From: Matt Mackall <mpm@selenic.com>
To: Andrew Morton <akpm@osdl.org>, "Theodore Ts'o" <tytso@mit.edu>
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH 11/12] random pt3: Clean up hash buffering
Date: Wed, 19 Jan 2005 00:17:24 -0800 [thread overview]
Message-ID: <12.64403262@selenic.com> (raw)
In-Reply-To: <11.64403262@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>
Index: rnd/drivers/char/random.c
===================================================================
--- rnd.orig/drivers/char/random.c 2005-01-18 10:42:39.078612373 -0800
+++ rnd/drivers/char/random.c 2005-01-18 10:45:13.176966505 -0800
@@ -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 @@
*/
#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 @@
*
*********************************************************************/
-#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 @@
* 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 @@
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 @@
*/
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 @@
* 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 @@
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 @@
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 @@
}
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;
next prev parent reply other threads:[~2005-01-19 8:43 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-01-19 8:17 [PATCH 0/12] random pt3: More core and accounting cleanups Matt Mackall
2005-01-19 8:17 ` [PATCH 1/12] random pt3: More meaningful pool names Matt Mackall
2005-01-19 8:17 ` [PATCH 2/12] random pt3: Static allocation of pools Matt Mackall
2005-01-19 8:17 ` [PATCH 3/12] random pt3: Static sysctl bits Matt Mackall
2005-01-19 8:17 ` [PATCH 4/12] random pt3: Catastrophic reseed checks Matt Mackall
2005-01-19 8:17 ` [PATCH 5/12] random pt3: Entropy reservation accounting Matt Mackall
2005-01-19 8:17 ` [PATCH 6/12] random pt3: Reservation flag in pool struct Matt Mackall
2005-01-19 8:17 ` [PATCH 7/12] random pt3: Reseed pointer " Matt Mackall
2005-01-19 8:17 ` [PATCH 8/12] random pt3: Break up extract_user Matt Mackall
2005-01-19 8:17 ` [PATCH 9/12] random pt3: Remove dead MD5 copy Matt Mackall
2005-01-19 8:17 ` [PATCH 10/12] random pt3: Simplify hash folding Matt Mackall
2005-01-19 8:17 ` Matt Mackall [this message]
2005-01-19 8:17 ` [PATCH 12/12] random pt3: Remove entropy batching Matt Mackall
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