2014-01-30 Gerhard Heift <gerhard@xxxxxxxxxx>:
> By copying each found item seperatly to userspace, we do not need extra
> memory in the kernel. This allows to run a large search inside of a single call.
>
> Signed-off-by: Gerhard Heift <Gerhard@xxxxxxxxxx>
> ---
> fs/btrfs/ioctl.c | 52 ++++++++++++++++++++++++++++++++++++----------------
> 1 file changed, 36 insertions(+), 16 deletions(-)
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 10b9931..6daf23b 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -1855,7 +1855,7 @@ static noinline int copy_to_sk(struct btrfs_root *root,
> struct btrfs_key *key,
> struct btrfs_ioctl_search_key *sk,
> size_t *buf_size,
> - char *buf,
> + char __user *buf,
> unsigned long *sk_offset,
> int *num_found)
> {
> @@ -1890,7 +1890,7 @@ static noinline int copy_to_sk(struct btrfs_root *root,
> if (sizeof(sh) + item_len > *buf_size) {
> if (*num_found) {
> ret = 1;
> - goto overflow;
> + goto err;
> }
>
> /*
> @@ -1905,7 +1905,7 @@ static noinline int copy_to_sk(struct btrfs_root *root,
>
> if (sizeof(sh) + item_len + *sk_offset > *buf_size) {
> ret = 1;
> - goto overflow;
> + goto err;
> }
>
> sh.objectid = key->objectid;
> @@ -1915,20 +1915,28 @@ static noinline int copy_to_sk(struct btrfs_root *root,
> sh.transid = found_transid;
>
> /* copy search result header */
> - memcpy(buf + *sk_offset, &sh, sizeof(sh));
> + if (copy_to_user(buf + *sk_offset, &sh, sizeof(sh))) {
> + ret = -EFAULT;
> + goto err;
> + }
> +
> *sk_offset += sizeof(sh);
>
> if (item_len) {
> - char *p = buf + *sk_offset;
> + char __user *p = buf + *sk_offset;
> /* copy the item */
> - read_extent_buffer(leaf, p,
> - item_off, item_len);
> + if (read_extent_buffer_to_user(leaf, p,
> + item_off, item_len)) {
> + ret = -EFAULT;
> + goto err;
> + }
> +
> *sk_offset += item_len;
> }
> (*num_found)++;
>
> if (ret) /* -EOVERFLOW from above */
> - goto overflow;
> + goto err;
>
> if (*num_found >= sk->nr_items)
> break;
> @@ -1946,14 +1954,24 @@ advance_key:
> key->objectid++;
> } else
> ret = 1;
> -overflow:
> +err:
> + /*
> + * 0: all items from this leaf copied, continue with next
> + * 1: * more items can be copied, but unused buffer is too small
> + * * all items were found
> + * Either way, it will stops the loop which iterates to the next
> + * leaf
> + * -EOVERFLOW: item was to large for buffer
> + * -EFAULT: could not copy extent buffer back to userspace
> + */
> +
> return ret;
> }
>
> static noinline int search_ioctl(struct inode *inode,
> struct btrfs_ioctl_search_key *sk,
> size_t *buf_size,
> - char *buf)
> + char __user *buf)
> {
> struct btrfs_root *root;
> struct btrfs_key key;
> @@ -2004,6 +2022,7 @@ static noinline int search_ioctl(struct inode *inode,
> ret = copy_to_sk(root, path, &key, sk, buf_size, buf,
> &sk_offset, &num_found);
> btrfs_release_path(path);
> +
> if (ret || num_found >= sk->nr_items)
> break;
>
> @@ -2019,7 +2038,8 @@ err:
> static noinline int btrfs_ioctl_tree_search(struct file *file,
> void __user *argp)
> {
> - struct btrfs_ioctl_search_args *args;
> + struct btrfs_ioctl_search_args __user *args;
> + struct btrfs_ioctl_search_key sk;
> struct inode *inode;
> int ret;
> size_t buf_size;
> @@ -2027,14 +2047,15 @@ static noinline int btrfs_ioctl_tree_search(struct file *file,
> if (!capable(CAP_SYS_ADMIN))
> return -EPERM;
>
> - args = memdup_user(argp, sizeof(*args));
> - if (IS_ERR(args))
> - return PTR_ERR(args);
> + args = (struct btrfs_ioctl_search_args __user *)argp;
> +
> + if (copy_from_user(&sk, &args->key, sizeof(sk)))
> + return -EFAULT;
>
> buf_size = sizeof(args->buf);
>
> inode = file_inode(file);
> - ret = search_ioctl(inode, &args->key, &buf_size, args->buf);
> + ret = search_ioctl(inode, &sk, &buf_size, args->buf);
>
> /*
> * In the origin implementation an overflow is handled by returning a
> @@ -2045,7 +2066,6 @@ static noinline int btrfs_ioctl_tree_search(struct file *file,
>
> if (ret == 0 && copy_to_user(argp, args, sizeof(*args)))
Here I forgot to replace the full copy with only copying the search
key. The correct copy looks like this:
copy_to_user(&args->key, &sk, sizeof(sk))
I will post another version.
> ret = -EFAULT;
> - kfree(args);
> return ret;
> }
>
> --
> 1.8.5.3
>
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