xref: /openbmc/linux/fs/proc/base.c (revision b6dcefde)
1 /*
2  *  linux/fs/proc/base.c
3  *
4  *  Copyright (C) 1991, 1992 Linus Torvalds
5  *
6  *  proc base directory handling functions
7  *
8  *  1999, Al Viro. Rewritten. Now it covers the whole per-process part.
9  *  Instead of using magical inumbers to determine the kind of object
10  *  we allocate and fill in-core inodes upon lookup. They don't even
11  *  go into icache. We cache the reference to task_struct upon lookup too.
12  *  Eventually it should become a filesystem in its own. We don't use the
13  *  rest of procfs anymore.
14  *
15  *
16  *  Changelog:
17  *  17-Jan-2005
18  *  Allan Bezerra
19  *  Bruna Moreira <bruna.moreira@indt.org.br>
20  *  Edjard Mota <edjard.mota@indt.org.br>
21  *  Ilias Biris <ilias.biris@indt.org.br>
22  *  Mauricio Lin <mauricio.lin@indt.org.br>
23  *
24  *  Embedded Linux Lab - 10LE Instituto Nokia de Tecnologia - INdT
25  *
26  *  A new process specific entry (smaps) included in /proc. It shows the
27  *  size of rss for each memory area. The maps entry lacks information
28  *  about physical memory size (rss) for each mapped file, i.e.,
29  *  rss information for executables and library files.
30  *  This additional information is useful for any tools that need to know
31  *  about physical memory consumption for a process specific library.
32  *
33  *  Changelog:
34  *  21-Feb-2005
35  *  Embedded Linux Lab - 10LE Instituto Nokia de Tecnologia - INdT
36  *  Pud inclusion in the page table walking.
37  *
38  *  ChangeLog:
39  *  10-Mar-2005
40  *  10LE Instituto Nokia de Tecnologia - INdT:
41  *  A better way to walks through the page table as suggested by Hugh Dickins.
42  *
43  *  Simo Piiroinen <simo.piiroinen@nokia.com>:
44  *  Smaps information related to shared, private, clean and dirty pages.
45  *
46  *  Paul Mundt <paul.mundt@nokia.com>:
47  *  Overall revision about smaps.
48  */
49 
50 #include <asm/uaccess.h>
51 
52 #include <linux/errno.h>
53 #include <linux/time.h>
54 #include <linux/proc_fs.h>
55 #include <linux/stat.h>
56 #include <linux/task_io_accounting_ops.h>
57 #include <linux/init.h>
58 #include <linux/capability.h>
59 #include <linux/file.h>
60 #include <linux/fdtable.h>
61 #include <linux/string.h>
62 #include <linux/seq_file.h>
63 #include <linux/namei.h>
64 #include <linux/mnt_namespace.h>
65 #include <linux/mm.h>
66 #include <linux/rcupdate.h>
67 #include <linux/kallsyms.h>
68 #include <linux/stacktrace.h>
69 #include <linux/resource.h>
70 #include <linux/module.h>
71 #include <linux/mount.h>
72 #include <linux/security.h>
73 #include <linux/ptrace.h>
74 #include <linux/tracehook.h>
75 #include <linux/cgroup.h>
76 #include <linux/cpuset.h>
77 #include <linux/audit.h>
78 #include <linux/poll.h>
79 #include <linux/nsproxy.h>
80 #include <linux/oom.h>
81 #include <linux/elf.h>
82 #include <linux/pid_namespace.h>
83 #include <linux/fs_struct.h>
84 #include "internal.h"
85 
86 /* NOTE:
87  *	Implementing inode permission operations in /proc is almost
88  *	certainly an error.  Permission checks need to happen during
89  *	each system call not at open time.  The reason is that most of
90  *	what we wish to check for permissions in /proc varies at runtime.
91  *
92  *	The classic example of a problem is opening file descriptors
93  *	in /proc for a task before it execs a suid executable.
94  */
95 
96 struct pid_entry {
97 	char *name;
98 	int len;
99 	mode_t mode;
100 	const struct inode_operations *iop;
101 	const struct file_operations *fop;
102 	union proc_op op;
103 };
104 
105 #define NOD(NAME, MODE, IOP, FOP, OP) {			\
106 	.name = (NAME),					\
107 	.len  = sizeof(NAME) - 1,			\
108 	.mode = MODE,					\
109 	.iop  = IOP,					\
110 	.fop  = FOP,					\
111 	.op   = OP,					\
112 }
113 
114 #define DIR(NAME, MODE, iops, fops)	\
115 	NOD(NAME, (S_IFDIR|(MODE)), &iops, &fops, {} )
116 #define LNK(NAME, get_link)					\
117 	NOD(NAME, (S_IFLNK|S_IRWXUGO),				\
118 		&proc_pid_link_inode_operations, NULL,		\
119 		{ .proc_get_link = get_link } )
120 #define REG(NAME, MODE, fops)				\
121 	NOD(NAME, (S_IFREG|(MODE)), NULL, &fops, {})
122 #define INF(NAME, MODE, read)				\
123 	NOD(NAME, (S_IFREG|(MODE)), 			\
124 		NULL, &proc_info_file_operations,	\
125 		{ .proc_read = read } )
126 #define ONE(NAME, MODE, show)				\
127 	NOD(NAME, (S_IFREG|(MODE)), 			\
128 		NULL, &proc_single_file_operations,	\
129 		{ .proc_show = show } )
130 
131 /*
132  * Count the number of hardlinks for the pid_entry table, excluding the .
133  * and .. links.
134  */
135 static unsigned int pid_entry_count_dirs(const struct pid_entry *entries,
136 	unsigned int n)
137 {
138 	unsigned int i;
139 	unsigned int count;
140 
141 	count = 0;
142 	for (i = 0; i < n; ++i) {
143 		if (S_ISDIR(entries[i].mode))
144 			++count;
145 	}
146 
147 	return count;
148 }
149 
150 static int get_fs_path(struct task_struct *task, struct path *path, bool root)
151 {
152 	struct fs_struct *fs;
153 	int result = -ENOENT;
154 
155 	task_lock(task);
156 	fs = task->fs;
157 	if (fs) {
158 		read_lock(&fs->lock);
159 		*path = root ? fs->root : fs->pwd;
160 		path_get(path);
161 		read_unlock(&fs->lock);
162 		result = 0;
163 	}
164 	task_unlock(task);
165 	return result;
166 }
167 
168 static int get_nr_threads(struct task_struct *tsk)
169 {
170 	unsigned long flags;
171 	int count = 0;
172 
173 	if (lock_task_sighand(tsk, &flags)) {
174 		count = atomic_read(&tsk->signal->count);
175 		unlock_task_sighand(tsk, &flags);
176 	}
177 	return count;
178 }
179 
180 static int proc_cwd_link(struct inode *inode, struct path *path)
181 {
182 	struct task_struct *task = get_proc_task(inode);
183 	int result = -ENOENT;
184 
185 	if (task) {
186 		result = get_fs_path(task, path, 0);
187 		put_task_struct(task);
188 	}
189 	return result;
190 }
191 
192 static int proc_root_link(struct inode *inode, struct path *path)
193 {
194 	struct task_struct *task = get_proc_task(inode);
195 	int result = -ENOENT;
196 
197 	if (task) {
198 		result = get_fs_path(task, path, 1);
199 		put_task_struct(task);
200 	}
201 	return result;
202 }
203 
204 /*
205  * Return zero if current may access user memory in @task, -error if not.
206  */
207 static int check_mem_permission(struct task_struct *task)
208 {
209 	/*
210 	 * A task can always look at itself, in case it chooses
211 	 * to use system calls instead of load instructions.
212 	 */
213 	if (task == current)
214 		return 0;
215 
216 	/*
217 	 * If current is actively ptrace'ing, and would also be
218 	 * permitted to freshly attach with ptrace now, permit it.
219 	 */
220 	if (task_is_stopped_or_traced(task)) {
221 		int match;
222 		rcu_read_lock();
223 		match = (tracehook_tracer_task(task) == current);
224 		rcu_read_unlock();
225 		if (match && ptrace_may_access(task, PTRACE_MODE_ATTACH))
226 			return 0;
227 	}
228 
229 	/*
230 	 * Noone else is allowed.
231 	 */
232 	return -EPERM;
233 }
234 
235 struct mm_struct *mm_for_maps(struct task_struct *task)
236 {
237 	struct mm_struct *mm;
238 
239 	if (mutex_lock_killable(&task->cred_guard_mutex))
240 		return NULL;
241 
242 	mm = get_task_mm(task);
243 	if (mm && mm != current->mm &&
244 			!ptrace_may_access(task, PTRACE_MODE_READ)) {
245 		mmput(mm);
246 		mm = NULL;
247 	}
248 	mutex_unlock(&task->cred_guard_mutex);
249 
250 	return mm;
251 }
252 
253 static int proc_pid_cmdline(struct task_struct *task, char * buffer)
254 {
255 	int res = 0;
256 	unsigned int len;
257 	struct mm_struct *mm = get_task_mm(task);
258 	if (!mm)
259 		goto out;
260 	if (!mm->arg_end)
261 		goto out_mm;	/* Shh! No looking before we're done */
262 
263  	len = mm->arg_end - mm->arg_start;
264 
265 	if (len > PAGE_SIZE)
266 		len = PAGE_SIZE;
267 
268 	res = access_process_vm(task, mm->arg_start, buffer, len, 0);
269 
270 	// If the nul at the end of args has been overwritten, then
271 	// assume application is using setproctitle(3).
272 	if (res > 0 && buffer[res-1] != '\0' && len < PAGE_SIZE) {
273 		len = strnlen(buffer, res);
274 		if (len < res) {
275 		    res = len;
276 		} else {
277 			len = mm->env_end - mm->env_start;
278 			if (len > PAGE_SIZE - res)
279 				len = PAGE_SIZE - res;
280 			res += access_process_vm(task, mm->env_start, buffer+res, len, 0);
281 			res = strnlen(buffer, res);
282 		}
283 	}
284 out_mm:
285 	mmput(mm);
286 out:
287 	return res;
288 }
289 
290 static int proc_pid_auxv(struct task_struct *task, char *buffer)
291 {
292 	int res = 0;
293 	struct mm_struct *mm = get_task_mm(task);
294 	if (mm) {
295 		unsigned int nwords = 0;
296 		do {
297 			nwords += 2;
298 		} while (mm->saved_auxv[nwords - 2] != 0); /* AT_NULL */
299 		res = nwords * sizeof(mm->saved_auxv[0]);
300 		if (res > PAGE_SIZE)
301 			res = PAGE_SIZE;
302 		memcpy(buffer, mm->saved_auxv, res);
303 		mmput(mm);
304 	}
305 	return res;
306 }
307 
308 
309 #ifdef CONFIG_KALLSYMS
310 /*
311  * Provides a wchan file via kallsyms in a proper one-value-per-file format.
312  * Returns the resolved symbol.  If that fails, simply return the address.
