From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.85.214.198 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793989213; b=Ejy29pAUH4e3afTgxvUwIFDXxkfgzylsb8OlS3jqLsuLhDK4p1EGI5PiYN+jBFGXIwzL 7LTZOcN4SRphaz3Ui9jl6gYeOMf8jr7RwdBwMTpQ/R1cHXnd0OoGsSSgBpcXVbJUBcD1H wMpdjNl89MgyK8mAmSafIbftfxTGrG1d1z9djRDU7qO7F4pptssB4jvdQ3htAAE8OqblL EJnu81p7BwP/WDWDbklZ1u0Tcz+igdOt2uj5o1Bl9YIzXBr0T6jRQ+b7Z3nwKldPBlRqb 97h+mWuE2VPPjjyJKfcJUAXOFyY+jaa0V1DxursgixhK6dTWKEtmvrFBRd6uc9vloAA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793989213; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Received:Date:In-Reply-To: Mime-Version:References:X-Mailer:Message-ID:Subject:From:To:Cc: Content-Type; bh=vVMMjsoejtuZj+6jaOVjoI+Z/1D0Mv2jKvwK7taNrxA=; b=r1cv5VwKyFGIHHynOmeenJjdszxYu6m5aPtoFvSIMCs1gpfREAC9uOgg3bwWqxouZ883 wsAtRmm86R8doSXgJa6i8zuXPEh/xV/v07iBhlJR2CIh2zo0FhtL7OodTiV61klNayqN+ b+RU7ykWwsmelKlG5CXjs1ca0DaVuFBpraLPx9QEEa6Ys8s1OKS1tMUj0FE5bLya/Oy7g vS/nFtSe0KJa4F+GATANbP9jaGzbGyXFeK1eelokZFcvvTEhxeTaSQpiu9Oj+C60C4agZ yu65bg6laSKQ3QmlqkN+Dv4OITlr921gbJKexzZBudrr4rFMrtCH4ZGPy/OHgombskQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=google.com; spf=pass smtp.mailfrom=flex--weiwan.bounces.google.com; dkim=pass header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20260707 header.b=M77jK3Gd; arc=none smtp.remote-ip=209.85.214.198 Received: from mail-pl1-f198.google.com (mail-pl1-f198.google.com [209.85.214.198]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9D300606A337 for ; Fri, 6 Nov 2026 18:20:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 9D300606A337 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--weiwan.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20260707 header.b=M77jK3Gd Received: by mail-pl1-f198.google.com with SMTP id d9443c01a7336-2ed34e33913so5562145ad.0 for ; Fri, 06 Nov 2026 10:20:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20260707; t=1793989212; x=1794594012; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=vVMMjsoejtuZj+6jaOVjoI+Z/1D0Mv2jKvwK7taNrxA=; b=M77jK3GdF10MK0SFm6xKbtL4I00S0TgdZ1/xKISKVEwsLGZwbFJ5bkE2ZalS2qQ+HZ e/gRLQ+TmqQtBTZ0nZkGwRkfBPJcDoulaP6hf1G0DgprojSww+q87VTESrOXgN9oMJqz 9S2bO4fxfoXa5ZYXnfnby+Runhw1YLjcmb/ssfDdRHSuVztt/GupfikH681rI4O5JMVf uCLqpC2RUcmtYHzdtuI1Kc+UaOBbJJOTOH5XQr+Y1Ccr4AlB6oV0YlEVxDRACnCycsz2 wLThmIvFat6LnreBgVQ07hlVMVodSdAKEMskqAPxFztARFTEVSTaueF+TfUN6Q0epKnu tx2g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1793989212; x=1794594012; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=vVMMjsoejtuZj+6jaOVjoI+Z/1D0Mv2jKvwK7taNrxA=; b=TH7sLCxifDL1gT+D86Sx6PZbbaXgePy+wQYLeJriF7KXaGMtiEOvyOU6R8kW0dKw7P jqpNxJxVBhwkNoh+EoQKByNFyTJnYFivd5VJixQUaYupo9EvGyy5uevzqGrF7mWmNIyV AeqfcL7oH4O+Vu6YddlBCYBZcimRS+48dkNNYXKjElk+KzsPHGmQAwzIg4nXUUpR3xoV SgBY4IK3H63xP+E1ghtrEriCGWau5+AGR6EDA0HG/j128UjCNgQnYSWIxudDZwcfOR6r uq/kkaZfylXzv38H0DDAYIbVYQ0eF9FNz6S+y6sSZjmnOVHGspwXeSTQAEkLOIA6gTEM QUNw== X-Forwarded-Encrypted: i=1; AL+hErECZ4lT0kh5MVHUk7AJxaw9udjWq6SgBD53ekeKMyprSk3GHSPRz/9ZHpXX86KZzcfV3PM=@vger.kernel.org X-Gm-Message-State: APuU4Z/cAA8wdDtBQU8T6H4Oex0oUOdyFq/yLgRQxpeFOcffwwrbgzf0 QYk6ZP89mGiE6pJenuaMu0kSp/M+Zdt6g90VSAE7CaMfkwHHWspahj9ajNCsWkjxfulf6LtW7WO ec8XSTA== X-Received: from pjqq12.prod.google.com ([2002:a17:90b:584c:b0:3ae:825a:57e3]) (user=weiwan job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:3ec8:b0:3ac:ad90:7090 with SMTP id 98e67ed59e1d1-3b0db72df0fmr3414472a91.67.1793989211751; Fri, 06 Nov 2026 10:20:11 -0800 (PST) Date: Fri, 6 Nov 2026 18:20:06 +0000 In-Reply-To: <20261106182007.374660-1-weiwan@google.com> X-Mailing-List: bpf@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list