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); |
c28cc364 | 17 | write_seqcount_begin(&fs->seq); |
3e93cd67 AV |
18 | old_root = fs->root; |
19 | fs->root = *path; | |
20 | path_get(path); | |
c28cc364 | 21 | write_seqcount_end(&fs->seq); |
2a4419b5 | 22 | spin_unlock(&fs->lock); |
3e93cd67 AV |
23 | if (old_root.dentry) |
24 | path_put(&old_root); | |
25 | } | |
26 | ||
27 | /* | |
28 | * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values. | |
29 | * It can block. | |
30 | */ | |
31 | void set_fs_pwd(struct fs_struct *fs, struct path *path) | |
32 | { | |
33 | struct path old_pwd; | |
34 | ||
2a4419b5 | 35 | spin_lock(&fs->lock); |
c28cc364 | 36 | write_seqcount_begin(&fs->seq); |
3e93cd67 AV |
37 | old_pwd = fs->pwd; |
38 | fs->pwd = *path; | |
39 | path_get(path); | |
c28cc364 | 40 | write_seqcount_end(&fs->seq); |
2a4419b5 | 41 | spin_unlock(&fs->lock); |
3e93cd67 AV |
42 | |
43 | if (old_pwd.dentry) | |
44 | path_put(&old_pwd); | |
45 | } | |
46 | ||
47 | void chroot_fs_refs(struct path *old_root, struct path *new_root) | |
48 | { | |
49 | struct task_struct *g, *p; | |
50 | struct fs_struct *fs; | |
51 | int count = 0; | |
52 | ||
53 | read_lock(&tasklist_lock); | |
54 | do_each_thread(g, p) { | |
55 | task_lock(p); | |
56 | fs = p->fs; | |
57 | if (fs) { | |
2a4419b5 | 58 | spin_lock(&fs->lock); |
c28cc364 | 59 | write_seqcount_begin(&fs->seq); |
3e93cd67 AV |
60 | if (fs->root.dentry == old_root->dentry |
61 | && fs->root.mnt == old_root->mnt) { | |
62 | path_get(new_root); | |
63 | fs->root = *new_root; | |
64 | count++; | |
65 | } | |
66 | if (fs->pwd.dentry == old_root->dentry | |
67 | && fs->pwd.mnt == old_root->mnt) { | |
68 | path_get(new_root); | |
69 | fs->pwd = *new_root; | |
70 | count++; | |
71 | } | |
c28cc364 | 72 | write_seqcount_end(&fs->seq); |
2a4419b5 | 73 | spin_unlock(&fs->lock); |
3e93cd67 AV |
74 | } |
75 | task_unlock(p); | |
76 | } while_each_thread(g, p); | |
77 | read_unlock(&tasklist_lock); | |
78 | while (count--) | |
79 | path_put(old_root); | |
80 | } | |
81 | ||
498052bb | 82 | void free_fs_struct(struct fs_struct *fs) |
3e93cd67 | 83 | { |
498052bb AV |
84 | path_put(&fs->root); |
85 | path_put(&fs->pwd); | |
86 | kmem_cache_free(fs_cachep, fs); | |
3e93cd67 AV |
87 | } |
88 | ||
89 | void exit_fs(struct task_struct *tsk) | |
90 | { | |
498052bb | 91 | struct fs_struct *fs = tsk->fs; |
3e93cd67 AV |
92 | |
93 | if (fs) { | |
498052bb | 94 | int kill; |
3e93cd67 | 95 | task_lock(tsk); |
2a4419b5 | 96 | spin_lock(&fs->lock); |
c28cc364 | 97 | write_seqcount_begin(&fs->seq); |
3e93cd67 | 98 | tsk->fs = NULL; |
498052bb | 99 | kill = !--fs->users; |
c28cc364 | 100 | write_seqcount_end(&fs->seq); |
2a4419b5 | 101 | spin_unlock(&fs->lock); |
3e93cd67 | 102 | task_unlock(tsk); |
498052bb AV |
103 | if (kill) |
104 | free_fs_struct(fs); | |
3e93cd67 AV |
105 | } |
106 | } | |
107 | ||
108 | struct fs_struct *copy_fs_struct(struct fs_struct *old) | |
109 | { | |
110 | struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL); | |
111 | /* We don't need to lock fs - think why ;-) */ | |
112 | if (fs) { | |
498052bb AV |
113 | fs->users = 1; |
114 | fs->in_exec = 0; | |
2a4419b5 | 115 | spin_lock_init(&fs->lock); |
c28cc364 | 116 | seqcount_init(&fs->seq); |
3e93cd67 | 117 | fs->umask = old->umask; |
f7ad3c6b | 118 | get_fs_root_and_pwd(old, &fs->root, &fs->pwd); |
3e93cd67 AV |
119 | } |
120 | return fs; | |
121 | } | |
122 | ||
123 | int unshare_fs_struct(void) | |
124 | { | |
498052bb AV |
125 | struct fs_struct *fs = current->fs; |
126 | struct fs_struct *new_fs = copy_fs_struct(fs); | |
127 | int kill; | |
128 | ||
129 | if (!new_fs) | |
3e93cd67 | 130 | return -ENOMEM; |
498052bb AV |
131 | |
132 | task_lock(current); | |
2a4419b5 | 133 | spin_lock(&fs->lock); |
498052bb AV |
134 | kill = !--fs->users; |
135 | current->fs = new_fs; | |
2a4419b5 | 136 | spin_unlock(&fs->lock); |
498052bb AV |
137 | task_unlock(current); |
138 | ||
139 | if (kill) | |
140 | free_fs_struct(fs); | |
141 | ||
3e93cd67 AV |
142 | return 0; |
143 | } | |
144 | EXPORT_SYMBOL_GPL(unshare_fs_struct); | |
145 | ||
ce3b0f8d AV |
146 | int current_umask(void) |
147 | { | |
148 | return current->fs->umask; | |
149 | } | |
150 | EXPORT_SYMBOL(current_umask); | |
151 | ||
3e93cd67 AV |
152 | /* to be mentioned only in INIT_TASK */ |
153 | struct fs_struct init_fs = { | |
498052bb | 154 | .users = 1, |
2a4419b5 | 155 | .lock = __SPIN_LOCK_UNLOCKED(init_fs.lock), |
c28cc364 | 156 | .seq = SEQCNT_ZERO, |
3e93cd67 AV |
157 | .umask = 0022, |
158 | }; | |
159 | ||
160 | void daemonize_fs_struct(void) | |
161 | { | |
498052bb AV |
162 | struct fs_struct *fs = current->fs; |
163 | ||
164 | if (fs) { | |
165 | int kill; | |
166 | ||
167 | task_lock(current); | |
3e93cd67 | 168 | |
2a4419b5 | 169 | spin_lock(&init_fs.lock); |
498052bb | 170 | init_fs.users++; |
2a4419b5 | 171 | spin_unlock(&init_fs.lock); |
498052bb | 172 | |
2a4419b5 | 173 | spin_lock(&fs->lock); |
498052bb AV |
174 | current->fs = &init_fs; |
175 | kill = !--fs->users; | |
2a4419b5 | 176 | spin_unlock(&fs->lock); |
498052bb AV |
177 | |
178 | task_unlock(current); | |
179 | if (kill) | |
180 | free_fs_struct(fs); | |
181 | } | |
3e93cd67 | 182 | } |