From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pz2-f40.google.com (mail-pz2-f40.google.com [74.125.228.40]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CF61A4C6537 for ; Mon, 21 Sep 2026 17:39:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.228.40 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790012388; cv=none; b=K6KGP1q8vrOmXwXPHB0lpfpxTBInW9VygBPB7UwDJ6FiuRBtLxP8IT7svkcOSh9GVcEhhH/u+HbGGIpo86owwERZzn7XmRNgDmuFDP/jUQSGyCuRmmh4PA0qM3CE/h5//H8uLedD+ifyhypYVZUUsQ0Wud4NVhwb41bBLjSUjI4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790012388; c=relaxed/simple; bh=U5EKdWBIbiSJU1dP09Omb4q7Mq8wk1havQycrFwGi+s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=N/vV9kD2Y8j1TTJnIhgXfG79pjIwhFrzBHa6YMDE7mV17Q1b0tSv44rStL7WgzVZuK3IrYDi+jOdXyxlZKHbf+KXfGMxq+v0/E/JnOUtWqKjC4q3s8INUQS0tmB0SAMewtlc8u/r/qq1/RTQ8Yb2w8xmGGEEYqmF6F75HJJQIfw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=jXTAaKPs; arc=none smtp.client-ip=74.125.228.40 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="jXTAaKPs" Received: by mail-pz2-f40.google.com with SMTP id 41be03b00d2f7-cc750a1482fso262141a12.2 for ; Mon, 21 Sep 2026 10:39:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1790012386; x=1790617186; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=w5FIqOvJ37TsMdMZxbiL8+8z7eHOaHEabZWsoVStaOQ=; b=jXTAaKPs74N5povwGroOLXHnRCwicKLScjR/cOolkBqb0m1nMJUoAhXmrw/kUfxa8q tEj+K80ADjNfAiv/6Yu/CO9K3RsiMflhgwZyy5iw0eQmxQBlKISNecdxLJdc2Rx8yW8c 86xKSWxWw37D0bOiMWTBqBWz+HedZZWEZBfxntJAzHmwKpMjJ10uKAXGsMxWrN5ISctA nWW/GxMrlv9OsBAnBqliBj6HrwDtFfU9VnaIS59SIb0soR2lseF+wap1lDdjyuqWEBWa Te45lDBiTH+veIaFvwaWEdI5Dr15KUqsedSC/q7laSnBcO2gs+vXnH3f72NF5SDdshgO t32Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790012386; x=1790617186; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=w5FIqOvJ37TsMdMZxbiL8+8z7eHOaHEabZWsoVStaOQ=; b=ByvpEQilbl7uP+6n0K+BVe00dujWWFS8R0WW2WKdbiFlnJzJOZK2s8tVct56TeUkcf EgXFQfzzGurD6Cb/NbK0O3sVK+7XuwD/FCXWe1Blgr6Ak8WPumC3zjl0nX/nmNOuVIOj YSWWJuOdd85WggIXKAwgvVF5VVGEhL/sVblv/NwBc58DnEVmRUNasQYrtJvuWOoli3Vn 4W9lj3vlBYJ3iHO1R56iSEWu4rysJUugOrBZG5u7v25w1yvGhzeMBMyYsw0hzGNTZlZX lkRzBiePL+jnb5mFVy5d6baJZN9P9EMLf63bw7ux/uOMCmbqPZYOECxGrDA+0pM90xyf UTkQ== X-Forwarded-Encrypted: i=1; AKwUvBwUtmN9oENB4TSxvVEuOp0yivoX+mGLC9HDMoMmDBD7MZeWu1HLWIDDegK8+EewgSUMFPhkpmA=@vger.kernel.org X-Gm-Message-State: AFuF++n0PMJO2skFDDbvHkHjw41kEXfItxB5qVLnrllw7qnpMSTbmhPE ccSQ2vcUOgIstTsXXkG/ueeVDDMG9iJY6AUQsnVlZjuAbyoBG2HTrM7W X-Gm-Gg: AYBFou0/2LzvMhkzbY6fLSO2bxbj3mwiJK9J2jrSUVbVhLbdmBnXPa6JFs/Nm+KEeLw oGBOUXdeJv6C8SXmpTx/JA23IY74HX48yWH16sWIM3Tn7Yyxhs2EE/50rG0O2r2BSFS5E+H4F1V guRLaR00ekBYuNnenHr3VtflkCw+FtZMsHO7hnlDaWyWnyW1kcKROf7V9/+10gPxW9U1t3ur/PL LV2C7tcFE57lcANTnYvlvBi3utJbUxmviE/74Co5W8zpASG+Lu13rXv6TKmjS+QxtsHE+80D8BC cy+3KAM/O9APQDRfWHJv3hmMs0uQqpbFFLKMDkeOtRgcRd8PL603m+e6EOd5YHxCuYLqSe1tlWR JpXFbsmCGAMOS74ovSC31p6p0fzEZentOzU15oN2G2BrZ6v/riElFj7tlWIQ/SkTBS9H71rsUAO DztomSEInObgM8Ly5XhsF3GFFNv0kE3Kv+h5uzNM/nMCd/QtyMdUCHzvVWvIXJaP6RsVCjUVV4E fQMjGbtZAn73V8j49vYHElDCDcGDail X-Received: by 2002:a05:6300:618d:b0:3dd:a196:69e4 with SMTP id adf61e73a8af0-3dda196784emr12197593637.63.1790012385816; Mon, 21 Sep 2026 10:39:45 -0700 (PDT) Received: from 192.168.50.3 ([198.176.50.208]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-cc72af0955esm3986985a12.32.2026.09.21.10.39.