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 30C1BC433EF for ; Fri, 29 Apr 2022 21:16:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236580AbiD2VTh (ORCPT ); Fri, 29 Apr 2022 17:19:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38402 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237437AbiD2VT2 (ORCPT ); Fri, 29 Apr 2022 17:19:28 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B4E287C159 for ; Fri, 29 Apr 2022 14:16:07 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id o64-20020a257343000000b006483069a28aso8503010ybc.3 for ; Fri, 29 Apr 2022 14:16:07 -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=UtPIgzvmBvRhCMQR/+L9Uukkz10/65B1dscx6ceVu9Y=; b=aAEj+4SbNZUq+5SDn5KgQ240sG8teV88Ceg2OBGMpYsLvcTvQpKutnFc3oYCmMIi+2 O1Vpf0bxH31bRe0Jjs1EFG6iKzgoFYpGcWqNEQVWkjfNhSYVaS33/uL1NgXi9Yh06gIN XnyHSZl30A+l3YrGAgbZz4WDR/nqHtufCQRg1Dtw9wLKg8VR68RA6W5UEIU+9Iv4XKMj MAOYmMkvMJ+TTw2Iq7f4ErzTeEhtwQZNIgfHaYdGy89mVC7tkCAE4rbztBpLQZcUGLgY gOg5U+q50DPykAVtAzjbiPd0ALRvwGpPvImDrzRF6oLSLesL6RBc6PaKmXviWuVake/8 uN/A== 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=UtPIgzvmBvRhCMQR/+L9Uukkz10/65B1dscx6ceVu9Y=; b=PhG2YuwfEu6To4IZkMyA5BAy1AfdBT8NRVmeun5s/NGJGz2NYVvgBfFtOkJubfmR0Q 5CZcKEuN2k1q1nQr7YuwHA/rnQbT/4rziPX9dKe7aqA1tCaZUfEdGKRfuw6RYu3/VTK4 T5NwkHcMfHu8o0gRSqqxswz/ly6SpVn7DzKdSsZg5xNtDtXmUhNcgogs++l1gvM4rzrG uBvQG+omU4oZ+HhYz9CcsbwOWUzjSIgChirEBQVu3NehIo9CDFGjG3lOWDGIwvWSS4/t w8D/qfYPxT3A3D/oxQd5s14EzgblKObEifGBaRUCwrCiWy/CeKk9YK0oX1Uh2u6Swbvf dSjQ== X-Gm-Message-State: AOAM533lUYWlNM5GoH+/hTepdj+g6a0UVZGkYdMGxoKT5FMeXzfhfAA6 obcbg6ksOjGQ55wNrh+6Tha9bfo= X-Google-Smtp-Source: ABdhPJyGzLv7QMHut2i0w0L2i2aezsPjsOVrMf91A8ECDoLZpaeNrfy9wxQ59h/yT3z8gR34uJZnT0E= X-Received: from sdf2.svl.corp.google.com ([2620:15c:2c4:201:b0cc:7605:1029:2d96]) (user=sdf job=sendgmr) by 2002:a25:ed08:0:b0:648:8b96:cb2c with SMTP id k8-20020a25ed08000000b006488b96cb2cmr1426804ybh.370.1651266966911; Fri, 29 Apr 2022 14:16:06 -0700 (PDT) Date: Fri, 29 Apr 2022 14:15:40 -0700 In-Reply-To: <20220429211540.715151-1-sdf@google.com> Message-Id: <20220429211540.715151-11-sdf@google.com> Mime-Version: 1.0 References: <20220429211540.715151-1-sdf@google.com> X-Mailer: git-send-email 2.36.0.464.gb9c8b46e94-goog Subject: [PATCH bpf-next v6 10/10] 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. Add new ldx_offset fixups to lookup the offset of struct field. Allow using test.kfunc regardless of prog_type. One interesting thing here is that the verifier doesn't really force me to add NULL checks anywhere :-/ Signed-off-by: Stanislav Fomichev --- tools/testing/selftests/bpf/test_verifier.c | 54 ++++++++++++++++++- .../selftests/bpf/verifier/lsm_cgroup.c | 34 ++++++++++++ 2 files changed, 87 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/bpf/verifier/lsm_cgroup.c diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index 372579c9f45e..49961492cbd4 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -75,6 +75,12 @@ struct kfunc_btf_id_pair { int insn_idx; }; +struct ldx_offset { + const char *strct; + const char *field; + int insn_idx; +}; + struct bpf_test { const char *descr; struct bpf_insn