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![Fabian Frederick](/assets/img/avatar_default.png)
Fix checkpatch warning: WARNING: kfree(NULL) is safe this check is probably not required Signed-off-by: Fabian Frederick <fabf@skynet.be> Cc: ecryptfs@vger.kernel.org Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
468 lines
14 KiB
C
468 lines
14 KiB
C
/**
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* eCryptfs: Linux filesystem encryption layer
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*
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* Copyright (C) 2004-2008 International Business Machines Corp.
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* Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
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* Tyler Hicks <tyhicks@ou.edu>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version
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* 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
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* 02111-1307, USA.
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*/
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/user_namespace.h>
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#include <linux/nsproxy.h>
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#include "ecryptfs_kernel.h"
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static LIST_HEAD(ecryptfs_msg_ctx_free_list);
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static LIST_HEAD(ecryptfs_msg_ctx_alloc_list);
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static struct mutex ecryptfs_msg_ctx_lists_mux;
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static struct hlist_head *ecryptfs_daemon_hash;
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struct mutex ecryptfs_daemon_hash_mux;
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static int ecryptfs_hash_bits;
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#define ecryptfs_current_euid_hash(uid) \
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hash_long((unsigned long)from_kuid(&init_user_ns, current_euid()), ecryptfs_hash_bits)
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static u32 ecryptfs_msg_counter;
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static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;
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/**
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* ecryptfs_acquire_free_msg_ctx
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* @msg_ctx: The context that was acquired from the free list
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*
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* Acquires a context element from the free list and locks the mutex
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* on the context. Sets the msg_ctx task to current. Returns zero on
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* success; non-zero on error or upon failure to acquire a free
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* context element. Must be called with ecryptfs_msg_ctx_lists_mux
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* held.
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*/
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static int ecryptfs_acquire_free_msg_ctx(struct ecryptfs_msg_ctx **msg_ctx)
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{
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struct list_head *p;
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int rc;
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if (list_empty(&ecryptfs_msg_ctx_free_list)) {
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printk(KERN_WARNING "%s: The eCryptfs free "
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"context list is empty. It may be helpful to "
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"specify the ecryptfs_message_buf_len "
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"parameter to be greater than the current "
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"value of [%d]\n", __func__, ecryptfs_message_buf_len);
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rc = -ENOMEM;
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goto out;
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}
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list_for_each(p, &ecryptfs_msg_ctx_free_list) {
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*msg_ctx = list_entry(p, struct ecryptfs_msg_ctx, node);
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if (mutex_trylock(&(*msg_ctx)->mux)) {
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(*msg_ctx)->task = current;
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rc = 0;
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goto out;
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}
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}
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rc = -ENOMEM;
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out:
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return rc;
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}
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/**
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* ecryptfs_msg_ctx_free_to_alloc
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* @msg_ctx: The context to move from the free list to the alloc list
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*
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* Must be called with ecryptfs_msg_ctx_lists_mux held.
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*/
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static void ecryptfs_msg_ctx_free_to_alloc(struct ecryptfs_msg_ctx *msg_ctx)
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{
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list_move(&msg_ctx->node, &ecryptfs_msg_ctx_alloc_list);
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msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_PENDING;
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msg_ctx->counter = ++ecryptfs_msg_counter;
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}
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/**
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* ecryptfs_msg_ctx_alloc_to_free
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* @msg_ctx: The context to move from the alloc list to the free list
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*
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* Must be called with ecryptfs_msg_ctx_lists_mux held.
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*/
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void ecryptfs_msg_ctx_alloc_to_free(struct ecryptfs_msg_ctx *msg_ctx)
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{
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list_move(&(msg_ctx->node), &ecryptfs_msg_ctx_free_list);
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kfree(msg_ctx->msg);
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msg_ctx->msg = NULL;
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msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_FREE;
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}
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/**
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* ecryptfs_find_daemon_by_euid
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* @daemon: If return value is zero, points to the desired daemon pointer
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*
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* Must be called with ecryptfs_daemon_hash_mux held.
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*
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* Search the hash list for the current effective user id.
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*
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* Returns zero if the user id exists in the list; non-zero otherwise.
