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yaml --- r: 105447 b: refs/heads/master c: 746f1e5 h: refs/heads/master i: 105445: ab19eb6 105443: 9be5476 105439: ddfdb8e v: v3
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Michael Halcrow
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Linus Torvalds
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Jul 24, 2008
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| Original file line number | Diff line number | Diff line change |
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| @@ -1,2 +1,2 @@ | ||
| --- | ||
| refs/heads/master: 0293902a4d66fab27d0ddcc0766e05dae68f004e | ||
| refs/heads/master: 746f1e558bc52b9693c1a1ecdab60f8392e5ff18 |
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| Original file line number | Diff line number | Diff line change |
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| /** | ||
| * eCryptfs: Linux filesystem encryption layer | ||
| * | ||
| * Copyright (C) 2008 International Business Machines Corp. | ||
| * Author(s): Michael A. Halcrow <mahalcro@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/kthread.h> | ||
| #include <linux/freezer.h> | ||
| #include <linux/wait.h> | ||
| #include <linux/mount.h> | ||
| #include "ecryptfs_kernel.h" | ||
|
|
||
| struct kmem_cache *ecryptfs_open_req_cache; | ||
|
|
||
| static struct ecryptfs_kthread_ctl { | ||
| #define ECRYPTFS_KTHREAD_ZOMBIE 0x00000001 | ||
| u32 flags; | ||
| struct mutex mux; | ||
| struct list_head req_list; | ||
| wait_queue_head_t wait; | ||
| } ecryptfs_kthread_ctl; | ||
|
|
||
| static struct task_struct *ecryptfs_kthread; | ||
|
|
||
| /** | ||
| * ecryptfs_threadfn | ||
| * @ignored: ignored | ||
| * | ||
| * The eCryptfs kernel thread that has the responsibility of getting | ||
| * the lower persistent file with RW permissions. | ||
| * | ||
| * Returns zero on success; non-zero otherwise | ||
| */ | ||
| static int ecryptfs_threadfn(void *ignored) | ||
| { | ||
| set_freezable(); | ||
| while (1) { | ||
| struct ecryptfs_open_req *req; | ||
|
|
||
| wait_event_freezable( | ||
| ecryptfs_kthread_ctl.wait, | ||
| (!list_empty(&ecryptfs_kthread_ctl.req_list) | ||
| || kthread_should_stop())); | ||
| mutex_lock(&ecryptfs_kthread_ctl.mux); | ||
| if (ecryptfs_kthread_ctl.flags & ECRYPTFS_KTHREAD_ZOMBIE) { | ||
| mutex_unlock(&ecryptfs_kthread_ctl.mux); | ||
| goto out; | ||
| } | ||
| while (!list_empty(&ecryptfs_kthread_ctl.req_list)) { | ||
| req = list_first_entry(&ecryptfs_kthread_ctl.req_list, | ||
| struct ecryptfs_open_req, | ||
| kthread_ctl_list); | ||
| mutex_lock(&req->mux); | ||
| list_del(&req->kthread_ctl_list); | ||
| if (!(req->flags & ECRYPTFS_REQ_ZOMBIE)) { | ||
| dget(req->lower_dentry); | ||
| mntget(req->lower_mnt); | ||
| (*req->lower_file) = dentry_open( | ||
| req->lower_dentry, req->lower_mnt, | ||
| (O_RDWR | O_LARGEFILE)); | ||
| req->flags |= ECRYPTFS_REQ_PROCESSED; | ||
| } | ||
| wake_up(&req->wait); | ||
| mutex_unlock(&req->mux); | ||
| } | ||
| mutex_unlock(&ecryptfs_kthread_ctl.mux); | ||
| } | ||
| out: | ||
| return 0; | ||
| } | ||
|
|
||
| int ecryptfs_init_kthread(void) | ||
| { | ||
| int rc = 0; | ||
|
|
||
| mutex_init(&ecryptfs_kthread_ctl.mux); | ||
| init_waitqueue_head(&ecryptfs_kthread_ctl.wait); | ||
| INIT_LIST_HEAD(&ecryptfs_kthread_ctl.req_list); | ||
| ecryptfs_kthread = kthread_run(&ecryptfs_threadfn, NULL, | ||
| "ecryptfs-kthread"); | ||
| if (IS_ERR(ecryptfs_kthread)) { | ||
| rc = PTR_ERR(ecryptfs_kthread); | ||
