Re: [PATCH] kernel: make /proc/kallsyms mode 400 to reduce ease ofattacking
From: Ingo Molnar
Date: Fri Nov 26 2010 - 02:49:09 EST
* Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Fri, Nov 19, 2010 at 11:19 AM, Sarah Sharp
> <sarah.a.sharp@xxxxxxxxxxxxxxx> wrote:
> >
> > .config and dmesg are attached. The box is running klogd 1.5.5ubuntu3
> > (from Jaunty). Yes, I know that's old. I read the bit in the commit
> > about changing the permissions of kallsyms after boot, but if I can't
> > boot that doesn't help. Perhaps this can be made a configuration
> > option?
>
> It's not worth a config option.
>
> If it actually breaks user-space, I think we should just revert it.
Sarah,
Does your system boot fine if we make /proc/kallsyms simply an empty file to
unprivileged users? Something like the (untested ...) patch below.
Ingo
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 6f6d091..d54c993 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -465,7 +465,7 @@ static int s_show(struct seq_file *m, void *p)
struct kallsym_iter *iter = m->private;
/* Some debugging symbols have no name. Ignore them. */
- if (!iter->name[0])
+ if (!iter->name[0] || !capable(CAP_SYS_ADMIN))
return 0;
if (iter->module_name[0]) {
--
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