From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=170.10.133.124 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794493694; b=ckhqnB5qf+8KQa+IFx1l3c5uY3TyO3uRS8U0yb65LgCHELGyRCuTak4a2TUIp/pv7WYf EyWdnsBEdnbzDWIn83kC6cbzs6BXncUSSs9I9K9YeZofDlCSw4QKXiL2rnMj6NwEYkfPq GuzCylUlRrY1eoAuGSC1Ew4I38diT8gud8/pG7j6FeGbUKe1Asg9ivZx+vM8HvQheTIG1 v/hJD3N9nQmNNik6DeOOHIWsyXkVjEj35GC920xKdhkQc2z9W1bOFlP5KC+wHQ8+n9lE/ rp1F/vjAjNUAAyikbvvBP027WHfkX+i0OH7IyERDqAm5tMjsIZ3HgBvOpbRqYqTVv8g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794493694; h=DMARC-Filter:DKIM-Signature:Received:X-MC-Unique: X-Mimecast-MFC-AGG-ID:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received: X-Received:Received:Message-ID:Date:MIME-Version:User-Agent:Subject: To:Cc:References:Content-Language:From:In-Reply-To:Content-Type: Content-Transfer-Encoding; bh=Rc9bf8NN613bIi8UJTLUeEhOmQUWktCfilbKq+1NuLg=; b=jdniRSE3yU75kdDmn8SmY79T3oVxNHK1tibY19t+/6Qorafje8B8iHoSxQI7mDY9efac pp7R2LjELCc1EAfy87wlzEqXF529a1mOx0p442g0CuhRq7Pp23k/zUhw+PPzk+QTIkeTo lKTe0mA8c/Kx69sfudhf6vrDg+TlAPjNIN6EepCHs+g3bwceD8HrElpWVlDI2hGwbGJpq Ae7CNfGdLQ5a9qa6/qtIwMwSlE2yIdo31/nYbJXrxjlLXaRowdDqWH4dUCk/YzkcUFeWk bY3/a6fJvXubjHDGcHOpjKbDP4Rsg2an26+3z+UeghNH4NsdeppEKG6z6za+utzGzSQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=Ch0w08DL; dkim=pass header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=google header.b=XEIeebje; arc=none smtp.remote-ip=170.10.133.124 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A2034606D54C for ; Thu, 12 Nov 2026 14:28:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org A2034606D54C Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=Ch0w08DL; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=google header.b=XEIeebje DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1794493692; 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=Rc9bf8NN613bIi8UJTLUeEhOmQUWktCfilbKq+1NuLg=; b=Ch0w08DLquo/MLe3vXT7N8xsd7o/Jq9FqjHyz1ARzFAyef3kblh5ATY7MpfJnBxIzEZ49F YalEFjvhZiqj4z4KN3OH2moAWP2PXWkAVmdctBw67FvjNcbB7TbVw2csrLSceKEYEu0x3Z hAl1PqKM0I2xFzbatiLdwcBtf8zCRBU= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-120-TfnZj2wiNUKh8BQ2v5MAmA-1; Thu, 12 Nov 2026 09:28:11 -0500 X-MC-Unique: TfnZj2wiNUKh8BQ2v5MAmA-1 X-Mimecast-MFC-AGG-ID: TfnZj2wiNUKh8BQ2v5MAmA_1794493690 Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-4b8b3cd61a5so5243585e9.1 for ; Thu, 12 Nov 2026 06:28:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1794493690; x=1795098490; darn=vger.kernel.org; h=content-transfer-encoding:content-type:in-reply-to:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to :content-type; bh=Rc9bf8NN613bIi8UJTLUeEhOmQUWktCfilbKq+1NuLg=; b=XEIeebjesgm/l0zQ6wDtEuFi5RLFtZgPXWTOOgS/vwHYC2SZzUTH6SiTvBq73tBY6T aDQBm4e1hmHrF0gYjNdg90OITLZx1iCF6NUJ+At7UCG9Z685PIxFk1xEQzEm7UW3hlQc P1Yz0KqQTKX9bqfmFaQY7vuOVCc7QzGue/bkN7a1+WP8oXTCLPi1P8uTbaz3ln/r7lNg RqjmiuqCxuiTviWyP3yia2dPep/TpdQYWJjxyk5Qc2xtbnnK+2y03sCIUg2Cb6IipdDG 3dRl1kXmN1AiiahIV3S0+Rhtv0SzcMa/kGPQrhWrDhShpM58YvCIm7RjBZgccLfoAlfF 9Gfw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1794493690; x=1795098490; h=content-transfer-encoding:content-type:in-reply-to:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=Rc9bf8NN613bIi8UJTLUeEhOmQUWktCfilbKq+1NuLg=; b=WuCz09cn5+sN3EcrzU1KliLJyvtskYezRDWC95neJRiUQbUdv66TKwW7u7hfDcdRdz 4ZlUI3WJF1FT1XsaRQXsWM6MBzc5vbtDCTChWDcSknuBor+7H/8Oq6FR/59OdOpb6PXn Iq6LDyNaiBhn2mrAPi3fBFWf88VIUjH5gN/X+L/3/gIyODApfzVdeEIlpN3bJ7mZXgoA ibAx0ZKOPM6A1BQRc2t2xboE//S2jI0nYujoAI9aSB6LH7iUwS3/avPn5l2GC7kR1zM6 Z3mzZPRLPDzAlvWUHpwOkDZHqCv6IqAjKkAzKFyd5lEvIio6zyBuB7zEBCP4sKd21YTb yjTA== X-Forwarded-Encrypted: i=1; AL+hErHKt7ITFT3vxoBur2IaLBHM9J0PRqYFECN9OHKs2GDlX98FGXiB4qv2QCNyrcaDlfBZ4tVarmo=@vger.kernel.org X-Gm-Message-State: APuU4Z/kNo1neR0jMCh8amqefM9B44/4Qpi/d3pnlNZWI9LwLw3G+QLd zCRB+TkzaGOHui6/fP7vXdKnimYeqBFP/rts3HzfnqOK8I/u9UHgsfmHuIYQaNVsgMIoRJAvRqx 24MJG6dWGSi9AfCNt2fijLMTCS7RIn4HU5jeUN8zjQ4kCDT0rZkhp/ebVmA== X-Gm-Gg: AYBFou23edmg2sCAo8zBVg4exoSAcqpwGhj86zKdZ3/qtczt7F+/jKy8UQADJazCWel aItNNclPo1QlquCMave35wUlSoXMGlL2zuqrKUPTAwAwrea5OAkWn0ulNjcDJJwTRttQwv79hsv 3lazIcwSqNCrjcC7MmEiB72yplxYUCFVbcRSvv9fnQihBrwAytVAXkt/PSauPMmydLe0a7sQSIH euyPYcaNeQsiOqiueuSwq7+/YB7QKUkQMqJywdKsolzwWMYL3+6Y6eLNNgbA5ebVGOCn6cc87b1 EE8ZiA3DlGgsEEMvWv++xlbUJ4jeWBmQ+Hv1SvavpNeoo75In8sSRI8vi/sheh2kOEnHRyQi5S5 +2YRveJjw1F2485ebzqHzXT+oDm/pBlqRUK6T6w0WqMSrTcENcqZiLviJbu8DSYwcFMOuOznioX v14JqIQ6T8vFe4OsZ1N/HSNpvR7KPaDEtnQ5pH+KzOOwiS X-Received: by 2002:a05:600c:8183:b0:4a0:20b4:ba93 with SMTP id 5b1f17b1804b1-4bb4e296cd4mr53828345e9.16.1794493689816; Thu, 12 Nov 2026 06:28:09 -0800 (PST) X-Received: by 2002:a05:600c:8183:b0:4a0:20b4:ba93 with SMTP id 5b1f17b1804b1-4bb4e296cd4mr53827785e9.16.1794493689324; Thu, 12 Nov 2026 06:28:09 -0800 (PST) Received: from [192.168.88.30] (ip231-128-192-82.pool-bba.aruba.it. [82.192.128.231]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4bb51f3cbf9sm40266145e9.0.2026.11.12.06.28.