[PATCH v4 4/4] vduse: Add LSM hooks to check Virtio device type

[Maxime Coquelin]

This patch introduces LSM hooks for devices creation,
destruction and opening operations, checking the
application is allowed to perform these operations for
the Virtio device type.

Signed-off-by: Maxime Coquelin <maxime.coquelin@xxxxxxxxxx>
---
 drivers/vdpa/vdpa_user/vduse_dev.c  | 12 +++++++
 include/linux/lsm_hook_defs.h       |  4 +++
 include/linux/security.h            | 15 ++++++++
 security/security.c                 | 42 ++++++++++++++++++++++
 security/selinux/hooks.c            | 55 +++++++++++++++++++++++++++++
 security/selinux/include/classmap.h |  2 ++
 6 files changed, 130 insertions(+)

diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index 0243dee9cf0e..ca64eac11ddb 100644
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -8,6 +8,7 @@
  *
  */
 
+#include "linux/security.h"
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/cdev.h>
@@ -1443,6 +1444,10 @@ static int vduse_dev_open(struct inode *inode, struct file *file)
 	if (dev->connected)
 		goto unlock;
 
+	ret = -EPERM;
+	if (security_vduse_dev_open(dev->device_id))
+		goto unlock;
+
 	ret = 0;
 	dev->connected = true;
 	file->private_data = dev;
@@ -1655,6 +1660,9 @@ static int vduse_destroy_dev(char *name)
 	if (!dev)
 		return -EINVAL;
 
+	if (security_vduse_dev_destroy(dev->device_id))
+		return -EPERM;
+
 	mutex_lock(&dev->lock);
 	if (dev->vdev || dev->connected) {
 		mutex_unlock(&dev->lock);
@@ -1819,6 +1827,10 @@ static int vduse_create_dev(struct vduse_dev_config *config,
 	int ret;
 	struct vduse_dev *dev;
 
+	ret = -EPERM;
+	if (security_vduse_dev_create(config->device_id))
+		goto err;
+
 	ret = -EEXIST;
 	if (vduse_find_dev(config->name))
 		goto err;
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index ac962c4cb44b..0b3999ab3264 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -419,3 +419,7 @@ LSM_HOOK(int, 0, uring_override_creds, const struct cred *new)
 LSM_HOOK(int, 0, uring_sqpoll, void)
 LSM_HOOK(int, 0, uring_cmd, struct io_uring_cmd *ioucmd)
 #endif /* CONFIG_IO_URING */
+
+LSM_HOOK(int, 0, vduse_dev_create, u32 device_id)
+LSM_HOOK(int, 0, vduse_dev_destroy, u32 device_id)
+LSM_HOOK(int, 0, vduse_dev_open, u32 device_id)
diff --git a/include/linux/security.h b/include/linux/security.h
index 5f16eecde00b..a650c500f841 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -484,6 +484,9 @@ int security_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen);
 int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen);
 int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen);
 int security_locked_down(enum lockdown_reason what);
+int security_vduse_dev_create(u32 device_id);
+int security_vduse_dev_destroy(u32 device_id);
+int security_vduse_dev_open(u32 device_id);
 #else /* CONFIG_SECURITY */
 
 static inline int call_blocking_lsm_notifier(enum lsm_event event, void *data)
@@ -1395,6 +1398,18 @@ static inline int security_locked_down(enum lockdown_reason what)
 {
 	return 0;
 }
+static inline int security_vduse_dev_create(u32 device_id)
+{
+	return 0;
+}
+static inline int security_vduse_dev_destroy(u32 device_id)
+{
+	return 0;
+}
+static inline int security_vduse_dev_open(u32 device_id)
+{
+	return 0;
+}
 #endif	/* CONFIG_SECURITY */
 
