From patchwork Fri Sep 25 21:25:05 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: 11800843 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 0943C6CA for ; Fri, 25 Sep 2020 21:25:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D5E1720758 for ; Fri, 25 Sep 2020 21:25:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="XCo4khqC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729620AbgIYVZi (ORCPT ); Fri, 25 Sep 2020 17:25:38 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:30217 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729636AbgIYVZM (ORCPT ); Fri, 25 Sep 2020 17:25:12 -0400 Dkim-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1601069110; 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=Xdjze0+H0wQC0BCSe+88MMo64OYING8Jcj/dCM8lzrg=; b=XCo4khqCDqUtGloVJUNRlcIVI8l4JnKQCx+NhRA6jfY5kkDwMlne+pvzrmC0VCqT06KQW+ gKYDgfiJpJRqhKiwmunkGyw30dLoYz74xy1Td0zo0znm0ZaVHvjhVOrTn2lm2lXmgXOgvS i0xVzrJh0+Ztt04reMfeStUdSvSIzw4= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-21-1_id5fUWOzinSY4cn1mCeg-1; Fri, 25 Sep 2020 17:25:08 -0400 X-MC-Unique: 1_id5fUWOzinSY4cn1mCeg-1 Received: by mail-wr1-f72.google.com with SMTP id b7so1582586wrn.6 for ; Fri, 25 Sep 2020 14:25:08 -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=Xdjze0+H0wQC0BCSe+88MMo64OYING8Jcj/dCM8lzrg=; b=R/I7OoE2wnPKsQ+iIQW2i20z1lrMt4Vm6+E5cuZe0NftTFJliF0JxWmzaqrUrs9dCg tR1on/AM7v1d2u80vR+mbNFkpTQMlkEaj/iHze7lcuzHdIXpCSjNeV8j4nc4TzT4xdrm oOQpnAJRQRmeR/mJ4KxU9mjTu17BNQnYzpNvxLWbSvYz1WAQcv3DzK4FxjjlPVao8tdC 14ntzxF7+j4mpo26/PTxlvZWPQO9+zG2ELelcsvmOWY/ArlKQ8knqEBs7C116o4tSb4q 5Z21zzTEuLZiUIYBzI8n75J6RRyvZVd6GwjUxWHdEFia81jhTZ9SEbJwT1m1yWlHDKOa qYgw== X-Gm-Message-State: AOAM533lItfV8PJ9oXi/XlU+ioORinEzF+evAkyOu60weJFaWTGTJOQS YVm9GgVX02AdeirI3WCG7DTctt+K1EiGpeXtgsOsl1J/YgqsssdX3uCTzpptD3+Iq6d/mRvzb4L Ggrc5GtpMHLpd X-Received: by 2002:a1c:23c9:: with SMTP id j192mr543416wmj.6.1601069107256; Fri, 25 Sep 2020 14:25:07 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyTE6eSafLE/wLFeOCFGZbFLV7X+JAfR+vtVrBbMfmjnnDiUVxHjooj/WEA5NjC41jFkhS5HQ== X-Received: by 2002:a1c:23c9:: with SMTP id j192mr543386wmj.6.1601069106826; Fri, 25 Sep 2020 14:25:06 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk ([2a0c:4d80:42:443::2]) by smtp.gmail.com with ESMTPSA id w7sm4120891wrm.92.2020.09.25.14.25.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 25 Sep 2020 14:25:06 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id E921C183C5B; Fri, 25 Sep 2020 23:25:05 +0200 (CEST) Subject: [PATCH bpf-next v9 06/11] 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: Fri, 25 Sep 2020 23:25:05 +0200 Message-ID: <160106910591.27725.1499697900366462609.stgit@toke.dk> In-Reply-To: <160106909952.27725.8383447127582216829.stgit@toke.dk> References: <160106909952.27725.8383447127582216829.stgit@toke.dk> User-Agent: StGit/0.23 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@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 faf57c6f8804..7fd4757a573d 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 (dst_prog) { - ret = btf_translate_to_vmlinux(log, btf, t, dst_prog->type, arg); + enum bpf_prog_type dst_type; + + if (dst_prog->type == BPF_PROG_TYPE_EXT) + dst_type = dst_prog->aux->saved_dst_prog_type; + else + dst_type = dst_prog->type; + + ret = btf_translate_to_vmlinux(log, btf, t, dst_type, arg); if (ret > 0) { info->btf_id = ret; return true;