memshrtool is a tool for a human to use, rather than a test. Move it into
misc/ as a more appropriate location to live. Also rename it to
xen-memshare
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
xen-access is a tool for a human to use, rather than a test. Move it
into misc/ as a more appropriate location to live.
Move the -DXC_WANT_COMPAT_DEVICEMODEL_API from CFLAGS into xen-access.c itself
to avoid adding Makefile complexity.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Tamas K Lengyel <tamas@tklengyel.com>
The python unit tests were dropped in Xen 4.12 due to being obsolete, but the
scripts to run the tests were missed. Clean up .gitignore as well.
Also drop the libxenctrl {C,LD}FLAGS adjustments in the Makefile. This logic
isn't used, and isn't appropriate even in principle, as there are tests in
here which don't want to use libxenctrl.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Just code movement as a preparatory change before xg_sr_* will be moved.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
When device is removed, backend domain (which may be a driver domain) is
responsible for removing backend entries from xenstore. But in case of
driver domain, it has no access to remove all of them - specifically the
directory named after frontend-id remains. This may accumulate enough to
exceed xenstore quote of the driver domain, breaking further devices.
Fix this by calling libxl__xs_path_cleanup() on the backend path from
libxl__device_destroy() in the toolstack domain too. Note
libxl__device_destroy() is called when the driver domain already removed
what it can (see device_destroy_be_watch_cb()->device_hotplug_done()).
Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Acked-by: Wei Liu <wl@xen.org>
Update to v1.21.1 to fix build in Tumbleweed, which has been broken
since months due to lack of new release.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Wei Liu <wl@xen.org>
The FreeBSD ioctls have the same fields has the Linux ones, so the
same file can be shared between both OSes.
No functional change for OSes different than FreeBSD.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Wei Liu <wl@xen.org>
Implement restrict, map resource and unmap resource helpers on
FreeBSD.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Wei Liu <wl@xen.org>
domain->remote_port and restore_existing_connections() are useless and
can be removed.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
set_tdb_key() can be used by destroy_node(), too. So remove the static
attribute and move it to xenstored_core.c.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Paul Durrant <paul@xen.org>
When xenstored crashes due to an unrecoverable condition it is calling
either barf() or barf_perror() to issue a message and then exit().
Make sure the message is visible somewhere by using syslog()
additionally to xprintf(), as the latter will be visible only with
tracing active.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Reviewed-by: Julien Grall <jgrall@amazon.com>
This patch reverts eight patches from staging.
The offending patch is the one that introduced libxl_pci_bdf (last one
in the list). The rest depend on that patch so they are also reverted.
8bf0fab142 "libxl / libxlu: support 'xl pci-attach/detach' by name"
e1141654c3 "docs/man: modify xl-pci-configuration(5) to add 'name' field to PCI_SPEC_STRING"
93c16ae47b "xl: support naming of assignable devices"
5ab684cb3e "libxl: introduce libxl_pci_bdf_assignable_add/remove/list/list_free(), ..."
66c2fbc6e8 "libxl: convert internal functions in libxl_pci.c..."
f73c5dd56d "docs/man: modify xl(1) in preparation for naming of assignable devices"
96ed6ff297 "libxlu: introduce xlu_pci_parse_spec_string()"
929f231140 "libxl: introduce 'libxl_pci_bdf' in the idl..."
Signed-off-by: Wei Liu <wl@xen.org>
This patch adds a 'name' field into the idl for 'libxl_device_pci' and
libxlu_pci_parse_spec_string() is modified to parse the new 'name'
parameter of PCI_SPEC_STRING detailed in the updated documention in
xl-pci-configuration(5).
If the 'name' field is non-NULL then both libxl_device_pci_add() and
libxl_device_pci_remove() will use it to look up the device BDF in
the list of assignable devices.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Acked-by: Wei Liu <wl@xen.org>
This patch converts libxl to use libxl_pci_bdf_assignable_add/remove/list/
list_free() rather than libxl_device_pci_assignable_add/remove/list/
list_free(), which then allows naming of assignable devices to be supported.
