Driver-Core: extend devnode callbacks to provide permissions

This allows subsytems to provide devtmpfs with non-default permissions
for the device node. Instead of the default mode of 0600, null, zero,
random, urandom, full, tty, ptmx now have a mode of 0666, which allows
non-privileged processes to access standard device nodes in case no
other userspace process applies the expected permissions.

This also fixes a wrong assignment in pktcdvd and a checkpatch.pl complain.

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

arch/x86/kernel/cpuid.c

@@ -182,7 +182,7 @@ static struct notifier_block __refdata cpuid_class_cpu_notifier =
 	.notifier_call = cpuid_class_cpu_callback,
 };
 
-static char *cpuid_nodename(struct device *dev)
+static char *cpuid_devnode(struct device *dev, mode_t *mode)
 {
 	return kasprintf(GFP_KERNEL, "cpu/%u/cpuid", MINOR(dev->devt));
 }
@@ -203,7 +203,7 @@ static int __init cpuid_init(void)
 		err = PTR_ERR(cpuid_class);
 		goto out_chrdev;
 	}
-	cpuid_class->nodename = cpuid_nodename;
+	cpuid_class->devnode = cpuid_devnode;
 	for_each_online_cpu(i) {
 		err = cpuid_device_create(i);
 		if (err != 0)

arch/x86/kernel/microcode_core.c

@@ -236,7 +236,7 @@ static const struct file_operations microcode_fops = {
 static struct miscdevice microcode_dev = {
 	.minor			= MICROCODE_MINOR,
 	.name			= "microcode",
-	.devnode		= "cpu/microcode",
+	.nodename		= "cpu/microcode",
 	.fops			= &microcode_fops,
 };
 

arch/x86/kernel/msr.c

@@ -241,7 +241,7 @@ static struct notifier_block __refdata msr_class_cpu_notifier = {
 	.notifier_call = msr_class_cpu_callback,
 };
 
-static char *msr_nodename(struct device *dev)
+static char *msr_devnode(struct device *dev, mode_t *mode)
 {
 	return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt));
 }
@@ -262,7 +262,7 @@ static int __init msr_init(void)
 		err = PTR_ERR(msr_class);
 		goto out_chrdev;
 	}
-	msr_class->nodename = msr_nodename;
+	msr_class->devnode = msr_devnode;
 	for_each_online_cpu(i) {
 		err = msr_device_create(i);
 		if (err != 0)

block/bsg.c

@@ -1062,7 +1062,7 @@ EXPORT_SYMBOL_GPL(bsg_register_queue);
 
 static struct cdev bsg_cdev;
 
-static char *bsg_nodename(struct device *dev)
+static char *bsg_devnode(struct device *dev, mode_t *mode)
 {
 	return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
 }
@@ -1087,7 +1087,7 @@ static int __init bsg_init(void)
 		ret = PTR_ERR(bsg_class);
 		goto destroy_kmemcache;
 	}
-	bsg_class->nodename = bsg_nodename;
+	bsg_class->devnode = bsg_devnode;
 
 	ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
 	if (ret)

block/genhd.c

@@ -998,20 +998,20 @@ struct class block_class = {
 	.name		= "block",
 };
 
-static char *block_nodename(struct device *dev)
+static char *block_devnode(struct device *dev, mode_t *mode)
 {
 	struct gendisk *disk = dev_to_disk(dev);
 
-	if (disk->nodename)
-		return disk->nodename(disk);
+	if (disk->devnode)
+		return disk->devnode(disk, mode);
 	return NULL;
 }
 
 static struct device_type disk_type = {
 	.name		= "disk",
 	.groups		= disk_attr_groups,
 	.release	= disk_release,
-	.nodename	= block_nodename,
+	.devnode	= block_devnode,
 };
 
