Merge branch 'linus' into x86/signal

[linux-2.6] / fs / ecryptfs / inode.c

/**
 * eCryptfs: Linux filesystem encryption layer
 *
 * Copyright (C) 1997-2004 Erez Zadok
 * Copyright (C) 2001-2004 Stony Brook University
 * Copyright (C) 2004-2007 International Business Machines Corp.
 *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
 *              Michael C. Thompsion <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/file.h>
#include <linux/vmalloc.h>
#include <linux/pagemap.h>
#include <linux/dcache.h>
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/crypto.h>
#include <linux/fs_stack.h>
#include <asm/unaligned.h>
#include "ecryptfs_kernel.h"

static struct dentry *lock_parent(struct dentry *dentry)
{
        struct dentry *dir;

        dir = dget_parent(dentry);
        mutex_lock_nested(&(dir->d_inode->i_mutex), I_MUTEX_PARENT);
        return dir;
}

static void unlock_dir(struct dentry *dir)
{
        mutex_unlock(&dir->d_inode->i_mutex);
        dput(dir);
}

/**
 * ecryptfs_create_underlying_file
 * @lower_dir_inode: inode of the parent in the lower fs of the new file
 * @lower_dentry: New file's dentry in the lower fs
 * @ecryptfs_dentry: New file's dentry in ecryptfs
 * @mode: The mode of the new file
 * @nd: nameidata of ecryptfs' parent's dentry & vfsmount
 *
 * Creates the file in the lower file system.
 *
 * Returns zero on success; non-zero on error condition
 */
static int
ecryptfs_create_underlying_file(struct inode *lower_dir_inode,
                                struct dentry *dentry, int mode,
                                struct nameidata *nd)
{
        struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
        struct vfsmount *lower_mnt = ecryptfs_dentry_to_lower_mnt(dentry);
        struct dentry *dentry_save;
        struct vfsmount *vfsmount_save;
        int rc;

        dentry_save = nd->path.dentry;
        vfsmount_save = nd->path.mnt;
        nd->path.dentry = lower_dentry;
        nd->path.mnt = lower_mnt;
        rc = vfs_create(lower_dir_inode, lower_dentry, mode, nd);
        nd->path.dentry = dentry_save;
        nd->path.mnt = vfsmount_save;
        return rc;
}

/**
 * ecryptfs_do_create
 * @directory_inode: inode of the new file's dentry's parent in ecryptfs
 * @ecryptfs_dentry: New file's dentry in ecryptfs
 * @mode: The mode of the new file
 * @nd: nameidata of ecryptfs' parent's dentry & vfsmount
 *
 * Creates the underlying file and the eCryptfs inode which will link to
 * it. It will also update the eCryptfs directory inode to mimic the
 * stat of the lower directory inode.
 *
 * Returns zero on success; non-zero on error condition
 */
static int
ecryptfs_do_create(struct inode *directory_inode,
                   struct dentry *ecryptfs_dentry, int mode,
                   struct nameidata *nd)
{
        int rc;
        struct dentry *lower_dentry;
        struct dentry *lower_dir_dentry;

        lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
        lower_dir_dentry = lock_parent(lower_dentry);
        if (IS_ERR(lower_dir_dentry)) {
                ecryptfs_printk(KERN_ERR, "Error locking directory of "
                                "dentry\n");
                rc = PTR_ERR(lower_dir_dentry);
                goto out;
        }
        rc = ecryptfs_create_underlying_file(lower_dir_dentry->d_inode,
                                             ecryptfs_dentry, mode, nd);
        if (rc) {
                printk(KERN_ERR "%s: Failure to create dentry in lower fs; "
                       "rc = [%d]\n", __func__, rc);
                goto out_lock;
        }
        rc = ecryptfs_interpose(lower_dentry, ecryptfs_dentry,
                                directory_inode->i_sb, 0);
        if (rc) {
                ecryptfs_printk(KERN_ERR, "Failure in ecryptfs_interpose\n");
                goto out_lock;
        }
        fsstack_copy_attr_times(directory_inode, lower_dir_dentry->d_inode);
        fsstack_copy_inode_size(directory_inode, lower_dir_dentry->d_inode);
out_lock:
        unlock_dir(lower_dir_dentry);
out:
        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;
        struct file fake_file;
        struct ecryptfs_file_info tmp_file_info;
        char zero_virt[] = { 0x00 };
        int rc = 0;

