From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-171.mta1.migadu.com (out-171.mta1.migadu.com [95.215.58.171]) (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 25C64A32 for ; Tue, 6 May 2025 19:17:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746559062; cv=none; b=UvGhh6bTTinzVxLnBujRfxwoJ7H3jNFnqgx/0utz4mauOW752kIYm09i0Qo1dmmbFbfYhzL5X+4AyanIFcTFKN5AuzGhUkUvfqb7bac63jaBsnRhG1axHsNoimlh4mlNFM9h9PW6tesh17pylET1lcpoF/yix+1FzujRUyqqjL8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746559062; c=relaxed/simple; bh=VHUqiD05FcopIn9Isg3UQtJIAdEvCJnbRkQXXA6U+9Q=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=eLhEELPPNj54jGLFPK7eEkkF6Qi2BZ4XRMPOrM+GZC/CbmNSMcxE+wPeSb1IzAe6dDrzMbOU4KNTMAtusgHRG1Q5LZ+CTPY+MuzT5f4ZXXR/kylK7JuvEgRgQ3owAA7ZU8mhPEvljvokVRMVG9BRnvgljEPgK5KszgFJ7UqdsWE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=MRcn4LxB; arc=none smtp.client-ip=95.215.58.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="MRcn4LxB" Message-ID: <73cccd5e-de7d-404b-910d-c6a799c28c57@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1746559048; 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=dCjtMGqu+X6qdS0ItwJy140Bxn7tOeJGMS9JpXz7MB0=; b=MRcn4LxBPt75uL26KlkS8uY9EOMoAGGewxejrCdhDqUqglbxCM7G1smGAvIkMrKOeuT5jA St6xRz30l7glGQ6VAFoy+aMH3RV1Pu4QDt7xAwXdakD6HVMGtBuXSpIXNVO8KKqHcLLoXl 4WoyaOH7bNcBKcOo0pmLP5QSjjHa7CU= Date: Tue, 6 May 2025 12:17:13 -0700 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf v2 1/2] bpf: Scrub packet on bpf_redirect_peer To: Paul Chaignon Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Jakub Kicinski , Network Development , bpf@vger.kernel.org References: <1728ead5e0fe45e7a6542c36bd4e3ca07a73b7d6.1746460653.git.paul.chaignon@gmail.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Martin KaFai Lau Content-Language: en-US In-Reply-To: <1728ead5e0fe45e7a6542c36bd4e3ca07a73b7d6.1746460653.git.paul.chaignon@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 5/5/25 12:58 PM, Paul Chaignon wrote: > When bpf_redirect_peer is used to redirect packets to a device in > another network namespace, the skb isn't scrubbed. That can lead skb > information from one namespace to be "misused" in another namespace. > > As one example, this is causing Cilium to drop traffic when using > bpf_redirect_peer to redirect packets that just went through IPsec > decryption to a container namespace. The following pwru trace shows (1) > the packet path from the host's XFRM layer to the container's XFRM > layer where it's dropped and (2) the number of active skb extensions at > each function. > > NETNS MARK IFACE TUPLE FUNC > 4026533547 d00 eth0 10.244.3.124:35473->10.244.2.158:53 xfrm_rcv_cb > .active_extensions = (__u8)2, > 4026533547 d00 eth0 10.244.3.124:35473->10.244.2.158:53 xfrm4_rcv_cb > .active_extensions = (__u8)2, > 4026533547 d00 eth0 10.244.3.124:35473->10.244.2.158:53 gro_cells_receive > .active_extensions = (__u8)2, > [...] > 4026533547 0 eth0 10.244.3.124:35473->10.244.2.158:53 skb_do_redirect > .active_extensions = (__u8)2, > 4026534999 0 eth0 10.244.3.124:35473->10.244.2.158:53 ip_rcv > .active_extensions = (__u8)2, > 4026534999 0 eth0 10.244.3.124:35473->10.244.2.158:53 ip_rcv_core > .active_extensions = (__u8)2, > [...] > 4026534999 0 eth0 10.244.3.124:35473->10.244.2.158:53 udp_queue_rcv_one_skb > .active_extensions = (__u8)2, > 4026534999 0 eth0 10.244.3.124:35473->10.244.2.158:53 __xfrm_policy_check > .active_extensions = (__u8)2, > 4026534999 0 eth0 10.244.3.124:35473->10.244.2.158:53 __xfrm_decode_session > .active_extensions = (__u8)2, > 4026534999 0 eth0 10.244.3.124:35473->10.244.2.158:53 security_xfrm_decode_session > .active_extensions = (__u8)2, > 4026534999 0 eth0 10.244.3.124:35473->10.244.2.158:53 kfree_skb_reason(SKB_DROP_REASON_XFRM_POLICY) > .active_extensions = (__u8)2, > > In this case, there are no XFRM policies in the container's network > namespace so the drop is unexpected. When we decrypt the IPsec packet, > the XFRM state used for decryption is set in the skb extensions. This > information is preserved across the netns switch. When we reach the > XFRM policy check in the container's netns, __xfrm_policy_check drops > the packet with LINUX_MIB_XFRMINNOPOLS because a (container-side) XFRM > policy can't be found that matches the (host-side) XFRM state used for > decryption. > > This patch fixes this by scrubbing the packet when using > bpf_redirect_peer, as is done on typical netns switches via veth > devices except skb->mark and skb->tstamp are not zeroed. > > Fixes: 9aa1206e8f482 ("bpf: Add redirect_peer helper") > Signed-off-by: Paul Chaignon Acked-by: Martin KaFai Lau