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 12 Nov 2026 06:28:08 -0800 (PST) Message-ID: <2fb8d2d3-9840-4e1f-a02d-877a9b93593a@redhat.com> Date: Thu, 12 Nov 2026 15:28:07 +0100 X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net v2 1/2] ipv4: recompile IP options on a private copy in ipv4_send_dest_unreach() To: Ido Schimmel , Eric Dumazet Cc: "David S . Miller" , Jakub Kicinski , Simon Horman , David Ahern , netdev@vger.kernel.org, Paul Moore , linux-security-module@vger.kernel.org, Kyle Zeng References: <20261109131736.3060756-1-edumazet@kernel.org> <20261109131736.3060756-2-edumazet@kernel.org> <20261112134645.GA3195113@shredder> Content-Language: en-US From: Paolo Abeni In-Reply-To: <20261112134645.GA3195113@shredder> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 11/12/26 14:46, Ido Schimmel wrote: > On Mon, Nov 09, 2026 at 02:17:35PM +0100, Eric Dumazet wrote: >> diff --git a/net/ipv4/route.c b/net/ipv4/route.c >> index 3a90c8d28b940bf615c165d9b30ac634943586e1..9af72cb892034deff2bb3169911c02c025d73cf2 100644 >> --- a/net/ipv4/route.c >> +++ b/net/ipv4/route.c >> @@ -1256,6 +1256,7 @@ EXPORT_INDIRECT_CALLABLE(ipv4_dst_check); >> >> static void ipv4_send_dest_unreach(struct sk_buff *skb) >> { >> + struct sk_buff *nskb = NULL; >> struct inet_skb_parm parm; >> struct net_device *dev; >> int res; >> @@ -1271,6 +1272,16 @@ static void ipv4_send_dest_unreach(struct sk_buff *skb) >> if (ip_hdr(skb)->ihl > 5) { >> if (!pskb_network_may_pull(skb, ip_hdr(skb)->ihl * 4)) >> return; >> + >> + /* __ip_options_compile() writes into the options, and >> + * callers of dst_link_failure() may cache pointers into >> + * skb->head: work on a private copy. >> + */ >> + nskb = pskb_copy(skb, GFP_ATOMIC); >> + if (!nskb) >> + return; >> + skb = nskb; >> + >> parm.opt.optlen = ip_hdr(skb)->ihl * 4 - sizeof(struct iphdr); >> >> rcu_read_lock(); >> @@ -1279,9 +1290,11 @@ static void ipv4_send_dest_unreach(struct sk_buff *skb) >> rcu_read_unlock(); >> >> if (res) >> - return; >> + goto out; >> } >> __icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0, &parm); >> +out: >> + consume_skb(nskb); >> } > > Not sure that what Sashiko describes can happen today, but I wouldn't > rely on the network header not being in the headroom. Something like (on > top of your patch): > > diff --git a/net/ipv4/route.c b/net/ipv4/route.c > index 630143ca0f31..77c03620f89d 100644 > --- a/net/ipv4/route.c > +++ b/net/ipv4/route.c > @@ -1282,6 +1282,10 @@ static void ipv4_send_dest_unreach(struct sk_buff *skb) > if (!pskb_network_may_pull(skb, ip_hdr(skb)->ihl * 4)) > return; > > + /* pskb_copy() does not copy the headroom */ > + if (skb_network_offset(skb) < 0) > + return; > + > /* __ip_options_compile() writes into the options, and > * callers of dst_link_failure() may cache pointers into > * skb->head: work on a private copy. I think the above makes sense. /P