From patchwork Mon Nov 28 07:26:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Viktor Malik X-Patchwork-Id: 13057094 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 47534C4167D for ; Mon, 28 Nov 2022 07:27:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229626AbiK1H1l (ORCPT ); Mon, 28 Nov 2022 02:27:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38166 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229895AbiK1H1i (ORCPT ); Mon, 28 Nov 2022 02:27:38 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 50FED13E22 for ; Sun, 27 Nov 2022 23:26:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1669620407; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=nG5eYstJ0nX/CY5OkDMZ+vp8vbyytdDbuM6xBU/t/Nc=; b=a6k/dxiAMyy5rk96FEYzngvy0cBnqJMRdTc62cvXSHIWn9+3kCW1GUylHm0h9v0UsIfDO4 mcP1zIc6jrOleMmVdgJ88ctqpo8Bu6/MHYQHX+z1hIS7sEi81nSBTC2CrmY+bq8oDclfz+ DdUlWiAfH7V6CvaVDqI4/KstJ9vf83g= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-446-3n_IvGO5P3CmKv-5cMUJiA-1; Mon, 28 Nov 2022 02:26:41 -0500 X-MC-Unique: 3n_IvGO5P3CmKv-5cMUJiA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 1AA6E802314; Mon, 28 Nov 2022 07:26:41 +0000 (UTC) Received: from ovpn-192-85.brq.redhat.com (ovpn-192-85.brq.redhat.com [10.40.192.85]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1E9A41415100; Mon, 28 Nov 2022 07:26:37 +0000 (UTC) From: Viktor Malik To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Viktor Malik Subject: [PATCH bpf-next 0/2] Fix attaching fentry/fexit/fmod_ret/lsm to modules Date: Mon, 28 Nov 2022 08:26:28 +0100 Message-Id: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net While working on bpftrace support for BTF in modules [1], I noticed that the verifier behaves incorrectly when attaching to fentry of multiple functions of the same name located in different modules (or in vmlinux). The reason for this is that if the target program is not specified, the verifier will search kallsyms for the trampoline address to attach to. The entire kallsyms is always searched, not respecting the module in which the function to attach to is located. This patch fixes the above issue by extracting the module name from the BTF of the attachment target (which must be specified) and by doing the search in kallsyms of the correct module. This also adds a new test in test_progs which tries to attach a program to fentry of two functions of the same name, one located in vmlinux and the other in bpf_testmod. Prior to the fix, the verifier would always use the vmlinux function address as the target trampoline, attempting to attach two functions to the same trampoline (which is prohibited). [1] https://github.com/iovisor/bpftrace/pull/2315 Viktor Malik (2): bpf: Fix attaching fentry/fexit/fmod_ret/lsm to modules bpf/selftests: Test fentry attachment to shadowed functions include/linux/btf.h | 1 + kernel/bpf/btf.c | 5 + kernel/bpf/verifier.c | 9 +- net/bpf/test_run.c | 5 + .../selftests/bpf/bpf_testmod/bpf_testmod.c | 7 + .../bpf/prog_tests/module_attach_shadow.c | 120 ++++++++++++++++++ 6 files changed, 146 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/module_attach_shadow.c