[PATCH] ecryptfs: fs/Makefile and fs/Kconfig

eCryptfs is a stacked cryptographic filesystem for Linux.  It is derived from
Erez Zadok's Cryptfs, implemented through the FiST framework for generating
stacked filesystems.  eCryptfs extends Cryptfs to provide advanced key
management and policy features.  eCryptfs stores cryptographic metadata in the
header of each file written, so that encrypted files can be copied between
hosts; the file will be decryptable with the proper key, and there is no need
to keep track of any additional information aside from what is already in the
encrypted file itself.

[akpm@osdl.org: updates for ongoing API changes]
[bunk@stusta.de: cleanups]
[akpm@osdl.org: alpha build fix]
[akpm@osdl.org: cleanups]
[tytso@mit.edu: inode-diet updates]
[pbadari@us.ibm.com: generic_file_*_read/write() interface updates]
[rdunlap@xenotime.net: printk format fixes]
[akpm@osdl.org: make slab creation and teardown table-driven]
Signed-off-by: Phillip Hellewell <phillip@hellewell.homeip.net>
Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 198 insertions, 0 deletions

diff --git a/fs/ecryptfs/super.c b/fs/ecryptfs/super.c
new file mode 100644
index 0000000..c337c04
--- /dev/null
+++ b/fs/ecryptfs/super.c
@@ -0,0 +1,198 @@
+/**
+ * eCryptfs: Linux filesystem encryption layer
+ *
+ * Copyright (C) 1997-2003 Erez Zadok
+ * Copyright (C) 2001-2003 Stony Brook University
+ * Copyright (C) 2004-2006 International Business Machines Corp.
+ *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
+ *              Michael C. Thompson <mcthomps@us.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/key.h>
+#include <linux/seq_file.h>
+#include <linux/crypto.h>
+#include "ecryptfs_kernel.h"
+
+struct kmem_cache *ecryptfs_inode_info_cache;
+
+/**
+ * ecryptfs_alloc_inode - allocate an ecryptfs inode
+ * @sb: Pointer to the ecryptfs super block
+ *
+ * Called to bring an inode into existence.
+ *
+ * Only handle allocation, setting up structures should be done in
+ * ecryptfs_read_inode. This is because the kernel, between now and
+ * then, will 0 out the private data pointer.
+ *
+ * Returns a pointer to a newly allocated inode, NULL otherwise
+ */
+static struct inode *ecryptfs_alloc_inode(struct super_block *sb)
+{
+	struct ecryptfs_inode_info *ecryptfs_inode;
+	struct inode *inode = NULL;
+
+	ecryptfs_inode = kmem_cache_alloc(ecryptfs_inode_info_cache,
+					  SLAB_KERNEL);
+	if (unlikely(!ecryptfs_inode))
+		goto out;
+	ecryptfs_init_crypt_stat(&ecryptfs_inode->crypt_stat);
+	inode = &ecryptfs_inode->vfs_inode;
+out:
+	return inode;
+}
+
+/**
+ * ecryptfs_destroy_inode
+ * @inode: The ecryptfs inode
+ *
+ * This is used during the final destruction of the inode.
+ * All allocation of memory related to the inode, including allocated
+ * memory in the crypt_stat struct, will be released here.
+ * There should be no chance that this deallocation will be missed.
+ */
+static void ecryptfs_destroy_inode(struct inode *inode)
+{
+	struct ecryptfs_inode_info *inode_info;
+
+	inode_info = ecryptfs_inode_to_private(inode);
+	ecryptfs_destruct_crypt_stat(&inode_info->crypt_stat);
+	kmem_cache_free(ecryptfs_inode_info_cache, inode_info);
+}
+
+/**
+ * ecryptfs_init_inode
+ * @inode: The ecryptfs inode
