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From: Tony Krowiak <akrowiak@linux.ibm.com>
To: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org
Cc: freude@linux.ibm.com, borntraeger@de.ibm.com, cohuck@redhat.com,
	frankja@linux.ibm.com, david@redhat.com, mjrosato@linux.ibm.com,
	schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com,
	pmorel@linux.ibm.com, pasic@linux.ibm.com,
	alex.williamson@redhat.com, kwankhede@nvidia.com,
	Tony Krowiak <akrowiak@linux.ibm.com>
Subject: [PATCH v4 3/7] s390: zcrypt: driver callback to indicate resource in use
Date: Thu, 13 Jun 2019 15:39:36 -0400
Message-ID: <1560454780-20359-4-git-send-email-akrowiak@linux.ibm.com> (raw)
In-Reply-To: <1560454780-20359-1-git-send-email-akrowiak@linux.ibm.com>

Introduces a new driver callback to prevent a root user from unbinding
an AP queue from its device driver if the queue is in use. This prevents
a root user from inadvertently taking a queue away from a guest and
giving it to the host, or vice versa. The callback will be invoked
whenever a change to the AP bus's apmask or aqmask sysfs interfaces may
result in one or more AP queues being removed from its driver. If the
callback responds in the affirmative for any driver queried, the change
to the apmask or aqmask will be rejected with a device in use error.

For this patch, only non-default drivers will be queried. Currently,
there is only one non-default driver, the vfio_ap device driver. The
vfio_ap device driver manages AP queues passed through to one or more
guests and we don't want to unexpectedly take AP resources away from
guests which are most likely independently administered.

Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/ap_bus.c | 138 +++++++++++++++++++++++++++++++++++++++++--
 drivers/s390/crypto/ap_bus.h |   3 +
 2 files changed, 135 insertions(+), 6 deletions(-)

diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c
index b9fc502c58c2..1b06f47d0d1c 100644
--- a/drivers/s390/crypto/ap_bus.c
+++ b/drivers/s390/crypto/ap_bus.c
@@ -35,6 +35,7 @@
 #include <linux/mod_devicetable.h>
 #include <linux/debugfs.h>
 #include <linux/ctype.h>
+#include <linux/module.h>
 
 #include "ap_bus.h"
 #include "ap_debug.h"
@@ -998,9 +999,11 @@ int ap_parse_mask_str(const char *str,
 	newmap = kmalloc(size, GFP_KERNEL);
 	if (!newmap)
 		return -ENOMEM;
-	if (mutex_lock_interruptible(lock)) {
-		kfree(newmap);
-		return -ERESTARTSYS;
+	if (lock) {
+		if (mutex_lock_interruptible(lock)) {
+			kfree(newmap);
+			return -ERESTARTSYS;
+		}
 	}
 
 	if (*str == '+' || *str == '-') {
@@ -1012,7 +1015,10 @@ int ap_parse_mask_str(const char *str,
 	}
 	if (rc == 0)
 		memcpy(bitmap, newmap, size);
-	mutex_unlock(lock);
+
+	if (lock)
+		mutex_unlock(lock);
+
 	kfree(newmap);
 	return rc;
 }
@@ -1199,12 +1205,72 @@ static ssize_t apmask_show(struct bus_type *bus, char *buf)
 	return rc;
 }
 
