bpf: Support consuming XDP HW metadata from fext programs

Instead of rejecting the attaching of PROG_TYPE_EXT programs to XDP
programs that consume HW metadata, implement support for propagating the
offload information. The extension program doesn't need to set a flag or
ifindex, these will just be propagated from the target by the verifier.
We need to create a separate offload object for the extension program,
though, since it can be reattached to a different program later (which
means we can't just inherit the offload information from the target).

An additional check is added on attach that the new target is compatible
with the offload information in the extension prog.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20230119221536.3349901-9-sdf@google.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index bb26c2e18092..ad4bb36d4c10 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2484,6 +2484,7 @@ int bpf_dev_bound_kfunc_check(struct bpf_verifier_log *log,
 			      struct bpf_prog_aux *prog_aux);
 void *bpf_dev_bound_resolve_kfunc(struct bpf_prog *prog, u32 func_id);
 int bpf_prog_dev_bound_init(struct bpf_prog *prog, union bpf_attr *attr);
+int bpf_prog_dev_bound_inherit(struct bpf_prog *new_prog, struct bpf_prog *old_prog);
 void bpf_dev_bound_netdev_unregister(struct net_device *dev);
 
 static inline bool bpf_prog_is_dev_bound(const struct bpf_prog_aux *aux)
@@ -2496,6 +2497,8 @@ static inline bool bpf_prog_is_offloaded(const struct bpf_prog_aux *aux)
 	return aux->offload_requested;
 }
 
+bool bpf_prog_dev_bound_match(const struct bpf_prog *lhs, const struct bpf_prog *rhs);
+
 static inline bool bpf_map_is_offloaded(struct bpf_map *map)
 {
 	return unlikely(map->ops == &bpf_map_offload_ops);
@@ -2535,6 +2538,12 @@ static inline int bpf_prog_dev_bound_init(struct bpf_prog *prog,
 	return -EOPNOTSUPP;
 }
 
+static inline int bpf_prog_dev_bound_inherit(struct bpf_prog *new_prog,
+					     struct bpf_prog *old_prog)
+{
+	return -EOPNOTSUPP;
+}
+
 static inline void bpf_dev_bound_netdev_unregister(struct net_device *dev)
 {
 }
@@ -2549,6 +2558,11 @@ static inline bool bpf_prog_is_offloaded(struct bpf_prog_aux *aux)
 	return false;
 }
 
+static inline bool bpf_prog_dev_bound_match(const struct bpf_prog *lhs, const struct bpf_prog *rhs)
+{
+	return false;
+}
+
 static inline bool bpf_map_is_offloaded(struct bpf_map *map)
 {
 	return false;