From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.20]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F1701389E02; Mon, 23 Mar 2026 19:25:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.20 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774293923; cv=none; b=P34bSfuBRTbuWXv6FD97fr3jdadc/47aYlObWqdNmhi16pOUNEPlqeGV7YqeJ7mb30AmbAZvG1sqj5+6Fn0hGqgmauVhPQC3znbCOEQEU4I8qeMTdwcU7B9sk5DeXyA6VOnpc+NQ1GkQ5Pg8RxlSkDf8N+90Uuifk9ic0Rnl9ec= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774293923; c=relaxed/simple; bh=wSK36BLO6NAprF4IEENsWONz2D/IodmGv6KzobcKq8k=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=jYvITrFjAjV0syERn6KEyGYgas5WcQtfYjxgVLPe+il08KyFIBDRaBjXsrAKdU7H+U/wtH8G7LPYy91/Z/6IXvOwHyn8B7LPCfYAufj4DcQbt30hIojzV9jMkCXbrQ0uoq7deI1cHvluHiLi9+1/52uPII/zKlrcCUfH6+WGlwE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=PmZgajHm; arc=none smtp.client-ip=198.175.65.20 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="PmZgajHm" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1774293923; x=1805829923; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=wSK36BLO6NAprF4IEENsWONz2D/IodmGv6KzobcKq8k=; b=PmZgajHm0nqJTlqqfoe6xru9h2xaY+KmBpVzRIxOUGQ0gD2Bx2Awhxmr znsnrAGoBdH50q4Xpy45migkQq2nfBeJ2S9d9iU22k3n77q+lamcjPOAJ SliPXDe7+We1mOEzSs2HbmWMLJxO9u977UDav4gfPtVBz0asunepRtgZi r7C63s0Ete0DKpZy2Jnw7Izq6Oo65d+8FJYx6Da6QuLeC8SlaaGghPIcE rvkv2Wd46sUf9YnSYjrKIbGaoXFa+VgtMkpJaeHn16wY7q5vwReJF4NV/ mcDz78I96wZGWm5g95NOXxWHV6+Bp+PD7q7KmKrVndapiavdVYeuttp+k g==; X-CSE-ConnectionGUID: ktInfWlTR0SvD28weiEcfw== X-CSE-MsgGUID: JOwcL/MmR2Wdn/mqVmX70w== X-IronPort-AV: E=McAfee;i="6800,10657,11738"; a="75013334" X-IronPort-AV: E=Sophos;i="6.23,137,1770624000"; d="scan'208";a="75013334" Received: from orviesa003.jf.intel.com ([10.64.159.143]) by orvoesa112.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Mar 2026 12:25:22 -0700 X-CSE-ConnectionGUID: /5x4hIGBTHi9iRXyUfcCtA== X-CSE-MsgGUID: L09FThPHQHqJ2Q+YEi41+A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.23,137,1770624000"; d="scan'208";a="228187900" Received: from boxer.igk.intel.com ([10.102.20.173]) by orviesa003.jf.intel.com with ESMTP; 23 Mar 2026 12:25:19 -0700 From: Maciej Fijalkowski To: netdev@vger.kernel.org Cc: bpf@vger.kernel.org, magnus.karlsson@intel.com, stfomichev@gmail.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, larysa.zaremba@intel.com, aleksander.lobakin@intel.com, bjorn@kernel.org, Maciej Fijalkowski Subject: [PATCH v3 net 4/8] xsk: validate MTU against usable frame size on bind Date: Mon, 23 Mar 2026 20:24:53 +0100 Message-Id: <20260323192457.504631-5-maciej.fijalkowski@intel.com> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20260323192457.504631-1-maciej.fijalkowski@intel.com> References: <20260323192457.504631-1-maciej.fijalkowski@intel.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit AF_XDP bind currently accepts zero-copy pool configurations without verifying that the device MTU fits into the usable frame space provided by the UMEM chunk. This becomes a problem since we started to respect tailroom which is subtracted from chunk_size (among with headroom). 2k chunk size might not provide enough space for standard 1500 MTU, so let us catch such settings at bind time. This prevents creating an already-invalid setup and complements the MTU change restriction for devices with an attached XSK pool. Signed-off-by: Maciej Fijalkowski --- net/xdp/xsk_buff_pool.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c index 729602a3cec0..b2b4158358b2 100644 --- a/net/xdp/xsk_buff_pool.c +++ b/net/xdp/xsk_buff_pool.c @@ -10,6 +10,8 @@ #include "xdp_umem.h" #include "xsk.h" +#define ETH_PAD_LEN (ETH_HLEN + 2 * VLAN_HLEN + ETH_FCS_LEN) + void xp_add_xsk(struct xsk_buff_pool *pool, struct xdp_sock *xs) { if (!xs->tx) @@ -157,6 +159,7 @@ static void xp_disable_drv_zc(struct xsk_buff_pool *pool) int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *netdev, u16 queue_id, u16 flags) { + bool mbuf = flags & XDP_USE_SG; bool force_zc, force_copy; struct netdev_bpf bpf; int err = 0; @@ -178,7 +181,7 @@ int xp_assign_dev(struct xsk_buff_pool *pool, if (err) return err; - if (flags & XDP_USE_SG) + if (mbuf) pool->umem->flags |= XDP_UMEM_SG_FLAG; if (flags & XDP_USE_NEED_WAKEUP) @@ -200,10 +203,17 @@ int xp_assign_dev(struct xsk_buff_pool *pool, goto err_unreg_pool; } - if (netdev->xdp_zc_max_segs == 1 && (flags & XDP_USE_SG)) { + if (netdev->xdp_zc_max_segs == 1 && mbuf) { err = -EOPNOTSUPP; goto err_unreg_pool; } + if (!mbuf) { + if (netdev->mtu + ETH_PAD_LEN > + xsk_pool_get_rx_frame_size(pool)) { + err = -EINVAL; + goto err_unreg_pool; + } + } if (dev_get_min_mp_channel_count(netdev)) { err = -EBUSY; -- 2.43.0