From patchwork Tue Sep 29 12:45:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= X-Patchwork-Id: 289394 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=-10.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED 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 3F013C47423 for ; Tue, 29 Sep 2020 12:46:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D6EAB208B8 for ; Tue, 29 Sep 2020 12:46:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="BzC7CmSj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728640AbgI2MqY (ORCPT ); Tue, 29 Sep 2020 08:46:24 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:42667 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387559AbgI2MqG (ORCPT ); Tue, 29 Sep 2020 08:46:06 -0400 Dkim-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1601383564; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=nneNQXug1AmXlFY8BQ86fIMPd4vSghG2g/V1b4Wro3s=; b=BzC7CmSjGYdcJLJFa/QoFHm2hp5d+1gE3z50BiXb42ms5NFecYI1W6uR6VJ9M928tj/Gio fOa99W49Fn9KZSO8TWq1uMH2CPIKM0vzer87dngdu74snPZUo9WYCAGthXLZ3rjEQZLc/M Wzs1IjFpGdVhvWkFWnWgCTtC/q+dF8Y= Received: from mail-ot1-f70.google.com (mail-ot1-f70.google.com [209.85.210.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-578-86S_GoQYMI6OWjSjzreQ8Q-1; Tue, 29 Sep 2020 08:46:02 -0400 X-MC-Unique: 86S_GoQYMI6OWjSjzreQ8Q-1 Received: by mail-ot1-f70.google.com with SMTP id c23so3128563otn.12 for ; Tue, 29 Sep 2020 05:46:02 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:date:message-id:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=nneNQXug1AmXlFY8BQ86fIMPd4vSghG2g/V1b4Wro3s=; b=M47JebWS7eGgOwmLhhEp2r7w/WlTimY6zcrJBFmghpCUX+Hu5R9Ro+2CxfYulOSCLw O3YWhuj8bGxr9rE0zWhGldTh/NOsPu3hfJ+zcLQBjZvI5y/2r8BDge05FoUmByIQu/2o JmCVAzNSnbNm8IKLQXZTZvADvVq9sWgfxeahSwZiPH7PgRe2cevCEayXeRyas0Myo4ry L8RkGFVbK3GPC6Gv5FrrME5EWPyTqB5NHgxmjl4ffllPs09asufEJM/w3l9Rh5G8UuaX HhcKRXomWnrpVVu/dtt6IIScHMh9wWhLV+asAJbTA110Saq1Nl7oeOfs+U2p47U6A7qu XyyQ== X-Gm-Message-State: AOAM530zl3KqQ8da7cUJTeZ8NfuPVzxwj8TYQwkZjvlauLT6jsQIYjBu 0KQgzhDskNNc+OCkJj7i1A01x9Mwyvl0kuMdzc2olgXDZ4ZDbChOptZw6YpEECC/Q8adBFxSrXT g1cK+7VeS4jskXipp X-Received: by 2002:a05:6830:2096:: with SMTP id y22mr2664446otq.158.1601383557047; Tue, 29 Sep 2020 05:45:57 -0700 (PDT) X-Google-Smtp-Source: ABdhPJztMDEwLpRQfY2JKWPLy52gemqcQHpYHTXQGIijJbdpay5BjjGBDHOS6X6VPep3e844G60xJw== X-Received: by 2002:a05:6830:2096:: with SMTP id y22mr2664419otq.158.1601383556699; Tue, 29 Sep 2020 05:45:56 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk ([2a0c:4d80:42:443::2]) by smtp.gmail.com with ESMTPSA id m14sm2860523oov.37.2020.09.29.05.45.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Sep 2020 05:45:55 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id D5E67183C5F; Tue, 29 Sep 2020 14:45:52 +0200 (CEST) Subject: [PATCH bpf-next v10 3/7] bpf: Fix context type resolving for extension programs From: =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= To: Alexei Starovoitov Cc: Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , John Fastabend , Jiri Olsa , Eelco Chaudron , KP Singh , netdev@vger.kernel.org, bpf@vger.kernel.org Date: Tue, 29 Sep 2020 14:45:52 +0200 Message-ID: <160138355278.48470.17057040257274725638.stgit@toke.dk> In-Reply-To: <160138354947.48470.11523413403103182788.stgit@toke.dk> References: <160138354947.48470.11523413403103182788.stgit@toke.dk> User-Agent: StGit/0.23 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Toke Høiland-Jørgensen Eelco reported we can't properly access arguments if the tracing program is attached to extension program. Having following program: SEC("classifier/test_pkt_md_access") int test_pkt_md_access(struct __sk_buff *skb) with its extension: SEC("freplace/test_pkt_md_access") int test_pkt_md_access_new(struct __sk_buff *skb) and tracing that extension with: SEC("fentry/test_pkt_md_access_new") int BPF_PROG(fentry, struct sk_buff *skb) It's not possible to access skb argument in the fentry program, with following error from verifier: ; int BPF_PROG(fentry, struct sk_buff *skb) 0: (79) r1 = *(u64 *)(r1 +0) invalid bpf_context access off=0 size=8 The problem is that btf_ctx_access gets the context type for the traced program, which is in this case the extension. But when we trace extension program, we want to get the context type of the program that the extension is attached to, so we can access the argument properly in the trace program. This version of the patch is tweaked slightly from Jiri's original one, since the refactoring in the previous patches means we have to get the target prog type from the new variable in prog->aux instead of directly from the target prog. Reported-by: Eelco Chaudron Suggested-by: Jiri Olsa Acked-by: Andrii Nakryiko Signed-off-by: Toke Høiland-Jørgensen --- kernel/bpf/btf.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 05816471bac6..4d0ee7839fdb 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -4582,7 +4582,14 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, info->reg_type = PTR_TO_BTF_ID; if (tgt_prog) { - ret = btf_translate_to_vmlinux(log, btf, t, tgt_prog->type, arg); + enum bpf_prog_type tgt_type; + + if (tgt_prog->type == BPF_PROG_TYPE_EXT) + tgt_type = tgt_prog->aux->saved_dst_prog_type; + else + tgt_type = tgt_prog->type; + + ret = btf_translate_to_vmlinux(log, btf, t, tgt_type, arg); if (ret > 0) { info->btf_id = ret; return true;