313  */
314 static int proc_pid_wchan(struct task_struct *task, char *buffer)
315 {
316 	unsigned long wchan;
317 	char symname[KSYM_NAME_LEN];
318 
319 	wchan = get_wchan(task);
320 
321 	if (lookup_symbol_name(wchan, symname) < 0)
322 		if (!ptrace_may_access(task, PTRACE_MODE_READ))
323 			return 0;
324 		else
325 			return sprintf(buffer, "%lu", wchan);
326 	else
327 		return sprintf(buffer, "%s", symname);
328 }
329 #endif /* CONFIG_KALLSYMS */
330 
331 #ifdef CONFIG_STACKTRACE
332 
333 #define MAX_STACK_TRACE_DEPTH	64
334 
335 static int proc_pid_stack(struct seq_file *m, struct pid_namespace *ns,
336 			  struct pid *pid, struct task_struct *task)
337 {
338 	struct stack_trace trace;
339 	unsigned long *entries;
340 	int i;
341 
342 	entries = kmalloc(MAX_STACK_TRACE_DEPTH * sizeof(*entries), GFP_KERNEL);
343 	if (!entries)
344 		return -ENOMEM;
345 
346 	trace.nr_entries	= 0;
347 	trace.max_entries	= MAX_STACK_TRACE_DEPTH;
348 	trace.entries		= entries;
349 	trace.skip		= 0;
350 	save_stack_trace_tsk(task, &trace);
351 
352 	for (i = 0; i < trace.nr_entries; i++) {
353 		seq_printf(m, "[<%p>] %pS\n",
354 			   (void *)entries[i], (void *)entries[i]);
355 	}
356 	kfree(entries);
357 
358 	return 0;
359 }
360 #endif
361 
362 #ifdef CONFIG_SCHEDSTATS
363 /*
364  * Provides /proc/PID/schedstat
365  */
366 static int proc_pid_schedstat(struct task_struct *task, char *buffer)
367 {
368 	return sprintf(buffer, "%llu %llu %lu\n",
369 			(unsigned long long)task->se.sum_exec_runtime,
370 			(unsigned long long)task->sched_info.run_delay,
371 			task->sched_info.pcount);
372 }
373 #endif
374 
375 #ifdef CONFIG_LATENCYTOP
376 static int lstats_show_proc(struct seq_file *m, void *v)
377 {
378 	int i;
379 	struct inode *inode = m->private;
380 	struct task_struct *task = get_proc_task(inode);
381 
382 	if (!task)
383 		return -ESRCH;
384 	seq_puts(m, "Latency Top version : v0.1\n");
385 	for (i = 0; i < 32; i++) {
386 		if (task->latency_record[i].backtrace[0]) {
387 			int q;
388 			seq_printf(m, "%i %li %li ",
389 				task->latency_record[i].count,
390 				task->latency_record[i].time,
391 				task->latency_record[i].max);
392 			for (q = 0; q < LT_BACKTRACEDEPTH; q++) {
393 				char sym[KSYM_SYMBOL_LEN];
394 				char *c;
395 				if (!task->latency_record[i].backtrace[q])
396 					break;
397 				if (task->latency_record[i].backtrace[q] == ULONG_MAX)
398 					break;
399 				sprint_symbol(sym, task->latency_record[i].backtrace[q]);
400 				c = strchr(sym, '+');
401 				if (c)
402 					*c = 0;
403 				seq_printf(m, "%s ", sym);
404 			}
405 			seq_printf(m, "\n");
406 		}
407 
408 	}
409 	put_task_struct(task);
410 	return 0;
411 }
412 
413 static int lstats_open(struct inode *inode, struct file *file)
414 {
415 	return single_open(file, lstats_show_proc, inode);
416 }
417 
418 static ssize_t lstats_write(struct file *file, const char __user *buf,
419 			    size_t count, loff_t *offs)
420 {
421 	struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
422 
423 	if (!task)
424 		return -ESRCH;
425 	clear_all_latency_tracing(task);
426 	put_task_struct(task);
427 
428 	return count;
429 }
430 
431 static const struct file_operations proc_lstats_operations = {
432 	.open		= lstats_open,
433 	.read		= seq_read,
434 	.write		= lstats_write,
435 	.llseek		= seq_lseek,
436 	.release	= single_release,
437 };
438 
439 #endif
440 
441 /* The badness from the OOM killer */
442 unsigned long badness(struct task_struct *p, unsigned long uptime);
443 static int proc_oom_score(struct task_struct *task, char *buffer)
444 {
445 	unsigned long points;
446 	struct timespec uptime;
447 
448 	do_posix_clock_monotonic_gettime(&uptime);
449 	read_lock(&tasklist_lock);
450 	points = badness(task->group_leader, uptime.tv_sec);
451 	read_unlock(&tasklist_lock);
452 	return sprintf(buffer, "%lu\n", points);
453 }
454 
455 struct limit_names {
456 	char *name;
457 	char *unit;
458 };
459 
460 static const struct limit_names lnames[RLIM_NLIMITS] = {
461 	[RLIMIT_CPU] = {"Max cpu time", "seconds"},
462 	[RLIMIT_FSIZE] = {"Max file size", "bytes"},
463 	[RLIMIT_DATA] = {"Max data size", "bytes"},
464 	[RLIMIT_STACK] = {"Max stack size", "bytes"},
465 	[RLIMIT_CORE] = {"Max core file size", "bytes"},
466 	[RLIMIT_RSS] = {"Max resident set", "bytes"},
467 	[RLIMIT_NPROC] = {"Max processes", "processes"},
468 	[RLIMIT_NOFILE] = {"Max open files", "files"},
469 	[RLIMIT_MEMLOCK] = {"Max locked memory", "bytes"},
470 	[RLIMIT_AS] = {"Max address space", "bytes"},
471 	[RLIMIT_LOCKS] = {"Max file locks", "locks"},
472 	[RLIMIT_SIGPENDING] = {"Max pending signals", "signals"},
473 	[RLIMIT_MSGQUEUE] = {"Max msgqueue size", "bytes"},
474 	[RLIMIT_NICE] = {"Max nice priority", NULL},
475 	[RLIMIT_RTPRIO] = {"Max realtime priority", NULL},
476 	[RLIMIT_RTTIME] = {"Max realtime timeout", "us"},
477 };
478 
479 /* Display limits for a process */
480 static int proc_pid_limits(struct task_struct *task, char *buffer)
481 {
482 	unsigned int i;
483 	int count = 0;
484 	unsigned long flags;
485 	char *bufptr = buffer;
486 
487 	struct rlimit rlim[RLIM_NLIMITS];
488 
489 	if (!lock_task_sighand(task, &flags))
490 		return 0;
491 	memcpy(rlim, task->signal->rlim, sizeof(struct rlimit) * RLIM_NLIMITS);
492 	unlock_task_sighand(task, &flags);
493 
494 	/*
495 	 * print the file header
496 	 */
497 	count += sprintf(&bufptr[count], "%-25s %-20s %-20s %-10s\n",
498 			"Limit", "Soft Limit", "Hard Limit", "Units");
499 
500 	for (i = 0; i < RLIM_NLIMITS; i++) {
501 		if (rlim[i].rlim_cur == RLIM_INFINITY)
502 			count += sprintf(&bufptr[count], "%-25s %-20s ",
503 					 lnames[i].name, "unlimited");
504 		else
505 			count += sprintf(&bufptr[count], "%-25s %-20lu ",
506 					 lnames[i].name, rlim[i].rlim_cur);
507 
508 		if (rlim[i].rlim_max == RLIM_INFINITY)
509 			count += sprintf(&bufptr[count], "%-20s ", "unlimited");
510 		else
511 			count += sprintf(&bufptr[count], "%-20lu ",
512 					 rlim[i].rlim_max);
513 
514 		if (lnames[i].unit)
515 			count += sprintf(&bufptr[count], "%-10s\n",
516 					 lnames[i].unit);
517 		else
518 			count += sprintf(&bufptr[count], "\n");
519 	}
520 
521 	return count;
522 }
523 
524 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
525 static int proc_pid_syscall(struct task_struct *task, char *buffer)
526 {
527 	long nr;
528 	unsigned long args[6], sp, pc;
529 
530 	if (task_current_syscall(task, &nr, args, 6, &sp, &pc))
531 		return sprintf(buffer, "running\n");
532 
533 	if (nr < 0)
534 		return sprintf(buffer, "%ld 0x%lx 0x%lx\n", nr, sp, pc);
535 
536 	return sprintf(buffer,
537 		       "%ld 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx\n",
538 		       nr,
539 		       args[0], args[1], args[2], args[3], args[4], args[5],
540 		       sp, pc);
541 }
542 #endif /* CONFIG_HAVE_ARCH_TRACEHOOK */
543 
544 /************************************************************************/
545 /*                       Here the fs part begins                        */
546 /************************************************************************/
547 
548 /* permission checks */
549 static int proc_fd_access_allowed(struct inode *inode)
550 {
551 	struct task_struct *task;
552 	int allowed = 0;
553 	/* Allow access to a task's file descriptors if it is us or we
554 	 * may use ptrace attach to the process and find out that
555 	 * information.
556 	 */
557 	task = get_proc_task(inode);
558 	if (task) {
559 		allowed = ptrace_may_access(task, PTRACE_MODE_READ);
560 		put_task_struct(task);
561 	}
562 	return allowed;
563 }
564 
565 static int proc_setattr(struct dentry *dentry, struct iattr *attr)
566 {
567 	int error;
568 	struct inode *inode = dentry->d_inode;
569 
570 	if (attr->ia_valid & ATTR_MODE)
571 		return -EPERM;
572 
573 	error = inode_change_ok(inode, attr);
574 	if (!error)
575 		error = inode_setattr(inode, attr);
576 	return error;
577 }
578 
579 static const struct inode_operations proc_def_inode_operations = {
580 	.setattr	= proc_setattr,
581 };
582 
583 static int mounts_open_common(struct inode *inode, struct file *file,
584 			      const struct seq_operations *op)
585 {
586 	struct task_struct *task = get_proc_task(inode);
587 	struct nsproxy *nsp;
588 	struct mnt_namespace *ns = NULL;
589 	struct path root;
590 	struct proc_mounts *p;
591 	int ret = -EINVAL;
592 
593 	if (task) {
594 		rcu_read_lock();
595 		nsp = task_nsproxy(task);
596 		if (nsp) {
597 			ns = nsp->mnt_ns;
598 			if (ns)
599 				get_mnt_ns(ns);
600 		}
601 		rcu_read_unlock();
602 		if (ns && get_fs_path(task, &root, 1) == 0)
603 			ret = 0;
604 		put_task_struct(task);
605 	}
606 
607 	if (!ns)
608 		goto err;
609 	if (ret)
610 		goto err_put_ns;
611 
612 	ret = -ENOMEM;
613 	p = kmalloc(sizeof(struct proc_mounts), GFP_KERNEL);
614 	if (!p)
615 		goto err_put_path;
616 
617 	file->private_data = &p->m;
618 	ret = seq_open(file, op);
619 	if (ret)
620 		goto err_free;
621 
622 	p->m.private = p;
623 	p->ns = ns;
624 	p->root = root;
625 	p->event = ns->event;
626 
627 	return 0;
628 
629  err_free:
630 	kfree(p);
631  err_put_path:
632 	path_put(&root);
633  err_put_ns:
634 	put_mnt_ns(ns);
635  err:
636 	return ret;
637 }
638 
639 static int mounts_release(struct inode *inode, struct file *file)
640 {
641 	struct proc_mounts *p = file->private_data;
642 	path_put(&p->root);
643 	put_mnt_ns(p->ns);
644 	return seq_release(inode, file);
645 }
646 
647 static unsigned mounts_poll(struct file *file, poll_table *wait)
648 {
649 	struct proc_mounts *p = file->private_data;
650 	struct mnt_namespace *ns = p->ns;
651 	unsigned res = POLLIN | POLLRDNORM;
652 
653 	poll_wait(file, &ns->poll, wait);
654 
655 	spin_lock(&vfsmount_lock);
656 	if (p->event != ns->event) {
657 		p->event = ns->event;
658 		res |= POLLERR | POLLPRI;
659 	}
660 	spin_unlock(&vfsmount_lock);
661 
662 	return res;
663 }
664 
665 static int mounts_open(struct inode *inode, struct file *file)
666 {
667 	return mounts_open_common(inode, file, &mounts_op);
668 }
669 
670 static const struct file_operations proc_mounts_operations = {
671 	.open		= mounts_open,
672 	.read		= seq_read,
673 	.llseek		= seq_lseek,
674 	.release	= mounts_release,
675 	.poll		= mounts_poll,
676 };
677 
678 static int mountinfo_open(struct inode *inode, struct file *file)
679 {
680 	return mounts_open_common(inode, file, &mountinfo_op);
681 }
682 
683 static const struct file_operations proc_mountinfo_operations = {
684 	.open		= mountinfo_open,
685 	.read		= seq_read,
686 	.llseek		= seq_lseek,
687 	.release	= mounts_release,
