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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 | #include <linux/fs_struct.h> |
7 | |
8 | /* |
9 | * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values. |
10 | * It can block. |
11 | */ |
12 | void set_fs_root(struct fs_struct *fs, struct path *path) |
13 | { |
14 | struct path old_root; |
15 | |
16 | write_lock(&fs->lock); |
17 | old_root = fs->root; |
18 | fs->root = *path; |
19 | path_get(path); |
20 | write_unlock(&fs->lock); |
21 | if (old_root.dentry) |
22 | path_put(&old_root); |
23 | } |
24 | |
25 | /* |
26 | * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values. |
27 | * It can block. |
28 | */ |
29 | void set_fs_pwd(struct fs_struct *fs, struct path *path) |
30 | { |
31 | struct path old_pwd; |
32 | |
33 | write_lock(&fs->lock); |
34 | old_pwd = fs->pwd; |
35 | fs->pwd = *path; |
36 | path_get(path); |
37 | write_unlock(&fs->lock); |
38 | |
39 | if (old_pwd.dentry) |
40 | path_put(&old_pwd); |
41 | } |
42 | |
43 | void chroot_fs_refs(struct path *old_root, struct path *new_root) |
44 | { |
45 | struct task_struct *g, *p; |
46 | struct fs_struct *fs; |
47 | int count = 0; |
48 | |
49 | read_lock(&tasklist_lock); |
50 | do_each_thread(g, p) { |
51 | task_lock(p); |
52 | fs = p->fs; |
53 | if (fs) { |
54 | write_lock(&fs->lock); |
55 | if (fs->root.dentry == old_root->dentry |
56 | && fs->root.mnt == old_root->mnt) { |
57 | path_get(new_root); |
58 | fs->root = *new_root; |
59 | count++; |
60 | } |
61 | if (fs->pwd.dentry == old_root->dentry |
62 | && fs->pwd.mnt == old_root->mnt) { |
63 | path_get(new_root); |
64 | fs->pwd = *new_root; |
65 | count++; |
66 | } |
67 | write_unlock(&fs->lock); |
68 | } |
69 | task_unlock(p); |
70 | } while_each_thread(g, p); |
71 | read_unlock(&tasklist_lock); |
72 | while (count--) |
73 | path_put(old_root); |
74 | } |
75 | |
76 | void free_fs_struct(struct fs_struct *fs) |
77 | { |
78 | path_put(&fs->root); |
79 | path_put(&fs->pwd); |
80 | kmem_cache_free(fs_cachep, fs); |
81 | } |
82 | |
83 | void exit_fs(struct task_struct *tsk) |
84 | { |
85 | struct fs_struct *fs = tsk->fs; |
86 | |
87 | if (fs) { |
88 | int kill; |
89 | task_lock(tsk); |
90 | write_lock(&fs->lock); |
91 | tsk->fs = NULL; |
92 | kill = !--fs->users; |
93 | write_unlock(&fs->lock); |
94 | task_unlock(tsk); |
95 | if (kill) |
96 | free_fs_struct(fs); |
97 | } |
98 | } |
99 | |
100 | struct fs_struct *copy_fs_struct(struct fs_struct *old) |
101 | { |
102 | struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL); |
103 | /* We don't need to lock fs - think why ;-) */ |
104 | if (fs) { |
105 | fs->users = 1; |
106 | fs->in_exec = 0; |
107 | rwlock_init(&fs->lock); |
108 | fs->umask = old->umask; |
109 | read_lock(&old->lock); |
110 | fs->root = old->root; |
111 | path_get(&old->root); |
112 | fs->pwd = old->pwd; |
113 | path_get(&old->pwd); |
114 | read_unlock(&old->lock); |
115 | } |
116 | return fs; |
117 | } |
118 | |
119 | int unshare_fs_struct(void) |
120 | { |
121 | struct fs_struct *fs = current->fs; |
122 | struct fs_struct *new_fs = copy_fs_struct(fs); |
123 | int kill; |
124 | |
125 | if (!new_fs) |
126 | return -ENOMEM; |
127 | |
128 | task_lock(current); |
129 | write_lock(&fs->lock); |
130 | kill = !--fs->users; |
131 | current->fs = new_fs; |
132 | write_unlock(&fs->lock); |
133 | task_unlock(current); |
134 | |
135 | if (kill) |
136 | free_fs_struct(fs); |
137 | |
138 | return 0; |
139 | } |
140 | EXPORT_SYMBOL_GPL(unshare_fs_struct); |
141 | |
142 | int current_umask(void) |
143 | { |
144 | return current->fs->umask; |
145 | } |
146 | EXPORT_SYMBOL(current_umask); |
147 | |
148 | /* to be mentioned only in INIT_TASK */ |
149 | struct fs_struct init_fs = { |
150 | .users = 1, |
151 | .lock = __RW_LOCK_UNLOCKED(init_fs.lock), |
152 | .umask = 0022, |
153 | }; |
154 | |
155 | void daemonize_fs_struct(void) |
156 | { |
157 | struct fs_struct *fs = current->fs; |
158 | |
159 | if (fs) { |
160 | int kill; |
161 | |
162 | task_lock(current); |
163 | |
164 | write_lock(&init_fs.lock); |
165 | init_fs.users++; |
166 | write_unlock(&init_fs.lock); |
167 | |
168 | write_lock(&fs->lock); |
169 | current->fs = &init_fs; |
170 | kill = !--fs->users; |
171 | write_unlock(&fs->lock); |
172 | |
173 | task_unlock(current); |
174 | if (kill) |
175 | free_fs_struct(fs); |
176 | } |
177 | } |
178 |
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
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v3.9