The remote (hostile) process can set ring buffer indices to any value
at any time. If that happens, it is possible to get "buffer space"
(either for writing data, or ready for reading) negative or greater
than buffer size. This will end up with buffer overflow in the second
memcpy inside of do_send/do_recv.
Fix this by introducing new available bytes accessor functions
raw_get_data_ready and raw_get_buffer_space which are robust against
mad ring states, and only return sanitised values.
Proof sketch of correctness:
Now {rd,wr}_{cons,prod} are only ever used in the raw available bytes
functions, and in do_send and do_recv.
The raw available bytes functions do unsigned arithmetic on the
returned values. If the result is "negative" or too big it will be
>ring_size (since we used unsigned arithmetic). Otherwise the result
is a positive in-range value representing a reasonable ring state, in
which case we can safely convert it to int (as the rest of the code
expects).
do_send and do_recv immediately mask the ring index value with the
ring size. The result is always going to be plausible. If the ring
state has become mad, the worst case is that our behaviour is
inconsistent with the peer's ring pointer. I.e. we read or write to
arguably-incorrect parts of the ring - but always parts of the ring.
And of course if a peer misoperates the ring they can achieve this
effect anyway.
So the security problem is fixed.
This is XSA-86.
(The patch is essentially Ian Jackson's work, although parts of the
commit message are by Marek.)
Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Since the string size is being specified by the guest, we must range
check it properly before doing allocations based on it. While for the
two cases that are exposed only to trusted guests (via policy
restriction) this just uses an arbitrary upper limit (PAGE_SIZE), for
the FLASK_[GS]ETBOOL case (which any guest can use) the upper limit
gets enforced based on the longest name across all boolean settings.
This is XSA-84.
Reported-by: Matthew Daley <mattd@bugfuzz.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
When a timeout has occurred, it is deregistered. However, we failed
to record this fact by updating etime->func. As a result,
libxl__ev_time_isregistered would say `true' for a timeout which has
already happened.
It is necessary to clear etime->func before the callback, because the
callback might want to reinstate the timeout, or might free the etime
(or its containing struct) entirely.
The results are that we might try to have the timeout occur again
(causing problems for the call site), and/or corrupt the timeout list.
This fixes the timedereg event system unit test.
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
Bring together the two places where etime->func() is called into a new
function time_occurs. For one call site this is pure code motion.
For the other the only semantic change is the introduction of a new
debugging message.
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
Test timeout deregistration idempotency. In the current tree this
test fails because ev->func is not cleared, meaning that a timeout
can be removed from the list more than once, corrupting the list.
It is necessary to use multiple timeouts to demonstrate this bug,
because removing the very same entry twice from a list in quick
succession, without modifying the list in other ways in between,
doesn't actually corrupt the list. (Since removing an entry from a
doubly-linked list just copies next and back from the disappearing
entry into its neighbours.)
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
We provide a new LIBXL_TESTS facility in the Makefile.
Also provide some helpful common routines for unit tests to use.
We don't want to put the weird test case entrypoints and the weird
test case code in the main libxl.so library. Symbol hiding prevents
us from simply directly linking the libxl_test_FOO.o in later. So
instead we provide a special library libxenlight_test.so which is used
only locally.
There are not yet any test cases defined; that will come in the next
patch.
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
Use the new libxl__pipe_nonblock and _close functions, rather than
open coding the same logic. Now the pipe is nonblocking, which avoids
a race which could result in libxl deadlocking in a multithreaded
program.
Reported-by: Jim Fehlig <jfehlig@suse.com>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Break out the pipe creation and destruction from the poller code
into two new functions libxl__pipe_nonblock and libxl__pipe_close.
Also change direct use of pipe() to libxl_pipe.
No overall functional difference other than minor differences in exact
log messages.
Also move libxl__self_pipe_wakeup and libxl__self_pipe_eatall into the
new pipe utilities section in libxl_event.c; this is pure code motion.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
--
v3: Mention that we switched pipe() -> libxl_pipe()
Previously, an application which had multiple libxl ctxs in multiple
threads, would have to itself plumb SIGCHLD through to each ctx.