+ *
+ * Set up the ecryptfs inode.
+ */
+void ecryptfs_init_inode(struct inode *inode, struct inode *lower_inode)
+{
+	ecryptfs_set_inode_lower(inode, lower_inode);
+	inode->i_ino = lower_inode->i_ino;
+	inode->i_version++;
+	inode->i_op = &ecryptfs_main_iops;
+	inode->i_fop = &ecryptfs_main_fops;
+	inode->i_mapping->a_ops = &ecryptfs_aops;
+}
+
+/**
+ * ecryptfs_put_super
+ * @sb: Pointer to the ecryptfs super block
+ *
+ * Final actions when unmounting a file system.
+ * This will handle deallocation and release of our private data.
+ */
+static void ecryptfs_put_super(struct super_block *sb)
+{
+	struct ecryptfs_sb_info *sb_info = ecryptfs_superblock_to_private(sb);
+
+	ecryptfs_destruct_mount_crypt_stat(&sb_info->mount_crypt_stat);
+	kmem_cache_free(ecryptfs_sb_info_cache, sb_info);
+	ecryptfs_set_superblock_private(sb, NULL);
+}
+
+/**
+ * ecryptfs_statfs
+ * @sb: The ecryptfs super block
+ * @buf: The struct kstatfs to fill in with stats
+ *
+ * Get the filesystem statistics. Currently, we let this pass right through
+ * to the lower filesystem and take no action ourselves.
+ */
+static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	return vfs_statfs(ecryptfs_dentry_to_lower(dentry), buf);
+}
+
+/**
+ * ecryptfs_clear_inode
+ * @inode - The ecryptfs inode
+ *
+ * Called by iput() when the inode reference count reached zero
+ * and the inode is not hashed anywhere.  Used to clear anything
+ * that needs to be, before the inode is completely destroyed and put
+ * on the inode free list. We use this to drop out reference to the
+ * lower inode.
+ */
+static void ecryptfs_clear_inode(struct inode *inode)
+{
+	iput(ecryptfs_inode_to_lower(inode));
+}
+
+/**
+ * ecryptfs_umount_begin
+ *
+ * Called in do_umount().
+ */
+static void ecryptfs_umount_begin(struct vfsmount *vfsmnt, int flags)
+{
+	struct vfsmount *lower_mnt =
+		ecryptfs_dentry_to_lower_mnt(vfsmnt->mnt_sb->s_root);
+	struct super_block *lower_sb;
+
+	mntput(lower_mnt);
+	lower_sb = lower_mnt->mnt_sb;
+	if (lower_sb->s_op->umount_begin)
+		lower_sb->s_op->umount_begin(lower_mnt, flags);
+}
+
+/**
+ * ecryptfs_show_options
+ *
+ * Prints the directory we are currently mounted over.
+ * Returns zero on success; non-zero otherwise
+ */
+static int ecryptfs_show_options(struct seq_file *m, struct vfsmount *mnt)
+{
+	struct super_block *sb = mnt->mnt_sb;
+	struct dentry *lower_root_dentry = ecryptfs_dentry_to_lower(sb->s_root);
+	struct vfsmount *lower_mnt = ecryptfs_dentry_to_lower_mnt(sb->s_root);
+	char *tmp_page;
+	char *path;
+	int rc = 0;
+
+	tmp_page = (char *)__get_free_page(GFP_KERNEL);
+	if (!tmp_page) {
+		rc = -ENOMEM;
+		goto out;
+	}
+	path = d_path(lower_root_dentry, lower_mnt, tmp_page, PAGE_SIZE);
+	if (IS_ERR(path)) {
+		rc = PTR_ERR(path);
+		goto out;
+	}
+	seq_printf(m, ",dir=%s", path);
+	free_page((unsigned long)tmp_page);
+out:
+	return rc;
+}
+
+struct super_operations ecryptfs_sops = {
+	.alloc_inode = ecryptfs_alloc_inode,
+	.destroy_inode = ecryptfs_destroy_inode,
+	.drop_inode = generic_delete_inode,
+	.put_super = ecryptfs_put_super,
+	.statfs = ecryptfs_statfs,
+	.remount_fs = NULL,
+	.clear_inode = ecryptfs_clear_inode,
+	.umount_begin = ecryptfs_umount_begin,
+	.show_options = ecryptfs_show_options
+};