From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from www62.your-server.de (www62.your-server.de [213.133.104.62]) (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 7BC143C9EFE for ; Mon, 27 Apr 2026 13:30:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.133.104.62 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777296645; cv=none; b=epy0xlcfJVzXjvxRLPUseoP5Ft1Jq+9c97ZPIIEUMxBOMGp+rH+WymboKShLHeKYQluIGnJ20MT9rZMyvPDI8w+PsAxaqj2F9+LSReBVOTomGVdYFIj1zg6bDay0C1eDFbeiB00wosGtgc/OVtGvF5OwWeIuTwgfGeSpwUrpTpI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777296645; c=relaxed/simple; bh=6Ehm7GKjS5t3zI3Cc/FObefiBO4HEDiewmYBaWtIapg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=D0yEiEph0P2f6V8N+gAz559SfI0ETxUrwI92CWDcdEGK0/uFPzM5eJANgHPSQ0h2E+8et+izfsnUVnxtzaLcg/V0og4SguaMfmayPbu4omgkL5nfRfLrkzJeVztBbKHJbA7kjMsZrBlXLl7KWbVQZpoNNwSZmGE8lsC0RLCLl6I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=iogearbox.net; spf=pass smtp.mailfrom=iogearbox.net; dkim=pass (2048-bit key) header.d=iogearbox.net header.i=@iogearbox.net header.b=G/TPunds; arc=none smtp.client-ip=213.133.104.62 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=iogearbox.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iogearbox.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=iogearbox.net header.i=@iogearbox.net header.b="G/TPunds" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=iogearbox.net; s=default2302; h=Content-Transfer-Encoding:Content-Type: In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date:Message-ID:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID; bh=GoASsGD1zVHTJpV/gIWHpGRnBtWLatN98+RGlz2jC9g=; b=G/TPundso3aCrmdPhQeLjAeSvT emLKvLZYQEEaUcYD3O33+cLKlXm1d9a3wnOd6S9OQ6ak3YddCItUu0Ne2C3x/yvJFhrCQDl0uEm7f XtEdJF8D9jZ2KbJFT5kn95IrJ1u8Y3Y0ipVPJ8lD2N8TlAp7ACiIZoeCemH5ZGo9mVT2fUexQTxwq dgtwHy5hN5aRiuJidTdFqrZI5qHvadChLU4Sx6si6fKmBK6m0S6GYQUAwQj2ac9QDWTssOZWnBsQX yZ3Oy0770b9cUZzcbMvK9q0RSOuIEIGn/A0wCrCuv2DpFO0AK6qVf8nXwv68ellYcr9imVTuV8pic W58xHZbw==; Received: from sslproxy08.your-server.de ([78.47.166.52]) by www62.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.96.2) (envelope-from ) id 1wHM2j-000CWI-1L; Mon, 27 Apr 2026 15:30:33 +0200 Received: from localhost ([127.0.0.1]) by sslproxy08.