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TOMOYO Linux Cross Reference
Linux/fs/proc/inode.c

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  1 /*
  2  *  linux/fs/proc/inode.c
  3  *
  4  *  Copyright (C) 1991, 1992  Linus Torvalds
  5  */
  6 
  7 #include <linux/time.h>
  8 #include <linux/proc_fs.h>
  9 #include <linux/kernel.h>
 10 #include <linux/pid_namespace.h>
 11 #include <linux/mm.h>
 12 #include <linux/string.h>
 13 #include <linux/stat.h>
 14 #include <linux/completion.h>
 15 #include <linux/poll.h>
 16 #include <linux/printk.h>
 17 #include <linux/file.h>
 18 #include <linux/limits.h>
 19 #include <linux/init.h>
 20 #include <linux/module.h>
 21 #include <linux/sysctl.h>
 22 #include <linux/seq_file.h>
 23 #include <linux/slab.h>
 24 #include <linux/mount.h>
 25 #include <linux/magic.h>
 26 #include <linux/namei.h>
 27 
 28 #include <asm/uaccess.h>
 29 
 30 #include "internal.h"
 31 
 32 static void proc_evict_inode(struct inode *inode)
 33 {
 34         struct proc_dir_entry *de;
 35         struct ctl_table_header *head;
 36         const struct proc_ns_operations *ns_ops;
 37         void *ns;
 38 
 39         truncate_inode_pages_final(&inode->i_data);
 40         clear_inode(inode);
 41 
 42         /* Stop tracking associated processes */
 43         put_pid(PROC_I(inode)->pid);
 44 
 45         /* Let go of any associated proc directory entry */
 46         de = PROC_I(inode)->pde;
 47         if (de)
 48                 pde_put(de);
 49         head = PROC_I(inode)->sysctl;
 50         if (head) {
 51                 RCU_INIT_POINTER(PROC_I(inode)->sysctl, NULL);
 52                 sysctl_head_put(head);
 53         }
 54         /* Release any associated namespace */
 55         ns_ops = PROC_I(inode)->ns.ns_ops;
 56         ns = PROC_I(inode)->ns.ns;
 57         if (ns_ops && ns)
 58                 ns_ops->put(ns);
 59 }
 60 
 61 static struct kmem_cache * proc_inode_cachep;
 62 
 63 static struct inode *proc_alloc_inode(struct super_block *sb)
 64 {
 65         struct proc_inode *ei;
 66         struct inode *inode;
 67 
 68         ei = (struct proc_inode *)kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL);
 69         if (!ei)
 70                 return NULL;
 71         ei->pid = NULL;
 72         ei->fd = 0;
 73         ei->op.proc_get_link = NULL;
 74         ei->pde = NULL;
 75         ei->sysctl = NULL;
 76         ei->sysctl_entry = NULL;
 77         ei->ns.ns = NULL;
 78         ei->ns.ns_ops = NULL;
 79         inode = &ei->vfs_inode;
 80         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 81         return inode;
 82 }
 83 
 84 static void proc_i_callback(struct rcu_head *head)
 85 {
 86         struct inode *inode = container_of(head, struct inode, i_rcu);
 87         kmem_cache_free(proc_inode_cachep, PROC_I(inode));
 88 }
 89 
 90 static void proc_destroy_inode(struct inode *inode)
 91 {
 92         call_rcu(&inode->i_rcu, proc_i_callback);
 93 }
 94 
 95 static void init_once(void *foo)
 96 {
 97         struct proc_inode *ei = (struct proc_inode *) foo;
 98 
 99         inode_init_once(&ei->vfs_inode);
100 }
101 
102 void __init proc_init_inodecache(void)
103 {
104         proc_inode_cachep = kmem_cache_create("proc_inode_cache",
105                                              sizeof(struct proc_inode),
106                                              0, (SLAB_RECLAIM_ACCOUNT|
107                                                 SLAB_MEM_SPREAD|SLAB_PANIC),
108                                              init_once);
109 }
110 
111 static int proc_show_options(struct seq_file *seq, struct dentry *root)
112 {
113         struct super_block *sb = root->d_sb;
114         struct pid_namespace *pid = sb->s_fs_info;
115 
116         if (!gid_eq(pid->pid_gid, GLOBAL_ROOT_GID))
117                 seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, pid->pid_gid));
