bpf: Refactor btf_struct_access

Instead of having to pass multiple arguments that describe the register,
pass the bpf_reg_state into the btf_struct_access callback. Currently,
all call sites simply reuse the btf and btf_id of the reg they want to
check the access of. The only exception to this pattern is the callsite
in check_ptr_to_map_access, hence for that case create a dummy reg to
simulate PTR_TO_BTF_ID access.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20221114191547.1694267-8-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 7 insertions, 4 deletions

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index c0d73d71c539..875355ff3718 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -6017,15 +6017,18 @@ error:
 	return -EINVAL;
 }
 
-int btf_struct_access(struct bpf_verifier_log *log, const struct btf *btf,
-		      const struct btf_type *t, int off, int size,
-		      enum bpf_access_type atype __maybe_unused,
+int btf_struct_access(struct bpf_verifier_log *log,
+		      const struct bpf_reg_state *reg,
+		      int off, int size, enum bpf_access_type atype __maybe_unused,
 		      u32 *next_btf_id, enum bpf_type_flag *flag)
 {
+	const struct btf *btf = reg->btf;
 	enum bpf_type_flag tmp_flag = 0;
+	const struct btf_type *t;
+	u32 id = reg->btf_id;
 	int err;
-	u32 id;
 
+	t = btf_type_by_id(btf, id);
 	do {
 		err = btf_struct_walk(log, btf, t, off, size, &id, &tmp_flag);