Make sure to seed the random number generator for uuids

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>

3 files changed, 22 insertions, 8 deletions

diff --git a/mdadm.c b/mdadm.c
index d8d46ee..c8b8e47 100644
--- a/mdadm.c
+++ b/mdadm.c
@@ -93,6 +93,8 @@ int main(int argc, char *argv[])
 
 	int mdfd = -1;
 
+	srandom(time(0) ^ getpid());
+
 	ident.uuid_set=0;
 	ident.level = UnSet;
 	ident.raid_disks = UnSet;
diff --git a/super0.c b/super0.c
index d6619d5..2b57147 100644
--- a/super0.c
+++ b/super0.c
@@ -326,6 +326,7 @@ static int init_super0(void **sbp, mdu_array_info_t *info)
 {
 	mdp_super_t *sb = malloc(MD_SB_BYTES);
 	int spares;
+	int rfd;
 	memset(sb, 0, MD_SB_BYTES);
 
 	if (info->major_version == -1) {
@@ -340,12 +341,14 @@ static int init_super0(void **sbp, mdu_array_info_t *info)
 		return 0;
 	}
 
+	rfd = open("/dev/urandom", O_RDONLY);
 	sb->md_magic = MD_SB_MAGIC;
 	sb->major_version = 0;
 	sb->minor_version = 90;
 	sb->patch_version = 0;
 	sb->gvalid_words = 0; /* ignored */
-	sb->set_uuid0 = random();
+	if (rfd < 0 || read(rfd, &sb->set_uuid0, 4) != 4)
+		sb->set_uuid0 = random();
 	sb->ctime = time(0);
 	sb->level = info->level;
 	sb->size = info->size;
@@ -353,9 +356,13 @@ static int init_super0(void **sbp, mdu_array_info_t *info)
 	sb->raid_disks = info->raid_disks;
 	sb->md_minor = info->md_minor;
 	sb->not_persistent = 0;
-	sb->set_uuid1 = random();
-	sb->set_uuid2 = random();
-	sb->set_uuid3 = random();
+	if (rfd < 0 || read(rfd, &sb->set_uuid1, 12) != 12) {
+		sb->set_uuid1 = random();
+		sb->set_uuid2 = random();
+		sb->set_uuid3 = random();
+	}
+	if (rfd >= 0)
+		close(rfd);
 
 	sb->utime = sb->ctime;
 	sb->state = info->state;
diff --git a/super1.c b/super1.c
index 751e28d..c5813b9 100644
--- a/super1.c
+++ b/super1.c
@@ -466,6 +466,7 @@ static int write_init_super1(struct supertype *st, void *sbv, mdu_disk_info_t *d
 	struct mdp_superblock_1 *sb = sbv;
 	struct mdp_superblock_1 *refsb = NULL;
 	int fd = open(devname, O_RDWR | O_EXCL);
+	int rfd;
 	int rv;
 
 	long size;
@@ -480,10 +481,14 @@ static int write_init_super1(struct supertype *st, void *sbv, mdu_disk_info_t *d
 
 	sb->dev_number = __cpu_to_le32(dinfo->number);
 
-	*(__u32*)(sb->device_uuid) = random();
-	*(__u32*)(sb->device_uuid+4) = random();
-	*(__u32*)(sb->device_uuid+8) = random();
-	*(__u32*)(sb->device_uuid+12) = random();
+	if ((rfd = open("/dev/urandom", O_RDONLY)) < 0 ||
+	    read(rfd, sb->device_uuid, 16) != 16) {
+		*(__u32*)(sb->device_uuid) = random();
+		*(__u32*)(sb->device_uuid+4) = random();
+		*(__u32*)(sb->device_uuid+8) = random();
+		*(__u32*)(sb->device_uuid+12) = random();
+	}
+	if (rfd >= 0) close(rfd);
 	sb->events = 0;
 
 	if (load_super1(st, fd, (void**)&refsb, NULL)==0) {