688 	.poll		= mounts_poll,
689 };
690 
691 static int mountstats_open(struct inode *inode, struct file *file)
692 {
693 	return mounts_open_common(inode, file, &mountstats_op);
694 }
695 
696 static const struct file_operations proc_mountstats_operations = {
697 	.open		= mountstats_open,
698 	.read		= seq_read,
699 	.llseek		= seq_lseek,
700 	.release	= mounts_release,
701 };
702 
703 #define PROC_BLOCK_SIZE	(3*1024)		/* 4K page size but our output routines use some slack for overruns */
704 
705 static ssize_t proc_info_read(struct file * file, char __user * buf,
706 			  size_t count, loff_t *ppos)
707 {
708 	struct inode * inode = file->f_path.dentry->d_inode;
709 	unsigned long page;
710 	ssize_t length;
711 	struct task_struct *task = get_proc_task(inode);
712 
713 	length = -ESRCH;
714 	if (!task)
715 		goto out_no_task;
716 
717 	if (count > PROC_BLOCK_SIZE)
718 		count = PROC_BLOCK_SIZE;
719 
720 	length = -ENOMEM;
721 	if (!(page = __get_free_page(GFP_TEMPORARY)))
722 		goto out;
723 
724 	length = PROC_I(inode)->op.proc_read(task, (char*)page);
725 
726 	if (length >= 0)
727 		length = simple_read_from_buffer(buf, count, ppos, (char *)page, length);
728 	free_page(page);
729 out:
730 	put_task_struct(task);
731 out_no_task:
732 	return length;
733 }
734 
735 static const struct file_operations proc_info_file_operations = {
736 	.read		= proc_info_read,
737 };
738 
739 static int proc_single_show(struct seq_file *m, void *v)
740 {
741 	struct inode *inode = m->private;
742 	struct pid_namespace *ns;
743 	struct pid *pid;
744 	struct task_struct *task;
745 	int ret;
746 
747 	ns = inode->i_sb->s_fs_info;
748 	pid = proc_pid(inode);
749 	task = get_pid_task(pid, PIDTYPE_PID);
750 	if (!task)
751 		return -ESRCH;
752 
753 	ret = PROC_I(inode)->op.proc_show(m, ns, pid, task);
754 
755 	put_task_struct(task);
756 	return ret;
757 }
758 
759 static int proc_single_open(struct inode *inode, struct file *filp)
760 {
761 	int ret;
762 	ret = single_open(filp, proc_single_show, NULL);
763 	if (!ret) {
764 		struct seq_file *m = filp->private_data;
765 
766 		m->private = inode;
767 	}
768 	return ret;
769 }
770 
771 static const struct file_operations proc_single_file_operations = {
772 	.open		= proc_single_open,
773 	.read		= seq_read,
774 	.llseek		= seq_lseek,
775 	.release	= single_release,
776 };
777 
778 static int mem_open(struct inode* inode, struct file* file)
779 {
780 	file->private_data = (void*)((long)current->self_exec_id);
781 	return 0;
782 }
783 
784 static ssize_t mem_read(struct file * file, char __user * buf,
785 			size_t count, loff_t *ppos)
786 {
787 	struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
788 	char *page;
789 	unsigned long src = *ppos;
790 	int ret = -ESRCH;
791 	struct mm_struct *mm;
792 
793 	if (!task)
794 		goto out_no_task;
795 
796 	if (check_mem_permission(task))
797 		goto out;
798 
799 	ret = -ENOMEM;
800 	page = (char *)__get_free_page(GFP_TEMPORARY);
801 	if (!page)
802 		goto out;
803 
804 	ret = 0;
805 
806 	mm = get_task_mm(task);
807 	if (!mm)
808 		goto out_free;
809 
810 	ret = -EIO;
811 
812 	if (file->private_data != (void*)((long)current->self_exec_id))
813 		goto out_put;
814 
815 	ret = 0;
816 
817 	while (count > 0) {
818 		int this_len, retval;
819 
820 		this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
821 		retval = access_process_vm(task, src, page, this_len, 0);
822 		if (!retval || check_mem_permission(task)) {
823 			if (!ret)
824 				ret = -EIO;
825 			break;
826 		}
827 
828 		if (copy_to_user(buf, page, retval)) {
829 			ret = -EFAULT;
830 			break;
831 		}
832 
833 		ret += retval;
834 		src += retval;
835 		buf += retval;
836 		count -= retval;
837 	}
838 	*ppos = src;
839 
840 out_put:
841 	mmput(mm);
842 out_free:
843 	free_page((unsigned long) page);
844 out:
845 	put_task_struct(task);
846 out_no_task:
847 	return ret;
848 }
849 
850 #define mem_write NULL
851 
852 #ifndef mem_write
853 /* This is a security hazard */
854 static ssize_t mem_write(struct file * file, const char __user *buf,
855 			 size_t count, loff_t *ppos)
856 {
857 	int copied;
858 	char *page;
859 	struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
860 	unsigned long dst = *ppos;
861 
862 	copied = -ESRCH;
863 	if (!task)
864 		goto out_no_task;
865 
866 	if (check_mem_permission(task))
867 		goto out;
868 
869 	copied = -ENOMEM;
870 	page = (char *)__get_free_page(GFP_TEMPORARY);
871 	if (!page)
872 		goto out;
873 
874 	copied = 0;
875 	while (count > 0) {
876 		int this_len, retval;
877 
878 		this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
879 		if (copy_from_user(page, buf, this_len)) {
880 			copied = -EFAULT;
881 			break;
882 		}
883 		retval = access_process_vm(task, dst, page, this_len, 1);
884 		if (!retval) {
885 			if (!copied)
886 				copied = -EIO;
887 			break;
888 		}
889 		copied += retval;
890 		buf += retval;
891 		dst += retval;
892 		count -= retval;
893 	}
894 	*ppos = dst;
895 	free_page((unsigned long) page);
896 out:
897 	put_task_struct(task);
898 out_no_task:
899 	return copied;
900 }
901 #endif
902 
903 loff_t mem_lseek(struct file *file, loff_t offset, int orig)
904 {
905 	switch (orig) {
906 	case 0:
907 		file->f_pos = offset;
908 		break;
909 	case 1:
910 		file->f_pos += offset;
911 		break;
912 	default:
913 		return -EINVAL;
914 	}
915 	force_successful_syscall_return();
916 	return file->f_pos;
917 }
918 
919 static const struct file_operations proc_mem_operations = {
920 	.llseek		= mem_lseek,
921 	.read		= mem_read,
922 	.write		= mem_write,
923 	.open		= mem_open,
924 };
925 
926 static ssize_t environ_read(struct file *file, char __user *buf,
927 			size_t count, loff_t *ppos)
928 {
929 	struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
930 	char *page;
931 	unsigned long src = *ppos;
932 	int ret = -ESRCH;
933 	struct mm_struct *mm;
934 
935 	if (!task)
936 		goto out_no_task;
937 
938 	if (!ptrace_may_access(task, PTRACE_MODE_READ))
939 		goto out;
940 
941 	ret = -ENOMEM;
942 	page = (char *)__get_free_page(GFP_TEMPORARY);
943 	if (!page)
944 		goto out;
945 
946 	ret = 0;
947 
948 	mm = get_task_mm(task);
949 	if (!mm)
950 		goto out_free;
951 
952 	while (count > 0) {
953 		int this_len, retval, max_len;
954 
955 		this_len = mm->env_end - (mm->env_start + src);
956 
957 		if (this_len <= 0)
958 			break;
959 
960 		max_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
961 		this_len = (this_len > max_len) ? max_len : this_len;
962 
963 		retval = access_process_vm(task, (mm->env_start + src),
964 			page, this_len, 0);
965 
966 		if (retval <= 0) {
967 			ret = retval;
968 			break;
969 		}
970 
971 		if (copy_to_user(buf, page, retval)) {
972 			ret = -EFAULT;
973 			break;
974 		}
975 
976 		ret += retval;
977 		src += retval;
978 		buf += retval;
979 		count -= retval;
980 	}
981 	*ppos = src;
982 
983 	mmput(mm);
984 out_free:
985 	free_page((unsigned long) page);
986 out:
987 	put_task_struct(task);
988 out_no_task:
989 	return ret;
990 }
991 
992 static const struct file_operations proc_environ_operations = {
993 	.read		= environ_read,
994 };
995 
996 static ssize_t oom_adjust_read(struct file *file, char __user *buf,
997 				size_t count, loff_t *ppos)
998 {
999 	struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
1000 	char buffer[PROC_NUMBUF];
1001 	size_t len;
1002 	int oom_adjust = OOM_DISABLE;
1003 	unsigned long flags;
1004 
1005 	if (!task)
1006 		return -ESRCH;
1007 
1008 	if (lock_task_sighand(task, &flags)) {
1009 		oom_adjust = task->signal->oom_adj;
1010 		unlock_task_sighand(task, &flags);
1011 	}
1012 
1013 	put_task_struct(task);
1014 
1015 	len = snprintf(buffer, sizeof(buffer), "%i\n", oom_adjust);
1016 
1017 	return simple_read_from_buffer(buf, count, ppos, buffer, len);
1018 }
1019 
1020 static ssize_t oom_adjust_write(struct file *file, const char __user *buf,
1021 				size_t count, loff_t *ppos)
1022 {
1023 	struct task_struct *task;
1024 	char buffer[PROC_NUMBUF];
1025 	long oom_adjust;
1026 	unsigned long flags;
1027 	int err;
1028 
1029 	memset(buffer, 0, sizeof(buffer));
1030 	if (count > sizeof(buffer) - 1)
1031 		count = sizeof(buffer) - 1;
1032 	if (copy_from_user(buffer, buf, count))
1033 		return -EFAULT;
1034 
1035 	err = strict_strtol(strstrip(buffer), 0, &oom_adjust);
1036 	if (err)
1037 		return -EINVAL;
1038 	if ((oom_adjust < OOM_ADJUST_MIN || oom_adjust > OOM_ADJUST_MAX) &&
1039 	     oom_adjust != OOM_DISABLE)
1040 		return -EINVAL;
1041 
1042 	task = get_proc_task(file->f_path.dentry->d_inode);
1043 	if (!task)
1044 		return -ESRCH;
1045 	if (!lock_task_sighand(task, &flags)) {
1046 		put_task_struct(task);
1047 		return -ESRCH;
1048 	}
1049 
1050 	if (oom_adjust < task->signal->oom_adj && !capable(CAP_SYS_RESOURCE)) {
1051 		unlock_task_sighand(task, &flags);
1052 		put_task_struct(task);
1053 		return -EACCES;
1054 	}
1055 
1056 	task->signal->oom_adj = oom_adjust;
1057 
1058 	unlock_task_sighand(task, &flags);
1059 	put_task_struct(task);
1060 
1061 	return count;
1062 }
1063 
1064 static const struct file_operations proc_oom_adjust_operations = {
1065 	.read		= oom_adjust_read,
1066 	.write		= oom_adjust_write,
1067 };
1068 
1069 #ifdef CONFIG_AUDITSYSCALL
1070 #define TMPBUFLEN 21
1071 static ssize_t proc_loginuid_read(struct file * file, char __user * buf,
1072 				  size_t count, loff_t *ppos)
1073 {
1074 	struct inode * inode = file->f_path.dentry->d_inode;
1075 	struct task_struct *task = get_proc_task(inode);
1076 	ssize_t length;
1077 	char tmpbuf[TMPBUFLEN];
1078 
1079 	if (!task)
1080 		return -ESRCH;
1081 	length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
1082 				audit_get_loginuid(task));
1083 	put_task_struct(task);
1084 	return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
1085 }
1086 
1087 static ssize_t proc_loginuid_write(struct file * file, const char __user * buf,
1088 				   size_t count, loff_t *ppos)
1089 {
1090 	struct inode * inode = file->f_path.dentry->d_inode;
1091 	char *page, *tmp;
1092 	ssize_t length;
1093 	uid_t loginuid;
1094 
1095 	if (!capable(CAP_AUDIT_CONTROL))
1096 		return -EPERM;
1097 
1098 	if (current != pid_task(proc_pid(inode), PIDTYPE_PID))
1099 		return -EPERM;
1100 
1101 	if (count >= PAGE_SIZE)
1102 		count = PAGE_SIZE - 1;
1103 
1104 	if (*ppos != 0) {
1105 		/* No partial writes. */
1106 		return -EINVAL;
1107 	}
1108 	page = (char*)__get_free_page(GFP_TEMPORARY);
1109 	if (!page)
1110 		return -ENOMEM;
1111 	length = -EFAULT;
1112 	if (copy_from_user(page, buf, count))
