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From: David Miller <davem@davemloft.net>
To: mathew.j.martineau@linux.intel.com
Cc: netdev@vger.kernel.org, mptcp@lists.01.org, ast@kernel.org,
	daniel@iogearbox.net, bpf@vger.kernel.org, pabeni@redhat.com,
	matthieu.baerts@tessares.net
Subject: Re: [PATCH net-next v7 02/11] sock: Make sk_protocol a 16-bit value
Date: Thu, 09 Jan 2020 11:05:14 -0800 (PST)	[thread overview]
Message-ID: <20200109.110514.747612850299504416.davem@davemloft.net> (raw)
In-Reply-To: <20200109155924.30122-3-mathew.j.martineau@linux.intel.com>

From: Mat Martineau <mathew.j.martineau@linux.intel.com>
Date: Thu,  9 Jan 2020 07:59:15 -0800

> Match the 16-bit width of skbuff->protocol. Fills an 8-bit hole so
> sizeof(struct sock) does not change.
> 
> Also take care of BPF field access for sk_type/sk_protocol. Both of them
> are now outside the bitfield, so we can use load instructions without
> further shifting/masking.
> 
> v5 -> v6:
>  - update eBPF accessors, too (Intel's kbuild test robot)
> v2 -> v3:
>  - keep 'sk_type' 2 bytes aligned (Eric)
> v1 -> v2:
>  - preserve sk_pacing_shift as bit field (Eric)
> 
> Cc: Alexei Starovoitov <ast@kernel.org>
> Cc: Daniel Borkmann <daniel@iogearbox.net>
> Cc: bpf@vger.kernel.org
> Co-developed-by: Paolo Abeni <pabeni@redhat.com>
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> Co-developed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
> Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
> Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>

This is worrisome for me.

We have lots of places that now are going to be assigning  sk->sk_protocol
into a u8 somewhere else.  A lot of them are ok because limits are enforced
in various places, but for example:

net/ipv6/udp.c:	fl6.flowi6_proto = sk->sk_protocol;
net/l2tp/l2tp_ip6.c:	fl6.flowi6_proto = sk->sk_protocol;

net/ipv6/inet6_connection_sock.c:	fl6->flowi6_proto = sk->sk_protocol;

net/ipv6/af_inet6.c:		fl6.flowi6_proto = sk->sk_protocol;
net/ipv6/datagram.c:	fl6->flowi6_proto = sk->sk_protocol;

This is one just one small example situation, where flowi6_proto is a u8.

  reply	other threads:[~2020-01-09 19:05 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-09 15:59 [PATCH net-next v7 00/11] Multipath TCP: Prerequisites Mat Martineau
2020-01-09 15:59 ` [PATCH net-next v7 01/11] net: Make sock protocol value checks more specific Mat Martineau
2020-01-09 15:59 ` [PATCH net-next v7 02/11] sock: Make sk_protocol a 16-bit value Mat Martineau
2020-01-09 19:05   ` David Miller [this message]
2020-01-09 21:25     ` [MPTCP] " Florian Westphal
2020-01-10  2:43       ` David Miller
2020-01-09 15:59 ` [PATCH net-next v7 03/11] tcp: Define IPPROTO_MPTCP Mat Martineau
2020-01-09 15:59 ` [PATCH net-next v7 04/11] tcp: Add MPTCP option number Mat Martineau
2020-01-09 15:59 ` [PATCH net-next v7 05/11] tcp, ulp: Add clone operation to tcp_ulp_ops Mat Martineau
2020-01-09 15:59 ` [PATCH net-next v7 06/11] mptcp: Add MPTCP to skb extensions Mat Martineau
2020-01-09 15:59 ` [PATCH net-next v7 07/11] tcp: coalesce/collapse must respect MPTCP extensions Mat Martineau
2020-01-09 15:59 ` [PATCH net-next v7 08/11] tcp: Export TCP functions and ops struct Mat Martineau
2020-01-09 15:59 ` [PATCH net-next v7 09/11] tcp: Check for filled TCP option space before SACK Mat Martineau
2020-01-09 15:59 ` [PATCH net-next v7 10/11] tcp: clean ext on tx recycle Mat Martineau
2020-01-09 15:59 ` [PATCH net-next v7 11/11] skb: add helpers to allocate ext independently from sk_buff Mat Martineau
2020-01-10  2:44 ` [PATCH net-next v7 00/11] Multipath TCP: Prerequisites David Miller

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