From: Philip Homburg <philip@cs.vu.nl>
Date: Tue, 19 Jul 2005 12:16:55 +0000 (+0000)
Subject: Small update to random number generator
X-Git-Tag: v3.1.0~598
X-Git-Url: http://zhaoyanbai.com/repos/icons/apache_pb.png?a=commitdiff_plain;h=f8c380c195a46b048d03ec5d0192fc5451dcac87;p=minix.git

Small update to random number generator
---

diff --git a/drivers/memory/memory.c b/drivers/memory/memory.c
index 90cd512bd..6ffd44baa 100644
--- a/drivers/memory/memory.c
+++ b/drivers/memory/memory.c
@@ -27,7 +27,7 @@
 #include "random.h"
 
 #define NR_DEVS            7		/* number of minor devices */
-#define KRANDOM_PERIOD    10 		/* ticks between krandom calls */
+#define KRANDOM_PERIOD    1 		/* ticks between krandom calls */
 
 PRIVATE struct device m_geom[NR_DEVS];  /* base and size of each device */
 PRIVATE int m_seg[NR_DEVS];  		/* segment index of each device */
@@ -183,12 +183,8 @@ unsigned nr_req;		/* length of request vector */
 
 	/* Random number generator. Character instead of block device. */
 	case RANDOM_DEV:
-	    if (opcode == DEV_GATHER)
-	    {
-		s= random_reseed();
-		if (s < 0)
+	    if (opcode == DEV_GATHER && !random_isseeded())
 		    return(EAGAIN);
-	    }
 	    left = count;
 	    while (left > 0) {
 	    	chunk = (left > RANDOM_BUF_SIZE) ? RANDOM_BUF_SIZE : left;
diff --git a/drivers/memory/random.c b/drivers/memory/random.c
index f58236ea6..f49320480 100644
--- a/drivers/memory/random.c
+++ b/drivers/memory/random.c
@@ -33,6 +33,7 @@ PRIVATE u32_t reseed_count;
 FORWARD _PROTOTYPE( void add_sample, (int source, unsigned long sample)	);
 FORWARD _PROTOTYPE( void data_block, (rd_keyinstance *keyp,
 							void *data)	);
+FORWARD _PROTOTYPE( void reseed, (void)					);
 
 PUBLIC void random_init()
 {
@@ -54,42 +55,11 @@ PUBLIC void random_init()
 	reseed_count= 0;
 }
 
-PUBLIC int random_reseed()
+PUBLIC int random_isseeded()
 {
-	int i;
-	SHA256_CTX ctx;
-	u8_t digest[SHA256_DIGEST_LENGTH];
-
-	if (samples >= MIN_SAMPLES)
-	{
-		reseed_count++;
-		printf("random_reseed:  round %d, samples = %d\n",
-			reseed_count, samples);
-		SHA256_Init(&ctx);
-		if (got_seeded)
-			SHA256_Update(&ctx, random_key, sizeof(random_key));
-		SHA256_Final(digest, &pool_ctx[0]);
-		SHA256_Update(&ctx, digest, sizeof(digest));
-		SHA256_Init(&pool_ctx[0]);
-		for (i= 1; i<NR_POOLS; i++)
-		{
-			if ((reseed_count & (1UL << (i-1))) != 0)
-				break;
-			printf("random_reseed: adding pool %d\n", i);
-			SHA256_Final(digest, &pool_ctx[i]);
-			SHA256_Update(&ctx, digest, sizeof(digest));
-			SHA256_Init(&pool_ctx[i]);
-		}
-		SHA256_Final(digest, &ctx);
-		assert(sizeof(random_key) == sizeof(digest));
-		memcpy(random_key, &digest, sizeof(random_key));
-		samples= 0;
-
-		got_seeded= 1;
-	}
 	if (got_seeded)
-		return 0;
-	return -1;
+		return 1;
+	return 0;
 }
 