1113 		goto out_free_page;
1114 
1115 	page[count] = '\0';
1116 	loginuid = simple_strtoul(page, &tmp, 10);
1117 	if (tmp == page) {
1118 		length = -EINVAL;
1119 		goto out_free_page;
1120 
1121 	}
1122 	length = audit_set_loginuid(current, loginuid);
1123 	if (likely(length == 0))
1124 		length = count;
1125 
1126 out_free_page:
1127 	free_page((unsigned long) page);
1128 	return length;
1129 }
1130 
1131 static const struct file_operations proc_loginuid_operations = {
1132 	.read		= proc_loginuid_read,
1133 	.write		= proc_loginuid_write,
1134 };
1135 
1136 static ssize_t proc_sessionid_read(struct file * file, char __user * buf,
1137 				  size_t count, loff_t *ppos)
1138 {
1139 	struct inode * inode = file->f_path.dentry->d_inode;
1140 	struct task_struct *task = get_proc_task(inode);
1141 	ssize_t length;
1142 	char tmpbuf[TMPBUFLEN];
1143 
1144 	if (!task)
1145 		return -ESRCH;
1146 	length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
1147 				audit_get_sessionid(task));
1148 	put_task_struct(task);
1149 	return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
1150 }
1151 
1152 static const struct file_operations proc_sessionid_operations = {
1153 	.read		= proc_sessionid_read,
1154 };
1155 #endif
1156 
1157 #ifdef CONFIG_FAULT_INJECTION
1158 static ssize_t proc_fault_inject_read(struct file * file, char __user * buf,
1159 				      size_t count, loff_t *ppos)
1160 {
1161 	struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
1162 	char buffer[PROC_NUMBUF];
1163 	size_t len;
1164 	int make_it_fail;
1165 
1166 	if (!task)
1167 		return -ESRCH;
1168 	make_it_fail = task->make_it_fail;
1169 	put_task_struct(task);
1170 
1171 	len = snprintf(buffer, sizeof(buffer), "%i\n", make_it_fail);
1172 
1173 	return simple_read_from_buffer(buf, count, ppos, buffer, len);
1174 }
1175 
1176 static ssize_t proc_fault_inject_write(struct file * file,
1177 			const char __user * buf, size_t count, loff_t *ppos)
1178 {
1179 	struct task_struct *task;
1180 	char buffer[PROC_NUMBUF], *end;
1181 	int make_it_fail;
1182 
1183 	if (!capable(CAP_SYS_RESOURCE))
1184 		return -EPERM;
1185 	memset(buffer, 0, sizeof(buffer));
1186 	if (count > sizeof(buffer) - 1)
1187 		count = sizeof(buffer) - 1;
1188 	if (copy_from_user(buffer, buf, count))
1189 		return -EFAULT;
1190 	make_it_fail = simple_strtol(strstrip(buffer), &end, 0);
1191 	if (*end)
1192 		return -EINVAL;
1193 	task = get_proc_task(file->f_dentry->d_inode);
1194 	if (!task)
1195 		return -ESRCH;
1196 	task->make_it_fail = make_it_fail;
1197 	put_task_struct(task);
1198 
1199 	return count;
1200 }
1201 
1202 static const struct file_operations proc_fault_inject_operations = {
1203 	.read		= proc_fault_inject_read,
1204 	.write		= proc_fault_inject_write,
1205 };
1206 #endif
1207 
1208 
1209 #ifdef CONFIG_SCHED_DEBUG
1210 /*
1211  * Print out various scheduling related per-task fields:
1212  */
1213 static int sched_show(struct seq_file *m, void *v)
1214 {
1215 	struct inode *inode = m->private;
1216 	struct task_struct *p;
1217 
1218 	p = get_proc_task(inode);
1219 	if (!p)
1220 		return -ESRCH;
1221 	proc_sched_show_task(p, m);
1222 
1223 	put_task_struct(p);
1224 
1225 	return 0;
1226 }
1227 
1228 static ssize_t
1229 sched_write(struct file *file, const char __user *buf,
1230 	    size_t count, loff_t *offset)
1231 {
1232 	struct inode *inode = file->f_path.dentry->d_inode;
1233 	struct task_struct *p;
1234 
1235 	p = get_proc_task(inode);
1236 	if (!p)
1237 		return -ESRCH;
1238 	proc_sched_set_task(p);
1239 
1240 	put_task_struct(p);
1241 
1242 	return count;
1243 }
1244 
1245 static int sched_open(struct inode *inode, struct file *filp)
1246 {
1247 	int ret;
1248 
1249 	ret = single_open(filp, sched_show, NULL);
1250 	if (!ret) {
1251 		struct seq_file *m = filp->private_data;
1252 
1253 		m->private = inode;
1254 	}
1255 	return ret;
1256 }
1257 
1258 static const struct file_operations proc_pid_sched_operations = {
1259 	.open		= sched_open,
1260 	.read		= seq_read,
1261 	.write		= sched_write,
1262 	.llseek		= seq_lseek,
1263 	.release	= single_release,
1264 };
1265 
1266 #endif
1267 
1268 static ssize_t comm_write(struct file *file, const char __user *buf,
1269 				size_t count, loff_t *offset)
1270 {
1271 	struct inode *inode = file->f_path.dentry->d_inode;
1272 	struct task_struct *p;
1273 	char buffer[TASK_COMM_LEN];
1274 
1275 	memset(buffer, 0, sizeof(buffer));
1276 	if (count > sizeof(buffer) - 1)
1277 		count = sizeof(buffer) - 1;
1278 	if (copy_from_user(buffer, buf, count))
1279 		return -EFAULT;
1280 
1281 	p = get_proc_task(inode);
1282 	if (!p)
1283 		return -ESRCH;
1284 
1285 	if (same_thread_group(current, p))
1286 		set_task_comm(p, buffer);
1287 	else
1288 		count = -EINVAL;
1289 
1290 	put_task_struct(p);
1291 
1292 	return count;
1293 }
1294 
1295 static int comm_show(struct seq_file *m, void *v)
1296 {
1297 	struct inode *inode = m->private;
1298 	struct task_struct *p;
1299 
1300 	p = get_proc_task(inode);
1301 	if (!p)
1302 		return -ESRCH;
1303 
1304 	task_lock(p);
1305 	seq_printf(m, "%s\n", p->comm);
1306 	task_unlock(p);
1307 
1308 	put_task_struct(p);
1309 
1310 	return 0;
1311 }
1312 
1313 static int comm_open(struct inode *inode, struct file *filp)
1314 {
1315 	int ret;
1316 
1317 	ret = single_open(filp, comm_show, NULL);
1318 	if (!ret) {
1319 		struct seq_file *m = filp->private_data;
1320 
1321 		m->private = inode;
1322 	}
1323 	return ret;
1324 }
1325 
1326 static const struct file_operations proc_pid_set_comm_operations = {
1327 	.open		= comm_open,
1328 	.read		= seq_read,
1329 	.write		= comm_write,
1330 	.llseek		= seq_lseek,
1331 	.release	= single_release,
1332 };
1333 
1334 /*
1335  * We added or removed a vma mapping the executable. The vmas are only mapped
1336  * during exec and are not mapped with the mmap system call.
1337  * Callers must hold down_write() on the mm's mmap_sem for these
1338  */
1339 void added_exe_file_vma(struct mm_struct *mm)
1340 {
1341 	mm->num_exe_file_vmas++;
1342 }
1343 
1344 void removed_exe_file_vma(struct mm_struct *mm)
1345 {
1346 	mm->num_exe_file_vmas--;
1347 	if ((mm->num_exe_file_vmas == 0) && mm->exe_file){
1348 		fput(mm->exe_file);
1349 		mm->exe_file = NULL;
1350 	}
1351 
1352 }
1353 
1354 void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1355 {
1356 	if (new_exe_file)
1357 		get_file(new_exe_file);
1358 	if (mm->exe_file)
1359 		fput(mm->exe_file);
1360 	mm->exe_file = new_exe_file;
1361 	mm->num_exe_file_vmas = 0;
1362 }
1363 
1364 struct file *get_mm_exe_file(struct mm_struct *mm)
1365 {
1366 	struct file *exe_file;
1367 
1368 	/* We need mmap_sem to protect against races with removal of
1369 	 * VM_EXECUTABLE vmas */
1370 	down_read(&mm->mmap_sem);
1371 	exe_file = mm->exe_file;
1372 	if (exe_file)
1373 		get_file(exe_file);
1374 	up_read(&mm->mmap_sem);
1375 	return exe_file;
1376 }
1377 
1378 void dup_mm_exe_file(struct mm_struct *oldmm, struct mm_struct *newmm)
1379 {
1380 	/* It's safe to write the exe_file pointer without exe_file_lock because
1381 	 * this is called during fork when the task is not yet in /proc */
1382 	newmm->exe_file = get_mm_exe_file(oldmm);
1383 }
1384 
1385 static int proc_exe_link(struct inode *inode, struct path *exe_path)
1386 {
1387 	struct task_struct *task;
1388 	struct mm_struct *mm;
1389 	struct file *exe_file;
1390 
1391 	task = get_proc_task(inode);
1392 	if (!task)
1393 		return -ENOENT;
1394 	mm = get_task_mm(task);
1395 	put_task_struct(task);
1396 	if (!mm)
1397 		return -ENOENT;
1398 	exe_file = get_mm_exe_file(mm);
1399 	mmput(mm);
1400 	if (exe_file) {
1401 		*exe_path = exe_file->f_path;
1402 		path_get(&exe_file->f_path);
1403 		fput(exe_file);
1404 		return 0;
1405 	} else
1406 		return -ENOENT;
1407 }
1408 
1409 static void *proc_pid_follow_link(struct dentry *dentry, struct nameidata *nd)
1410 {
1411 	struct inode *inode = dentry->d_inode;
1412 	int error = -EACCES;
1413 
1414 	/* We don't need a base pointer in the /proc filesystem */
1415 	path_put(&nd->path);
1416 
1417 	/* Are we allowed to snoop on the tasks file descriptors? */
1418 	if (!proc_fd_access_allowed(inode))
1419 		goto out;
1420 
1421 	error = PROC_I(inode)->op.proc_get_link(inode, &nd->path);
1422 out:
1423 	return ERR_PTR(error);
1424 }
1425 
1426 static int do_proc_readlink(struct path *path, char __user *buffer, int buflen)
1427 {
1428 	char *tmp = (char*)__get_free_page(GFP_TEMPORARY);
1429 	char *pathname;
1430 	int len;
1431 
1432 	if (!tmp)
1433 		return -ENOMEM;
1434 
1435 	pathname = d_path(path, tmp, PAGE_SIZE);
1436 	len = PTR_ERR(pathname);
1437 	if (IS_ERR(pathname))
1438 		goto out;
1439 	len = tmp + PAGE_SIZE - 1 - pathname;
1440 
1441 	if (len > buflen)
1442 		len = buflen;
1443 	if (copy_to_user(buffer, pathname, len))
1444 		len = -EFAULT;
1445  out:
1446 	free_page((unsigned long)tmp);
1447 	return len;
1448 }
1449 
1450 static int proc_pid_readlink(struct dentry * dentry, char __user * buffer, int buflen)
1451 {
1452 	int error = -EACCES;
1453 	struct inode *inode = dentry->d_inode;
1454 	struct path path;
1455 
1456 	/* Are we allowed to snoop on the tasks file descriptors? */
1457 	if (!proc_fd_access_allowed(inode))
1458 		goto out;
1459 
1460 	error = PROC_I(inode)->op.proc_get_link(inode, &path);
1461 	if (error)
1462 		goto out;
1463 
1464 	error = do_proc_readlink(&path, buffer, buflen);
1465 	path_put(&path);
1466 out:
1467 	return error;
1468 }
1469 
1470 static const struct inode_operations proc_pid_link_inode_operations = {
1471 	.readlink	= proc_pid_readlink,
1472 	.follow_link	= proc_pid_follow_link,
1473 	.setattr	= proc_setattr,
1474 };
1475 
1476 
1477 /* building an inode */
1478 
1479 static int task_dumpable(struct task_struct *task)
1480 {
1481 	int dumpable = 0;
1482 	struct mm_struct *mm;
1483 
1484 	task_lock(task);
1485 	mm = task->mm;
1486 	if (mm)
1487 		dumpable = get_dumpable(mm);
1488 	task_unlock(task);
1489 	if(dumpable == 1)
1490 		return 1;
1491 	return 0;
1492 }
1493 
1494 
1495 static struct inode *proc_pid_make_inode(struct super_block * sb, struct task_struct *task)
1496 {
1497 	struct inode * inode;
1498 	struct proc_inode *ei;
1499 	const struct cred *cred;
1500 
1501 	/* We need a new inode */
1502 
1503 	inode = new_inode(sb);
1504 	if (!inode)
1505 		goto out;
1506 
1507 	/* Common stuff */
1508 	ei = PROC_I(inode);
1509 	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
1510 	inode->i_op = &proc_def_inode_operations;
1511 
1512 	/*
1513 	 * grab the reference to task.
