From patchwork Fri Mar 22 15:14:59 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Willem de Bruijn X-Patchwork-Id: 1061303 Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@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=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="u+L5YhId"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 44QnK64Kdzz9sRm for ; Sat, 23 Mar 2019 02:15:22 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727066AbfCVPPV (ORCPT ); Fri, 22 Mar 2019 11:15:21 -0400 Received: from mail-qt1-f193.google.com ([209.85.160.193]:40495 "EHLO mail-qt1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726995AbfCVPPT (ORCPT ); Fri, 22 Mar 2019 11:15:19 -0400 Received: by mail-qt1-f193.google.com with SMTP id x12so2882986qts.7 for ; Fri, 22 Mar 2019 08:15:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=SZUgT7jqjPKvxVPFpplaYzoTds3V8Vv05KAFBKPkgKk=; b=u+L5YhIdaXgMDHL3MLA26yiewRhKujdFF0Uk8hP0f4Dm4Xqp64wuxjm16MiifX1byC mi4zMbwFB+9gX2ZbcEYb6kGJCyXxFzHd0n7/nlxlp9mQEz0HhHKKimGdahgWd45qEqHG bfQS+m7fOTn3DIPFL+5Zter/2NPQ9M8FX5pYhW8X+at11Uis8UEe15gn/DTYEzm0gm6J 2BTruOEOATxA3LknOIsLsd3qEamhRnYZixngv/d46Rm4Des+nTsCbAbfCcQwjuMjSqMs ZwYNoWHkbgXaOWYJU6ziUOGJA6xltNoTGOhno+bTY8BEqqlgRprUsNP0xNXOkVX1d0iz uHfw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=SZUgT7jqjPKvxVPFpplaYzoTds3V8Vv05KAFBKPkgKk=; b=GYM+x3a8cfLdYxg+gEijySBHuGU5fQcMnN7d5teU08OfbdHv5rvMAN6NY+wAEyjhxD ReX/S13CHb8e2RSsKWfccKkJlfRPqrLOb9VRba7ahXGHL779Ho1dJNVVP5zyiKtbiWzi o7RwJnzwj5BnWPKb2pzMO1Thu8GEsShzCsrSyDQ0fm+6MOPvugDLpl9Dlh0/oTG89RKf XlfeUKuWRwr269T2abjnm7do5GyNqXOd4nVNX+4PZVSWIbihDReYMstbFs7e9zHxAjvJ NO5h1TaGNpW/nxYzpR00XFQayVp7EFQSNrmnhavXvwTEJLP910J0tADIi1dfdx+1rQY7 Zk6Q== X-Gm-Message-State: APjAAAX/fOYGX/hHGKpPrlA+9yGXoRVyeQlx52Dn42M6Pfnn8fa7FT2n b4UvTwrez3NNRlWQoJr+qCfqblOG X-Google-Smtp-Source: APXvYqy3WqVWdZc1xp7UZY7QpxgVA5kF97v6bSGc6LfzT0dS83c49DHAz2EId6xGcV+5Ul9MDu/zZw== X-Received: by 2002:ac8:3328:: with SMTP id t37mr8875141qta.246.1553267717879; Fri, 22 Mar 2019 08:15:17 -0700 (PDT) Received: from willemb1.nyc.corp.google.com ([2620:0:1003:315:3fa1:a34c:1128:1d39]) by smtp.gmail.com with ESMTPSA id v4sm4631317qtq.94.2019.03.22.08.15.16 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 22 Mar 2019 08:15:16 -0700 (PDT) From: Willem de Bruijn To: netdev@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, alan.maguire@oracle.com, Willem de Bruijn Subject: [PATCH bpf-next v2 08/13] bpf: add bpf_skb_adjust_room flag BPF_F_ADJ_ROOM_FIXED_GSO Date: Fri, 22 Mar 2019 11:14:59 -0400 Message-Id: <20190322151504.89983-9-willemdebruijn.kernel@gmail.com> X-Mailer: git-send-email 2.21.0.392.gf8f6787159e-goog In-Reply-To: <20190322151504.89983-1-willemdebruijn.kernel@gmail.com> References: <20190322151504.89983-1-willemdebruijn.kernel@gmail.com> MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Willem de Bruijn bpf_skb_adjust_room adjusts gso_size of gso packets to account for the pushed or popped header room. This is not allowed with UDP, where gso_size delineates datagrams. Add an option to avoid these updates and allow this call for datagrams. It can also be used with TCP, when MSS is known to allow headroom, e.g., through MSS clamping or route MTU. Changes v1->v2: - document flag BPF_F_ADJ_ROOM_FIXED_GSO - do not expose BPF_F_ADJ_ROOM_MASK through uapi, as it may change. Link: https://patchwork.ozlabs.org/patch/1052497/ Signed-off-by: Willem de Bruijn --- include/uapi/linux/bpf.h | 9 +++++++-- net/core/filter.c | 38 +++++++++++++++++++++++++++----------- 2 files changed, 34 insertions(+), 13 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 7c8fd0647070..4f157d0ec571 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1486,8 +1486,10 @@ union bpf_attr { * * **BPF_ADJ_ROOM_NET**: Adjust room at the network layer * (room space