random: fix seeding with zero entropy
Add data from zero-entropy random_writes directly to output pools to
avoid accounting difficulties on machines without entropy sources.
Tested on lguest with all entropy sources disabled.
Signed-off-by: Matt Mackall <mpm@selenic.com>
Acked-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 9705b43..0474cac 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1020,37 +1020,44 @@
return mask;
}
+static int
+write_pool(struct entropy_store *r, const char __user *buffer, size_t count)
+{
+ size_t bytes;
+ __u32 buf[16];
+ const char __user *p = buffer;
+
+ while (count > 0) {
+ bytes = min(count, sizeof(buf));
+ if (copy_from_user(&buf, p, bytes))
+ return -EFAULT;
+
+ count -= bytes;
+ p += bytes;
+
+ add_entropy_words(r, buf, (bytes + 3) / 4);
+ }
+
+ return 0;
+}
+
static ssize_t
random_write(struct file * file, const char __user * buffer,
size_t count, loff_t *ppos)
{
- int ret = 0;
- size_t bytes;
- __u32 buf[16];
- const char __user *p = buffer;
- size_t c = count;
+ size_t ret;
+ struct inode *inode = file->f_path.dentry->d_inode;
- while (c > 0) {
- bytes = min(c, sizeof(buf));
+ ret = write_pool(&blocking_pool, buffer, count);
+ if (ret)
+ return ret;
+ ret = write_pool(&nonblocking_pool, buffer, count);
+ if (ret)
+ return ret;
- bytes -= copy_from_user(&buf, p, bytes);
- if (!bytes) {
- ret = -EFAULT;
- break;
- }
- c -= bytes;
- p += bytes;
-
- add_entropy_words(&input_pool, buf, (bytes + 3) / 4);
- }
- if (p == buffer) {
- return (ssize_t)ret;
- } else {
- struct inode *inode = file->f_path.dentry->d_inode;
- inode->i_mtime = current_fs_time(inode->i_sb);
- mark_inode_dirty(inode);
- return (ssize_t)(p - buffer);
- }
+ inode->i_mtime = current_fs_time(inode->i_sb);
+ mark_inode_dirty(inode);
+ return (ssize_t)count;
}
static int
@@ -1089,8 +1096,8 @@
return -EINVAL;
if (get_user(size, p++))
return -EFAULT;
- retval = random_write(file, (const char __user *) p,
- size, &file->f_pos);
+ retval = write_pool(&input_pool, (const char __user *)p,
+ size);
if (retval < 0)
return retval;
credit_entropy_store(&input_pool, ent_count);