1514 	 */
1515 	ei->pid = get_task_pid(task, PIDTYPE_PID);
1516 	if (!ei->pid)
1517 		goto out_unlock;
1518 
1519 	if (task_dumpable(task)) {
1520 		rcu_read_lock();
1521 		cred = __task_cred(task);
1522 		inode->i_uid = cred->euid;
1523 		inode->i_gid = cred->egid;
1524 		rcu_read_unlock();
1525 	}
1526 	security_task_to_inode(task, inode);
1527 
1528 out:
1529 	return inode;
1530 
1531 out_unlock:
1532 	iput(inode);
1533 	return NULL;
1534 }
1535 
1536 static int pid_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
1537 {
1538 	struct inode *inode = dentry->d_inode;
1539 	struct task_struct *task;
1540 	const struct cred *cred;
1541 
1542 	generic_fillattr(inode, stat);
1543 
1544 	rcu_read_lock();
1545 	stat->uid = 0;
1546 	stat->gid = 0;
1547 	task = pid_task(proc_pid(inode), PIDTYPE_PID);
1548 	if (task) {
1549 		if ((inode->i_mode == (S_IFDIR|S_IRUGO|S_IXUGO)) ||
1550 		    task_dumpable(task)) {
1551 			cred = __task_cred(task);
1552 			stat->uid = cred->euid;
1553 			stat->gid = cred->egid;
1554 		}
1555 	}
1556 	rcu_read_unlock();
1557 	return 0;
1558 }
1559 
1560 /* dentry stuff */
1561 
1562 /*
1563  *	Exceptional case: normally we are not allowed to unhash a busy
1564  * directory. In this case, however, we can do it - no aliasing problems
1565  * due to the way we treat inodes.
1566  *
1567  * Rewrite the inode's ownerships here because the owning task may have
1568  * performed a setuid(), etc.
1569  *
1570  * Before the /proc/pid/status file was created the only way to read
1571  * the effective uid of a /process was to stat /proc/pid.  Reading
1572  * /proc/pid/status is slow enough that procps and other packages
1573  * kept stating /proc/pid.  To keep the rules in /proc simple I have
1574  * made this apply to all per process world readable and executable
1575  * directories.
1576  */
1577 static int pid_revalidate(struct dentry *dentry, struct nameidata *nd)
1578 {
1579 	struct inode *inode = dentry->d_inode;
1580 	struct task_struct *task = get_proc_task(inode);
1581 	const struct cred *cred;
1582 
1583 	if (task) {
1584 		if ((inode->i_mode == (S_IFDIR|S_IRUGO|S_IXUGO)) ||
1585 		    task_dumpable(task)) {
1586 			rcu_read_lock();
1587 			cred = __task_cred(task);
1588 			inode->i_uid = cred->euid;
1589 			inode->i_gid = cred->egid;
1590 			rcu_read_unlock();
1591 		} else {
1592 			inode->i_uid = 0;
1593 			inode->i_gid = 0;
1594 		}
1595 		inode->i_mode &= ~(S_ISUID | S_ISGID);
1596 		security_task_to_inode(task, inode);
1597 		put_task_struct(task);
1598 		return 1;
1599 	}
1600 	d_drop(dentry);
1601 	return 0;
1602 }
1603 
1604 static int pid_delete_dentry(struct dentry * dentry)
1605 {
1606 	/* Is the task we represent dead?
1607 	 * If so, then don't put the dentry on the lru list,
1608 	 * kill it immediately.
1609 	 */
1610 	return !proc_pid(dentry->d_inode)->tasks[PIDTYPE_PID].first;
1611 }
1612 
1613 static const struct dentry_operations pid_dentry_operations =
1614 {
1615 	.d_revalidate	= pid_revalidate,
1616 	.d_delete	= pid_delete_dentry,
1617 };
1618 
1619 /* Lookups */
1620 
1621 typedef struct dentry *instantiate_t(struct inode *, struct dentry *,
1622 				struct task_struct *, const void *);
1623 
1624 /*
1625  * Fill a directory entry.
1626  *
1627  * If possible create the dcache entry and derive our inode number and
1628  * file type from dcache entry.
1629  *
1630  * Since all of the proc inode numbers are dynamically generated, the inode
1631  * numbers do not exist until the inode is cache.  This means creating the
1632  * the dcache entry in readdir is necessary to keep the inode numbers
1633  * reported by readdir in sync with the inode numbers reported
1634  * by stat.
1635  */
1636 static int proc_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
1637 	char *name, int len,
1638 	instantiate_t instantiate, struct task_struct *task, const void *ptr)
1639 {
1640 	struct dentry *child, *dir = filp->f_path.dentry;
1641 	struct inode *inode;
1642 	struct qstr qname;
1643 	ino_t ino = 0;
1644 	unsigned type = DT_UNKNOWN;
1645 
1646 	qname.name = name;
1647 	qname.len  = len;
1648 	qname.hash = full_name_hash(name, len);
1649 
1650 	child = d_lookup(dir, &qname);
1651 	if (!child) {
1652 		struct dentry *new;
1653 		new = d_alloc(dir, &qname);
1654 		if (new) {
1655 			child = instantiate(dir->d_inode, new, task, ptr);
1656 			if (child)
1657 				dput(new);
1658 			else
1659 				child = new;
1660 		}
1661 	}
1662 	if (!child || IS_ERR(child) || !child->d_inode)
1663 		goto end_instantiate;
1664 	inode = child->d_inode;
1665 	if (inode) {
1666 		ino = inode->i_ino;
1667 		type = inode->i_mode >> 12;
1668 	}
1669 	dput(child);
1670 end_instantiate:
1671 	if (!ino)
1672 		ino = find_inode_number(dir, &qname);
1673 	if (!ino)
1674 		ino = 1;
1675 	return filldir(dirent, name, len, filp->f_pos, ino, type);
1676 }
1677 
1678 static unsigned name_to_int(struct dentry *dentry)
1679 {
1680 	const char *name = dentry->d_name.name;
1681 	int len = dentry->d_name.len;
1682 	unsigned n = 0;
1683 
1684 	if (len > 1 && *name == '0')
1685 		goto out;
1686 	while (len-- > 0) {
1687 		unsigned c = *name++ - '0';
1688 		if (c > 9)
1689 			goto out;
1690 		if (n >= (~0U-9)/10)
1691 			goto out;
1692 		n *= 10;
1693 		n += c;
1694 	}
1695 	return n;
1696 out:
1697 	return ~0U;
1698 }
1699 
1700 #define PROC_FDINFO_MAX 64
1701 
1702 static int proc_fd_info(struct inode *inode, struct path *path, char *info)
1703 {
1704 	struct task_struct *task = get_proc_task(inode);
1705 	struct files_struct *files = NULL;
1706 	struct file *file;
1707 	int fd = proc_fd(inode);
1708 
1709 	if (task) {
1710 		files = get_files_struct(task);
1711 		put_task_struct(task);
1712 	}
1713 	if (files) {
1714 		/*
1715 		 * We are not taking a ref to the file structure, so we must
1716 		 * hold ->file_lock.
1717 		 */
1718 		spin_lock(&files->file_lock);
1719 		file = fcheck_files(files, fd);
1720 		if (file) {
1721 			if (path) {
1722 				*path = file->f_path;
1723 				path_get(&file->f_path);
1724 			}
1725 			if (info)
1726 				snprintf(info, PROC_FDINFO_MAX,
1727 					 "pos:\t%lli\n"
1728 					 "flags:\t0%o\n",
1729 					 (long long) file->f_pos,
1730 					 file->f_flags);
1731 			spin_unlock(&files->file_lock);
1732 			put_files_struct(files);
1733 			return 0;
1734 		}
1735 		spin_unlock(&files->file_lock);
1736 		put_files_struct(files);
1737 	}
1738 	return -ENOENT;
1739 }
1740 
1741 static int proc_fd_link(struct inode *inode, struct path *path)
1742 {
1743 	return proc_fd_info(inode, path, NULL);
1744 }
1745 
1746 static int tid_fd_revalidate(struct dentry *dentry, struct nameidata *nd)
1747 {
1748 	struct inode *inode = dentry->d_inode;
1749 	struct task_struct *task = get_proc_task(inode);
1750 	int fd = proc_fd(inode);
1751 	struct files_struct *files;
1752 	const struct cred *cred;
1753 
1754 	if (task) {
1755 		files = get_files_struct(task);
1756 		if (files) {
1757 			rcu_read_lock();
1758 			if (fcheck_files(files, fd)) {
1759 				rcu_read_unlock();
1760 				put_files_struct(files);
1761 				if (task_dumpable(task)) {
1762 					rcu_read_lock();
1763 					cred = __task_cred(task);
1764 					inode->i_uid = cred->euid;
1765 					inode->i_gid = cred->egid;
1766 					rcu_read_unlock();
1767 				} else {
1768 					inode->i_uid = 0;
1769 					inode->i_gid = 0;
1770 				}
1771 				inode->i_mode &= ~(S_ISUID | S_ISGID);
1772 				security_task_to_inode(task, inode);
1773 				put_task_struct(task);
1774 				return 1;
1775 			}
1776 			rcu_read_unlock();
1777 			put_files_struct(files);
1778 		}
1779 		put_task_struct(task);
1780 	}
1781 	d_drop(dentry);
1782 	return 0;
1783 }
1784 
1785 static const struct dentry_operations tid_fd_dentry_operations =
1786 {
1787 	.d_revalidate	= tid_fd_revalidate,
1788 	.d_delete	= pid_delete_dentry,
1789 };
1790 
1791 static struct dentry *proc_fd_instantiate(struct inode *dir,
1792 	struct dentry *dentry, struct task_struct *task, const void *ptr)
1793 {
1794 	unsigned fd = *(const unsigned *)ptr;
1795 	struct file *file;
1796 	struct files_struct *files;
1797  	struct inode *inode;
1798  	struct proc_inode *ei;
1799 	struct dentry *error = ERR_PTR(-ENOENT);
1800 
1801 	inode = proc_pid_make_inode(dir->i_sb, task);
1802 	if (!inode)
1803 		goto out;
1804 	ei = PROC_I(inode);
1805 	ei->fd = fd;
1806 	files = get_files_struct(task);
1807 	if (!files)
1808 		goto out_iput;
1809 	inode->i_mode = S_IFLNK;
1810 
1811 	/*
1812 	 * We are not taking a ref to the file structure, so we must
1813 	 * hold ->file_lock.