118         if (pid->hide_pid != 0)
119                 seq_printf(seq, ",hidepid=%u", pid->hide_pid);
120 
121         return 0;
122 }
123 
124 static const struct super_operations proc_sops = {
125         .alloc_inode    = proc_alloc_inode,
126         .destroy_inode  = proc_destroy_inode,
127         .drop_inode     = generic_delete_inode,
128         .evict_inode    = proc_evict_inode,
129         .statfs         = simple_statfs,
130         .remount_fs     = proc_remount,
131         .show_options   = proc_show_options,
132 };
133 
134 enum {BIAS = -1U<<31};
135 
136 static inline int use_pde(struct proc_dir_entry *pde)
137 {
138         return atomic_inc_unless_negative(&pde->in_use);
139 }
140 
141 static void unuse_pde(struct proc_dir_entry *pde)
142 {
143         if (atomic_dec_return(&pde->in_use) == BIAS)
144                 complete(pde->pde_unload_completion);
145 }
146 
147 /* pde is locked */
148 static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo)
149 {
150         if (pdeo->closing) {
151                 /* somebody else is doing that, just wait */
152                 DECLARE_COMPLETION_ONSTACK(c);
153                 pdeo->c = &c;
154                 spin_unlock(&pde->pde_unload_lock);
155                 wait_for_completion(&c);
156                 spin_lock(&pde->pde_unload_lock);
157         } else {
158                 struct file *file;
159                 pdeo->closing = 1;
160                 spin_unlock(&pde->pde_unload_lock);
161                 file = pdeo->file;
162                 pde->proc_fops->release(file_inode(file), file);
163                 spin_lock(&pde->pde_unload_lock);
164                 list_del_init(&pdeo->lh);
165                 if (pdeo->c)
166                         complete(pdeo->c);
167                 kfree(pdeo);
168         }
169 }
170 
171 void proc_entry_rundown(struct proc_dir_entry *de)
172 {
173         DECLARE_COMPLETION_ONSTACK(c);
174         /* Wait until all existing callers into module are done. */
175         de->pde_unload_completion = &c;
176         if (atomic_add_return(BIAS, &de->in_use) != BIAS)
177                 wait_for_completion(&c);
178 
179         spin_lock(&de->pde_unload_lock);
180         while (!list_empty(&de->pde_openers)) {
181                 struct pde_opener *pdeo;
182                 pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
183                 close_pdeo(de, pdeo);
184         }
185         spin_unlock(&de->pde_unload_lock);
186 }
187 
188 static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
189 {
190         struct proc_dir_entry *pde = PDE(file_inode(file));
191         loff_t rv = -EINVAL;
192         if (use_pde(pde)) {
193                 loff_t (*llseek)(struct file *, loff_t, int);
194                 llseek = pde->proc_fops->llseek;
195                 if (!llseek)
196                         llseek = default_llseek;
197                 rv = llseek(file, offset, whence);
198                 unuse_pde(pde);
199         }
200         return rv;
201 }
202 
203 static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
204 {
205         ssize_t (*read)(struct file *, char __user *, size_t, loff_t *);
206         struct proc_dir_entry *pde = PDE(file_inode(file));
207         ssize_t rv = -EIO;
208         if (use_pde(pde)) {
209                 read = pde->proc_fops->read;
210                 if (read)
211                         rv = read(file, buf, count, ppos);
212                 unuse_pde(pde);
213         }
214         return rv;
215 }
216 
217 static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
218 {
219         ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *);
220         struct proc_dir_entry *pde = PDE(file_inode(file));
221         ssize_t rv = -EIO;
222         if (use_pde(pde)) {
223                 write = pde->proc_fops->write;
224                 if (write)
225                         rv = write(file, buf, count, ppos);