Instead, permit multiple libxl ctxs to all share the SIGCHLD handler.
We keep a list of all the ctxs which are interested in SIGCHLD and
notify all of their self-pipes.
In more detail:
* sigchld_owner, the ctx* of the SIGCHLD owner, is replaced by
sigchld_users, a list of SIGCHLD users.
* Each ctx keeps track of whether it is on the users list, so that
libxl__sigchld_needed and libxl__sigchld_notneeded now instead of
idempotently installing and removing the handler, idempotently add
or remove the ctx from the list.
We ensure that we always have the SIGCHLD handler installed
iff the sigchld_users list is nonempty. To make this a bit
easier we make sigchld_installhandler_core and
sigchld_removehandler_core idempotent.
Specifically, the call sites for sigchld_installhandler_core and
sigchld_removehandler_core are updated to manipulate sigchld_users
and only call the install or remove functions as applicable.
* In the signal handler we walk the list of SIGCHLD users and write
to each of their self-pipes. That means that we need to arrange to
defer SIGCHLD when we are manipulating the list (to avoid the
signal handler interrupting our list manipulation); this is quite
tiresome to arrange.
The code as written will, on the first installation of the SIGCHLD
handler, firstly install the real handler, then immediately replace
it with the deferral handler. Doing it this way makes the code
clearer as it makes the SIGCHLD deferral machinery much more
self-contained (and hence easier to reason about).
* The first part of libxl__sigchld_notneeded is broken out into a new
function sigchld_user_remove (which is also needed during for
postfork). And of course that first part of the function is now
rather different, as explained above.
* sigchld_installhandler_core no longer takes the gc argument,
because it now deals with SIGCHLD for all ctxs.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
---
v3: Include bugfixes from "Fixup SIGCHLD sharing" patch:
* Use a mutex for defer_sigchld, to guard against concurrency
between the thread calling defer_sigchld and an instance of the
primary signal handler on another thread.
* libxl_sigchld_owner_libxl_always is incompatible with SIGCHLD
sharing. Document this correctly.
Fix "have have" error in comment.
Move removal of newly unused variables to previous patch.
v2.1: Provide feature test macro LIBXL_HAVE_SIGCHLD_SHARING
We are going to want introduce another call site in the final
substantive patch.
Pure code motion; no functional change.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
---
v3: Remove now-unused variables from sigchld_installhandler_core
We are going to change these functions so that different libxl ctx's
can share a single SIGCHLD handler. Rename them now to a new name
which doesn't imply unconditional handler installation or removal.
Also note in the comments that they are idempotent.
No functional change.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
This is the feature test macro for libxl_childproc_sigchld_occurred
and libxl_sigchld_owner_libxl_always_selective_reap.
It is split out into this separate patch because: a single feature
test is sensible because we do not intend anyone to release or ship
libxl versions with one of these but not the other; but, the two
features are in separate patches for clarity; and, this just makes
reading the actual code easier.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
Applications exist which want to use libxl in an event-driven mode but
which do not integrate child termination into their event system, but
instead reap all their own children synchronously.
In such an application libxl must own SIGCHLD but avoid reaping any
children that don't belong to libxl.
Provide libxl_sigchld_owner_libxl_always_selective_reap which has this
behaviour.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
---
v2: Document the new mode in the big "Subprocess handling" comment.
Applications exist which don't keep track of all their child processes
in a manner suitable for coherent dispatch of their termination. In
such a situation, nothing in the whole process may call wait, or
waitpid(-1,,). Doing so reaps processes belonging to other parts of
the application and there is then no way to deliver the exit status to
the right place.
