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driver: core: add security labels to devtmpfs

PATCH In review Namjae Jeon 2 participants 4 messages Jun 5, 2015

Subsystems (23)
DRM drivers Media (V4L/DVB) x86 USB +19 more subsystems
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Namjae Jeon

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PATCH 2/3 driver: core: add security labels to devtmpfs

Add support for setting security labels(e.g. smack or selinux labels) to devtmpfs device nodes. In this manner, drivers can specify desired security label in their device_type->devnode or class->devnode method.

Signed-off-by Namjae Jeon <[email protected]>
Signed-off-by Vivek Trivedi <[email protected]>
---
 arch/x86/kernel/cpuid.c                    |  2 +-
 arch/x86/kernel/msr.c                      |  2 +-
 block/bsg.c                                |  2 +-
 block/genhd.c                              |  2 +-
 drivers/base/core.c                        |  9 +++++----
 drivers/base/devtmpfs.c                    | 23 +++++++++++++++++------
 drivers/block/aoe/aoechr.c                 |  2 +-
 drivers/block/pktcdvd.c                    |  2 +-
 drivers/char/mem.c                         |  2 +-
 drivers/char/misc.c                        |  2 +-
 drivers/char/raw.c                         |  2 +-
 drivers/char/tile-srom.c                   |  2 +-
 drivers/gpu/drm/drm_sysfs.c                |  2 +-
 drivers/hid/usbhid/hiddev.c                |  2 +-
 drivers/infiniband/core/cm.c               |  2 +-
 drivers/infiniband/core/user_mad.c         |  2 +-
 drivers/infiniband/core/uverbs_main.c      |  2 +-
 drivers/input/input.c                      |  2 +-
 drivers/media/dvb-core/dvbdev.c            |  2 +-
 drivers/media/pci/ddbridge/ddbridge-core.c |  2 +-
 drivers/misc/cxl/file.c                    |  2 +-
 drivers/s390/char/hmcdrv_dev.c             |  2 +-
 drivers/tty/tty_io.c                       |  2 +-
 drivers/usb/class/usblp.c                  |  2 +-
 drivers/usb/core/file.c                    |  4 ++--
 drivers/usb/core/usb.c                     |  3 ++-
 drivers/usb/misc/iowarrior.c               |  2 +-
 drivers/usb/misc/legousbtower.c            |  2 +-
 drivers/vfio/vfio.c                        |  2 +-
 fs/pstore/pmsg.c                           |  2 +-
 include/linux/device.h                     |  7 ++++---
 include/linux/usb.h                        |  2 +-
 sound/sound_core.c                         |  2 +-
 33 files changed, 58 insertions(+), 44 deletions(-)
arch/x86/kernel/cpuid.c +1 -1
index 7153cb7..1623e4c 100644
@@ -176,7 +176,7 @@ static struct notifier_block __refdata cpuid_class_cpu_notifier =
 };
 
 static char *cpuid_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	return kasprintf(GFP_KERNEL, "cpu/%u/cpuid", MINOR(dev->devt));
 }
arch/x86/kernel/msr.c +1 -1
index fcbd718..29b143b 100644
@@ -240,7 +240,7 @@ static struct notifier_block __refdata msr_class_cpu_notifier = {
 };
 
 static char *msr_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt));
 }
block/bsg.c +1 -1
index 6eef206..ee383b2 100644
@@ -1041,7 +1041,7 @@ EXPORT_SYMBOL_GPL(bsg_register_queue);
 static struct cdev bsg_cdev;
 
 static char *bsg_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
 }
block/genhd.c +1 -1
index 59d18b6..7cff560 100644
@@ -1121,7 +1121,7 @@ struct class block_class = {
 };
 
 static char *block_devnode(struct device *dev, umode_t *mode,
-			   kuid_t *uid, kgid_t *gid)
+			   kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	struct gendisk *disk = dev_to_disk(dev);
drivers/base/core.c +5 -4
index 4e7546d..0007bc3 100644
@@ -311,7 +311,7 @@ static int dev_uevent(struct kset *kset, struct kobject *kobj,
 
 		add_uevent_var(env, "MAJOR=%u", MAJOR(dev->devt));
 		add_uevent_var(env, "MINOR=%u", MINOR(dev->devt));
-		name = device_get_devnode(dev, &mode, &uid, &gid, &tmp);
+		name = device_get_devnode(dev, &mode, &uid, &gid, NULL, &tmp);
 		if (name) {
 			add_uevent_var(env, "DEVNAME=%s", name);
 			if (mode)

@@ -1271,6 +1271,7 @@ static struct device *next_device(struct klist_iter *i)
  * @mode: returned file access mode
  * @uid: returned file owner
  * @gid: returned file group
+ * @xattr: returned file xattr
  * @tmp: possibly allocated string
  *
  * Return the relative path of a possible device node.

