From: Paolo Abeni <pabeni@redhat.com>
To: Eric Dumazet <eric.dumazet@gmail.com>,
"David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>
Cc: netdev <netdev@vger.kernel.org>, Eric Dumazet <edumazet@google.com>
Subject: Re: [PATCH net-next] net: warn if mac header was not set
Date: Tue, 21 Jun 2022 11:21:28 +0200 [thread overview]
Message-ID: <58f36d9554cb3dd19d52373f9496cd230ed48423.camel@redhat.com> (raw)
In-Reply-To: <20220620093017.3366713-1-eric.dumazet@gmail.com>
Hello,
On Mon, 2022-06-20 at 02:30 -0700, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google.com>
>
> Make sure skb_mac_header(), skb_mac_offset() and skb_mac_header_len() uses
> are not fooled if the mac header has not been set.
>
> These checks are enabled if CONFIG_DEBUG_NET=y
>
> This commit will likely expose existing bugs in linux networking stacks.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> ---
> include/linux/skbuff.h | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 82edf0359ab32d0d7cd583676b38d569ce0b24cc..cd4a8268894acce4bde16dc0fedb7eb13706f515 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -2763,8 +2763,14 @@ static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
> skb->network_header += offset;
> }
>
> +static inline int skb_mac_header_was_set(const struct sk_buff *skb)
> +{
> + return skb->mac_header != (typeof(skb->mac_header))~0U;
> +}
> +
> static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
> {
> + DEBUG_NET_WARN_ON_ONCE(!skb_mac_header_was_set(skb));
> return skb->head + skb->mac_header;
> }
>
> @@ -2775,14 +2781,10 @@ static inline int skb_mac_offset(const struct sk_buff *skb)
>
> static inline u32 skb_mac_header_len(const struct sk_buff *skb)
> {
> + DEBUG_NET_WARN_ON_ONCE(!skb_mac_header_was_set(skb));
The patch LGTM.
I'm wondering if it's worthy adding similar debug checks for network
and transport offset (with more patches). e.g. still in
skb_mac_header_len():
DEBUG_NET_WARN_ON_ONCE(skb->network_header < skb->mac_header);
Thanks!
Paolo
next prev parent reply other threads:[~2022-06-21 9:21 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-20 9:30 [PATCH net-next] net: warn if mac header was not set Eric Dumazet
2022-06-21 9:21 ` Paolo Abeni [this message]
2022-06-21 9:40 ` patchwork-bot+netdevbpf
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