        memset(&fake_file, 0, sizeof(fake_file));
        fake_file.f_path.dentry = ecryptfs_dentry;
        memset(&tmp_file_info, 0, sizeof(tmp_file_info));
        ecryptfs_set_file_private(&fake_file, &tmp_file_info);
        ecryptfs_set_file_lower(
                &fake_file,
                ecryptfs_inode_to_private(ecryptfs_inode)->lower_file);
        rc = ecryptfs_write(&fake_file, 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
 *
 * Cause the file to be changed from a basic empty file to an ecryptfs
 * file with a header and first data page.
 *
 * Returns zero on success
 */
static int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry)
{
        struct ecryptfs_crypt_stat *crypt_stat =
                &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
        int rc = 0;

        if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
                ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
                crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
                goto out;
        }
        crypt_stat->flags |= ECRYPTFS_NEW_FILE;
        ecryptfs_printk(KERN_DEBUG, "Initializing crypto context\n");
        rc = ecryptfs_new_file_context(ecryptfs_dentry);
        if (rc) {
                ecryptfs_printk(KERN_ERR, "Error creating new file "
                                "context; rc = [%d]\n", rc);
                goto out;
        }
        if (!ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->lower_file) {
                rc = ecryptfs_init_persistent_file(ecryptfs_dentry);
                if (rc) {
                        printk(KERN_ERR "%s: Error attempting to initialize "
                               "the persistent file for the dentry with name "
                               "[%s]; rc = [%d]\n", __func__,
                               ecryptfs_dentry->d_name.name, rc);
                        goto out;
                }
        }
        rc = ecryptfs_write_metadata(ecryptfs_dentry);
        if (rc) {
                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;
}

/**
 * ecryptfs_create
 * @dir: The inode of the directory in which to create the file.
 * @dentry: The eCryptfs dentry
 * @mode: The mode of the new file.
 * @nd: nameidata
 *
 * Creates a new file.
 *
 * Returns zero on success; non-zero on error condition
 */
static int
ecryptfs_create(struct inode *directory_inode, struct dentry *ecryptfs_dentry,
                int mode, struct nameidata *nd)
{
        int rc;

        /* ecryptfs_do_create() calls ecryptfs_interpose(), which opens
         * the crypt_stat->lower_file (persistent file) */
        rc = ecryptfs_do_create(directory_inode, ecryptfs_dentry, mode, nd);
        if (unlikely(rc)) {
                ecryptfs_printk(KERN_WARNING, "Failed to create file in"
                                "lower filesystem\n");
                goto out;
        }
        /* At this point, a file exists on "disk"; we need to make sure
         * that this on disk file is prepared to be an ecryptfs file */
        rc = ecryptfs_initialize_file(ecryptfs_dentry);
out:
        return rc;
}

/**
 * ecryptfs_lookup
 * @dir: inode
 * @dentry: The dentry
 * @nd: nameidata, may be NULL
 *
 * Find a file on disk. If the file does not exist, then we'll add it to the
 * dentry cache and continue on to read it from the disk.
 */
static struct dentry *ecryptfs_lookup(struct inode *dir, struct dentry *dentry,
                                      struct nameidata *nd)
{
        int rc = 0;
        struct dentry *lower_dir_dentry;
        struct dentry *lower_dentry;
        struct vfsmount *lower_mnt;
        char *encoded_name;
        int encoded_namelen;
        struct ecryptfs_crypt_stat *crypt_stat = NULL;
        struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
        char *page_virt = NULL;
        struct inode *lower_inode;
        u64 file_size;