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1wHM2h-000HGq-3D; Mon, 27 Apr 2026 15:30:32 +0200 Message-ID: Date: Mon, 27 Apr 2026 15:30:32 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net v3] ipv6: Implement limits on extension header parsing To: David Laight Cc: kuba@kernel.org, edumazet@google.com, dsahern@kernel.org, tom@herbertland.com, willemdebruijn.kernel@gmail.com, idosch@nvidia.com, justin.iurman@gmail.com, pabeni@redhat.com, netdev@vger.kernel.org References: <20260427101318.750730-1-daniel@iogearbox.net> <20260427141449.4bc90a28@pumpkin> Content-Language: en-US From: Daniel Borkmann Autocrypt: addr=daniel@iogearbox.net; keydata= xsFNBGNAkI0BEADiPFmKwpD3+vG5nsOznvJgrxUPJhFE46hARXWYbCxLxpbf2nehmtgnYpAN 2HY+OJmdspBntWzGX8lnXF6eFUYLOoQpugoJHbehn9c0Dcictj8tc28MGMzxh4aK02H99KA8 VaRBIDhmR7NJxLWAg9PgneTFzl2lRnycv8vSzj35L+W6XT7wDKoV4KtMr3Szu3g68OBbp1TV HbJH8qe2rl2QKOkysTFRXgpu/haWGs1BPpzKH/ua59+lVQt3ZupePpmzBEkevJK3iwR95TYF 06Ltpw9ArW/g3KF0kFUQkGXYXe/icyzHrH1Yxqar/hsJhYImqoGRSKs1VLA5WkRI6KebfpJ+ RK7Jxrt02AxZkivjAdIifFvarPPu0ydxxDAmgCq5mYJ5I/+BY0DdCAaZezKQvKw+RUEvXmbL 94IfAwTFA1RAAuZw3Rz5SNVz7p4FzD54G4pWr3mUv7l6dV7W5DnnuohG1x6qCp+/3O619R26 1a7Zh2HlrcNZfUmUUcpaRPP7sPkBBLhJfqjUzc2oHRNpK/1mQ/+mD9CjVFNz9OAGD0xFzNUo yOFu/N8EQfYD9lwntxM0dl+QPjYsH81H6zw6ofq+jVKcEMI/JAgFMU0EnxrtQKH7WXxhO4hx 3DFM7Ui90hbExlFrXELyl/ahlll8gfrXY2cevtQsoJDvQLbv7QARAQABzSZEYW5pZWwgQm9y a21hbm4gPGRhbmllbEBpb2dlYXJib3gubmV0PsLBkQQTAQoAOxYhBCrUdtCTcZyapV2h+93z cY/jfzlXBQJjQJCNAhsDBQkHhM4ACAsJCAcNDAsKBRUKCQgLAh4BAheAAAoJEN3zcY/jfzlX dkUQAIFayRgjML1jnwKs7kvfbRxf11VI57EAG8a0IvxDlNKDcz74mH66HMyhMhPqCPBqphB5 ZUjN4N5I7iMYB/oWUeohbuudH4+v6ebzzmgx/EO+jWksP3gBPmBeeaPv7xOvN/pPDSe/0Ywp dHpl3Np2dS6uVOMnyIsvmUGyclqWpJgPoVaXrVGgyuer5RpE/a3HJWlCBvFUnk19pwDMMZ8t 0fk9O47HmGh9Ts3O8pGibfdREcPYeGGqRKRbaXvcRO1g5n5x8cmTm0sQYr2xhB01RJqWrgcj ve1TxcBG/eVMmBJefgCCkSs1suriihfjjLmJDCp9XI/FpXGiVoDS54TTQiKQinqtzP0jv+TH 1Ku+6x7EjLoLH24ISGyHRmtXJrR/1Ou22t0qhCbtcT1gKmDbTj5TcqbnNMGWhRRTxgOCYvG0 0P2U6+wNj3HFZ7DePRNQ08bM38t8MUpQw4Z2SkM+jdqrPC4f/5S8JzodCu4x80YHfcYSt+Jj ipu1Ve5/ftGlrSECvy80ZTKinwxj6lC3tei1bkI8RgWZClRnr06pirlvimJ4R0IghnvifGQb M1HwVbht8oyUEkOtUR0i0DMjk3M2NoZ0A3tTWAlAH8Y3y2H8yzRrKOsIuiyKye9pWZQbCDu4 ZDKELR2+8LUh+ja1RVLMvtFxfh07w9Ha46LmRhpCzsFNBGNAkI0BEADJh65bNBGNPLM7cFVS nYG8tqT+hIxtR4Z8HQEGseAbqNDjCpKA8wsxQIp0dpaLyvrx4TAb/vWIlLCxNu8Wv4W1JOST wI+PIUCbO/UFxRy3hTNlb3zzmeKpd0detH49bP/Ag6F7iHTwQQRwEOECKKaOH52tiJeNvvyJ pPKSKRhmUuFKMhyRVK57ryUDgowlG/SPgxK9/Jto1SHS1VfQYKhzMn4pWFu0ILEQ5x8a0RoX k9p9XkwmXRYcENhC1P3nW4q1xHHlCkiqvrjmWSbSVFYRHHkbeUbh6GYuCuhqLe6SEJtqJW2l EVhf5AOp7eguba23h82M8PC4cYFl5moLAaNcPHsdBaQZznZ6NndTtmUENPiQc2EHjHrrZI5l