With this patch applied 'xl pci-assignable-add' will take an optional '--name'
parameter, 'xl pci-assignable-remove' can be passed either a BDF or a name and
'xl pci-assignable-list' will take a optional '--show-names' flag which
determines whether names are displayed in its output.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Acked-by: Wei Liu <wl@xen.org>
which support naming and use 'libxl_pci_bdf' rather than 'libxl_device_pci',
as replacements for libxl_device_pci_assignable_add/remove/list/list_free().
libxl_pci_bdf_assignable_add() takes a 'name' parameter which is stored in
xenstore and facilitates two addtional functions added by this patch:
libxl_pci_bdf_assignable_name2bdf() and libxl_pci_bdf_assignable_bdf2name().
Currently there are no callers of these two functions. They will be added in
a subsequent patch.
libxl_device_pci_assignable_add/remove/list/list_free() are left in place
for compatibility but are re-implemented in terms of the newly introduced
functions.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Acked-by: Wei Liu <wl@xen.org>
This patch largely re-writes the code to parse a PCI_SPEC_STRING and enters
it via the newly introduced function. The new parser also deals with 'bdf'
and 'vslot' as non-positional paramaters, as per the documentation in
xl-pci-configuration(5).
The existing xlu_pci_parse_bdf() function remains, but now strictly parses
BDF values. Some existing callers of xlu_pci_parse_bdf() are
modified to call xlu_pci_parse_spec_string() as per the documentation in xl(1).
NOTE: Usage text in xl_cmdtable.c and error messages are also modified
appropriately.
As a side-effect this patch also fixes a bug where using '*' to specify
all functions would lead to an assertion failure at the end of
xlu_pci_parse_bdf().
Fixes: d25cc3ec93 ("libxl: workaround gcc 10.2 maybe-uninitialized warning")
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Acked-by: Wei Liu <wl@xen.org>
... and use in 'libxl_device_pci'
This patch is preparatory work for restricting the type passed to functions
that only require BDF information, rather than passing a 'libxl_device_pci'
structure which is only partially filled. In this patch only the minimal
mechanical changes necessary to deal with the structural changes are made.
Subsequent patches will adjust the code to make better use of the new type.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Acked-by: Wei Liu <wl@xen.org>
Acked-by: Nick Rosbrook <rosbrookn@ainfosec.com>
... rather than an open-coded equivalent.
This patch tidies up the is_pci_in_array() function, making it take a single
'libxl_device_pci' argument rather than separate domain, bus, device and
function arguments. The already-available COMPARE_PCI() macro can then be
used and it is also modified to return 'bool' rather than 'int'.
The patch also modifies libxl_pci_assignable() to use is_pci_in_array() rather
than a separate open-coded equivalent, and also modifies it to return a
'bool' rather than an 'int'.
NOTE: The COMPARE_PCI() macro is also fixed to include the 'domain' in its
comparison, which should always have been the case.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Acked-by: Wei Liu <wl@xen.org>
... to be used by callers of libxl_device_pci_assignable_list().
Currently there is no API for callers of libxl_device_pci_assignable_list()
to free the list. The xl function pciassignable_list() calls
libxl_device_pci_dispose() on each element of the returned list, but
libxl_pci_assignable() in libxl_pci.c does not. Neither does the implementation
of libxl_device_pci_assignable_list() call libxl_device_pci_init().
This patch adds the new API function, makes sure it is used everywhere and
also modifies libxl_device_pci_assignable_list() to initialize list
entries rather than just zeroing them.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Acked-by: Wei Liu <wl@xen.org>
A previous patch introduced libxl_device_pci_list_free() which should be used
by callers of libxl_device_pci_list() to properly dispose of the exported
'libxl_device_pci' types and the free the memory holding them. Whilst all
current callers do ensure the memory is freed, only the code in xl's
pcilist() function actually calls libxl_device_pci_dispose(). As it stands
this laxity does not lead to any memory leaks, but the simple addition of
.e.g. a 'string' into the idl definition of 'libxl_device_pci' would lead
to leaks.
