netdev - Re: [PATCH net-next v2] Use READ/WRITE_ONCE() for IP local_port

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <f9d3e1dd-133a-45de-827e-c2f152b619b8@kernel.org>
Date: Wed, 6 Dec 2023 09:39:06 -0700
From: David Ahern <dsahern@...nel.org>
To: David Laight <David.Laight@...LAB.COM>,
 "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Cc: Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 "David S. Miller" <davem@...emloft.net>,
 Stephen Hemminger <stephen@...workplumber.org>,
 "jakub@...udflare.com" <jakub@...udflare.com>,
 Eric Dumazet <edumazet@...gle.com>, 'Mat Martineau' <martineau@...nel.org>
Subject: Re: [PATCH net-next v2] Use READ/WRITE_ONCE() for IP
 local_port_range.

On 12/6/23 6:44 AM, David Laight wrote:
> Commit 227b60f5102cd added a seqlock to ensure that the low and high
> port numbers were always updated together.
> This is overkill because the two 16bit port numbers can be held in
> a u32 and read/written in a single instruction.
> 
> More recently 91d0b78c5177f added support for finer per-socket limits.
> The user-supplied value is 'high << 16 | low' but they are held
> separately and the socket options protected by the socket lock.
> 
> Use a u32 containing 'high << 16 | low' for both the 'net' and 'sk'
> fields and use READ_ONCE()/WRITE_ONCE() to ensure both values are
> always updated together.
> 
> Change (the now trival) inet_get_local_port_range() to a static inline
> to optimise the calling code.
> (In particular avoiding returning integers by reference.)
> 
> Signed-off-by: David Laight <david.laight@...lab.com>
> ---
> Changes for v2:
> - minor layout changes.
> - remove unlikely() from comparisons when per-socket range set.
> - avoid shifts of signed values that generate unsigned 32bit results.
> I fiddled with the code that validates the argument to IP_LOCAL_PORT_RANGE
> then decided to leave it (mostly) unchanged because it is also moved.
> (There is a 'u16 x = int_val >> 16' which is required to move bit 31 to
> bit 15 and is probably undefined behaviour - but will be ok on all sane cpu.)
> 
>  include/net/inet_sock.h         |  5 +----
>  include/net/ip.h                |  8 +++++++-
>  include/net/netns/ipv4.h        |  3 +--
>  net/ipv4/af_inet.c              |  4 +---
>  net/ipv4/inet_connection_sock.c | 29 ++++++++++-------------------
>  net/ipv4/ip_sockglue.c          | 33 ++++++++++++++++-----------------
>  net/ipv4/sysctl_net_ipv4.c      | 18 +++++++-----------
>  7 files changed, 43 insertions(+), 57 deletions(-)
> 

Reviewed-by: David Ahern <dsahern@...nel.org>