is added or removed below the layer 3 header). * - * All values for *flags* are reserved for future usage, and must - * be left at zero. + * There is one supported flag at this time: + * + * * **BPF_F_ADJ_ROOM_FIXED_GSO**: Do not adjust gso_size. + * Adjusting mss in this way is not allowed for datagrams. * * A call to this helper is susceptible to change the underlaying * packet buffer. Therefore, at load time, all checks on pointers @@ -2627,6 +2629,9 @@ enum bpf_func_id { /* Current network namespace */ #define BPF_F_CURRENT_NETNS (-1L) +/* BPF_FUNC_skb_adjust_room flags. */ +#define BPF_F_ADJ_ROOM_FIXED_GSO (1ULL << 0) + /* Mode for BPF_FUNC_skb_adjust_room helper. */ enum bpf_adj_room_mode { BPF_ADJ_ROOM_NET, diff --git a/net/core/filter.c b/net/core/filter.c index e7b7720b18e9..393d1e4903b5 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2963,12 +2963,17 @@ static u32 bpf_skb_net_base_len(const struct sk_buff *skb) } } -static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff) +static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff, + u64 flags) { int ret; - if (skb_is_gso(skb) && !skb_is_gso_tcp(skb)) - return -ENOTSUPP; + if (skb_is_gso(skb) && !skb_is_gso_tcp(skb)) { + /* udp gso_size delineates datagrams, only allow if fixed */ + if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4) || + !(flags & BPF_F_ADJ_ROOM_FIXED_GSO)) + return -ENOTSUPP; + } ret = skb_cow_head(skb, len_diff); if (unlikely(ret < 0)) @@ -2982,7 +2987,9 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff) struct skb_shared_info *shinfo = skb_shinfo(skb); /* Due to header grow, MSS needs to be downgraded. */ - skb_decrease_gso_size(shinfo, len_diff); + if (!(flags & BPF_F_ADJ_ROOM_FIXED_GSO)) + skb_decrease_gso_size(shinfo, len_diff); + /* Header must be checked, and gso_segs recomputed. */ shinfo->gso_type |= SKB_GSO_DODGY; shinfo->gso_segs = 0; @@ -2991,12 +2998,17 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff) return 0; } -static int bpf_skb_net_shrink(struct sk_buff *skb, u32 off, u32 len_diff) +static int bpf_skb_net_shrink(struct sk_buff *skb, u32 off, u32 len_diff, + u64 flags) { int ret; - if (skb_is_gso(skb) && !skb_is_gso_tcp(skb)) - return -ENOTSUPP; + if (skb_is_gso(skb) && !skb_is_gso_tcp(skb)) { + /* udp gso_size delineates datagrams, only allow if fixed */ + if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4) || + !(flags & BPF_F_ADJ_ROOM_FIXED_GSO)) + return -ENOTSUPP; + } ret = skb_unclone(skb, GFP_ATOMIC); if (unlikely(ret < 0)) @@ -3010,7 +3022,9 @@ static int bpf_skb_net_shrink(struct sk_buff *skb, u32 off, u32 len_diff) struct skb_shared_info *shinfo = skb_shinfo(skb); /* Due to header shrink, MSS can be upgraded. */ - skb_increase_gso_size(shinfo, len_diff); + if (!(flags & BPF_F_ADJ_ROOM_FIXED_GSO)) + skb_increase_gso_size(shinfo, len_diff); + /* Header must be checked, and gso_segs recomputed. */ shinfo->gso_type |= SKB_GSO_DODGY; shinfo->gso_segs = 0; @@ -3025,6 +3039,8 @@ static u32 __bpf_skb_max_len(const struct sk_buff *skb) SKB_MAX_ALLOC; } +#define BPF_F_ADJ_ROOM_MASK (BPF_F_ADJ_ROOM_FIXED_GSO) + BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff, u32, mode, u64, flags) { @@ -3037,7 +3053,7 @@ BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff, u32 off; int ret; - if (unlikely(flags)) + if (unlikely(flags & ~BPF_F_ADJ_ROOM_MASK)) return -EINVAL; if (unlikely(len_diff_abs > 0xfffU)) return -EFAULT; @@ -3065,8 +3081,8 @@ BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff, !skb_is_gso(skb)))) return -ENOTSUPP; - ret = shrink ? bpf_skb_net_shrink(skb, off, len_diff_abs) : - bpf_skb_net_grow(skb, off, len_diff_abs); + ret = shrink ? bpf_skb_net_shrink(skb, off, len_diff_abs, flags) : + bpf_skb_net_grow(skb, off, len_diff_abs, flags); bpf_compute_data_pointers(skb); return ret;