Re: [PATCH 1/9] Known exploit detection

Sasha Levin
2013-12-16T05:18:21Z

Hi Vegard,

On 12/12/2013 11:52 AM, vegard.nossum@oracle.com wrote:
> +#ifdef CONFIG_EXPLOIT_DETECTION
> +extern void _exploit(const char *id);

So right now the on/off switch is a kernel config option. I suggest we should add another
dynamic switch (maybe in the form of jump labels) to add an additional level of control:

- It will allow having an opt-in option. Right now users are forced into
having this feature if the distro maintainers enable it.
- Which means that distro maintainers are less likely to enable it.

- If the SHTF and there's something wrong we would want a way to disable it
without having to re-compile the kernel.

<bikeshedding>
Also,

Maybe in the future we could enable/disable specific exploits based on severity or certainty
(how likely that this specific activity is an exploit attempt).

</bikeshedding>

On 12/12/2013 11:52 AM, vegard.nossum@oracle.com wrote:
> +#define exploit_on(cond, id) \
> + do { \
> + if (unlikely(cond)) \
> + _exploit(id); \
> + } while (0)

What if we make exploit_on() something like this:

#define exploit_on(cond, id) ({ \
int __ret_exploit_on = !!(cond); \
if (unlikely(__ret_exploit_on)) \
_exploit(id); \
unlikely(__ret_exploit_on); \
})

That way we can use it within if() conditionals similar to WARN_ON:

if (exploit_on(srclen > HFS_NAMELEN, "CVE-2011-4330"))
srclen = HFS_NAMELEN;

Thanks,
Sasha