eCryptfs: Fix data corruption when using ecryptfs_passthrough

ecryptfs_passthrough is a mount option that allows eCryptfs to allow
data to be written to non-eCryptfs files in the lower filesystem.  The
passthrough option was causing data corruption due to it not always
being treated as a non-eCryptfs file.

The first 8 bytes of an eCryptfs file contains the decrypted file size.
This value was being written to the non-eCryptfs files, too.  Also,
extra 0x00 characters were being written to make the file size a
multiple of PAGE_CACHE_SIZE.

Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 55b3145..5ed86e2 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -814,6 +814,13 @@ int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
 		size_t num_zeros = (PAGE_CACHE_SIZE
 				    - (new_length & ~PAGE_CACHE_MASK));
 
+		if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
+			rc = vmtruncate(inode, new_length);
+			if (rc)
+				goto out_free;
+			rc = vmtruncate(lower_dentry->d_inode, new_length);
+			goto out_free;
+		}
 		if (num_zeros) {
 			char *zeros_virt;
 
@@ -915,8 +922,6 @@ static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
 			}
 			rc = 0;
 			crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
-			mutex_unlock(&crypt_stat->cs_mutex);
-			goto out;
 		}
 	}
 	mutex_unlock(&crypt_stat->cs_mutex);