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 61107C4167E for ; Wed, 6 Apr 2022 00:10:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1453043AbiDEXrG (ORCPT ); Tue, 5 Apr 2022 19:47:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37372 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1577684AbiDEXMk (ORCPT ); Tue, 5 Apr 2022 19:12:40 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C72D8FCBC3 for ; Tue, 5 Apr 2022 14:44:21 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-2eb5d4fbd54so4829467b3.4 for ; Tue, 05 Apr 2022 14:44:21 -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=6NblM4DdSDjYKjDgLxEintAgK2IySwji0MbdGVjQAJ0=; b=aH7t3UmNuSMetoAxnT29hxQBjyn++fuJ7enCmtqyWIsfGhMm81NfSU5Nsxn6Fj9iuA TD7F3D5JrZ9gjaADebR/1Y6cS6NJneMk4y3euudNGGK4sQfKW+8r/CwY7VbgYJDbgqLA Hn+nTh34dLgSC5vLlYbRCxxi0ln6Fw6i/Ba8vnN9S+9E8McgZTlcpLsmMVQz5ER5pNYW rQHwOYEx9T/ZvNJfJHXwlzP0ZGC6PMD8wlYPt11XffIgFhYO89O4en2PzT/qLTkyzX9p 6Cfv7Spx/dXn5IbU95dJzaEYQHoj/3xpDXcOJt9GLg93KSMeaMqD5u+FaMYQeRL0Nzej JKUA== 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=6NblM4DdSDjYKjDgLxEintAgK2IySwji0MbdGVjQAJ0=; b=tLxMPn7UaPUqYFysYBTf+Ilb0NCih+4+pzkmox0XrJxd7wKzblgcTcm9vgi44XuXe7 TjSQvVCf8cSDM7ENojvPdcGWOfnkBklC4GKkaUcwvwPwbnzqc5XsFLZ+UFEFNXL5dWbp DPkzjQHmCNkC9IPlOXUCaLhqhhIHG2bA+MnxbgHzRzPzEIGpLou4Ug13A1bMTsYV0jih usVul8ELLBUzOqfaQ4KxuBHrrMa4yqrn7Pi9JBMf+FdFPnNDl+kYH3CMJdL3Db3/CayV 0AogHLLKnilCDCfJLas0jyncfxXyypFrJ5x3W2lGa3CR2WrRsX7z9icAlEJ5MsgWBYy+ B/kQ== X-Gm-Message-State: AOAM533Z88vL+VMDFd/5XEWC9Y6WMle+ky4I50wLZIxy050wUBHgdph8 vzZJ67yg9WKB313hizAsGjuiIT4= X-Google-Smtp-Source: ABdhPJz3bIH4Nxzw2caA4SgqgSA/xVwcc5VpbPucgbV0dvxX8YFSZFFqtXVW0z6sHMfbuDac/SI7xW8= X-Received: from sdf2.svl.corp.google.com ([2620:15c:2c4:201:73b5:ffab:2024:2901]) (user=sdf job=sendgmr) by 2002:a81:b288:0:b0:2d6:39d5:31a1 with SMTP id q130-20020a81b288000000b002d639d531a1mr4504807ywh.506.1649195035035; Tue, 05 Apr 2022 14:43:55 -0700 (PDT) Date: Tue, 5 Apr 2022 14:43:39 -0700 In-Reply-To: <20220405214342.1968262-1-sdf@google.com> Message-Id: <20220405214342.1968262-5-sdf@google.com> Mime-Version: 1.0 References: <20220405214342.1968262-1-sdf@google.com> X-Mailer: git-send-email 2.35.1.1094.g7c7d902a7c-goog Subject: [PATCH bpf-next v2 4/7] bpf: allow writing to a subset of sock fields from lsm progtype 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 For now, allow only the obvious ones, like sk_priority and sk_mark. Signed-off-by: Stanislav Fomichev --- kernel/bpf/bpf_lsm.c | 58 +++++++++++++++++++++++++++++++++++++++++++ kernel/bpf/verifier.c | 3 ++- 2 files changed, 60 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c index 8b948ec9ab73..cc13da18d8b3 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c @@ -332,7 +332,65 @@ bool bpf_lsm_is_sleepable_hook(u32 btf_id) const struct bpf_prog_ops lsm_prog_ops = { }; +static int lsm_btf_struct_access(struct bpf_verifier_log *log, + const struct btf *btf, + const struct btf_type *t, int off, + int size, enum bpf_access_type atype, + u32 *next_btf_id, + enum bpf_type_flag *flag) +{ + const struct btf_type *sock_type; + struct btf *btf_vmlinux; + s32 type_id; + size_t end; + + if (atype == BPF_READ) + return btf_struct_access(log, btf, t, off, size, atype, next_btf_id, + flag); + + btf_vmlinux = bpf_get_btf_vmlinux(); + if (!btf_vmlinux) { + bpf_log(log, "no vmlinux btf\n"); + return -EOPNOTSUPP; + } + + type_id = btf_find_by_name_kind(btf_vmlinux, "sock", BTF_KIND_STRUCT); + if (type_id < 0) { + bpf_log(log, "'struct sock' not found in vmlinux btf\n"); + return -EINVAL; + } + + sock_type = btf_type_by_id(btf_vmlinux, type_id); + + if (t != sock_type) { + bpf_log(log, "only 'struct sock' writes are supported\n"); + return -EACCES; + } + + switch (off) { + case bpf_ctx_range(struct sock, sk_priority): + end = offsetofend(struct sock, sk_priority); + break; + case bpf_ctx_range(struct sock, sk_mark): + end = offsetofend(struct sock, sk_mark); + break; + default: + bpf_log(log, "no write support to 'struct sock' at off %d\n", off); + return -EACCES; + } + + if (off + size > end) { + bpf_log(log, + "write access at off %d with size %d beyond the member of 'struct sock' ended at %zu\n", + off, size, end); + return -EACCES; + } + + return NOT_INIT; +} + const struct bpf_verifier_ops lsm_verifier_ops = { .get_func_proto = bpf_lsm_func_proto, .is_valid_access = btf_ctx_access, + .btf_struct_access = lsm_btf_struct_access, }; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 1d2f2e7babb2..d42ee0033755 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -12843,7 +12843,8 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) insn->code = BPF_LDX | BPF_PROBE_MEM | BPF_SIZE((insn)->code); env->prog->aux->num_exentries++; - } else if (resolve_prog_type(env->prog) != BPF_PROG_TYPE_STRUCT_OPS) { + } else if (resolve_prog_type(env->prog) != BPF_PROG_TYPE_STRUCT_OPS && + resolve_prog_type(env->prog) != BPF_PROG_TYPE_LSM) { verbose(env, "Writes through BTF pointers are not allowed\n"); return -EINVAL; } -- 2.35.1.1094.g7c7d902a7c-goog