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>

1 files changed, 19 insertions, 10 deletions

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 0491cdf63f2a..0aede1d6a9ea 100644
--- a/drivers/char/mem.c
+++ b/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;