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8#include <linux/string.h>
9#include <linux/slab.h>
10#include <linux/file.h>
11#include <linux/fdtable.h>
12#include <linux/init.h>
13#include <linux/module.h>
14#include <linux/fs.h>
15#include <linux/security.h>
16#include <linux/cred.h>
17#include <linux/eventpoll.h>
18#include <linux/rcupdate.h>
19#include <linux/mount.h>
20#include <linux/capability.h>
21#include <linux/cdev.h>
22#include <linux/fsnotify.h>
23#include <linux/sysctl.h>
24#include <linux/percpu_counter.h>
25#include <linux/percpu.h>
26#include <linux/task_work.h>
27#include <linux/ima.h>
28#include <linux/swap.h>
29
30#include <linux/atomic.h>
31
32#include "internal.h"
33
34
35struct files_stat_struct files_stat = {
36 .max_files = NR_FILE
37};
38
39
40static struct kmem_cache *filp_cachep __read_mostly;
41
42static struct percpu_counter nr_files __cacheline_aligned_in_smp;
43
44static void file_free_rcu(struct rcu_head *head)
45{
46 struct file *f = container_of(head, struct file, f_u.fu_rcuhead);
47
48 put_cred(f->f_cred);
49 kmem_cache_free(filp_cachep, f);
50}
51
52static inline void file_free(struct file *f)
53{
54 percpu_counter_dec(&nr_files);
55 call_rcu(&f->f_u.fu_rcuhead, file_free_rcu);
56}
57
58
59
60
61static long get_nr_files(void)
62{
63 return percpu_counter_read_positive(&nr_files);
64}
65
66
67
68
69unsigned long get_max_files(void)
70{
71 return files_stat.max_files;
72}
73EXPORT_SYMBOL_GPL(get_max_files);
74
75
76
77
78#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
79int proc_nr_files(struct ctl_table *table, int write,
80 void __user *buffer, size_t *lenp, loff_t *ppos)
81{
82 files_stat.nr_files = get_nr_files();
83 return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
84}
85#else
86int proc_nr_files(struct ctl_table *table, int write,
87 void __user *buffer, size_t *lenp, loff_t *ppos)
88{
89 return -ENOSYS;
90}
91#endif
92
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101
102
103struct file *get_empty_filp(void)
104{
105 const struct cred *cred = current_cred();
106 static long old_max;
107 struct file *f;
108 int error;
109
110
111
112
113 if (get_nr_files() >= files_stat.max_files && !capable(CAP_SYS_ADMIN)) {
114
115
116
117
118 if (percpu_counter_sum_positive(&nr_files) >= files_stat.max_files)
119 goto over;
120 }
121
122 f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL);
123 if (unlikely(!f))
124 return ERR_PTR(-ENOMEM);
125
126 percpu_counter_inc(&nr_files);
127 f->f_cred = get_cred(cred);
128 error = security_file_alloc(f);
129 if (unlikely(error)) {
130 file_free(f);
131 return ERR_PTR(error);
132 }
133
134 atomic_long_set(&f->f_count, 1);
135 rwlock_init(&f->f_owner.lock);
136 spin_lock_init(&f->f_lock);
137 mutex_init(&f->f_pos_lock);
138 eventpoll_init_file(f);
139
140 return f;
141
142over:
143
144 if (get_nr_files() > old_max) {
145 pr_info("VFS: file-max limit %lu reached\n", get_max_files());
146 old_max = get_nr_files();
147 }
148 return ERR_PTR(-ENFILE);
149}
150
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156
157
158struct file *alloc_file(const struct path *path, fmode_t mode,
159 const struct file_operations *fop)
160{
161 struct file *file;
162
163 file = get_empty_filp();
164 if (IS_ERR(file))
165 return file;
166
167 file->f_path = *path;
168 file->f_inode = path->dentry->d_inode;
169 file->f_mapping = path->dentry->d_inode->i_mapping;
170 file->f_wb_err = filemap_sample_wb_err(file->f_mapping);
171 if ((mode & FMODE_READ) &&
172 likely(fop->read || fop->read_iter))
173 mode |= FMODE_CAN_READ;