1814 	 */
1815 	spin_lock(&files->file_lock);
1816 	file = fcheck_files(files, fd);
1817 	if (!file)
1818 		goto out_unlock;
1819 	if (file->f_mode & FMODE_READ)
1820 		inode->i_mode |= S_IRUSR | S_IXUSR;
1821 	if (file->f_mode & FMODE_WRITE)
1822 		inode->i_mode |= S_IWUSR | S_IXUSR;
1823 	spin_unlock(&files->file_lock);
1824 	put_files_struct(files);
1825 
1826 	inode->i_op = &proc_pid_link_inode_operations;
1827 	inode->i_size = 64;
1828 	ei->op.proc_get_link = proc_fd_link;
1829 	dentry->d_op = &tid_fd_dentry_operations;
1830 	d_add(dentry, inode);
1831 	/* Close the race of the process dying before we return the dentry */
1832 	if (tid_fd_revalidate(dentry, NULL))
1833 		error = NULL;
1834 
1835  out:
1836 	return error;
1837 out_unlock:
1838 	spin_unlock(&files->file_lock);
1839 	put_files_struct(files);
1840 out_iput:
1841 	iput(inode);
1842 	goto out;
1843 }
1844 
1845 static struct dentry *proc_lookupfd_common(struct inode *dir,
1846 					   struct dentry *dentry,
1847 					   instantiate_t instantiate)
1848 {
1849 	struct task_struct *task = get_proc_task(dir);
1850 	unsigned fd = name_to_int(dentry);
1851 	struct dentry *result = ERR_PTR(-ENOENT);
1852 
1853 	if (!task)
1854 		goto out_no_task;
1855 	if (fd == ~0U)
1856 		goto out;
1857 
1858 	result = instantiate(dir, dentry, task, &fd);
1859 out:
1860 	put_task_struct(task);
1861 out_no_task:
1862 	return result;
1863 }
1864 
1865 static int proc_readfd_common(struct file * filp, void * dirent,
1866 			      filldir_t filldir, instantiate_t instantiate)
1867 {
1868 	struct dentry *dentry = filp->f_path.dentry;
1869 	struct inode *inode = dentry->d_inode;
1870 	struct task_struct *p = get_proc_task(inode);
1871 	unsigned int fd, ino;
1872 	int retval;
1873 	struct files_struct * files;
1874 
1875 	retval = -ENOENT;
1876 	if (!p)
1877 		goto out_no_task;
1878 	retval = 0;
1879 
1880 	fd = filp->f_pos;
1881 	switch (fd) {
1882 		case 0:
1883 			if (filldir(dirent, ".", 1, 0, inode->i_ino, DT_DIR) < 0)
1884 				goto out;
1885 			filp->f_pos++;
1886 		case 1:
1887 			ino = parent_ino(dentry);
1888 			if (filldir(dirent, "..", 2, 1, ino, DT_DIR) < 0)
1889 				goto out;
1890 			filp->f_pos++;
1891 		default:
1892 			files = get_files_struct(p);
1893 			if (!files)
1894 				goto out;
1895 			rcu_read_lock();
1896 			for (fd = filp->f_pos-2;
1897 			     fd < files_fdtable(files)->max_fds;
1898 			     fd++, filp->f_pos++) {
1899 				char name[PROC_NUMBUF];
1900 				int len;
1901 
1902 				if (!fcheck_files(files, fd))
1903 					continue;
1904 				rcu_read_unlock();
1905 
1906 				len = snprintf(name, sizeof(name), "%d", fd);
1907 				if (proc_fill_cache(filp, dirent, filldir,
1908 						    name, len, instantiate,
1909 						    p, &fd) < 0) {
1910 					rcu_read_lock();
1911 					break;
1912 				}
1913 				rcu_read_lock();
1914 			}
1915 			rcu_read_unlock();
1916 			put_files_struct(files);
1917 	}
1918 out:
1919 	put_task_struct(p);
1920 out_no_task:
1921 	return retval;
1922 }
1923 
1924 static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
1925 				    struct nameidata *nd)
1926 {
1927 	return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
1928 }
1929 
1930 static int proc_readfd(struct file *filp, void *dirent, filldir_t filldir)
1931 {
1932 	return proc_readfd_common(filp, dirent, filldir, proc_fd_instantiate);
1933 }
1934 
1935 static ssize_t proc_fdinfo_read(struct file *file, char __user *buf,
1936 				      size_t len, loff_t *ppos)
1937 {
1938 	char tmp[PROC_FDINFO_MAX];
1939 	int err = proc_fd_info(file->f_path.dentry->d_inode, NULL, tmp);
1940 	if (!err)
1941 		err = simple_read_from_buffer(buf, len, ppos, tmp, strlen(tmp));
1942 	return err;
1943 }
1944 
1945 static const struct file_operations proc_fdinfo_file_operations = {
1946 	.open		= nonseekable_open,
1947 	.read		= proc_fdinfo_read,
1948 };
1949 
1950 static const struct file_operations proc_fd_operations = {
1951 	.read		= generic_read_dir,
1952 	.readdir	= proc_readfd,
1953 };
1954 
1955 /*
1956  * /proc/pid/fd needs a special permission handler so that a process can still
1957  * access /proc/self/fd after it has executed a setuid().
1958  */
1959 static int proc_fd_permission(struct inode *inode, int mask)
1960 {
1961 	int rv;
1962 
1963 	rv = generic_permission(inode, mask, NULL);
1964 	if (rv == 0)
1965 		return 0;
1966 	if (task_pid(current) == proc_pid(inode))
1967 		rv = 0;
1968 	return rv;
1969 }
1970 
1971 /*
1972  * proc directories can do almost nothing..
1973  */
1974 static const struct inode_operations proc_fd_inode_operations = {
1975 	.lookup		= proc_lookupfd,
1976 	.permission	= proc_fd_permission,
1977 	.setattr	= proc_setattr,
1978 };
1979 
1980 static struct dentry *proc_fdinfo_instantiate(struct inode *dir,
1981 	struct dentry *dentry, struct task_struct *task, const void *ptr)
1982 {
1983 	unsigned fd = *(unsigned *)ptr;
1984  	struct inode *inode;
1985  	struct proc_inode *ei;
1986 	struct dentry *error = ERR_PTR(-ENOENT);
1987 
1988 	inode = proc_pid_make_inode(dir->i_sb, task);
1989 	if (!inode)
1990 		goto out;
1991 	ei = PROC_I(inode);
1992 	ei->fd = fd;
1993 	inode->i_mode = S_IFREG | S_IRUSR;
1994 	inode->i_fop = &proc_fdinfo_file_operations;
1995 	dentry->d_op = &tid_fd_dentry_operations;
1996 	d_add(dentry, inode);
1997 	/* Close the race of the process dying before we return the dentry */
1998 	if (tid_fd_revalidate(dentry, NULL))
1999 		error = NULL;
2000 
2001  out:
2002 	return error;
2003 }
2004 
2005 static struct dentry *proc_lookupfdinfo(struct inode *dir,
2006 					struct dentry *dentry,
2007 					struct nameidata *nd)
2008 {
2009 	return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
2010 }
2011 
2012 static int proc_readfdinfo(struct file *filp, void *dirent, filldir_t filldir)
2013 {
2014 	return proc_readfd_common(filp, dirent, filldir,
2015 				  proc_fdinfo_instantiate);
2016 }
2017 
2018 static const struct file_operations proc_fdinfo_operations = {
2019 	.read		= generic_read_dir,
2020 	.readdir	= proc_readfdinfo,
2021 };
2022 
2023 /*
2024  * proc directories can do almost nothing..
2025  */
2026 static const struct inode_operations proc_fdinfo_inode_operations = {
2027 	.lookup		= proc_lookupfdinfo,
2028 	.setattr	= proc_setattr,
2029 };
2030 
2031 
2032 static struct dentry *proc_pident_instantiate(struct inode *dir,
2033 	struct dentry *dentry, struct task_struct *task, const void *ptr)
2034 {
2035 	const struct pid_entry *p = ptr;
2036 	struct inode *inode;
2037 	struct proc_inode *ei;
2038 	struct dentry *error = ERR_PTR(-ENOENT);
2039 
2040 	inode = proc_pid_make_inode(dir->i_sb, task);
2041 	if (!inode)
2042 		goto out;
2043 
2044 	ei = PROC_I(inode);
2045 	inode->i_mode = p->mode;
2046 	if (S_ISDIR(inode->i_mode))
2047 		inode->i_nlink = 2;	/* Use getattr to fix if necessary */
2048 	if (p->iop)
2049 		inode->i_op = p->iop;
2050 	if (p->fop)
2051 		inode->i_fop = p->fop;
2052 	ei->op = p->op;
2053 	dentry->d_op = &pid_dentry_operations;
2054 	d_add(dentry, inode);
2055 	/* Close the race of the process dying before we return the dentry */
2056 	if (pid_revalidate(dentry, NULL))
2057 		error = NULL;
2058 out:
2059 	return error;
2060 }
2061 
2062 static struct dentry *proc_pident_lookup(struct inode *dir,
2063 					 struct dentry *dentry,
2064 					 const struct pid_entry *ents,
2065 					 unsigned int nents)
2066 {
2067 	struct dentry *error;
2068 	struct task_struct *task = get_proc_task(dir);
2069 	const struct pid_entry *p, *last;
2070 
2071 	error = ERR_PTR(-ENOENT);
2072 
2073 	if (!task)
2074 		goto out_no_task;
2075 
2076 	/*
2077 	 * Yes, it does not scale. And it should not. Don't add
2078 	 * new entries into /proc/<tgid>/ without very good reasons.
