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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(&inode->i_data, 0);
 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_assign_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 proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr, unsigned long len, unsigned long pgoff, unsigned long flags)
290 {
291         struct proc_dir_entry *pde = PDE(file_inode(file));
292         unsigned long rv = -EIO;
293         unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long) = NULL;
294         if (use_pde(pde)) {
295 #ifdef CONFIG_MMU
296                 get_unmapped_area = current->mm->get_unmapped_area;
297 #endif
298                 if (pde->proc_fops->get_unmapped_area)
299                         get_unmapped_area = pde->proc_fops->get_unmapped_area;
300                 if (get_unmapped_area)
301                         rv = get_unmapped_area(file, orig_addr, len, pgoff, flags);
302                 unuse_pde(pde);
303         }
304         return rv;
305 }
306 
307 static int proc_reg_open(struct inode *inode, struct file *file)
308 {
309         struct proc_dir_entry *pde = PDE(inode);
310         int rv = 0;
311         int (*open)(struct inode *, struct file *);
312         int (*release)(struct inode *, struct file *);
313         struct pde_opener *pdeo;
314 
315         /*
316          * What for, you ask? Well, we can have open, rmmod, remove_proc_entry
317          * sequence. ->release won't be called because ->proc_fops will be
318          * cleared. Depending on complexity of ->release, consequences vary.
319          *
320          * We can't wait for mercy when close will be done for real, it's
321          * deadlockable: rmmod foo </proc/foo . So, we're going to do ->release
322          * by hand in remove_proc_entry(). For this, save opener's credentials
323          * for later.
324          */
325         pdeo = kzalloc(sizeof(struct pde_opener), GFP_KERNEL);
326         if (!pdeo)
327                 return -ENOMEM;
328 
329         if (!use_pde(pde)) {
330                 kfree(pdeo);
331                 return -ENOENT;
332         }
333         open = pde->proc_fops->open;
334         release = pde->proc_fops->release;
335 
336         if (open)
337                 rv = open(inode, file);
338 
339         if (rv == 0 && release) {
340                 /* To know what to release. */
341                 pdeo->file = file;
342                 /* Strictly for "too late" ->release in proc_reg_release(). */
343                 spin_lock(&pde->pde_unload_lock);
344                 list_add(&pdeo->lh, &pde->pde_openers);
345                 spin_unlock(&pde->pde_unload_lock);
346         } else
347                 kfree(pdeo);
348 
349         unuse_pde(pde);
350         return rv;
351 }
352 
353 static int proc_reg_release(struct inode *inode, struct file *file)
354 {
355         struct proc_dir_entry *pde = PDE(inode);
356         struct pde_opener *pdeo;
357         spin_lock(&pde->pde_unload_lock);
358         list_for_each_entry(pdeo, &pde->pde_openers, lh) {
359                 if (pdeo->file == file) {
360                         close_pdeo(pde, pdeo);
361                         break;
362                 }
363         }
364         spin_unlock(&pde->pde_unload_lock);
365         return 0;
366 }
367 
368 static const struct file_operations proc_reg_file_ops = {
369         .llseek         = proc_reg_llseek,
370         .read           = proc_reg_read,
371         .write          = proc_reg_write,
372         .poll           = proc_reg_poll,
373         .unlocked_ioctl = proc_reg_unlocked_ioctl,
374 #ifdef CONFIG_COMPAT
375         .compat_ioctl   = proc_reg_compat_ioctl,
376 #endif
377         .mmap           = proc_reg_mmap,
378         .get_unmapped_area = proc_reg_get_unmapped_area,
379         .open           = proc_reg_open,
380         .release        = proc_reg_release,
381 };
382 
383 #ifdef CONFIG_COMPAT
384 static const struct file_operations proc_reg_file_ops_no_compat = {
385         .llseek         = proc_reg_llseek,
386         .read           = proc_reg_read,
387         .write          = proc_reg_write,
388         .poll           = proc_reg_poll,
389         .unlocked_ioctl = proc_reg_unlocked_ioctl,
390         .mmap           = proc_reg_mmap,
391         .get_unmapped_area = proc_reg_get_unmapped_area,
392         .open           = proc_reg_open,
393         .release        = proc_reg_release,
394 };
395 #endif
396 
397 static void *proc_follow_link(struct dentry *dentry, struct nameidata *nd)
398 {
399         struct proc_dir_entry *pde = PDE(dentry->d_inode);
400         if (unlikely(!use_pde(pde)))
401                 return ERR_PTR(-EINVAL);
402         nd_set_link(nd, pde->data);
403         return pde;
404 }
405 
406 static void proc_put_link(struct dentry *dentry, struct nameidata *nd, void *p)
407 {
408         unuse_pde(p);
409 }
410 
411 const struct inode_operations proc_link_inode_operations = {
412         .readlink       = generic_readlink,
413         .follow_link    = proc_follow_link,
414         .put_link       = proc_put_link,
415 };
416 
417 struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
418 {
419         struct inode *inode = new_inode_pseudo(sb);
420 
421         if (inode) {
422                 inode->i_ino = de->low_ino;
423                 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
424                 PROC_I(inode)->pde = de;
425 
426                 if (de->mode) {
427                         inode->i_mode = de->mode;
428                         inode->i_uid = de->uid;
429                         inode->i_gid = de->gid;
430                 }
431                 if (de->size)
432                         inode->i_size = de->size;
433                 if (de->nlink)
434                         set_nlink(inode, de->nlink);
435                 WARN_ON(!de->proc_iops);
436                 inode->i_op = de->proc_iops;
437                 if (de->proc_fops) {
438                         if (S_ISREG(inode->i_mode)) {
439 #ifdef CONFIG_COMPAT
440                                 if (!de->proc_fops->compat_ioctl)
441                                         inode->i_fop =
442                                                 &proc_reg_file_ops_no_compat;
443                                 else
444 #endif
445                                         inode->i_fop = &proc_reg_file_ops;
446                         } else {
447                                 inode->i_fop = de->proc_fops;
448                         }
449                 }
450         } else
451                pde_put(de);
452         return inode;
453 }
454 
455 int proc_fill_super(struct super_block *s)
456 {
457         struct inode *root_inode;
458 
459         s->s_flags |= MS_NODIRATIME | MS_NOSUID | MS_NOEXEC;
460         s->s_blocksize = 1024;
461         s->s_blocksize_bits = 10;
462         s->s_magic = PROC_SUPER_MAGIC;
463         s->s_op = &proc_sops;
464         s->s_time_gran = 1;
465         
466         pde_get(&proc_root);
467         root_inode = proc_get_inode(s, &proc_root);
468         if (!root_inode) {
469                 pr_err("proc_fill_super: get root inode failed\n");
470                 return -ENOMEM;
471         }
472 
473         s->s_root = d_make_root(root_inode);
474         if (!s->s_root) {
475                 pr_err("proc_fill_super: allocate dentry failed\n");
476                 return -ENOMEM;
477         }
478 
479         return proc_setup_self(s);
480 }
481 

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