        lower_dir_dentry = ecryptfs_dentry_to_lower(dentry->d_parent);
        dentry->d_op = &ecryptfs_dops;
        if ((dentry->d_name.len == 1 && !strcmp(dentry->d_name.name, "."))
            || (dentry->d_name.len == 2
                && !strcmp(dentry->d_name.name, ".."))) {
                d_drop(dentry);
                goto out;
        }
        encoded_namelen = ecryptfs_encode_filename(crypt_stat,
                                                   dentry->d_name.name,
                                                   dentry->d_name.len,
                                                   &encoded_name);
        if (encoded_namelen < 0) {
                rc = encoded_namelen;
                d_drop(dentry);
                goto out;
        }
        ecryptfs_printk(KERN_DEBUG, "encoded_name = [%s]; encoded_namelen "
                        "= [%d]\n", encoded_name, encoded_namelen);
        lower_dentry = lookup_one_len(encoded_name, lower_dir_dentry,
                                      encoded_namelen - 1);
        kfree(encoded_name);
        if (IS_ERR(lower_dentry)) {
                ecryptfs_printk(KERN_ERR, "ERR from lower_dentry\n");
                rc = PTR_ERR(lower_dentry);
                d_drop(dentry);
                goto out;
        }
        lower_mnt = mntget(ecryptfs_dentry_to_lower_mnt(dentry->d_parent));
        ecryptfs_printk(KERN_DEBUG, "lower_dentry = [%p]; lower_dentry->"
                "d_name.name = [%s]\n", lower_dentry,
                lower_dentry->d_name.name);
        lower_inode = lower_dentry->d_inode;
        fsstack_copy_attr_atime(dir, lower_dir_dentry->d_inode);
        BUG_ON(!atomic_read(&lower_dentry->d_count));
        ecryptfs_set_dentry_private(dentry,
                                    kmem_cache_alloc(ecryptfs_dentry_info_cache,
                                                     GFP_KERNEL));
        if (!ecryptfs_dentry_to_private(dentry)) {
                rc = -ENOMEM;
                ecryptfs_printk(KERN_ERR, "Out of memory whilst attempting "
                                "to allocate ecryptfs_dentry_info struct\n");
                goto out_dput;
        }
        ecryptfs_set_dentry_lower(dentry, lower_dentry);
        ecryptfs_set_dentry_lower_mnt(dentry, lower_mnt);
        if (!lower_dentry->d_inode) {
                /* We want to add because we couldn't find in lower */
                d_add(dentry, NULL);
                goto out;
        }
        rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb,
                                ECRYPTFS_INTERPOSE_FLAG_D_ADD);
        if (rc) {
                ecryptfs_printk(KERN_ERR, "Error interposing\n");
                goto out;
        }
        if (S_ISDIR(lower_inode->i_mode)) {
                ecryptfs_printk(KERN_DEBUG, "Is a directory; returning\n");
                goto out;
        }
        if (S_ISLNK(lower_inode->i_mode)) {
                ecryptfs_printk(KERN_DEBUG, "Is a symlink; returning\n");
                goto out;
        }
        if (special_file(lower_inode->i_mode)) {
                ecryptfs_printk(KERN_DEBUG, "Is a special file; returning\n");
                goto out;
        }
        if (!nd) {
                ecryptfs_printk(KERN_DEBUG, "We have a NULL nd, just leave"
                                "as we *think* we are about to unlink\n");
                goto out;
        }
        /* Released in this function */
        page_virt = kmem_cache_zalloc(ecryptfs_header_cache_2,
                                      GFP_USER);
        if (!page_virt) {
                rc = -ENOMEM;
                ecryptfs_printk(KERN_ERR,
                                "Cannot ecryptfs_kmalloc a page\n");
                goto out;
        }
        crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
        if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))
                ecryptfs_set_default_sizes(crypt_stat);
        if (!ecryptfs_inode_to_private(dentry->d_inode)->lower_file) {
                rc = ecryptfs_init_persistent_file(dentry);
                if (rc) {
                        printk(KERN_ERR "%s: Error attempting to initialize "
                               "the persistent file for the dentry with name "
                               "[%s]; rc = [%d]\n", __func__,
                               dentry->d_name.name, rc);
                        goto out;
                }
        }
        rc = ecryptfs_read_and_validate_header_region(page_virt,
                                                      dentry->d_inode);
        if (rc) {
                rc = ecryptfs_read_and_validate_xattr_region(page_virt, dentry);
                if (rc) {
                        printk(KERN_DEBUG "Valid metadata not found in header "
                               "region or xattr region; treating file as "
                               "unencrypted\n");
                        rc = 0;
                        kmem_cache_free(ecryptfs_header_cache_2, page_virt);
                        goto out;
                }
                crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
        }
        mount_crypt_stat = &ecryptfs_superblock_to_private(
                dentry->d_sb)->mount_crypt_stat;
        if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
                if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
                        file_size = (crypt_stat->num_header_bytes_at_front
                                     + i_size_read(lower_dentry->d_inode));
                else
                        file_size = i_size_read(lower_dentry->d_inode);
        } else {
                file_size = get_unaligned_be64(page_virt);
        }
        i_size_write(dentry->d_inode, (loff_t)file_size);
        kmem_cache_free(ecryptfs_header_cache_2, page_virt);
        goto out;

out_dput:
        dput(lower_dentry);
        d_drop(dentry);
out:
        return ERR_PTR(rc);
}

static int ecryptfs_link(struct dentry *old_dentry, struct inode *dir,
                         struct dentry *new_dentry)
{
        struct dentry *lower_old_dentry;
        struct dentry *lower_new_dentry;
        struct dentry *lower_dir_dentry;
        u64 file_size_save;
        int rc;

