From: Jakub Kicinski <kuba@kernel.org>
To: David Laight <David.Laight@ACULAB.COM>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"David S . Miller" <davem@davemloft.net>,
"eric.dumazet@gmail.com" <eric.dumazet@gmail.com>,
"martin.lau@linux.dev" <martin.lau@linux.dev>,
Alexei Starovoitov <ast@kernel.org>,
"Stephen Hemminger" <stephen@networkplumber.org>,
Jens Axboe <axboe@kernel.dk>,
"Daniel Borkmann" <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>
Subject: Re: [PATCH net-next 0/4] sockptr: Change sockptr_t to be a struct
Date: Tue, 2 Jan 2024 14:32:20 -0800 [thread overview]
Message-ID: <20240102143220.3068951d@kernel.org> (raw)
In-Reply-To: <199c9af56a5741feaf4b1768bf7356be@AcuMS.aculab.com>
On Mon, 25 Dec 2023 09:46:23 +0000 David Laight wrote:
> The original commit for sockptr_t tried to use the pointer value
> to determine whether a pointer was user or kernel.
> This can't work on some architectures and was buggy on x86.
> So the is_kernel discriminator was added after the union of pointers.
>
> However this is still open to misuse and accidents.
> Replace the union with a struct and remove the is_kernel member.
> The user and kernel values are now in different places.
> The structure size doesn't change - it was always padded out to 'two pointers'.
>
> The only functional difference is that NULL pointers are always 'user'.
> So dereferencing will (usually) fault in copy_from_user() rather than
> panic if supplied as a kernel address.
>
> Simple driver code that uses kernel sockets still works.
> I've not tested bpf - but that should work unless it is breaking
> the rules.
LGTM, but we either need acks from bpf folks or route this via
bpf-next. So please repost and CC bpf@ on the whole series.
prev parent reply other threads:[~2024-01-02 22:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-25 9:46 [PATCH net-next 0/4] sockptr: Change sockptr_t to be a struct David Laight
2023-12-25 9:51 ` [PATCH net-next 1/4] net: Use sockptr_is_kernel() instead of testing is_kernel David Laight
2023-12-25 9:55 ` [PATCH net-next 2/4] bpf: Use bpfptr_is_kernel() instead of checking the is_kernel member David Laight
2023-12-25 9:57 ` [PATCH net-next 3/4] bpf: Use the sockptr_t helpers David Laight
2023-12-25 9:58 ` [PATCH net-next 4/4] sockptr: Change sockptr_t to be a struct of a kernel and user pointer David Laight
2024-01-02 22:32 ` Jakub Kicinski [this message]
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