| printk(KERN_ERR "%s: Failed to create kernel thread; rc = [%d]" | ||
| "\n", __func__, rc); | ||
| } | ||
| return rc; | ||
| } | ||
|
|
||
| void ecryptfs_destroy_kthread(void) | ||
| { | ||
| struct ecryptfs_open_req *req; | ||
|
|
||
| mutex_lock(&ecryptfs_kthread_ctl.mux); | ||
| ecryptfs_kthread_ctl.flags |= ECRYPTFS_KTHREAD_ZOMBIE; | ||
| list_for_each_entry(req, &ecryptfs_kthread_ctl.req_list, | ||
| kthread_ctl_list) { | ||
| mutex_lock(&req->mux); | ||
| req->flags |= ECRYPTFS_REQ_ZOMBIE; | ||
| wake_up(&req->wait); | ||
| mutex_unlock(&req->mux); | ||
| } | ||
| mutex_unlock(&ecryptfs_kthread_ctl.mux); | ||
| kthread_stop(ecryptfs_kthread); | ||
| wake_up(&ecryptfs_kthread_ctl.wait); | ||
| } | ||
|
|
||
| /** | ||
| * ecryptfs_privileged_open | ||
| * @lower_file: Result of dentry_open by root on lower dentry | ||
| * @lower_dentry: Lower dentry for file to open | ||
| * @lower_mnt: Lower vfsmount for file to open | ||
| * | ||
| * This function gets a r/w file opened againt the lower dentry. | ||
| * | ||
| * Returns zero on success; non-zero otherwise | ||
| */ | ||
| int ecryptfs_privileged_open(struct file **lower_file, | ||
| struct dentry *lower_dentry, | ||
| struct vfsmount *lower_mnt) | ||
| { | ||
| struct ecryptfs_open_req *req; | ||
| int rc = 0; | ||
|
|
||
| /* Corresponding dput() and mntput() are done when the | ||
| * persistent file is fput() when the eCryptfs inode is | ||
| * destroyed. */ | ||
| dget(lower_dentry); | ||
| mntget(lower_mnt); | ||
| (*lower_file) = dentry_open(lower_dentry, lower_mnt, | ||
| (O_RDWR | O_LARGEFILE)); | ||
| if (!IS_ERR(*lower_file)) | ||
| goto out; | ||
| req = kmem_cache_alloc(ecryptfs_open_req_cache, GFP_KERNEL); | ||
| if (!req) { | ||
| rc = -ENOMEM; | ||
| goto out; | ||
| } | ||
| mutex_init(&req->mux); | ||
| req->lower_file = lower_file; | ||
| req->lower_dentry = lower_dentry; | ||
| req->lower_mnt = lower_mnt; | ||
| init_waitqueue_head(&req->wait); | ||
| req->flags = 0; | ||
| mutex_lock(&ecryptfs_kthread_ctl.mux); | ||
| if (ecryptfs_kthread_ctl.flags & ECRYPTFS_KTHREAD_ZOMBIE) { | ||
| rc = -EIO; | ||
| mutex_unlock(&ecryptfs_kthread_ctl.mux); | ||
| printk(KERN_ERR "%s: We are in the middle of shutting down; " | ||
| "aborting privileged request to open lower file\n", | ||
| __func__); | ||
| goto out_free; | ||
| } | ||
| list_add_tail(&req->kthread_ctl_list, &ecryptfs_kthread_ctl.req_list); | ||
| mutex_unlock(&ecryptfs_kthread_ctl.mux); | ||
| wake_up(&ecryptfs_kthread_ctl.wait); | ||
| wait_event(req->wait, (req->flags != 0)); | ||
| mutex_lock(&req->mux); | ||
| BUG_ON(req->flags == 0); | ||
| if (req->flags & ECRYPTFS_REQ_DROPPED | ||
| || req->flags & ECRYPTFS_REQ_ZOMBIE) { | ||
| rc = -EIO; | ||
| printk(KERN_WARNING "%s: Privileged open request dropped\n", | ||
| __func__); | ||
| goto out_unlock; | ||
| } | ||
| if (IS_ERR(*req->lower_file)) { | ||
| rc = PTR_ERR(*req->lower_file); | ||
| dget(lower_dentry); | ||
| mntget(lower_mnt); | ||
| (*lower_file) = dentry_open(lower_dentry, lower_mnt, | ||
| (O_RDONLY | O_LARGEFILE)); | ||
| if (IS_ERR(*lower_file)) { | ||
| rc = PTR_ERR(*req->lower_file); | ||
| (*lower_file) = NULL; | ||
| printk(KERN_WARNING "%s: Error attempting privileged " | ||
| "open of lower file with either RW or RO " | ||
| "perms; rc = [%d]. Giving up.\n", | ||
| __func__, rc); | ||
| } | ||
| } | ||
| out_unlock: | ||
| mutex_unlock(&req->mux); | ||
| out_free: | ||
| kmem_cache_free(ecryptfs_open_req_cache, req); | ||
| out: | ||
| return rc; | ||
| } |
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