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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> |
f03c6599 AV |
7 | #include "internal.h" |
8 | ||
9 | static inline void path_get_longterm(struct path *path) | |
10 | { | |
11 | path_get(path); | |
12 | mnt_make_longterm(path->mnt); | |
13 | } | |
14 | ||
15 | static inline void path_put_longterm(struct path *path) | |
16 | { | |
17 | mnt_make_shortterm(path->mnt); | |
18 | path_put(path); | |
19 | } | |
3e93cd67 AV |
20 | |
21 | /* | |
22 | * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values. | |
23 | * It can block. | |
24 | */ | |
25 | void set_fs_root(struct fs_struct *fs, struct path *path) | |
26 | { | |
27 | struct path old_root; | |
28 | ||
2a4419b5 | 29 | spin_lock(&fs->lock); |
c28cc364 | 30 | write_seqcount_begin(&fs->seq); |
3e93cd67 AV |
31 | old_root = fs->root; |
32 | fs->root = *path; | |
f03c6599 | 33 | path_get_longterm(path); |
c28cc364 | 34 | write_seqcount_end(&fs->seq); |
2a4419b5 | 35 | spin_unlock(&fs->lock); |
3e93cd67 | 36 | if (old_root.dentry) |
f03c6599 | 37 | path_put_longterm(&old_root); |
3e93cd67 AV |
38 | } |
39 | ||
40 | /* | |
41 | * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values. | |
42 | * It can block. | |
43 | */ | |
44 | void set_fs_pwd(struct fs_struct *fs, struct path *path) | |
45 | { | |
46 | struct path old_pwd; | |
47 | ||
2a4419b5 | 48 | spin_lock(&fs->lock); |
c28cc364 | 49 | write_seqcount_begin(&fs->seq); |
3e93cd67 AV |
50 | old_pwd = fs->pwd; |
51 | fs->pwd = *path; | |
f03c6599 | 52 | path_get_longterm(path); |
c28cc364 | 53 | write_seqcount_end(&fs->seq); |
2a4419b5 | 54 | spin_unlock(&fs->lock); |
3e93cd67 AV |
55 | |
56 | if (old_pwd.dentry) | |
f03c6599 | 57 | path_put_longterm(&old_pwd); |
3e93cd67 AV |
58 | } |
59 | ||
60 | void chroot_fs_refs(struct path *old_root, struct path *new_root) | |
61 | { | |
62 | struct task_struct *g, *p; | |
63 | struct fs_struct *fs; | |
64 | int count = 0; | |
65 | ||
66 | read_lock(&tasklist_lock); | |
67 | do_each_thread(g, p) { | |
68 | task_lock(p); | |
69 | fs = p->fs; | |
70 | if (fs) { | |
2a4419b5 | 71 | spin_lock(&fs->lock); |
c28cc364 | 72 | write_seqcount_begin(&fs->seq); |
3e93cd67 AV |
73 | if (fs->root.dentry == old_root->dentry |
74 | && fs->root.mnt == old_root->mnt) { | |
f03c6599 | 75 | path_get_longterm(new_root); |
3e93cd67 AV |
76 | fs->root = *new_root; |
77 | count++; | |
78 | } | |
79 | if (fs->pwd.dentry == old_root->dentry | |
80 | && fs->pwd.mnt == old_root->mnt) { | |
f03c6599 | 81 | path_get_longterm(new_root); |
3e93cd67 AV |
82 | fs->pwd = *new_root; |
83 | count++; | |
84 | } | |
c28cc364 | 85 | write_seqcount_end(&fs->seq); |
2a4419b5 | 86 | spin_unlock(&fs->lock); |
3e93cd67 AV |
87 | } |
88 | task_unlock(p); | |
89 | } while_each_thread(g, p); | |
90 | read_unlock(&tasklist_lock); | |
91 | while (count--) | |
f03c6599 | 92 | path_put_longterm(old_root); |
3e93cd67 AV |
93 | } |
94 | ||
498052bb | 95 | void free_fs_struct(struct fs_struct *fs) |
3e93cd67 | 96 | { |
f03c6599 AV |
97 | path_put_longterm(&fs->root); |
98 | path_put_longterm(&fs->pwd); | |
