From patchwork Sun Mar 28 11:26:26 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Jiri Olsa X-Patchwork-Id: 410756 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-14.0 required=3.0 tests=BAYES_00, INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6E116C433E4 for ; Sun, 28 Mar 2021 11:27:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4F1FC61972 for ; Sun, 28 Mar 2021 11:27:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231260AbhC1L1I convert rfc822-to-8bit (ORCPT ); Sun, 28 Mar 2021 07:27:08 -0400 Received: from us-smtp-delivery-44.mimecast.com ([205.139.111.44]:40833 "EHLO us-smtp-delivery-44.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230526AbhC1L0s (ORCPT ); Sun, 28 Mar 2021 07:26:48 -0400 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-146-JzK_RUyqOJ2QtYWoe_YUBQ-1; Sun, 28 Mar 2021 07:26:41 -0400 X-MC-Unique: JzK_RUyqOJ2QtYWoe_YUBQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id F41D4107ACCA; Sun, 28 Mar 2021 11:26:39 +0000 (UTC) Received: from krava.redhat.com (unknown [10.40.192.12]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5D7BD19C66; Sun, 28 Mar 2021 11:26:37 +0000 (UTC) From: Jiri Olsa To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= Subject: [RFC PATCH bpf-next 1/4] bpf: Allow trampoline re-attach Date: Sun, 28 Mar 2021 13:26:26 +0200 Message-Id: <20210328112629.339266-2-jolsa@kernel.org> In-Reply-To: <20210328112629.339266-1-jolsa@kernel.org> References: <20210328112629.339266-1-jolsa@kernel.org> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jolsa@kernel.org X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Currently we don't allow re-attaching of trampolines. Once it's detached, it can't be re-attach even when the program is still loaded. Adding the possibility to re-attach the loaded tracing kernel program. Signed-off-by: Jiri Olsa Acked-by: Song Liu Acked-by: Toke Høiland-Jørgensen --- kernel/bpf/syscall.c | 25 +++++++++++++++++++------ kernel/bpf/trampoline.c | 2 +- 2 files changed, 20 insertions(+), 7 deletions(-) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 9603de81811a..e14926b2e95a 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2645,14 +2645,27 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog, * target_btf_id using the link_create API. * * - if tgt_prog == NULL when this function was called using the old - * raw_tracepoint_open API, and we need a target from prog->aux - * - * The combination of no saved target in prog->aux, and no target - * specified on load is illegal, and we reject that here. + * raw_tracepoint_open API, and we need a target from prog->aux + * + * The combination of no saved target in prog->aux, and no target + * specified on is legal only for tracing programs re-attach, rest + * is illegal, and we reject that here. */ if (!prog->aux->dst_trampoline && !tgt_prog) { - err = -ENOENT; - goto out_unlock; + /* + * Allow re-attach for tracing programs, if it's currently + * linked, bpf_trampoline_link_prog will fail. + */ + if (prog->type != BPF_PROG_TYPE_TRACING) { + err = -ENOENT; + goto out_unlock; + } + if (!prog->aux->attach_btf) { + err = -EINVAL; + goto out_unlock; + } + btf_id = prog->aux->attach_btf_id; + key = bpf_trampoline_compute_key(NULL, prog->aux->attach_btf, btf_id); } if (!prog->aux->dst_trampoline || diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 4aa8b52adf25..0d937c63fc22 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -467,7 +467,7 @@ int bpf_trampoline_unlink_prog(struct bpf_prog *prog, struct bpf_trampoline *tr) tr->extension_prog = NULL; goto out; } - hlist_del(&prog->aux->tramp_hlist); + hlist_del_init(&prog->aux->tramp_hlist); tr->progs_cnt[kind]--; err = bpf_trampoline_update(tr); out: