang Mu <dzm91@hust.edu.cn>
Closes: https://lore.kernel.org/bpf/64d8e2b5-a214-4f3c-b9e8-bcedbcb2c602@hust.edu.cn/
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
---
 kernel/bpf/tcx.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/kernel/bpf/tcx.c b/kernel/bpf/tcx.c
index 02db0113b8e7c..86f4636d5a677 100644
--- a/kernel/bpf/tcx.c
+++ b/kernel/bpf/tcx.c
@@ -16,6 +16,9 @@ int tcx_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
 	struct net_device *dev;
 	int ret;
 
+	if (bpf_prog_is_offloaded(prog->aux))
+		return -EINVAL;
+
 	rtnl_lock();
 	dev = __dev_get_by_index(net, attr->target_ifindex);
 	if (!dev) {
@@ -315,6 +318,9 @@ int tcx_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
 	struct tcx_link *tcx;
 	int ret;
 
+	if (bpf_prog_is_offloaded(prog->aux))
+		return -EINVAL;
+
 	rtnl_lock();
 	dev = __dev_get_by_index(net, attr->link_create.target_ifindex);
 	if (!dev) {
-- 
2.43.0