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From: David Laight <David.Laight@ACULAB.COM>
To: 'Christoph Hellwig' <hch@lst.de>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	Eric Dumazet <edumazet@google.com>
Cc: "linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
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Subject: RE: [PATCH 03/24] net: add a new sockptr_t type
Date: Tue, 21 Jul 2020 10:14:20 +0000
Message-ID: <6727969f2f6e467fa2d43f9773cefa27@AcuMS.aculab.com> (raw)
In-Reply-To: <20200720124737.118617-4-hch@lst.de>

From: Christoph Hellwig
> Sent: 20 July 2020 13:47
> 
> Add a uptr_t type that can hold a pointer to either a user or kernel
> memory region, and simply helpers to copy to and from it.  For
> architectures like x86 that have non-overlapping user and kernel
> address space it just is a union and uses a TASK_SIZE check to
> select the proper copy routine.  For architectures with overlapping
> address spaces a flag to indicate the address space is used instead.
> 
...
> +#else /* CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE */
> +typedef struct {
> +	union {
> +		void		*kernel;
> +		void __user	*user;
> +	};
> +	bool		is_kernel : 1;
> +} sockptr_t;

If you need to do that you might as well make it a struct
where either the kernel or user address is defined.
Far safer for all architectures.

Indeed you could add the length (to save passing an
extra parameter through the layers).

The system call code could even copy the code into a
kernel buffer (setting both pointers).
So that code that didn't need to access beyond the end
of the implied buffer (most of it) could just access the
kernel buffer.

For getsockopt() you'd need some way of supressing the
'default' copy back of the user buffer.

This would also allow some of the sctp getsockopt to
read (usually 4 bytes) from the 'user' buffer without
the wrapper code always having to read in the entire
user buffer.

	David

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Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)


  parent reply index

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-20 12:47 get rid of the address_space override in setsockopt Christoph Hellwig
2020-07-20 12:47 ` [PATCH 01/24] bpfilter: reject kernel addresses Christoph Hellwig
2020-07-20 12:47 ` [PATCH 02/24] bpfilter: fix up a sparse annotation Christoph Hellwig
2020-07-21  2:40   ` Luc Van Oostenryck
2020-07-21  5:23     ` Christoph Hellwig
2020-07-21  5:28       ` Al Viro
2020-07-20 12:47 ` [PATCH 03/24] net: add a new sockptr_t type Christoph Hellwig
2020-07-20 16:37   ` Eric Biggers
2020-07-20 17:43     ` Christoph Hellwig
2020-07-20 17:55       ` Eric Biggers
2020-07-22  7:56         ` Christoph Hellwig
2020-07-21  9:55     ` David Laight
2020-07-21 10:14   ` David Laight [this message]
2020-07-20 12:47 ` [PATCH 04/24] net: switch copy_bpf_fprog_from_user to sockptr_t Christoph Hellwig
2020-07-20 12:47 ` [PATCH 05/24] net: switch sock_setbindtodevice " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 06/24] net: switch sock_set_timeout " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 07/24] " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 08/24] net/xfrm: switch xfrm_user_policy " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 09/24] netfilter: remove the unused user argument to do_update_counters Christoph Hellwig
2020-07-20 12:47 ` [PATCH 10/24] netfilter: switch xt_copy_counters to sockptr_t Christoph Hellwig
2020-07-20 12:47 ` [PATCH 11/24] netfilter: switch nf_setsockopt " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 12/24] bpfilter: switch bpfilter_ip_set_sockopt " Christoph Hellwig
2020-07-21  8:36   ` David Laight
2020-07-22  8:00     ` 'Christoph Hellwig'
2020-07-22  8:01       ` 'Christoph Hellwig'
2020-07-20 12:47 ` [PATCH 13/24] net/ipv4: switch ip_mroute_setsockopt " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 14/24] net/ipv4: merge ip_options_get and ip_options_get_from_user Christoph Hellwig
2020-07-20 12:47 ` [PATCH 15/24] net/ipv4: switch do_ip_setsockopt to sockptr_t Christoph Hellwig
2020-07-20 12:47 ` [PATCH 16/24] net/ipv6: switch ip6_mroute_setsockopt " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 17/24] net/ipv6: split up ipv6_flowlabel_opt Christoph Hellwig
2020-07-20 12:47 ` [PATCH 18/24] net/ipv6: switch ipv6_flowlabel_opt to sockptr_t Christoph Hellwig
2020-07-20 12:47 ` [PATCH 19/24] net/ipv6: factor out a ipv6_set_opt_hdr helper Christoph Hellwig
2020-07-20 12:47 ` [PATCH 20/24] net/ipv6: switch do_ipv6_setsockopt to sockptr_t Christoph Hellwig
2020-07-20 12:47 ` [PATCH 21/24] net/udp: switch udp_lib_setsockopt " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 22/24] net/tcp: switch ->md5_parse " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 23/24] net/tcp: switch do_tcp_setsockopt " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 24/24] net: pass a sockptr_t into ->setsockopt Christoph Hellwig
2020-07-20 14:19   ` Stefan Schmidt
2020-07-20 23:20     ` David Miller
2020-07-22  8:26   ` [MPTCP] " Matthieu Baerts
2020-07-20 16:38 ` get rid of the address_space override in setsockopt Eric Biggers
2020-07-20 17:43   ` Christoph Hellwig
2020-07-20 20:47 ` Alexei Starovoitov
2020-07-22  7:56   ` Christoph Hellwig
2020-07-22 17:09     ` Alexei Starovoitov
2020-07-21  9:38 ` David Laight
2020-07-22  8:06   ` 'Christoph Hellwig'
2020-07-22  8:21     ` David Laight
2020-07-21 10:26 ` David Laight
2020-07-22  8:07   ` 'Christoph Hellwig'

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