@@ -1280,7 +1281,7 @@ static struct device *next_device(struct klist_iter *i)
  */
 const char *device_get_devnode(struct device *dev,
 			       umode_t *mode, kuid_t *uid, kgid_t *gid,
-			       const char **tmp)
+			       struct xattr *xattr, const char **tmp)
 {
 	char *s;
 

@@ -1288,13 +1289,13 @@ const char *device_get_devnode(struct device *dev,
 
 	/* the device type may provide a specific name */
 	if (dev->type && dev->type->devnode)
-		*tmp = dev->type->devnode(dev, mode, uid, gid);
+		*tmp = dev->type->devnode(dev, mode, uid, gid, xattr);
 	if (*tmp)
 		return *tmp;
 
 	/* the class may provide a specific name */
 	if (dev->class && dev->class->devnode)
-		*tmp = dev->class->devnode(dev, mode, uid, gid);
+		*tmp = dev->class->devnode(dev, mode, uid, gid, xattr);
 	if (*tmp)
 		return *tmp;
drivers/base/devtmpfs.c +17 -6
index 68f0314..c628afb 100644
@@ -44,6 +44,7 @@ static struct req {
 	umode_t mode;	/* 0 => delete */
 	kuid_t uid;
 	kgid_t gid;
+	struct xattr xattr;
 	struct device *dev;
 } *requests;
 

@@ -90,7 +91,12 @@ int devtmpfs_create_node(struct device *dev)
 	req.mode = 0;
 	req.uid = GLOBAL_ROOT_UID;
 	req.gid = GLOBAL_ROOT_GID;
-	req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
+	req.xattr.value = kmalloc(XATTR_SIZE_MAX, GFP_KERNEL);
+	if (!req.xattr.value)
+		return -ENOMEM;
+	req.xattr.value_len = 0;
+	req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid,
+			&req.xattr, &tmp);
 	if (!req.name)
 		return -ENOMEM;
 

@@ -113,6 +119,7 @@ int devtmpfs_create_node(struct device *dev)
 	wake_up_process(thread);
 	wait_for_completion(&req.done);
 
+	kfree(req.xattr.value);
 	kfree(tmp);
 
 	return req.err;

@@ -126,7 +133,7 @@ int devtmpfs_delete_node(struct device *dev)
 	if (!thread)
 		return 0;
 
-	req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
+	req.name = device_get_devnode(dev, NULL, NULL, NULL, NULL, &tmp);
 	if (!req.name)
 		return -ENOMEM;
 

@@ -193,7 +200,7 @@ static int create_path(const char *nodepath)
 }
 
 static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
-			 kgid_t gid, struct device *dev)
+			 kgid_t gid, struct xattr xattr, struct device *dev)
 {
 	struct dentry *dentry;
 	struct path path;

@@ -221,6 +228,9 @@ static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
 
 		/* mark as kernel-created inode */
 		d_inode(dentry)->i_private = &thread;
+		if (xattr.value_len > 0)
+			vfs_setxattr(dentry, xattr.name, xattr.value,
+					xattr.value_len, 0);
 	}
 	done_path_create(&path, dentry);
 	return err;

@@ -365,10 +375,10 @@ int devtmpfs_mount(const char *mntdir)
 static DECLARE_COMPLETION(setup_done);
 
 static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
-		  struct device *dev)
+		struct xattr xattr, struct device *dev)
 {
 	if (mode)
-		return handle_create(name, mode, uid, gid, dev);
+		return handle_create(name, mode, uid, gid, xattr, dev);
 	else
 		return handle_remove(name, dev);
 }

