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Date: Thu, 16 Feb 2012 20:12:12 -0800
From: "H. Peter Anvin" <hpa@...or.com>
To: Will Drewry <wad@...omium.org>
CC: Eric Paris <eparis@...hat.com>, Markus Gutschke <markus@...omium.org>,
linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
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Subject: Re: [PATCH v8 3/8] seccomp: add system call filtering using BPF
On 02/16/2012 07:53 PM, Will Drewry wrote:
>
> An earlier change Roland had prodded me toward was adding a
> syscall_get_arch() call to asm/syscall.h which returned the
> appropriate audit arch value for the current calling convention. I
> hate to suggest this, but should I go ahead and wire that up for x86
> now, make it a dependency for HAVE_ARCH_SECCOMP_FILTER (and officially
> part of asm/syscall.h) then let it trickle into existence? Maybe
> something like:
>
... and we have been talking about making a regset and export it to
ptrace and core dumps, too.
> static inline int syscall_get_arch(struct task_struct *task, struct
> pt_regs *regs)
> {
> #ifdef CONFIG_IA32_EMULATION
> if (task_thread_info(task)->status & TS_COMPAT)
> return AUDIT_ARCH_I386;
> #endif
> #ifdef CONFIG_64BIT
> return AUDIT_ARCH_X86_64;
> #else
> return AUDIT_ARCH_I386;
> #endif
> }
>
In this case it could be is_compat_task().
> There would be no other callers, though, because everywhere AUDIT_ARCH
> is used it is hardcoded as appropriate. Then when x32 comes along, it
> can figure out where it belongs using tif status and/or regs.
For x32 you have the option of introducing a new value or relying on bit
30 in eax (and AUDIT_ARCH_X86_64). The latter is more natural, probably.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
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