[PATCH v6 37/43] btrfs: decrypt file names for send

[Daniel Vacek <neelx@suse.com>]

From: Josef Bacik <josef@toxicpanda.com>

In send we're going to be looking up file names from back references and
putting them into the send stream.  If we are encrypted use the helper
for decrypting names and copy the decrypted name into the buffer.

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

v5: https://lore.kernel.org/linux-btrfs/fd8b1d5f395a890dbdf8281a52fbaaa920c7b726.1706116485.git.josef@toxicpanda.com/
 * Simplified the error return logic in fs_path_add_from_encrypted().
---
 fs/btrfs/send.c | 47 +++++++++++++++++++++++++++++++++++++----------
 1 file changed, 37 insertions(+), 10 deletions(-)

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index b77f96ae2fea..faaade4c35dc 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -32,6 +32,7 @@
 #include "ioctl.h"
 #include "verity.h"
 #include "lru_cache.h"
+#include "fscrypt.h"
 
 /*
  * Maximum number of references an extent can have in order for us to attempt to
@@ -579,13 +580,39 @@ static inline int fs_path_add_path(struct fs_path *p, const struct fs_path *p2)
 	return fs_path_add(p, p2->start, fs_path_len(p2));
 }
 
-static int fs_path_add_from_extent_buffer(struct fs_path *p,
+static int fs_path_add_from_encrypted(struct btrfs_root *root,
+				      struct fs_path *p,
+				      struct extent_buffer *eb,
+				      unsigned long off, int len,
+				      u64 parent_ino)
+{
+	struct fscrypt_str fname = FSTR_INIT(NULL, 0);
+	int ret;
+
+	ret = fscrypt_fname_alloc_buffer(BTRFS_NAME_LEN, &fname);
+	if (ret)
+		return ret;
+
+	ret = btrfs_decrypt_name(root, eb, off, len, parent_ino, &fname);
+	if (!ret)
+		ret = fs_path_add(p, fname.name, fname.len);
+
+	fscrypt_fname_free_buffer(&fname);
+	return ret;
+}
+
+static int fs_path_add_from_extent_buffer(struct btrfs_root *root,
+					  struct fs_path *p,
 					  struct extent_buffer *eb,
-					  unsigned long off, int len)
+					  unsigned long off, int len,
+					  u64 parent_ino)
 {
 	int ret;
 	char *prepared;
 
+	if (root && btrfs_fs_incompat(root->fs_info, ENCRYPT))
+		return fs_path_add_from_encrypted(root, p, eb, off, len, parent_ino);
+
 	ret = fs_path_prepare_for_add(p, len, &prepared);
 	if (ret < 0)
 		return ret;
@@ -1062,8 +1089,7 @@ static int iterate_inode_ref(struct btrfs_root *root, struct btrfs_path *path,
 			}
 			p->start = start;
 		} else {
-			ret = fs_path_add_from_extent_buffer(p, eb, name_off,
-							     name_len);
+			ret = fs_path_add_from_extent_buffer(root, p, eb, name_off, name_len, dir);
 			if (ret < 0)
 				goto out;
 		}
@@ -1759,7 +1785,7 @@ static int read_symlink_unencrypted(struct btrfs_root *root, u64 ino, struct fs_
 	off = btrfs_file_extent_inline_start(ei);
 	len = btrfs_file_extent_ram_bytes(path->nodes[0], ei);
 
-	return fs_path_add_from_extent_buffer(dest, path->nodes[0], off, len);
+	return fs_path_add_from_extent_buffer(NULL, dest, path->nodes[0], off, len, 0);
 }
 
 static int read_symlink_encrypted(struct btrfs_root *root, u64 ino, struct fs_path *dest)
@@ -2034,18 +2060,19 @@ static int get_first_ref(struct btrfs_root *root, u64 ino,
 		iref = btrfs_item_ptr(path->nodes[0], path->slots[0],
 				      struct btrfs_inode_ref);
 		len = btrfs_inode_ref_name_len(path->nodes[0], iref);
-		ret = fs_path_add_from_extent_buffer(name, path->nodes[0],
-						     (unsigned long)(iref + 1),
-						     len);
 		parent_dir = found_key.offset;
+		ret = fs_path_add_from_extent_buffer(root, name, path->nodes[0],
+						     (unsigned long)(iref + 1),
+						     len, parent_dir);
 	} else {
 		struct btrfs_inode_extref *extref;
 		extref = btrfs_item_ptr(path->nodes[0], path->slots[0],
 					struct btrfs_inode_extref);
 		len = btrfs_inode_extref_name_len(path->nodes[0], extref);
-		ret = fs_path_add_from_extent_buffer(name, path->nodes[0],
-					(unsigned long)&extref->name, len);
 		parent_dir = btrfs_inode_extref_parent(path->nodes[0], extref);
+		ret = fs_path_add_from_extent_buffer(root, name, path->nodes[0],
+					(unsigned long)&extref->name, len,
+					parent_dir);
 	}
 	if (ret < 0)
 		return ret;
-- 
2.51.0