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doc/website/static/security/patches/SA-21:02/xenoom.12.patch
Gordon Tetlow 9030a72250 Add EN-21:01 to EN-21:05, SA-21:01, and SA-21:02. 
Approved by:	so
2021-01-28 18:17:45 -08:00

300 lines
9.6 KiB
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--- sys/dev/xen/balloon/balloon.c.orig
+++ sys/dev/xen/balloon/balloon.c
@@ -310,7 +310,8 @@
static struct xs_watch target_watch =
{
- .node = "memory/target"
+ .node = "memory/target",
+ .max_pending = 1,
};
/* React to a change in the target key */
--- sys/dev/xen/blkback/blkback.c.orig
+++ sys/dev/xen/blkback/blkback.c
@@ -3768,6 +3768,12 @@
xbb->hotplug_watch.callback = xbb_attach_disk;
KASSERT(xbb->hotplug_watch.node == NULL, ("watch node already setup"));
xbb->hotplug_watch.node = strdup(sbuf_data(watch_path), M_XENBLOCKBACK);
+ /*
+ * We don't care about the path updated, just about the value changes
+ * on that single node, hence there's no need to queue more that one
+ * event.
+ */
+ xbb->hotplug_watch.max_pending = 1;
sbuf_delete(watch_path);
error = xs_register_watch(&xbb->hotplug_watch);
if (error != 0) {
--- sys/dev/xen/control/control.c.orig
+++ sys/dev/xen/control/control.c
@@ -432,6 +432,12 @@
xctrl->xctrl_watch.node = "control/shutdown";
xctrl->xctrl_watch.callback = xctrl_on_watch_event;
xctrl->xctrl_watch.callback_data = (uintptr_t)xctrl;
+ /*
+ * We don't care about the path updated, just about the value changes
+ * on that single node, hence there's no need to queue more that one
+ * event.
+ */
+ xctrl->xctrl_watch.max_pending = 1;
xs_register_watch(&xctrl->xctrl_watch);
if (xen_pv_domain())
--- sys/dev/xen/xenstore/xenstore.c.orig
+++ sys/dev/xen/xenstore/xenstore.c
@@ -656,12 +656,17 @@
mtx_lock(&xs.registered_watches_lock);
msg->u.watch.handle = find_watch(
msg->u.watch.vec[XS_WATCH_TOKEN]);
- if (msg->u.watch.handle != NULL) {
- mtx_lock(&xs.watch_events_lock);
+ mtx_lock(&xs.watch_events_lock);
+ if (msg->u.watch.handle != NULL &&
+ (!msg->u.watch.handle->max_pending ||
+ msg->u.watch.handle->pending <
+ msg->u.watch.handle->max_pending)) {
+ msg->u.watch.handle->pending++;
TAILQ_INSERT_TAIL(&xs.watch_events, msg, list);
wakeup(&xs.watch_events);
mtx_unlock(&xs.watch_events_lock);
} else {
+ mtx_unlock(&xs.watch_events_lock);
free(msg->u.watch.vec, M_XENSTORE);
free(msg, M_XENSTORE);
}
@@ -983,8 +988,10 @@
mtx_lock(&xs.watch_events_lock);
msg = TAILQ_FIRST(&xs.watch_events);
- if (msg)
+ if (msg) {
TAILQ_REMOVE(&xs.watch_events, msg, list);
+ msg->u.watch.handle->pending--;
+ }
mtx_unlock(&xs.watch_events_lock);
if (msg != NULL) {
@@ -1578,6 +1585,7 @@
char token[sizeof(watch) * 2 + 1];
int error;
+ watch->pending = 0;
sprintf(token, "%lX", (long)watch);
mtx_lock(&xs.registered_watches_lock);
--- sys/dev/xen/xenstore/xenstore_dev.c.orig
+++ sys/dev/xen/xenstore/xenstore_dev.c
@@ -45,6 +45,7 @@
#include <sys/conf.h>
#include <sys/module.h>
#include <sys/selinfo.h>
+#include <sys/sysctl.h>
#include <sys/poll.h>