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 21 Sep 2026 10:39:45 -0700 (PDT) From: Weiming Shi To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Martin KaFai Lau , Song Liu , Yonghong Song , Jiri Olsa , Emil Tsalapatis , Ihor Solodrai , John Fastabend , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Shuah Khan Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-kselftest@vger.kernel.org, Xiang Mei , Weiming Shi , stable@vger.kernel.org, Alexei Starovoitov Subject: [PATCH v4 1/2] bpf: clear stale IPv4 options after LWT encapsulation Date: Tue, 22 Sep 2026 01:39:09 +0800 Message-ID: <20260921173910.90847-2-bestswngs@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260921173910.90847-1-bestswngs@gmail.com> References: <20260921173910.90847-1-bestswngs@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit bpf_lwt_push_ip_encap() rebases the network header after prepending an IP header, but leaves IPCB(skb)->opt describing the inner IPv4 header. An ingress LWT route can consequently make an ICMP error use stale option offsets when constructing its reply. Mark completed LWT IP encapsulation in the run's BPF network context and clear stale metadata after bpf_prog_run_save_cb() restores the protocol control block. For same-family IPv4 encapsulation, clear only the cached options, as the IP tunnel transmit paths do. When the family changes, reset the destination family's control block and initialize its ingress interface, following seg6_do_srh_encap(). Save and restore the marker around nested LWT runs. Cc: stable@vger.kernel.org Fixes: 52f278774e79 ("bpf: implement BPF_LWT_ENCAP_IP mode in bpf_lwt_push_encap") Reported-by: Xiang Mei Suggested-by: Daniel Borkmann Suggested-by: Alexei Starovoitov Assisted-by: LLM Signed-off-by: Weiming Shi --- include/linux/filter.h | 1 + net/core/lwt_bpf.c | 30 ++++++++++++++++++++++++++++++ 2 files changed, 31 insertions(+) diff --git a/include/linux/filter.h b/include/linux/filter.h index 39decde7fc73..195898af9528 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -848,6 +848,7 @@ struct bpf_nh_params { #define BPF_RI_F_CPU_MAP_INIT BIT(2) #define BPF_RI_F_DEV_MAP_INIT BIT(3) #define BPF_RI_F_XSK_MAP_INIT BIT(4) +#define BPF_RI_F_LWT_IP_ENCAP BIT(5) struct bpf_redirect_info { u64 tgt_index; diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c index da49364ec63d..88664382ca44 100644 --- a/net/core/lwt_bpf.c +++ b/net/core/lwt_bpf.c @@ -36,10 +36,30 @@ static inline struct bpf_lwt *bpf_lwt_lwtunnel(struct lwtunnel_state *lwt) #define NO_REDIRECT false #define CAN_REDIRECT true +static void bpf_lwt_reset_cb(struct sk_buff *skb, __be16 orig_proto) +{ + if (skb->protocol == orig_proto) { + if (skb->protocol == htons(ETH_P_IP)) + memset(&IPCB(skb)->opt, 0, sizeof(IPCB(skb)->opt)); + return; + } + + if (skb->protocol == htons(ETH_P_IP)) { + memset(IPCB(skb), 0, sizeof(*IPCB(skb))); + IPCB(skb)->iif = skb->skb_iif; + } else if (skb->protocol == htons(ETH_P_IPV6)) { + memset(IP6CB(skb), 0, sizeof(*IP6CB(skb))); + IP6CB(skb)->iif = skb->skb_iif; + } +} + static int run_lwt_bpf(struct sk_buff *skb, struct bpf_lwt_prog *lwt, struct dst_entry *dst, bool can_redirect) { struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx; + struct bpf_redirect_info *ri; + bool lwt_ip_encap, saved_lwt_ip_encap; + __be16 orig_proto = skb->protocol; int ret; /* Disabling BH is needed to protect per-CPU bpf_redirect_info between @@ -47,8 +67,17 @@ static int run_lwt_bpf(struct sk_buff *skb, struct bpf_lwt_prog *lwt, */ local_bh_disable(); bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx); + ri = bpf_net_ctx_get_ri(); + saved_lwt_ip_encap = ri->kern_flags & BPF_RI_F_LWT_IP_ENCAP; + ri->kern_flags &= ~BPF_RI_F_LWT_IP_ENCAP; bpf_compute_data_pointers(skb); ret = bpf_prog_run_save_cb(lwt->prog, skb); + lwt_ip_encap = ri->kern_flags & BPF_RI_F_LWT_IP_ENCAP; + ri->kern_flags &= ~BPF_RI_F_LWT_IP_ENCAP; + if (saved_lwt_ip_encap) + ri->kern_flags |= BPF_RI_F_LWT_IP_ENCAP; + if (lwt_ip_encap) + bpf_lwt_reset_cb(skb, orig_proto); switch (ret) { case BPF_OK: @@ -668,6 +697,7 @@ int bpf_lwt_push_ip_encap(struct sk_buff *skb, void *hdr, u32 len, bool ingress) } else { skb->protocol = htons(ETH_P_IPV6); } + bpf_net_ctx_get_ri()->kern_flags |= BPF_RI_F_LWT_IP_ENCAP; if (skb_is_gso(skb)) return handle_gso_encap(skb, ipv4, len); -- 2.55.0