From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yx1-f48.google.com (mail-yx1-f48.google.com [74.125.224.48]) (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 B048829ACF6 for ; Wed, 18 Mar 2026 20:02:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.224.48 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773864177; cv=none; b=B9SHWbFeVoNA/lA7mTIk+gwF5HTeWsJ44fEyAWOdbz3KoE+0ks2OlhXeMMYDzyGfTX/21oMcS5mwFch1bxPks9nzFodK2INiyF/glAkWM8kPKnMgggTRu/6FIzrmXl9bBFR/ZmgnF8vmMrkR8TSQoX/AFTCV4uvdLe+qbRxt+WA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773864177; c=relaxed/simple; bh=cMCaVXNr7qfEfiS9Zxjes22PtZsQF6QDYQ+CpJPrpvo=; h=Date:From:To:Cc:Message-ID:In-Reply-To:References:Subject: Mime-Version:Content-Type; b=rsAEamxUUHObOOwZ0W72yZKRMYEQGjISilXZA/LpyEYhT/+ov354rldo6f4mUcHyBl6z2ML5XB1Ru9d18G/mbu713uuHmdsHu3AvEExlTfx1AtvkBziwt3NScHLDCJvBJ/IrZlg8hHqpIwgEiH9xRkCzN1LOpwVPTISwKrkENIg= 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=JbKs5NPK; arc=none smtp.client-ip=74.125.224.48 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="JbKs5NPK" Received: by mail-yx1-f48.google.com with SMTP id 956f58d0204a3-64d5a7926cfso385404d50.2 for ; Wed, 18 Mar 2026 13:02:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1773864176; x=1774468976; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:subject:references :in-reply-to:message-id:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=3BGJyg89KVjKDhlLon0g7DLh+7sfd3j1XaPbD798/2Q=; b=JbKs5NPKR+VmuZ5DA58w+uFYFmT/HICtg4kwVVIG0QsZDZGeFIGmFlLmt0AIqtxJiL MTjP4+n8mL4LCk/0Wbkcz15HidudHCX9vwXeXRYehAXKLxV7YEcU9zC3CS0DQn44Lk/f QDtDrYCLtdYiSy8oupHW/NDpxJjUXT+aU9Jhc5jzJt1SVETOjyRkqrrSV8xhp/E//+bE jg/wo1w3fUhWHWoHu1ku9nWMYv+uWdbs7m8zFNcIZMsOa/GJOS3DNlGkvhRGl+jujRUh 95usvCWmGIVtKVTW09SRaCssrL02vKWxhkfJeHWugGkix3iUX6eHpIesrR3HMKXe/qsR 6ZnQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1773864176; x=1774468976; h=content-transfer-encoding:mime-version:subject:references :in-reply-to:message-id:cc:to:from:date:x-gm-gg:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=3BGJyg89KVjKDhlLon0g7DLh+7sfd3j1XaPbD798/2Q=; b=sPISeRl5vRifXKh9OPDlS0XopFkssJGgJfVJ9raosL+yNLOhP9HCw2m13VUnMFGeGh mMD0H/fJ0NBLX4h6qJJ7CspiZ4NdMqcW6jQ7bs6TD3w5mGrQmQ5LDLlq8Qd2tGzU6pGJ N4HQxAmR2BfLVnABSIJIYlfLj/6+tCKAS8pMU5ZyO8euG2euclzlcJ4V/m400jKfV8oC L0fBCZtgsH4ygrDpWlGoXam0sP5UUlooFXQ4m32sUxbEf+b3OKrrotiAK2UWF/m14moh 4eYHg0Ge6vwy1V34iJoadO33DsPoZjwr/+gzD0C3TdNpPdF2CwAQLCNopHG7NQbH3f+B kFoA== X-Forwarded-Encrypted: i=1; AJvYcCVX17Pt8neWjRVBp+Tn29W5Vd/Aq3Kt04S7KIqJUM4OcKILKnfpJUHmuLohEEaNk+W76LcqwMu/b+DHD1k=@vger.kernel.org X-Gm-Message-State: AOJu0YwVcN0U77V1/Ac3UXMQWvUJM2Y52dozrgtfzzMqAI4aRWhfHQPG dFF7SL/J2Y5OfDYCFqSfUnYM1tAoR0PR4g5/X/RwVA8Y4+u2uaH77QCi X-Gm-Gg: ATEYQzwZQU/fyBLLpjEX9YqAoIzmugoEK7MIX0Llv1wZUarht7Cn1UvuIe+gars4cFA zZNxlWz+V0bW9sSs6UhqLQj9Xxywesz2FPGyqBePlnKBRxoaxy+z4gyj7RO4qvSUeWp3BpGb1UN 78qAdp338yAK4jh4nPHV9pybxDyYoO/xKlN1XpGGvOQmxywhcFpTmqBGrvHzIDFejaKTEC5A/sN RsDW1gQ7eFKZVUiApyBVvvvQuPG/vhnM7o37pNQXNaomR5SeI6bTwezM3xZwTaonMyeUiGU/nXG 5Z09GgFUq52S677AWAlBRSD91ktg7lO+2tzKoV4nyqhs6sSrY3R8eTop8E2L1+9+co6zOwOkyWW I64+qrBexOBAFE9hfqVN4C4nxHpROpp/VdhziGRsdera3/3e2uGpJaTV5DfY+PaYlFt6niNbNoo BH90VbgPfEGVi9irY5GR/ko0CUV3ExpPOqphjqdcPBWDRZ6S4Zi6VSrOt38WxWZ2hRgkt5D6yck ek/ X-Received: by 2002:a05:690e:389:b0:64c:2207:52a3 with SMTP id 956f58d0204a3-64e916162camr3569426d50.64.1773864175609; Wed, 18 Mar 2026 13:02:55 -0700 (PDT) Received: from gmail.com (180.134.85.34.bc.googleusercontent.com. [34.85.134.180]) by smtp.gmail.com with UTF8SMTPSA id 956f58d0204a3-64e91be032asm2180679d50.14.2026.03.18.13.02.