From e454cea20bdcff10ee698d11b8882662a0153a47 Mon Sep 17 00:00:00 2001 From: Kay Sievers Date: Fri, 18 Sep 2009 23:01:12 +0200 Subject: 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 Signed-off-by: Greg Kroah-Hartman --- drivers/char/mem.c | 29 +++++++++++++++++++---------- 1 file changed, 19 insertions(+), 10 deletions(-) (limited to 'drivers/char/mem.c') diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 0491cdf63f2..0aede1d6a9e 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; -- cgit v1.2.3 From bb521c5de070b86a1e049e2dbf62328f717ff1e8 Mon Sep 17 00:00:00 2001 From: Nikanth Karthikesan Date: Wed, 23 Sep 2009 15:57:09 -0700 Subject: /dev/zero: avoid repeated access_ok() checks In read_zero, we check for access_ok() once for the count bytes. It is unnecessarily checked again in clear_user. Use __clear_user, which does not check for access_ok(). Signed-off-by: Nikanth Karthikesan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/char/mem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/char/mem.c') diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 0aede1d6a9e..6c8b65d069e 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -690,7 +690,7 @@ static ssize_t read_zero(struct file * file, char __user * buf, if (chunk > PAGE_SIZE) chunk = PAGE_SIZE; /* Just for latency reasons */ - unwritten = clear_user(buf, chunk); + unwritten = __clear_user(buf, chunk); written += chunk - unwritten; if (unwritten) break; -- cgit v1.2.3