From: Martin KaFai Lau <martin.lau@linux.dev>
To: "Hudson, Nick" <nhudson@akamai.com>
Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
"Tottenham, Max" <mtottenh@akamai.com>,
"Glasgall, Anna" <aglasgal@akamai.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 3/5] bpf: add helper masks for ADJ_ROOM flags and encap validation
Date: Thu, 26 Mar 2026 10:49:14 -0700 [thread overview]
Message-ID: <c0c453f9-28aa-462f-884d-0e9beb2fdf0a@linux.dev> (raw)
In-Reply-To: <9E9BE3BD-1640-49E7-8801-130945073B24@akamai.com>
On 3/26/26 10:02 AM, Hudson, Nick wrote:
>>> static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff,
>>> u64 flags)
>>> @@ -3502,6 +3513,11 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff,
>>> unsigned int gso_type = SKB_GSO_DODGY;
>>> int ret;
>>> + if (unlikely(flags & ~(BPF_F_ADJ_ROOM_ENCAP_MASK |
>>> + BPF_F_ADJ_ROOM_NO_CSUM_RESET |
>>> + BPF_F_ADJ_ROOM_FIXED_GSO)))
>> Under which case this new check will be hit?
> If a user supplies +ve len_diff and attempts to pass a DECAP flag.
>
> The commit message had
>
> Add flag validation to bpf_skb_net_grow() to reject invalid encap
> flags early.
There is DECAP_MASK check in bpf_skb_adjust_room() and then !shrink is
rejected. What am I missing?
next prev parent reply other threads:[~2026-03-26 17:49 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-18 13:42 [PATCH v2 0/5] bpf: skb_adjust_room helper refactor and tunnel decap flags Nick Hudson
2026-03-18 13:42 ` [PATCH v2 1/5] bpf: name the enum for BPF_FUNC_skb_adjust_room flags Nick Hudson
2026-03-21 0:39 ` Willem de Bruijn
2026-03-24 17:34 ` Martin KaFai Lau
2026-03-18 13:42 ` [PATCH v2 2/5] bpf: add BPF_F_ADJ_ROOM_DECAP_* flags for tunnel decapsulation Nick Hudson
2026-03-21 0:39 ` Willem de Bruijn
2026-03-18 13:42 ` [PATCH v2 3/5] bpf: add helper masks for ADJ_ROOM flags and encap validation Nick Hudson
2026-03-21 0:39 ` Willem de Bruijn
2026-03-24 18:12 ` Martin KaFai Lau
2026-03-26 17:02 ` Hudson, Nick
2026-03-26 17:49 ` Martin KaFai Lau [this message]
2026-03-18 13:42 ` [PATCH v2 4/5] bpf: allow new DECAP flags and add guard rails Nick Hudson
2026-03-18 20:02 ` Willem de Bruijn
2026-03-19 8:17 ` Hudson, Nick
2026-03-19 13:24 ` Willem de Bruijn
2026-03-21 0:40 ` Willem de Bruijn
2026-03-24 18:30 ` Martin KaFai Lau
2026-03-26 17:02 ` Hudson, Nick
2026-03-18 13:42 ` [PATCH v2 5/5] bpf: clear decap tunnel GSO state in skb_adjust_room Nick Hudson
2026-03-18 20:09 ` Willem de Bruijn
2026-03-18 20:01 ` [PATCH v2 0/5] bpf: skb_adjust_room helper refactor and tunnel decap flags Willem de Bruijn
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