Commit | Line | Data |
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3e93cd67 AV |
1 | #include <linux/module.h> |
2 | #include <linux/sched.h> | |
3 | #include <linux/fs.h> | |
4 | #include <linux/path.h> | |
5 | #include <linux/slab.h> | |
6 | ||
7 | /* | |
8 | * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values. | |
9 | * It can block. | |
10 | */ | |
11 | void set_fs_root(struct fs_struct *fs, struct path *path) | |
12 | { | |
13 | struct path old_root; | |
14 | ||
15 | write_lock(&fs->lock); | |
16 | old_root = fs->root; | |
17 | fs->root = *path; | |
18 | path_get(path); | |
19 | write_unlock(&fs->lock); | |
20 | if (old_root.dentry) | |
21 | path_put(&old_root); | |
22 | } | |
23 | ||
24 | /* | |
25 | * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values. | |
26 | * It can block. | |
27 | */ | |
28 | void set_fs_pwd(struct fs_struct *fs, struct path *path) | |
29 | { | |
30 | struct path old_pwd; | |
31 | ||
32 | write_lock(&fs->lock); | |
33 | old_pwd = fs->pwd; | |
34 | fs->pwd = *path; | |
35 | path_get(path); | |
36 | write_unlock(&fs->lock); | |
37 | ||
38 | if (old_pwd.dentry) | |
39 | path_put(&old_pwd); | |
40 | } | |
41 | ||
42 | void chroot_fs_refs(struct path *old_root, struct path *new_root) | |
43 | { | |
44 | struct task_struct *g, *p; | |
45 | struct fs_struct *fs; | |
46 | int count = 0; | |
47 | ||
48 | read_lock(&tasklist_lock); | |
49 | do_each_thread(g, p) { | |
50 | task_lock(p); | |
51 | fs = p->fs; | |
52 | if (fs) { | |
53 | write_lock(&fs->lock); | |
54 | if (fs->root.dentry == old_root->dentry | |
55 | && fs->root.mnt == old_root->mnt) { | |
56 | path_get(new_root); | |
57 | fs->root = *new_root; | |
58 | count++; | |
59 | } | |
60 | if (fs->pwd.dentry == old_root->dentry | |
61 | && fs->pwd.mnt == old_root->mnt) { | |
62 | path_get(new_root); | |
63 | fs->pwd = *new_root; | |
64 | count++; | |
65 | } | |
66 | write_unlock(&fs->lock); | |
67 | } | |
68 | task_unlock(p); | |
69 | } while_each_thread(g, p); | |
70 | read_unlock(&tasklist_lock); | |
71 | while (count--) | |
72 | path_put(old_root); | |
73 | } | |
74 | ||
498052bb | 75 | void free_fs_struct(struct fs_struct *fs) |
3e93cd67 | 76 | { |
498052bb AV |
77 | path_put(&fs->root); |
78 | path_put(&fs->pwd); | |
79 | kmem_cache_free(fs_cachep, fs); | |
3e93cd67 AV |
80 | } |
81 | ||
82 | void exit_fs(struct task_struct *tsk) | |
83 | { | |
498052bb | 84 | struct fs_struct *fs = tsk->fs; |
3e93cd67 AV |
85 | |
86 | if (fs) { | |
498052bb | 87 | int kill; |
3e93cd67 | 88 | task_lock(tsk); |
498052bb | 89 | write_lock(&fs->lock); |
3e93cd67 | 90 | tsk->fs = NULL; |
498052bb AV |
91 | kill = !--fs->users; |
92 | write_unlock(&fs->lock); | |
3e93cd67 | 93 | task_unlock(tsk); |
498052bb AV |
94 | if (kill) |
95 | free_fs_struct(fs); | |
3e93cd67 AV |
96 | } |
97 | } | |
98 | ||
99 | struct fs_struct *copy_fs_struct(struct fs_struct *old) | |
100 | { | |
101 | struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL); | |
102 | /* We don't need to lock fs - think why ;-) */ | |
103 | if (fs) { | |
498052bb AV |
104 | fs->users = 1; |
105 | fs->in_exec = 0; | |
3e93cd67 AV |
106 | rwlock_init(&fs->lock); |
107 | fs->umask = old->umask; | |
108 | read_lock(&old->lock); | |
109 | fs->root = old->root; | |
110 | path_get(&old->root); | |
111 | fs->pwd = old->pwd; | |
112 | path_get(&old->pwd); | |
113 | read_unlock(&old->lock); | |
114 | } | |
115 | return fs; | |
116 | } | |
117 | ||
118 | int unshare_fs_struct(void) | |
119 | { | |
498052bb AV |
120 | struct fs_struct *fs = current->fs; |
121 | struct fs_struct *new_fs = copy_fs_struct(fs); | |
122 | int kill; | |
123 | ||
124 | if (!new_fs) | |
3e93cd67 | 125 | return -ENOMEM; |
498052bb AV |
126 | |
127 | task_lock(current); | |
128 | write_lock(&fs->lock); | |
129 | kill = !--fs->users; | |
130 | current->fs = new_fs; | |
131 | write_unlock(&fs->lock); | |
132 | task_unlock(current); | |
133 | ||
134 | if (kill) | |
135 | free_fs_struct(fs); | |
136 | ||
3e93cd67 AV |
137 | return 0; |
138 | } | |
139 | EXPORT_SYMBOL_GPL(unshare_fs_struct); | |
140 | ||
ce3b0f8d AV |
141 | int current_umask(void) |
142 | { | |
143 | return current->fs->umask; | |
144 | } | |
145 | EXPORT_SYMBOL(current_umask); | |
146 | ||
3e93cd67 AV |
147 | /* to be mentioned only in INIT_TASK */ |
148 | struct fs_struct init_fs = { | |
498052bb | 149 | .users = 1, |
3e93cd67 AV |
150 | .lock = __RW_LOCK_UNLOCKED(init_fs.lock), |
151 | .umask = 0022, | |
152 | }; | |
153 | ||
154 | void daemonize_fs_struct(void) | |
155 | { | |
498052bb AV |
156 | struct fs_struct *fs = current->fs; |
157 | ||
158 | if (fs) { | |
159 | int kill; | |
160 | ||
161 | task_lock(current); | |
3e93cd67 | 162 | |
498052bb AV |
163 | write_lock(&init_fs.lock); |
164 | init_fs.users++; | |
165 | write_unlock(&init_fs.lock); | |
166 | ||
167 | write_lock(&fs->lock); | |
168 | current->fs = &init_fs; | |
169 | kill = !--fs->users; | |
170 | write_unlock(&fs->lock); | |
171 | ||
172 | task_unlock(current); | |
173 | if (kill) | |
174 | free_fs_struct(fs); | |
175 | } | |
3e93cd67 | 176 | } |