From 6644aabbd8973a9f8008cabfd054a36b69a3a3f5 Mon Sep 17 00:00:00 2001 From: Stanislav Fomichev Date: Thu, 4 Aug 2022 13:11:39 -0700 Subject: [PATCH] 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: b79c9fc9551b ("bpf: implement BPF_PROG_QUERY for BPF_LSM_CGROUP") Signed-off-by: Stanislav Fomichev Signed-off-by: Daniel Borkmann Acked-by: Hao Luo Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/bpf/20220804201140.1340684-1-sdf@google.com --- kernel/bpf/syscall.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 83c7136..7dc3f80 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -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; -- 2.7.4