diff options
Diffstat (limited to 'drivers/char/hw_random/core.c')
| -rw-r--r-- | drivers/char/hw_random/core.c | 55 |
1 files changed, 44 insertions, 11 deletions
diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index a0f7724852e..c4419ea1ab0 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -37,10 +37,10 @@ #include <linux/kernel.h> #include <linux/fs.h> #include <linux/sched.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> @@ -55,16 +55,41 @@ static DEFINE_MUTEX(rng_mutex); static int data_avail; 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) @@ -302,7 +327,6 @@ err_misc_dereg: int hwrng_register(struct hwrng *rng) { - int must_register_misc; int err = -EINVAL; struct hwrng *old_rng, *tmp; @@ -327,7 +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); @@ -336,18 +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: |