[PATCH v7 10/43] btrfs: start using fscrypt hooks

[Daniel Vacek <neelx@suse.com>]

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>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Daniel Vacek <neelx@suse.com>
---

v7 changes:
 * Fix rebase conflicts.
 * Fix a memory leak as suggested by Chris' AI review.
v6 changes:
 * FSCrypt info moved from VFS inode to FS specific inode structure.
 * Trivial renames.
v5: https://lore.kernel.org/linux-btrfs/333de15efb2d7ec220293c4b5e3782fe85634c06.1706116485.git.josef@toxicpanda.com/
---
 fs/btrfs/Makefile      |   1 +
 fs/btrfs/btrfs_inode.h |   5 ++
 fs/btrfs/file.c        |   3 ++
 fs/btrfs/fscrypt.c     |  10 ++++
 fs/btrfs/fscrypt.h     |  10 ++++
 fs/btrfs/inode.c       | 105 ++++++++++++++++++++++++++++++++++-------
 fs/btrfs/super.c       |   2 +
 7 files changed, 119 insertions(+), 17 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 b15122aa26f9..7397db45eb36 100644
--- a/fs/btrfs/Makefile
+++ b/fs/btrfs/Makefile
@@ -38,6 +38,7 @@ btrfs-$(CONFIG_BTRFS_FS_POSIX_ACL) += acl.o
 btrfs-$(CONFIG_BTRFS_DEBUG) += 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/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 55c272fe5d92..81940b27b037 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -339,6 +339,10 @@ struct btrfs_inode {
 
 	struct rw_semaphore i_mmap_lock;
 
+#ifdef CONFIG_FS_ENCRYPTION
+	struct fscrypt_inode_info *i_crypt_info;
+#endif
+
 	struct inode vfs_inode;
 };
 
@@ -582,6 +586,7 @@ 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,
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index cf1cb5c4db75..8b0ebdeca9dd 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3813,6 +3813,9 @@ static int btrfs_file_open(struct inode *inode, struct file *filp)
 		return -EIO;
 
 	filp->f_mode |= FMODE_NOWAIT | FMODE_CAN_ODIRECT;
+	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..6cfba7d94e72
--- /dev/null
+++ b/fs/btrfs/fscrypt.c
@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "ctree.h"
+#include "btrfs_inode.h"
+#include "fscrypt.h"
+
+const struct fscrypt_operations btrfs_fscrypt_ops = {
+	.inode_info_offs = (int)offsetof(struct btrfs_inode, i_crypt_info) -
+			   (int)offsetof(struct btrfs_inode, vfs_inode),
+};
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 906d5c21ebc4..8f89e44b2d53 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5490,6 +5490,10 @@ static int btrfs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	if (ret)
 		return ret;
 
+	ret = fscrypt_prepare_setattr(dentry, attr);
+	if (ret)
+		return ret;
+
 	if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
 		ret = btrfs_setsize(inode, attr);
 		if (ret)
@@ -5746,6 +5750,7 @@ void btrfs_evict_inode(struct inode *inode)
 	 */
 	btrfs_remove_delayed_node(BTRFS_I(inode));
 clear_inode:
+	fscrypt_put_encryption_info(inode);
 	clear_inode(inode);
 }
 
@@ -6537,6 +6542,12 @@ int btrfs_new_inode_prepare(struct btrfs_new_inode_args *args,
 		return ret;
 	}
 
+	ret = fscrypt_prepare_new_inode(dir, inode, &args->encrypt);
+	if (ret) {
+		btrfs_new_inode_args_destroy(args);
+		return ret;
+	}
+
 	/* 1 to add inode item */
 	*trans_num_items = 1;
 	/* 1 to add compression property */
@@ -7048,9 +7059,13 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
 	if (inode->i_nlink >= BTRFS_LINK_MAX)
 		return -EMLINK;
 
+	ret = fscrypt_prepare_link(old_dentry, dir, dentry);
+	if (ret)
+		return ret;
+
 	ret = fscrypt_setup_filename(dir, &dentry->d_name, 0, &fname);
 	if (ret)
-		goto fail;
+		return ret;
 
 	ret = btrfs_set_inode_index(BTRFS_I(dir), &index);
 	if (ret)
@@ -8109,6 +8124,9 @@ struct inode *btrfs_alloc_inode(struct super_block *sb)
 	INIT_LIST_HEAD(&ei->delayed_iput);
 	init_rwsem(&ei->i_mmap_lock);
 
+#ifdef CONFIG_FS_ENCRYPTION
+	ei->i_crypt_info = NULL;
+#endif
 	return inode;
 }
 
@@ -8124,6 +8142,7 @@ void btrfs_test_destroy_inode(struct inode *inode)
 void btrfs_free_inode(struct inode *inode)
 {
 	kfree(BTRFS_I(inode)->file_extent_tree);
+	fscrypt_free_inode(inode);
 	kmem_cache_free(btrfs_inode_cachep, BTRFS_I(inode));
 }
 
