Commit | Line | Data |
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1a59d1b8 | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
746f1e55 MH |
2 | /** |
3 | * eCryptfs: Linux filesystem encryption layer | |
4 | * | |
5 | * Copyright (C) 2008 International Business Machines Corp. | |
6 | * Author(s): Michael A. Halcrow <mahalcro@us.ibm.com> | |
746f1e55 MH |
7 | */ |
8 | ||
9 | #include <linux/kthread.h> | |
10 | #include <linux/freezer.h> | |
5a0e3ad6 | 11 | #include <linux/slab.h> |
746f1e55 MH |
12 | #include <linux/wait.h> |
13 | #include <linux/mount.h> | |
14 | #include "ecryptfs_kernel.h" | |
15 | ||
3b8b4871 AV |
16 | struct ecryptfs_open_req { |
17 | struct file **lower_file; | |
765927b2 | 18 | struct path path; |
3b8b4871 AV |
19 | struct completion done; |
20 | struct list_head kthread_ctl_list; | |
21 | }; | |
746f1e55 MH |
22 | |
23 | static struct ecryptfs_kthread_ctl { | |
24 | #define ECRYPTFS_KTHREAD_ZOMBIE 0x00000001 | |
25 | u32 flags; | |
26 | struct mutex mux; | |
27 | struct list_head req_list; | |
28 | wait_queue_head_t wait; | |
29 | } ecryptfs_kthread_ctl; | |
30 | ||
31 | static struct task_struct *ecryptfs_kthread; | |
32 | ||
33 | /** | |
34 | * ecryptfs_threadfn | |
35 | * @ignored: ignored | |
36 | * | |
37 | * The eCryptfs kernel thread that has the responsibility of getting | |
332ab16f | 38 | * the lower file with RW permissions. |
746f1e55 MH |
39 | * |
40 | * Returns zero on success; non-zero otherwise | |
41 | */ | |
42 | static int ecryptfs_threadfn(void *ignored) | |
43 | { | |
44 | set_freezable(); | |
45 | while (1) { | |
46 | struct ecryptfs_open_req *req; | |
47 | ||
48 | wait_event_freezable( | |
49 | ecryptfs_kthread_ctl.wait, | |
50 | (!list_empty(&ecryptfs_kthread_ctl.req_list) | |
51 | || kthread_should_stop())); | |
52 | mutex_lock(&ecryptfs_kthread_ctl.mux); | |
53 | if (ecryptfs_kthread_ctl.flags & ECRYPTFS_KTHREAD_ZOMBIE) { | |
54 | mutex_unlock(&ecryptfs_kthread_ctl.mux); | |
55 | goto out; | |
56 | } | |
57 | while (!list_empty(&ecryptfs_kthread_ctl.req_list)) { | |
58 | req = list_first_entry(&ecryptfs_kthread_ctl.req_list, | |
59 | struct ecryptfs_open_req, | |
60 | kthread_ctl_list); | |
746f1e55 | 61 | list_del(&req->kthread_ctl_list); |
765927b2 | 62 | *req->lower_file = dentry_open(&req->path, |
3b8b4871 AV |
63 | (O_RDWR | O_LARGEFILE), current_cred()); |
64 | complete(&req->done); | |
746f1e55 MH |
65 | } |
66 | mutex_unlock(&ecryptfs_kthread_ctl.mux); | |
67 | } | |
68 | out: | |
69 | return 0; | |
70 | } | |
71 | ||
7371a382 | 72 | int __init ecryptfs_init_kthread(void) |
746f1e55 MH |
73 | { |
74 | int rc = 0; | |
75 | ||
76 | mutex_init(&ecryptfs_kthread_ctl.mux); | |
77 | init_waitqueue_head(&ecryptfs_kthread_ctl.wait); | |
78 | INIT_LIST_HEAD(&ecryptfs_kthread_ctl.req_list); | |
79 | ecryptfs_kthread = kthread_run(&ecryptfs_threadfn, NULL, | |
80 | "ecryptfs-kthread"); | |
81 | if (IS_ERR(ecryptfs_kthread)) { | |
82 | rc = PTR_ERR(ecryptfs_kthread); | |
83 | printk(KERN_ERR "%s: Failed to create kernel thread; rc = [%d]" | |
