bpf: Return prog btf_id without capable check

Return prog's btf_id from bpf_prog_get_info_by_fd regardless of capable
check. This patch enables scenario, when freplace program, running
from user namespace, requires to query target prog's btf.

Signed-off-by: Mykyta Yatsenko <[email protected]>
Signed-off-by: Andrii Nakryiko <[email protected]>
Acked-by: Yonghong Song <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]

Author: mykyta5

kernel/bpf/syscall.c

@@ -4732,6 +4732,8 @@ static int bpf_prog_get_info_by_fd(struct file *file,
 	info.recursion_misses = stats.misses;
 
 	info.verified_insns = prog->aux->verified_insns;
+	if (prog->aux->btf)
+		info.btf_id = btf_obj_id(prog->aux->btf);
 
 	if (!bpf_capable()) {
 		info.jited_prog_len = 0;
@@ -4878,8 +4880,6 @@ static int bpf_prog_get_info_by_fd(struct file *file,
 		}
 	}
 
-	if (prog->aux->btf)
-		info.btf_id = btf_obj_id(prog->aux->btf);
 	info.attach_btf_id = prog->aux->attach_btf_id;
 	if (attach_btf)
 		info.attach_btf_obj_id = btf_obj_id(attach_btf);