Commit 6644aabb authored by Stanislav Fomichev's avatar Stanislav Fomichev Committed by Daniel Borkmann
Browse files

bpf: Use proper target btf when exporting attach_btf_obj_id 



When attaching to program, the program itself might not be attached
to anything (and, hence, might not have attach_btf), so we can't
unconditionally use 'prog->aux->dst_prog->aux->attach_btf'.

Instead, use bpf_prog_get_target_btf to pick proper target BTF:

  * when attached to dst_prog, use dst_prog->aux->btf
  * when attached to kernel btf, use prog->aux->attach_btf

Fixes: b79c9fc9 ("bpf: implement BPF_PROG_QUERY for BPF_LSM_CGROUP")
Signed-off-by: default avatarStanislav Fomichev <sdf@google.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarHao Luo <haoluo@google.com>
Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20220804201140.1340684-1-sdf@google.com
parent f1d41f77

kernel/bpf/syscall.c

+3 −4
Original line number Diff line number Diff line
@@ -3886,6 +3886,7 @@ static int bpf_prog_get_info_by_fd(struct file *file, 
				   union bpf_attr __user *uattr)

{

	struct bpf_prog_info __user *uinfo = u64_to_user_ptr(attr->info.info);

	struct btf *attach_btf = bpf_prog_get_target_btf(prog);

	struct bpf_prog_info info;

	u32 info_len = attr->info.info_len;

	struct bpf_prog_kstats stats;
@@ -4088,10 +4089,8 @@ 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 (prog->aux->attach_btf)

		info.attach_btf_obj_id = btf_obj_id(prog->aux->attach_btf);

	else if (prog->aux->dst_prog)

		info.attach_btf_obj_id = btf_obj_id(prog->aux->dst_prog->aux->attach_btf);

	if (attach_btf)

		info.attach_btf_obj_id = btf_obj_id(attach_btf);



	ulen = info.nr_func_info;

	info.nr_func_info = prog->aux->func_info_cnt;