@@ -8195,8 +8214,7 @@ 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 inode_generic_drop(inode);
+	return inode_generic_drop(inode) || fscrypt_drop_inode(inode);
 }
 
 static void init_once(void *foo)
@@ -8847,6 +8865,10 @@ static int btrfs_rename2(struct mnt_idmap *idmap, struct inode *old_dir,
 	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);
@@ -9041,20 +9063,28 @@ static int btrfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
 	};
 	unsigned int trans_num_items;
 	int ret;
-	int name_len;
 	int datasize;
 	unsigned long ptr;
 	struct btrfs_file_extent_item *ei;
 	struct extent_buffer *leaf;
+	struct fscrypt_str disk_link;
+	size_t max_len;
+	u32 name_len = strlen(symname);
+
+	/*
+	 * BTRFS_MAX_INLINE_DATA_SIZE() isn't actually telling the truth, we actually
+	 * limit inline data extents to min(BTRFS_MAX_INLINE_DATA_SIZE(), sectorsize),
+	 * so adjust max_len given this wonderful bit of inconsistency.
+	 */
+	max_len = min_t(size_t, BTRFS_MAX_INLINE_DATA_SIZE(fs_info), fs_info->sectorsize);
 
-	name_len = strlen(symname);
 	/*
-	 * Symlinks utilize uncompressed inline extent data, which should not
-	 * reach block size.
+	 * fscrypt sets disk_link.len to be len + 1, including a NUL terminator,
+	 * but we don't store that '\0' character.
 	 */
-	if (name_len > BTRFS_MAX_INLINE_DATA_SIZE(fs_info) ||
-	    name_len >= fs_info->sectorsize)
-		return -ENAMETOOLONG;
+	ret = fscrypt_prepare_symlink(dir, symname, name_len, max_len + 1, &disk_link);
+	if (ret)
+		return ret;
 
 	inode = new_inode(dir->i_sb);
 	if (!inode)
@@ -9063,8 +9093,8 @@ static int btrfs_symlink(struct mnt_idmap *idmap, 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);
-	inode_set_bytes(inode, name_len);
+	btrfs_i_size_write(BTRFS_I(inode), disk_link.len - 1);
+	inode_set_bytes(inode, disk_link.len - 1);
 
 	new_inode_args.inode = inode;
 	ret = btrfs_new_inode_prepare(&new_inode_args, &trans_num_items);
@@ -9091,17 +9121,29 @@ static int btrfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
 		inode = NULL;
 		goto out;
 	}
+
+	if (IS_ENCRYPTED(inode)) {
+		ret = fscrypt_encrypt_symlink(inode, symname, name_len, &disk_link);
+		if (ret) {
+			btrfs_abort_transaction(trans, ret);
+			btrfs_free_path(path);
+			discard_new_inode(inode);
+			inode = NULL;
+			goto out;
+		}
+	}
+
 	key.objectid = btrfs_ino(BTRFS_I(inode));
 	key.type = BTRFS_EXTENT_DATA_KEY;
 	key.offset = 0;
-	datasize = btrfs_file_extent_calc_inline_size(name_len);
+	datasize = btrfs_file_extent_calc_inline_size(disk_link.len - 1);
 	ret = btrfs_insert_empty_item(trans, root, path, &key, datasize);
 	if (unlikely(ret)) {
 		btrfs_abort_transaction(trans, ret);
 		btrfs_free_path(path);
 		discard_new_inode(inode);
 		inode = NULL;
-		goto out;
+		goto free_name;
 	}
 	leaf = path->nodes[0];
 	ei = btrfs_item_ptr(leaf, path->slots[0],
@@ -9112,14 +9154,17 @@ static int btrfs_symlink(struct mnt_idmap *idmap, 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);
-	btrfs_set_file_extent_ram_bytes(leaf, ei, name_len);
+	btrfs_set_file_extent_ram_bytes(leaf, ei, disk_link.len - 1);
 
 	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_free_path(path);
 
 	d_instantiate_new(dentry, inode);
 	ret = 0;
+free_name:
+	if (disk_link.name != (unsigned char *)symname)
+		kfree(disk_link.name);
 out:
 	btrfs_end_transaction(trans);
 	btrfs_btree_balance_dirty(fs_info);
@@ -9131,6 +9176,29 @@ static int btrfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
 	return ret;
 }
 
+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,
@@ -10762,7 +10830,7 @@ 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,
@@ -10772,4 +10840,7 @@ 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 b26aa9169e83..efaa0788c1fc 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -49,6 +49,7 @@
 #include "tests/btrfs-tests.h"
 #include "block-group.h"
 #include "discard.h"
+#include "fscrypt.h"
 #include "qgroup.h"
 #include "raid56.h"
 #include "fs.h"
@@ -969,6 +970,7 @@ 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;
 	sb->s_iflags |= SB_I_CGROUPWB | SB_I_ALLOW_HSM;
 
-- 
2.53.0