This patch makes sure all callers of libxl_device_pci_list() can call
libxl_device_pci_list_free() by keeping copies of 'libxl_device_pci'
structures inline in 'pci_add_state' and 'pci_remove_state' (and also making
sure these are properly disposed at the end of the operations) rather
than keeping pointers to the structures returned by libxl_device_pci_list().
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Acked-by: Wei Liu <wl@xen.org>
Use of this function is a very inefficient way to check whether a device
has already been assigned.
This patch adds code that saves the domain id in xenstore at the point of
assignment, and removes it again when the device id de-assigned (or the
domain is destroyed). It is then straightforward to check whether a device
has been assigned by checking whether a device has a saved domain id.
NOTE: To facilitate the xenstore check it is necessary to move the
pci_info_xs_read() earlier in libxl_pci.c. To keep related functions
together, the rest of the pci_info_xs_XXX() functions are moved too.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Acked-by: Wei Liu <wl@xen.org>
The code currently checks explicitly whether the device is already assigned,
but this is actually unnecessary as assigned devices do not form part of
the list returned by libxl_device_pci_assignable_list() and hence the
libxl_pci_assignable() test would have already failed.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Acked-by: Wei Liu <wl@xen.org>
For the purposes of re-binding a device to its previous driver
libxl__device_pci_assignable_add() writes the driver path into xenstore.
This path is then read back in libxl__device_pci_assignable_remove().
The functions that support this writing to and reading from xenstore are
currently dedicated for this purpose and hence the node name 'driver_path'
is hard-coded. This patch generalizes these utility functions and passes
'driver_path' as an argument. Subsequent patches will invoke them to
access other nodes.
NOTE: Because functions will have a broader use (other than storing a
driver path in lieu of pciback) the base xenstore path is also
changed from '/libxl/pciback' to '/libxl/pci'.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Acked-by: Wei Liu <wl@xen.org>
... to hold a pointer to the device.
There is already a 'pci' field in 'pci_add_state' so simply use that from
the start. This also allows the 'pci' (#3) argument to be dropped from
do_pci_add().
NOTE: This patch also changes the type of the 'pci_domid' field in
'pci_add_state' from 'int' to 'libxl_domid' which is more appropriate
given what the field is used for.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Acked-by: Wei Liu <wl@xen.org>
Both 'domid' and 'pci' are available in 'pci_remove_state' so there is no
need to also pass them as separate arguments.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Acked-by: Wei Liu <wl@xen.org>
Other parameters, such as 'msitranslate' and 'permissive' are dealt with
but 'rdm_policy' appears to be have been completely missed.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Acked-by: Wei Liu <wl@xen.org>
Currently libxl__device_pci_add_xenstore() is broken in that does not
update the domain's configuration for the first device added (which causes
creation of the overall backend area in xenstore). This can be easily observed
by running 'xl list -l' after adding a single device: the device will be
missing.
This patch fixes the problem and adds a DEBUG log line to allow easy
verification that the domain configuration is being modified. Also, the use
of libxl__device_generic_add() is dropped as it leads to a confusing situation
where only partial backend information is written under the xenstore
'/libxl' path. For LIBXL__DEVICE_KIND_PCI devices the only definitive
information in xenstore is under '/local/domain/0/backend' (the '0' being
hard-coded).
NOTE: This patch includes a whitespace in add_pcis_done().
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Acked-by: Wei Liu <wl@xen.org>
... devices.
Currently there is an assumption built into libxl__device_list() that device
backends are fully enumarated under the '/libxl' path in xenstore. This is
not the case for PCI backend devices, which are only properly enumerated
under '/local/domain/0/backend'.
This patch adds a new get_path() method to libxl__device_type to allow a
backend implementation (such as PCI) to specify the xenstore path where
devices are enumerated and modifies libxl__device_list() to use this method
if it is available. Also, if the get_num() method is defined then the
from_xenstore() method expects to be passed the backend path without the device
number concatenated, so this issue is also rectified.