498052bb | 99 | kmem_cache_free(fs_cachep, fs); |
3e93cd67 AV |
100 | } |
101 | ||
102 | void exit_fs(struct task_struct *tsk) | |
103 | { | |
498052bb | 104 | struct fs_struct *fs = tsk->fs; |
3e93cd67 AV |
105 | |
106 | if (fs) { | |
498052bb | 107 | int kill; |
3e93cd67 | 108 | task_lock(tsk); |
2a4419b5 | 109 | spin_lock(&fs->lock); |
3e93cd67 | 110 | tsk->fs = NULL; |
498052bb | 111 | kill = !--fs->users; |
2a4419b5 | 112 | spin_unlock(&fs->lock); |
3e93cd67 | 113 | task_unlock(tsk); |
498052bb AV |
114 | if (kill) |
115 | free_fs_struct(fs); | |
3e93cd67 AV |
116 | } |
117 | } | |
118 | ||
119 | struct fs_struct *copy_fs_struct(struct fs_struct *old) | |
120 | { | |
121 | struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL); | |
122 | /* We don't need to lock fs - think why ;-) */ | |
123 | if (fs) { | |
498052bb AV |
124 | fs->users = 1; |
125 | fs->in_exec = 0; | |
2a4419b5 | 126 | spin_lock_init(&fs->lock); |
c28cc364 | 127 | seqcount_init(&fs->seq); |
3e93cd67 | 128 | fs->umask = old->umask; |
b3e19d92 NP |
129 | |
130 | spin_lock(&old->lock); | |
131 | fs->root = old->root; | |
f03c6599 | 132 | path_get_longterm(&fs->root); |
b3e19d92 | 133 | fs->pwd = old->pwd; |
f03c6599 | 134 | path_get_longterm(&fs->pwd); |
b3e19d92 | 135 | spin_unlock(&old->lock); |
3e93cd67 AV |
136 | } |
137 | return fs; | |
138 | } | |
139 | ||
140 | int unshare_fs_struct(void) | |
141 | { | |
498052bb AV |
142 | struct fs_struct *fs = current->fs; |
143 | struct fs_struct *new_fs = copy_fs_struct(fs); | |
144 | int kill; | |
145 | ||
146 | if (!new_fs) | |
3e93cd67 | 147 | return -ENOMEM; |
498052bb AV |
148 | |
149 | task_lock(current); | |
2a4419b5 | 150 | spin_lock(&fs->lock); |
498052bb AV |
151 | kill = !--fs->users; |
152 | current->fs = new_fs; | |
2a4419b5 | 153 | spin_unlock(&fs->lock); |
498052bb AV |
154 | task_unlock(current); |
155 | ||
156 | if (kill) | |
157 | free_fs_struct(fs); | |
158 | ||
3e93cd67 AV |
159 | return 0; |
160 | } | |
161 | EXPORT_SYMBOL_GPL(unshare_fs_struct); | |
162 | ||
ce3b0f8d AV |
163 | int current_umask(void) |
164 | { | |
165 | return current->fs->umask; | |
166 | } | |
167 | EXPORT_SYMBOL(current_umask); | |
168 | ||
3e93cd67 AV |
169 | /* to be mentioned only in INIT_TASK */ |
170 | struct fs_struct init_fs = { | |
498052bb | 171 | .users = 1, |
2a4419b5 | 172 | .lock = __SPIN_LOCK_UNLOCKED(init_fs.lock), |
c28cc364 | 173 | .seq = SEQCNT_ZERO, |
3e93cd67 AV |
174 | .umask = 0022, |
175 | }; | |
176 | ||
177 | void daemonize_fs_struct(void) | |
178 | { | |
498052bb AV |
179 | struct fs_struct *fs = current->fs; |
180 | ||
181 | if (fs) { | |
182 | int kill; | |
183 | ||
184 | task_lock(current); | |
3e93cd67 | 185 | |
2a4419b5 | 186 | spin_lock(&init_fs.lock); |
498052bb | 187 | init_fs.users++; |
2a4419b5 | 188 | spin_unlock(&init_fs.lock); |
498052bb | 189 | |
2a4419b5 | 190 | spin_lock(&fs->lock); |
498052bb AV |
191 | current->fs = &init_fs; |
192 | kill = !--fs->users; | |
2a4419b5 | 193 | spin_unlock(&fs->lock); |
498052bb AV |
194 | |
195 | task_unlock(current); | |
196 | if (kill) | |
197 | free_fs_struct(fs); | |
198 | } | |
3e93cd67 | 199 | } |