+int __verify_card_reservations(struct device_driver *drv, void *data)
+{
+	int rc = 0;
+	struct ap_driver *ap_drv = to_ap_drv(drv);
+	unsigned long *newapm = (unsigned long *)data;
+
+	/*
+	 * If the reserved bits do not identify cards reserved for use by the
+	 * non-default driver, there is no need to verify the driver is using
+	 * the queues.
+	 */
+	if (ap_drv->flags & AP_DRIVER_FLAG_DEFAULT)
+		return 0;
+
+	/* The non-default driver's module must be loaded */
+	if (!try_module_get(drv->owner))
+		return 0;
+
+	if (ap_drv->in_use)
+		if (ap_drv->in_use(newapm, ap_perms.aqm))
+			rc = -EADDRINUSE;
+
+	module_put(drv->owner);
+
+	return rc;
+}
+
+static int apmask_commit(unsigned long *newapm)
+{
+	int rc;
+	unsigned long reserved[BITS_TO_LONGS(AP_DEVICES)];
+
+	/*
+	 * Check if any bits in the apmask have been set which will
+	 * result in queues being removed from non-default drivers
+	 */
+	if (bitmap_andnot(reserved, newapm, ap_perms.apm, AP_DEVICES)) {
+		rc = (bus_for_each_drv(&ap_bus_type, NULL, reserved,
+				       __verify_card_reservations));
+		if (rc)
+			return rc;
+	}
+
+	memcpy(ap_perms.apm, newapm, APMASKSIZE);
+
+	return 0;
+}
+
 static ssize_t apmask_store(struct bus_type *bus, const char *buf,
 			    size_t count)
 {
 	int rc;
+	unsigned long newapm[BITS_TO_LONGS(AP_DEVICES)];
+
+	memcpy(newapm, ap_perms.apm, APMASKSIZE);
+
+	rc = ap_parse_mask_str(buf, newapm, AP_DEVICES, NULL);
+	if (rc)
+		return rc;
+
+	if (mutex_lock_interruptible(&ap_perms_mutex))
+		return -ERESTARTSYS;
+
+	rc = apmask_commit(newapm);
+	mutex_unlock(&ap_perms_mutex);
 
-	rc = ap_parse_mask_str(buf, ap_perms.apm, AP_DEVICES, &ap_perms_mutex);
 	if (rc)
 		return rc;
 
@@ -1230,12 +1296,72 @@ static ssize_t aqmask_show(struct bus_type *bus, char *buf)
 	return rc;
 }
 
+int __verify_queue_reservations(struct device_driver *drv, void *data)
+{
+	int rc = 0;
+	struct ap_driver *ap_drv = to_ap_drv(drv);
+	unsigned long *newaqm = (unsigned long *)data;
+
+	/*
+	 * If the reserved bits do not identify queues reserved for use by the
+	 * non-default driver, there is no need to verify the driver is using
+	 * the queues.
+	 */
+	if (ap_drv->flags & AP_DRIVER_FLAG_DEFAULT)
+		return 0;
+
+	/* The non-default driver's module must be loaded */
+	if (!try_module_get(drv->owner))
+		return 0;
+
+	if (ap_drv->in_use)
+		if (ap_drv->in_use(ap_perms.apm, newaqm))
+			rc = -EADDRINUSE;
+
+	module_put(drv->owner);
+
+	return rc;
+}
+
+static int aqmask_commit(unsigned long *newaqm)
+{
+	int rc;
+	unsigned long reserved[BITS_TO_LONGS(AP_DOMAINS)];
+
+	/*
+	 * Check if any bits in the aqmask have been set which will
+	 * result in queues being removed from non-default drivers
+	 */
+	if (bitmap_andnot(reserved, newaqm, ap_perms.aqm, AP_DOMAINS)) {
+		rc = (bus_for_each_drv(&ap_bus_type, NULL, reserved,
+				       __verify_queue_reservations));
+		if (rc)
+			return rc;
+	}
+
+	memcpy(ap_perms.aqm, newaqm, APMASKSIZE);
+
+	return 0;
+}
+
 static ssize_t aqmask_store(struct bus_type *bus, const char *buf,
 			    size_t count)
 {
 	int rc;
+	unsigned long newaqm[BITS_TO_LONGS(AP_DEVICES)];
+
+	memcpy(newaqm, ap_perms.aqm, AQMASKSIZE);
+
+	rc = ap_parse_mask_str(buf, newaqm, AP_DOMAINS, NULL);
+	if (rc)
+		return rc;
+
+	if (mutex_lock_interruptible(&ap_perms_mutex))
+		return -ERESTARTSYS;
+
+	rc = aqmask_commit(newaqm);
+	mutex_unlock(&ap_perms_mutex);
 
