DragonFly submit List (threaded) for 2008-01
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Re: vnconfig -l support patch (Re: vn(4) RFC Misc.)
:Per my recent email to kernel@, Attached is a little patch to get
:vnconfig to list configured / available vn devices adapted from
:& imho improved from OpenBSD.
:
:Unless there are objections, I'll probably commit within the next couple
:of days - I had a couple of questions / notes though particularly
:on the VNIOCGET ioctl kernel code:
It looks great.
:- I'm implicitly trusting the input, assuming that this is
: checked on kernel copy-in time. Is this a correct assumption
: (I didn't have time to track it down)
If I remember right the kernel does the copyin/copyout for ioctl's
for you, so I believe the structure's integrity is good at the
point where you process it. You still have to bounds-check the
parameters of course (and it looks like you do).
Note that the length parameter encoded in the ioctl number
is limited to 8192 bytes (sys/ioccom.h). It can encode
the vn_user structure since PATH_MAX is only 1K, but be aware
of the limit.
:- The 'struct vn_user' doesn't store the vn file path, so I use the
: vfs cache to re-lookup the vnode pointer backing the VN -
: is this silly?
:
: Also, I'm not sure if I needed to lock anything before using
: the vfs cache, so there might be problems there.
I'd suggest just constructing the path by hand and assuming the
form "/dev/vn*". The namecache reference is not guarenteed
to exist... for example, the namecache can get flushed.
:- I've not yet run this under jails, which may mean a path disclosure
: problem. Suggestions on fixing this if it is an issue welcome.
It should theoretically work but if it doesn't it's a problem
with vn_fullpath(). curproc is always valid in the ioctl path so
you don't have to re-roll vn_fullpath(). Though, again, I suggest
just constructing the path manually and not using the namecache at all.
:- I wasn't quite sure on how to do the swap size calculation for swap
: backed vns in some cases & got bored at that point. Should work for
: the normal case. Yea, lame excuse, I know.
:
:Tested briefly on a vmware UP VM & vkernel so far.
:
:Next up: Add a mount_vnd interface to vnconfig, after which it
:might make sense to move this piece into /usr/src/sbin
:instead of usr.sbin.
/sbin is probably better then /usr/sbin, yah.
-Matt
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