226                 unuse_pde(pde);
227         }
228         return rv;
229 }
230 
231 static unsigned int proc_reg_poll(struct file *file, struct poll_table_struct *pts)
232 {
233         struct proc_dir_entry *pde = PDE(file_inode(file));
234         unsigned int rv = DEFAULT_POLLMASK;
235         unsigned int (*poll)(struct file *, struct poll_table_struct *);
236         if (use_pde(pde)) {
237                 poll = pde->proc_fops->poll;
238                 if (poll)
239                         rv = poll(file, pts);
240                 unuse_pde(pde);
241         }
242         return rv;
243 }
244 
245 static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
246 {
247         struct proc_dir_entry *pde = PDE(file_inode(file));
248         long rv = -ENOTTY;
249         long (*ioctl)(struct file *, unsigned int, unsigned long);
250         if (use_pde(pde)) {
251                 ioctl = pde->proc_fops->unlocked_ioctl;
252                 if (ioctl)
253                         rv = ioctl(file, cmd, arg);
254                 unuse_pde(pde);
255         }
256         return rv;
257 }
258 
259 #ifdef CONFIG_COMPAT
260 static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
261 {
262         struct proc_dir_entry *pde = PDE(file_inode(file));
263         long rv = -ENOTTY;
264         long (*compat_ioctl)(struct file *, unsigned int, unsigned long);
265         if (use_pde(pde)) {
266                 compat_ioctl = pde->proc_fops->compat_ioctl;
267                 if (compat_ioctl)
268                         rv = compat_ioctl(file, cmd, arg);
269                 unuse_pde(pde);
270         }
271         return rv;
272 }
273 #endif
274 
275 static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
276 {
277         struct proc_dir_entry *pde = PDE(file_inode(file));
278         int rv = -EIO;
279         int (*mmap)(struct file *, struct vm_area_struct *);
280         if (use_pde(pde)) {
281                 mmap = pde->proc_fops->mmap;
282                 if (mmap)
283                         rv = mmap(file, vma);
284                 unuse_pde(pde);
285         }
286         return rv;
287 }
288 
289 static unsigned long
290 proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr,
291                            unsigned long len, unsigned long pgoff,
292                            unsigned long flags)
293 {
294         struct proc_dir_entry *pde = PDE(file_inode(file));
295         unsigned long rv = -EIO;
296 
297         if (use_pde(pde)) {
298                 typeof(proc_reg_get_unmapped_area) *get_area;
299 
300                 get_area = pde->proc_fops->get_unmapped_area;
301 #ifdef CONFIG_MMU
302                 if (!get_area)
303                         get_area = current->mm->get_unmapped_area;
304 #endif
305 
306                 if (get_area)
307                         rv = get_area(file, orig_addr, len, pgoff, flags);
308                 else
309                         rv = orig_addr;
310                 unuse_pde(pde);
311         }
312         return rv;
313 }
314 
315 static int proc_reg_open(struct inode *inode, struct file *file)
316 {
317         struct proc_dir_entry *pde = PDE(inode);
318         int rv = 0;
319         int (*open)(struct inode *, struct file *);
320         int (*release)(struct inode *, struct file *);
321         struct pde_opener *pdeo;
322 
323         /*
324          * What for, you ask? Well, we can have open, rmmod, remove_proc_entry
325          * sequence. ->release won't be called because ->proc_fops will be
326          * cleared. Depending on complexity of ->release, consequences vary.
327          *
328          * We can't wait for mercy when close will be done for real, it's
329          * deadlockable: rmmod foo </proc/foo . So, we're going to do ->release
330          * by hand in remove_proc_entry(). For this, save opener's credentials
331          * for later.