 #if defined(CONFIG_SECURITY) && defined(CONFIG_WATCH_QUEUE)
diff --git a/security/security.c b/security/security.c
index 23b129d482a7..8d7d4d2eca0b 100644
--- a/security/security.c
+++ b/security/security.c
@@ -5337,3 +5337,45 @@ int security_uring_cmd(struct io_uring_cmd *ioucmd)
 	return call_int_hook(uring_cmd, 0, ioucmd);
 }
 #endif /* CONFIG_IO_URING */
+
+/**
+ * security_vduse_dev_create() - Check if a VDUSE device type creation is allowed
+ * @device_id: the Virtio device ID
+ *
+ * Check whether the Virtio device creation is allowed
+ *
+ * Return: Returns 0 if permission is granted.
+ */
+int security_vduse_dev_create(u32 device_id)
+{
+	return call_int_hook(vduse_dev_create, 0, device_id);
+}
+EXPORT_SYMBOL(security_vduse_dev_create);
+
+/**
+ * security_vduse_dev_destroy() - Check if a VDUSE device type destruction is allowed
+ * @device_id: the Virtio device ID
+ *
+ * Check whether the Virtio device destruction is allowed
+ *
+ * Return: Returns 0 if permission is granted.
+ */
+int security_vduse_dev_destroy(u32 device_id)
+{
+	return call_int_hook(vduse_dev_destroy, 0, device_id);
+}
+EXPORT_SYMBOL(security_vduse_dev_destroy);
+
+/**
+ * security_vduse_dev_open() - Check if a VDUSE device type opening is allowed
+ * @device_id: the Virtio device ID
+ *
+ * Check whether the Virtio device opening is allowed
+ *
+ * Return: Returns 0 if permission is granted.
+ */
+int security_vduse_dev_open(u32 device_id)
+{
+	return call_int_hook(vduse_dev_open, 0, device_id);
+}
+EXPORT_SYMBOL(security_vduse_dev_open);
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 2aa0e219d721..65d9262a37f7 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -21,6 +21,7 @@
  *  Copyright (C) 2016 Mellanox Technologies
  */
 
+#include "av_permissions.h"
 #include <linux/init.h>
 #include <linux/kd.h>
 #include <linux/kernel.h>
@@ -92,6 +93,7 @@
 #include <linux/fsnotify.h>
 #include <linux/fanotify.h>
 #include <linux/io_uring.h>
+#include <uapi/linux/virtio_ids.h>
 
 #include "avc.h"
 #include "objsec.h"
@@ -6950,6 +6952,56 @@ static int selinux_uring_cmd(struct io_uring_cmd *ioucmd)
 }
 #endif /* CONFIG_IO_URING */
 
+static int vduse_check_device_type(u32 sid, u32 device_id)
+{
+	u32 requested;
+
+	if (device_id == VIRTIO_ID_NET)
+		requested = VDUSE__NET;
+	else if (device_id == VIRTIO_ID_BLOCK)
+		requested = VDUSE__BLOCK;
+	else
+		return -EINVAL;
+
+	return avc_has_perm(sid, sid, SECCLASS_VDUSE, requested, NULL);
+}
+
+static int selinux_vduse_dev_create(u32 device_id)
+{
+	u32 sid = current_sid();
+	int ret;
+
+	ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVCREATE, NULL);
+	if (ret)
+		return ret;
+
+	return vduse_check_device_type(sid, device_id);
+}
+
+static int selinux_vduse_dev_destroy(u32 device_id)
+{
+	u32 sid = current_sid();
+	int ret;
+
+	ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVDESTROY, NULL);
+	if (ret)
+		return ret;
+
+	return vduse_check_device_type(sid, device_id);
+}
+
+static int selinux_vduse_dev_open(u32 device_id)
+{
+	u32 sid = current_sid();
+	int ret;
+
+	ret = avc_has_perm(sid, sid, SECCLASS_VDUSE, VDUSE__DEVOPEN, NULL);
+	if (ret)
+		return ret;
+
+	return vduse_check_device_type(sid, device_id);
+}
+
 /*
  * IMPORTANT NOTE: When adding new hooks, please be careful to keep this order:
  * 1. any hooks that don't belong to (2.) or (3.) below,
@@ -7243,6 +7295,9 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = {
 #ifdef CONFIG_PERF_EVENTS
 	LSM_HOOK_INIT(perf_event_alloc, selinux_perf_event_alloc),
 #endif
+	LSM_HOOK_INIT(vduse_dev_create, selinux_vduse_dev_create),
+	LSM_HOOK_INIT(vduse_dev_destroy, selinux_vduse_dev_destroy),
+	LSM_HOOK_INIT(vduse_dev_open, selinux_vduse_dev_open),
 };
 
 static __init int selinux_init(void)
diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h
index a3c380775d41..d3dc37fb03d4 100644
--- a/security/selinux/include/classmap.h
+++ b/security/selinux/include/classmap.h
@@ -256,6 +256,8 @@ const struct security_class_mapping secclass_map[] = {
 	  { "override_creds", "sqpoll", "cmd", NULL } },
 	{ "user_namespace",
 	  { "create", NULL } },
+	{ "vduse",
+	  { "devcreate", "devdestroy", "devopen", "net", "block", NULL} },
 	{ NULL }
   };
 
-- 
2.41.0