From patchwork Mon Nov 16 21:17:32 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Xu X-Patchwork-Id: 11910867 X-Patchwork-Delegate: bpf@iogearbox.net 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,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, USER_AGENT_GIT autolearn=ham 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 A8BCDC63697 for ; Mon, 16 Nov 2020 21:17:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5CC412224F for ; Mon, 16 Nov 2020 21:17:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=dxuuu.xyz header.i=@dxuuu.xyz header.b="ZyeRn45K"; dkim=temperror (0-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="Ro8PCpDM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728018AbgKPVRw (ORCPT ); Mon, 16 Nov 2020 16:17:52 -0500 Received: from wout3-smtp.messagingengine.com ([64.147.123.19]:56501 "EHLO wout3-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727796AbgKPVRu (ORCPT ); Mon, 16 Nov 2020 16:17:50 -0500 Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailout.west.internal (Postfix) with ESMTP id 865D6D3D; Mon, 16 Nov 2020 16:17:49 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute3.internal (MEProxy); Mon, 16 Nov 2020 16:17:50 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dxuuu.xyz; h= from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; s=fm2; bh=e+edu/6Q4wBbY YEXH8t+dOvgpbiWbWHOudleytAG4Gc=; b=ZyeRn45KhNZPyKfrFOUYMW2Z1tIcd G/AdXINYADc+YmzDKlYxZ1rjCgpV9GsEKOGjPd0OLHIlbkwo5JbtmcAayg9+F1H0 IQyrffwlNAjSFayyN4TibHMUxTMBjT5e6BFcMjhcwgjwXkZ4A9RGNzQ53EiKNXRo Cpeybi7jhD90EzeuUfK4WjHY0iF7OO9/6lzbPFy8sjM1yPditmiiVn3Ul0OBg4No KRHAJBCrH6D/DBczToqxLHVXfOvuASicidfwUmnjpxbzskXy9zff+O960DJYkvA0 WLmFEF88wKlGGy/iVKSCcRtiT1To+/mEnxgAFpJvg6CWh+6aSNrgkTWSQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:date:from :in-reply-to:message-id:mime-version:references:subject:to :x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm1; bh=e+edu/6Q4wBbYYEXH8t+dOvgpbiWbWHOudleytAG4Gc=; b=Ro8PCpDM ll0q3vvStJBNmj7mx0Bj3AdKGhT/5eMakCu+ZIaV2LIsvJOxJQ+2S49denIBBGjz 6W+nxbIPXlHRiaMqEtki5ne04tnI6qeZenBTNFrLpW0bWFtcJz/vHC8JfiTIzCew EhvgMuvZHOwM/DM7r6m7eiYFq2xyOrPYySs6TGfeEN0Qzh8fZWxqH1pvhLPC7vB3 ByFhhgjtA551KC5QXCcxNta+P9kSl82g1H5Y8NiH6ucAdTGAm2iiQdH5FV5GWzr7 X0XK2LUB1yj/CJwzR1v6nzvX7/41RqS8Ym4cgtOIYW4Uy5Q11W7CvxFgAhPPu2KH jcLZJ5ozgfHGrw== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedujedrudefuddgudegkecutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfgh necuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd enfghrlhcuvffnffculddvfedmnecujfgurhephffvufffkffojghfggfgsedtkeertder tddtnecuhfhrohhmpeffrghnihgvlhcuighuuceougiguhesugiguhhuuhdrgiihiieqne cuggftrfgrthhtvghrnhepgfekudelkefhteevhfeggfdvgeefjeefgfeuvddutdfhgffg hfehtdeuueetfeeinecukfhppeeiledrudekuddruddthedrieegnecuvehluhhsthgvrh fuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomhepugiguhesugiguhhuuhdrgiih ii X-ME-Proxy: Received: from localhost.localdomain (c-69-181-105-64.hsd1.ca.comcast.net [69.181.105.64]) by mail.messagingengine.com (Postfix) with ESMTPA id 0A9383280067; Mon, 16 Nov 2020 16:17:47 -0500 (EST) From: Daniel Xu To: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, songliubraving@fb.com, andrii.nakryiko@gmail.com, torvalds@linux-foundation.org Cc: Daniel Xu , kernel-team@fb.com, Andrii Nakryiko Subject: [PATCH bpf v6 2/2] selftest/bpf: Test bpf_probe_read_user_str() strips trailing bytes after NUL Date: Mon, 16 Nov 2020 13:17:32 -0800 Message-Id: X-Mailer: git-send-email 2.29.2 