Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 29 Nov 2010 08:33:24 -0800 | From | Sarah Sharp <> | Subject | Re: [PATCH] kernel: make /proc/kallsyms mode 400 to reduce ease of attacking |
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On Fri, Nov 26, 2010 at 08:48:09AM +0100, Ingo Molnar wrote: > > * Linus Torvalds <torvalds@linux-foundation.org> wrote: > > > On Fri, Nov 19, 2010 at 11:19 AM, Sarah Sharp > > <sarah.a.sharp@linux.intel.com> 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.
Yes, that works. The system boots as normal. `cat /proc/kallsyms` returns an empty file, and `sudo cat /proc/kallsyms` does not.
Sarah Sharp
> 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]) { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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