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*/
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int ecryptfs_find_daemon_by_euid(struct ecryptfs_daemon **daemon)
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{
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int rc;
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hlist_for_each_entry(*daemon,
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&ecryptfs_daemon_hash[ecryptfs_current_euid_hash()],
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euid_chain) {
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if (uid_eq((*daemon)->file->f_cred->euid, current_euid())) {
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rc = 0;
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goto out;
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}
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}
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rc = -EINVAL;
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out:
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return rc;
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}
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/**
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* ecryptfs_spawn_daemon - Create and initialize a new daemon struct
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* @daemon: Pointer to set to newly allocated daemon struct
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* @file: File used when opening /dev/ecryptfs
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*
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* Must be called ceremoniously while in possession of
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* ecryptfs_sacred_daemon_hash_mux
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*
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* Returns zero on success; non-zero otherwise
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*/
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int
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ecryptfs_spawn_daemon(struct ecryptfs_daemon **daemon, struct file *file)
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{
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int rc = 0;
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(*daemon) = kzalloc(sizeof(**daemon), GFP_KERNEL);
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if (!(*daemon)) {
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rc = -ENOMEM;
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printk(KERN_ERR "%s: Failed to allocate [%zd] bytes of "
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"GFP_KERNEL memory\n", __func__, sizeof(**daemon));
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goto out;
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}
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(*daemon)->file = file;
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mutex_init(&(*daemon)->mux);
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INIT_LIST_HEAD(&(*daemon)->msg_ctx_out_queue);
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init_waitqueue_head(&(*daemon)->wait);
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(*daemon)->num_queued_msg_ctx = 0;
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hlist_add_head(&(*daemon)->euid_chain,
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&ecryptfs_daemon_hash[ecryptfs_current_euid_hash()]);
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out:
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return rc;
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}
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/**
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* ecryptfs_exorcise_daemon - Destroy the daemon struct
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*
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* Must be called ceremoniously while in possession of
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* ecryptfs_daemon_hash_mux and the daemon's own mux.
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*/
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int ecryptfs_exorcise_daemon(struct ecryptfs_daemon *daemon)
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{
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struct ecryptfs_msg_ctx *msg_ctx, *msg_ctx_tmp;
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int rc = 0;
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mutex_lock(&daemon->mux);
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if ((daemon->flags & ECRYPTFS_DAEMON_IN_READ)
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|| (daemon->flags & ECRYPTFS_DAEMON_IN_POLL)) {
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rc = -EBUSY;
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mutex_unlock(&daemon->mux);
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goto out;
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}
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list_for_each_entry_safe(msg_ctx, msg_ctx_tmp,
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&daemon->msg_ctx_out_queue, daemon_out_list) {
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list_del(&msg_ctx->daemon_out_list);
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daemon->num_queued_msg_ctx--;
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printk(KERN_WARNING "%s: Warning: dropping message that is in "
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"the out queue of a dying daemon\n", __func__);
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ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
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}
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hlist_del(&daemon->euid_chain);
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mutex_unlock(&daemon->mux);
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kzfree(daemon);
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out:
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return rc;
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}
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/**
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* ecryptfs_process_reponse
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* @msg: The ecryptfs message received; the caller should sanity check
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* msg->data_len and free the memory
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* @seq: The sequence number of the message; must match the sequence
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* number for the existing message context waiting for this
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* response
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*
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* Processes a response message after sending an operation request to
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* userspace. Some other process is awaiting this response. Before
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* sending out its first communications, the other process allocated a
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* msg_ctx from the ecryptfs_msg_ctx_arr at a particular index. The
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* response message contains this index so that we can copy over the
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* response message into the msg_ctx that the process holds a
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* reference to. The other process is going to wake up, check to see
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* that msg_ctx->state == ECRYPTFS_MSG_CTX_STATE_DONE, and then
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* proceed to read off and process the response message. Returns zero
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* upon delivery to desired context element; non-zero upon delivery
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* failure or error.
