Messages in this thread | | | Date | Fri, 9 May 2003 17:24:36 +0200 | From | Pavel Machek <> | Subject | Re: ioctl32_unregister_conversion & modules |
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Hi!
> > ...what is the problem? > > > > It seems that function pointers into modules do not need any special > > treatmeant [I *know* there was talk about this on l-k; but I can't > > find anything in Documentation/]: > > > > if (!capable(CAP_SYS_ADMIN)) > > return -EACCES; > > if (disk->fops->ioctl) { > > ret = disk->fops->ioctl(inode, file, cmd, arg); > > if (ret != -EINVAL) > > return ret; > > } > > This is protected against unload by the reference counting done in > open()/release(). ->ioctl() can be called only for open devices, > so you know the ioctl handler is not getting unloaded while it > is running. > > > So... what's the problem with {un}register_ioctl32_conversion being > > called from module_init/module_exit? Drivers in the tree do it > > already... > > The problem is that when the conversion handler is called, the reference > counting is only done for the module listed as ->owner in the > file operations. For example in the patch you submitted to add > register_ioctl32_conversion() to drivers/serial/core.c I see nothing > stopping you from unloading core.ko while the handler is running > on a device owned by drivers/char/cyclades.c or any other serial driver. > It does not even have to be run on a serial driver, a user might try > to do ioctl(TIOCGSERIAL, ...) on a regular file...
Oh.... Yep, that's pretty clear.
So what you are saying is that all existing register_ioctl32_conversion-s that are in unloadable module are broken. Ouch.
Fixing that would require resgister_ioctl32_conversion() to have 3-rd parameter "this module" and some magic inside fs/compat_ioctl.c, right?
Pavel -- When do you have a heart between your knees? [Johanka's followup: and *two* hearts?] - 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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