332          */
333         pdeo = kzalloc(sizeof(struct pde_opener), GFP_KERNEL);
334         if (!pdeo)
335                 return -ENOMEM;
336 
337         if (!use_pde(pde)) {
338                 kfree(pdeo);
339                 return -ENOENT;
340         }
341         open = pde->proc_fops->open;
342         release = pde->proc_fops->release;
343 
344         if (open)
345                 rv = open(inode, file);
346 
347         if (rv == 0 && release) {
348                 /* To know what to release. */
349                 pdeo->file = file;
350                 /* Strictly for "too late" ->release in proc_reg_release(). */
351                 spin_lock(&pde->pde_unload_lock);
352                 list_add(&pdeo->lh, &pde->pde_openers);
353                 spin_unlock(&pde->pde_unload_lock);
354         } else
355                 kfree(pdeo);
356 
357         unuse_pde(pde);
358         return rv;
359 }
360 
361 static int proc_reg_release(struct inode *inode, struct file *file)
362 {
363         struct proc_dir_entry *pde = PDE(inode);
364         struct pde_opener *pdeo;
365         spin_lock(&pde->pde_unload_lock);
366         list_for_each_entry(pdeo, &pde->pde_openers, lh) {
367                 if (pdeo->file == file) {
368                         close_pdeo(pde, pdeo);
369                         break;
370                 }
371         }
372         spin_unlock(&pde->pde_unload_lock);
373         return 0;
374 }
375 
376 static const struct file_operations proc_reg_file_ops = {
377         .llseek         = proc_reg_llseek,
378         .read           = proc_reg_read,
379         .write          = proc_reg_write,
380         .poll           = proc_reg_poll,
381         .unlocked_ioctl = proc_reg_unlocked_ioctl,
382 #ifdef CONFIG_COMPAT
383         .compat_ioctl   = proc_reg_compat_ioctl,
384 #endif
385         .mmap           = proc_reg_mmap,
386         .get_unmapped_area = proc_reg_get_unmapped_area,
387         .open           = proc_reg_open,
388         .release        = proc_reg_release,
389 };
390 
391 #ifdef CONFIG_COMPAT
392 static const struct file_operations proc_reg_file_ops_no_compat = {
393         .llseek         = proc_reg_llseek,
394         .read           = proc_reg_read,
395         .write          = proc_reg_write,
396         .poll           = proc_reg_poll,
397         .unlocked_ioctl = proc_reg_unlocked_ioctl,
398         .mmap           = proc_reg_mmap,
399         .get_unmapped_area = proc_reg_get_unmapped_area,
400         .open           = proc_reg_open,
401         .release        = proc_reg_release,
402 };
403 #endif
404 
405 static void *proc_follow_link(struct dentry *dentry, struct nameidata *nd)
406 {
407         struct proc_dir_entry *pde = PDE(dentry->d_inode);
408         if (unlikely(!use_pde(pde)))
409                 return ERR_PTR(-EINVAL);
410         nd_set_link(nd, pde->data);
411         return pde;
412 }
413 
414 static void proc_put_link(struct dentry *dentry, struct nameidata *nd, void *p)
415 {
416         unuse_pde(p);
417 }
418 
419 const struct inode_operations proc_link_inode_operations = {
420         .readlink       = generic_readlink,
421         .follow_link    = proc_follow_link,
422         .put_link       = proc_put_link,
423 };
424 
425 struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
426 {
427         struct inode *inode = new_inode_pseudo(sb);
428 
429         if (inode) {
430                 inode->i_ino = de->low_ino;
431                 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
432                 PROC_I(inode)->pde = de;
433 
434                 if (de->mode) {
435                         inode->i_mode = de->mode;
436                         inode->i_uid = de->uid;
437                         inode->i_gid = de->gid;
438                 }
439                 if (de->size)
440                         inode->i_size = de->size;
441                 if (de->nlink)
442                         set_nlink(inode, de->nlink);
443                 WARN_ON(!de->proc_iops);
444                 inode->i_op = de->proc_iops;
445                 if (de->proc_fops) {
446                         if (S_ISREG(inode->i_mode)) {
447 #ifdef CONFIG_COMPAT
448                                 if (!de->proc_fops->compat_ioctl)
449                                         inode->i_fop =
450                                                 &proc_reg_file_ops_no_compat;
451                                 else
452 #endif
453                                         inode->i_fop = &proc_reg_file_ops;
454                         } else {
455                                 inode->i_fop = de->proc_fops;
456                         }
457                 }
458         } else
459                pde_put(de);
460         return inode;
461 }
462 
463 int proc_fill_super(struct super_block *s)
464 {
465         struct inode *root_inode;
466         int ret;
467 
468         s->s_flags |= MS_NODIRATIME | MS_NOSUID | MS_NOEXEC;
469         s->s_blocksize = 1024;
470         s->s_blocksize_bits = 10;
471         s->s_magic = PROC_SUPER_MAGIC;
472         s->s_op = &proc_sops;
473         s->s_time_gran = 1;
474         
475         pde_get(&proc_root);
476         root_inode = proc_get_inode(s, &proc_root);
477         if (!root_inode) {
478                 pr_err("proc_fill_super: get root inode failed\n");
479                 return -ENOMEM;
480         }
481 
482         s->s_root = d_make_root(root_inode);
483         if (!s->s_root) {
484                 pr_err("proc_fill_super: allocate dentry failed\n");
485                 return -ENOMEM;
486         }
487 
488         ret = proc_setup_self(s);
489         if (ret) {
490                 return ret;
491         }
492         return proc_setup_thread_self(s);
493 }
494 

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