[PATCH v4 12/46] btrfs: add inode encryption contexts

Josef Bacik
2023-12-01T22:12:12Z

From: Omar Sandoval <osandov@osandov.com>

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@osandov.com>
Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
fs/btrfs/fscrypt.c | 117 ++++++++++++++++++++++++++++++++
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, 154 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/fscrypt.c b/fs/btrfs/fscrypt.c
index 48ab99dfe48d..0e4011d6b1cd 100644
--- a/fs/btrfs/fscrypt.c
+++ b/fs/btrfs/fscrypt.c
@@ -1,7 +1,124 @@
// 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 int btrfs_fscrypt_set_context(struct inode *inode, const void *ctx,
+ size_t len, void *fs_data)
+{
+ 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,
+ };
+ struct btrfs_path *path = NULL;
+ struct extent_buffer *leaf;
+ unsigned long ptr;
+ int ret;
+
+ if (!trans)
+ trans = btrfs_start_transaction(BTRFS_I(inode)->root, 2);
+ if (IS_ERR(trans))
+ return PTR_ERR(trans);
+
+ path = btrfs_alloc_path();
+ if (!path) {
+ ret = -ENOMEM;
+ goto out_err;
+ }
+
+ ret = btrfs_search_slot(trans, BTRFS_I(inode)->root, &key, path, 0, 1);
+ if (ret < 0)
+ goto out_err;
+
+ if (ret > 0) {
+ btrfs_release_path(path);
+ ret = btrfs_insert_empty_item(trans, BTRFS_I(inode)->root, path, &key, len);
+ if (ret)
+ goto out_err;
+ }
+
+ leaf = path->nodes[0];
+ 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(trans, leaf);
+ btrfs_release_path(path);
+
+ 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_set_ctime_current(inode);
+ ret = btrfs_update_inode(trans, BTRFS_I(inode));
+ if (ret)
+ goto out_abort;
+ btrfs_free_path(path);
+ btrfs_end_transaction(trans);
+ return 0;
+out_abort:
+ btrfs_abort_transaction(trans, ret);
+out_err:
+ if (!fs_data)
+ btrfs_end_transaction(trans);
+ btrfs_free_path(path);
+ return ret;
+}
+
+static bool btrfs_fscrypt_empty_dir(struct inode *inode)
+{
+ return inode->i_size == BTRFS_EMPTY_DIR_SIZE;
+}

const struct fscrypt_operations btrfs_fscrypt_ops = {
+ .get_context = btrfs_fscrypt_get_context,
+ .set_context = btrfs_fscrypt_set_context,
+ .empty_dir = btrfs_fscrypt_empty_dir,
};
diff --git a/fs/btrfs/fscrypt.h b/fs/btrfs/fscrypt.h
index 7f4e6888bd43..80adb7e56826 100644
--- a/fs/btrfs/fscrypt.h
+++ b/fs/btrfs/fscrypt.h
@@ -5,6 +5,8 @@

#include <linux/fscrypt.h>

+#include "fs.h"
+
extern const struct fscrypt_operations btrfs_fscrypt_ops;

#endif /* BTRFS_FSCRYPT_H */
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index d58003eb447d..cc52af10a520 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -62,6 +62,7 @@
#include "defrag.h"
#include "dir-item.h"
#include "file-item.h"
+#include "fscrypt.h"
#include "uuid-tree.h"
#include "ioctl.h"
#include "file.h"
@@ -6097,6 +6098,9 @@ int btrfs_new_inode_prepare(struct btrfs_new_inode_args *args,
struct inode *inode = args->inode;
int ret;

+ if (fscrypt_is_nokey_name(args->dentry))
+ return -ENOKEY;
+
if (!args->orphan) {
ret = fscrypt_setup_filename(dir, &args->dentry->d_name, 0,
&args->fname);
@@ -6132,6 +6136,9 @@ int btrfs_new_inode_prepare(struct btrfs_new_inode_args *args,
if (dir->i_security)
(*trans_num_items)++;
#endif
+ /* 1 to add fscrypt item */
+ if (args->encrypt)
+ (*trans_num_items)++;
if (args->orphan) {
/* 1 to add orphan item */
(*trans_num_items)++;
@@ -6317,6 +6324,11 @@ int btrfs_create_new_inode(struct btrfs_trans_handle *trans,
BTRFS_I(inode)->i_otime_sec = ts.tv_sec;
BTRFS_I(inode)->i_otime_nsec = ts.tv_nsec;