-	rc = ap_parse_mask_str(buf, ap_perms.aqm, AP_DOMAINS, &ap_perms_mutex);
 	if (rc)
 		return rc;
 
diff --git a/drivers/s390/crypto/ap_bus.h b/drivers/s390/crypto/ap_bus.h
index 6f3cf37776ca..0f865c5545f2 100644
--- a/drivers/s390/crypto/ap_bus.h
+++ b/drivers/s390/crypto/ap_bus.h
@@ -137,6 +137,7 @@ struct ap_driver {
 	void (*remove)(struct ap_device *);
 	void (*suspend)(struct ap_device *);
 	void (*resume)(struct ap_device *);
+	bool (*in_use)(unsigned long *apm, unsigned long *aqm);
 };
 
 #define to_ap_drv(x) container_of((x), struct ap_driver, driver)
@@ -265,6 +266,8 @@ void ap_queue_reinit_state(struct ap_queue *aq);
 struct ap_card *ap_card_create(int id, int queue_depth, int raw_device_type,
 			       int comp_device_type, unsigned int functions);
 
+#define APMASKSIZE (BITS_TO_LONGS(AP_DEVICES) * sizeof(unsigned long))
+#define AQMASKSIZE (BITS_TO_LONGS(AP_DOMAINS) * sizeof(unsigned long))
 struct ap_perms {
 	unsigned long ioctlm[BITS_TO_LONGS(AP_IOCTLS)];
 	unsigned long apm[BITS_TO_LONGS(AP_DEVICES)];
-- 
2.7.4


  parent reply index

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-13 19:39 [PATCH v4 0/7] s390: vfio-ap: dynamic configuration support Tony Krowiak
2019-06-13 19:39 ` [PATCH v4 1/7] s390: vfio-ap: Refactor vfio_ap driver probe and remove callbacks Tony Krowiak
2019-06-17  8:27   ` Harald Freudenberger
2019-06-17 14:24     ` Tony Krowiak
2019-06-18 16:14   ` Cornelia Huck
2019-06-19 12:31     ` Tony Krowiak
2019-06-13 19:39 ` [PATCH v4 2/7] s390: vfio-ap: wait for queue empty on queue reset Tony Krowiak
2019-06-17  8:47   ` Harald Freudenberger
2019-06-17 14:29     ` Tony Krowiak
2019-06-13 19:39 ` Tony Krowiak [this message]
2019-06-17  9:28   ` [PATCH v4 3/7] s390: zcrypt: driver callback to indicate resource in use Harald Freudenberger
2019-06-17 14:37     ` Tony Krowiak
2019-06-18 16:25   ` Cornelia Huck
2019-06-19 13:04     ` Tony Krowiak
2019-06-26 21:13       ` Tony Krowiak
2019-06-27  7:25         ` Cornelia Huck
2019-06-27 12:59           ` Tony Krowiak
2019-07-01 19:26       ` Cornelia Huck
2019-07-08 14:27         ` Tony Krowiak
2019-07-09 10:49           ` Cornelia Huck
2019-07-09 21:11             ` Tony Krowiak
2019-06-13 19:39 ` [PATCH v4 4/7] s390: vfio-ap: implement in-use callback for vfio_ap driver Tony Krowiak
2019-06-13 19:39 ` [PATCH v4 5/7] s390: vfio-ap: allow assignment of unavailable AP resources to mdev device Tony Krowiak
2019-06-17 10:05   ` Harald Freudenberger
2019-06-17 15:07     ` Tony Krowiak
2019-06-18  6:49       ` Harald Freudenberger
2019-06-19 13:39         ` Tony Krowiak
2019-06-13 19:39 ` [PATCH v4 6/7] s390: vfio-ap: allow hot plug/unplug of AP resources using " Tony Krowiak
2019-06-13 19:39 ` [PATCH v4 7/7] s390: vfio-ap: update documentation Tony Krowiak
2019-06-17 11:42   ` Harald Freudenberger
2019-06-17 15:21     ` Tony Krowiak
2019-07-09 15:30 ` [PATCH v4 0/7] s390: vfio-ap: dynamic configuration support Halil Pasic

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