From: Matt Mackall <mpm@selenic.com>
Clean up buffer usage for SHA and reseed. This makes the code more readable
and reduces worst-case stack usage.
Signed-off-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/drivers/char/random.c | 36 +++++++++++++++++++-----------------
1 files changed, 19 insertions(+), 17 deletions(-)
diff -puN drivers/char/random.c~random-pt3-clean-up-hash-buffering drivers/char/random.c
--- 25/drivers/char/random.c~random-pt3-clean-up-hash-buffering Wed Jan 19 15:30:02 2005
+++ 25-akpm/drivers/char/random.c Wed Jan 19 15:30:02 2005
@@ -255,6 +255,7 @@
#define INPUT_POOL_WORDS 128
#define OUTPUT_POOL_WORDS 32
#define BATCH_ENTROPY_SIZE 256
+#define SEC_XFER_SIZE 512
/*
* The minimum number of bits of entropy before we wake up a read on
@@ -813,6 +814,7 @@ EXPORT_SYMBOL(add_disk_randomness);
*/
#define HASH_BUFFER_SIZE 5
+#define EXTRACT_SIZE 10
#define HASH_EXTRA_SIZE 80
/* Various size/speed tradeoffs are available. Choose 0..3. */
@@ -1048,9 +1050,6 @@ static void sha_transform(__u32 digest[8
*
*********************************************************************/
-#define TMP_BUF_SIZE (HASH_BUFFER_SIZE + HASH_EXTRA_SIZE)
-#define SEC_XFER_SIZE (TMP_BUF_SIZE*4)
-
static ssize_t extract_entropy(struct entropy_store *r, void * buf,
size_t nbytes, int min, int rsvd);
@@ -1059,13 +1058,14 @@ static ssize_t extract_entropy(struct en
* from the primary pool to the secondary extraction pool. We make
* sure we pull enough for a 'catastrophic reseed'.
*/
-static void xfer_secondary_pool(struct entropy_store *r,
- size_t nbytes, __u32 *tmp)
+static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
{
+ __u32 tmp[OUTPUT_POOL_WORDS];
+
if (r->pull && r->entropy_count < nbytes * 8 &&
r->entropy_count < r->poolinfo->POOLBITS) {
int bytes = max_t(int, random_read_wakeup_thresh / 8,
- min_t(int, nbytes, TMP_BUF_SIZE));
+ min_t(int, nbytes, sizeof(tmp)));
int rsvd = r->limit ? 0 : random_read_wakeup_thresh/4;
DEBUG_ENT("going to reseed %s with %d bits "
@@ -1129,10 +1129,10 @@ static size_t account(struct entropy_sto
return nbytes;
}
-static void extract_buf(struct entropy_store *r, __u32 *buf)
+static void extract_buf(struct entropy_store *r, __u8 *out)
{
int i, x;
- __u32 data[16];
+ __u32 data[16], buf[85];
/* Hash the pool to get the output */
buf[0] = 0x67452301;
@@ -1151,7 +1151,7 @@ static void extract_buf(struct entropy_s
*/
for (i = 0, x = 0; i < r->poolinfo->poolwords; i += 16, x+=2) {
sha_transform(buf, r->pool+i);
- add_entropy_words(r, &buf[x%HASH_BUFFER_SIZE], 1);
+ add_entropy_words(r, &buf[x % 5], 1);
}
/*
@@ -1159,7 +1159,7 @@ static void extract_buf(struct entropy_s
* portion of the pool while mixing, and hash one
* final time.
*/
- __add_entropy_words(r, &buf[x%HASH_BUFFER_SIZE], 1, data);
+ __add_entropy_words(r, &buf[x % 5], 1, data);
sha_transform(buf, data);
/*
@@ -1170,21 +1170,23 @@ static void extract_buf(struct entropy_s
buf[0] ^= buf[3];
buf[1] ^= buf[4];
buf[0] ^= rol32(buf[3], 16);
+ memcpy(out, buf, EXTRACT_SIZE);
+ memset(buf, 0, sizeof(buf));
}
static ssize_t extract_entropy(struct entropy_store *r, void * buf,
size_t nbytes, int min, int reserved)
{
ssize_t ret = 0, i;
- __u32 tmp[TMP_BUF_SIZE];
+ __u8 tmp[EXTRACT_SIZE];
- xfer_secondary_pool(r, nbytes, tmp);
+ xfer_secondary_pool(r, nbytes);
nbytes = account(r, nbytes, min, reserved);
while (nbytes) {
extract_buf(r, tmp);
- i = min(nbytes, HASH_BUFFER_SIZE * sizeof(__u32) / 2);
- memcpy(buf, (__u8 const *)tmp, i);
+ i = min_t(int, nbytes, EXTRACT_SIZE);
+ memcpy(buf, tmp, i);
nbytes -= i;
buf += i;
ret += i;
@@ -1200,9 +1202,9 @@ static ssize_t extract_entropy_user(stru
size_t nbytes)
{
ssize_t ret = 0, i;
- __u32 tmp[TMP_BUF_SIZE];
+ __u8 tmp[EXTRACT_SIZE];
- xfer_secondary_pool(r, nbytes, tmp);
+ xfer_secondary_pool(r, nbytes);
nbytes = account(r, nbytes, 0, 0);
while (nbytes) {
@@ -1216,7 +1218,7 @@ static ssize_t extract_entropy_user(stru
}
extract_buf(r, tmp);
- i = min(nbytes, HASH_BUFFER_SIZE * sizeof(__u32) / 2);
+ i = min_t(int, nbytes, EXTRACT_SIZE);
if (copy_to_user(buf, tmp, i)) {
ret = -EFAULT;
break;
_