To facilitate this, provide a facility for such an application to ask
libxl to call waitpid on each of its children individually.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
libxl_sigchld_owner_libxl ought to have been mentioned in the list of
options for chldowner. Since it's the default, move the description
of the its behaviour into the description of that option.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
Clarify that libxl_sigchld_owner_libxl causes libxl to reap all the
process's children, and clarify the wording of the description of
libxl_sigchld_owner_libxl_always.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
This is a simple error-handling wrapper for waitpid. We're going to
want to call waitpid somewhere else and this avoids some of the
duplication.
No functional change in this patch. (Technically, we used to check
chldmode_ours again in the EINTR case, and don't now, but that can't
have changed because we continuously hold the libxl ctx lock.)
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
There have been ABI/API changes in libxc. Bump its MAJOR (which
affets libxenguest et al too.)
There have been ABI changes in libxl. Bump its MAJOR.
(The API changes have been dealt with as we go along - there is
already a LIBXL_API_VERSION 0x040400.)
None of the other libraries have changed their interfaces. I have
verified this by building the tools and searching the dist/install
tree for files matching *.so.*. For each library that showed up, I
did this:
git-diff RELEASE-4.3.0..staging -- `find tools/FOO/ -name \*.h`
where FOO is the corresponding source directory.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
The function domain_page_map_to_mfn can be used to translate a virtual
address mapped by both map_domain_page and map_domain_page_global.
The former is using vmap to map the mfn, therefore domain_page_map_to_mfn
will always fail because the address is not in DOMHEAP range.
Check if the address is in vmap range and use __pa to translate it.
This patch fix guest shutdown when the event fifo is used.
Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Cc: George Dunlap <george.dunlap@citrix.com>
The variable 'rc' is set to 1 at the top of xc_domain_restore, and for the
most part is left alone until success, at which point it is set to 0.
There is a separate 'frc' which for the most part is used to check function
calls, keeping errors separate from 'rc'.
For a toolstack which sets callbacks->toolstack_restore(), and the function
returns 0, any subsequent error will end up with code flow going to "out;",
resulting in the migration being declared a success.
For consistency, update the callsites of xc_dom_gnttab{,_hvm}_seed() to use
'frc', even though their use of 'rc' is currently safe.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
CC: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: George Dunlap <george.dunlap@eu.citrix.com>
It is the compatible string which matters, not the absolute path, and in any
case /chosen/module@N is more often used than /chosen/modules/module@N.
Reported-by: Fu Wei <fu.wei@linaro.org>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Julien Grall <julien.gral@linaro.org>
This patch adds VFP save/restore support form arm64 across context switch.
Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
Signed-off-by: Anup Patel <anup.patel@linaro.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
[ ijc -- dropped now obsolete TODO comments ]
This patch removes reading reset specific values (address, size and mask) from
dts and uses values defined in the code now. This is because currently xgene
reset driver (submitted in linux) is going through a change (which is not yet
accepted), this new driver has a new type of dts bindings for reset. Hence
till linux driver comes to some conclusion, we will use hardcoded values
instead of reading from dts so that xen code will not break due to the linux
transition.
Ref:
http://lists.xen.org/archives/html/xen-devel/2014-01/msg02256.htmlhttp://www.gossamer-threads.com/lists/linux/kernel/1845585
Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
Signed-off-by: Anup Patel <anup.patel@linaro.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
vcpu-set will try to use the HVM path (through QEMU) instead of the PV
path (through xenstore) for a PV guest, if there is a QEMU running for
this domain. This patch check which kind of guest is running before
before doing any call.
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
"Base" context reads already paused the subject vCPU when being the
current one, but that special case isn't being properly dealt with
anyway (at the very least when x86's fsgsbase feature is in use), so
just disallow it.
"Extended" context reads so far didn't do any pausing.
While we can't avoid the reported data being stale by the time it
arrives at the caller, this way we at least guarantee that it is
consistent.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Keir Fraser <keir@xen.org>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Release-acked-by: George Dunlap <george.dunlap@eu.citrix.com>
This is not just for consistency with "base" context updates, but
actually needed so that guest side accesses can't race with control
domain side updates.
