From: Eric Biggers <ebiggers@xxxxxxxxxx>
Currently, filesystems allow truncate(2) on an encrypted file without
the encryption key. However, it's impossible to correctly handle the
case where the size being truncated to is not a multiple of the
filesystem block size, because that would require decrypting the final
block, zeroing the part beyond i_size, then encrypting the block.
As other modifications to encrypted file contents are prohibited without
the key, just prohibit truncate(2) as well, making it fail with ENOKEY.
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
fs/f2fs/file.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 61af721329fa..be0b32bd1297 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -682,9 +682,13 @@ int f2fs_setattr(struct dentry *dentry, struct iattr *attr)
return err;
if (attr->ia_valid & ATTR_SIZE) {
- if (f2fs_encrypted_inode(inode) &&
- fscrypt_get_encryption_info(inode))
- return -EACCES;
+ if (f2fs_encrypted_inode(inode)) {
+ err = fscrypt_get_encryption_info(inode);
+ if (err)
+ return err;
+ if (!fscrypt_has_encryption_key(inode))
+ return -ENOKEY;
+ }
if (attr->ia_size <= i_size_read(inode)) {
truncate_setsize(inode, attr->ia_size);
--
2.13.1.508.gb3defc5cc-goog
