From mboxrd@z Thu Jan 1 00:00:00 1970 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 C1941C77B75 for ; Wed, 3 May 2023 00:43:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229482AbjECAnD (ORCPT ); Tue, 2 May 2023 20:43:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51412 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229441AbjECAnD (ORCPT ); Tue, 2 May 2023 20:43:03 -0400 Received: from out-12.mta1.migadu.com (out-12.mta1.migadu.com [95.215.58.12]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5C72F2D5F for ; Tue, 2 May 2023 17:43:01 -0700 (PDT) Message-ID: <00537b92-c8f8-e101-1016-0ee980b028f1@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1683074579; 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=EJ13LGXGBTkL9TON7tcsjC0SiX4e23j8lfeleOmYNH4=; b=KZlaSpA2JHI8BvCEGLHYkKHhcbL9cc3aEcyJ0ls14gHnyTXLrCtHVLp9XXSXSE7RYiUk5e Tq8pfhF4b3nSWZTZTPOAISUctT7rwDPhgIwpeaDCK8rB9YzI4mL+9wSBzA5UWWFPUVDwDz F6IHKGNax4QBZgEFgiKhxOibY++E7WQ= Date: Tue, 2 May 2023 17:42:56 -0700 MIME-Version: 1.0 Subject: Re: [PATCH bpf-next v3 2/4] selftests/bpf: Update EFAULT {g,s}etsockopt selftests Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Martin KaFai Lau To: Stanislav Fomichev Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, song@kernel.org, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, haoluo@google.com, jolsa@kernel.org, bpf@vger.kernel.org References: <20230501194825.2864150-1-sdf@google.com> <20230501194825.2864150-3-sdf@google.com> <9cc9a5f6-35cd-cfa3-8034-18dac9f20d6f@linux.dev> In-Reply-To: <9cc9a5f6-35cd-cfa3-8034-18dac9f20d6f@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 5/2/23 5:29 PM, Martin KaFai Lau wrote: > On 5/1/23 12:48 PM, Stanislav Fomichev wrote: >> Instead of assuming EFAULT, let's assume the BPF program's >> output is ignored. >> >> Remove "getsockopt: deny arbitrary ctx->retval" because it >> was actually testing optlen. We have separate set of tests >> for retval. >> >> Signed-off-by: Stanislav Fomichev >> --- >>   .../selftests/bpf/prog_tests/sockopt.c        | 98 +++++++++++++++++-- >>   1 file changed, 92 insertions(+), 6 deletions(-) >> >> diff --git a/tools/testing/selftests/bpf/prog_tests/sockopt.c >> b/tools/testing/selftests/bpf/prog_tests/sockopt.c >> index aa4debf62fc6..a7bc9dc93ce0 100644 >> --- a/tools/testing/selftests/bpf/prog_tests/sockopt.c >> +++ b/tools/testing/selftests/bpf/prog_tests/sockopt.c >> @@ -5,6 +5,10 @@ >>   static char bpf_log_buf[4096]; >>   static bool verbose; >> +#ifndef PAGE_SIZE >> +#define PAGE_SIZE 4096 >> +#endif >> + >>   enum sockopt_test_error { >>       OK = 0, >>       DENY_LOAD, >> @@ -273,10 +277,30 @@ static struct sockopt_test { >>           .error = EFAULT_GETSOCKOPT, >>       }, >>       { >> -        .descr = "getsockopt: deny arbitrary ctx->retval", >> +        .descr = "getsockopt: ignore >PAGE_SIZE optlen", >>           .insns = { >> -            /* ctx->retval = 123 */ >> -            BPF_MOV64_IMM(BPF_REG_0, 123), >> +            /* write 0xFF to the first optval byte */ >> + >> +            /* r6 = ctx->optval */ >> +            BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, >> +                    offsetof(struct bpf_sockopt, optval)), >> +            /* r2 = ctx->optval */ >> +            BPF_MOV64_REG(BPF_REG_2, BPF_REG_6), >> +            /* r6 = ctx->optval + 1 */ >> +            BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, 1), >> + >> +            /* r7 = ctx->optval_end */ >> +            BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_1, >> +                    offsetof(struct bpf_sockopt, optval_end)), >> + >> +            /* if (ctx->optval + 1 <= ctx->optval_end) { */ >> +            BPF_JMP_REG(BPF_JGT, BPF_REG_6, BPF_REG_7, 1), >> +            /* ctx->optval[0] = 0xF0 */ >> +            BPF_ST_MEM(BPF_B, BPF_REG_2, 0, 0xFF), >> +            /* } */ >> + >> +            /* ctx->retval = 0 */ >> +            BPF_MOV64_IMM(BPF_REG_0, 0), > > > This is an interesting test case. One more question just came to my mind, > does it make sense to also ignore the bpf-prog's 'ctx->retval = 0' in getsockopt > considering its optval change has already been ignored. Something like: > >     if (optval && (ctx.optlen > max_optlen || ctx.optlen < 0)) { >         if (orig_optlen > PAGE_SIZE && ctx.optlen >= 0) { >             pr_info_once("bpf getsockopt: ignoring program buffer with > optlen=%d (max_optlen=%d)\n", >                      ctx.optlen, max_optlen); >             ret = retval; >                         goto out; >                 } >                 ret = -EFAULT; >                 goto out; >         } Previous one has indentation off. Meaning to be: if (optval && (ctx.optlen > max_optlen || ctx.optlen < 0)) { if (orig_optlen > PAGE_SIZE && ctx.optlen >= 0) { pr_info_once("bpf getsockopt: ignoring program buffer with optlen=%d (max_optlen=%d)\n", ctx.optlen, max_optlen); ret = retval; goto out; } ret = -EFAULT; goto out; } > > >>               BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0, >>                       offsetof(struct bpf_sockopt, retval)), >> @@ -287,9 +311,10 @@ static struct sockopt_test { >>           .attach_type = BPF_CGROUP_GETSOCKOPT, >>           .expected_attach_type = BPF_CGROUP_GETSOCKOPT, >> -        .get_optlen = 64, >> - >> -        .error = EFAULT_GETSOCKOPT, >> +        .get_level = 1234, >> +        .get_optname = 5678, >> +        .get_optval = {}, /* the changes are ignored */ >> +        .get_optlen = PAGE_SIZE + 1, >>           } >> +        if (optlen > sizeof(test->get_optval)) >> +            optlen = sizeof(test->get_optval); >> + >>           if (memcmp(optval, test->get_optval, optlen) != 0) { >>               errno = 0; >>               log_err("getsockopt returned unexpected optval"); >