2079 	 */
2080 	last = &ents[nents - 1];
2081 	for (p = ents; p <= last; p++) {
2082 		if (p->len != dentry->d_name.len)
2083 			continue;
2084 		if (!memcmp(dentry->d_name.name, p->name, p->len))
2085 			break;
2086 	}
2087 	if (p > last)
2088 		goto out;
2089 
2090 	error = proc_pident_instantiate(dir, dentry, task, p);
2091 out:
2092 	put_task_struct(task);
2093 out_no_task:
2094 	return error;
2095 }
2096 
2097 static int proc_pident_fill_cache(struct file *filp, void *dirent,
2098 	filldir_t filldir, struct task_struct *task, const struct pid_entry *p)
2099 {
2100 	return proc_fill_cache(filp, dirent, filldir, p->name, p->len,
2101 				proc_pident_instantiate, task, p);
2102 }
2103 
2104 static int proc_pident_readdir(struct file *filp,
2105 		void *dirent, filldir_t filldir,
2106 		const struct pid_entry *ents, unsigned int nents)
2107 {
2108 	int i;
2109 	struct dentry *dentry = filp->f_path.dentry;
2110 	struct inode *inode = dentry->d_inode;
2111 	struct task_struct *task = get_proc_task(inode);
2112 	const struct pid_entry *p, *last;
2113 	ino_t ino;
2114 	int ret;
2115 
2116 	ret = -ENOENT;
2117 	if (!task)
2118 		goto out_no_task;
2119 
2120 	ret = 0;
2121 	i = filp->f_pos;
2122 	switch (i) {
2123 	case 0:
2124 		ino = inode->i_ino;
2125 		if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
2126 			goto out;
2127 		i++;
2128 		filp->f_pos++;
2129 		/* fall through */
2130 	case 1:
2131 		ino = parent_ino(dentry);
2132 		if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
2133 			goto out;
2134 		i++;
2135 		filp->f_pos++;
2136 		/* fall through */
2137 	default:
2138 		i -= 2;
2139 		if (i >= nents) {
2140 			ret = 1;
2141 			goto out;
2142 		}
2143 		p = ents + i;
2144 		last = &ents[nents - 1];
2145 		while (p <= last) {
2146 			if (proc_pident_fill_cache(filp, dirent, filldir, task, p) < 0)
2147 				goto out;
2148 			filp->f_pos++;
2149 			p++;
2150 		}
2151 	}
2152 
2153 	ret = 1;
2154 out:
2155 	put_task_struct(task);
2156 out_no_task:
2157 	return ret;
2158 }
2159 
2160 #ifdef CONFIG_SECURITY
2161 static ssize_t proc_pid_attr_read(struct file * file, char __user * buf,
2162 				  size_t count, loff_t *ppos)
2163 {
2164 	struct inode * inode = file->f_path.dentry->d_inode;
2165 	char *p = NULL;
2166 	ssize_t length;
2167 	struct task_struct *task = get_proc_task(inode);
2168 
2169 	if (!task)
2170 		return -ESRCH;
2171 
2172 	length = security_getprocattr(task,
2173 				      (char*)file->f_path.dentry->d_name.name,
2174 				      &p);
2175 	put_task_struct(task);
2176 	if (length > 0)
2177 		length = simple_read_from_buffer(buf, count, ppos, p, length);
2178 	kfree(p);
2179 	return length;
2180 }
2181 
2182 static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
2183 				   size_t count, loff_t *ppos)
2184 {
2185 	struct inode * inode = file->f_path.dentry->d_inode;
2186 	char *page;
2187 	ssize_t length;
2188 	struct task_struct *task = get_proc_task(inode);
2189 
2190 	length = -ESRCH;
2191 	if (!task)
2192 		goto out_no_task;
2193 	if (count > PAGE_SIZE)
2194 		count = PAGE_SIZE;
2195 
2196 	/* No partial writes. */
2197 	length = -EINVAL;
2198 	if (*ppos != 0)
2199 		goto out;
2200 
2201 	length = -ENOMEM;
2202 	page = (char*)__get_free_page(GFP_TEMPORARY);
2203 	if (!page)
2204 		goto out;
2205 
2206 	length = -EFAULT;
2207 	if (copy_from_user(page, buf, count))
2208 		goto out_free;
2209 
2210 	/* Guard against adverse ptrace interaction */
2211 	length = mutex_lock_interruptible(&task->cred_guard_mutex);
2212 	if (length < 0)
2213 		goto out_free;
2214 
2215 	length = security_setprocattr(task,
2216 				      (char*)file->f_path.dentry->d_name.name,
2217 				      (void*)page, count);
2218 	mutex_unlock(&task->cred_guard_mutex);
2219 out_free:
2220 	free_page((unsigned long) page);
2221 out:
2222 	put_task_struct(task);
2223 out_no_task:
2224 	return length;
2225 }
2226 
2227 static const struct file_operations proc_pid_attr_operations = {
2228 	.read		= proc_pid_attr_read,
2229 	.write		= proc_pid_attr_write,
2230 };
2231 
2232 static const struct pid_entry attr_dir_stuff[] = {
2233 	REG("current",    S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2234 	REG("prev",       S_IRUGO,	   proc_pid_attr_operations),
2235 	REG("exec",       S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2236 	REG("fscreate",   S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2237 	REG("keycreate",  S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2238 	REG("sockcreate", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2239 };
2240 
2241 static int proc_attr_dir_readdir(struct file * filp,
2242 			     void * dirent, filldir_t filldir)
2243 {
2244 	return proc_pident_readdir(filp,dirent,filldir,
2245 				   attr_dir_stuff,ARRAY_SIZE(attr_dir_stuff));
2246 }
2247 
2248 static const struct file_operations proc_attr_dir_operations = {
2249 	.read		= generic_read_dir,
2250 	.readdir	= proc_attr_dir_readdir,
2251 };
2252 
2253 static struct dentry *proc_attr_dir_lookup(struct inode *dir,
2254 				struct dentry *dentry, struct nameidata *nd)
2255 {
2256 	return proc_pident_lookup(dir, dentry,
2257 				  attr_dir_stuff, ARRAY_SIZE(attr_dir_stuff));
2258 }
2259 
2260 static const struct inode_operations proc_attr_dir_inode_operations = {
2261 	.lookup		= proc_attr_dir_lookup,
2262 	.getattr	= pid_getattr,
2263 	.setattr	= proc_setattr,
2264 };
2265 
2266 #endif
2267 
2268 #ifdef CONFIG_ELF_CORE
2269 static ssize_t proc_coredump_filter_read(struct file *file, char __user *buf,
2270 					 size_t count, loff_t *ppos)
2271 {
2272 	struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
2273 	struct mm_struct *mm;
2274 	char buffer[PROC_NUMBUF];
2275 	size_t len;
2276 	int ret;
2277 
2278 	if (!task)
2279 		return -ESRCH;
2280 
2281 	ret = 0;
2282 	mm = get_task_mm(task);
2283 	if (mm) {
2284 		len = snprintf(buffer, sizeof(buffer), "%08lx\n",
2285 			       ((mm->flags & MMF_DUMP_FILTER_MASK) >>
2286 				MMF_DUMP_FILTER_SHIFT));
2287 		mmput(mm);
2288 		ret = simple_read_from_buffer(buf, count, ppos, buffer, len);
2289 	}
2290 
2291 	put_task_struct(task);
2292 
2293 	return ret;
2294 }
2295 
2296 static ssize_t proc_coredump_filter_write(struct file *file,
2297 					  const char __user *buf,
2298 					  size_t count,
2299 					  loff_t *ppos)
2300 {
2301 	struct task_struct *task;
2302 	struct mm_struct *mm;
2303 	char buffer[PROC_NUMBUF], *end;
2304 	unsigned int val;
2305 	int ret;
2306 	int i;
2307 	unsigned long mask;
2308 
2309 	ret = -EFAULT;
2310 	memset(buffer, 0, sizeof(buffer));
2311 	if (count > sizeof(buffer) - 1)
2312 		count = sizeof(buffer) - 1;
2313 	if (copy_from_user(buffer, buf, count))
2314 		goto out_no_task;
2315 
2316 	ret = -EINVAL;
2317 	val = (unsigned int)simple_strtoul(buffer, &end, 0);
2318 	if (*end == '\n')
2319 		end++;
2320 	if (end - buffer == 0)
2321 		goto out_no_task;
2322 
2323 	ret = -ESRCH;
2324 	task = get_proc_task(file->f_dentry->d_inode);
2325 	if (!task)
2326 		goto out_no_task;
2327 
2328 	ret = end - buffer;
2329 	mm = get_task_mm(task);
2330 	if (!mm)
2331 		goto out_no_mm;
2332 
2333 	for (i = 0, mask = 1; i < MMF_DUMP_FILTER_BITS; i++, mask <<= 1) {
2334 		if (val & mask)
2335 			set_bit(i + MMF_DUMP_FILTER_SHIFT, &mm->flags);
2336 		else
2337 			clear_bit(i + MMF_DUMP_FILTER_SHIFT, &mm->flags);
2338 	}
2339 
2340 	mmput(mm);
2341  out_no_mm:
2342 	put_task_struct(task);
2343  out_no_task:
2344 	return ret;
2345 }
2346 
2347 static const struct file_operations proc_coredump_filter_operations = {
2348 	.read		= proc_coredump_filter_read,
2349 	.write		= proc_coredump_filter_write,
2350 };
2351 #endif
2352 
2353 /*
2354  * /proc/self:
2355  */
2356 static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
2357 			      int buflen)
2358 {
2359 	struct pid_namespace *ns = dentry->d_sb->s_fs_info;
2360 	pid_t tgid = task_tgid_nr_ns(current, ns);
2361 	char tmp[PROC_NUMBUF];
2362 	if (!tgid)
2363 		return -ENOENT;
2364 	sprintf(tmp, "%d", tgid);
2365 	return vfs_readlink(dentry,buffer,buflen,tmp);
2366 }
2367 
2368 static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)
2369 {
2370 	struct pid_namespace *ns = dentry->d_sb->s_fs_info;
2371 	pid_t tgid = task_tgid_nr_ns(current, ns);
2372 	char *name = ERR_PTR(-ENOENT);
2373 	if (tgid) {
2374 		name = __getname();
2375 		if (!name)
2376 			name = ERR_PTR(-ENOMEM);
2377 		else
2378 			sprintf(name, "%d", tgid);
2379 	}
2380 	nd_set_link(nd, name);
2381 	return NULL;
2382 }
2383 
2384 static void proc_self_put_link(struct dentry *dentry, struct nameidata *nd,
2385 				void *cookie)
2386 {
2387 	char *s = nd_get_link(nd);
2388 	if (!IS_ERR(s))
2389 		__putname(s);
2390 }
2391 
2392 static const struct inode_operations proc_self_inode_operations = {
2393 	.readlink	= proc_self_readlink,
2394 	.follow_link	= proc_self_follow_link,
2395 	.put_link	= proc_self_put_link,
2396 };
2397 
2398 /*
2399  * proc base
2400  *
2401  * These are the directory entries in the root directory of /proc
2402  * that properly belong to the /proc filesystem, as they describe
2403  * describe something that is process related.
2404  */
2405 static const struct pid_entry proc_base_stuff[] = {
2406 	NOD("self", S_IFLNK|S_IRWXUGO,
2407 		&proc_self_inode_operations, NULL, {}),
2408 };
2409 
2410 /*
2411  *	Exceptional case: normally we are not allowed to unhash a busy
2412  * directory. In this case, however, we can do it - no aliasing problems
2413  * due to the way we treat inodes.
2414  */
2415 static int proc_base_revalidate(struct dentry *dentry, struct nameidata *nd)
2416 {
2417 	struct inode *inode = dentry->d_inode;
2418 	struct task_struct *task = get_proc_task(inode);
2419 	if (task) {
2420 		put_task_struct(task);
2421 		return 1;
2422 	}
2423 	d_drop(dentry);
2424 	return 0;
2425 }
2426 
2427 static const struct dentry_operations proc_base_dentry_operations =
2428 {
2429 	.d_revalidate	= proc_base_revalidate,
2430 	.d_delete	= pid_delete_dentry,
2431 };
2432 
2433 static struct dentry *proc_base_instantiate(struct inode *dir,
2434 	struct dentry *dentry, struct task_struct *task, const void *ptr)
2435 {
2436 	const struct pid_entry *p = ptr;
2437 	struct inode *inode;
2438 	struct proc_inode *ei;
2439 	struct dentry *error = ERR_PTR(-EINVAL);
2440 
2441 	/* Allocate the inode */
2442 	error = ERR_PTR(-ENOMEM);
2443 	inode = new_inode(dir->i_sb);
2444 	if (!inode)
2445 		goto out;
2446 
2447 	/* Initialize the inode */
2448 	ei = PROC_I(inode);
2449 	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
2450 
2451 	/*
2452 	 * grab the reference to the task.