 #ifdef CONFIG_PROC_FS

drivers/base/core.c

@@ -166,13 +166,16 @@ static int dev_uevent(struct kset *kset, struct kobject *kobj,
 	if (MAJOR(dev->devt)) {
 		const char *tmp;
 		const char *name;
+		mode_t mode = 0;
 
 		add_uevent_var(env, "MAJOR=%u", MAJOR(dev->devt));
 		add_uevent_var(env, "MINOR=%u", MINOR(dev->devt));
-		name = device_get_nodename(dev, &tmp);
+		name = device_get_devnode(dev, &mode, &tmp);
 		if (name) {
 			add_uevent_var(env, "DEVNAME=%s", name);
 			kfree(tmp);
+			if (mode)
+				add_uevent_var(env, "DEVMODE=%#o", mode & 0777);
 		}
 	}
 
@@ -1148,30 +1151,32 @@ static struct device *next_device(struct klist_iter *i)
 }
 
 /**
- * device_get_nodename - path of device node file
+ * device_get_devnode - path of device node file
  * @dev: device
+ * @mode: returned file access mode
  * @tmp: possibly allocated string
  *
  * Return the relative path of a possible device node.
  * Non-default names may need to allocate a memory to compose
  * a name. This memory is returned in tmp and needs to be
  * freed by the caller.
  */
-const char *device_get_nodename(struct device *dev, const char **tmp)
+const char *device_get_devnode(struct device *dev,
+			       mode_t *mode, const char **tmp)
 {
 	char *s;
 
 	*tmp = NULL;
 
 	/* the device type may provide a specific name */
-	if (dev->type && dev->type->nodename)
-		*tmp = dev->type->nodename(dev);
+	if (dev->type && dev->type->devnode)
+		*tmp = dev->type->devnode(dev, mode);
 	if (*tmp)
 		return *tmp;
 
 	/* the class may provide a specific name */
-	if (dev->class && dev->class->nodename)
-		*tmp = dev->class->nodename(dev);
+	if (dev->class && dev->class->devnode)
+		*tmp = dev->class->devnode(dev, mode);
 	if (*tmp)
 		return *tmp;
 

drivers/base/devtmpfs.c

@@ -6,9 +6,10 @@
  * During bootup, before any driver core device is registered,
  * devtmpfs, a tmpfs-based filesystem is created. Every driver-core
  * device which requests a device node, will add a node in this
- * filesystem. The node is named after the the name of the device,
- * or the susbsytem can provide a custom name. All devices are
- * owned by root and have a mode of 0600.
+ * filesystem.
+ * By default, all devices are named after the the name of the
+ * device, owned by root and have a default mode of 0600. Subsystems
+ * can overwrite the default setting if needed.
  */
 
 #include <linux/kernel.h>
@@ -20,6 +21,7 @@
 #include <linux/fs.h>
 #include <linux/shmem_fs.h>
 #include <linux/cred.h>
+#include <linux/sched.h>
 #include <linux/init_task.h>
 
 static struct vfsmount *dev_mnt;
@@ -134,22 +136,24 @@ int devtmpfs_create_node(struct device *dev)
 	const char *tmp = NULL;
 	const char *nodename;
 	const struct cred *curr_cred;
-	mode_t mode;
+	mode_t mode = 0;
 	struct nameidata nd;
 	struct dentry *dentry;
 	int err;
 
 	if (!dev_mnt)
 		return 0;
 
-	nodename = device_get_nodename(dev, &tmp);
+	nodename = device_get_devnode(dev, &mode, &tmp);
 	if (!nodename)
 		return -ENOMEM;
 
+	if (mode == 0)
+		mode = 0600;
 	if (is_blockdev(dev))
-		mode = S_IFBLK|0600;
+		mode |= S_IFBLK;
 	else
-		mode = S_IFCHR|0600;
+		mode |= S_IFCHR;
 
 	curr_cred = override_creds(&init_cred);
 	err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt,
@@ -165,8 +169,12 @@ int devtmpfs_create_node(struct device *dev)
 
 	dentry = lookup_create(&nd, 0);
 	if (!IS_ERR(dentry)) {
+		int umask;
+
+		umask = sys_umask(0000);
 		err = vfs_mknod(nd.path.dentry->d_inode,
 				dentry, mode, dev->devt);
+		sys_umask(umask);
 		/* mark as kernel created inode */
 		if (!err)
 			dentry->d_inode->i_private = &dev_mnt;
@@ -271,7 +279,7 @@ int devtmpfs_delete_node(struct device *dev)
 	if (!dev_mnt)
 		return 0;
 
