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> | |
5ad4e53b | 6 | #include <linux/fs_struct.h> |
3e93cd67 AV |
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 | ||
2a4419b5 | 16 | spin_lock(&fs->lock); |
3e93cd67 AV |
17 | old_root = fs->root; |
18 | fs->root = *path; | |
19 | path_get(path); | |
2a4419b5 | 20 | spin_unlock(&fs->lock); |
3e93cd67 AV |
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 | ||
2a4419b5 | 33 | spin_lock(&fs->lock); |
3e93cd67 AV |
34 | old_pwd = fs->pwd; |
35 | fs->pwd = *path; | |
36 | path_get(path); | |
2a4419b5 | 37 | spin_unlock(&fs->lock); |
3e93cd67 AV |
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) { | |
2a4419b5 | 54 | spin_lock(&fs->lock); |
3e93cd67 AV |
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 | } | |
2a4419b5 | 67 | spin_unlock(&fs->lock); |
3e93cd67 AV |
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 | ||
498052bb | 76 | void free_fs_struct(struct fs_struct *fs) |
3e93cd67 | 77 | { |
498052bb AV |
78 | path_put(&fs->root); |
79 | path_put(&fs->pwd); | |
80 | kmem_cache_free(fs_cachep, fs); | |
3e93cd67 AV |
81 | } |
82 | ||
83 | void exit_fs(struct task_struct *tsk) | |
84 | { | |
498052bb | 85 | struct fs_struct *fs = tsk->fs; |
3e93cd67 AV |
86 | |
87 | if (fs) { | |
498052bb | 88 | int kill; |
3e93cd67 | 89 | task_lock(tsk); |
2a4419b5 | 90 | spin_lock(&fs->lock); |
3e93cd67 | 91 | tsk->fs = NULL; |
498052bb | 92 | kill = !--fs->users; |
2a4419b5 | 93 | spin_unlock(&fs->lock); |
3e93cd67 | 94 | task_unlock(tsk); |
498052bb AV |
95 | if (kill) |
96 | free_fs_struct(fs); | |
3e93cd67 AV |
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) { | |
498052bb AV |
105 | fs->users = 1; |
106 | fs->in_exec = 0; | |
2a4419b5 | 107 | spin_lock_init(&fs->lock); |
3e93cd67 | 108 | fs->umask = old->umask; |
f7ad3c6b | 109 | get_fs_root_and_pwd(old, &fs->root, &fs->pwd); |
3e93cd67 AV |
110 | } |
111 | return fs; | |
112 | } | |
113 | ||
114 | int unshare_fs_struct(void) | |
115 | { | |
498052bb AV |
116 | struct fs_struct *fs = current->fs; |
117 | struct fs_struct *new_fs = copy_fs_struct(fs); | |
118 | int kill; | |
119 | ||
120 | if (!new_fs) | |
3e93cd67 | 121 | return -ENOMEM; |
498052bb AV |
122 | |
123 | task_lock(current); | |
2a4419b5 | 124 | spin_lock(&fs->lock); |
498052bb AV |
125 | kill = !--fs->users; |
126 | current->fs = new_fs; | |
2a4419b5 | 127 | spin_unlock(&fs->lock); |
498052bb AV |
128 | task_unlock(current); |
129 | ||
130 | if (kill) | |
131 | free_fs_struct(fs); | |
132 | ||
3e93cd67 AV |
133 | return 0; |
134 | } | |
135 | EXPORT_SYMBOL_GPL(unshare_fs_struct); | |
136 | ||
ce3b0f8d AV |
137 | int current_umask(void) |
138 | { | |
139 | return current->fs->umask; | |
140 | } | |
141 | EXPORT_SYMBOL(current_umask); | |
142 | ||
3e93cd67 AV |
143 | /* to be mentioned only in INIT_TASK */ |
144 | struct fs_struct init_fs = { | |
498052bb | 145 | .users = 1, |
2a4419b5 | 146 | .lock = __SPIN_LOCK_UNLOCKED(init_fs.lock), |
3e93cd67 AV |
147 | .umask = 0022, |
148 | }; | |
149 | ||
150 | void daemonize_fs_struct(void) | |
151 | { | |
498052bb AV |
152 | struct fs_struct *fs = current->fs; |
153 | ||
154 | if (fs) { | |
155 | int kill; | |
156 | ||
157 | task_lock(current); | |
3e93cd67 | 158 | |
2a4419b5 | 159 | spin_lock(&init_fs.lock); |
498052bb | 160 | init_fs.users++; |
2a4419b5 | 161 | spin_unlock(&init_fs.lock); |
498052bb | 162 | |
2a4419b5 | 163 | spin_lock(&fs->lock); |
498052bb AV |
164 | current->fs = &init_fs; |
165 | kill = !--fs->users; | |
2a4419b5 | 166 | spin_unlock(&fs->lock); |
498052bb AV |
167 | |
168 | task_unlock(current); | |
169 | if (kill) | |
170 | free_fs_struct(fs); | |
171 | } | |
3e93cd67 | 172 | } |