From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
To: "Lena Wang (王娜)" <Lena.Wang@mediatek.com>,
"daniel@iogearbox.net" <daniel@iogearbox.net>,
"maze@google.com" <maze@google.com>,
"willemdebruijn.kernel@gmail.com"
<willemdebruijn.kernel@gmail.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
"steffen.klassert@secunet.com" <steffen.klassert@secunet.com>,
"kuba@kernel.org" <kuba@kernel.org>,
"Shiming Cheng (成诗明)" <Shiming.Cheng@mediatek.com>,
"pabeni@redhat.com" <pabeni@redhat.com>,
"edumazet@google.com" <edumazet@google.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"matthias.bgg@gmail.com" <matthias.bgg@gmail.com>,
"davem@davemloft.net" <davem@davemloft.net>,
"yan@cloudflare.com" <yan@cloudflare.com>
Subject: Re: [PATCH net] udp: fix segmentation crash for GRO packet without fraglist
Date: Sun, 28 Apr 2024 09:19:44 -0400 [thread overview]
Message-ID: <662e4cf0a7ba0_2b6e752941c@willemb.c.googlers.com.notmuch> (raw)
In-Reply-To: <afa6e302244a87c2a834fcc31d48b377e19a34a2.camel@mediatek.com>
Lena Wang (王娜) wrote:
> On Sat, 2024-04-27 at 09:28 -0400, Willem de Bruijn wrote:
> >
> > External email : Please do not click links or open attachments until
> > you have verified the sender or the content.
> >
> > Daniel Borkmann wrote:
> > > On 4/26/24 11:52 AM, Lena Wang (王娜) wrote:
> > > [...]
> > > >>> From 301da5c9d65652bac6091d4cd64b751b3338f8bb Mon Sep 17
> > 00:00:00
> > > >> 2001
> > > >>> From: Shiming Cheng <shiming.cheng@mediatek.com>
> > > >>> Date: Wed, 24 Apr 2024 13:42:35 +0800
> > > >>> Subject: [PATCH net] net: prevent BPF pulling SKB_GSO_FRAGLIST
> > skb
> > > >>>
> > > >>> A SKB_GSO_FRAGLIST skb can't be pulled data
> > > >>> from its fraglist as it may result an invalid
> > > >>> segmentation or kernel exception.
> > > >>>
> > > >>> For such structured skb we limit the BPF pulling
> > > >>> data length smaller than skb_headlen() and return
> > > >>> error if exceeding.
> > > >>>
> > > >>> Fixes: 3a1296a38d0c ("net: Support GRO/GSO fraglist chaining.")
> > > >>> Signed-off-by: Shiming Cheng <shiming.cheng@mediatek.com>
> > > >>> Signed-off-by: Lena Wang <lena.wang@mediatek.com>
> > > >>> ---
> > > >>> net/core/filter.c | 5 +++++
> > > >>> 1 file changed, 5 insertions(+)
> > > >>>
> > > >>> diff --git a/net/core/filter.c b/net/core/filter.c
> > > >>> index 8adf95765cdd..8ed4d5d87167 100644
> > > >>> --- a/net/core/filter.c
> > > >>> +++ b/net/core/filter.c
> > > >>> @@ -1662,6 +1662,11 @@ static DEFINE_PER_CPU(struct
> > bpf_scratchpad,
> > > >>> bpf_sp);
> > > >>> static inline int __bpf_try_make_writable(struct sk_buff
> > *skb,
> > > >>> unsigned int write_len)
> > > >>> {
> > > >>> +if (skb_is_gso(skb) &&
> > > >>> + (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST) &&
> > > >>> + write_len > skb_headlen(skb)) {
> > > >>> +return -ENOMEM;
> > > >>> +}
> > > >>> return skb_ensure_writable(skb, write_len);
> > >
> > > Dumb question, but should this guard be more generically part of
> > skb_ensure_writable()
> > > internals, presumably that would be inside pskb_may_pull_reason(),
> > or only if we ever
> > > see more code instances similar to this?
> >
> > Good point. Most callers of skb_ensure_writable correctly pull only
> > headers, so wouldn't cause this problem. But it also adds coverage to
> > things like tc pedit.
