diff options
Diffstat (limited to 'drivers/char/hw_random/core.c')
| -rw-r--r-- | drivers/char/hw_random/core.c | 130 |
1 files changed, 53 insertions, 77 deletions
diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index f34d356fe2c0..96d7fe41b373 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -15,19 +15,21 @@ #include <linux/err.h> #include <linux/fs.h> #include <linux/hw_random.h> -#include <linux/random.h> #include <linux/kernel.h> #include <linux/kthread.h> -#include <linux/sched/signal.h> #include <linux/miscdevice.h> #include <linux/module.h> #include <linux/random.h> #include <linux/sched.h> +#include <linux/sched/signal.h> #include <linux/slab.h> +#include <linux/string.h> #include <linux/uaccess.h> #define RNG_MODULE_NAME "hw_random" +#define RNG_BUFFER_SIZE (SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES) + static struct hwrng *current_rng; /* the current rng has been explicitly chosen by user via sysfs */ static int cur_rng_set_by_user; @@ -59,20 +61,7 @@ static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size, static size_t rng_buffer_size(void) { - return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES; -} - -static void add_early_randomness(struct hwrng *rng) -{ - int bytes_read; - - mutex_lock(&reading_mutex); - bytes_read = rng_get_data(rng, rng_fillbuf, 32, 0); - mutex_unlock(&reading_mutex); - if (bytes_read > 0) { - size_t entropy = bytes_read * 8 * rng->quality / 1024; - add_hwgenerator_randomness(rng_fillbuf, bytes_read, entropy, false); - } + return RNG_BUFFER_SIZE; } static inline void cleanup_rng(struct kref *kref) @@ -172,7 +161,6 @@ static int hwrng_init(struct hwrng *rng) reinit_completion(&rng->cleanup_done); skip_init: - rng->quality = min_t(u16, min_t(u16, default_quality, 1024), rng->quality ?: 1024); current_quality = rng->quality; /* obsolete */ return 0; @@ -193,8 +181,15 @@ static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size, int present; BUG_ON(!mutex_is_locked(&reading_mutex)); - if (rng->read) - return rng->read(rng, (void *)buffer, size, wait); + if (rng->read) { + int err; + + err = rng->read(rng, buffer, size, wait); + if (WARN_ON_ONCE(err > 0 && err > size)) + err = size; + + return err; + } if (rng->data_present) present = rng->data_present(rng, wait); @@ -210,6 +205,7 @@ static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size, static ssize_t rng_dev_read(struct file *filp, char __user *buf, size_t size, loff_t *offp) { + u8 buffer[RNG_BUFFER_SIZE]; ssize_t ret = 0; int err = 0; int bytes_read, len; @@ -237,34 +233,37 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf, if (bytes_read < 0) { err = bytes_read; goto out_unlock_reading; + } else if (bytes_read == 0 && + (filp->f_flags & O_NONBLOCK)) { + err = -EAGAIN; + goto out_unlock_reading; } + data_avail = bytes_read; } - if (!data_avail) { - if (filp->f_flags & O_NONBLOCK) { - err = -EAGAIN; - goto out_unlock_reading; - } - } else { - len = data_avail; + len = data_avail; + if (len) { if (len > size) len = size; data_avail -= len; - if (copy_to_user(buf + ret, rng_buffer + data_avail, - len)) { + memcpy(buffer, rng_buffer + data_avail, len); + } + mutex_unlock(&reading_mutex); + put_rng(rng); + + if (len) { + if (copy_to_user(buf + ret, buffer, len)) { err = -EFAULT; - goto out_unlock_reading; + goto out; } size -= len; ret += len; } - mutex_unlock(&reading_mutex); - put_rng(rng); if (need_resched()) schedule_timeout_interruptible(1); @@ -275,6 +274,7 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf, } } out: + memzero_explicit(buffer, sizeof(buffer)); return ret ? : err; out_unlock_reading: @@ -333,15 +333,17 @@ static ssize_t rng_current_store(struct device *dev, const char *buf, size_t len) { int err; - struct hwrng *rng, *old_rng, *new_rng; + struct hwrng *rng, *new_rng; err = mutex_lock_interruptible(&rng_mutex); if (err) return -ERESTARTSYS; - old_rng = current_rng; if (sysfs_streq(buf, "")) { err = enable_best_rng(); + } else if (sysfs_streq(buf, "none")) { + cur_rng_set_by_user = 1; + drop_current_rng(); } else { list_for_each_entry(rng, &rng_list, list) { if (sysfs_streq(rng->name, buf)) { @@ -355,11 +357,8 @@ static ssize_t rng_current_store(struct device *dev, new_rng = get_current_rng_nolock(); mutex_unlock(&rng_mutex); - if (new_rng) { - if (new_rng != old_rng) - add_early_randomness(new_rng); + if (new_rng) put_rng(new_rng); - } return err ? : len; } @@ -375,7 +374,7 @@ static ssize_t rng_current_show(struct device *dev, if (IS_ERR(rng)) return PTR_ERR(rng); - ret = snprintf(buf, PAGE_SIZE, "%s\n", rng ? rng->name : "none"); + ret = sysfs_emit(buf, "%s\n", rng ? rng->name : "none"); put_rng(rng); return ret; @@ -396,7 +395,7 @@ static ssize_t rng_available_show(struct device *dev, strlcat(buf, rng->name, PAGE_SIZE); strlcat(buf, " ", PAGE_SIZE); } - strlcat(buf, "\n", PAGE_SIZE); + strlcat(buf, "none\n", PAGE_SIZE); mutex_unlock(&rng_mutex); return strlen(buf); @@ -480,16 +479,6 @@ static struct attribute *rng_dev_attrs[] = { ATTRIBUTE_GROUPS(rng_dev); -static void __exit unregister_miscdev(void) -{ - misc_deregister(&rng_miscdev); -} - -static int __init register_miscdev(void) -{ - return misc_register(&rng_miscdev); -} - static int hwrng_fillfn(void *unused) { size_t entropy, entropy_credit = 0; /* in 1/1024 of a bit */ @@ -537,7 +526,6 @@ int hwrng_register(struct hwrng *rng) { int err = -EINVAL; struct hwrng *tmp; - bool is_new_current = false; if (!rng->name || (!rng->data_read && !rng->read)) goto out; @@ -556,8 +544,11 @@ int hwrng_register(struct hwrng *rng) complete(&rng->cleanup_done); init_completion(&rng->dying); - if (!current_rng || - (!cur_rng_set_by_user && rng->quality > current_rng->quality)) { + /* Adjust quality field to always have a proper value */ + rng->quality = min3(default_quality, 1024, rng->quality ?: 1024); + + if (!cur_rng_set_by_user && + (!current_rng || rng->quality > current_rng->quality)) { /* * Set new rng as current as the new rng source * provides better entropy quality and was not @@ -566,25 +557,8 @@ int hwrng_register(struct hwrng *rng) err = set_current_rng(rng); if (err) goto out_unlock; - /* to use current_rng in add_early_randomness() we need - * to take a ref - */ - is_new_current = true; - kref_get(&rng->ref); } mutex_unlock(&rng_mutex); - if (is_new_current || !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 by set_current_rng(); so only use the - * randomness from devices that don't need an init callback - */ - add_early_randomness(rng); - } - if (is_new_current) - put_rng(rng); return 0; out_unlock: mutex_unlock(&rng_mutex); @@ -595,12 +569,11 @@ EXPORT_SYMBOL_GPL(hwrng_register); void hwrng_unregister(struct hwrng *rng) { - struct hwrng *old_rng, *new_rng; + struct hwrng *new_rng; int err; mutex_lock(&rng_mutex); - old_rng = current_rng; list_del(&rng->list); complete_all(&rng->dying); if (current_rng == rng) { @@ -619,11 +592,8 @@ void hwrng_unregister(struct hwrng *rng) } else mutex_unlock(&rng_mutex); - if (new_rng) { - if (old_rng != new_rng) - add_early_randomness(new_rng); + if (new_rng) put_rng(new_rng); - } wait_for_completion(&rng->cleanup_done); } @@ -679,6 +649,12 @@ long hwrng_msleep(struct hwrng *rng, unsigned int msecs) } EXPORT_SYMBOL_GPL(hwrng_msleep); +long hwrng_yield(struct hwrng *rng) +{ + return wait_for_completion_interruptible_timeout(&rng->dying, 1); +} +EXPORT_SYMBOL_GPL(hwrng_yield); + static int __init hwrng_modinit(void) { int ret; @@ -694,7 +670,7 @@ static int __init hwrng_modinit(void) return -ENOMEM; } - ret = register_miscdev(); + ret = misc_register(&rng_miscdev); if (ret) { kfree(rng_fillbuf); kfree(rng_buffer); @@ -711,7 +687,7 @@ static void __exit hwrng_modexit(void) kfree(rng_fillbuf); mutex_unlock(&rng_mutex); - unregister_miscdev(); + misc_deregister(&rng_miscdev); } fs_initcall(hwrng_modinit); /* depends on misc_register() */ |