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 591C2C43219 for ; Fri, 29 Apr 2022 21:16:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236338AbiD2VT2 (ORCPT ); Fri, 29 Apr 2022 17:19:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38212 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236754AbiD2VTZ (ORCPT ); Fri, 29 Apr 2022 17:19:25 -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 41E708073A for ; Fri, 29 Apr 2022 14:15:58 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id o64-20020a257343000000b006483069a28aso8502669ybc.3 for ; Fri, 29 Apr 2022 14:15:58 -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=ZAfKPNLYcqo0cDIFYU+gDT4lGoQqRciZy76yQyksGOk=; b=Jn02PSlAt7hRdUC4/C7UYX2Yp/CiotucNpXs4yFDhhG7mR3/5HKAW6M7uCyLgRDstm bUigB37Iy7b5XnTmNM5UOfGVv0p9D2XwRqtHJTVuPU6C9X+fiP1WIJD1uUS06rf9rE0P N++AXZD+r3tGrWqy9oEI4RnigbdQCazfLAY73JtpjthRVtcxDfXA5eFldCHUz0PVMchi nKhcOaRCtL5YWWd2NvTV4oK6z8xH5zGxZC1fmK+Jq5INtmCKcUQJiFRULPtpu0YFpaDM zce71GDqYhvisS1tskyjtz2tOAtjAN7Ex9M6EAefmMfkIcnHvhUeIRT44tgBlsUt45Kg fBkQ== 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=ZAfKPNLYcqo0cDIFYU+gDT4lGoQqRciZy76yQyksGOk=; b=vLuW3V/1A2gAb1u5nmrlsMRflgyFh0Bs79YVjDoz+ofrDvDw1nT4k03lPPEssLnzUH ttuD5MF1GBwpJOOwX0r5WqBxZJtv1zz/ckbN2h7oIkT6xrgVIAp86x4EaGbNpZo4d1XS /nsOQPgXO/Xy96oxK0UVG2ZErhItJepl/BpM+xYscmwZrOdddNZHluRZrNtt4sTlXAyG RFZxajLSUxiSkxO0YQ+lwjo3hxoWMJbVTUICC5tvg7C5a70GHiw+mD2fHEPKu+vJ++ag +q3nv5EiaeqWlPuI8wl2XjZ/f2Wlt7brL11siGYnCaTjHU9mIHwpvH3oUPj3KFvdl8Px kpJg== X-Gm-Message-State: AOAM532CrSQuHy2t+AT3OZ7S2tEzpPIoXgapyLjsPAfgAAxPr2NEoF90 zXCHBPZEafs/tkw+1AyeVyM1SM4= X-Google-Smtp-Source: ABdhPJwQwcdzZuWFq3lhlVYpgvCYZ/8qASglsvbF0JLfvjwZoqwvAYnX3MexsPbHuqbm+O9ZsZVp+SE= X-Received: from sdf2.svl.corp.google.com ([2620:15c:2c4:201:b0cc:7605:1029:2d96]) (user=sdf job=sendgmr) by 2002:a81:1545:0:b0:2f7:b6d6:c486 with SMTP id 66-20020a811545000000b002f7b6d6c486mr1244997ywv.261.1651266957393; Fri, 29 Apr 2022 14:15:57 -0700 (PDT) Date: Fri, 29 Apr 2022 14:15:36 -0700 In-Reply-To: <20220429211540.715151-1-sdf@google.com> Message-Id: <20220429211540.715151-7-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 06/10] 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 1079c747e061..64406d39e861 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c @@ -302,7 +302,65 @@ 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 99703d96c579..2ada6fd48638 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -13130,7 +13130,8 @@ 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; } -- 2.36.0.464.gb9c8b46e94-goog