kRx9hvDcV3Xnk7ie0eAZDmDEbMLvI13AvjqoabONZxra5YcPqxV2Biv0OYp+OiqavBwmk48Z P63kTxLddd7qSWbAArBoOd0wxZGZ6mV8Ci/ob8tV4rLSR/UOUi+9QnkxnJor14OfYkJKxot5 hWdJ3MYXjmcHjImBWplOyRiB81JbVf567MQlanforHd1r0ITzMHYONmRghrQvzlaMQrs0V0H 5/sIufaiDh7rLeZSimeVyoFvwvQPx5sXhjViaHa+zHZExP9jhS/WWfFE881fNK9qqV8pi+li 2uov8g5yD6hh+EPH6wARAQABwsF8BBgBCgAmFiEEKtR20JNxnJqlXaH73fNxj+N/OVcFAmNA kI0CGwwFCQeEzgAACgkQ3fNxj+N/OVfFMhAA2zXBUzMLWgTm6iHKAPfz3xEmjtwCF2Qv/TT3 KqNUfU3/0VN2HjMABNZR+q3apm+jq76y0iWroTun8Lxo7g89/VDPLSCT0Nb7+VSuVR/nXfk8 R+OoXQgXFRimYMqtP+LmyYM5V0VsuSsJTSnLbJTyCJVu8lvk3T9B0BywVmSFddumv3/pLZGn 17EoKEWg4lraXjPXnV/zaaLdV5c3Olmnj8vh+14HnU5Cnw/dLS8/e8DHozkhcEftOf+puCIl Awo8txxtLq3H7KtA0c9kbSDpS+z/oT2S+WtRfucI+WN9XhvKmHkDV6+zNSH1FrZbP9FbLtoE T8qBdyk//d0GrGnOrPA3Yyka8epd/bXA0js9EuNknyNsHwaFrW4jpGAaIl62iYgb0jCtmoK/ rCsv2dqS6Hi8w0s23IGjz51cdhdHzkFwuc8/WxI1ewacNNtfGnorXMh6N0g7E/r21pPeMDFs rUD9YI1Je/WifL/HbIubHCCdK8/N7rblgUrZJMG3W+7vAvZsOh/6VTZeP4wCe7Gs/cJhE2gI DmGcR+7rQvbFQC4zQxEjo8fNaTwjpzLM9NIp4vG9SDIqAm20MXzLBAeVkofixCsosUWUODxP owLbpg7pFRJGL9YyEHpS7MGPb3jSLzucMAFXgoI8rVqoq6si2sxr2l0VsNH5o3NgoAgJNIg= In-Reply-To: <20260427141449.4bc90a28@pumpkin> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: Clear (ClamAV 1.4.3/27984/Mon Apr 27 08:24:37 2026) On 4/27/26 3:14 PM, David Laight wrote: > On Mon, 27 Apr 2026 12:13:18 +0200 > Daniel Borkmann wrote: [...] >> --- >> v2->v3: >> - Adding IP6SKB_HOPBYHOP coverage (Justin) >> - I left the limit at 8 w/ sysctl, still feels the better >> option to me if we can keep the worst-case more tightened >> v1->v2: >> - Set the default to 8 (Justin) >> - Update IETF references (Justin) >> - Add core path coverage as well (Justin) > ... >> @@ -72,7 +74,9 @@ EXPORT_SYMBOL(ipv6_ext_hdr); >> int ipv6_skip_exthdr(const struct sk_buff *skb, int start, u8 *nexthdrp, >> __be16 *frag_offp) >> { >> + int exthdr_max = READ_ONCE(init_net.ipv6.sysctl.max_ext_hdrs_cnt); >> u8 nexthdr = *nexthdrp; >> + int exthdr_cnt = 0; >> >> *frag_offp = 0; >> >> @@ -82,6 +86,8 @@ int ipv6_skip_exthdr(const struct sk_buff *skb, int start, u8 *nexthdrp, >> >> if (nexthdr == NEXTHDR_NONE) >> return -1; >> + if (unlikely(exthdr_cnt++ >= exthdr_max)) >> + return -1; > > It would be better to decrement the count and error at zero. > if (unlikely(--exthdr_max < 0)) > return -1; Well, its in the same style as the other existing gating counters, I'd rather leave as-is rather than mixing inc/decs. Thanks, Daniel