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Commit bd4f0fe8 authored by Tyler Hicks's avatar Tyler Hicks
Browse files

eCryptfs: Remove unnecessary grow_file() function 



When creating a new eCryptfs file, the crypto metadata is written out
and then the lower file was being "grown" with 4 kB of encrypted zeroes.
I suspect that growing the encrypted file was to prevent an information
leak that the unencrypted file was empty. However, the unencrypted file
size is stored, in plaintext, in the metadata so growing the file is
unnecessary.

Signed-off-by: default avatarTyler Hicks <tyhicks@linux.vnet.ibm.com>
parent 40471856

fs/ecryptfs/crypto.c

+1 −0
Original line number Diff line number Diff line
@@ -1389,6 +1389,7 @@ int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry) 
		rc = -ENOMEM;

		goto out;

	}

	/* Zeroed page ensures the in-header unencrypted i_size is set to 0 */

	rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,

					 ecryptfs_dentry);

	if (unlikely(rc)) {

fs/ecryptfs/inode.c

+0 −23
Original line number Diff line number Diff line
@@ -142,26 +142,6 @@ ecryptfs_do_create(struct inode *directory_inode, 
	return rc;

}



/**

 * grow_file

 * @ecryptfs_dentry: the eCryptfs dentry

 *

 * This is the code which will grow the file to its correct size.

 */

static int grow_file(struct dentry *ecryptfs_dentry)

{

	struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;

	char zero_virt[] = { 0x00 };

	int rc = 0;



	rc = ecryptfs_write(ecryptfs_inode, zero_virt, 0, 1);

	i_size_write(ecryptfs_inode, 0);

	rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);

	ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat.flags |=

		ECRYPTFS_NEW_FILE;

	return rc;

}



/**

 * ecryptfs_initialize_file

 *
@@ -202,9 +182,6 @@ static int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry) 
		printk(KERN_ERR "Error writing headers; rc = [%d]\n", rc);

		goto out;

	}

	rc = grow_file(ecryptfs_dentry);

	if (rc)

		printk(KERN_ERR "Error growing file; rc = [%d]\n", rc);

out:

	return rc;

}