        file_size_save = i_size_read(old_dentry->d_inode);
        lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
        lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
        dget(lower_old_dentry);
        dget(lower_new_dentry);
        lower_dir_dentry = lock_parent(lower_new_dentry);
        rc = vfs_link(lower_old_dentry, lower_dir_dentry->d_inode,
                      lower_new_dentry);
        if (rc || !lower_new_dentry->d_inode)
                goto out_lock;
        rc = ecryptfs_interpose(lower_new_dentry, new_dentry, dir->i_sb, 0);
        if (rc)
                goto out_lock;
        fsstack_copy_attr_times(dir, lower_new_dentry->d_inode);
        fsstack_copy_inode_size(dir, lower_new_dentry->d_inode);
        old_dentry->d_inode->i_nlink =
                ecryptfs_inode_to_lower(old_dentry->d_inode)->i_nlink;
        i_size_write(new_dentry->d_inode, file_size_save);
out_lock:
        unlock_dir(lower_dir_dentry);
        dput(lower_new_dentry);
        dput(lower_old_dentry);
        d_drop(lower_old_dentry);
        d_drop(new_dentry);
        d_drop(old_dentry);
        return rc;
}

static int ecryptfs_unlink(struct inode *dir, struct dentry *dentry)
{
        int rc = 0;
        struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
        struct inode *lower_dir_inode = ecryptfs_inode_to_lower(dir);
        struct dentry *lower_dir_dentry;

        lower_dir_dentry = lock_parent(lower_dentry);
        rc = vfs_unlink(lower_dir_inode, lower_dentry);
        if (rc) {
                printk(KERN_ERR "Error in vfs_unlink; rc = [%d]\n", rc);
                goto out_unlock;
        }
        fsstack_copy_attr_times(dir, lower_dir_inode);
        dentry->d_inode->i_nlink =
                ecryptfs_inode_to_lower(dentry->d_inode)->i_nlink;
        dentry->d_inode->i_ctime = dir->i_ctime;
        d_drop(dentry);
out_unlock:
        unlock_dir(lower_dir_dentry);
        return rc;
}

static int ecryptfs_symlink(struct inode *dir, struct dentry *dentry,
                            const char *symname)
{
        int rc;
        struct dentry *lower_dentry;
        struct dentry *lower_dir_dentry;
        char *encoded_symname;
        int encoded_symlen;
        struct ecryptfs_crypt_stat *crypt_stat = NULL;

        lower_dentry = ecryptfs_dentry_to_lower(dentry);
        dget(lower_dentry);
        lower_dir_dentry = lock_parent(lower_dentry);
        encoded_symlen = ecryptfs_encode_filename(crypt_stat, symname,
                                                  strlen(symname),
                                                  &encoded_symname);
        if (encoded_symlen < 0) {
                rc = encoded_symlen;
                goto out_lock;
        }
        rc = vfs_symlink(lower_dir_dentry->d_inode, lower_dentry,
                         encoded_symname);
        kfree(encoded_symname);
        if (rc || !lower_dentry->d_inode)
                goto out_lock;
        rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
        if (rc)
                goto out_lock;
        fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
        fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
out_lock:
        unlock_dir(lower_dir_dentry);
        dput(lower_dentry);
        if (!dentry->d_inode)
                d_drop(dentry);
        return rc;
}

static int ecryptfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
        int rc;
        struct dentry *lower_dentry;
        struct dentry *lower_dir_dentry;

        lower_dentry = ecryptfs_dentry_to_lower(dentry);
        lower_dir_dentry = lock_parent(lower_dentry);
        rc = vfs_mkdir(lower_dir_dentry->d_inode, lower_dentry, mode);
        if (rc || !lower_dentry->d_inode)
                goto out;
        rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
        if (rc)
                goto out;
        fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
        fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
        dir->i_nlink = lower_dir_dentry->d_inode->i_nlink;
out:
        unlock_dir(lower_dir_dentry);
        if (!dentry->d_inode)
                d_drop(dentry);
        return rc;
}

static int ecryptfs_rmdir(struct inode *dir, struct dentry *dentry)
{
        struct dentry *lower_dentry;
        struct dentry *lower_dir_dentry;
        int rc;

        lower_dentry = ecryptfs_dentry_to_lower(dentry);
        dget(dentry);
        lower_dir_dentry = lock_parent(lower_dentry);
        dget(lower_dentry);
        rc = vfs_rmdir(lower_dir_dentry->d_inode, lower_dentry);
        dput(lower_dentry);
        if (!rc)
                d_delete(lower_dentry);
        fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
        dir->i_nlink = lower_dir_dentry->d_inode->i_nlink;
        unlock_dir(lower_dir_dentry);
        if (!rc)
                d_drop(dentry);
        dput(dentry);
        return rc;
}

