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authorMatt Mackall <mpm@selenic.com>2007-05-29 21:58:10 -0500
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-29 20:09:34 -0700
commit7f397dcdb78d699a20d96bfcfb595a2411a5bbd2 (patch)
tree7ecb0b2f782a4e18eef80ff638f0469cd4ad0233 /drivers
parent602b6aeefe8932dd8bb15014e8fe6bb25d736361 (diff)
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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/char/random.c55
1 files changed, 31 insertions, 24 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 9705b439448..0474cac4a84 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1020,37 +1020,44 @@ random_poll(struct file *file, poll_table * wait)
return mask;
}
-static ssize_t
-random_write(struct file * file, const char __user * buffer,
- size_t count, loff_t *ppos)
+static int
+write_pool(struct entropy_store *r, const char __user *buffer, size_t count)
{
- int ret = 0;
size_t bytes;
__u32 buf[16];
const char __user *p = buffer;
- size_t c = count;
- while (c > 0) {
- bytes = min(c, sizeof(buf));
+ while (count > 0) {
+ bytes = min(count, sizeof(buf));
+ if (copy_from_user(&buf, p, bytes))
+ return -EFAULT;
- bytes -= copy_from_user(&buf, p, bytes);
- if (!bytes) {
- ret = -EFAULT;
- break;
- }
- c -= bytes;
+ count -= 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);
+ 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)
+{
+ size_t ret;
+ struct inode *inode = file->f_path.dentry->d_inode;
+
+ ret = write_pool(&blocking_pool, buffer, count);
+ if (ret)
+ return ret;
+ ret = write_pool(&nonblocking_pool, buffer, count);
+ if (ret)
+ return ret;
+
+ inode->i_mtime = current_fs_time(inode->i_sb);
+ mark_inode_dirty(inode);
+ return (ssize_t)count;
}
static int
@@ -1089,8 +1096,8 @@ random_ioctl(struct inode * inode, struct file * file,
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);