| Message ID | adfd6682729107364481959f2ee4850c276ce211.1691510179.git.sweettea-kernel@dorminy.me (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | btrfs: add encryption feature | expand |
On Tue, Aug 08, 2023 at 01:12:10PM -0400, Sweet Tea Dorminy wrote: > For encrypted or unencrypted names, we calculate the offset for the dir > item by hashing the name for the dir item. However, this doesn't work > for a long nokey name, where we do not have the complete ciphertext. > Instead, fscrypt stores the filesystem-provided hash in the nokey name, > and we can extract it from the fscrypt_name structure in such a case. > > Additionally, for nokey names, if we find the nokey name on disk we can > update the fscrypt_name with the disk name, so add that to searching for > diritems. > > Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me> > --- > fs/btrfs/dir-item.c | 37 +++++++++++++++++++++++++++++++++++-- > fs/btrfs/fscrypt.c | 27 +++++++++++++++++++++++++++ > fs/btrfs/fscrypt.h | 11 +++++++++++ > 3 files changed, 73 insertions(+), 2 deletions(-) > > diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c > index da95ae411d72..ee7dad888f53 100644 > --- a/fs/btrfs/dir-item.c > +++ b/fs/btrfs/dir-item.c > @@ -231,6 +231,28 @@ struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans, > return di; > } > > +/* > + * If appropriate, populate the disk name for a fscrypt_name looked up without > + * a key. > + * > + * @path: The path to the extent buffer in which the name was found. > + * @di: The dir item corresponding. > + * @fname: The fscrypt_name to perhaps populate. > + * > + * Returns: 0 if the name is already populated or the dir item doesn't exist > + * or the name was successfully populated, else an error code. > + */ > +static int ensure_disk_name_from_dir_item(struct btrfs_path *path, > + struct btrfs_dir_item *di, > + struct fscrypt_name *name) > +{ > + if (name->disk_name.name || !di) > + return 0; > + > + return btrfs_fscrypt_get_disk_name(path->nodes[0], di, > + &name->disk_name); > +} > + > /* > * Lookup for a directory item by fscrypt_name. > * > @@ -257,8 +279,12 @@ struct btrfs_dir_item *btrfs_lookup_dir_item_fname(struct btrfs_trans_handle *tr > > key.objectid = dir; > key.type = BTRFS_DIR_ITEM_KEY; > - key.offset = btrfs_name_hash(name->disk_name.name, name->disk_name.len); > - /* XXX get the right hash for no-key names */ > + > + if (!name->disk_name.name) > + key.offset = name->hash | ((u64)name->minor_hash << 32); > + else > + key.offset = btrfs_name_hash(name->disk_name.name, > + name->disk_name.len); > > ret = btrfs_search_slot(trans, root, &key, path, mod, -mod); > if (ret == 0) > @@ -266,6 +292,8 @@ struct btrfs_dir_item *btrfs_lookup_dir_item_fname(struct btrfs_trans_handle *tr > > if (ret == -ENOENT || (di && IS_ERR(di) && PTR_ERR(di) == -ENOENT)) > return NULL; > + if (ret == 0) > + ret = ensure_disk_name_from_dir_item(path, di, name); > if (ret < 0) > di = ERR_PTR(ret); > > @@ -382,7 +410,12 @@ btrfs_search_dir_index_item(struct btrfs_root *root, struct btrfs_path *path, > btrfs_for_each_slot(root, &key, &key, path, ret) { > if (key.objectid != dirid || key.type != BTRFS_DIR_INDEX_KEY) > break; > + > di = btrfs_match_dir_item_fname(root->fs_info, path, name); > + if (di) > + ret = ensure_disk_name_from_dir_item(path, di, name); > + if (ret) > + break; This is a little wonky, I'd rather just if (!di) continue; ret = ensure_disk_name_from_dir_item(path, di, name); if (ret) break return di; Thanks, Josef
diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c index da95ae411d72..ee7dad888f53 100644 --- a/fs/btrfs/dir-item.c +++ b/fs/btrfs/dir-item.c @@ -231,6 +231,28 @@ struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans, return di; } +/* + * If appropriate, populate the disk name for a fscrypt_name looked up without + * a key. + * + * @path: The path to the extent buffer in which the name was found. + * @di: The dir item corresponding. + * @fname: The fscrypt_name to perhaps populate. + * + * Returns: 0 if the name is already populated or the dir item doesn't exist + * or the name was successfully populated, else an