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Original file line number | Diff line number | Diff line change |
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#include <linux/module.h> | ||
#include <linux/sched.h> | ||
#include <linux/fs.h> | ||
#include <linux/path.h> | ||
#include <linux/slab.h> | ||
#include <linux/fs_struct.h> | ||
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/* | ||
* Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values. | ||
* It can block. | ||
*/ | ||
void set_fs_root(struct fs_struct *fs, struct path *path) | ||
{ | ||
struct path old_root; | ||
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write_lock(&fs->lock); | ||
old_root = fs->root; | ||
fs->root = *path; | ||
path_get(path); | ||
write_unlock(&fs->lock); | ||
if (old_root.dentry) | ||
path_put(&old_root); | ||
} | ||
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/* | ||
* Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values. | ||
* It can block. | ||
*/ | ||
void set_fs_pwd(struct fs_struct *fs, struct path *path) | ||
{ | ||
struct path old_pwd; | ||
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write_lock(&fs->lock); | ||
old_pwd = fs->pwd; | ||
fs->pwd = *path; | ||
path_get(path); | ||
write_unlock(&fs->lock); | ||
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if (old_pwd.dentry) | ||
path_put(&old_pwd); | ||
} | ||
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void chroot_fs_refs(struct path *old_root, struct path *new_root) | ||
{ | ||
struct task_struct *g, *p; | ||
struct fs_struct *fs; | ||
int count = 0; | ||
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read_lock(&tasklist_lock); | ||
do_each_thread(g, p) { | ||
task_lock(p); | ||
fs = p->fs; | ||
if (fs) { | ||
write_lock(&fs->lock); | ||
if (fs->root.dentry == old_root->dentry | ||
&& fs->root.mnt == old_root->mnt) { | ||
path_get(new_root); | ||
fs->root = *new_root; | ||
count++; | ||
} | ||
if (fs->pwd.dentry == old_root->dentry | ||
&& fs->pwd.mnt == old_root->mnt) { | ||
path_get(new_root); | ||
fs->pwd = *new_root; | ||
count++; | ||
} | ||
write_unlock(&fs->lock); | ||
} | ||
task_unlock(p); | ||
} while_each_thread(g, p); | ||
read_unlock(&tasklist_lock); | ||
while (count--) | ||
path_put(old_root); | ||
} | ||
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void free_fs_struct(struct fs_struct *fs) | ||
{ | ||
path_put(&fs->root); | ||
path_put(&fs->pwd); | ||
kmem_cache_free(fs_cachep, fs); | ||
} | ||
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void exit_fs(struct task_struct *tsk) | ||
{ | ||
struct fs_struct *fs = tsk->fs; | ||
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if (fs) { | ||
int kill; | ||
task_lock(tsk); | ||
write_lock(&fs->lock); | ||
tsk->fs = NULL; | ||
kill = !--fs->users; | ||
write_unlock(&fs->lock); | ||
task_unlock(tsk); | ||
if (kill) | ||
free_fs_struct(fs); | ||
} | ||
} | ||
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struct fs_struct *copy_fs_struct(struct fs_struct *old) | ||
{ | ||
struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL); | ||
/* We don't need to lock fs - think why ;-) */ | ||
if (fs) { | ||
fs->users = 1; | ||
fs->in_exec = 0; | ||
rwlock_init(&fs->lock); | ||
fs->umask = old->umask; | ||
read_lock(&old->lock); | ||
fs->root = old->root; | ||
path_get(&old->root); | ||
fs->pwd = old->pwd; | ||
path_get(&old->pwd); | ||
read_unlock(&old->lock); | ||
} | ||
return fs; | ||
} | ||
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int unshare_fs_struct(void) | ||
{ | ||
struct fs_struct *fs = current->fs; | ||
struct fs_struct *new_fs = copy_fs_struct(fs); | ||
int kill; | ||
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if (!new_fs) | ||
return -ENOMEM; | ||
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task_lock(current); | ||
write_lock(&fs->lock); | ||
kill = !--fs->users; | ||
current->fs = new_fs; | ||
write_unlock(&fs->lock); | ||
task_unlock(current); | ||
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if (kill) | ||
free_fs_struct(fs); | ||
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return 0; | ||
} | ||
EXPORT_SYMBOL_GPL(unshare_fs_struct); | ||
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int current_umask(void) | ||
{ | ||
return current->fs->umask; | ||
} | ||
EXPORT_SYMBOL(current_umask); | ||
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/* to be mentioned only in INIT_TASK */ | ||
struct fs_struct init_fs = { | ||
.users = 1, | ||
.lock = __RW_LOCK_UNLOCKED(init_fs.lock), | ||
.umask = 0022, | ||
}; | ||
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void daemonize_fs_struct(void) | ||
{ | ||
struct fs_struct *fs = current->fs; | ||
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if (fs) { | ||
int kill; | ||
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task_lock(current); | ||
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write_lock(&init_fs.lock); | ||
init_fs.users++; | ||
write_unlock(&init_fs.lock); | ||
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write_lock(&fs->lock); | ||
current->fs = &init_fs; | ||
kill = !--fs->users; | ||
write_unlock(&fs->lock); | ||
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task_unlock(current); | ||
if (kill) | ||
free_fs_struct(fs); | ||
} | ||
} |
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