[PATCH 12/21] btrfs: start using fscrypt hooks.

From: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
To: Chris Mason <clm@fb.com>, Josef Bacik <josef@toxicpanda.com>,
	David Sterba <dsterba@suse.com>,
	"Theodore Y . Ts'o " <tytso@mit.edu>,
	Jaegeuk Kim <jaegeuk@kernel.org>,
	Eric Biggers <ebiggers@kernel.org>,
	linux-fscrypt@vger.kernel.org, linux-btrfs@vger.kernel.org,
	kernel-team@fb.com
Cc: Omar Sandoval <osandov@osandov.com>,
	Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Subject: [PATCH 12/21] btrfs: start using fscrypt hooks.
Date: Wed, 17 Aug 2022 10:49:56 -0400	[thread overview]
Message-ID: <becc7bf13f3afd9eb520b28bee45792f94111959.1660744500.git.sweettea-kernel@dorminy.me> (raw)
In-Reply-To: <cover.1660744500.git.sweettea-kernel@dorminy.me>

From: Omar Sandoval <osandov@osandov.com>

In order to appropriately encrypt, create, open, rename, and various symlink
operations must call fscrypt hooks. These determine whether the inode
should be encrypted and do other preparatory actions.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
---
 fs/btrfs/ctree.h |  1 +
 fs/btrfs/file.c  |  3 ++
 fs/btrfs/inode.c | 91 +++++++++++++++++++++++++++++++++++++++++-------
 3 files changed, 83 insertions(+), 12 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 96b72b90a1d0..a7e09b90d326 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3436,6 +3436,7 @@ struct btrfs_new_inode_args {
 	 */
 	struct posix_acl *default_acl;
 	struct posix_acl *acl;
+	bool encrypt;
 };
 int btrfs_new_inode_prepare(struct btrfs_new_inode_args *args,
 			    unsigned int *trans_num_items);
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index b2ffacef9abb..7b0f64ace064 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3709,6 +3709,9 @@ static int btrfs_file_open(struct inode *inode, struct file *filp)
 	int ret;
 
 	filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC;
+	ret = fscrypt_file_open(inode, filp);
+	if (ret)
+		return ret;
 
 	ret = fsverity_file_open(inode, filp);
 	if (ret)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 15104263059a..0fdd162d30bc 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5454,6 +5454,7 @@ void btrfs_evict_inode(struct inode *inode)
 	trace_btrfs_inode_evict(inode);
 
 	if (!root) {
+		fscrypt_put_encryption_info(inode);
 		fsverity_cleanup_inode(inode);
 		clear_inode(inode);
 		return;
@@ -5555,6 +5556,7 @@ void btrfs_evict_inode(struct inode *inode)
 	 * to retry these periodically in the future.
 	 */
 	btrfs_remove_delayed_node(BTRFS_I(inode));
+	fscrypt_put_encryption_info(inode);
 	fsverity_cleanup_inode(inode);
 	clear_inode(inode);
 }
@@ -6293,6 +6295,10 @@ int btrfs_new_inode_prepare(struct btrfs_new_inode_args *args,
 		return ret;
 	}
 
+	ret = fscrypt_prepare_new_inode(dir, inode, &args->encrypt);
+	if (ret)
+		return ret;
+
 	/* 1 to add inode item */
 	*trans_num_items = 1;
 	/* 1 to add compression property */
@@ -6771,9 +6777,13 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
 	if (inode->i_nlink >= BTRFS_LINK_MAX)
 		return -EMLINK;
 
+	err = fscrypt_prepare_link(old_dentry, dir, dentry);
+	if (err)
+		return err;
+
 	err = fscrypt_setup_filename(dir, &dentry->d_name, 0, &fname);
 	if (err)
-		goto fail;
+		return err;
 
 	err = btrfs_set_inode_index(BTRFS_I(dir), &index);
 	if (err)
@@ -7055,6 +7065,7 @@ struct extent_map *btrfs_get_extent(struct btrfs_inode *inode,
 		unsigned long ptr;
 		char *map;
 		size_t size;
+		size_t inline_size;
 		size_t extent_offset;
 		size_t copy_size;
 
@@ -7062,9 +7073,13 @@ struct extent_map *btrfs_get_extent(struct btrfs_inode *inode,
 			goto out;
 
 		size = btrfs_file_extent_ram_bytes(leaf, item);
+		inline_size = btrfs_file_extent_inline_item_len(leaf, path->slots[0]);
+		ASSERT(btrfs_file_extent_encryption(leaf, item) ||
+		       btrfs_file_extent_compression(leaf, item) ||
+		       (size == inline_size));
 		extent_offset = page_offset(page) + pg_offset - extent_start;
 		copy_size = min_t(u64, PAGE_SIZE - pg_offset,
-				  size - extent_offset);
+				  inline_size - extent_offset);
 		em->start = extent_start + extent_offset;
 		em->len = ALIGN(copy_size, fs_info->sectorsize);
 		em->orig_block_len = em->len;
@@ -9003,6 +9018,7 @@ void btrfs_test_destroy_inode(struct inode *inode)
 
 void btrfs_free_inode(struct inode *inode)
 {
+	fscrypt_free_inode(inode);
 	kmem_cache_free(btrfs_inode_cachep, BTRFS_I(inode));
 }
 
@@ -9073,8 +9089,7 @@ int btrfs_drop_inode(struct inode *inode)
 	/* the snap/subvol tree is on deleting */
 	if (btrfs_root_refs(&root->root_item) == 0)
 		return 1;
-	else
-		return generic_drop_inode(inode);
+	return generic_drop_inode(inode) || fscrypt_drop_inode(inode);
 }
 
 static void init_once(void *foo)
@@ -9688,6 +9703,11 @@ static int btrfs_rename2(struct user_namespace *mnt_userns, struct inode *old_di
 	if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
 		return -EINVAL;
 