Having made libxl__device_list() work correctly, this patch removes the
open-coded libxl_pci_device_pci_list() in favour of an evaluation of the
LIBXL_DEFINE_DEVICE_LIST() macro. This has the side-effect of also defining
libxl_pci_device_pci_list_free() which will be used in subsequent patches.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Acked-by: Wei Liu <wl@xen.org>
To improve naming consistency, replaces occurrences of 'pcidev' with 'pci'.
The only remaining use of the term should be in relation to
'libxl_domain_config' where there are fields named 'pcidevs' and 'num_pcidevs'.
Purely cosmetic. No functional change.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Acked-by: Wei Liu <wl@xen.org>
The seemingly arbitrary use of 'pci' and 'pcidev' in the code in libxl_pci.c
is confusing and also compromises use of some macros used for other device
types. Indeed it seems that DEFINE_DEVICE_TYPE_STRUCT_X exists solely because
of this duality.
This patch purges use of 'pcidev' from the libxl internal code, but
unfortunately the 'pcidevs' and 'num_pcidevs' fields in 'libxl_domain_config'
are part of the API and need to be retained to avoid breaking callers,
particularly libvirt.
DEFINE_DEVICE_TYPE_STRUCT_X is still removed to avoid the special case in
libxl_pci.c but DEFINE_DEVICE_TYPE_STRUCT is given an extra 'array' argument
which is used to identify the fields in 'libxl_domain_config' relating to
the device type.
NOTE: Some of the more gross formatting errors (such as lack of spaces after
keywords) that came into context have been fixed in libxl_pci.c.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Acked-by: Wei Liu <wl@xen.org>
There are no users left, xenpaging has its own variant.
The last user was removed with commit 11d0044a16
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Wei Liu <wl@xen.org>
Allocate enough memory so that the returned pointer can be safely
accessed as an array of unsigned long.
The actual bitmap size in units of bytes, as returned by bitmap_size,
remains unchanged.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Wei Liu <wl@xen.org>
The different fixed limits for absolute and relative path lengths of
Xenstore nodes make it possible to create per-domain nodes via
absolute paths which are not accessible using relative paths, as the
two limits differ by 1024 characters.
Instead of this weird limits use only one limit, which applies to the
relative path length of per-domain nodes and to the absolute path
length of all other nodes. This means, the path length check is
applied to the path after removing a possible start of
"/local/domain/<n>/" with <n> being a domain id.
There has been the request to be able to limit the path lengths even
more, so an additional quota is added which can be applied to path
lengths. It is XENSTORE_REL_PATH_MAX (2048) per default, but can be
set to lower values. This is done via the new "-M" or "--path-max"
option when invoking xenstored.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Acked-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Wei Liu <wl@xen.org>
c/s f8c72b5261 "oxenstored: implement XS_RESET_WATCHES" from Xen 4.6
introduced reset watches support in oxenstored by mirroring the change
in cxenstored.
However the OCaml version has some additional data structures to
optimize watch firing, and just resetting the watches in one of the data
structures creates a security bug where a malicious guest kernel can
exceed its watch quota, driving oxenstored into OOM:
* create watches
* reset watches (this still keeps the watches lingering in another data
structure, using memory)
* create some more watches
* loop until oxenstored dies
The guest kernel doesn't necessarily have to be malicious to trigger
this:
* if control/platform-feature-xs_reset_watches is set
* the guest kexecs (e.g. because it crashes)
* on boot more watches are set up
* this will slowly "leak" memory for watches in oxenstored, driving it
towards OOM.
This is XSA-330.
Fixes: f8c72b5261 ("oxenstored: implement XS_RESET_WATCHES")
Signed-off-by: Edwin Török <edvin.torok@citrix.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
XenStored will kill any connection that it thinks has misbehaved,
this is currently happening in two places:
* In `handle_input()` if the sanity check on the ring and the message
fails.
* In `handle_output()` when failing to write the response in the ring.
As the domain structure is a child of the connection, XenStored will
destroy its view of the domain when killing the connection. This will
result in sending @releaseDomain event to all the watchers.
