Messages in this thread | | | Date | Tue, 23 Jun 2009 12:00:40 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] RO/NX protection for loadable kernel modules |
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* James Morris <jmorris@namei.org> wrote:
> On Thu, 18 Jun 2009, Siarhei Liakh wrote: > > > This patch is a logical extension of the protection provided by > > CONFIG_DEBUG_RODATA to LKMs. The protection is provided by splitting > > module_core and module_init into three logical parts each and setting > > appropriate page access permissions for each individual section: > > > > 1. Code: RO+X > > 2. RO data: RO+NX > > 3. RW data: RW+NX > > > > In order to achieve proper protection, layout_sections() have been > > modified to align each of the three parts mentioned above onto page > > boundary. Next, the corresponding page access permissions are set > > right before successful exit from load_module(). Further, > > module_free() have been modified to set module_core or module_init as > > RW+NX right before calling vfree(). Functionality of this patch is > > enabled only when CONFIG_DEBUG_RODATA defined at compile time. > > > > This looks potentially useful to me, but I'm not an x86 expert > (several now added to Cc:).
Pinged a few folks about this already. It looks useful, with the main worry being:
1) the increase in effective module size (probably worth the price) 2) some uglies in the patch (fixable)
The main ugliness is the excessive use of #ifdefs - those should be eliminated. Also, most scripts/checkpatch.pl warnings about this patch should be taken seriously.
Ingo
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