From: Omar Sandoval <osan...@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 <osan...@osandov.com>
Signed-off-by: Sweet Tea Dorminy <sweettea-ker...@dorminy.me>
Signed-off-by: Josef Bacik <jo...@toxicpanda.com>
---
 fs/btrfs/Makefile      |   1 +
 fs/btrfs/btrfs_inode.h |   1 +
 fs/btrfs/file.c        |   3 ++
 fs/btrfs/fscrypt.c     |   7 +++
 fs/btrfs/fscrypt.h     |  10 ++++
 fs/btrfs/inode.c       | 110 ++++++++++++++++++++++++++++++++++-------
 fs/btrfs/super.c       |   2 +
 7 files changed, 116 insertions(+), 18 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 525af975f61c..6e51d054c17a 100644
--- a/fs/btrfs/Makefile
+++ b/fs/btrfs/Makefile
@@ -39,6 +39,7 @@ btrfs-$(CONFIG_BTRFS_FS_POSIX_ACL) += acl.o
 btrfs-$(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/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index bebb5921b922..052072373078 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -455,6 +455,7 @@ 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 92419cb8508a..26905b77c7e8 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)
 
        filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC | FMODE_BUF_WASYNC |
                        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..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 4806ff34224a..b92da4a4ed21 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5053,6 +5053,10 @@ static int btrfs_setattr(struct mnt_idmap *idmap, struct 
dentry *dentry,
        if (err)
                return err;
 
+       err = fscrypt_prepare_setattr(dentry, attr);
+       if (err)
+               return err;
+
        if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
                err = btrfs_setsize(inode, attr);
                if (err)
@@ -5207,11 +5211,8 @@ void btrfs_evict_inode(struct inode *inode)
 
        trace_btrfs_inode_evict(inode);
 
-       if (!root) {
-               fsverity_cleanup_inode(inode);
-               clear_inode(inode);
-               return;
-       }
+       if (!root)
+               goto cleanup;
 
        evict_inode_truncate_pages(inode);
 
@@ -5311,6 +5312,9 @@ void btrfs_evict_inode(struct inode *inode)
         * to retry these periodically in the future.
         */
        btrfs_remove_delayed_node(BTRFS_I(inode));
+
+cleanup:
+       fscrypt_put_encryption_info(inode);
        fsverity_cleanup_inode(inode);
        clear_inode(inode);
 }
@@ -6096,6 +6100,12 @@ int btrfs_new_inode_prepare(struct btrfs_new_inode_args 
*args,
                return ret;
        }
 
+       ret = fscrypt_prepare_new_inode(dir, inode, &args->encrypt);
+       if (ret) {
+               fscrypt_free_filename(&args->fname);
+               return ret;
+       }
+
        /* 1 to add inode item */
        *trans_num_items = 1;
        /* 1 to add compression property */
@@ -6569,9 +6579,13 @@ 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)
@@ -8519,6 +8533,7 @@ 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));
 }
 
@@ -8589,8 +8604,7 @@ 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)
@@ -9170,6 +9184,11 @@ 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);
@@ -9384,15 +9403,31 @@ static int btrfs_symlink(struct mnt_idmap *idmap, 
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;
+       size_t max_len;
+       u32 name_len = strlen(symname);
 
-       name_len = strlen(symname);
-       if (name_len > BTRFS_MAX_INLINE_DATA_SIZE(fs_info))
-               return -ENAMETOOLONG;
+       /*
+        * 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);
+
+       /*
+        * 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, max_len + 1,
+                                     &disk_link);
+       if (err)
+               return err;
 
        inode = new_inode(dir->i_sb);
        if (!inode)
@@ -9401,8 +9436,8 @@ 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;
        err = btrfs_new_inode_prepare(&new_inode_args, &trans_num_items);
@@ -9429,10 +9464,23 @@ static int btrfs_symlink(struct mnt_idmap *idmap, 
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) {
@@ -9451,10 +9499,10 @@ 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_mark_buffer_dirty(trans, leaf);
        btrfs_free_path(path);
 
@@ -9471,6 +9519,29 @@ static int btrfs_symlink(struct mnt_idmap *idmap, 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,
@@ -10949,7 +11020,7 @@ 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,
@@ -10959,4 +11030,7 @@ 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 08761a5c9cc3..0d88f871ba09 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"
@@ -1103,6 +1104,7 @@ 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;
-- 
2.41.0

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