static int
ecryptfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
{
        int rc;
        struct dentry *lower_dentry;
        struct dentry *lower_dir_dentry;

        lower_dentry = ecryptfs_dentry_to_lower(dentry);
        lower_dir_dentry = lock_parent(lower_dentry);
        rc = vfs_mknod(lower_dir_dentry->d_inode, lower_dentry, mode, dev);
        if (rc || !lower_dentry->d_inode)
                goto out;
        rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
        if (rc)
                goto out;
        fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
        fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
out:
        unlock_dir(lower_dir_dentry);
        if (!dentry->d_inode)
                d_drop(dentry);
        return rc;
}

static int
ecryptfs_rename(struct inode *old_dir, struct dentry *old_dentry,
                struct inode *new_dir, struct dentry *new_dentry)
{
        int rc;
        struct dentry *lower_old_dentry;
        struct dentry *lower_new_dentry;
        struct dentry *lower_old_dir_dentry;
        struct dentry *lower_new_dir_dentry;

        lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
        lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
        dget(lower_old_dentry);
        dget(lower_new_dentry);
        lower_old_dir_dentry = dget_parent(lower_old_dentry);
        lower_new_dir_dentry = dget_parent(lower_new_dentry);
        lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
        rc = vfs_rename(lower_old_dir_dentry->d_inode, lower_old_dentry,
                        lower_new_dir_dentry->d_inode, lower_new_dentry);
        if (rc)
                goto out_lock;
        fsstack_copy_attr_all(new_dir, lower_new_dir_dentry->d_inode, NULL);
        if (new_dir != old_dir)
                fsstack_copy_attr_all(old_dir, lower_old_dir_dentry->d_inode, NULL);
out_lock:
        unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
        dput(lower_new_dentry->d_parent);
        dput(lower_old_dentry->d_parent);
        dput(lower_new_dentry);
        dput(lower_old_dentry);
        return rc;
}

static int
ecryptfs_readlink(struct dentry *dentry, char __user * buf, int bufsiz)
{
        int rc;
        struct dentry *lower_dentry;
        char *decoded_name;
        char *lower_buf;
        mm_segment_t old_fs;
        struct ecryptfs_crypt_stat *crypt_stat;

        lower_dentry = ecryptfs_dentry_to_lower(dentry);
        if (!lower_dentry->d_inode->i_op ||
            !lower_dentry->d_inode->i_op->readlink) {
                rc = -EINVAL;
                goto out;
        }
        /* Released in this function */
        lower_buf = kmalloc(bufsiz, GFP_KERNEL);
        if (lower_buf == NULL) {
                ecryptfs_printk(KERN_ERR, "Out of memory\n");
                rc = -ENOMEM;
                goto out;
        }
        old_fs = get_fs();
        set_fs(get_ds());
        ecryptfs_printk(KERN_DEBUG, "Calling readlink w/ "
                        "lower_dentry->d_name.name = [%s]\n",
                        lower_dentry->d_name.name);
        rc = lower_dentry->d_inode->i_op->readlink(lower_dentry,
                                                   (char __user *)lower_buf,
                                                   bufsiz);
        set_fs(old_fs);
        if (rc >= 0) {
                crypt_stat = NULL;
                rc = ecryptfs_decode_filename(crypt_stat, lower_buf, rc,
                                              &decoded_name);
                if (rc == -ENOMEM)
                        goto out_free_lower_buf;
                if (rc > 0) {
                        ecryptfs_printk(KERN_DEBUG, "Copying [%d] bytes "
                                        "to userspace: [%*s]\n", rc,
                                        decoded_name);
                        if (copy_to_user(buf, decoded_name, rc))
                                rc = -EFAULT;
                }
                kfree(decoded_name);
                fsstack_copy_attr_atime(dentry->d_inode,
                                        lower_dentry->d_inode);
        }
out_free_lower_buf:
        kfree(lower_buf);
out:
        return rc;
}

static void *ecryptfs_follow_link(struct dentry *dentry, struct nameidata *nd)
{
        char *buf;
        int len = PAGE_SIZE, rc;
        mm_segment_t old_fs;

