bpf: offload: add infrastructure for loading programs for a specific netdev

The fact that we don't know which device the program is going
to be used on is quite limiting in current eBPF infrastructure.
We have to reverse or limit the changes which kernel makes to
the loaded bytecode if we want it to be offloaded to a networking
device.  We also have to invent new APIs for debugging and
troubleshooting support.

Make it possible to load programs for a specific netdev.  This
helps us to bring the debug information closer to the core
eBPF infrastructure (e.g. we will be able to reuse the verifer
log in device JIT).  It allows device JITs to perform translation
on the original bytecode.

__bpf_prog_get() when called to get a reference for an attachment
point will now refuse to give it if program has a device assigned.
Following patches will add a version of that function which passes
the expected netdev in. @type argument in __bpf_prog_get() is
renamed to attach_type to make it clearer that it's only set on
attachment.

All calls to ndo_bpf are protected by rtnl, only verifier callbacks
are not.  We need a wait queue to make sure netdev doesn't get
destroyed while verifier is still running and calling its driver.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 12 insertions, 3 deletions

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 04357ad5a812..51aabb32ad67 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3736,10 +3736,13 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
 static int ext_analyzer_insn_hook(struct bpf_verifier_env *env,
 				  int insn_idx, int prev_insn_idx)
 {
-	if (!env->analyzer_ops || !env->analyzer_ops->insn_hook)
-		return 0;
+	if (env->analyzer_ops && env->analyzer_ops->insn_hook)
+		return env->analyzer_ops->insn_hook(env, insn_idx,
+						    prev_insn_idx);
+	if (env->dev_ops && env->dev_ops->insn_hook)
+		return env->dev_ops->insn_hook(env, insn_idx, prev_insn_idx);
 
-	return env->analyzer_ops->insn_hook(env, insn_idx, prev_insn_idx);
+	return 0;
 }
 
 static int do_check(struct bpf_verifier_env *env)
@@ -4516,6 +4519,12 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr)
 	if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
 		env->strict_alignment = true;
 
+	if (env->prog->aux->offload) {
+		ret = bpf_prog_offload_verifier_prep(env);
+		if (ret)
+			goto err_unlock;
+	}
+
 	ret = replace_map_fd_with_map_ptr(env);
 	if (ret < 0)
 		goto skip_full_check;