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| author | Torsten Duwe <duwe@lst.de> | 2014-06-14 23:48:41 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2014-07-15 04:49:40 -0400 |
| commit | 0f734e6e768b4b66737b3d3e13f1769a12ecff86 (patch) | |
| tree | 637eb77455b97fa9385a442a25406443a6bceda7 | |
| parent | be4000bc4644d027c519b6361f5ae3bbfc52c347 (diff) | |
| download | talos-obmc-linux-0f734e6e768b4b66737b3d3e13f1769a12ecff86.tar.gz talos-obmc-linux-0f734e6e768b4b66737b3d3e13f1769a12ecff86.zip | |
hwrng: add per-device entropy derating
This patch introduces a derating factor to struct hwrng for
the random bits going into the kernel input pool, and a common
default derating for drivers which do not specify one.
Signed-off-by: Torsten Duwe <duwe@suse.de>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Acked-by: H. Peter Anvin <hpa@zytor.com>
| -rw-r--r-- | drivers/char/hw_random/core.c | 11 | ||||
| -rw-r--r-- | include/linux/hw_random.h | 3 |
2 files changed, 13 insertions, 1 deletions
diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index 48b3c812b9ec..3aaf97c774f1 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -56,11 +56,15 @@ static LIST_HEAD(rng_list); static DEFINE_MUTEX(rng_mutex); static int data_avail; static u8 *rng_buffer, *rng_fillbuf; -static unsigned short current_quality = 700; /* an arbitrary 70% */ +static unsigned short current_quality; +static unsigned short default_quality; /* = 0; default to "off" */ module_param(current_quality, ushort, 0644); MODULE_PARM_DESC(current_quality, "current hwrng entropy estimation per mill"); +module_param(default_quality, ushort, 0644); +MODULE_PARM_DESC(default_quality, + "default entropy content of hwrng per mill"); static void start_khwrngd(void); @@ -79,6 +83,11 @@ static inline int hwrng_init(struct hwrng *rng) return err; } + current_quality = rng->quality ? : default_quality; + current_quality &= 1023; + + if (current_quality == 0 && hwrng_fill) + kthread_stop(hwrng_fill); if (current_quality > 0 && !hwrng_fill) start_khwrngd(); diff --git a/include/linux/hw_random.h b/include/linux/hw_random.h index 3f075ff00411..914bb08cd738 100644 --- a/include/linux/hw_random.h +++ b/include/linux/hw_random.h @@ -29,6 +29,8 @@ * @read: New API. drivers can fill up to max bytes of data * into the buffer. The buffer is aligned for any type. * @priv: Private data, for use by the RNG driver. + * @quality: Estimation of true entropy in RNG's bitstream + * (per mill). */ struct hwrng { const char *name; @@ -38,6 +40,7 @@ struct hwrng { int (*data_read)(struct hwrng *rng, u32 *data); int (*read)(struct hwrng *rng, void *data, size_t max, bool wait); unsigned long priv; + unsigned short quality; /* internal. */ struct list_head list; |
