linux-imx

/**

 * eCryptfs: Linux filesystem encryption layer

 *

 * Copyright (C) 2004-2008 International Business Machines Corp.

 *   Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>

 *      Tyler Hicks <tyhicks@ou.edu>

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License version

 * 2 as published by the Free Software Foundation.

 *

 * 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/sched.h>

#include <linux/slab.h>

#include <linux/user_namespace.h>

#include <linux/nsproxy.h>

#include "ecryptfs_kernel.h"

​

static LIST_HEAD(ecryptfs_msg_ctx_free_list);

static LIST_HEAD(ecryptfs_msg_ctx_alloc_list);

static struct mutex ecryptfs_msg_ctx_lists_mux;

​

static struct hlist_head *ecryptfs_daemon_hash;

struct mutex ecryptfs_daemon_hash_mux;

static int ecryptfs_hash_bits;

#define ecryptfs_current_euid_hash(uid) \

    hash_long((unsigned long)from_kuid(&init_user_ns, current_euid()), ecryptfs_hash_bits)

​

static u32 ecryptfs_msg_counter;

static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;

​

/**

 * ecryptfs_acquire_free_msg_ctx

 * @msg_ctx: The context that was acquired from the free list

 *

 * Acquires a context element from the free list and locks the mutex

 * on the context.  Sets the msg_ctx task to current.  Returns zero on

 * success; non-zero on error or upon failure to acquire a free

 * context element.  Must be called with ecryptfs_msg_ctx_lists_mux

 * held.

 */

static int ecryptfs_acquire_free_msg_ctx(struct ecryptfs_msg_ctx **msg_ctx)

{

    struct list_head *p;

    int rc;

​

    if (list_empty(&ecryptfs_msg_ctx_free_list)) {

        printk(KERN_WARNING "%s: The eCryptfs free "

               "context list is empty.  It may be helpful to "

               "specify the ecryptfs_message_buf_len "

               "parameter to be greater than the current "

               "value of [%d]\n", __func__, ecryptfs_message_buf_len);

        rc = -ENOMEM;

        goto out;

    }

    list_for_each(p, &ecryptfs_msg_ctx_free_list) {

        *msg_ctx = list_entry(p, struct ecryptfs_msg_ctx, node);

        if (mutex_trylock(&(*msg_ctx)->mux)) {

            (*msg_ctx)->task = current;

            rc = 0;

            goto out;

        }

    }

    rc = -ENOMEM;

out:

    return rc;

}

​

/**

 * ecryptfs_msg_ctx_free_to_alloc

 * @msg_ctx: The context to move from the free list to the alloc list

 *

 * Must be called with ecryptfs_msg_ctx_lists_mux held.

 */

static void ecryptfs_msg_ctx_free_to_alloc(struct ecryptfs_msg_ctx *msg_ctx)

{

    list_move(&msg_ctx->node, &ecryptfs_msg_ctx_alloc_list);

    msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_PENDING;

    msg_ctx->counter = ++ecryptfs_msg_counter;

}

​

/**

 * ecryptfs_msg_ctx_alloc_to_free