insns[MAX_INSNS]; @@ -103,6 +109,7 @@ struct bpf_test { int fixup_map_timer[MAX_FIXUPS]; int fixup_map_kptr[MAX_FIXUPS]; struct kfunc_btf_id_pair fixup_kfunc_btf_id[MAX_FIXUPS]; + struct ldx_offset fixup_ldx[MAX_FIXUPS]; /* Expected verifier log output for result REJECT or VERBOSE_ACCEPT. * Can be a tab-separated sequence of expected strings. An empty string * means no log verification. @@ -799,6 +806,7 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type, int *fixup_map_timer = test->fixup_map_timer; int *fixup_map_kptr = test->fixup_map_kptr; struct kfunc_btf_id_pair *fixup_kfunc_btf_id = test->fixup_kfunc_btf_id; + struct ldx_offset *fixup_ldx = test->fixup_ldx; if (test->fill_helper) { test->fill_insns = calloc(MAX_TEST_INSNS, sizeof(struct bpf_insn)); @@ -1018,6 +1026,50 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type, fixup_kfunc_btf_id++; } while (fixup_kfunc_btf_id->kfunc); } + + if (fixup_ldx->strct) { + const struct btf_member *memb; + const struct btf_type *tp; + const char *name; + struct btf *btf; + int btf_id; + int off; + int i; + + btf = btf__load_vmlinux_btf(); + + do { + off = -1; + if (!btf) + goto next_ldx; + + btf_id = btf__find_by_name_kind(btf, + fixup_ldx->strct, + BTF_KIND_STRUCT); + if (btf_id < 0) + goto next_ldx; + + 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(fixup_ldx->field, name) == 0) { + off = memb->offset / 8; + break; + } + memb++; + } + +next_ldx: + prog[fixup_ldx->insn_idx].off = off; + fixup_ldx++; + + } while (fixup_ldx->strct); + + btf__free(btf); + } } struct libcap { @@ -1182,7 +1234,7 @@ static void do_test_single(struct bpf_test *test, bool unpriv, opts.log_level = 4; opts.prog_flags = pflags; - if (prog_type == BPF_PROG_TYPE_TRACING && test->kfunc) { + if (test->kfunc) { int attach_btf_id; attach_btf_id = libbpf_find_vmlinux_btf_id(test->kfunc, diff --git a/tools/testing/selftests/bpf/verifier/lsm_cgroup.c b/tools/testing/selftests/bpf/verifier/lsm_cgroup.c new file mode 100644 index 000000000000..af0efe783511 --- /dev/null +++ b/tools/testing/selftests/bpf/verifier/lsm_cgroup.c @@ -0,0 +1,34 @@ +#define SK_WRITABLE_FIELD(tp, field, size, res) \ +{ \ + .descr = field, \ + .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, 0), \ + /* r2 = *(u64 *)(r1 + offsetof(struct sock, )) */ \ + BPF_LDX_MEM(size, BPF_REG_2, BPF_REG_1, 0), \ + /* *(u64 *)(r1 + offsetof(struct sock, )) = r2 */ \ + BPF_STX_MEM(size, BPF_REG_1, BPF_REG_2, 0), \ + BPF_MOV64_IMM(BPF_REG_0, 1), \ + BPF_EXIT_INSN(), \ + }, \ + .result = res, \ + .errstr = res ? "no write support to 'struct sock' at off" : "", \ + .prog_type = BPF_PROG_TYPE_LSM, \ + .expected_attach_type = BPF_LSM_CGROUP, \ + .kfunc = "socket_post_create", \ + .fixup_ldx = { \ + { "socket", "sk", 1 }, \ + { tp, field, 2 }, \ + { tp, field, 3 }, \ + }, \ +} + +SK_WRITABLE_FIELD("sock_common", "skc_family", BPF_H, REJECT), +SK_WRITABLE_FIELD("sock", "sk_sndtimeo", BPF_DW, REJECT), +SK_WRITABLE_FIELD("sock", "sk_priority", BPF_W, ACCEPT), +SK_WRITABLE_FIELD("sock", "sk_mark", BPF_W, ACCEPT), +SK_WRITABLE_FIELD("sock", "sk_pacing_rate", BPF_DW, REJECT), + +#undef SK_WRITABLE_FIELD -- 2.36.0.464.gb9c8b46e94-goog