Re: [PATCH v4 02/21] kallsyms: Export kallsyms_lookup_name

Greg KH
2023-06-28T15:43:33Z

On Wed, Jun 28, 2023 at 04:32:47PM +0100, Will Deacon wrote:
> On Wed, Jun 28, 2023 at 08:52:57PM +0530, Mukesh Ojha wrote:
> >
> >
> > On 6/28/2023 7:23 PM, Pavan Kondeti wrote:
> > > On Wed, Jun 28, 2023 at 06:04:29PM +0530, Mukesh Ojha wrote:
> > > > Module like minidump providing debugging support will need to
> > > > get the symbol information from the core kernel e.g to get
> > > > the linux_banner, kernel section addresses bss, data, ro etc.
> > > >
> > > One might ask why we would need such a debug driver to
> > > be compiled as module? What would you do if we need to capture more
> > > kernel data structures later? Do you plan to continue use
> > > kallsyms_lookup_name() to query all the symbols?
> >
> > You are on point, i needed this driver to be static but i don't have
> > any example at present to collect more than just _linux_banner_ from
> > my existing set of patches..
> >
> > Agree, it will be easier to make this driver as static instead of
> > opening up the doors for modules to abuse via exporting
> > kallsyms_lookup_name() and also it will be very slow for production
> > kernel uses.
>
> Right, I unexported that symbol deliberately in 0bd476e6c671 ("kallsyms:
> unexport kallsyms_lookup_name() and kallsyms_on_each_symbol()") and I
> don't think we should add it back for this driver.

I agree, it shouldn't be needed by any in-kernel module/driver. If you
really want the name, look it up afterward in userspace :)

thanks,

greg k-h