@@ -395,7 +405,8 @@ static int devtmpfsd(void *p)
 			while (req) {
 				struct req *next = req->next;
 				req->err = handle(req->name, req->mode,
-						  req->uid, req->gid, req->dev);
+						  req->uid, req->gid,
+						  req->xattr, req->dev);
 				complete(&req->done);
 				req = next;
 			}
drivers/block/aoe/aoechr.c +1 -1
index a71332f..41612e4 100644
@@ -276,7 +276,7 @@ static const struct file_operations aoe_fops = {
 };
 
 static char *aoe_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	return kasprintf(GFP_KERNEL, "etherd/%s", dev_name(dev));
 }
drivers/block/pktcdvd.c +1 -1
index 5f5c462..3fd2251 100644
@@ -2732,7 +2732,7 @@ static const struct block_device_operations pktcdvd_ops = {
 };
 
 static char *pktcdvd_devnode(struct gendisk *gd, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	return kasprintf(GFP_KERNEL, "pktcdvd/%s", gd->disk_name);
 }
drivers/char/mem.c +1 -1
index f16b511..57ffee6 100644
@@ -832,7 +832,7 @@ static const struct file_operations memory_fops = {
 };
 
 static char *mem_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	if (mode && devlist[MINOR(dev->devt)].mode)
 		*mode = devlist[MINOR(dev->devt)].mode;
drivers/char/misc.c +1 -1
index 9a960ab..63fb739 100644
@@ -268,7 +268,7 @@ EXPORT_SYMBOL(misc_register);
 EXPORT_SYMBOL(misc_deregister);
 
 static char *misc_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	struct miscdevice *c = dev_get_drvdata(dev);
drivers/char/raw.c +1 -1
index d6714ee..ba8566e 100644
@@ -306,7 +306,7 @@ static const struct file_operations raw_ctl_fops = {
 static struct cdev raw_cdev;
 
 static char *raw_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	return kasprintf(GFP_KERNEL, "raw/%s", dev_name(dev));
 }
drivers/char/tile-srom.c +1 -1
index 1b6f655..fae0008 100644
@@ -311,7 +311,7 @@ static struct attribute *srom_dev_attrs[] = {
 ATTRIBUTE_GROUPS(srom_dev);
 
 static char *srom_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	*mode = S_IRUGO | S_IWUSR;
 	return kasprintf(GFP_KERNEL, "srom/%s", dev_name(dev));
drivers/gpu/drm/drm_sysfs.c +1 -1
index 48ec1b6..6afd5cbd 100644
@@ -100,7 +100,7 @@ static const struct dev_pm_ops drm_class_dev_pm_ops = {
 };
 
 static char *drm_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	return kasprintf(GFP_KERNEL, "dri/%s", dev_name(dev));
 }
drivers/hid/usbhid/hiddev.c +1 -1
index a40204b..b5176cc 100644
@@ -861,7 +861,7 @@ static const struct file_operations hiddev_fops = {
 };
 
 static char *hiddev_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	return kasprintf(GFP_KERNEL, "usb/%s", dev_name(dev));
 }
drivers/infiniband/core/cm.c +1 -1
index 13621fd4..551d990 100644
@@ -3692,7 +3692,7 @@ static struct kobj_type cm_port_obj_type = {
 };
 
 static char *cm_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	if (mode)
 		*mode = 0666;
drivers/infiniband/core/user_mad.c +1 -1
index dc34a45..a51c93f 100644
@@ -1333,7 +1333,7 @@ static void ib_umad_remove_one(struct ib_device *device)
 }
 
 static char *umad_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	return kasprintf(GFP_KERNEL, "infiniband/%s", dev_name(dev));
 }
drivers/infiniband/core/uverbs_main.c +1 -1
index 86c0311..95b0d37 100644
@@ -969,7 +969,7 @@ static void ib_uverbs_remove_one(struct ib_device *device)
 }
 
 static char *uverbs_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	if (mode)
 		*mode = 0666;
drivers/input/input.c +1 -1
index f4825b7..630c78b 100644
@@ -1760,7 +1760,7 @@ static struct device_type input_dev_type = {
 };
 
 static char *input_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	return kasprintf(GFP_KERNEL, "input/%s", dev_name(dev));
 }
drivers/media/dvb-core/dvbdev.c +1 -1
index 5ec225e..4c450d3 100644
@@ -585,7 +585,7 @@ static int dvb_uevent(struct device *dev, struct kobj_uevent_env *env)
 }
 
