From patchwork Thu Sep 17 20:20:07 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: 260697 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=-12.8 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 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 47C9CC43463 for ; Thu, 17 Sep 2020 20:20:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 15F88206B7 for ; Thu, 17 Sep 2020 20:20:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="cK8wGwIw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726716AbgIQUUe (ORCPT ); Thu, 17 Sep 2020 16:20:34 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:36774 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726551AbgIQUUO (ORCPT ); Thu, 17 Sep 2020 16:20:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600374012; 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=yIGbpCZmz89BH4RaSE1d8nNgeBGwQPZU+jdCtpvbXO4=; b=cK8wGwIwO3/1v2FhspdUGfLIKGkvbKrBp+z2d9bUdDXfgX5Tfk6i3Rlpqznf5a/RDWPkXj ojR00d/2uG/0emU+MxZ8Gmb49guvmFgJ1JZsRQsRQQBUYp0yY4Vtv6zyT4CAcCxzDST1Zm 83ItDSjaBf/EaiWv5JFrwHMjb6dG8Xw= Received: from mail-ej1-f71.google.com (mail-ej1-f71.google.com [209.85.218.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-166-_khjAWMHNWqR2D9W5afuMQ-1; Thu, 17 Sep 2020 16:20:11 -0400 X-MC-Unique: _khjAWMHNWqR2D9W5afuMQ-1 Received: by mail-ej1-f71.google.com with SMTP id hh10so1328440ejb.13 for ; Thu, 17 Sep 2020 13:20:10 -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=yIGbpCZmz89BH4RaSE1d8nNgeBGwQPZU+jdCtpvbXO4=; b=pUQ2By2ikBjt/Lb1WZyIJEvyvKzGZCR47DcoAovoJG+Zoafec7MtQz6sjQGCkbXkFv rR38mjOI6SxxZKJImsuGz1EnrXlvsYj5qxaGKnMRwPlnXirT3HtA3VNdFFTEz2unMSXi 5JL1t95rg2iHwQHZRBLaTGiUkOl2ZYA9n4wBqvSKWJtUPzDtCOoWoHcsHQ3eEzfLOLh6 yIWPffG8jJ2PLfQwThyohFftPq9YO1RVGygLxeQyS9mR1DBw1bVrvGehz0Pkd9uMW3ML 3JqFFBR0y9fL8TBSWbo8YU3BSzKRznAK9NhX790foLRauOBTUstdy1XS/M3F1EUKl+lV HI2g== X-Gm-Message-State: AOAM532ToEVmvfkIsQOPSuYxdgrLw64CutYPb9fT9dFZmcdigzU6qRU5 KTTV445XHpKTS++Vp4rFscq9zqCogX7GYkV6tlTlUs4IIVFVUmzgUCTeFuxFctIb2pXSUILAeUe CnB5rLdeN36pz8q++ X-Received: by 2002:a17:906:c289:: with SMTP id r9mr33947322ejz.402.1600374009907; Thu, 17 Sep 2020 13:20:09 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyDzp8PFMMUGx71+4Le3zZryehPDfyMnG9pPkDd4mXk5NQGPGcOHdA4dd2xmMSXBewgaGbQLw== X-Received: by 2002:a17:906:c289:: with SMTP id r9mr33947301ejz.402.1600374009706; Thu, 17 Sep 2020 13:20:09 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk ([45.145.92.2]) by smtp.gmail.com with ESMTPSA id dt8sm551547ejc.113.2020.09.17.13.20.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Sep 2020 13:20:08 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 2C7DE183A91; Thu, 17 Sep 2020 22:20:07 +0200 (CEST) Subject: [PATCH bpf-next v6 06/10] 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: Thu, 17 Sep 2020 22:20:07 +0200 Message-ID: <160037400712.28970.6100042329111941661.stgit@toke.dk> In-Reply-To: <160037400056.28970.7647821897296177963.stgit@toke.dk> References: <160037400056.28970.7647821897296177963.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 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 9228af9917a8..55f7b2ba1cbd 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -3860,7 +3860,14 @@ 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->tgt_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;