error code. + */ +static int ensure_disk_name_from_dir_item(struct btrfs_path *path, + struct btrfs_dir_item *di, + struct fscrypt_name *name) +{ + if (name->disk_name.name || !di) + return 0; + + return btrfs_fscrypt_get_disk_name(path->nodes[0], di, + &name->disk_name); +} + /* * Lookup for a directory item by fscrypt_name. * @@ -257,8 +279,12 @@ struct btrfs_dir_item *btrfs_lookup_dir_item_fname(struct btrfs_trans_handle *tr key.objectid = dir; key.type = BTRFS_DIR_ITEM_KEY; - key.offset = btrfs_name_hash(name->disk_name.name, name->disk_name.len); - /* XXX get the right hash for no-key names */ + + if (!name->disk_name.name) + key.offset = name->hash | ((u64)name->minor_hash << 32); + else + key.offset = btrfs_name_hash(name->disk_name.name, + name->disk_name.len); ret = btrfs_search_slot(trans, root, &key, path, mod, -mod); if (ret == 0) @@ -266,6 +292,8 @@ struct btrfs_dir_item *btrfs_lookup_dir_item_fname(struct btrfs_trans_handle *tr if (ret == -ENOENT || (di && IS_ERR(di) && PTR_ERR(di) == -ENOENT)) return NULL; + if (ret == 0) + ret = ensure_disk_name_from_dir_item(path, di, name); if (ret < 0) di = ERR_PTR(ret); @@ -382,7 +410,12 @@ btrfs_search_dir_index_item(struct btrfs_root *root, struct btrfs_path *path, btrfs_for_each_slot(root, &key, &key, path, ret) { if (key.objectid != dirid || key.type != BTRFS_DIR_INDEX_KEY) break; + di = btrfs_match_dir_item_fname(root->fs_info, path, name); + if (di) + ret = ensure_disk_name_from_dir_item(path, di, name); + if (ret) + break; if (di) return di; } diff --git a/fs/btrfs/fscrypt.c b/fs/btrfs/fscrypt.c index fcd926907f82..bdd58415f93c 100644 --- a/fs/btrfs/fscrypt.c +++ b/fs/btrfs/fscrypt.c @@ -14,6 +14,33 @@ #include "transaction.h" #include "xattr.h" +/* + * From a given location in a leaf, read a name into a qstr (usually a + * fscrypt_name's disk_name), allocating the required buffer. Used for + * nokey names. + */ +int btrfs_fscrypt_get_disk_name(struct extent_buffer *leaf, + struct btrfs_dir_item *dir_item, + struct fscrypt_str *name) +{ + unsigned long de_name_len = btrfs_dir_name_len(leaf, dir_item); + unsigned long de_name = (unsigned long)(dir_item + 1); + /* + * For no-key names, we use this opportunity to find the disk + * name, so future searches don't need to deal with nokey names + * and we know what the encrypted size is. + */ + name->name = kmalloc(de_name_len, GFP_NOFS); + + if (!name->name) + return -ENOMEM; + + read_extent_buffer(leaf, name->name, de_name, de_name_len); + + name->len = de_name_len; + return 0; +} + /* * This function is extremely similar to fscrypt_match_name() but uses an * extent_buffer. diff --git a/fs/btrfs/fscrypt.h b/fs/btrfs/fscrypt.h index 1647bbbcd609..c08fd52c99b4 100644 --- a/fs/btrfs/fscrypt.h +++ b/fs/btrfs/fscrypt.h @@ -9,11 +9,22 @@ #include "fs.h" #ifdef CONFIG_FS_ENCRYPTION +int btrfs_fscrypt_get_disk_name(struct extent_buffer *leaf, + struct btrfs_dir_item *di, + struct fscrypt_str *qstr); + bool btrfs_fscrypt_match_name(struct fscrypt_name *fname, struct extent_buffer *leaf, unsigned long de_name, u32 de_name_len); #else +static inline int btrfs_fscrypt_get_disk_name(struct extent_buffer *leaf, + struct btrfs_dir_item *di, + struct fscrypt_str *qstr) +{ + return 0; +} + static inline bool btrfs_fscrypt_match_name(struct fscrypt_name *fname, struct extent_buffer *leaf, unsigned long de_name,
For encrypted or unencrypted names, we calculate the offset for the dir item by hashing the name for the dir item. However, this doesn't work for a long nokey name, where we do not have the complete ciphertext. Instead, fscrypt stores the filesystem-provided hash in the nokey name, and we can extract it from the fscrypt_name structure in such a case. Additionally, for nokey names, if we find the nokey name on disk we can update the fscrypt_name with the disk name, so add that to searching for diritems. Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me> --- fs/btrfs/dir-item.c | 37 +++++++++++++++++++++++++++++++++++-- fs/btrfs/fscrypt.c | 27 +++++++++++++++++++++++++++ fs/btrfs/fscrypt.h | 11 +++++++++++ 3 files changed, 73 insertions(+), 2 deletions(-)