As the watch event doesn't carry which domain has been released,
the watcher (such as XenStored) will generally go through the list of
domains registers and check if one of them is shutting down/dying.
In the case of a client misbehaving, the domain will likely to be
running, so no action will be performed.
When the domain is effectively destroyed, XenStored will not be aware of
the domain anymore. So the watch event is not going to be sent.
By consequence, the watchers of the event will not release mappings
they may have on the domain. This will result in a zombie domain.
In order to send @releaseDomain event at the correct time, we want
to keep the domain structure until the domain is effectively
shutting-down/dying.
We also want to keep the connection around so we could possibly revive
the connection in the future.
A new flag 'is_ignored' is added to mark whether a connection should be
ignored when checking if there are work to do. Additionally any
transactions, watches, buffers associated to the connection will be
freed as you can't do much with them (restarting the connection will
likely need a reset).
As a side note, when the device model were running in a stubdomain, a
guest would have been able to introduce a use-after-free because there
is two parents for a guest connection.
This is XSA-325.
Reported-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
Signed-off-by: Harsha Shamsundara Havanur <havanur@amazon.com>
Signed-off-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Paul Durrant <paul@xen.org>
By setting a watch with a very large tag it is possible to trick
xenstored to send watch event messages exceeding the maximum allowed
payload size. This might in turn lead to a crash of xenstored as the
resulting error can cause dereferencing a NULL pointer in case there
is no active request being handled by the guest the watch event is
being sent to.
Fix that by just dropping such watch events. Additionally modify the
error handling to test the pointer to be not NULL before dereferencing
it.
This is XSA-324.
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Julien Grall <jgrall@amazon.com>
Currently, oxenstored checks the length of paths against 1024, then
prepends "/local/domain/$DOMID/" to relative paths. This allows a domU
to create paths which can't subsequently be read by anyone, even dom0.
This also interferes with listing directories, etc.
Define a new oxenstored.conf entry: quota-path-max, defaulting to 1024
as before. For paths that begin with "/local/domain/$DOMID/" check the
relative path length against this quota. For all other paths check the
entire path length.
This ensures that if the domid changes (and thus the length of a prefix
changes) a path that used to be valid stays valid (e.g. after a
live-migration). It also ensures that regardless how the client tries
to access a path (domid-relative or absolute) it will get consistent
results, since the limit is always applied on the final canonicalized
path.
Delete the unused Domain.get_path to avoid it being confused with
Connection.get_path (which differs by a trailing slash only).
Rewrite Util.path_validate to apply the appropriate length restriction
based on whether the path is relative or not. Remove the check for
connection_path being absolute, because it is not guest controlled data.
This is part of XSA-323.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Edwin Török <edvin.torok@citrix.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
domain ids are prone to wrapping (15-bits), and with sufficient number
of VMs in a reboot loop it is possible to trigger it. Xenstore entries
may linger after a domain dies, until a toolstack cleans it up. During
this time there is a window where a wrapped domid could access these
xenstore keys (that belonged to another VM).
To prevent this do a cleanup when a domain dies:
* walk the entire xenstore tree and update permissions for all nodes
* if the dead domain had an ACL entry: remove it
* if the dead domain was the owner: change the owner to Dom0
This is done without quota checks or a transaction. Quota checks would
be a no-op (either the domain is dead, or it is Dom0 where they are not
enforced). Transactions are not needed, because this is all done
atomically by oxenstored's single thread.
The xenstore entries owned by the dead domain are not deleted, because
that could confuse a toolstack / backends that are still bound to it
(or generate unexpected watch events). It is the responsibility of a
toolstack to remove the xenstore entries themselves.
This is part of XSA-322.
Signed-off-by: Edwin Török <edvin.torok@citrix.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
Access rights of Xenstore nodes are per domid. Unfortunately existing
granted access rights are not removed when a domain is being destroyed.
This means that a new domain created with the same domid will inherit
the access rights to Xenstore nodes from the previous domain(s) with
the same domid.
