linux-kernel - Re: [PATCH -v2] Audit: push audit success and retcode into arch ptrace.h

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Message-Id: <201106050036.44852.richard@nod.at>
Date:	Sun, 5 Jun 2011 00:36:44 +0200
From:	Richard Weinberger <richard@....at>
To:	Eric Paris <eparis@...hat.com>
Cc:	linux-kernel@...r.kernel.org, tony.luck@...el.com,
	fenghua.yu@...el.com, monstr@...str.eu, ralf@...ux-mips.org,
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	akpm@...ux-foundation.org, linux-ia64@...r.kernel.org,
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	user-mode-linux-devel@...ts.sourceforge.net
Subject: Re: [PATCH -v2] Audit: push audit success and retcode into arch ptrace.h

Am Samstag 04 Juni 2011, 00:04:51 schrieb Eric Paris:
> The audit system previously expected arches calling to audit_syscall_exit
> to supply as arguments if the syscall was a success and what the return
> code was. Audit also provides a helper AUDITSC_RESULT which was supposed
> to simplify things by converting from negative retcodes to an audit
> internal magic value stating success or failure.  This helper was wrong
> and could indicate that a valid pointer returned to userspace was a failed
> syscall.  The fix is to fix the layering foolishness.  We now pass
> audit_syscall_exit a struct pt_reg and it in turns calls back into arch
> code to collect the return value and to determine if the syscall was a
> success or failure.  We also define a generic is_syscall_success() macro
> which determines success/failure based on if the value is < -MAX_ERRNO. 
> This works for arches like x86 which do not use a separate mechanism to
> indicate syscall failure.
> 
> In arch/sh/kernel/ptrace_64.c I see that we were using regs[9] in the old
> audit code as the return value.  But the ptrace_64.h code defined the macro
> regs_return_value() as regs[3].  I have no idea which one is correct, but
> this patch now uses the regs_return_value() function, so it now uses
> regs[3].
> 
> We make both the is_syscall_success() and regs_return_value() static
> inlines instead of macros.  The reason is because the audit function must
> take a void* for the regs.  (uml calls theirs struct uml_pt_regs instead
> of just struct pt_regs so audit_syscall_exit can't take a struct pt_regs).
>  Since the audit function takes a void* we need to use static inlines to
> cast it back to the arch correct structure to dereference it.
> 
> The other major change is that on some arches, like ia64, we change
> regs_return_value() to give us the negative value on syscall failure.  The
> only other user of this macro, kretprobe_example.c, won't notice and it
> makes the value signed consistently for the audit functions across all
> archs.
> 
> Signed-off-by: Eric Paris <eparis@...hat.com>
> Acked-by: Acked-by: H. Peter Anvin <hpa@...or.com> [for x86 portion]

The UML part is now fine for me. :-)

Acked-by: Richard Weinberger <richard@....at>

Thanks,
//richard
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