Mime-Version: 1.0 References: <20261106182007.374660-1-weiwan@google.com> X-Mailer: git-send-email 2.56.0.455.g6c5a503b38-goog Message-ID: <20261106182007.374660-2-weiwan@google.com> Subject: [PATCH net v3 1/2] net: Make PSP skb extension survive packet scrubbing From: Wei Wang To: "David S . Miller" , Jakub Kicinski , Paolo Abeni , Andrew Lunn , Shuah Khan Cc: Simon Horman , Jakub Sitnicki , Daniel Zahka , Willem de Bruijn , netdev@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, Wei Wang Content-Type: text/plain; charset="UTF-8" skb_scrub_packet() drops all skb extensions unconditionally via skb_ext_reset(). It runs on tunnel encap/decap (ip_tunnel_rcv, vxlan_rcv, etc.) and virtual device forwarding/redirection (dev_forward_skb, netkit_xmit, skb_do_redirect). When a virtual device such as netkit is associated with a PSP device in another network namespace via PSP_CMD_DEV_ASSOC, incoming PSP packets decapsulated by psp_dev_rcv() lose their SKB_EXT_PSP extension when scrubbed during redirection into the peer netns. Without SKB_EXT_PSP, __psp_sk_rx_policy_check() rejects incoming TCP data segments at the socket layer with SKB_DROP_REASON_PSP_INPUT. Introduce a static skb_ext_scrub() helper in net/core/skbuff.c to preserve SKB_EXT_PSP across skb_scrub_packet() while dropping all other extensions. If SKB_EXT_PSP is not active, skb_ext_scrub() simply calls skb_ext_reset(). If SKB_EXT_PSP is the only extension in the skb_ext buffer, nothing needs to be scrubbed. Otherwise, save the PSP metadata, reset the extension block, and re-add a fresh SKB_EXT_PSP extension. Fixes: 06c2dce2d0f6 ("psp: add new netlink cmd for dev-assoc and dev-disassoc") Link: https://lore.kernel.org/r/20260910-bpf-meta-inside-skb-ext-v2-3-0b21e42180b0@cloudflare.com Reported-by: Daniel Zahka Closes: https://lore.kernel.org/netdev/DLODSKPY6ON6.1G6SP3CFFLCPJ@gmail.com/ Co-developed-by: Jakub Sitnicki Signed-off-by: Jakub Sitnicki Signed-off-by: Wei Wang Reviewed-by: Daniel Zahka --- net/core/skbuff.c | 30 ++++++++++++++++++++++++++++-- 1 file changed, 28 insertions(+), 2 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 93c2f440b9ec..ddbf0f3342ca 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -6369,6 +6369,31 @@ bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from, } EXPORT_SYMBOL(skb_try_coalesce); +static void skb_ext_scrub(struct sk_buff *skb) +{ +#if IS_ENABLED(CONFIG_INET_PSP) + struct psp_skb_ext *pse = skb_ext_find(skb, SKB_EXT_PSP); + + if (pse) { + struct skb_ext *ext = skb->extensions; + struct psp_skb_ext tmp; + + /* Nothing else to scrub if PSP is the only extension in ext. */ + if (ext->chunks == SKB_EXT_CHUNKSIZEOF(*ext) + + skb_ext_type_len[SKB_EXT_PSP]) + return; + + tmp = *pse; + skb_ext_reset(skb); + pse = skb_ext_add(skb, SKB_EXT_PSP); + if (pse) + memcpy(pse, &tmp, sizeof(*pse)); + return; + } +#endif + skb_ext_reset(skb); +} + /** * skb_scrub_packet - scrub an skb * @@ -6380,7 +6405,8 @@ EXPORT_SYMBOL(skb_try_coalesce); * operations. * skb_scrub_packet can also be used to clean a skb before injecting it in * another namespace (@xnet == true). We have to clear all information in the - * skb that could impact namespace isolation. + * skb that could impact namespace isolation. Note that PSP skb extension is + * preserved across packet scrubbing by design. */ void skb_scrub_packet(struct sk_buff *skb, bool xnet) { @@ -6388,7 +6414,7 @@ void skb_scrub_packet(struct sk_buff *skb, bool xnet) skb->skb_iif = 0; skb->ignore_df = 0; skb_dst_drop(skb); - skb_ext_reset(skb); + skb_ext_scrub(skb); nf_reset_ct(skb); nf_reset_trace(skb); -- 2.56.0.455.g6c5a503b38-goog