#include <xen/xen-os.h>
@@ -53,6 +54,8 @@
#include <xen/xenstore/xenstorevar.h>
#include <xen/xenstore/xenstore_internal.h>
+static unsigned int max_pending_watches = 1000;
+
struct xs_dev_transaction {
LIST_ENTRY(xs_dev_transaction) list;
struct xs_transaction handle;
@@ -335,6 +338,7 @@
watch->watch.node = strdup(wpath, M_XENSTORE);
watch->watch.callback = xs_dev_watch_cb;
watch->watch.callback_data = (uintptr_t)watch;
+ watch->watch.max_pending = max_pending_watches;
watch->token = strdup(wtoken, M_XENSTORE);
watch->user = u;
@@ -511,6 +515,17 @@
xs_dev_attach(device_t dev)
{
struct cdev *xs_cdev;
+ struct sysctl_ctx_list *sysctl_ctx;
+ struct sysctl_oid *sysctl_tree;
+
+ sysctl_ctx = device_get_sysctl_ctx(dev);
+ sysctl_tree = device_get_sysctl_tree(dev);
+ if (sysctl_ctx == NULL || sysctl_tree == NULL)
+ return (EINVAL);
+
+ SYSCTL_ADD_UINT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
+ "max_pending_watch_events", CTLFLAG_RW, &max_pending_watches, 0,
+ "maximum amount of pending watch events to be delivered");
xs_cdev = make_dev_credf(MAKEDEV_ETERNAL, &xs_dev_cdevsw, 0, NULL,
UID_ROOT, GID_WHEEL, 0400, "xen/xenstore");
--- sys/xen/xenbus/xenbus.c.orig
+++ sys/xen/xenbus/xenbus.c
@@ -102,48 +102,6 @@
return ((state < (XenbusStateClosed + 1)) ? name[state] : "INVALID");
}
-int
-xenbus_watch_path(device_t dev, char *path, struct xs_watch *watch,
- xs_watch_cb_t *callback, uintptr_t callback_data)
-{
- int error;
-
- watch->node = path;
- watch->callback = callback;
- watch->callback_data = callback_data;
-
- error = xs_register_watch(watch);
-
- if (error) {
- watch->node = NULL;
- watch->callback = NULL;
- xenbus_dev_fatal(dev, error, "adding watch on %s", path);
- }
-
- return (error);
-}
-
-int
-xenbus_watch_path2(device_t dev, const char *path,
- const char *path2, struct xs_watch *watch,
- xs_watch_cb_t *callback, uintptr_t callback_data)
-{
- int error;
- char *state = malloc(strlen(path) + 1 + strlen(path2) + 1,
- M_XENBUS, M_WAITOK);
-
- strcpy(state, path);
- strcat(state, "/");
- strcat(state, path2);
-
- error = xenbus_watch_path(dev, state, watch, callback, callback_data);
- if (error) {
- free(state,M_XENBUS);
- }
-
- return (error);
-}
-
void
xenbus_dev_verror(device_t dev, int err, const char *fmt, va_list ap)
{
--- sys/xen/xenbus/xenbusb.c.orig
+++ sys/xen/xenbus/xenbusb.c
@@ -702,10 +702,21 @@
ivars->xd_otherend_watch.node = statepath;
ivars->xd_otherend_watch.callback = xenbusb_otherend_watch_cb;
ivars->xd_otherend_watch.callback_data = (uintptr_t)ivars;
+ /*
+ * Other end state node watch, limit to one pending event
+ * to prevent frontends from queuing too many events that
+ * could cause resource starvation.
+ */
+ ivars->xd_otherend_watch.max_pending = 1;
ivars->xd_local_watch.node = ivars->xd_node;
ivars->xd_local_watch.callback = xenbusb_local_watch_cb;
ivars->xd_local_watch.callback_data = (uintptr_t)ivars;
+ /*
+ * Watch our local path, only writable by us or a privileged
+ * domain, no need to limit.
