Support direct fixed-size (and for now, read-only) memory access when
kfunc's return type is a pointer to non-struct type. Calculate type size
and let BPF program access that many bytes directly. This is crucial for
numbers iterator.
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
kernel/bpf/verifier.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 641a36204493..0ff9dd9170ef 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -10241,6 +10241,14 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
return -EFAULT;
}
} else if (!__btf_type_is_struct(ptr_type)) {
+ if (!meta.r0_size) {
+ __u32 sz;
+
+ if (!IS_ERR(btf_resolve_size(desc_btf, ptr_type, &sz))) {
+ meta.r0_size = sz;
+ meta.r0_rdonly = true;
+ }
+ }
if (!meta.r0_size) {
ptr_type_name = btf_name_by_offset(desc_btf,
ptr_type->name_off);
--
2.30.2