This would have been a security issue if XSA-77 hadn't waived them on
the affected domctl operation.
While looking at the code I also spotted a redundant NULL check in the
"base" context update handling code, which is being removed.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Keir Fraser <keir@xen.org>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Release-acked-by: George Dunlap <george.dunlap@eu.citrix.com>
In that case, due to the respective instructions not being privileged,
we can't rely on our in-memory data to always be correct: While the
guest is running, it may change without us knowing about it. Therefore
we need to
- read the correct values from hardware during context switch out
(save_segments())
- read the correct values from hardware during RDMSR emulation
- update in-memory values during guest mode change
(toggle_guest_mode())
For completeness/consistency, WRMSR emulation is also being switched
to use wr[fg]sbase().
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Keir Fraser <keir@xen.org>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Release-acked-by: George Dunlap <george.dunlap@eu.citrix.com>
ARM does not implemented PoD and so returns ENOSYS from XENMEM_set_pod_target.
The correct solution here would be to check for ENOSYS in libxl, unfortunately
xc_domain_set_pod_target suffers from the same broken error reporting as the
rest of libxc and throws away the errno.
So for now conditionally define xc_domain_set_pod_target to return success
(which is what PoD does if nothing needs doing). xc_domain_get_pod_target sets
errno==-1 and returns -1, which matches the broken error reporting of the
existing function. It appears to have no in tree callers in any case.
The conditional should be removed once libxc has been fixed.
This makes ballooning (xl mem-set) work for ARM domains.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Julien Grall <julien.grall@linaro.org>
Cc: george.dunlap@citrix.com
find_next_bit takes a "const unsigned long *" but forcing a cast of an
"uint32_t *" throws away the alignment constraints and ends up causing an
alignment fault on arm64 if the input happened to be 4 but not 8 byte aligned.
Instead of casting use a temporary variable of the right type.
I've had a look around for similar constructs and the only thing I found was
maintenance_interrupt which cases a uint64_t down to an unsigned long, which
although perhaps not best advised is safe I think.
This was observed with the AArch64 Linaro toolchain 2013.12 but I think that
is just coincidental due to subtle changes to the stack layout etc.
Reported-by: Fu Wei <fu.wei@linaro.org>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Julien Grall <julien.grall@linaro.org>
The current implementation of alloc_domain_struct, dereference the newly
allocated pointer even if the allocation has failed.
Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
The original code is wrong because:
* claim mode wants to know the total number of pages needed while
original code provides the additional number of pages needed.
* if pod is enabled memory will already be allocated by the time we try
to claim memory.
So the fix would be:
* move claim mode before actual memory allocation.
* pass the right number of pages to hypervisor.
The "right number of pages" should be number of pages of target memory
minus VGA_HOLE_SIZE, regardless of whether PoD is enabled.
This fixes bug #32.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: George Dunlap <george.dunlap@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Both of these "goto finish;" statements are actually errors, and need to "goto
out;" instead, which will correctly destroy the domain and return an error,
rather than trying to finish the migration (and in at least one scenario,
return success).
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
CC: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: George Dunlap <george.dunlap@eu.citrix.com>
What started out as a simple cleanup patch (eliminating the redundant
check of domctl->cmd before setting "copyback", which as a result
turned the "ext_vcpucontext_out" label useless) revealed a bug in the
handling of XEN_DOMCTL_set_ext_vcpucontext.
Fix this, retaining the cleanup, and at once dropping a stale comment
and an accompanying formatting issue.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Also fix the name of the discard-alignment property, add the missing 'n'.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Keir Fraser <keir@xen.org>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
"ret", being set to -1 early on, gets cleared by the first invocation
of lz4_decompress()/lz4_decompress_unknownoutputsize(), and hence
subsequent failures wouldn't be noticed by the caller without setting
it back to -1 right after those calls.
Linux commit: 2a1d689c9ba42a6066540fb221b6ecbd6298b728
Reported-by: Matthew Daley <mattjd@gmail.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Marek Marczykowski-Górecki