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Mar 2026 13:02:55 -0700 (PDT) Date: Wed, 18 Mar 2026 16:02:54 -0400 From: Willem de Bruijn To: Nick Hudson , bpf@vger.kernel.org, netdev@vger.kernel.org Cc: Willem de Bruijn , Nick Hudson , Max Tottenham , Anna Glasgall , Martin KaFai Lau , Daniel Borkmann , Alexei Starovoitov , Andrii Nakryiko , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-kernel@vger.kernel.org Message-ID: In-Reply-To: <20260318134242.2725749-5-nhudson@akamai.com> References: <20260318134242.2725749-1-nhudson@akamai.com> <20260318134242.2725749-5-nhudson@akamai.com> Subject: Re: [PATCH v2 4/5] bpf: allow new DECAP flags and add guard rails Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Nick Hudson wrote: > Add checks to require shrink-only decap, reject conflicting decap flag > combinations, and verify removed length is sufficient for claimed header > decapsulation. > > Co-developed-by: Max Tottenham > Signed-off-by: Max Tottenham > Co-developed-by: Anna Glasgall > Signed-off-by: Anna Glasgall > Signed-off-by: Nick Hudson > --- > net/core/filter.c | 47 +++++++++++++++++++++++++++++++++++++---------- > 1 file changed, 37 insertions(+), 10 deletions(-) > > diff --git a/net/core/filter.c b/net/core/filter.c > index 7c2871b40fe4..47aec44a9cd3 100644 > --- a/net/core/filter.c > +++ b/net/core/filter.c > @@ -56,6 +56,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -3496,7 +3497,9 @@ static u32 bpf_skb_net_base_len(const struct sk_buff *skb) > BPF_F_ADJ_ROOM_ENCAP_L2( \ > BPF_ADJ_ROOM_ENCAP_L2_MASK)) > > -#define BPF_F_ADJ_ROOM_DECAP_MASK (BPF_F_ADJ_ROOM_DECAP_L3_MASK) > +#define BPF_F_ADJ_ROOM_DECAP_MASK (BPF_F_ADJ_ROOM_DECAP_L3_MASK | \ > + BPF_F_ADJ_ROOM_DECAP_L4_MASK | \ > + BPF_F_ADJ_ROOM_DECAP_IPXIP_MASK) > > #define BPF_F_ADJ_ROOM_MASK (BPF_F_ADJ_ROOM_FIXED_GSO | \ > BPF_F_ADJ_ROOM_ENCAP_MASK | \ > @@ -3743,20 +3746,44 @@ BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff, > return -ENOTSUPP; > } > > - if (flags & BPF_F_ADJ_ROOM_DECAP_L3_MASK) { > + if (flags & BPF_F_ADJ_ROOM_DECAP_MASK) { > + u32 len_decap_min = 0; > + > if (!shrink) > return -EINVAL; > > - switch (flags & BPF_F_ADJ_ROOM_DECAP_L3_MASK) { > - case BPF_F_ADJ_ROOM_DECAP_L3_IPV4: > + /* Reject mutually exclusive decap flag pairs. */ > + if ((flags & BPF_F_ADJ_ROOM_DECAP_L3_MASK) == > + BPF_F_ADJ_ROOM_DECAP_L3_MASK) > + return -EINVAL; > + > + if ((flags & BPF_F_ADJ_ROOM_DECAP_L4_MASK) == > + BPF_F_ADJ_ROOM_DECAP_L4_MASK) > + return -EINVAL; > + > + if ((flags & BPF_F_ADJ_ROOM_DECAP_IPXIP_MASK) == > + BPF_F_ADJ_ROOM_DECAP_IPXIP_MASK) > + return -EINVAL; > + > + /* Reject mutually exclusive decap tunnel type flags. */ > + if ((flags & BPF_F_ADJ_ROOM_DECAP_L4_MASK) && > + (flags & BPF_F_ADJ_ROOM_DECAP_IPXIP_MASK)) > + return -EINVAL; > + > + if (flags & BPF_F_ADJ_ROOM_DECAP_L4_UDP) > + len_decap_min += sizeof(struct udphdr); > + > + if (flags & BPF_F_ADJ_ROOM_DECAP_L4_GRE) > + len_decap_min += sizeof(struct gre_base_hdr); > + > + if (len_diff_abs < len_decap_min) > + return -EINVAL; Should this test come after the below IP flags? > + > + if (flags & BPF_F_ADJ_ROOM_DECAP_L3_IPV4) > len_min = sizeof(struct iphdr); > - break; > - case BPF_F_ADJ_ROOM_DECAP_L3_IPV6: > + > + if (flags & BPF_F_ADJ_ROOM_DECAP_L3_IPV6) > len_min = sizeof(struct ipv6hdr); > - break; > - default: > - return -EINVAL; > - } > } > > len_cur = skb->len - skb_network_offset(skb); > -- > 2.34.1 >