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* xen/xenbus: Reject replies with payload > XENSTORE_PAYLOAD_MAX.Ian Campbell2012-01-251-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 9e7860cee18241633eddb36a4c34c7b61d8cecbc upstream. Haogang Chen found out that: There is a potential integer overflow in process_msg() that could result in cross-domain attack. body = kmalloc(msg->hdr.len + 1, GFP_NOIO | __GFP_HIGH); When a malicious guest passes 0xffffffff in msg->hdr.len, the subsequent call to xb_read() would write to a zero-length buffer. The other end of this connection is always the xenstore backend daemon so there is no guest (malicious or otherwise) which can do this. The xenstore daemon is a trusted component in the system. However this seem like a reasonable robustness improvement so we should have it. And Ian when read the API docs found that: The payload length (len field of the header) is limited to 4096 (XENSTORE_PAYLOAD_MAX) in both directions. If a client exceeds the limit, its xenstored connection will be immediately killed by xenstored, which is usually catastrophic from the client's point of view. Clients (particularly domains, which cannot just reconnect) should avoid this. so this patch checks against that instead. This also avoids a potential integer overflow pointed out by Haogang Chen. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Cc: Haogang Chen <haogangchen@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* Merge branch 'xen/xenbus' into upstream/xenJeremy Fitzhardinge2010-08-041-10/+47
|\ | | | | | | | | | | * xen/xenbus: implement O_NONBLOCK for /proc/xen/xenbus xenbus: do not hold transaction_mutex when returning to userspace
| * xenbus: do not hold transaction_mutex when returning to userspaceIan Campbell2009-11-031-10/+47
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ================================================ [ BUG: lock held when returning to user space! ] ------------------------------------------------ xenstore-list/3522 is leaving the kernel with locks still held! 1 lock held by xenstore-list/3522: #0: (&xs_state.transaction_mutex){......}, at: [<c026dc6f>] xenbus_dev_request_and_reply+0x8f/0xa0 The canonical fix for this type of issue appears to be to maintain a count manually rather than using an rwsem so do that here. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
* | xen: avoid allocation causing potential swap activity on the resume pathIan Campbell2010-06-031-1/+1
|/ | | | | | | | | | | | | | | | | | | Since the device we are resuming could be the device containing the swap device we should ensure that the allocation cannot cause IO. On resume, this path is triggered when the running system tries to continue using its devices. If it cannot then the resume will fail; to try to avoid this we let it dip into the emergency pools. The majority of these changes were made when linux-2.6.18-xen.hg changeset e8b49cfbdac0 was ported upstream in a144ff09bc52ef3f3684ed23eadc9c7c0e57b3aa but somehow this hunk was dropped. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Acked-by: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Stable Kernel <stable@kernel.org> # .32.x
* xen: use device model for suspending xenbus devicesIan Campbell2009-03-301-0/+2
| | | | | Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
* xen: add xenfs to allow usermode <-> Xen interactionAlex Zeffertt2009-01-081-0/+1
| | | | | | | | | | | | | | | The xenfs filesystem exports various interfaces to usermode. Initially this exports a file to allow usermode to interact with xenbus/xenstore. Traditionally this appeared in /proc/xen. Rather than extending procfs, this patch adds a backward-compat mountpoint on /proc/xen, and provides a xenfs filesystem which can be mounted there. Signed-off-by: Alex Zeffertt <alex.zeffertt@eu.citrix.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* xen: Avoid allocations causing swap activity on the resume pathIan Campbell2008-07-031-5/+5
| | | | | | | | | | | | | | | | | | | | Avoid allocations causing swap activity on the resume path by preventing the allocations from doing IO and allowing them to access the emergency pools. These paths are used when a frontend device is trying to connect to its backend driver over Xenbus. These reconnections are triggered on demand by IO, so by definition there is already IO underway, and further IO would naturally deadlock. On resume, this path is triggered when the running system tries to continue using its devices. If it cannot then the resume will fail; to try to avoid this we let it dip into the emergency pools. [ linux-2.6.18-xen changesets e8b49cfbdac, fdb998e79aba ] Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* xenbus_xs.c: fix a use-after-freeAdrian Bunk2007-07-261-1/+1
| | | | | | | | | This patch fixes an obvious use-after-free spotted by the Coverity checker. Signed-off-by: Adrian Bunk <bunk@stusta.de> Acked-by: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* xen: add the Xenbus sysfs and virtual device hotplug driverJeremy Fitzhardinge2007-07-181-0/+861
This communicates with the machine control software via a registry residing in a controlling virtual machine. This allows dynamic creation, destruction and modification of virtual device configurations (network devices, block devices and CPUS, to name some examples). [ Greg, would you mind giving this a review? Thanks -J ] Signed-off-by: Ian Pratt <ian.pratt@xensource.com> Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk> Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: Chris Wright <chrisw@sous-sol.org> Cc: Greg KH <greg@kroah.com>