thunderbolt: Add support for de-authorizing devices

In some cases it is useful to be able de-authorize devices. For example
if user logs out the userspace can have a policy that disconnects PCIe
devices until logged in again. This is only possible for software based
connection manager as it directly controls the tunnels.

For this reason make the authorized attribute accept writing 0 which
makes the software connection manager to tear down the corresponding
PCIe tunnel. Userspace can check if this is supported by reading a new
domain attribute deauthorization, that holds 1 in that case.

While there correct tb_domain_approve_switch() kernel-doc and
description of authorized attribute to mention that it is only about
PCIe tunnels.

Cc: Christian Kellner <christian@kellner.me>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Yehezkel Bernat <YehezkelShB@gmail.com>

4 files changed, 86 insertions, 3 deletions

diff --git a/drivers/thunderbolt/domain.c b/drivers/thunderbolt/domain.c
index d2b92a8be577..9ba2181464cc 100644
--- a/drivers/thunderbolt/domain.c
+++ b/drivers/thunderbolt/domain.c
@@ -238,6 +238,16 @@ err_free_str:
 }
 static DEVICE_ATTR_RW(boot_acl);
 
+static ssize_t deauthorization_show(struct device *dev,
+				    struct device_attribute *attr,
+				    char *buf)
+{
+	const struct tb *tb = container_of(dev, struct tb, dev);
+
+	return sprintf(buf, "%d\n", !!tb->cm_ops->disapprove_switch);
+}
+static DEVICE_ATTR_RO(deauthorization);
+
 static ssize_t iommu_dma_protection_show(struct device *dev,
 					 struct device_attribute *attr,
 					 char *buf)
@@ -267,6 +277,7 @@ static DEVICE_ATTR_RO(security);
 
 static struct attribute *domain_attrs[] = {
 	&dev_attr_boot_acl.attr,
+	&dev_attr_deauthorization.attr,
 	&dev_attr_iommu_dma_protection.attr,
 	&dev_attr_security.attr,
 	NULL,
@@ -602,13 +613,30 @@ int tb_domain_runtime_resume(struct tb *tb)
 }
 
 /**
+ * tb_domain_disapprove_switch() - Disapprove switch
+ * @tb: Domain the switch belongs to
+ * @sw: Switch to disapprove
+ *
+ * This will disconnect PCIe tunnel from parent to this @sw.
+ *
+ * Return: %0 on success and negative errno in case of failure.
+ */
+int tb_domain_disapprove_switch(struct tb *tb, struct tb_switch *sw)
+{
+	if (!tb->cm_ops->disapprove_switch)
+		return -EPERM;
+
+	return tb->cm_ops->disapprove_switch(tb, sw);
+}
+
+/**
  * tb_domain_approve_switch() - Approve switch
  * @tb: Domain the switch belongs to
  * @sw: Switch to approve
  *
  * This will approve switch by connection manager specific means. In
- * case of success the connection manager will create tunnels for all
- * supported protocols.
+ * case of success the connection manager will create PCIe tunnel from
+ * parent to @sw.
  */
 int tb_domain_approve_switch(struct tb *tb, struct tb_switch *sw)
 {
diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index ad992e6204d9..cdba05e72486 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -1387,6 +1387,30 @@ static ssize_t authorized_show(struct device *dev,
 	return sprintf(buf, "%u\n", sw->authorized);
 }
 
+static int disapprove_switch(struct device *dev, void *not_used)
+{
+	struct tb_switch *sw;
+
+	sw = tb_to_switch(dev);
+	if (sw && sw->authorized) {
+		int ret;
+
+		/* First children */
+		ret = device_for_each_child_reverse(&sw->dev, NULL, disapprove_switch);
+		if (ret)
+			return ret;
+
+		ret = tb_domain_disapprove_switch(sw->tb, sw);
+		if (ret)
+			return ret;
+
+		sw->authorized = 0;
+		kobject_uevent(&sw->dev.kobj, KOBJ_CHANGE);
+	}
+
+	return 0;
+}
+
 static int tb_switch_set_authorized(struct tb_switch *sw, unsigned int val)
 {
 	int ret = -EINVAL;
@@ -1394,10 +1418,18 @@ static int tb_switch_set_authorized(struct tb_switch *sw, unsigned int val)
 	if (!mutex_trylock(&sw->tb->lock))
 		return restart_syscall();
 
