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Date: Fri, 7 Oct 2011 00:11:03 -0700
From: Allison Henderson <achender@...ux.vnet.ibm.com>
To: linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org
Cc: Allison Henderson <achender@...ux.vnet.ibm.com>
Subject: [Ext4 Secure Delete 5/7v4] ext4: Secure Delete: Secure delete directory entry
This patch zeros or randomizes a files directory entry when a file
with the EXT4_SECRM_FL attribute flag is deleted or renamed. A new
flag parameter has been added to the ext4_delete_entry routine,
that will cause the entry to be securely zeroed or randomized and
then flushed to the disk.
Signed-off-by: Allison Henderson <achender@...ux.vnet.ibm.com>
---
v1->v2
Removed new inode parameter in ext4_delete_entry and replaced
with a new flag for ext4_delete_entry
:100644 100644 34f82a1... 0cba63b... M fs/ext4/ext4.h
:100644 100644 f8068c7... b3479c6... M fs/ext4/namei.c
fs/ext4/ext4.h | 6 +++++
fs/ext4/namei.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++-------
2 files changed, 62 insertions(+), 8 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 34f82a1..0cba63b 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -532,6 +532,12 @@ struct ext4_new_group_data {
#define EXT4_FREE_BLOCKS_NO_QUOT_UPDATE 0x0008
/*
+ * Flags used by ext4_delete_entry
+ */
+#define EXT4_DEL_ENTRY_ZERO 0x0001
+#define EXT4_DEL_ENTRY_RAND 0x0002
+
+/*
* ioctl commands
*/
#define EXT4_IOC_GETFLAGS FS_IOC_GETFLAGS
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index f8068c7..b3479c6 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -34,6 +34,7 @@
#include <linux/quotaops.h>
#include <linux/buffer_head.h>
#include <linux/bio.h>
+#include <linux/random.h>
#include "ext4.h"
#include "ext4_jbd2.h"
@@ -1639,9 +1640,11 @@ cleanup:
static int ext4_delete_entry(handle_t *handle,
struct inode *dir,
struct ext4_dir_entry_2 *de_del,
- struct buffer_head *bh)
+ struct buffer_head *bh,
+ int flags)
{
struct ext4_dir_entry_2 *de, *pde;
+ struct ext4_super_block *es = EXT4_SB(dir->i_sb)->s_es;
unsigned int blocksize = dir->i_sb->s_blocksize;
int i, err;
@@ -1669,7 +1672,38 @@ static int ext4_delete_entry(handle_t *handle,
de->inode = 0;
dir->i_version++;
BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
- err = ext4_handle_dirty_metadata(handle, dir, bh);
+
+ /*
+ * If the secure remove flag is on, zero
+ * or randomize the entry and write it out
+ * to the disk
+ */
+ if (flags & EXT4_DEL_ENTRY_ZERO) {
+ memset(de->name, 0x00, de->name_len);
+ de->file_type = 0;
+ } else if (flags & EXT4_DEL_ENTRY_RAND) {
+ get_random_bytes(de->name, de->name_len);
+ get_random_bytes(&(de->file_type),
+ sizeof(de->file_type));
+ }
+
+ if (flags & EXT4_DEL_ENTRY_ZERO ||
+ flags & EXT4_DEL_ENTRY_RAND) {
+
+ set_buffer_dirty(bh);
+ sync_dirty_buffer(bh);
+ if (buffer_req(bh) && !buffer_uptodate(bh)) {
+ es->s_last_error_block =
+ cpu_to_le64(bh->b_blocknr);
+ ext4_error_inode(dir, __func__,
+ __LINE__, bh->b_blocknr,
+ "IO error syncing itable block");
+ err = -EIO;
+ }
+ } else
+ err = ext4_handle_dirty_metadata(handle,
+ dir, bh);
+
if (unlikely(err)) {
ext4_std_error(dir->i_sb, err);
return err;
@@ -2151,7 +2185,7 @@ static int ext4_rmdir(struct inode *dir, struct dentry *dentry)
if (!empty_dir(inode))
goto end_rmdir;
- retval = ext4_delete_entry(handle, dir, de, bh);
+ retval = ext4_delete_entry(handle, dir, de, bh, 0);
if (retval)
goto end_rmdir;
if (!EXT4_DIR_LINK_EMPTY(inode))
@@ -2179,7 +2213,7 @@ end_rmdir:
static int ext4_unlink(struct inode *dir, struct dentry *dentry)
{
- int retval;
+ int retval, del_entry_flags;
struct inode *inode;
struct buffer_head *bh;
struct ext4_dir_entry_2 *de;
@@ -2204,6 +2238,13 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
goto end_unlink;
inode = dentry->d_inode;
+ del_entry_flags = 0;
+ if (EXT4_I(inode)->i_flags & EXT4_SECRM_FL) {
+ if (EXT4_I(inode)->i_flags & EXT4_SECRM_RANDOM_FL)
+ del_entry_flags = EXT4_DEL_ENTRY_RAND;
+ else
+ del_entry_flags = EXT4_DEL_ENTRY_ZERO;
+ }
retval = -EIO;
if (le32_to_cpu(de->inode) != inode->i_ino)
@@ -2215,7 +2256,7 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
inode->i_ino, inode->i_nlink);
inode->i_nlink = 1;
}
- retval = ext4_delete_entry(handle, dir, de, bh);
+ retval = ext4_delete_entry(handle, dir, de, bh, del_entry_flags);
if (retval)
goto end_unlink;
dir->i_ctime = dir->i_mtime = ext4_current_time(dir);
@@ -2395,7 +2436,7 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *old_inode, *new_inode;
struct buffer_head *old_bh, *new_bh, *dir_bh;
struct ext4_dir_entry_2 *old_de, *new_de;
- int retval, force_da_alloc = 0;
+ int retval, del_entry_flags, force_da_alloc = 0;
dquot_initialize(old_dir);
dquot_initialize(new_dir);
@@ -2494,11 +2535,18 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
/*
* ok, that's it
*/
+ del_entry_flags = 0;
+ if (EXT4_I(old_inode)->i_flags & EXT4_SECRM_FL) {
+ if (EXT4_I(old_inode)->i_flags & EXT4_SECRM_RANDOM_FL)
+ del_entry_flags = EXT4_DEL_ENTRY_RAND;
+ else
+ del_entry_flags = EXT4_DEL_ENTRY_ZERO;
+ }
if (le32_to_cpu(old_de->inode) != old_inode->i_ino ||
old_de->name_len != old_dentry->d_name.len ||
strncmp(old_de->name, old_dentry->d_name.name, old_de->name_len) ||
(retval = ext4_delete_entry(handle, old_dir,
- old_de, old_bh)) == -ENOENT) {
+ old_de, old_bh, del_entry_flags)) == -ENOENT) {
/* old_de could have moved from under us during htree split, so
* make sure that we are deleting the right entry. We might
* also be pointing to a stale entry in the unused part of
@@ -2509,7 +2557,7 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
old_bh2 = ext4_find_entry(old_dir, &old_dentry->d_name, &old_de2);
if (old_bh2) {
retval = ext4_delete_entry(handle, old_dir,
- old_de2, old_bh2);
+ old_de2, old_bh2, del_entry_flags);
brelse(old_bh2);
}
}
--
1.7.1
--
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