 PUBLIC void random_update(source, buf, count)
@@ -106,6 +76,7 @@ int count;
 		panic("memory", "random_update: bad source", source);
 	for (i= 0; i<count; i++)
 		add_sample(source, buf[i]);
+	reseed();
 }
 
 PUBLIC void random_getbytes(buf, size)
@@ -153,6 +124,8 @@ size_t size;
 	 * with the number of bits.
 	 */
 	samples += size*8;
+
+	reseed();
 }
 
 PRIVATE void add_sample(source, sample)
@@ -230,3 +203,38 @@ void *data;
 	if (count_lo == 0)
 		count_hi++;
 }
+
+PRIVATE void reseed()
+{
+	int i;
+	SHA256_CTX ctx;
+	u8_t digest[SHA256_DIGEST_LENGTH];
+
+	if (samples < MIN_SAMPLES)
+		return;
+
+	reseed_count++;
+	printf("reseed: round %d, samples = %d\n", reseed_count, samples);
+	SHA256_Init(&ctx);
+	if (got_seeded)
+		SHA256_Update(&ctx, random_key, sizeof(random_key));
+	SHA256_Final(digest, &pool_ctx[0]);
+	SHA256_Update(&ctx, digest, sizeof(digest));
+	SHA256_Init(&pool_ctx[0]);
+	for (i= 1; i<NR_POOLS; i++)
+	{
+		if ((reseed_count & (1UL << (i-1))) != 0)
+			break;
+		printf("random_reseed: adding pool %d\n", i);
+		SHA256_Final(digest, &pool_ctx[i]);
+		SHA256_Update(&ctx, digest, sizeof(digest));
+		SHA256_Init(&pool_ctx[i]);
+	}
+	SHA256_Final(digest, &ctx);
+	assert(sizeof(random_key) == sizeof(digest));
+	memcpy(random_key, &digest, sizeof(random_key));
+	samples= 0;
+
+	got_seeded= 1;
+}
+
diff --git a/drivers/memory/random.h b/drivers/memory/random.h
index d238f397c..ffd6b3694 100644
--- a/drivers/memory/random.h
+++ b/drivers/memory/random.h
@@ -5,7 +5,7 @@ Public interface to the random number generator
 */
 
 _PROTOTYPE( void random_init, (void)					);
-_PROTOTYPE( int random_reseed, (void)					);
+_PROTOTYPE( int random_isseeded, (void)					);
 _PROTOTYPE( void random_update, (int source, unsigned long *buf, 
 							int count)	);
 _PROTOTYPE( void random_getbytes, (void *buf, size_t size)		);
diff --git a/etc/usr/rc b/etc/usr/rc
index 7696ff48b..106bcd79f 100644
--- a/etc/usr/rc
+++ b/etc/usr/rc
@@ -26,6 +26,8 @@ daemonize()
     done
 }
 
+RANDOM_FILE=/usr/adm/random.dat
+
 case $action in
 start)
     # Select console font.
@@ -34,6 +36,14 @@ start)
     # Cleanup.
     rm -rf /tmp/. /usr/run/. /usr/spool/lpd/. /usr/spool/locks/.
 
+    # load random number generator
+    if [ -f $RANDOM_FILE ]
+    then
+    	cat < $RANDOM_FILE >/dev/random
+    	# overwrite $RANDOM_FILE. We don't want to use this data again
+    	dd if=/dev/random of=$RANDOM_FILE bs=1024 count=1
+    fi
+
     # Start servers.
     ifs="$IFS"; IFS=,
     for server in `sysenv servers`; do daemonize $server; done
@@ -106,4 +116,14 @@ prompt to investigate, otherwise just wait until an address is received..."
 
     # Run the daily cleanup on systems that are not on at night.
     test -f /usr/etc/daily && sh /usr/etc/daily boot &
+
+;;
+stop|down)
+    	# Save random data.
+    	if dd if=/dev/random of=$RANDOM_FILE.new bs=1024 count=1 2>/dev/null
+    	then
+    		mv $RANDOM_FILE.new $RANDOM_FILE
+	else
+		echo 'Failed to save random data.'
+	fi
 esac