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 1AD39C4167B for ; Wed, 18 May 2022 22:57:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231288AbiERW5L (ORCPT ); Wed, 18 May 2022 18:57:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38822 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231598AbiERW4d (ORCPT ); Wed, 18 May 2022 18:56:33 -0400 Received: from mail-pl1-x64a.google.com (mail-pl1-x64a.google.com [IPv6:2607:f8b0:4864:20::64a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DEA656CF50 for ; Wed, 18 May 2022 15:55:57 -0700 (PDT) Received: by mail-pl1-x64a.google.com with SMTP id i16-20020a170902cf1000b001540b6a09e3so1598019plg.0 for ; Wed, 18 May 2022 15:55:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=2ifMzJdcStY/5O5m6nh5Ja6Hm2K26IpKO1V8xVAoPAA=; b=YXhPrApKNkUQKwlm2mGARh4GMIFWll80cKgOCU0MXAqSBAntXKsil1cubi+/1mhEb8 Fu9CHujxwdnmwT82yz6cIzjBjLdWfyuJIJu9cNn1g4a1IOB900Lb5eiAIA4YQnPGlYto tnP8wtQaFattfbLovkQChzNWJ7Ju6sL/n97UnxifSCZfwpse/dAIKN5Thfe6JReM2lhg RFudkvkniz1nnpDb9w7AdH7NQcfdMvFoWeuxqw6EUc4sOfPvtFh5PldUQJCfppG1Ad01 DYVZVvxx5D6wYRk4Tym8g/6G7pdK+X3/jo8GHoHGdC+UbTiQwaskhDz57+15AnO7r3B8 HCIg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=2ifMzJdcStY/5O5m6nh5Ja6Hm2K26IpKO1V8xVAoPAA=; b=gaMJtrrta9lcoOLvHo2GefWUWD6ZO5fOoWcn0q659ePeqQO2XKoIIpiOJyC19G8Sl+ MjjON5eLgFfQcUpc3MJUZguH2oWAUAtl2FG+2Bz4buNoWprJ7SiGm2PI6s+zqiDWwIBz ME2JRtqoGT1XbGah6CDLh03q6SNYZk4oB8+1lzdlWcv/OLse+EX36bUzTjW4wrs5xgBF 3EcV11TFYxlIR+5rkXA6OIqhxVipLDXb7+9OkKAtJ0myNFmyfC/dn1NhTtSlhBPSXiaD /bDOcIn1A+h9p2l4wU3IvUFk7efqYD4QYREKrB4/IALSiw/HViF3KTLixmQ31xgUg/1u v4Zw== X-Gm-Message-State: AOAM533efVR6UlMwYRiPuPrXCdP2AsQc7g0dUrbyY4ILOf6G9qRGVVpi vgA4bUNhV/Qkgjtm8NUfU9gYEF0= X-Google-Smtp-Source: ABdhPJw0k7LpVBazAYEoSnhzKwo955ffrSG+h/J0BWzBQFCMtKcK8ga39AoNhoSey4mBzYj/Qm0dpz0= X-Received: from sdf2.svl.corp.google.com ([2620:15c:2c4:201:f763:3448:2567:bf00]) (user=sdf job=sendgmr) by 2002:a17:90b:4b02:b0:1df:d622:dd07 with SMTP id lx2-20020a17090b4b0200b001dfd622dd07mr276056pjb.160.1652914557091; Wed, 18 May 2022 15:55:57 -0700 (PDT) Date: Wed, 18 May 2022 15:55:31 -0700 In-Reply-To: <20220518225531.558008-1-sdf@google.com> Message-Id: <20220518225531.558008-12-sdf@google.com> Mime-Version: 1.0 References: <20220518225531.558008-1-sdf@google.com> X-Mailer: git-send-email 2.36.1.124.g0e6072fb45-goog Subject: [PATCH bpf-next v7 11/11] selftests/bpf: verify lsm_cgroup struct sock access From: Stanislav Fomichev To: netdev@vger.kernel.org, bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, Stanislav Fomichev Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org sk_priority & sk_mark are writable, the rest is readonly. One interesting thing here is that the verifier doesn't really force me to add NULL checks anywhere :-/ Signed-off-by: Stanislav Fomichev --- .../selftests/bpf/prog_tests/lsm_cgroup.c | 69 +++++++++++++++++++ 1 file changed, 69 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/lsm_cgroup.c b/tools/testing/selftests/bpf/prog_tests/lsm_cgroup.c index 29292ec40343..64b6830e03f5 100644 --- a/tools/testing/selftests/bpf/prog_tests/lsm_cgroup.c +++ b/tools/testing/selftests/bpf/prog_tests/lsm_cgroup.c @@ -270,8 +270,77 @@ static void test_lsm_cgroup_functional(void) lsm_cgroup__destroy(skel); } +static int field_offset(const char *type, const char *field) +{ + const struct btf_member *memb; + const struct btf_type *tp; + const char *name; + struct btf *btf; + int btf_id; + int i; + + btf = btf__load_vmlinux_btf(); + if (!btf) + return -1; + + btf_id = btf__find_by_name_kind(btf, type, BTF_KIND_STRUCT); + if (btf_id < 0) + return -1; + + tp = btf__type_by_id(btf, btf_id); + memb = btf_members(tp); + + for (i = 0; i < btf_vlen(tp); i++) { + name = btf__name_by_offset(btf, + memb->name_off); + if (strcmp(field, name) == 0) + return memb->offset / 8; + memb++; + } + + return -1; +} + +static bool sk_writable_field(const char *type, const char *field, int size) +{ + LIBBPF_OPTS(bpf_prog_load_opts, opts, + .expected_attach_type = BPF_LSM_CGROUP); + struct bpf_insn insns[] = { + /* r1 = *(u64 *)(r1 + 0) */ + BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1, 0), + /* r1 = *(u64 *)(r1 + offsetof(struct socket, sk)) */ + BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1, field_offset("socket", "sk")), + /* r2 = *(u64 *)(r1 + offsetof(struct sock, )) */ + BPF_LDX_MEM(size, BPF_REG_2, BPF_REG_1, field_offset(type, field)), + /* *(u64 *)(r1 + offsetof(struct sock, )) = r2 */ + BPF_STX_MEM(size, BPF_REG_1, BPF_REG_2, field_offset(type, field)), + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_EXIT_INSN(), + }; + int fd; + + opts.attach_btf_id = libbpf_find_vmlinux_btf_id("socket_post_create", + opts.expected_attach_type); + + fd = bpf_prog_load(BPF_PROG_TYPE_LSM, NULL, "GPL", insns, ARRAY_SIZE(insns), &opts); + if (fd >= 0) + close(fd); + return fd >= 0; +} + +static void test_lsm_cgroup_access(void) +{ + ASSERT_FALSE(sk_writable_field("sock_common", "skc_family", BPF_H), "skc_family"); + ASSERT_FALSE(sk_writable_field("sock", "sk_sndtimeo", BPF_DW), "sk_sndtimeo"); + ASSERT_TRUE(sk_writable_field("sock", "sk_priority", BPF_W), "sk_priority"); + ASSERT_TRUE(sk_writable_field("sock", "sk_mark", BPF_W), "sk_mark"); + ASSERT_FALSE(sk_writable_field("sock", "sk_pacing_rate", BPF_DW), "sk_pacing_rate"); +} + void test_lsm_cgroup(void) { if (test__start_subtest("functional")) test_lsm_cgroup_functional(); + if (test__start_subtest("access")) + test_lsm_cgroup_access(); } -- 2.36.1.124.g0e6072fb45-goog