diff options
Diffstat (limited to 'drivers/char/hw_random/core.c')
| -rw-r--r-- | drivers/char/hw_random/core.c | 86 |
1 files changed, 70 insertions, 16 deletions
diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index 788da05190c..c4419ea1ab0 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -19,7 +19,7 @@ Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com> Added generic RNG API - Copyright 2006 Michael Buesch <mbuesch@freenet.de> + Copyright 2006 Michael Buesch <m@bues.ch> Copyright 2005 (c) MontaVista Software, Inc. Please read Documentation/hw_random.txt for details on use. @@ -37,10 +37,10 @@ #include <linux/kernel.h> #include <linux/fs.h> #include <linux/sched.h> -#include <linux/smp_lock.h> -#include <linux/init.h> #include <linux/miscdevice.h> #include <linux/delay.h> +#include <linux/slab.h> +#include <linux/random.h> #include <asm/uaccess.h> @@ -53,14 +53,43 @@ static struct hwrng *current_rng; static LIST_HEAD(rng_list); static DEFINE_MUTEX(rng_mutex); static int data_avail; -static u8 rng_buffer[SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES] - __cacheline_aligned; +static u8 *rng_buffer; + +static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size, + int wait); + +static size_t rng_buffer_size(void) +{ + return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES; +} + +static void add_early_randomness(struct hwrng *rng) +{ + unsigned char bytes[16]; + int bytes_read; + + /* + * Currently only virtio-rng cannot return data during device + * probe, and that's handled in virtio-rng.c itself. If there + * are more such devices, this call to rng_get_data can be + * made conditional here instead of doing it per-device. + */ + bytes_read = rng_get_data(rng, bytes, sizeof(bytes), 1); + if (bytes_read > 0) + add_device_randomness(bytes, bytes_read); +} static inline int hwrng_init(struct hwrng *rng) { - if (!rng->init) - return 0; - return rng->init(rng); + if (rng->init) { + int ret; + + ret = rng->init(rng); + if (ret) + return ret; + } + add_early_randomness(rng); + return 0; } static inline void hwrng_cleanup(struct hwrng *rng) @@ -117,7 +146,7 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf, if (!data_avail) { bytes_read = rng_get_data(current_rng, rng_buffer, - sizeof(rng_buffer), + rng_buffer_size(), !(filp->f_flags & O_NONBLOCK)); if (bytes_read < 0) { err = bytes_read; @@ -298,7 +327,6 @@ err_misc_dereg: int hwrng_register(struct hwrng *rng) { - int must_register_misc; int err = -EINVAL; struct hwrng *old_rng, *tmp; @@ -308,6 +336,14 @@ int hwrng_register(struct hwrng *rng) mutex_lock(&rng_mutex); + /* kmalloc makes this safe for virt_to_page() in virtio_rng.c */ + err = -ENOMEM; + if (!rng_buffer) { + rng_buffer = kmalloc(rng_buffer_size(), GFP_KERNEL); + if (!rng_buffer) + goto out_unlock; + } + /* Must not register two RNGs with the same name. */ err = -EEXIST; list_for_each_entry(tmp, &rng_list, list) { @@ -315,7 +351,6 @@ int hwrng_register(struct hwrng *rng) goto out_unlock; } - must_register_misc = (current_rng == NULL); old_rng = current_rng; if (!old_rng) { err = hwrng_init(rng); @@ -324,18 +359,28 @@ int hwrng_register(struct hwrng *rng) current_rng = rng; } err = 0; - if (must_register_misc) { + if (!old_rng) { err = register_miscdev(); if (err) { - if (!old_rng) { - hwrng_cleanup(rng); - current_rng = NULL; - } + hwrng_cleanup(rng); + current_rng = NULL; goto out_unlock; } } INIT_LIST_HEAD(&rng->list); list_add_tail(&rng->list, &rng_list); + + if (old_rng && !rng->init) { + /* + * Use a new device's input to add some randomness to + * the system. If this rng device isn't going to be + * used right away, its init function hasn't been + * called yet; so only use the randomness from devices + * that don't need an init callback. + */ + add_early_randomness(rng); + } + out_unlock: mutex_unlock(&rng_mutex); out: @@ -368,6 +413,15 @@ void hwrng_unregister(struct hwrng *rng) } EXPORT_SYMBOL_GPL(hwrng_unregister); +static void __exit hwrng_exit(void) +{ + mutex_lock(&rng_mutex); + BUG_ON(current_rng); + kfree(rng_buffer); + mutex_unlock(&rng_mutex); +} + +module_exit(hwrng_exit); MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver"); MODULE_LICENSE("GPL"); |