-	if (sw->authorized)
+	if (!!sw->authorized == !!val)
 		goto unlock;
 
 	switch (val) {
+	/* Disapprove switch */
+	case 0:
+		if (tb_route(sw)) {
+			ret = disapprove_switch(&sw->dev, NULL);
+			goto unlock;
+		}
+		break;
+
 	/* Approve switch */
 	case 1:
 		if (sw->key)
diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index 51d5b031cada..d08879849abe 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -1002,6 +1002,25 @@ static void tb_disconnect_and_release_dp(struct tb *tb)
 	}
 }
 
+static int tb_disconnect_pci(struct tb *tb, struct tb_switch *sw)
+{
+	struct tb_tunnel *tunnel;
+	struct tb_port *up;
+
+	up = tb_switch_find_port(sw, TB_TYPE_PCIE_UP);
+	if (WARN_ON(!up))
+		return -ENODEV;
+
+	tunnel = tb_find_tunnel(tb, TB_TUNNEL_PCI, NULL, up);
+	if (WARN_ON(!tunnel))
+		return -ENODEV;
+
+	tb_tunnel_deactivate(tunnel);
+	list_del(&tunnel->list);
+	tb_tunnel_free(tunnel);
+	return 0;
+}
+
 static int tb_tunnel_pci(struct tb *tb, struct tb_switch *sw)
 {
 	struct tb_port *up, *down, *port;
@@ -1512,6 +1531,7 @@ static const struct tb_cm_ops tb_cm_ops = {
 	.runtime_suspend = tb_runtime_suspend,
 	.runtime_resume = tb_runtime_resume,
 	.handle_event = tb_handle_event,
+	.disapprove_switch = tb_disconnect_pci,
 	.approve_switch = tb_tunnel_pci,
 	.approve_xdomain_paths = tb_approve_xdomain_paths,
 	.disconnect_xdomain_paths = tb_disconnect_xdomain_paths,
diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
index 34ae83b9e52a..31468de658e4 100644
--- a/drivers/thunderbolt/tb.h
+++ b/drivers/thunderbolt/tb.h
@@ -361,6 +361,7 @@ struct tb_path {
  * @handle_event: Handle thunderbolt event
  * @get_boot_acl: Get boot ACL list
  * @set_boot_acl: Set boot ACL list
+ * @disapprove_switch: Disapprove switch (disconnect PCIe tunnel)
  * @approve_switch: Approve switch
  * @add_switch_key: Add key to switch
  * @challenge_switch_key: Challenge switch using key
@@ -394,6 +395,7 @@ struct tb_cm_ops {
 			     const void *buf, size_t size);
 	int (*get_boot_acl)(struct tb *tb, uuid_t *uuids, size_t nuuids);
 	int (*set_boot_acl)(struct tb *tb, const uuid_t *uuids, size_t nuuids);
+	int (*disapprove_switch)(struct tb *tb, struct tb_switch *sw);
 	int (*approve_switch)(struct tb *tb, struct tb_switch *sw);
 	int (*add_switch_key)(struct tb *tb, struct tb_switch *sw);
 	int (*challenge_switch_key)(struct tb *tb, struct tb_switch *sw,
@@ -629,6 +631,7 @@ int tb_domain_thaw_noirq(struct tb *tb);
 void tb_domain_complete(struct tb *tb);
 int tb_domain_runtime_suspend(struct tb *tb);
 int tb_domain_runtime_resume(struct tb *tb);
+int tb_domain_disapprove_switch(struct tb *tb, struct tb_switch *sw);
 int tb_domain_approve_switch(struct tb *tb, struct tb_switch *sw);
 int tb_domain_approve_switch_key(struct tb *tb, struct tb_switch *sw);
 int tb_domain_challenge_switch_key(struct tb *tb, struct tb_switch *sw);