+ if (args->encrypt) {
+ BTRFS_I(inode)->flags |= BTRFS_INODE_ENCRYPT;
+ btrfs_sync_inode_flags_to_i_flags(inode);
+ }
+
/*
* We're going to fill the inode item now, so at this point the inode
* must be fully initialized.
@@ -6391,6 +6403,13 @@ int btrfs_create_new_inode(struct btrfs_trans_handle *trans,
goto discard;
}
}
+ if (args->encrypt) {
+ ret = fscrypt_set_context(inode, trans);
+ if (ret) {
+ btrfs_abort_transaction(trans, ret);
+ goto discard;
+ }
+ }

inode_tree_add(BTRFS_I(inode));

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index dfe257e1845b..6acf898f693e 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -156,6 +156,8 @@ static unsigned int btrfs_inode_flags_to_fsflags(struct btrfs_inode *binode)
iflags |= FS_DIRSYNC_FL;
if (flags & BTRFS_INODE_NODATACOW)
iflags |= FS_NOCOW_FL;
+ if (flags & BTRFS_INODE_ENCRYPT)
+ iflags |= FS_ENCRYPT_FL;
if (ro_flags & BTRFS_INODE_RO_VERITY)
iflags |= FS_VERITY_FL;

@@ -185,12 +187,14 @@ void btrfs_sync_inode_flags_to_i_flags(struct inode *inode)
new_fl |= S_NOATIME;
if (binode->flags & BTRFS_INODE_DIRSYNC)
new_fl |= S_DIRSYNC;
+ if (binode->flags & BTRFS_INODE_ENCRYPT)
+ new_fl |= S_ENCRYPTED;
if (binode->ro_flags & BTRFS_INODE_RO_VERITY)
new_fl |= S_VERITY;

set_mask_bits(&inode->i_flags,
S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME | S_DIRSYNC |
- S_VERITY, new_fl);
+ S_VERITY | S_ENCRYPTED, new_fl);
}

/*
@@ -203,7 +207,7 @@ static int check_fsflags(unsigned int old_flags, unsigned int flags)
FS_NOATIME_FL | FS_NODUMP_FL | \
FS_SYNC_FL | FS_DIRSYNC_FL | \
FS_NOCOMP_FL | FS_COMPR_FL |
- FS_NOCOW_FL))
+ FS_NOCOW_FL | FS_ENCRYPT_FL))
return -EOPNOTSUPP;

/* COMPR and NOCOMP on new/old are valid */
diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index d24e8e121507..08f561da33cd 100644
--- a/include/uapi/linux/btrfs_tree.h
+++ b/include/uapi/linux/btrfs_tree.h
@@ -164,6 +164,8 @@
#define BTRFS_VERITY_DESC_ITEM_KEY 36
#define BTRFS_VERITY_MERKLE_ITEM_KEY 37

+#define BTRFS_FSCRYPT_CTX_ITEM_KEY 41
+
#define BTRFS_ORPHAN_ITEM_KEY 48
/* reserve 2-15 close to the inode for later flexibility */

@@ -424,6 +426,7 @@ static inline __u8 btrfs_dir_flags_to_ftype(__u8 flags)
#define BTRFS_INODE_NOATIME (1U << 9)
#define BTRFS_INODE_DIRSYNC (1U << 10)
#define BTRFS_INODE_COMPRESS (1U << 11)
+#define BTRFS_INODE_ENCRYPT (1U << 12)

#define BTRFS_INODE_ROOT_ITEM_INIT (1U << 31)

@@ -440,6 +443,7 @@ static inline __u8 btrfs_dir_flags_to_ftype(__u8 flags)
BTRFS_INODE_NOATIME | \
BTRFS_INODE_DIRSYNC | \
BTRFS_INODE_COMPRESS | \
+ BTRFS_INODE_ENCRYPT | \
BTRFS_INODE_ROOT_ITEM_INIT)

#define BTRFS_INODE_RO_VERITY (1U << 0)
@@ -1069,6 +1073,12 @@ enum {
BTRFS_NR_FILE_EXTENT_TYPES = 3,
};

+enum {
+ BTRFS_ENCRYPTION_NONE,
+ BTRFS_ENCRYPTION_FSCRYPT,
+ BTRFS_NR_ENCRYPTION_TYPES,
+};
+
struct btrfs_file_extent_item {
/*
* transaction id that created this extent
--
2.41.0