From: Steffen Klassert <steffen.klassert@secunet.com>
To: Fan Du <fan.du@windriver.com>
Cc: <davem@davemloft.net>, <netdev@vger.kernel.org>
Subject: Re: [PATCH net-next] xfrm: Correctly parse netlink msg from 32bits ip command on 64bits host
Date: Thu, 20 Feb 2014 10:59:34 +0100 [thread overview]
Message-ID: <20140220095934.GF32371@secunet.com> (raw)
In-Reply-To: <1392801176-2656-1-git-send-email-fan.du@windriver.com>
On Wed, Feb 19, 2014 at 05:12:56PM +0800, Fan Du wrote:
>
> +#ifdef CONFIG_COMPAT
> +
> +struct compat_xfrm_userpolicy_info {
> + struct xfrm_selector sel;
> + struct xfrm_lifetime_cfg lft;
> + struct xfrm_lifetime_cur curlft;
> + __u32 priority;
> + __u32 index;
> + __u8 dir;
> + __u8 action;
> +#define XFRM_POLICY_ALLOW 0
> +#define XFRM_POLICY_BLOCK 1
> + __u8 flags;
> +#define XFRM_POLICY_LOCALOK 1 /* Allow user to override global policy */
> + /* Automatically expand selector to include matching ICMP payloads. */
> +#define XFRM_POLICY_ICMP 2
> + __u8 share;
> +} __attribute__((packed));
> +
> +struct compat_xfrm_usersa_info {
> + struct xfrm_selector sel;
> + struct xfrm_id id;
> + xfrm_address_t saddr;
> + struct xfrm_lifetime_cfg lft;
> + struct xfrm_lifetime_cur curlft;
> + struct xfrm_stats stats;
> + __u32 seq;
> + __u32 reqid;
> + __u16 family;
> + __u8 mode; /* XFRM_MODE_xxx */
> + __u8 replay_window;
> + __u8 flags;
> +#define XFRM_STATE_NOECN 1
> +#define XFRM_STATE_DECAP_DSCP 2
> +#define XFRM_STATE_NOPMTUDISC 4
> +#define XFRM_STATE_WILDRECV 8
> +#define XFRM_STATE_ICMP 16
> +#define XFRM_STATE_AF_UNSPEC 32
> +#define XFRM_STATE_ALIGN4 64
> +#define XFRM_STATE_ESN 128
> +} __attribute__((packed));
> +
You define two structures that you actually don't use,
all you do is checking their size.
The only reason why this works is because these two
structures differ only on some padding bytes at the
end. If we want to support 32 bit ipsec tools on
64 bit kernels, we need a complete compat layer
for all the userspace exported structures.
A lot of userspace exported structures differ not only
on some padding bytes at the end.
For example the layout of xfrm_userspi_info:
on 32 bit:
struct xfrm_userspi_info {
struct xfrm_usersa_info info; /* 0 220 */
/* XXX last struct has 3 bytes of padding */
/* --- cacheline 3 boundary (192 bytes) was 28 bytes ago --- */
__u32 min; /* 220 4 */
__u32 max; /* 224 4 */
/* size: 228, cachelines: 4, members: 3 */
/* paddings: 1, sum paddings: 3 */
/* last cacheline: 36 bytes */
};
on 64 bit:
struct xfrm_userspi_info {
struct xfrm_usersa_info info; /* 0 224 */
/* XXX last struct has 7 bytes of padding */
/* --- cacheline 3 boundary (192 bytes) was 32 bytes ago --- */
__u32 min; /* 224 4 */
__u32 max; /* 228 4 */
/* size: 232, cachelines: 4, members: 3 */
/* paddings: 1, sum paddings: 7 */
/* last cacheline: 40 bytes */
};
So the 'min' field has an offest of 220 bytes on 32 bit and an offset
of 224 bytes on 64 bit. We would need a compatability layer like we
have it for system calls to map this correct.
For now I think we should just refuse to do anything if someone tries
to configure ipsec with 32 bit tools on a 64 bit machine.
next prev parent reply other threads:[~2014-02-20 9:59 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-19 9:12 [PATCH net-next] xfrm: Correctly parse netlink msg from 32bits ip command on 64bits host Fan Du
2014-02-20 9:59 ` Steffen Klassert [this message]
2014-02-25 6:41 ` Fan Du
2014-02-25 11:53 ` Steffen Klassert
2014-02-25 17:15 ` Ben Hutchings
2014-02-25 19:16 ` Florian Westphal
2014-02-27 23:52 ` David Miller
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