174 if ((mode & FMODE_WRITE) &&
175 likely(fop->write || fop->write_iter))
176 mode |= FMODE_CAN_WRITE;
177 file->f_mode = mode;
178 file->f_op = fop;
179 if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
180 i_readcount_inc(path->dentry->d_inode);
181 return file;
182}
183EXPORT_SYMBOL(alloc_file);
184
185
186
187static void __fput(struct file *file)
188{
189 struct dentry *dentry = file->f_path.dentry;
190 struct vfsmount *mnt = file->f_path.mnt;
191 struct inode *inode = file->f_inode;
192
193 might_sleep();
194
195 fsnotify_close(file);
196
197
198
199
200 eventpoll_release(file);
201 locks_remove_file(file);
202
203 ima_file_free(file);
204 if (unlikely(file->f_flags & FASYNC)) {
205 if (file->f_op->fasync)
206 file->f_op->fasync(-1, file, 0);
207 }
208 if (file->f_op->release)
209 file->f_op->release(inode, file);
210 security_file_free(file);
211 if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL &&
212 !(file->f_mode & FMODE_PATH))) {
213 cdev_put(inode->i_cdev);
214 }
215 fops_put(file->f_op);
216 put_pid(file->f_owner.pid);
217 if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
218 i_readcount_dec(inode);
219 if (file->f_mode & FMODE_WRITER) {
220 put_write_access(inode);
221 __mnt_drop_write(mnt);
222 }
223 file->f_path.dentry = NULL;
224 file->f_path.mnt = NULL;
225 file->f_inode = NULL;
226 file_free(file);
227 dput(dentry);
228 mntput(mnt);
229}
230
231static LLIST_HEAD(delayed_fput_list);
232static void delayed_fput(struct work_struct *unused)
233{
234 struct llist_node *node = llist_del_all(&delayed_fput_list);
235 struct file *f, *t;
236
237 llist_for_each_entry_safe(f, t, node, f_u.fu_llist)
238 __fput(f);
239}
240
241static void ____fput(struct callback_head *work)
242{
243 __fput(container_of(work, struct file, f_u.fu_rcuhead));
244}
245
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255
256void flush_delayed_fput(void)
257{
258 delayed_fput(NULL);
259}
260
261static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput);
262
263void fput(struct file *file)
264{
265 if (atomic_long_dec_and_test(&file->f_count)) {
266 struct task_struct *task = current;
267
268 if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) {
269 init_task_work(&file->f_u.fu_rcuhead, ____fput);
270 if (!task_work_add(task, &file->f_u.fu_rcuhead, true))
271 return;
272
273
274
275
276
277 }
278
279 if (llist_add(&file->f_u.fu_llist, &delayed_fput_list))
280 schedule_delayed_work(&delayed_fput_work, 1);
281 }
282}
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291
292void __fput_sync(struct file *file)
293{
294 if (atomic_long_dec_and_test(&file->f_count)) {
295 struct task_struct *task = current;
296 BUG_ON(!(task->flags & PF_KTHREAD));
297 __fput(file);
298 }
299}
300
301EXPORT_SYMBOL(fput);
302
303void put_filp(struct file *file)
304{
305 if (atomic_long_dec_and_test(&file->f_count)) {
306 security_file_free(file);
307 file_free(file);
308 }
309}
310
311void __init files_init(void)
312{
313 filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0,
314 SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT, NULL);
315 percpu_counter_init(&nr_files, 0, GFP_KERNEL);
316}
317
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321
322void __init files_maxfiles_init(void)
323{
324 unsigned long n;
325 unsigned long memreserve = (totalram_pages - nr_free_pages()) * 3/2;
326
327 memreserve = min(memreserve, totalram_pages - 1);
328 n = ((totalram_pages - memreserve) * (PAGE_SIZE / 1024)) / 10;
329
330 files_stat.max_files = max_t(unsigned long, n, NR_FILE);
331}
332