-	nodename = device_get_nodename(dev, &tmp);
+	nodename = device_get_devnode(dev, NULL, &tmp);
 	if (!nodename)
 		return -ENOMEM;
 

drivers/block/aoe/aoechr.c

@@ -266,7 +266,7 @@ static const struct file_operations aoe_fops = {
 	.owner = THIS_MODULE,
 };
 
-static char *aoe_nodename(struct device *dev)
+static char *aoe_devnode(struct device *dev, mode_t *mode)
 {
 	return kasprintf(GFP_KERNEL, "etherd/%s", dev_name(dev));
 }
@@ -288,7 +288,7 @@ aoechr_init(void)
 		unregister_chrdev(AOE_MAJOR, "aoechr");
 		return PTR_ERR(aoe_class);
 	}
-	aoe_class->nodename = aoe_nodename;
+	aoe_class->devnode = aoe_devnode;
 
 	for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 		device_create(aoe_class, NULL,

drivers/block/pktcdvd.c

@@ -2857,7 +2857,7 @@ static struct block_device_operations pktcdvd_ops = {
 	.media_changed =	pkt_media_changed,
 };
 
-static char *pktcdvd_nodename(struct gendisk *gd)
+static char *pktcdvd_devnode(struct gendisk *gd, mode_t *mode)
 {
 	return kasprintf(GFP_KERNEL, "pktcdvd/%s", gd->disk_name);
 }
@@ -2914,7 +2914,7 @@ static int pkt_setup_dev(dev_t dev, dev_t* pkt_dev)
 	disk->fops = &pktcdvd_ops;
 	disk->flags = GENHD_FL_REMOVABLE;
 	strcpy(disk->disk_name, pd->name);
-	disk->nodename = pktcdvd_nodename;
+	disk->devnode = pktcdvd_devnode;
 	disk->private_data = pd;
 	disk->queue = blk_alloc_queue(GFP_KERNEL);
 	if (!disk->queue)
@@ -3070,7 +3070,7 @@ static const struct file_operations pkt_ctl_fops = {
 static struct miscdevice pkt_misc = {
 	.minor 		= MISC_DYNAMIC_MINOR,
 	.name  		= DRIVER_NAME,
-	.name  		= "pktcdvd/control",
+	.nodename	= "pktcdvd/control",
 	.fops  		= &pkt_ctl_fops
 };
 

drivers/char/hw_random/core.c

@@ -153,7 +153,7 @@ static const struct file_operations rng_chrdev_ops = {
 static struct miscdevice rng_miscdev = {
 	.minor		= RNG_MISCDEV_MINOR,
 	.name		= RNG_MODULE_NAME,
-	.devnode	= "hwrng",
+	.nodename	= "hwrng",
 	.fops		= &rng_chrdev_ops,
 };
 

drivers/char/mem.c

@@ -866,24 +866,25 @@ static const struct file_operations kmsg_fops = {
 
 static const struct memdev {
 	const char *name;
+	mode_t mode;
 	const struct file_operations *fops;
 	struct backing_dev_info *dev_info;
 } devlist[] = {
-	[ 1] = { "mem", &mem_fops, &directly_mappable_cdev_bdi },
+	 [1] = { "mem", 0, &mem_fops, &directly_mappable_cdev_bdi },
 #ifdef CONFIG_DEVKMEM
-	[ 2] = { "kmem", &kmem_fops, &directly_mappable_cdev_bdi },
+	 [2] = { "kmem", 0, &kmem_fops, &directly_mappable_cdev_bdi },
 #endif
-	[ 3] = {"null", &null_fops, NULL },
+	 [3] = { "null", 0666, &null_fops, NULL },
 #ifdef CONFIG_DEVPORT
-	[ 4] = { "port", &port_fops, NULL },
+	 [4] = { "port", 0, &port_fops, NULL },
 #endif
-	[ 5] = { "zero", &zero_fops, &zero_bdi },
-	[ 7] = { "full", &full_fops, NULL },
-	[ 8] = { "random", &random_fops, NULL },
-	[ 9] = { "urandom", &urandom_fops, NULL },
-	[11] = { "kmsg", &kmsg_fops, NULL },
+	 [5] = { "zero", 0666, &zero_fops, &zero_bdi },
+	 [7] = { "full", 0666, &full_fops, NULL },
+	 [8] = { "random", 0666, &random_fops, NULL },
+	 [9] = { "urandom", 0666, &urandom_fops, NULL },
+	[11] = { "kmsg", 0, &kmsg_fops, NULL },
 #ifdef CONFIG_CRASH_DUMP
-	[12] = { "oldmem", &oldmem_fops, NULL },
+	[12] = { "oldmem", 0, &oldmem_fops, NULL },
 #endif
 };
 