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*
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* Returns zero on success; non-zero otherwise
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*/
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int ecryptfs_process_response(struct ecryptfs_daemon *daemon,
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struct ecryptfs_message *msg, u32 seq)
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{
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struct ecryptfs_msg_ctx *msg_ctx;
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size_t msg_size;
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int rc;
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if (msg->index >= ecryptfs_message_buf_len) {
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rc = -EINVAL;
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printk(KERN_ERR "%s: Attempt to reference "
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"context buffer at index [%d]; maximum "
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"allowable is [%d]\n", __func__, msg->index,
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(ecryptfs_message_buf_len - 1));
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goto out;
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}
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msg_ctx = &ecryptfs_msg_ctx_arr[msg->index];
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mutex_lock(&msg_ctx->mux);
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if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_PENDING) {
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rc = -EINVAL;
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printk(KERN_WARNING "%s: Desired context element is not "
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"pending a response\n", __func__);
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goto unlock;
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} else if (msg_ctx->counter != seq) {
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rc = -EINVAL;
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printk(KERN_WARNING "%s: Invalid message sequence; "
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"expected [%d]; received [%d]\n", __func__,
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msg_ctx->counter, seq);
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goto unlock;
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}
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msg_size = (sizeof(*msg) + msg->data_len);
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msg_ctx->msg = kmemdup(msg, msg_size, GFP_KERNEL);
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if (!msg_ctx->msg) {
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rc = -ENOMEM;
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printk(KERN_ERR "%s: Failed to allocate [%zd] bytes of "
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"GFP_KERNEL memory\n", __func__, msg_size);
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goto unlock;
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}
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msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_DONE;
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wake_up_process(msg_ctx->task);
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rc = 0;
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unlock:
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mutex_unlock(&msg_ctx->mux);
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out:
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return rc;
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}
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/**
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* ecryptfs_send_message_locked
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* @data: The data to send
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* @data_len: The length of data
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* @msg_ctx: The message context allocated for the send
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*
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* Must be called with ecryptfs_daemon_hash_mux held.
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*
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* Returns zero on success; non-zero otherwise
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*/
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static int
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ecryptfs_send_message_locked(char *data, int data_len, u8 msg_type,
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struct ecryptfs_msg_ctx **msg_ctx)
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{
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struct ecryptfs_daemon *daemon;
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int rc;
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rc = ecryptfs_find_daemon_by_euid(&daemon);
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if (rc) {
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rc = -ENOTCONN;
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goto out;
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}
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mutex_lock(&ecryptfs_msg_ctx_lists_mux);
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rc = ecryptfs_acquire_free_msg_ctx(msg_ctx);
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if (rc) {
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mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
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printk(KERN_WARNING "%s: Could not claim a free "
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"context element\n", __func__);
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goto out;
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}
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ecryptfs_msg_ctx_free_to_alloc(*msg_ctx);
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mutex_unlock(&(*msg_ctx)->mux);
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mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
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rc = ecryptfs_send_miscdev(data, data_len, *msg_ctx, msg_type, 0,
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daemon);
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if (rc)
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printk(KERN_ERR "%s: Error attempting to send message to "
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"userspace daemon; rc = [%d]\n", __func__, rc);
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out:
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return rc;
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}
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/**
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* ecryptfs_send_message
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* @data: The data to send
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* @data_len: The length of data
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* @msg_ctx: The message context allocated for the send
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*
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* Grabs ecryptfs_daemon_hash_mux.
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*
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* Returns zero on success; non-zero otherwise
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*/
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int ecryptfs_send_message(char *data, int data_len,
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struct ecryptfs_msg_ctx **msg_ctx)
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{
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int rc;
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mutex_lock(&ecryptfs_daemon_hash_mux);
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rc = ecryptfs_send_message_locked(data, data_len, ECRYPTFS_MSG_REQUEST,
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msg_ctx);
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mutex_unlock(&ecryptfs_daemon_hash_mux);
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return rc;
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}
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/**
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* ecryptfs_wait_for_response
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* @msg_ctx: The context that was assigned when sending a message
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* @msg: The incoming message from userspace; not set if rc != 0
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*
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* Sleeps until awaken by ecryptfs_receive_message or until the amount
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* of time exceeds ecryptfs_message_wait_timeout. If zero is
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* returned, msg will point to a valid message from userspace; a
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* non-zero value is returned upon failure to receive a message or an
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* error occurs. Callee must free @msg on success.
