Re: [PATCH v3] audit: Add generic compat syscall support
Catalin,
Let me correct myself,
On 01/27/2014 09:15 PM, Catalin Marinas wrote:
On Mon, Jan 27, 2014 at 05:58:07AM +0000, AKASHI Takahiro wrote:
> Catalin and audit maintainers,
>
> On 01/23/2014 11:51 PM, Catalin Marinas wrote:
>> On Fri, Jan 17, 2014 at 08:03:15AM +0000, AKASHI Takahiro wrote:
>>> diff --git a/lib/compat_audit.c b/lib/compat_audit.c
>>> new file mode 100644
>>> index 0000000..94f6480
>>> --- /dev/null
>>> +++ b/lib/compat_audit.c
>>> @@ -0,0 +1,51 @@
>>> +#include <linux/init.h>
>>> +#include <linux/types.h>
>>> +/* FIXME: this might be architecture dependent */
>>> +#include <asm/unistd_32.h>
>>
>> It most likely is architecture dependent.
>
> I'm wondering what name is the most appropriate in this case.
> Most archictures have __NR_xyz definitions in "unistd_32.h",
> but arm64 doesn't have it, instead "unistd32." which contains
> only __SYSCALL(xyz, NO). Confusing?
I don't think we should introduce a new file (or at least it should be
named something containing "audit" to make it clearer).
>>> +int audit_classify_compat_syscall(int abi, unsigned syscall)
>>> +{
>>> + switch (syscall) {
>>> +#ifdef __NR_open
>>> + case __NR_open:
>>> + return 2;
>>> +#endif
>>> +#ifdef __NR_openat
>>> + case __NR_openat:
>>> + return 3;
>>> +#endif
>>> +#ifdef __NR_socketcall
>>> + case __NR_socketcall:
>>> + return 4;
>>> +#endif
>>> + case __NR_execve:
>>> + return 5;
>>> + default:
>>> + return 1;
>>> + }
>>> +}
>>
>> BTW, since they aren't many, you could get the arch code to define
>> __NR_compat_open etc. explicitly and use these. On arm64 we have a few
>> of these defined to avoid name collision in signal handling code.
>
> Again, most architecture have their own unistd32.h for compat system calls,
> and use __NR_open-like naming.
> It's unlikely for these archs to migrate to "generic compat" auditing,
> but I believe that '__NR_open'-like naming is better because we may be able
to avoid
> arch-specific changes even for future(?) syscall-related enhancements in audit.
In my compat_audit.c, all the entries in audit classes are derived from
asm-generic/audit_*.h,
where __NR_xyz are used to list the system calls. So it is not possible to use
__NR_compat_xyz
as far as we re-use those generic files.
(Obviously we don't want to duplicate those header files, that is, audit_compat_*.h.)
I agree that we should not have similar but different files, like unist32.h and
unistd_32.h,
but it seems to be inevitable for our case. (That is the reason why I dynamically generate
unistd_32.h)
As for arch-specific header file name, "audit_unistd32.h" can be fine, but
people on other architectures
might be unhappy with such a name since they can commonly use unistd32.h instead.
- Takahiro AKASHI
My preference is as above, a few __NR_compat_* (just those required
by
audit) defined in unistd.h but I'm not an audit maintainer.