 static char *dvb_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	struct dvb_device *dvbdev = dev_get_drvdata(dev);
drivers/media/pci/ddbridge/ddbridge-core.c +1 -1
index 44d9bc6..215550d 100644
@@ -1477,7 +1477,7 @@ static const struct file_operations ddb_fops = {
 };
 
 static char *ddb_devnode(struct device *device, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	struct ddb *dev = dev_get_drvdata(device);
drivers/misc/cxl/file.c +1 -1
index f570d50..7dd8c39 100644
@@ -409,7 +409,7 @@ const struct file_operations afu_master_fops = {
 
 
 static char *cxl_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	if (CXL_DEVT_IS_CARD(dev->devt)) {
 		/*
drivers/s390/char/hmcdrv_dev.c +1 -1
index ffa582a..1baa752 100644
@@ -90,7 +90,7 @@ static dev_t hmcdrv_dev_no; /* device number (major/minor) */
  * Return: recommended device file name in /dev
  */
 static char *hmcdrv_dev_name(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	char *nodename = NULL;
 	const char *devname = dev_name(dev); /* kernel device name */
drivers/tty/tty_io.c +1 -1
index a47650a..1333290 100644
@@ -3529,7 +3529,7 @@ void __init console_init(void)
 }
 
 static char *tty_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	if (!mode)
 		return NULL;
drivers/usb/class/usblp.c +1 -1
index d672115..312e084 100644
@@ -1059,7 +1059,7 @@ static const struct file_operations usblp_fops = {
 };
 
 static char *usblp_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	return kasprintf(GFP_KERNEL, "usb/%s", dev_name(dev));
 }
drivers/usb/core/file.c +2 -2
index e990b8d..6754de9 100644
@@ -59,14 +59,14 @@ static struct usb_class {
 } *usb_class;
 
 static char *usb_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	struct usb_class_driver *drv;
 
 	drv = dev_get_drvdata(dev);
 	if (!drv || !drv->devnode)
 		return NULL;
-	return drv->devnode(dev, mode, uid, gid);
+	return drv->devnode(dev, mode, uid, gid, xattr);
 }
 
 static int init_usb_class(void)
drivers/usb/core/usb.c +2 -1
index 8d5b2f4..1f1f5cf 100644
@@ -373,7 +373,8 @@ static const struct dev_pm_ops usb_device_pm_ops = {
 
 
 static char *usb_devnode(struct device *dev,
-			 umode_t *mode, kuid_t *uid, kgid_t *gid)
+			 umode_t *mode, kuid_t *uid, kgid_t *gid,
+			 struct xattr *xattr)
 {
 	struct usb_device *usb_dev;
drivers/usb/misc/iowarrior.c +1 -1
index f9d6887..4764d79 100644
@@ -730,7 +730,7 @@ static const struct file_operations iowarrior_fops = {
 };
 
 static char *iowarrior_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	return kasprintf(GFP_KERNEL, "usb/%s", dev_name(dev));
 }
drivers/usb/misc/legousbtower.c +1 -1
index d41c1b8..0830f48 100644
@@ -254,7 +254,7 @@ static const struct file_operations tower_fops = {
 };
 
 static char *legousbtower_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	return kasprintf(GFP_KERNEL, "usb/%s", dev_name(dev));
 }
drivers/vfio/vfio.c +1 -1
index 58e4e67..757a866 100644
@@ -1520,7 +1520,7 @@ EXPORT_SYMBOL_GPL(vfio_external_check_extension);
  * Module/class support
  */
 static char *vfio_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	return kasprintf(GFP_KERNEL, "vfio/%s", dev_name(dev));
 }
fs/pstore/pmsg.c +1 -1
index 2d7db92..189675d 100644
@@ -74,7 +74,7 @@ static int pmsg_major;
 #define pr_fmt(fmt) PMSG_NAME ": " fmt
 
 static char *pmsg_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	if (mode)
 		*mode = 0220;
include/linux/device.h +4 -3
index 220c0b1..135b12d 100644
@@ -27,6 +27,7 @@
 #include <linux/ratelimit.h>
 #include <linux/uidgid.h>
 #include <linux/gfp.h>
+#include <linux/xattr.h>
 #include <asm/device.h>
 
 struct device;

