From patchwork Wed Mar 25 17:23:26 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= X-Patchwork-Id: 1261556 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 (no SPF record) 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=none dis=none) header.from=redhat.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=hvkQ3XF0; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 48nZhk6R41z9sPk for ; Thu, 26 Mar 2020 04:23:34 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727685AbgCYRXd (ORCPT ); Wed, 25 Mar 2020 13:23:33 -0400 Received: from us-smtp-delivery-74.mimecast.com ([63.128.21.74]:51583 "EHLO us-smtp-delivery-74.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727574AbgCYRXd (ORCPT ); Wed, 25 Mar 2020 13:23:33 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585157011; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=k5hr2aQZeEb8hZ8qYomsvDOaw9krebjQTQ3Tidf7gec=; b=hvkQ3XF0gB7HvSXQpgQZQQv0YmkxU2gYvh2tJjVJjx56PB/bAt1RVCHXG96zApx7LU9vAt JqbdlcXoyoZYwctCEh3w6N+lcbexMsXIsRAOXPXQETzE4NY/bSPmOBntuO+OA5jkBTZuZA +nfkkMdofN71XmwFyyZ8a7iStDSTWkE= Received: from mail-lf1-f69.google.com (mail-lf1-f69.google.com [209.85.167.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-116-t6NJ2HY2NjG5m6ehcak2Ng-1; Wed, 25 Mar 2020 13:23:29 -0400 X-MC-Unique: t6NJ2HY2NjG5m6ehcak2Ng-1 Received: by mail-lf1-f69.google.com with SMTP id 144so1116875lfj.1 for ; Wed, 25 Mar 2020 10:23:29 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:date:message-id:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=k5hr2aQZeEb8hZ8qYomsvDOaw9krebjQTQ3Tidf7gec=; b=AkEXDYNKFuobmFQF5cssHmFrj4WJGItrQYG80YM+sbLFyOvSZsjN9IUERktKLtzXeC vVMf5159UF/GedLQN7BIeX/jFSewBBFdS+8R1rq14Vzk0joitJJsUFpiAckmGrhp2XRa SoA/A1GYvSM0bLulRkmAJElRrymIM4TLva+oc1OsVD9SY6MrvZ7dV5GPv1wg6q2eV5Lc 92xFFxiIDFYgJ/Sfd4Xg+im6o9+/Uj4DRUbx4RW7W1s/AAb55YRZXoQfeLAOwr/iFUVL vDThIYV74vaLD9mQ7+CvcV7fBB3knNHtvPnyqRSVNuYJcYCFAZxA/bKfmD+gqxEU20l/ CC0Q== X-Gm-Message-State: ANhLgQ3T/Tml8JoqEXcyi5zkpE3Z0K7H9o9qvk6p+MFMNmMWGqEWClGg M4fQ8K6F/VPt7AMsDg6FXqpUVZWmhv9rk+bJL31jYV3JFqX7Fx0ftB1ABkBCcdAAEeqSZQb0nAN 409slbUUeadm/ X-Received: by 2002:ac2:4309:: with SMTP id l9mr2949728lfh.65.1585157007977; Wed, 25 Mar 2020 10:23:27 -0700 (PDT) X-Google-Smtp-Source: ADFU+vvw94eQR7JpRbshHnHYbaZ3gUDI6xS3iCk74YM8ZCWpwuGcETt3HjsTv47oTnIA5Vo5fzRPzQ== X-Received: by 2002:ac2:4309:: with SMTP id l9mr2949714lfh.65.1585157007734; Wed, 25 Mar 2020 10:23:27 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk ([2a0c:4d80:42:443::2]) by smtp.gmail.com with ESMTPSA id m21sm12313936ljb.89.2020.03.25.10.23.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Mar 2020 10:23:27 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 72D0018158C; Wed, 25 Mar 2020 18:23:26 +0100 (CET) Subject: [PATCH bpf-next v4 1/4] xdp: Support specifying expected existing program when attaching XDP From: =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= To: netdev@vger.kernel.org Cc: bpf@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , "David S. Miller" , Jakub Kicinski , Jesper Dangaard Brouer , John Fastabend , Lorenz Bauer , Andrey Ignatov Date: Wed, 25 Mar 2020 18:23:26 +0100 Message-ID: <158515700640.92963.3551295145441017022.stgit@toke.dk> In-Reply-To: <158515700529.92963.17609642163080084530.stgit@toke.dk> References: <158515700529.92963.17609642163080084530.stgit@toke.dk> User-Agent: StGit/0.22 MIME-Version: 1.0 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org From: Toke Høiland-Jørgensen While it is currently possible for userspace to specify that an existing XDP program should not be replaced when attaching to an interface, there is no mechanism to safely replace a specific XDP program with another. This patch adds a new netlink attribute, IFLA_XDP_EXPECTED_FD, which can be set along with IFLA_XDP_FD. If set, the kernel will check that the program currently loaded on the interface matches the expected one, and fail the operation if it does not. This corresponds to a 'cmpxchg' memory operation. Setting the new attribute with a negative value means that no program is expected to be attached, which corresponds to setting the UPDATE_IF_NOEXIST flag. A new companion flag, XDP_FLAGS_REPLACE, is also added to explicitly request checking of the EXPECTED_FD attribute. This is needed for userspace to discover whether the kernel supports the new attribute. Reviewed-by: Jakub Kicinski Signed-off-by: Toke