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authorTorsten Duwe <duwe@lst.de>2014-06-14 23:48:41 -0400
committerTheodore Ts'o <tytso@mit.edu>2014-07-15 04:49:40 -0400
commit0f734e6e768b4b66737b3d3e13f1769a12ecff86 (patch)
tree637eb77455b97fa9385a442a25406443a6bceda7
parentbe4000bc4644d027c519b6361f5ae3bbfc52c347 (diff)
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.c11
-rw-r--r--include/linux/hw_random.h3
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);
56static DEFINE_MUTEX(rng_mutex); 56static DEFINE_MUTEX(rng_mutex);
57static int data_avail; 57static int data_avail;
58static u8 *rng_buffer, *rng_fillbuf; 58static u8 *rng_buffer, *rng_fillbuf;
59static unsigned short current_quality = 700; /* an arbitrary 70% */ 59static unsigned short current_quality;
60static unsigned short default_quality; /* = 0; default to "off" */
60 61
61module_param(current_quality, ushort, 0644); 62module_param(current_quality, ushort, 0644);
62MODULE_PARM_DESC(current_quality, 63MODULE_PARM_DESC(current_quality,
63 "current hwrng entropy estimation per mill"); 64 "current hwrng entropy estimation per mill");
65module_param(default_quality, ushort, 0644);
66MODULE_PARM_DESC(default_quality,
67 "default entropy content of hwrng per mill");
64 68
65static void start_khwrngd(void); 69static void start_khwrngd(void);
66 70
@@ -79,6 +83,11 @@ static inline int hwrng_init(struct hwrng *rng)
79 return err; 83 return err;
80 } 84 }
81 85
86 current_quality = rng->quality ? : default_quality;
87 current_quality &= 1023;
88
89 if (current_quality == 0 && hwrng_fill)
90 kthread_stop(hwrng_fill);
82 if (current_quality > 0 && !hwrng_fill) 91 if (current_quality > 0 && !hwrng_fill)
83 start_khwrngd(); 92 start_khwrngd();
84 93
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 @@
29 * @read: New API. drivers can fill up to max bytes of data 29 * @read: New API. drivers can fill up to max bytes of data
30 * into the buffer. The buffer is aligned for any type. 30 * into the buffer. The buffer is aligned for any type.
31 * @priv: Private data, for use by the RNG driver. 31 * @priv: Private data, for use by the RNG driver.
32 * @quality: Estimation of true entropy in RNG's bitstream
33 * (per mill).
32 */ 34 */
33struct hwrng { 35struct hwrng {
34 const char *name; 36 const char *name;
@@ -38,6 +40,7 @@ struct hwrng {
38 int (*data_read)(struct hwrng *rng, u32 *data); 40 int (*data_read)(struct hwrng *rng, u32 *data);
39 int (*read)(struct hwrng *rng, void *data, size_t max, bool wait); 41 int (*read)(struct hwrng *rng, void *data, size_t max, bool wait);
40 unsigned long priv; 42 unsigned long priv;
43 unsigned short quality;
41 44
42 /* internal. */ 45 /* internal. */
43 struct list_head list; 46 struct list_head list;