        /* Released in ecryptfs_put_link(); only release here on error */
        buf = kmalloc(len, GFP_KERNEL);
        if (!buf) {
                rc = -ENOMEM;
                goto out;
        }
        old_fs = get_fs();
        set_fs(get_ds());
        ecryptfs_printk(KERN_DEBUG, "Calling readlink w/ "
                        "dentry->d_name.name = [%s]\n", dentry->d_name.name);
        rc = dentry->d_inode->i_op->readlink(dentry, (char __user *)buf, len);
        buf[rc] = '\0';
        set_fs(old_fs);
        if (rc < 0)
                goto out_free;
        rc = 0;
        nd_set_link(nd, buf);
        goto out;
out_free:
        kfree(buf);
out:
        return ERR_PTR(rc);
}

static void
ecryptfs_put_link(struct dentry *dentry, struct nameidata *nd, void *ptr)
{
        /* Free the char* */
        kfree(nd_get_link(nd));
}

/**
 * upper_size_to_lower_size
 * @crypt_stat: Crypt_stat associated with file
 * @upper_size: Size of the upper file
 *
 * Calculate the required size of the lower file based on the
 * specified size of the upper file. This calculation is based on the
 * number of headers in the underlying file and the extent size.
 *
 * Returns Calculated size of the lower file.
 */
static loff_t
upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
                         loff_t upper_size)
{
        loff_t lower_size;

        lower_size = crypt_stat->num_header_bytes_at_front;
        if (upper_size != 0) {
                loff_t num_extents;

                num_extents = upper_size >> crypt_stat->extent_shift;
                if (upper_size & ~crypt_stat->extent_mask)
                        num_extents++;
                lower_size += (num_extents * crypt_stat->extent_size);
        }
        return lower_size;
}

/**
 * ecryptfs_truncate
 * @dentry: The ecryptfs layer dentry
 * @new_length: The length to expand the file to
 *
 * Function to handle truncations modifying the size of the file. Note
 * that the file sizes are interpolated. When expanding, we are simply
 * writing strings of 0's out. When truncating, we need to modify the
 * underlying file size according to the page index interpolations.
 *
 * Returns zero on success; non-zero otherwise
 */
int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
{
        int rc = 0;
        struct inode *inode = dentry->d_inode;
        struct dentry *lower_dentry;
        struct file fake_ecryptfs_file;
        struct ecryptfs_crypt_stat *crypt_stat;
        loff_t i_size = i_size_read(inode);
        loff_t lower_size_before_truncate;
        loff_t lower_size_after_truncate;

        if (unlikely((new_length == i_size)))
                goto out;
        crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
        /* Set up a fake ecryptfs file, this is used to interface with
         * the file in the underlying filesystem so that the
         * truncation has an effect there as well. */
        memset(&fake_ecryptfs_file, 0, sizeof(fake_ecryptfs_file));
        fake_ecryptfs_file.f_path.dentry = dentry;
        /* Released at out_free: label */
        ecryptfs_set_file_private(&fake_ecryptfs_file,
                                  kmem_cache_alloc(ecryptfs_file_info_cache,
                                                   GFP_KERNEL));
        if (unlikely(!ecryptfs_file_to_private(&fake_ecryptfs_file))) {
                rc = -ENOMEM;
                goto out;
        }
        lower_dentry = ecryptfs_dentry_to_lower(dentry);
        ecryptfs_set_file_lower(
                &fake_ecryptfs_file,
                ecryptfs_inode_to_private(dentry->d_inode)->lower_file);
        /* Switch on growing or shrinking file */
        if (new_length > i_size) {
                char zero[] = { 0x00 };

                /* Write a single 0 at the last position of the file;
                 * this triggers code that will fill in 0's throughout
                 * the intermediate portion of the previous end of the
                 * file and the new and of the file */
                rc = ecryptfs_write(&fake_ecryptfs_file, zero,
                                    (new_length - 1), 1);
        } else { /* new_length < i_size_read(inode) */
                /* We're chopping off all the pages down do the page
                 * in which new_length is located. Fill in the end of
                 * that page from (new_length & ~PAGE_CACHE_MASK) to
                 * PAGE_CACHE_SIZE with zeros. */
                size_t num_zeros = (PAGE_CACHE_SIZE
                                    - (new_length & ~PAGE_CACHE_MASK));

                if (num_zeros) {
                        char *zeros_virt;