84 | "\n", __func__, rc); | |
85 | } | |
86 | return rc; | |
87 | } | |
88 | ||
89 | void ecryptfs_destroy_kthread(void) | |
90 | { | |
8bbca57c | 91 | struct ecryptfs_open_req *req, *tmp; |
746f1e55 MH |
92 | |
93 | mutex_lock(&ecryptfs_kthread_ctl.mux); | |
94 | ecryptfs_kthread_ctl.flags |= ECRYPTFS_KTHREAD_ZOMBIE; | |
8bbca57c WY |
95 | list_for_each_entry_safe(req, tmp, &ecryptfs_kthread_ctl.req_list, |
96 | kthread_ctl_list) { | |
3b8b4871 AV |
97 | list_del(&req->kthread_ctl_list); |
98 | *req->lower_file = ERR_PTR(-EIO); | |
99 | complete(&req->done); | |
746f1e55 MH |
100 | } |
101 | mutex_unlock(&ecryptfs_kthread_ctl.mux); | |
102 | kthread_stop(ecryptfs_kthread); | |
103 | wake_up(&ecryptfs_kthread_ctl.wait); | |
104 | } | |
105 | ||
106 | /** | |
107 | * ecryptfs_privileged_open | |
108 | * @lower_file: Result of dentry_open by root on lower dentry | |
109 | * @lower_dentry: Lower dentry for file to open | |
110 | * @lower_mnt: Lower vfsmount for file to open | |
111 | * | |
57366a8d | 112 | * This function gets a r/w file opened against the lower dentry. |
746f1e55 MH |
113 | * |
114 | * Returns zero on success; non-zero otherwise | |
115 | */ | |
116 | int ecryptfs_privileged_open(struct file **lower_file, | |
117 | struct dentry *lower_dentry, | |
745ca247 DH |
118 | struct vfsmount *lower_mnt, |
119 | const struct cred *cred) | |
746f1e55 | 120 | { |
3b8b4871 | 121 | struct ecryptfs_open_req req; |
ac22ba23 | 122 | int flags = O_LARGEFILE; |
746f1e55 MH |
123 | int rc = 0; |
124 | ||
765927b2 AV |
125 | init_completion(&req.done); |
126 | req.lower_file = lower_file; | |
127 | req.path.dentry = lower_dentry; | |
128 | req.path.mnt = lower_mnt; | |
129 | ||
746f1e55 | 130 | /* Corresponding dput() and mntput() are done when the |
332ab16f TH |
131 | * lower file is fput() when all eCryptfs files for the inode are |
132 | * released. */ | |
2b0143b5 | 133 | flags |= IS_RDONLY(d_inode(lower_dentry)) ? O_RDONLY : O_RDWR; |
765927b2 | 134 | (*lower_file) = dentry_open(&req.path, flags, cred); |
746f1e55 | 135 | if (!IS_ERR(*lower_file)) |
78c4e172 | 136 | goto out; |
9fe79d76 | 137 | if ((flags & O_ACCMODE) == O_RDONLY) { |
ac22ba23 TH |
138 | rc = PTR_ERR((*lower_file)); |
139 | goto out; | |
140 | } | |
746f1e55 MH |
141 | mutex_lock(&ecryptfs_kthread_ctl.mux); |
142 | if (ecryptfs_kthread_ctl.flags & ECRYPTFS_KTHREAD_ZOMBIE) { | |
143 | rc = -EIO; | |
144 | mutex_unlock(&ecryptfs_kthread_ctl.mux); | |
145 | printk(KERN_ERR "%s: We are in the middle of shutting down; " | |
146 | "aborting privileged request to open lower file\n", | |
147 | __func__); | |
3b8b4871 | 148 | goto out; |
746f1e55 | 149 | } |
3b8b4871 | 150 | list_add_tail(&req.kthread_ctl_list, &ecryptfs_kthread_ctl.req_list); |
746f1e55 MH |
151 | mutex_unlock(&ecryptfs_kthread_ctl.mux); |
152 | wake_up(&ecryptfs_kthread_ctl.wait); | |
3b8b4871 | 153 | wait_for_completion(&req.done); |
78c4e172 | 154 | if (IS_ERR(*lower_file)) |
3b8b4871 | 155 | rc = PTR_ERR(*lower_file); |
746f1e55 MH |
156 | out: |
157 | return rc; | |
158 | } |