[PATCH 3/7] Initialise pools randomly if CONFIG_RANDOM_INIT=y

Sandy Harris
2015-11-07T14:30:56Z

Signed-off-by: Sandy Harris <sandyinchina@gmail.com>
---
drivers/char/random.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 46 insertions(+), 4 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index d0da5d8..e222e0f 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -231,7 +231,7 @@
* not be attributed to the Phil, Colin, or any of authors of PGP.
*
* Further background information on this topic may be obtained from
- * RFC 1750, "Randomness Recommendations for Security", by Donald
+ * RFC 4086, "Randomness Requirements for Security", by Donald
* Eastlake, Steve Crocker, and Jeff Schiller.
*/

@@ -275,13 +275,19 @@
/*
* Configuration information
*/
+#ifdef CONFIG_RANDOM_INIT
+
+#include <generated/random_init.h>
+
+#else
#define INPUT_POOL_SHIFT 12
#define INPUT_POOL_WORDS (1 << (INPUT_POOL_SHIFT-5))
#define OUTPUT_POOL_SHIFT 10
#define OUTPUT_POOL_WORDS (1 << (OUTPUT_POOL_SHIFT-5))
-#define SEC_XFER_SIZE 512
-#define EXTRACT_SIZE 10
+#endif

+#define EXTRACT_SIZE 10
+#define SEC_XFER_SIZE 512
#define DEBUG_RANDOM_BOOT 0

#define LONGS(x) (((x) + sizeof(unsigned long) - 1)/sizeof(unsigned long))
@@ -296,6 +302,27 @@
#define ENTROPY_SHIFT 3
#define ENTROPY_BITS(r) ((r)->entropy_count >> ENTROPY_SHIFT)

+/* sanity checks */
+
+#if ((ENTROPY_SHIFT+INPUT_POOL_SHIFT) >= 16)
+#ifndef CONFIG_64BIT
+#error *_SHIFT values problematic for credit_entropy_bits()
+#endif
+#endif
+
+#if ((INPUT_POOL_WORDS%16) || (OUTPUT_POOL_WORDS%16))
+#error Pool size not divisible by 16, which code assumes
+#endif
+
+#if (INPUT_POOL_WORDS < 32)
+#error Input pool less than a quarter of default size
+#endif
+
+#if (INPUT_POOL_WORDS < OUTPUT_POOL_WORDS)
+#error Strange configuration, input pool smalller than output
+#endif
+
+
/*
* The minimum number of bits of entropy before we wake up a read on
* /dev/random. Should be enough to do a significant reseed.
@@ -442,16 +469,23 @@ struct entropy_store {
};

static void push_to_pool(struct work_struct *work);
+
+#ifndef CONFIG_RANDOM_INIT
static __u32 input_pool_data[INPUT_POOL_WORDS];
static __u32 blocking_pool_data[OUTPUT_POOL_WORDS];
static __u32 nonblocking_pool_data[OUTPUT_POOL_WORDS];
+#endif

static struct entropy_store input_pool = {
.poolinfo = &poolinfo_table[0],
.name = "input",
.limit = 1,
.lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
- .pool = input_pool_data
+#ifdef CONFIG_RANDOM_INIT
+ .pool = pools,
+#else
+ .pool = input_pool_data,
+#endif
};

static struct entropy_store blocking_pool = {
@@ -460,7 +494,11 @@ static struct entropy_store blocking_pool = {
.limit = 1,
.pull = &input_pool,
.lock = __SPIN_LOCK_UNLOCKED(blocking_pool.lock),
+#ifdef CONFIG_RANDOM_INIT
+ .pool = pools + INPUT_POOL_WORDS,
+#else
.pool = blocking_pool_data,
+#endif
.push_work = __WORK_INITIALIZER(blocking_pool.push_work,
push_to_pool),
};
@@ -470,7 +508,11 @@ static struct entropy_store nonblocking_pool = {
.name = "nonblocking",
.pull = &input_pool,
.lock = __SPIN_LOCK_UNLOCKED(nonblocking_pool.lock),
+#ifdef CONFIG_RANDOM_INIT
+ .pool = pools + INPUT_POOL_WORDS + OUTPUT_POOL_WORDS,
+#else
.pool = nonblocking_pool_data,
+#endif
.push_work = __WORK_INITIALIZER(nonblocking_pool.push_work,
push_to_pool),
};
--
2.5.0