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Previously, bpf_probe_read_user_str() could potentially overcopy the trailing bytes after the NUL due to how do_strncpy_from_user() does the copy in long-sized strides. The issue has been fixed in the previous commit. This commit adds a selftest that ensures we don't regress bpf_probe_read_user_str() again. Acked-by: Song Liu Acked-by: Andrii Nakryiko Signed-off-by: Daniel Xu --- .../bpf/prog_tests/probe_read_user_str.c | 71 +++++++++++++++++++ .../bpf/progs/test_probe_read_user_str.c | 25 +++++++ 2 files changed, 96 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/probe_read_user_str.c create mode 100644 tools/testing/selftests/bpf/progs/test_probe_read_user_str.c diff --git a/tools/testing/selftests/bpf/prog_tests/probe_read_user_str.c b/tools/testing/selftests/bpf/prog_tests/probe_read_user_str.c new file mode 100644 index 000000000000..e419298132b5 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/probe_read_user_str.c @@ -0,0 +1,71 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include "test_probe_read_user_str.skel.h" + +static const char str1[] = "mestring"; +static const char str2[] = "mestringalittlebigger"; +static const char str3[] = "mestringblubblubblubblubblub"; + +static int test_one_str(struct test_probe_read_user_str *skel, const char *str, + size_t len) +{ + int err, duration = 0; + char buf[256]; + + /* Ensure bytes after string are ones */ + memset(buf, 1, sizeof(buf)); + memcpy(buf, str, len); + + /* Give prog our userspace pointer */ + skel->bss->user_ptr = buf; + + /* Trigger tracepoint */ + usleep(1); + + /* Did helper fail? */ + if (CHECK(skel->bss->ret < 0, "prog_ret", "prog returned: %ld\n", + skel->bss->ret)) + return 1; + + /* Check that string was copied correctly */ + err = memcmp(skel->bss->buf, str, len); + if (CHECK(err, "memcmp", "prog copied wrong string")) + return 1; + + /* Now check that no extra trailing bytes were copied */ + memset(buf, 0, sizeof(buf)); + err = memcmp(skel->bss->buf + len, buf, sizeof(buf) - len); + if (CHECK(err, "memcmp", "trailing bytes were not stripped")) + return 1; + + return 0; +} + +void test_probe_read_user_str(void) +{ + struct test_probe_read_user_str *skel; + int err, duration = 0; + + skel = test_probe_read_user_str__open_and_load(); + if (CHECK(!skel, "test_probe_read_user_str__open_and_load", + "skeleton open and load failed\n")) + return; + + /* Give pid to bpf prog so it doesn't read from anyone else */ + skel->bss->pid = getpid(); + + err = test_probe_read_user_str__attach(skel); + if (CHECK(err, "test_probe_read_user_str__attach", + "skeleton attach failed: %d\n", err)) + goto out; + + if (test_one_str(skel, str1, sizeof(str1))) + goto out; + if (test_one_str(skel, str2, sizeof(str2))) + goto out; + if (test_one_str(skel, str3, sizeof(str3))) + goto out; + +out: + test_probe_read_user_str__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/test_probe_read_user_str.c b/tools/testing/selftests/bpf/progs/test_probe_read_user_str.c new file mode 100644 index 000000000000..3ae398b75dcd --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_probe_read_user_str.c @@ -0,0 +1,25 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include + +#include + +pid_t pid = 0; +long ret = 0; +void *user_ptr = 0; +char buf[256] = {}; + +SEC("tracepoint/syscalls/sys_enter_nanosleep") +int on_write(void *ctx) +{ + if (pid != (bpf_get_current_pid_tgid() >> 32)) + return 0; + + ret = bpf_probe_read_user_str(buf, sizeof(buf), user_ptr); + + return 0; +} + +char _license[] SEC("license") = "GPL";