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SubjectRe: Testers wanted: exorcised kmod.c: no more daemon!
>> = Adam J. Richter
> = Craig Milo Rogers

>> o If you want autoloading of modules from anonymous FTP
>> for some reason, you must make a copy of /sbin/modprobe
>> and lib/modules/<kernel_version> accessible from the
>> anonymous FTP area, as you already do with the executables
>> shared libraries if you want to use them from anonymous
>> FTP sessions.

> Ugh! But this sounds like you'd just opened a wound in
>security. I can imagine circumstances in which someone might want to
>allow an anonymous FTP user to access data through a path that
>requires an autoloaded kernel module, but loading kernel modules from
>the anonymous FTP area itself??? Even if the kernel module files have
>file protections that prevent access by the anonymous FTP server's
>processes in normal conditions, you've created an outstanding way to
>infect the kernel and take over the system if that first layer of
>protection is broken.

> Can you think of a way to allow some chroot's, such as boot
>device changes, to be followed, while disallowing other ones?

You could do that by creating system call for that purpose, and
adding a module_root field to task_struct or perhaps just add a
disable_kmod flag.

A different approach that would not increase the size or
complexity of task_struct would be to make request_module require that
the modprobe program be owned by uid 0 and not writable by anyone
else, and have modprobe enforce the same requirement on the module .o
files. Since the anonymous FTP program is set to some other userid,
it cannot create such a file.

I welcome other ideas and, better yet, patches.

Adam J. Richter __ ______________ 4880 Stevens Creek Blvd, Suite 205
adam@yggdrasil.com \ / San Jose, California 95129-1034
+1 408 261-6630 | g g d r a s i l United States of America
fax +1 408 261-6631 "Free Software For The Rest Of Us."

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