@@ -920,6 +921,13 @@ static const struct file_operations memory_fops = {
 	.open		= memory_open,
 };
 
+static char *mem_devnode(struct device *dev, mode_t *mode)
+{
+	if (mode && devlist[MINOR(dev->devt)].mode)
+		*mode = devlist[MINOR(dev->devt)].mode;
+	return NULL;
+}
+
 static struct class *mem_class;
 
 static int __init chr_dev_init(void)
@@ -935,6 +943,7 @@ static int __init chr_dev_init(void)
 		printk("unable to get major %d for memory devs\n", MEM_MAJOR);
 
 	mem_class = class_create(THIS_MODULE, "mem");
+	mem_class->devnode = mem_devnode;
 	for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
 		if (!devlist[minor].name)
 			continue;

drivers/char/misc.c

@@ -263,12 +263,14 @@ int misc_deregister(struct miscdevice *misc)
 EXPORT_SYMBOL(misc_register);
 EXPORT_SYMBOL(misc_deregister);
 
-static char *misc_nodename(struct device *dev)
+static char *misc_devnode(struct device *dev, mode_t *mode)
 {
 	struct miscdevice *c = dev_get_drvdata(dev);
 
-	if (c->devnode)
-		return kstrdup(c->devnode, GFP_KERNEL);
+	if (mode && c->mode)
+		*mode = c->mode;
+	if (c->nodename)
+		return kstrdup(c->nodename, GFP_KERNEL);
 	return NULL;
 }
 
@@ -287,7 +289,7 @@ static int __init misc_init(void)
 	err = -EIO;
 	if (register_chrdev(MISC_MAJOR,"misc",&misc_fops))
 		goto fail_printk;
-	misc_class->nodename = misc_nodename;
+	misc_class->devnode = misc_devnode;
 	return 0;
 
 fail_printk:

drivers/char/raw.c

@@ -261,7 +261,7 @@ static const struct file_operations raw_ctl_fops = {
 
 static struct cdev raw_cdev;
 
-static char *raw_nodename(struct device *dev)
+static char *raw_devnode(struct device *dev, mode_t *mode)
 {
 	return kasprintf(GFP_KERNEL, "raw/%s", dev_name(dev));
 }
@@ -289,7 +289,7 @@ static int __init raw_init(void)
 		ret = PTR_ERR(raw_class);
 		goto error_region;
 	}
-	raw_class->nodename = raw_nodename;
+	raw_class->devnode = raw_devnode;
 	device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl");
 
 	return 0;

drivers/char/tty_io.c

@@ -3056,11 +3056,22 @@ void __init console_init(void)
 	}
 }
 
+static char *tty_devnode(struct device *dev, mode_t *mode)
+{
+	if (!mode)
+		return NULL;
+	if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
+	    dev->devt == MKDEV(TTYAUX_MAJOR, 2))
+		*mode = 0666;
+	return NULL;
+}
+
 static int __init tty_class_init(void)
 {
 	tty_class = class_create(THIS_MODULE, "tty");
 	if (IS_ERR(tty_class))
 		return PTR_ERR(tty_class);
+	tty_class->devnode = tty_devnode;
 	return 0;
 }