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author | Ralph Wuerthner <rwuerthn@de.ibm.com> | 2008-04-17 07:46:15 +0200 |
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committer | Heiko Carstens <heiko.carstens@de.ibm.com> | 2008-04-17 07:47:02 +0200 |
commit | 2f7c8bd6dc6540aa3275c0ad9f657401985c00e9 (patch) | |
tree | 12cb12d661424d332ad960113c8849b3579e7e6a /drivers/s390/crypto/zcrypt_api.c | |
parent | 893f11286644780fc7d6d415e537644da7bdaaf8 (diff) | |
download | linux-3.10-2f7c8bd6dc6540aa3275c0ad9f657401985c00e9.tar.gz linux-3.10-2f7c8bd6dc6540aa3275c0ad9f657401985c00e9.tar.bz2 linux-3.10-2f7c8bd6dc6540aa3275c0ad9f657401985c00e9.zip |
[S390] zcrypt: add support for large random numbers
This patch allows user space applications to access large amounts of
truly random data. The random data source is the build-in hardware
random number generator on the CEX2C cards.
Signed-off-by: Ralph Wuerthner <rwuerthn@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Diffstat (limited to 'drivers/s390/crypto/zcrypt_api.c')
-rw-r--r-- | drivers/s390/crypto/zcrypt_api.c | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/drivers/s390/crypto/zcrypt_api.c b/drivers/s390/crypto/zcrypt_api.c index e3625a47a59..b2740ff2e61 100644 --- a/drivers/s390/crypto/zcrypt_api.c +++ b/drivers/s390/crypto/zcrypt_api.c @@ -36,6 +36,7 @@ #include <linux/compat.h> #include <asm/atomic.h> #include <asm/uaccess.h> +#include <linux/hw_random.h> #include "zcrypt_api.h" @@ -52,6 +53,9 @@ static LIST_HEAD(zcrypt_device_list); static int zcrypt_device_count = 0; static atomic_t zcrypt_open_count = ATOMIC_INIT(0); +static int zcrypt_rng_device_add(void); +static void zcrypt_rng_device_remove(void); + /** * Device attributes common for all crypto devices. */ @@ -216,6 +220,22 @@ int zcrypt_device_register(struct zcrypt_device *zdev) __zcrypt_increase_preference(zdev); zcrypt_device_count++; spin_unlock_bh(&zcrypt_device_lock); + if (zdev->ops->rng) { + rc = zcrypt_rng_device_add(); + if (rc) + goto out_unregister; + } + return 0; + +out_unregister: + spin_lock_bh(&zcrypt_device_lock); + zcrypt_device_count--; + list_del_init(&zdev->list); + spin_unlock_bh(&zcrypt_device_lock); + sysfs_remove_group(&zdev->ap_dev->device.kobj, + &zcrypt_device_attr_group); + put_device(&zdev->ap_dev->device); + zcrypt_device_put(zdev); out: return rc; } @@ -226,6 +246,8 @@ EXPORT_SYMBOL(zcrypt_device_register); */ void zcrypt_device_unregister(struct zcrypt_device *zdev) { + if (zdev->ops->rng) + zcrypt_rng_device_remove(); spin_lock_bh(&zcrypt_device_lock); zcrypt_device_count--; list_del_init(&zdev->list); @@ -427,6 +449,37 @@ static long zcrypt_send_cprb(struct ica_xcRB *xcRB) return -ENODEV; } +static long zcrypt_rng(char *buffer) +{ + struct zcrypt_device *zdev; + int rc; + + spin_lock_bh(&zcrypt_device_lock); + list_for_each_entry(zdev, &zcrypt_device_list, list) { + if (!zdev->online || !zdev->ops->rng) + continue; + zcrypt_device_get(zdev); + get_device(&zdev->ap_dev->device); + zdev->request_count++; + __zcrypt_decrease_preference(zdev); + if (try_module_get(zdev->ap_dev->drv->driver.owner)) { + spin_unlock_bh(&zcrypt_device_lock); + rc = zdev->ops->rng(zdev, buffer); + spin_lock_bh(&zcrypt_device_lock); + module_put(zdev->ap_dev->drv->driver.owner); + } else + rc = -EAGAIN; + zdev->request_count--; + __zcrypt_increase_preference(zdev); + put_device(&zdev->ap_dev->device); + zcrypt_device_put(zdev); + spin_unlock_bh(&zcrypt_device_lock); + return rc; + } + spin_unlock_bh(&zcrypt_device_lock); + return -ENODEV; +} + static void zcrypt_status_mask(char status[AP_DEVICES]) { struct zcrypt_device *zdev; @@ -1041,6 +1094,73 @@ out: return count; } +static int zcrypt_rng_device_count; +static u32 *zcrypt_rng_buffer; +static int zcrypt_rng_buffer_index; +static DEFINE_MUTEX(zcrypt_rng_mutex); + +static int zcrypt_rng_data_read(struct hwrng *rng, u32 *data) +{ + int rc; + + /** + * We don't need locking here because the RNG API guarantees serialized + * read method calls. + */ + if (zcrypt_rng_buffer_index == 0) { + rc = zcrypt_rng((char *) zcrypt_rng_buffer); + if (rc < 0) + return -EIO; + zcrypt_rng_buffer_index = rc / sizeof *data; + } + *data = zcrypt_rng_buffer[--zcrypt_rng_buffer_index]; + return sizeof *data; +} + +static struct hwrng zcrypt_rng_dev = { + .name = "zcrypt", + .data_read = zcrypt_rng_data_read, +}; + +static int zcrypt_rng_device_add(void) +{ + int rc = 0; + + mutex_lock(&zcrypt_rng_mutex); + if (zcrypt_rng_device_count == 0) { + zcrypt_rng_buffer = (u32 *) get_zeroed_page(GFP_KERNEL); + if (!zcrypt_rng_buffer) { + rc = -ENOMEM; + goto out; + } + zcrypt_rng_buffer_index = 0; + rc = hwrng_register(&zcrypt_rng_dev); + if (rc) + goto out_free; + zcrypt_rng_device_count = 1; + } else + zcrypt_rng_device_count++; + mutex_unlock(&zcrypt_rng_mutex); + return 0; + +out_free: + free_page((unsigned long) zcrypt_rng_buffer); +out: + mutex_unlock(&zcrypt_rng_mutex); + return rc; +} + +static void zcrypt_rng_device_remove(void) +{ + mutex_lock(&zcrypt_rng_mutex); + zcrypt_rng_device_count--; + if (zcrypt_rng_device_count == 0) { + hwrng_unregister(&zcrypt_rng_dev); + free_page((unsigned long) zcrypt_rng_buffer); + } + mutex_unlock(&zcrypt_rng_mutex); +} + /** * The module initialization code. */ |