                        zeros_virt = kzalloc(num_zeros, GFP_KERNEL);
                        if (!zeros_virt) {
                                rc = -ENOMEM;
                                goto out_free;
                        }
                        rc = ecryptfs_write(&fake_ecryptfs_file, zeros_virt,
                                            new_length, num_zeros);
                        kfree(zeros_virt);
                        if (rc) {
                                printk(KERN_ERR "Error attempting to zero out "
                                       "the remainder of the end page on "
                                       "reducing truncate; rc = [%d]\n", rc);
                                goto out_free;
                        }
                }
                vmtruncate(inode, new_length);
                rc = ecryptfs_write_inode_size_to_metadata(inode);
                if (rc) {
                        printk(KERN_ERR "Problem with "
                               "ecryptfs_write_inode_size_to_metadata; "
                               "rc = [%d]\n", rc);
                        goto out_free;
                }
                /* We are reducing the size of the ecryptfs file, and need to
                 * know if we need to reduce the size of the lower file. */
                lower_size_before_truncate =
                    upper_size_to_lower_size(crypt_stat, i_size);
                lower_size_after_truncate =
                    upper_size_to_lower_size(crypt_stat, new_length);
                if (lower_size_after_truncate < lower_size_before_truncate)
                        vmtruncate(lower_dentry->d_inode,
                                   lower_size_after_truncate);
        }
out_free:
        if (ecryptfs_file_to_private(&fake_ecryptfs_file))
                kmem_cache_free(ecryptfs_file_info_cache,
                                ecryptfs_file_to_private(&fake_ecryptfs_file));
out:
        return rc;
}

static int
ecryptfs_permission(struct inode *inode, int mask)
{
        return inode_permission(ecryptfs_inode_to_lower(inode), mask);
}

/**
 * ecryptfs_setattr
 * @dentry: dentry handle to the inode to modify
 * @ia: Structure with flags of what to change and values
 *
 * Updates the metadata of an inode. If the update is to the size
 * i.e. truncation, then ecryptfs_truncate will handle the size modification
 * of both the ecryptfs inode and the lower inode.
 *
 * All other metadata changes will be passed right to the lower filesystem,
 * and we will just update our inode to look like the lower.
 */
static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
{
        int rc = 0;
        struct dentry *lower_dentry;
        struct inode *inode;
        struct inode *lower_inode;
        struct ecryptfs_crypt_stat *crypt_stat;

        crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
        if (!(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED))
                ecryptfs_init_crypt_stat(crypt_stat);
        inode = dentry->d_inode;
        lower_inode = ecryptfs_inode_to_lower(inode);
        lower_dentry = ecryptfs_dentry_to_lower(dentry);
        mutex_lock(&crypt_stat->cs_mutex);
        if (S_ISDIR(dentry->d_inode->i_mode))
                crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
        else if (S_ISREG(dentry->d_inode->i_mode)
                 && (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
                     || !(crypt_stat->flags & ECRYPTFS_KEY_VALID))) {
                struct ecryptfs_mount_crypt_stat *mount_crypt_stat;

                mount_crypt_stat = &ecryptfs_superblock_to_private(
                        dentry->d_sb)->mount_crypt_stat;
                rc = ecryptfs_read_metadata(dentry);
                if (rc) {
                        if (!(mount_crypt_stat->flags
                              & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
                                rc = -EIO;
                                printk(KERN_WARNING "Either the lower file "
                                       "is not in a valid eCryptfs format, "
                                       "or the key could not be retrieved. "
                                       "Plaintext passthrough mode is not "
                                       "enabled; returning -EIO\n");
                                mutex_unlock(&crypt_stat->cs_mutex);
                                goto out;
                        }
                        rc = 0;
                        crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
                        mutex_unlock(&crypt_stat->cs_mutex);
                        goto out;
                }
        }
        mutex_unlock(&crypt_stat->cs_mutex);
        if (ia->ia_valid & ATTR_SIZE) {
                ecryptfs_printk(KERN_DEBUG,
                                "ia->ia_valid = [0x%x] ATTR_SIZE" " = [0x%x]\n",
                                ia->ia_valid, ATTR_SIZE);
                rc = ecryptfs_truncate(dentry, ia->ia_size);
                /* ecryptfs_truncate handles resizing of the lower file */
                ia->ia_valid &= ~ATTR_SIZE;
                ecryptfs_printk(KERN_DEBUG, "ia->ia_valid = [%x]\n",
                                ia->ia_valid);
                if (rc < 0)
                        goto out;
        }

