On Sun, Jul 16, 2023 at 11:52:36PM -0400, Sweet Tea Dorminy wrote:
> From: Omar Sandoval <osandov@xxxxxxxxxxx>
>
> In order to store encryption information for directories, symlinks,
> etc., fscrypt stores a context item with each encrypted non-regular
> inode. fscrypt provides an arbitrary blob for the filesystem to store,
> and it does not clearly fit into an existing structure, so this goes in
> a new item type.
>
> Signed-off-by: Omar Sandoval <osandov@xxxxxxxxxxx>
> Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@xxxxxxxxxx>
> ---
> fs/btrfs/fscrypt.c | 118 ++++++++++++++++++++++++++++++++
> fs/btrfs/fscrypt.h | 2 +
> fs/btrfs/inode.c | 19 +++++
> fs/btrfs/ioctl.c | 8 ++-
> include/uapi/linux/btrfs_tree.h | 10 +++
> 5 files changed, 155 insertions(+), 2 deletions(-)
>
> diff --git a/fs/btrfs/fscrypt.c b/fs/btrfs/fscrypt.c
> index 3a53dc59c1e4..1dfddf827cf8 100644
> --- a/fs/btrfs/fscrypt.c
> +++ b/fs/btrfs/fscrypt.c
> @@ -1,8 +1,126 @@
> // SPDX-License-Identifier: GPL-2.0
>
> +#include <linux/iversion.h>
> #include "ctree.h"
> +#include "accessors.h"
> +#include "btrfs_inode.h"
> +#include "disk-io.h"
> +#include "fs.h"
> #include "fscrypt.h"
> +#include "ioctl.h"
> +#include "messages.h"
> +#include "transaction.h"
> +#include "xattr.h"
> +
> +static int btrfs_fscrypt_get_context(struct inode *inode, void *ctx, size_t len)
> +{
> + struct btrfs_key key = {
> + .objectid = btrfs_ino(BTRFS_I(inode)),
> + .type = BTRFS_FSCRYPT_CTX_ITEM_KEY,
> + .offset = 0,
> + };
> + struct btrfs_path *path;
> + struct extent_buffer *leaf;
> + unsigned long ptr;
> + int ret;
> +
> +
> + path = btrfs_alloc_path();
> + if (!path)
> + return -ENOMEM;
> +
> + ret = btrfs_search_slot(NULL, BTRFS_I(inode)->root, &key, path, 0, 0);
> + if (ret) {
> + len = -ENOENT;
> + goto out;
> + }
> +
> + leaf = path->nodes[0];
> + ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
> + /* fscrypt provides max context length, but it could be less */
> + len = min_t(size_t, len, btrfs_item_size(leaf, path->slots[0]));
> + read_extent_buffer(leaf, ctx, ptr, len);
> +
> +out:
> + btrfs_free_path(path);
> + return len;
> +}
> +
> +static void btrfs_fscrypt_update_context(struct btrfs_path *path,
> + const void *ctx, size_t len)
> +{
> + struct extent_buffer *leaf = path->nodes[0];
> + unsigned long ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
> +
> + len = min_t(size_t, len, btrfs_item_size(leaf, path->slots[0]));
> + write_extent_buffer(leaf, ctx, ptr, len);
> + btrfs_mark_buffer_dirty(leaf);
> +}
> +
> +static int btrfs_fscrypt_set_context(struct inode *inode, const void *ctx,
> + size_t len, void *fs_data)
> +{
> + struct btrfs_path *path;
> + int ret;
> + struct btrfs_trans_handle *trans = fs_data;
> + struct btrfs_key key = {
> + .objectid = btrfs_ino(BTRFS_I(inode)),
> + .type = BTRFS_FSCRYPT_CTX_ITEM_KEY,
> + .offset = 0,
> + };
> + path = btrfs_alloc_path();
> + if (!path)
> + return -ENOMEM;
> +
Reorder the declarations above to make it cleaner, add a newline between the
variables and allocating path.
> + if (!trans)
> + trans = btrfs_start_transaction(BTRFS_I(inode)->root, 1);
> + if (IS_ERR(trans))
> + return PTR_ERR(trans);
> +
> + ret = btrfs_search_slot(trans, BTRFS_I(inode)->root, &key, path, 0, 1);
> + if (ret == 0) {
> + btrfs_fscrypt_update_context(path, ctx, len);
> + btrfs_free_path(path);
What do we do with the transaction if we started it above? Are we responsible
for stopping the transaction if it was provided via fsdata?
> + return ret;
> + }
> +
> + btrfs_free_path(path);
> + if (ret < 0) {
> + btrfs_abort_transaction(trans, ret);
> + return ret;
> + }
> +
> + ret = btrfs_insert_item(trans, BTRFS_I(inode)->root, &key, (void *) ctx, len);
We already have the path here, we can do
btrfs_release_path(path);
ret = btrfs_insert_empty_item(trans, BTRFS_I(inode)->root, &key, len);
if (ret) {
btrfs_abort_transaction(trans, ret);
btrfs_end_transaction(trans);
return ret;
}
ptr = btrfs_item_ptr_offset(path->nodes[0], path->slots[0]);
write_extent_buffer(path->nodes[0], ctx, ptr, len);
btrfs_mark_buffer_dirty(path->nodes[0]);
btrfs_free_path(path);
> + if (ret) {
> + btrfs_abort_transaction(trans, ret);
> + return ret;
> + }
> +
> + if (fs_data)
> + return ret;
> +
> + BTRFS_I(inode)->flags |= BTRFS_INODE_ENCRYPT;
> + btrfs_sync_inode_flags_to_i_flags(inode);
> + inode_inc_iversion(inode);
> + inode->i_ctime = current_time(inode);
> + ret = btrfs_update_inode(trans, BTRFS_I(inode)->root, BTRFS_I(inode));
> + if (!ret) {
> + btrfs_end_transaction(trans);
> + return ret;
> + }
> +
> + btrfs_abort_transaction(trans, ret);
Still need to call end_transaction if we abort if we started it. Thanks,
Josef
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