@@ -390,7 +391,7 @@ struct class {
 
 	int (*dev_uevent)(struct device *dev, struct kobj_uevent_env *env);
 	char *(*devnode)(struct device *dev, umode_t *mode,
-			kuid_t *uid, kgid_t *gid);
+			kuid_t *uid, kgid_t *gid, struct xattr *xattr);
 
 	void (*class_release)(struct class *class);
 	void (*dev_release)(struct device *dev);

@@ -535,7 +536,7 @@ struct device_type {
 	const struct attribute_group **groups;
 	int (*uevent)(struct device *dev, struct kobj_uevent_env *env);
 	char *(*devnode)(struct device *dev, umode_t *mode,
-			 kuid_t *uid, kgid_t *gid);
+			 kuid_t *uid, kgid_t *gid, struct xattr *xattr);
 	void (*release)(struct device *dev);
 
 	const struct dev_pm_ops *pm;

@@ -966,7 +967,7 @@ extern int device_move(struct device *dev, struct device *new_parent,
 		       enum dpm_order dpm_order);
 extern const char *device_get_devnode(struct device *dev,
 				      umode_t *mode, kuid_t *uid, kgid_t *gid,
-				      const char **tmp);
+				      struct xattr *xattr, const char **tmp);
 
 static inline bool device_supports_offline(struct device *dev)
 {
include/linux/usb.h +1 -1
index c396dde..4165606 100644
@@ -1158,7 +1158,7 @@ extern struct bus_type usb_bus_type;
 struct usb_class_driver {
 	char *name;
 	char *(*devnode)(struct device *dev, umode_t *mode,
-			kuid_t *uid, kgid_t *gid);
+			kuid_t *uid, kgid_t *gid, struct xattr *xattr);
 	const struct file_operations *fops;
 	int minor_base;
 };
sound/sound_core.c +1 -1
index 9c01786..b2145f8 100644
@@ -30,7 +30,7 @@ MODULE_AUTHOR("Alan Cox");
 MODULE_LICENSE("GPL");
 
 static char *sound_devnode(struct device *dev, umode_t *mode,
-		kuid_t *uid, kgid_t *gid)
+		kuid_t *uid, kgid_t *gid, struct xattr *xattr)
 {
 	if (MAJOR(dev->devt) == SOUND_MAJOR)
 		return NULL;
Signature · 1 line
1.8.5.5
maintainer
#1 lore raw
Quoted 3 lines · Namjae Jeon

Add support for setting security labels(e.g. smack or selinux labels) to devtmpfs device nodes. In this manner, drivers can specify desired security label in their device_type->devnode or class->devnode method.

What driver wants to do this? And how does it determine the proper security label from within the kernel? Isn't that something that only userspace can know/set properly?

thanks,

greg k-h

author
#2 lore raw
Quoted 8 lines · Namjae Jeon
Quoted 3 lines

Add support for setting security labels(e.g. smack or selinux labels) to devtmpfs device nodes. In this manner, drivers can specify desired security label in their device_type->devnode or class->devnode method.

What driver wants to do this? And how does it determine the proper security label from within the kernel? Isn't that something that only userspace can know/set properly?

Yes, It is possible by userspace, But This api change will help to set uid/gid and xattr values easily without need of complex userspace scripts in absence of udev like helper.
And security label that decided as per each embedded system will be set by this api in driver.

Quoted 4 lines

thanks,

greg k-h

maintainer
#3 lore raw
Quoted 11 lines · Namjae Jeon
Quoted 8 lines · Namjae Jeon
Quoted 3 lines

Add support for setting security labels(e.g. smack or selinux labels) to devtmpfs device nodes. In this manner, drivers can specify desired security label in their device_type->devnode or class->devnode method.

What driver wants to do this? And how does it determine the proper security label from within the kernel? Isn't that something that only userspace can know/set properly?

Yes, It is possible by userspace, But This api change will help to set uid/gid and xattr values easily without need of complex userspace scripts in absence of udev like helper.

If you want to do things like this, use a "complex" userspace script like Android has for their startup (hint, it's just a tiny bash script, nothing "complex" about it at all...)

Quoted 2 lines

And security label that decided as per each embedded system will be set by this api in driver.

Exactly how will that happen? I don't see any users of it.

greg k-h