>
> Updated:
>
> From 3be30b8cf6e629f2615ef4eafe3b2a1c0d68c530 Mon Sep 17 00:00:00 2001
> From: Shiming Cheng <shiming.cheng@mediatek.com>
> Date: Sun, 28 Apr 2024 15:03:12 +0800
> Subject: [PATCH net] net: prevent pulling SKB_GSO_FRAGLIST skb
>
> BPF or TC callers may pull in a length longer than skb_headlen()
> for a SKB_GSO_FRAGLIST skb. The data in fraglist will be pulled
> into the linear space. However it destroys the skb's structure
> and may result in an invalid segmentation or kernel exception.
>
> So we should add protection to stop the operation and return
> error to remind callers.
>
> Fixes: 3a1296a38d0c ("net: Support GRO/GSO fraglist chaining.")
> Signed-off-by: Shiming Cheng <shiming.cheng@mediatek.com>
> Signed-off-by: Lena Wang <lena.wang@mediatek.com>
> ---
> include/linux/skbuff.h | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 9d24aec064e8..3eef65b3db24 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -2740,6 +2740,12 @@ pskb_may_pull_reason(struct sk_buff *skb,
> unsigned int len)
pskb_may_pull is called in far too many locations. Daniel's
suggestion was to amend skb_ensure_writable
Please start sending the patches as regular patches. They are close
enough to review normally.
> if (unlikely(len > skb->len))
> return SKB_DROP_REASON_PKT_TOO_SMALL;
>
> + if (skb_is_gso(skb) &&
> + (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST) &&
> + write_len > skb_headlen(skb)) {
> + return SKB_DROP_REASON_NOMEM;
> + }
> +
> if (unlikely(!__pskb_pull_tail(skb, len - skb_headlen(skb))))
> return SKB_DROP_REASON_NOMEM;
>
> --
> 2.18.0
next prev parent reply other threads:[~2024-04-28 13:19 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-15 15:01 [PATCH net] udp: fix segmentation crash for GRO packet without fraglist shiming.cheng
2024-04-15 20:53 ` Willem de Bruijn
2024-04-16 2:14 ` Lena Wang (王娜)
2024-04-16 2:53 ` Maciej Żenczykowski
2024-04-16 17:16 ` Willem de Bruijn
2024-04-16 17:51 ` Maciej Żenczykowski
2024-04-16 17:57 ` Maciej Żenczykowski
2024-04-16 23:14 ` Willem de Bruijn
2024-04-17 7:19 ` Lena Wang (王娜)
2024-04-17 19:48 ` Willem de Bruijn
2024-04-18 2:52 ` Lena Wang (王娜)
2024-04-18 4:15 ` Maciej Żenczykowski
2024-04-19 8:36 ` Lena Wang (王娜)
2024-04-19 14:17 ` Willem de Bruijn
2024-04-19 17:29 ` Maciej Żenczykowski
2024-04-19 17:41 ` Willem de Bruijn
2024-04-23 14:47 ` Lena Wang (王娜)
2024-04-23 18:35 ` Willem de Bruijn
2024-04-24 12:22 ` Lena Wang (王娜)
2024-04-24 14:28 ` Willem de Bruijn
2024-04-25 4:32 ` Lena Wang (王娜)
2024-04-25 14:07 ` Willem de Bruijn
2024-04-26 9:52 ` Lena Wang (王娜)
2024-04-26 21:08 ` Daniel Borkmann
2024-04-27 13:28 ` Willem de Bruijn
2024-04-28 7:48 ` Lena Wang (王娜)
2024-04-28 13:19 ` Willem de Bruijn [this message]
2024-04-29 10:15 ` Daniel Borkmann
2024-04-29 11:45 ` Lena Wang (王娜)
2024-04-29 15:11 ` Daniel Borkmann
2024-04-29 21:14 ` Willem de Bruijn
2024-04-26 0:16 ` Maciej Żenczykowski
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=662e4cf0a7ba0_2b6e752941c@willemb.c.googlers.com.notmuch \
--to=willemdebruijn.kernel@gmail.com \
--cc=Lena.Wang@mediatek.com \
--cc=Shiming.Cheng@mediatek.com \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=davem@davemloft.net \
--cc=edumazet@google.com \
--cc=kuba@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=matthias.bgg@gmail.com \
--cc=maze@google.com \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=steffen.klassert@secunet.com \
--cc=yan@cloudflare.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).