        /*
         * mode change is for clearing setuid/setgid bits. Allow lower fs
         * to interpret this in its own way.
         */
        if (ia->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
                ia->ia_valid &= ~ATTR_MODE;

        mutex_lock(&lower_dentry->d_inode->i_mutex);
        rc = notify_change(lower_dentry, ia);
        mutex_unlock(&lower_dentry->d_inode->i_mutex);
out:
        fsstack_copy_attr_all(inode, lower_inode, NULL);
        return rc;
}

int
ecryptfs_setxattr(struct dentry *dentry, const char *name, const void *value,
                  size_t size, int flags)
{
        int rc = 0;
        struct dentry *lower_dentry;

        lower_dentry = ecryptfs_dentry_to_lower(dentry);
        if (!lower_dentry->d_inode->i_op->setxattr) {
                rc = -ENOSYS;
                goto out;
        }
        mutex_lock(&lower_dentry->d_inode->i_mutex);
        rc = lower_dentry->d_inode->i_op->setxattr(lower_dentry, name, value,
                                                   size, flags);
        mutex_unlock(&lower_dentry->d_inode->i_mutex);
out:
        return rc;
}

ssize_t
ecryptfs_getxattr_lower(struct dentry *lower_dentry, const char *name,
                        void *value, size_t size)
{
        int rc = 0;

        if (!lower_dentry->d_inode->i_op->getxattr) {
                rc = -ENOSYS;
                goto out;
        }
        mutex_lock(&lower_dentry->d_inode->i_mutex);
        rc = lower_dentry->d_inode->i_op->getxattr(lower_dentry, name, value,
                                                   size);
        mutex_unlock(&lower_dentry->d_inode->i_mutex);
out:
        return rc;
}

static ssize_t
ecryptfs_getxattr(struct dentry *dentry, const char *name, void *value,
                  size_t size)
{
        return ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry), name,
                                       value, size);
}

static ssize_t
ecryptfs_listxattr(struct dentry *dentry, char *list, size_t size)
{
        int rc = 0;
        struct dentry *lower_dentry;

        lower_dentry = ecryptfs_dentry_to_lower(dentry);
        if (!lower_dentry->d_inode->i_op->listxattr) {
                rc = -ENOSYS;
                goto out;
        }
        mutex_lock(&lower_dentry->d_inode->i_mutex);
        rc = lower_dentry->d_inode->i_op->listxattr(lower_dentry, list, size);
        mutex_unlock(&lower_dentry->d_inode->i_mutex);
out:
        return rc;
}

static int ecryptfs_removexattr(struct dentry *dentry, const char *name)
{
        int rc = 0;
        struct dentry *lower_dentry;

        lower_dentry = ecryptfs_dentry_to_lower(dentry);
        if (!lower_dentry->d_inode->i_op->removexattr) {
                rc = -ENOSYS;
                goto out;
        }
        mutex_lock(&lower_dentry->d_inode->i_mutex);
        rc = lower_dentry->d_inode->i_op->removexattr(lower_dentry, name);
        mutex_unlock(&lower_dentry->d_inode->i_mutex);
out:
        return rc;
}

int ecryptfs_inode_test(struct inode *inode, void *candidate_lower_inode)
{
        if ((ecryptfs_inode_to_lower(inode)
             == (struct inode *)candidate_lower_inode))
                return 1;
        else
                return 0;
}

int ecryptfs_inode_set(struct inode *inode, void *lower_inode)
{
        ecryptfs_init_inode(inode, (struct inode *)lower_inode);
        return 0;
}

const struct inode_operations ecryptfs_symlink_iops = {
        .readlink = ecryptfs_readlink,
        .follow_link = ecryptfs_follow_link,
        .put_link = ecryptfs_put_link,
        .permission = ecryptfs_permission,
        .setattr = ecryptfs_setattr,
        .setxattr = ecryptfs_setxattr,
        .getxattr = ecryptfs_getxattr,
        .listxattr = ecryptfs_listxattr,
        .removexattr = ecryptfs_removexattr
};

const struct inode_operations ecryptfs_dir_iops = {
        .create = ecryptfs_create,
        .lookup = ecryptfs_lookup,
        .link = ecryptfs_link,
        .unlink = ecryptfs_unlink,
        .symlink = ecryptfs_symlink,
        .mkdir = ecryptfs_mkdir,
        .rmdir = ecryptfs_rmdir,
        .mknod = ecryptfs_mknod,
        .rename = ecryptfs_rename,
        .permission = ecryptfs_permission,
        .setattr = ecryptfs_setattr,
        .setxattr = ecryptfs_setxattr,
        .getxattr = ecryptfs_getxattr,
        .listxattr = ecryptfs_listxattr,
        .removexattr = ecryptfs_removexattr
};

const struct inode_operations ecryptfs_main_iops = {
        .permission = ecryptfs_permission,
        .setattr = ecryptfs_setattr,
        .setxattr = ecryptfs_setxattr,
        .getxattr = ecryptfs_getxattr,
        .listxattr = ecryptfs_listxattr,
        .removexattr = ecryptfs_removexattr
};