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*/
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int ecryptfs_wait_for_response(struct ecryptfs_msg_ctx *msg_ctx,
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struct ecryptfs_message **msg)
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{
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signed long timeout = ecryptfs_message_wait_timeout * HZ;
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int rc = 0;
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sleep:
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timeout = schedule_timeout_interruptible(timeout);
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mutex_lock(&ecryptfs_msg_ctx_lists_mux);
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mutex_lock(&msg_ctx->mux);
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if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_DONE) {
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if (timeout) {
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mutex_unlock(&msg_ctx->mux);
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mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
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goto sleep;
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}
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rc = -ENOMSG;
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} else {
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*msg = msg_ctx->msg;
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msg_ctx->msg = NULL;
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}
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ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
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mutex_unlock(&msg_ctx->mux);
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mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
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return rc;
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}
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int __init ecryptfs_init_messaging(void)
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{
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int i;
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int rc = 0;
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if (ecryptfs_number_of_users > ECRYPTFS_MAX_NUM_USERS) {
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ecryptfs_number_of_users = ECRYPTFS_MAX_NUM_USERS;
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printk(KERN_WARNING "%s: Specified number of users is "
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"too large, defaulting to [%d] users\n", __func__,
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ecryptfs_number_of_users);
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}
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mutex_init(&ecryptfs_daemon_hash_mux);
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mutex_lock(&ecryptfs_daemon_hash_mux);
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ecryptfs_hash_bits = 1;
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while (ecryptfs_number_of_users >> ecryptfs_hash_bits)
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ecryptfs_hash_bits++;
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ecryptfs_daemon_hash = kmalloc((sizeof(struct hlist_head)
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* (1 << ecryptfs_hash_bits)),
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GFP_KERNEL);
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if (!ecryptfs_daemon_hash) {
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rc = -ENOMEM;
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printk(KERN_ERR "%s: Failed to allocate memory\n", __func__);
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mutex_unlock(&ecryptfs_daemon_hash_mux);
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goto out;
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}
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for (i = 0; i < (1 << ecryptfs_hash_bits); i++)
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INIT_HLIST_HEAD(&ecryptfs_daemon_hash[i]);
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mutex_unlock(&ecryptfs_daemon_hash_mux);
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ecryptfs_msg_ctx_arr = kmalloc((sizeof(struct ecryptfs_msg_ctx)
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* ecryptfs_message_buf_len),
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GFP_KERNEL);
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if (!ecryptfs_msg_ctx_arr) {
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rc = -ENOMEM;
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printk(KERN_ERR "%s: Failed to allocate memory\n", __func__);
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goto out;
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}
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mutex_init(&ecryptfs_msg_ctx_lists_mux);
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mutex_lock(&ecryptfs_msg_ctx_lists_mux);
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ecryptfs_msg_counter = 0;
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for (i = 0; i < ecryptfs_message_buf_len; i++) {
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INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].node);
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INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].daemon_out_list);
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mutex_init(&ecryptfs_msg_ctx_arr[i].mux);
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mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
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ecryptfs_msg_ctx_arr[i].index = i;
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ecryptfs_msg_ctx_arr[i].state = ECRYPTFS_MSG_CTX_STATE_FREE;
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ecryptfs_msg_ctx_arr[i].counter = 0;
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ecryptfs_msg_ctx_arr[i].task = NULL;
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ecryptfs_msg_ctx_arr[i].msg = NULL;
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list_add_tail(&ecryptfs_msg_ctx_arr[i].node,
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&ecryptfs_msg_ctx_free_list);
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mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
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}
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mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
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rc = ecryptfs_init_ecryptfs_miscdev();
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if (rc)
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ecryptfs_release_messaging();
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out:
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return rc;
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}
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void ecryptfs_release_messaging(void)
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{
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if (ecryptfs_msg_ctx_arr) {
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int i;
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mutex_lock(&ecryptfs_msg_ctx_lists_mux);
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for (i = 0; i < ecryptfs_message_buf_len; i++) {
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mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
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kfree(ecryptfs_msg_ctx_arr[i].msg);
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mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
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}
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kfree(ecryptfs_msg_ctx_arr);
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mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
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}
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if (ecryptfs_daemon_hash) {
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struct ecryptfs_daemon *daemon;
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int i;
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mutex_lock(&ecryptfs_daemon_hash_mux);
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for (i = 0; i < (1 << ecryptfs_hash_bits); i++) {
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int rc;
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hlist_for_each_entry(daemon,
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&ecryptfs_daemon_hash[i],
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euid_chain) {
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rc = ecryptfs_exorcise_daemon(daemon);
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if (rc)
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printk(KERN_ERR "%s: Error whilst "
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"attempting to destroy daemon; "
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|
"rc = [%d]. Dazed and confused, "
|
|
"but trying to continue.\n",
|
|
__func__, rc);
|
|
}
|
|
}
|
|
kfree(ecryptfs_daemon_hash);
|
|
mutex_unlock(&ecryptfs_daemon_hash_mux);
|
|
}
|
|
ecryptfs_destroy_ecryptfs_miscdev();
|
|
return;
|
|
}
|