+	ret = fscrypt_prepare_rename(old_dir, old_dentry, new_dir, new_dentry,
+				     flags);
+	if (ret)
+		return ret;
+
 	if (flags & RENAME_EXCHANGE)
 		ret = btrfs_rename_exchange(old_dir, old_dentry, new_dir,
 					    new_dentry);
@@ -9907,15 +9927,22 @@ static int btrfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
 	};
 	unsigned int trans_num_items;
 	int err;
-	int name_len;
 	int datasize;
 	unsigned long ptr;
 	struct btrfs_file_extent_item *ei;
 	struct extent_buffer *leaf;
+	struct fscrypt_str disk_link;
+	u32 name_len = strlen(symname);
 
-	name_len = strlen(symname);
-	if (name_len > BTRFS_MAX_INLINE_DATA_SIZE(fs_info))
-		return -ENAMETOOLONG;
+	/*
+	 * fscrypt sets disk_link.len to be len + 1, including a NULL terminator, but we
+	 * don't store that NULL.
+	 */
+	err = fscrypt_prepare_symlink(dir, symname, name_len,
+				      BTRFS_MAX_INLINE_DATA_SIZE(fs_info) + 1,
+				      &disk_link);
+	if (err)
+		return err;
 
 	inode = new_inode(dir->i_sb);
 	if (!inode)
@@ -9924,7 +9951,7 @@ static int btrfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
 	inode->i_op = &btrfs_symlink_inode_operations;
 	inode_nohighmem(inode);
 	inode->i_mapping->a_ops = &btrfs_aops;
-	btrfs_i_size_write(BTRFS_I(inode), name_len);
+	btrfs_i_size_write(BTRFS_I(inode), disk_link.len - 1);
 	inode_set_bytes(inode, name_len);
 
 	new_inode_args.inode = inode;
@@ -9952,10 +9979,23 @@ static int btrfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
 		inode = NULL;
 		goto out;
 	}
+
+	if (IS_ENCRYPTED(inode)) {
+		err = fscrypt_encrypt_symlink(inode, symname, name_len,
+					      &disk_link);
+		if (err) {
+			btrfs_abort_transaction(trans, err);
+			btrfs_free_path(path);
+			discard_new_inode(inode);
+			inode = NULL;
+			goto out;
+		}
+	}
+
 	key.objectid = btrfs_ino(BTRFS_I(inode));
 	key.offset = 0;
 	key.type = BTRFS_EXTENT_DATA_KEY;
-	datasize = btrfs_file_extent_calc_inline_size(name_len);
+	datasize = btrfs_file_extent_calc_inline_size(disk_link.len - 1);
 	err = btrfs_insert_empty_item(trans, root, path, &key,
 				      datasize);
 	if (err) {
@@ -9974,10 +10014,11 @@ static int btrfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
 	btrfs_set_file_extent_encryption(leaf, ei, 0);
 	btrfs_set_file_extent_compression(leaf, ei, 0);
 	btrfs_set_file_extent_other_encoding(leaf, ei, 0);
+	/* ram size is the unencoded size */
 	btrfs_set_file_extent_ram_bytes(leaf, ei, name_len);
 
 	ptr = btrfs_file_extent_inline_start(ei);
-	write_extent_buffer(leaf, symname, ptr, name_len);
+	write_extent_buffer(leaf, disk_link.name, ptr, disk_link.len - 1);
 	btrfs_mark_buffer_dirty(leaf);
 	btrfs_free_path(path);
 
@@ -9994,6 +10035,29 @@ static int btrfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
 	return err;
 }
 
+static const char *btrfs_get_link(struct dentry *dentry, struct inode *inode,
+				  struct delayed_call *done)
+{
+	struct page *cpage;
+	const char *paddr;
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+
+	if (!IS_ENCRYPTED(inode))
+		return page_get_link(dentry, inode, done);
+
+	if (!dentry)
+		return ERR_PTR(-ECHILD);
+
+	cpage = read_mapping_page(inode->i_mapping, 0, NULL);
+	if (IS_ERR(cpage))
+		return ERR_CAST(cpage);
+
+	paddr = fscrypt_get_symlink(inode, page_address(cpage),
+				    BTRFS_MAX_INLINE_DATA_SIZE(fs_info), done);
+	put_page(cpage);
+	return paddr;
+}
+
 static struct btrfs_trans_handle *insert_prealloc_file_extent(
 				       struct btrfs_trans_handle *trans_in,
 				       struct btrfs_inode *inode,
@@ -11580,7 +11644,7 @@ static const struct inode_operations btrfs_special_inode_operations = {
 	.update_time	= btrfs_update_time,
 };
 static const struct inode_operations btrfs_symlink_inode_operations = {
-	.get_link	= page_get_link,
+	.get_link	= btrfs_get_link,
 	.getattr	= btrfs_getattr,
 	.setattr	= btrfs_setattr,
 	.permission	= btrfs_permission,
@@ -11590,4 +11654,7 @@ static const struct inode_operations btrfs_symlink_inode_operations = {
 
 const struct dentry_operations btrfs_dentry_operations = {
 	.d_delete	= btrfs_dentry_delete,
+#ifdef CONFIG_FS_ENCRYPTION
+	.d_revalidate	= fscrypt_d_revalidate,
+#endif
 };
-- 
2.35.1

