[PATCH v3 11/22] btrfs: start using fscrypt hooks

[Sweet Tea Dorminy <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. The
superblock must have fscrypt operations registered, so implement the
minimal set also, and introduce the new fscrypt.[ch] files to hold the
fscrypt-specific functionality.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
---
 fs/btrfs/Makefile  |  1 +
 fs/btrfs/ctree.h   |  1 +
 fs/btrfs/file.c    |  3 ++
 fs/btrfs/fscrypt.c |  7 ++++
 fs/btrfs/fscrypt.h | 10 +++++
 fs/btrfs/inode.c   | 91 ++++++++++++++++++++++++++++++++++++++++------
 fs/btrfs/super.c   |  2 +
 7 files changed, 103 insertions(+), 12 deletions(-)
 create mode 100644 fs/btrfs/fscrypt.c
 create mode 100644 fs/btrfs/fscrypt.h

diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile
index fa9ddcc9eb0b..55f9c2069e6e 100644
--- a/fs/btrfs/Makefile
+++ b/fs/btrfs/Makefile
@@ -38,6 +38,7 @@ btrfs-$(CONFIG_BTRFS_FS_CHECK_INTEGRITY) += check-integrity.o
 btrfs-$(CONFIG_BTRFS_FS_REF_VERIFY) += ref-verify.o
 btrfs-$(CONFIG_BLK_DEV_ZONED) += zoned.o
 btrfs-$(CONFIG_FS_VERITY) += verity.o
+btrfs-$(CONFIG_FS_ENCRYPTION) += fscrypt.o
 
 btrfs-$(CONFIG_BTRFS_FS_RUN_SANITY_TESTS) += tests/free-space-tests.o \
 	tests/extent-buffer-tests.o tests/btrfs-tests.o \
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 38aef923c33b..389c4e988318 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3067,6 +3067,7 @@ struct btrfs_new_inode_args {
 	struct posix_acl *default_acl;
 	struct posix_acl *acl;
 	struct fscrypt_name fname;
+	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 ca9c203d8cf1..87f428167efa 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -4009,6 +4009,9 @@ static int btrfs_file_open(struct inode *inode, struct file *filp)
 	int ret;
 
 	filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC | FMODE_BUF_WASYNC;
+	ret = fscrypt_file_open(inode, filp);
+	if (ret)
+		return ret;
 
 	ret = fsverity_file_open(inode, filp);
 	if (ret)
diff --git a/fs/btrfs/fscrypt.c b/fs/btrfs/fscrypt.c
new file mode 100644
index 000000000000..48ab99dfe48d
--- /dev/null
+++ b/fs/btrfs/fscrypt.c
@@ -0,0 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "ctree.h"
+#include "fscrypt.h"
+
+const struct fscrypt_operations btrfs_fscrypt_ops = {
+};
diff --git a/fs/btrfs/fscrypt.h b/fs/btrfs/fscrypt.h
new file mode 100644
index 000000000000..7f4e6888bd43
--- /dev/null
+++ b/fs/btrfs/fscrypt.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef BTRFS_FSCRYPT_H
+#define BTRFS_FSCRYPT_H
+
+#include <linux/fscrypt.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 63fd3521cdf9..2858ad470a02 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5447,6 +5447,7 @@ 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;
@@ -5548,6 +5549,7 @@ 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);
 }
@@ -6294,6 +6296,10 @@ 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 */
@@ -6770,9 +6776,13 @@ 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)
@@ -7053,6 +7063,7 @@ 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;
 
@@ -7060,9 +7071,13 @@ 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;
@@ -8880,6 +8895,7 @@ 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));
 }
 
@@ -8950,8 +8966,7 @@ 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)
@@ -9542,6 +9557,11 @@ 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);
@@ -9761,15 +9781,22 @@ 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 NUL terminator, but we
+	 * don't store that '\0' character.
+	 */
+	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)
@@ -9778,7 +9805,7 @@ 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;
@@ -9806,10 +9833,23 @@ 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) {
@@ -9828,10 +9868,11 @@ 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);
 
@@ -9848,6 +9889,29 @@ 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,
@@ -11419,7 +11483,7 @@ 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,
@@ -11429,4 +11493,7 @@ 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
 };
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 266712d22bc8..20123d3634a6 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -47,6 +47,7 @@
 #include "tests/btrfs-tests.h"
 #include "block-group.h"
 #include "discard.h"
+#include "fscrypt.h"
 #include "qgroup.h"
 #include "raid56.h"
 #define CREATE_TRACE_POINTS
@@ -1446,6 +1447,7 @@ static int btrfs_fill_super(struct super_block *sb,
 	sb->s_vop = &btrfs_verityops;
 #endif
 	sb->s_xattr = btrfs_xattr_handlers;
+	fscrypt_set_ops(sb, &btrfs_fscrypt_ops);
 	sb->s_time_gran = 1;
 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 	sb->s_flags |= SB_POSIXACL;
-- 
2.35.1