bpf: XDP metadata RX kfuncs

Define a new kfunc set (xdp_metadata_kfunc_ids) which implements all possible
XDP metatada kfuncs. Not all devices have to implement them. If kfunc is not
supported by the target device, the default implementation is called instead.
The verifier, at load time, replaces a call to the generic kfunc with a call
to the per-device one. Per-device kfunc pointers are stored in separate
struct xdp_metadata_ops.

Cc: John Fastabend <john.fastabend@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Anatoly Burakov <anatoly.burakov@intel.com>
Cc: Alexander Lobakin <alexandr.lobakin@intel.com>
Cc: Magnus Karlsson <magnus.karlsson@gmail.com>
Cc: Maryam Tahhan <mtahhan@redhat.com>
Cc: xdp-hints@xdp-project.net
Cc: netdev@vger.kernel.org
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20230119221536.3349901-8-sdf@google.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

1 files changed, 24 insertions, 1 deletions

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index bba68eefb4b2..9009395206f8 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2333,6 +2333,12 @@ static int add_kfunc_call(struct bpf_verifier_env *env, u32 func_id, s16 offset)
 		return -EINVAL;
 	}
 
+	if (bpf_dev_bound_kfunc_id(func_id)) {
+		err = bpf_dev_bound_kfunc_check(&env->log, prog_aux);
+		if (err)
+			return err;
+	}
+
 	desc = &tab->descs[tab->nr_descs++];
 	desc->func_id = func_id;
 	desc->imm = call_imm;
@@ -15772,12 +15778,25 @@ static int fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
 			    struct bpf_insn *insn_buf, int insn_idx, int *cnt)
 {
 	const struct bpf_kfunc_desc *desc;
+	void *xdp_kfunc;
 
 	if (!insn->imm) {
 		verbose(env, "invalid kernel function call not eliminated in verifier pass\n");
 		return -EINVAL;
 	}
 
+	*cnt = 0;
+
+	if (bpf_dev_bound_kfunc_id(insn->imm)) {
+		xdp_kfunc = bpf_dev_bound_resolve_kfunc(env->prog, insn->imm);
+		if (xdp_kfunc) {
+			insn->imm = BPF_CALL_IMM(xdp_kfunc);
+			return 0;
+		}
+
+		/* fallback to default kfunc when not supported by netdev */
+	}
+
 	/* insn->imm has the btf func_id. Replace it with
 	 * an address (relative to __bpf_call_base).
 	 */
@@ -15788,7 +15807,6 @@ static int fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
 		return -EFAULT;
 	}
 
-	*cnt = 0;
 	insn->imm = desc->imm;
 	if (insn->off)
 		return 0;
@@ -16795,6 +16813,11 @@ int bpf_check_attach_target(struct bpf_verifier_log *log,
 	if (tgt_prog) {
 		struct bpf_prog_aux *aux = tgt_prog->aux;
 
+		if (bpf_prog_is_dev_bound(tgt_prog->aux)) {
+			bpf_log(log, "Replacing device-bound programs not supported\n");
+			return -EINVAL;
+		}
+
 		for (i = 0; i < aux->func_info_cnt; i++)
 			if (aux->func_info[i].type_id == btf_id) {
 				subprog = i;