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 3A1CBC433F5 for ; Mon, 28 Mar 2022 18:17:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245156AbiC1SSx (ORCPT ); Mon, 28 Mar 2022 14:18:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51122 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245152AbiC1SSk (ORCPT ); Mon, 28 Mar 2022 14:18:40 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 33CCB5D677 for ; Mon, 28 Mar 2022 11:16:57 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-2e5db04460cso124082977b3.17 for ; Mon, 28 Mar 2022 11:16:57 -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=/F5gfRvEdyS2sn1sTwI1ToLzIsHj+B5IxBw57Or4uew=; b=qKbS/lcm6IOmk2nmOLJcBt9knnggNfMBq/L8mhbLzfzGQCNfE6khn9pOn7ChUXR38b UZE0GpG/5FQ0blH7Ml3DxJky8ALTZIstpvsBEWVe7YeqhDRzRzWQhkmDpuqXeYL1xhzp oKxwbSBxYbi7mGvlqvAtjlCoWj/1EoNQBP2XU48ryqdJfobjXsJ1CdDLF1oLreizkZHe 8ZyELzZ0+8pEEq+IJxon3PCWNYfr+RNG+Yt3C97QiDipH7hBglW+C2cXwspvqfCX6LQl /zPHGaIHpGUeMvjYyLn/G1ZKU6kth3A5MWhOHl88IB5dm+nShe5k8/Eq0gLX3enklaRR FONg== 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=/F5gfRvEdyS2sn1sTwI1ToLzIsHj+B5IxBw57Or4uew=; b=1tEjvA28Y6NAUKzV3lZTR/ChezjfJCvRlmKcGP/UF+X3+j00iry8eoss397kkpAbuu G2bPvAMbt2jySka8eXKsqYlD+4RI6n/OO5PdWmdj1EE9UFbKtJM3rPlrhVwlcv72x5YD Ho+ePvmMdhnf7S6Mw24PncJyzbFosQRZfG440V3MotTel4H/HiW4cA/aACJnq+Nv4Ay4 qDfm3H264C2+gZDBRekSe/tsWErRJbz1awWxTNz2eGCf8xnfyyQX+wCXAjhyk5CQqga7 sEhAR6ukwRCWe2//4cH//Rw+1+6MqCwH3rqLRFMKuSfUZAKkjdU4zTctzvQ78+aR2vJV 9t4A== X-Gm-Message-State: AOAM532qIVo9oFT9tXADgKFLR3l6QdlfhVlIJ1Nd0uS3SbX0FVEoQLGr 8Cu/9HEbOEDfD+Wsd/3oVuXY4Fc= X-Google-Smtp-Source: ABdhPJzqIMV6Ry+GWZxYcVy/sQGCdQZUUzo9NL/oGx/nnIZPmjndtsOBV2xU/iju6AeRrIkb9GVGO28= X-Received: from sdf2.svl.corp.google.com ([2620:15c:2c4:201:a900:e0f6:cf98:d8c8]) (user=sdf job=sendgmr) by 2002:a25:9f0d:0:b0:634:37e:3b8c with SMTP id n13-20020a259f0d000000b00634037e3b8cmr25121216ybq.8.1648491416289; Mon, 28 Mar 2022 11:16:56 -0700 (PDT) Date: Mon, 28 Mar 2022 11:16:41 -0700 In-Reply-To: <20220328181644.1748789-1-sdf@google.com> Message-Id: <20220328181644.1748789-5-sdf@google.com> Mime-Version: 1.0 References: <20220328181644.1748789-1-sdf@google.com> X-Mailer: git-send-email 2.35.1.1021.g381101b075-goog Subject: [PATCH bpf-next 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 9cc2f0bf78f1..86e2ec2ce7fd 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; } -- 2.35.1.1021.g381101b075-goog