This can be avoided by adding a generation counter to each domain.
The generation counter of the domain is set to the global generation
counter when a domain structure is being allocated. When reading or
writing a node all permissions of domains which are younger than the
node itself are dropped. This is done by flagging the related entry
as invalid in order to avoid modifying permissions in a way the user
could detect.
A special case has to be considered: for a new domain the first
Xenstore entries are already written before the domain is officially
introduced in Xenstore. In order not to drop the permissions for the
new domain a domain struct is allocated even before introduction if
the hypervisor is aware of the domain. This requires adding another
bool "introduced" to struct domain in xenstored. In order to avoid
additional padding holes convert the shutdown flag to bool, too.
As verifying permissions has its price regarding runtime add a new
quota for limiting the number of permissions an unprivileged domain
can set for a node. The default for that new quota is 5.
This is part of XSA-322.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Acked-by: Julien Grall <julien@amazon.com>
There are flags to turn off quotas and the permission system, so add one
that turns off the newly introduced watch permission checks as well.
This is part of XSA-115.
Signed-off-by: Edwin Török <edvin.torok@citrix.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Today watch events are sent regardless of the access rights of the
node the event is sent for. This enables any guest to e.g. setup a
watch for "/" in order to have a detailed record of all Xenstore
modifications.
Modify that by sending only watch events for nodes that the watcher
has a chance to see otherwise (either via direct reads or by querying
the children of a node). This includes cases where the visibility of
a node for a watcher is changing (permissions being removed).
Permissions for nodes are looked up either in the old (pre
transaction/command) or current trees (post transaction). If
permissions are changed multiple times in a transaction only the final
version is checked, because considering a transaction atomic the
individual permission changes would not be noticable to an outside
observer.
Two trees are only needed for set_perms: here we can either notice the
node disappearing (if we loose permission), appearing
(if we gain permission), or changing (if we preserve permission).
RM needs to only look at the old tree: in the new tree the node would be
gone, or could have different permissions if it was recreated (the
recreation would get its own watch fired).
Inside a tree we lookup the watch path's parent, and then the watch path
child itself. This gets us 4 sets of permissions in worst case, and if
either of these allows a watch, then we permit it to fire. The
permission lookups are done without logging the failures, otherwise we'd
get confusing errors about permission denied for some paths, but a watch
still firing. The actual result is logged in xenstored-access log:
'w event ...' as usual if watch was fired
'w notfired...' if the watch was not fired, together with path and
permission set to help in troubleshooting
Adding a watch bypasses permission checks and always fires the watch
once immediately. This is consistent with the specification, and no
information is gained (the watch is fired both if the path exists or
doesn't, and both if you have or don't have access, i.e. it reflects the
path a domain gave it back to that domain).
There are some semantic changes here:
* Write+rm in a single transaction of the same path is unobservable
now via watches: both before and after a transaction the path
doesn't exist, thus both tree lookups come up with the empty
permission set, and noone, not even Dom0 can see this. This is
consistent with transaction atomicity though.
* Similar to above if we temporarily grant and then revoke permission
on a path any watches fired inbetween are ignored as well
* There is a new log event (w notfired) which shows the permission set
of the path, and the path.
* Watches on paths that a domain doesn't have access to are now not
seen, which is the purpose of the security fix.
This is part of XSA-115.
Signed-off-by: Edwin Török <edvin.torok@citrix.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
The special watches "@introduceDomain" and "@releaseDomain" should be
allowed for privileged callers only, as they allow to gain information
about presence of other guests on the host. So send watch events for
those watches via privileged connections only.
Start to address this by treating the special watches as regular nodes
in the tree, which gives them normal semantics for permissions. A later
change will restrict the handling, so that they can't be listed, etc.
This is part of XSA-115.
Signed-off-by: Edwin Török <edvin.torok@citrix.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
This will make it easier insert additional checks in a follow-up patch.
All watches are now fired from a single function.
This is part of XSA-115.
Signed-off-by: Edwin Török <edvin.torok@citrix.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Andrew Cooper