From patchwork Mon Apr 1 20:57:33 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stanislav Fomichev X-Patchwork-Id: 1073241 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=bpf-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.b="EMQCLgQD"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 44Y4Rc4dcdz9sSK for ; Tue, 2 Apr 2019 07:57:48 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726924AbfDAU5s (ORCPT ); Mon, 1 Apr 2019 16:57:48 -0400 Received: from mail-io1-f74.google.com ([209.85.166.74]:46051 "EHLO mail-io1-f74.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728551AbfDAU5r (ORCPT ); Mon, 1 Apr 2019 16:57:47 -0400 Received: by mail-io1-f74.google.com with SMTP id r21so9096266iod.12 for ; Mon, 01 Apr 2019 13:57:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=vNIYa8Lob8GaCf02abW7dYTE9zt9QRXGalzndleWpZA=; b=EMQCLgQDuQTAzGxVEy19Fng5ugj3v7m37tmEY6bvRSt9o83AbNiERl4vKuNs3eUh4M mie5mXt4/l/t+mTl9rm0N2271oh+8thQkKlsNtSt//RdRrdTPPOdHqfdOFcYfOmO/Et9 eGBaxMuUZMMj/0RuqHfjstTl4k+riFBaXN5UE/xjpUBwuX38ryL3u6dUFuq7n2DO2+qv 196GPlOc6JvaF5SQOT+wUp9kvZWcUjhg+fSze//9ZPMoB6lb72ZTGIPMyaTiE8kYuk2k cd7JYfczEzYSwtFna/ofOw54FFNEojOXlG8IG16q4DNz8mzJExqMaWm/eJ41q/TC7w4n dICQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=vNIYa8Lob8GaCf02abW7dYTE9zt9QRXGalzndleWpZA=; b=KMp9QlwnDFh+Hu59K6i84pHhRUEznOzJUuVwMiErkFPYANZYyjk9GG8gr5fom7i5lV UWCtpz10qBKV1i1w2P7uOUnulslmpAaLWokscCg6EguQfEzOzZpGl3uEKVH3iXKcva4/ X79OaekW/YGnbekGEliHl7Hwmys57lJ1dMaGImqt5XF/SQ3tNszbZ4otT1n8oJOACyBg v0WTb45hxRKSkgq8BHOcObkh0Kd/Sy8+n2Uk9ywz57zjqkRO+fIJO86L1Y1UP69+fEkp dqn0TNCNgv/getPsEbck0WedqyOH039KXFtNK1CRO7ltiwPhVtGYecGv7iIxkpEKTOOz QKyQ== X-Gm-Message-State: APjAAAVvkcsytDDgAKFOJxHSCVE0Lo5eYYYhPeVDjz1K45k9+cpZhhJG oRkCW76HHv1E55JL+izBFlGnnpA= X-Google-Smtp-Source: APXvYqwFTeO6Cqilra7ujGMHast//X8d5iHsRbhdDVJn+wzOKGpSotypRN7vxhibxq97hoqkFPZsWBg= X-Received: by 2002:a24:764b:: with SMTP id z72mr7401300itb.22.1554152266677; Mon, 01 Apr 2019 13:57:46 -0700 (PDT) Date: Mon, 1 Apr 2019 13:57:33 -0700 In-Reply-To: <20190401205734.4400-1-sdf@google.com> Message-Id: <20190401205734.4400-5-sdf@google.com> Mime-Version: 1.0 References: <20190401205734.4400-1-sdf@google.com> X-Mailer: git-send-email 2.21.0.392.gf8f6787159e-goog Subject: [PATCH bpf 4/5] flow_dissector: allow access only to a subset of __sk_buff fields From: Stanislav Fomichev To: netdev@vger.kernel.org, bpf@vger.kernel.org Cc: davem@davemloft.net, ast@kernel.org, daniel@iogearbox.net, simon.horman@netronome.com, willemb@google.com, peterpenkov96@gmail.com, Stanislav Fomichev Sender: bpf-owner@vger.kernel.org Precedence: bulk List-Id: netdev.vger.kernel.org Use whitelist instead of a blacklist and allow only a small set of fields that might be relevant in the context of flow dissector: * data * data_end * flow_keys This is required for the eth_get_headlen case where we have only a chunk of data to dissect (i.e. trying to read the other skb fields doesn't make sense). Note, that it is a breaking API change! However, we've provided flow_keys->n_proto as a substitute for skb->protocol; and there is no need to manually handle skb->vlan_present. So even if we break somebody, the migration is trivial. Unfortunately, we can't support eth_get_headlen use-case without those breaking changes. Signed-off-by: Stanislav Fomichev --- net/core/filter.c | 16 +++------------- 1 file changed, 3 insertions(+), 13 deletions(-) diff --git a/net/core/filter.c b/net/core/filter.c index 647c63a7b25b..fc92ebc4e200 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -6613,14 +6613,8 @@ static bool flow_dissector_is_valid_access(int off, int size, const struct bpf_prog *prog, struct bpf_insn_access_aux *info) { - if (type == BPF_WRITE) { - switch (off) { - case bpf_ctx_range_till(struct __sk_buff, cb[0], cb[4]): - break; - default: - return false; - } - } + if (type == BPF_WRITE) + return false; switch (off) { case bpf_ctx_range(struct __sk_buff, data): @@ -6632,11 +6626,7 @@ static bool flow_dissector_is_valid_access(int off, int size, case bpf_ctx_range_ptr(struct __sk_buff, flow_keys): info->reg_type = PTR_TO_FLOW_KEYS; break; - case bpf_ctx_range(struct __sk_buff, tc_classid): - case bpf_ctx_range(struct __sk_buff, data_meta): - case bpf_ctx_range_till(struct __sk_buff, family, local_port): - case bpf_ctx_range(struct __sk_buff, tstamp): - case bpf_ctx_range(struct __sk_buff, wire_len): + default: return false; }