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Subject[PATCH 1/2] random: Add support for architectural random hooks
Date
From: "H. Peter Anvin" <hpa@linux.intel.com>

Add support for architecture-specific hooks into either the blocking
or the nonblocking random pools. These hooks are defined to return
the number of bytes of randomness produced (similar to a read() system
call.) They could also potentialy be used to inject randomness on
demand while continuing to use the pool system, by calling a suitable
injection interface and returning 0.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "Theodore Ts'o" <tytso@mit.edu>
---
drivers/char/random.c | 26 ++++++++++++++++++++++++++
include/linux/random.h | 18 ++++++++++++++++++
2 files changed, 44 insertions(+), 0 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index d4ddeba..ca8a86c 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -416,6 +416,7 @@ struct entropy_store {
const char *name;
struct entropy_store *pull;
int limit;
+ struct get_entropy_funcs arch; /* Arch-specific shortcut */

/* read-write data: */
spinlock_t lock;
@@ -862,6 +863,15 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
__u8 tmp[EXTRACT_SIZE];
unsigned long flags;

+ if (r->arch.get_entropy_krnl) {
+ ret = r->arch.get_entropy_krnl(buf, nbytes);
+ buf += ret;
+ nbytes -= ret;
+ }
+
+ if (!nbytes)
+ return ret;
+
xfer_secondary_pool(r, nbytes);
nbytes = account(r, nbytes, min, reserved);

@@ -894,6 +904,15 @@ static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf,
ssize_t ret = 0, i;
__u8 tmp[EXTRACT_SIZE];

+ if (r->arch.get_entropy_user) {
+ ret = r->arch.get_entropy_user(buf, nbytes);
+ buf += ret;
+ nbytes -= ret;
+ }
+
+ if (!nbytes)
+ return ret;
+
xfer_secondary_pool(r, nbytes);
nbytes = account(r, nbytes, 0, 0);

@@ -954,6 +973,11 @@ static void init_std_data(struct entropy_store *r)
r->entropy_count = 0;
spin_unlock_irqrestore(&r->lock, flags);

+ if (nonblocking_pool.arch.get_entropy_krnl) {
+ nonblocking_pool.arch.get_entropy_krnl(input_pool_data,
+ sizeof input_pool_data);
+ }
+
now = ktime_get_real();
mix_pool_bytes(r, &now, sizeof(now));
mix_pool_bytes(r, utsname(), sizeof(*(utsname())));
@@ -961,6 +985,8 @@ static void init_std_data(struct entropy_store *r)

static int rand_initialize(void)
{
+ arch_setup_random_funcs(&nonblocking_pool.arch,
+ &blocking_pool.arch);
init_std_data(&input_pool);
init_std_data(&blocking_pool);
init_std_data(&nonblocking_pool);
diff --git a/include/linux/random.h b/include/linux/random.h
index fb7ab9d..12bb392 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -10,6 +10,7 @@
#include <linux/types.h>
#include <linux/ioctl.h>
#include <linux/irqnr.h>
+#include <linux/errno.h>

/* ioctl()'s for the random number generator */

@@ -75,7 +76,24 @@ extern const struct file_operations random_fops, urandom_fops;
unsigned int get_random_int(void);
unsigned long randomize_range(unsigned long start, unsigned long end, unsigned long len);

+struct get_entropy_funcs {
+ ssize_t (*get_entropy_krnl)(void *buf, size_t nbytes);
+ ssize_t (*get_entropy_user)(void __user *buf, size_t nbytes);
+};
+
+#ifdef CONFIG_ARCH_RANDOM
+void arch_setup_random_funcs(struct get_entropy_funcs *nbp,
+ struct get_entropy_funcs *bp);
+#else
+static inline void arch_setup_random_funcs(struct get_entropy_funcs *nbp,
+ struct get_entropy_funcs *bp)
+{
+ /* Nothing to do */
+}
+#endif
+
u32 random32(void);
+
void srandom32(u32 seed);

u32 prandom32(struct rnd_state *);
--
1.7.6


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