Høiland-Jørgensen --- include/linux/netdevice.h | 2 +- include/uapi/linux/if_link.h | 4 +++- net/core/dev.c | 26 +++++++++++++++++++++----- net/core/rtnetlink.c | 14 ++++++++++++++ 4 files changed, 39 insertions(+), 7 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 654808bfad83..b503d468f0df 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -3768,7 +3768,7 @@ struct sk_buff *dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev, typedef int (*bpf_op_t)(struct net_device *dev, struct netdev_bpf *bpf); int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack, - int fd, u32 flags); + int fd, int expected_fd, u32 flags); u32 __dev_xdp_query(struct net_device *dev, bpf_op_t xdp_op, enum bpf_netdev_command cmd); int xdp_umem_query(struct net_device *dev, u16 queue_id); diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h index 61e0801c82df..c2f768c8d65b 100644 --- a/include/uapi/linux/if_link.h +++ b/include/uapi/linux/if_link.h @@ -972,11 +972,12 @@ enum { #define XDP_FLAGS_SKB_MODE (1U << 1) #define XDP_FLAGS_DRV_MODE (1U << 2) #define XDP_FLAGS_HW_MODE (1U << 3) +#define XDP_FLAGS_REPLACE (1U << 4) #define XDP_FLAGS_MODES (XDP_FLAGS_SKB_MODE | \ XDP_FLAGS_DRV_MODE | \ XDP_FLAGS_HW_MODE) #define XDP_FLAGS_MASK (XDP_FLAGS_UPDATE_IF_NOEXIST | \ - XDP_FLAGS_MODES) + XDP_FLAGS_MODES | XDP_FLAGS_REPLACE) /* These are stored into IFLA_XDP_ATTACHED on dump. */ enum { @@ -996,6 +997,7 @@ enum { IFLA_XDP_DRV_PROG_ID, IFLA_XDP_SKB_PROG_ID, IFLA_XDP_HW_PROG_ID, + IFLA_XDP_EXPECTED_FD, __IFLA_XDP_MAX, }; diff --git a/net/core/dev.c b/net/core/dev.c index d84541c24446..651a3c28d33a 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -8655,15 +8655,17 @@ static void dev_xdp_uninstall(struct net_device *dev) * @dev: device * @extack: netlink extended ack * @fd: new program fd or negative value to clear + * @expected_fd: old program fd that userspace expects to replace or clear * @flags: xdp-related flags * * Set or clear a bpf program for a device */ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack, - int fd, u32 flags) + int fd, int expected_fd, u32 flags) { const struct net_device_ops *ops = dev->netdev_ops; enum bpf_netdev_command query; + u32 prog_id, expected_id = 0; struct bpf_prog *prog = NULL; bpf_op_t bpf_op, bpf_chk; bool offload; @@ -8684,15 +8686,29 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack, if (bpf_op == bpf_chk) bpf_chk = generic_xdp_install; - if (fd >= 0) { - u32 prog_id; + prog_id = __dev_xdp_query(dev, bpf_op, query); + if (flags & XDP_FLAGS_REPLACE) { + if (expected_fd >= 0) { + prog = bpf_prog_get_type_dev(expected_fd, + BPF_PROG_TYPE_XDP, + bpf_op == ops->ndo_bpf); + if (IS_ERR(prog)) + return PTR_ERR(prog); + expected_id = prog->aux->id; + bpf_prog_put(prog); + } + if (prog_id != expected_id) { + NL_SET_ERR_MSG(extack, "Active program does not match expected"); + return -EEXIST; + } + } + if (fd >= 0) { if (!offload && __dev_xdp_query(dev, bpf_chk, XDP_QUERY_PROG)) { NL_SET_ERR_MSG(extack, "native and generic XDP can't be active at the same time"); return -EEXIST; } - prog_id = __dev_xdp_query(dev, bpf_op, query); if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) && prog_id) { NL_SET_ERR_MSG(extack, "XDP program already attached"); return -EBUSY; @@ -8715,7 +8731,7 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack, return 0; } } else { - if (!__dev_xdp_query(dev, bpf_op, query)) + if (!prog_id) return 0; } diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 14e6ea21c378..709ebbf8ab5b 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -1872,7 +1872,9 @@ static const struct nla_policy ifla_port_policy[IFLA_PORT_MAX+1] = { }; static const struct nla_policy ifla_xdp_policy[IFLA_XDP_MAX + 1] = { + [IFLA_XDP_UNSPEC] = { .strict_start_type = IFLA_XDP_EXPECTED_FD }, [IFLA_XDP_FD] = { .type = NLA_S32 }, + [IFLA_XDP_EXPECTED_FD] = { .type = NLA_S32 }, [IFLA_XDP_ATTACHED] = { .type = NLA_U8 }, [IFLA_XDP_FLAGS] = { .type = NLA_U32 }, [IFLA_XDP_PROG_ID] = { .type = NLA_U32 }, @@ -2799,8 +2801,20 @@ static int do_setlink(const struct sk_buff *skb, } if (xdp[IFLA_XDP_FD]) { + int expected_fd = -1; + + if (xdp_flags & XDP_FLAGS_REPLACE) { + if (!xdp[IFLA_XDP_EXPECTED_FD]) { + err = -EINVAL; + goto errout; + } + expected_fd = + nla_get_s32(xdp[IFLA_XDP_EXPECTED_FD]); + } + err = dev_change_xdp_fd(dev, extack, nla_get_s32(xdp[IFLA_XDP_FD]), + expected_fd, xdp_flags); if (err) goto errout;