+ */
+ ivars->xd_local_watch.max_pending = 0;
mtx_lock(&xbs->xbs_lock);
xbs->xbs_connecting_children++;
@@ -764,6 +775,12 @@
xbs->xbs_device_watch.node = bus_node;
xbs->xbs_device_watch.callback = xenbusb_devices_changed;
xbs->xbs_device_watch.callback_data = (uintptr_t)xbs;
+ /*
+ * Allow for unlimited pending watches, as those are local paths
+ * either controlled by the guest or only writable by privileged
+ * domains.
+ */
+ xbs->xbs_device_watch.max_pending = 0;
TASK_INIT(&xbs->xbs_probe_children, 0, xenbusb_probe_children_cb, dev);
--- sys/xen/xenbus/xenbusvar.h.orig
+++ sys/xen/xenbus/xenbusvar.h
@@ -123,62 +123,6 @@
return (xenbus_read_driver_state(xenbus_get_otherend_path(dev)));
}
-/**
- * Initialize and register a watch on the given path (client suplied storage).
- *
- * \param dev The XenBus device requesting the watch service.
- * \param path The XenStore path of the object to be watched. The
- * storage for this string must be stable for the lifetime
- * of the watch.
- * \param watch The watch object to use for this request. This object
- * must be stable for the lifetime of the watch.
- * \param callback The function to call when XenStore objects at or below
- * path are modified.
- * \param cb_data Client data that can be retrieved from the watch object
- * during the callback.
- *
- * \return On success, 0. Otherwise an errno value indicating the
- * type of failure.
- *
- * \note On error, the device 'dev' will be switched to the XenbusStateClosing
- * state and the returned error is saved in the per-device error node
- * for dev in the XenStore.
- */
-int xenbus_watch_path(device_t dev, char *path,
- struct xs_watch *watch,
- xs_watch_cb_t *callback,
- uintptr_t cb_data);
-
-/**
- * Initialize and register a watch at path/path2 in the XenStore.
- *
- * \param dev The XenBus device requesting the watch service.
- * \param path The base XenStore path of the object to be watched.
- * \param path2 The tail XenStore path of the object to be watched.
- * \param watch The watch object to use for this request. This object
- * must be stable for the lifetime of the watch.
- * \param callback The function to call when XenStore objects at or below
- * path are modified.
- * \param cb_data Client data that can be retrieved from the watch object
- * during the callback.
- *
- * \return On success, 0. Otherwise an errno value indicating the
- * type of failure.
- *
- * \note On error, \a dev will be switched to the XenbusStateClosing
- * state and the returned error is saved in the per-device error node
- * for \a dev in the XenStore.
- *
- * Similar to xenbus_watch_path, however the storage for the path to the
- * watched object is allocated from the heap and filled with "path '/' path2".
- * Should a call to this function succeed, it is the callers responsibility
- * to free watch->node using the M_XENBUS malloc type.
- */
-int xenbus_watch_path2(device_t dev, const char *path,
- const char *path2, struct xs_watch *watch,
- xs_watch_cb_t *callback,
- uintptr_t cb_data);
-
/**
* Grant access to the given ring_mfn to the peer of the given device.
*
--- sys/xen/xenstore/xenstorevar.h.orig
+++ sys/xen/xenstore/xenstorevar.h
@@ -70,6 +70,15 @@
/* Callback client data untouched by the XenStore watch mechanism. */
uintptr_t callback_data;
+
+ /* Maximum number of pending watch events to be delivered. */
+ unsigned int max_pending;
+
+ /*
+ * Private counter used by xenstore to keep track of the pending
+ * watches. Protected by xs.watch_events_lock.
+ */
+ unsigned int pending;
};
LIST_HEAD(xs_watch_list, xs_watch);
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