Date: Mon, 28 Mar 2005 17:41:19 -0500 From: John Baldwin <jhb@FreeBSD.org> To: "Jeremy Messenger" <mezz7@cox.net> Cc: arch@FreeBSD.org Subject: Re: Fixing DRM after phk's drive-by axeing Message-ID: <200503281741.19443.jhb@FreeBSD.org> In-Reply-To: <opsodc8tjq9aq2h7@mezz.mezzweb.com> References: <200503281734.45926.jhb@FreeBSD.org> <opsodc8tjq9aq2h7@mezz.mezzweb.com>
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On Monday 28 March 2005 05:39 pm, Jeremy Messenger wrote: > On Mon, 28 Mar 2005 17:34:45 -0500, John Baldwin <jhb@FreeBSD.org> wrote: > > I have a commit-ready version of the vm_mmap() changes I made to get drm > > to > > work happily with the newer, cleaner cdev stuff that phk has been > > working on. > > Basically, I've changed vm_mmap() so that it can accept either a vnode > > or a > > cdev as its handle argument rather than just vnodes. For the cdev case, > > it > > calls a vm_mmap_cdev() function that is a cut down version of > > vm_mmap_vnode(). One thing to note is that this case loses the MAC > > check for > > this type of mmap() (currently only done from DRM) since MAC only checks > > mmaps for vnodes. If cdev were to grow a label, then a mmap check for > > the > > cdev could be added I suppose, though the case of a mmap'ing a vnode that > > maps to a cdev would have to be adjusted to make that extra call as well. > > > > The first cut at the patch added a new MAP_CDEV flag to vm_mmap() that > > specified that the handle argument was a cdev rather than a vnode. > > However, > > this method requires that any kernel code that calls vm_mmap() passing in > > flags from userland has to verify that MAP_CDEV isn't passed in from > > userland > > to avoid potential DOSs from random user processes that result in kernel > > panics. Thus, I decided to change vm_mmap() to instead take a objtype_t > > parameter that specifies what type of object the handle argument is. > > Thus, > > for MAP_ANON, the code passes in OBJT_DEFAULT, for vnodes OBJT_VNODE, > > and for > > cdevs (in drm) OBJT_DEVICE. I've stuck the patch at > > http://www.FreeBSD.org/~jhb/patches/mmap_cdev3.patch and am using it > > locally > > You had it typo for ',' instead '.'.. mmap_cdev3,patch > > http://people.freebsd.org/~jhb/patches/mmap_cdev3,patch > > Cheers, > Mezz Heh, fixed. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org
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