2453 	 */
2454 	ei->pid = get_task_pid(task, PIDTYPE_PID);
2455 	if (!ei->pid)
2456 		goto out_iput;
2457 
2458 	inode->i_mode = p->mode;
2459 	if (S_ISDIR(inode->i_mode))
2460 		inode->i_nlink = 2;
2461 	if (S_ISLNK(inode->i_mode))
2462 		inode->i_size = 64;
2463 	if (p->iop)
2464 		inode->i_op = p->iop;
2465 	if (p->fop)
2466 		inode->i_fop = p->fop;
2467 	ei->op = p->op;
2468 	dentry->d_op = &proc_base_dentry_operations;
2469 	d_add(dentry, inode);
2470 	error = NULL;
2471 out:
2472 	return error;
2473 out_iput:
2474 	iput(inode);
2475 	goto out;
2476 }
2477 
2478 static struct dentry *proc_base_lookup(struct inode *dir, struct dentry *dentry)
2479 {
2480 	struct dentry *error;
2481 	struct task_struct *task = get_proc_task(dir);
2482 	const struct pid_entry *p, *last;
2483 
2484 	error = ERR_PTR(-ENOENT);
2485 
2486 	if (!task)
2487 		goto out_no_task;
2488 
2489 	/* Lookup the directory entry */
2490 	last = &proc_base_stuff[ARRAY_SIZE(proc_base_stuff) - 1];
2491 	for (p = proc_base_stuff; p <= last; p++) {
2492 		if (p->len != dentry->d_name.len)
2493 			continue;
2494 		if (!memcmp(dentry->d_name.name, p->name, p->len))
2495 			break;
2496 	}
2497 	if (p > last)
2498 		goto out;
2499 
2500 	error = proc_base_instantiate(dir, dentry, task, p);
2501 
2502 out:
2503 	put_task_struct(task);
2504 out_no_task:
2505 	return error;
2506 }
2507 
2508 static int proc_base_fill_cache(struct file *filp, void *dirent,
2509 	filldir_t filldir, struct task_struct *task, const struct pid_entry *p)
2510 {
2511 	return proc_fill_cache(filp, dirent, filldir, p->name, p->len,
2512 				proc_base_instantiate, task, p);
2513 }
2514 
2515 #ifdef CONFIG_TASK_IO_ACCOUNTING
2516 static int do_io_accounting(struct task_struct *task, char *buffer, int whole)
2517 {
2518 	struct task_io_accounting acct = task->ioac;
2519 	unsigned long flags;
2520 
2521 	if (whole && lock_task_sighand(task, &flags)) {
2522 		struct task_struct *t = task;
2523 
2524 		task_io_accounting_add(&acct, &task->signal->ioac);
2525 		while_each_thread(task, t)
2526 			task_io_accounting_add(&acct, &t->ioac);
2527 
2528 		unlock_task_sighand(task, &flags);
2529 	}
2530 	return sprintf(buffer,
2531 			"rchar: %llu\n"
2532 			"wchar: %llu\n"
2533 			"syscr: %llu\n"
2534 			"syscw: %llu\n"
2535 			"read_bytes: %llu\n"
2536 			"write_bytes: %llu\n"
2537 			"cancelled_write_bytes: %llu\n",
2538 			(unsigned long long)acct.rchar,
2539 			(unsigned long long)acct.wchar,
2540 			(unsigned long long)acct.syscr,
2541 			(unsigned long long)acct.syscw,
2542 			(unsigned long long)acct.read_bytes,
2543 			(unsigned long long)acct.write_bytes,
2544 			(unsigned long long)acct.cancelled_write_bytes);
2545 }
2546 
2547 static int proc_tid_io_accounting(struct task_struct *task, char *buffer)
2548 {
2549 	return do_io_accounting(task, buffer, 0);
2550 }
2551 
2552 static int proc_tgid_io_accounting(struct task_struct *task, char *buffer)
2553 {
2554 	return do_io_accounting(task, buffer, 1);
2555 }
2556 #endif /* CONFIG_TASK_IO_ACCOUNTING */
2557 
2558 static int proc_pid_personality(struct seq_file *m, struct pid_namespace *ns,
2559 				struct pid *pid, struct task_struct *task)
2560 {
2561 	seq_printf(m, "%08x\n", task->personality);
2562 	return 0;
2563 }
2564 
2565 /*
2566  * Thread groups
2567  */
2568 static const struct file_operations proc_task_operations;
2569 static const struct inode_operations proc_task_inode_operations;
2570 
2571 static const struct pid_entry tgid_base_stuff[] = {
2572 	DIR("task",       S_IRUGO|S_IXUGO, proc_task_inode_operations, proc_task_operations),
2573 	DIR("fd",         S_IRUSR|S_IXUSR, proc_fd_inode_operations, proc_fd_operations),
2574 	DIR("fdinfo",     S_IRUSR|S_IXUSR, proc_fdinfo_inode_operations, proc_fdinfo_operations),
2575 #ifdef CONFIG_NET
2576 	DIR("net",        S_IRUGO|S_IXUGO, proc_net_inode_operations, proc_net_operations),
2577 #endif
2578 	REG("environ",    S_IRUSR, proc_environ_operations),
2579 	INF("auxv",       S_IRUSR, proc_pid_auxv),
2580 	ONE("status",     S_IRUGO, proc_pid_status),
2581 	ONE("personality", S_IRUSR, proc_pid_personality),
2582 	INF("limits",	  S_IRUSR, proc_pid_limits),
2583 #ifdef CONFIG_SCHED_DEBUG
2584 	REG("sched",      S_IRUGO|S_IWUSR, proc_pid_sched_operations),
2585 #endif
2586 	REG("comm",      S_IRUGO|S_IWUSR, proc_pid_set_comm_operations),
2587 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
2588 	INF("syscall",    S_IRUSR, proc_pid_syscall),
2589 #endif
2590 	INF("cmdline",    S_IRUGO, proc_pid_cmdline),
2591 	ONE("stat",       S_IRUGO, proc_tgid_stat),
2592 	ONE("statm",      S_IRUGO, proc_pid_statm),
2593 	REG("maps",       S_IRUGO, proc_maps_operations),
2594 #ifdef CONFIG_NUMA
2595 	REG("numa_maps",  S_IRUGO, proc_numa_maps_operations),
2596 #endif
2597 	REG("mem",        S_IRUSR|S_IWUSR, proc_mem_operations),
2598 	LNK("cwd",        proc_cwd_link),
2599 	LNK("root",       proc_root_link),
2600 	LNK("exe",        proc_exe_link),
2601 	REG("mounts",     S_IRUGO, proc_mounts_operations),
2602 	REG("mountinfo",  S_IRUGO, proc_mountinfo_operations),
2603 	REG("mountstats", S_IRUSR, proc_mountstats_operations),
2604 #ifdef CONFIG_PROC_PAGE_MONITOR
2605 	REG("clear_refs", S_IWUSR, proc_clear_refs_operations),
2606 	REG("smaps",      S_IRUGO, proc_smaps_operations),
2607 	REG("pagemap",    S_IRUSR, proc_pagemap_operations),
2608 #endif
2609 #ifdef CONFIG_SECURITY
2610 	DIR("attr",       S_IRUGO|S_IXUGO, proc_attr_dir_inode_operations, proc_attr_dir_operations),
2611 #endif
2612 #ifdef CONFIG_KALLSYMS
2613 	INF("wchan",      S_IRUGO, proc_pid_wchan),
2614 #endif
2615 #ifdef CONFIG_STACKTRACE
2616 	ONE("stack",      S_IRUSR, proc_pid_stack),
2617 #endif
2618 #ifdef CONFIG_SCHEDSTATS
2619 	INF("schedstat",  S_IRUGO, proc_pid_schedstat),
2620 #endif
2621 #ifdef CONFIG_LATENCYTOP
2622 	REG("latency",  S_IRUGO, proc_lstats_operations),
2623 #endif
2624 #ifdef CONFIG_PROC_PID_CPUSET
2625 	REG("cpuset",     S_IRUGO, proc_cpuset_operations),
2626 #endif
2627 #ifdef CONFIG_CGROUPS
2628 	REG("cgroup",  S_IRUGO, proc_cgroup_operations),
2629 #endif
2630 	INF("oom_score",  S_IRUGO, proc_oom_score),
2631 	REG("oom_adj",    S_IRUGO|S_IWUSR, proc_oom_adjust_operations),
2632 #ifdef CONFIG_AUDITSYSCALL
2633 	REG("loginuid",   S_IWUSR|S_IRUGO, proc_loginuid_operations),
2634 	REG("sessionid",  S_IRUGO, proc_sessionid_operations),
2635 #endif
2636 #ifdef CONFIG_FAULT_INJECTION
2637 	REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
2638 #endif
2639 #ifdef CONFIG_ELF_CORE
2640 	REG("coredump_filter", S_IRUGO|S_IWUSR, proc_coredump_filter_operations),
2641 #endif
2642 #ifdef CONFIG_TASK_IO_ACCOUNTING
2643 	INF("io",	S_IRUGO, proc_tgid_io_accounting),
2644 #endif
2645 };
2646 
2647 static int proc_tgid_base_readdir(struct file * filp,
2648 			     void * dirent, filldir_t filldir)
2649 {
2650 	return proc_pident_readdir(filp,dirent,filldir,
2651 				   tgid_base_stuff,ARRAY_SIZE(tgid_base_stuff));
2652 }
2653 
2654 static const struct file_operations proc_tgid_base_operations = {
2655 	.read		= generic_read_dir,
2656 	.readdir	= proc_tgid_base_readdir,
2657 };
2658 
2659 static struct dentry *proc_tgid_base_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd){
2660 	return proc_pident_lookup(dir, dentry,
2661 				  tgid_base_stuff, ARRAY_SIZE(tgid_base_stuff));
2662 }
2663 
2664 static const struct inode_operations proc_tgid_base_inode_operations = {
2665 	.lookup		= proc_tgid_base_lookup,
2666 	.getattr	= pid_getattr,
2667 	.setattr	= proc_setattr,
2668 };
2669 
2670 static void proc_flush_task_mnt(struct vfsmount *mnt, pid_t pid, pid_t tgid)
2671 {
2672 	struct dentry *dentry, *leader, *dir;
2673 	char buf[PROC_NUMBUF];
2674 	struct qstr name;
2675 
2676 	name.name = buf;
2677 	name.len = snprintf(buf, sizeof(buf), "%d", pid);
2678 	dentry = d_hash_and_lookup(mnt->mnt_root, &name);
2679 	if (dentry) {
2680 		shrink_dcache_parent(dentry);
2681 		d_drop(dentry);
2682 		dput(dentry);
2683 	}
2684 
2685 	name.name = buf;
2686 	name.len = snprintf(buf, sizeof(buf), "%d", tgid);
2687 	leader = d_hash_and_lookup(mnt->mnt_root, &name);
2688 	if (!leader)
2689 		goto out;
2690 
2691 	name.name = "task";
2692 	name.len = strlen(name.name);
2693 	dir = d_hash_and_lookup(leader, &name);
2694 	if (!dir)
2695 		goto out_put_leader;
2696 
2697 	name.name = buf;
2698 	name.len = snprintf(buf, sizeof(buf), "%d", pid);
2699 	dentry = d_hash_and_lookup(dir, &name);
2700 	if (dentry) {
2701 		shrink_dcache_parent(dentry);
2702 		d_drop(dentry);
2703 		dput(dentry);
2704 	}
2705 
2706 	dput(dir);
2707 out_put_leader:
2708 	dput(leader);
2709 out:
2710 	return;
2711 }
2712 
2713 /**
2714  * proc_flush_task -  Remove dcache entries for @task from the /proc dcache.
2715  * @task: task that should be flushed.
2716  *
2717  * When flushing dentries from proc, one needs to flush them from global
2718  * proc (proc_mnt) and from all the namespaces' procs this task was seen
2719  * in. This call is supposed to do all of this job.
2720  *
2721  * Looks in the dcache for
2722  * /proc/@pid
2723  * /proc/@tgid/task/@pid
2724  * if either directory is present flushes it and all of it'ts children
2725  * from the dcache.
2726  *
2727  * It is safe and reasonable to cache /proc entries for a task until
2728  * that task exits.  After that they just clog up the dcache with
2729  * useless entries, possibly causing useful dcache entries to be
2730  * flushed instead.  This routine is proved to flush those useless
2731  * dcache entries at process exit time.
2732  *
2733  * NOTE: This routine is just an optimization so it does not guarantee
2734  *       that no dcache entries will exist at process exit time it
2735  *       just makes it very unlikely that any will persist.
2736  */
2737 
2738 void proc_flush_task(struct task_struct *task)
2739 {
2740 	int i;
2741 	struct pid *pid, *tgid;
2742 	struct upid *upid;
2743 
2744 	pid = task_pid(task);
2745 	tgid = task_tgid(task);
2746 
2747 	for (i = 0; i <= pid->level; i++) {
2748 		upid = &pid->numbers[i];
2749 		proc_flush_task_mnt(upid->ns->proc_mnt, upid->nr,
2750 					tgid->numbers[i].nr);
2751 	}
2752 
2753 	upid = &pid->numbers[pid->level];
2754 	if (upid->nr == 1)
2755 		pid_ns_release_proc(upid->ns);
2756 }
2757 
2758 static struct dentry *proc_pid_instantiate(struct inode *dir,
2759 					   struct dentry * dentry,
2760 					   struct task_struct *task, const void *ptr)
2761 {
2762 	struct dentry *error = ERR_PTR(-ENOENT);
2763 	struct inode *inode;
2764 
2765 	inode = proc_pid_make_inode(dir->i_sb, task);
2766 	if (!inode)
2767 		goto out;
2768 
2769 	inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
2770 	inode->i_op = &proc_tgid_base_inode_operations;
2771 	inode->i_fop = &proc_tgid_base_operations;
2772 	inode->i_flags|=S_IMMUTABLE;
2773 
2774 	inode->i_nlink = 2 + pid_entry_count_dirs(tgid_base_stuff,
2775 		ARRAY_SIZE(tgid_base_stuff));
2776 
2777 	dentry->d_op = &pid_dentry_operations;
2778 
2779 	d_add(dentry, inode);
2780 	/* Close the race of the process dying before we return the dentry */
2781 	if (pid_revalidate(dentry, NULL))
2782 		error = NULL;
2783 out:
2784 	return error;
2785 }
2786 
2787 struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd)
2788 {
2789 	struct dentry *result = ERR_PTR(-ENOENT);
2790 	struct task_struct *task;
2791 	unsigned tgid;
2792 	struct pid_namespace *ns;
2793 
2794 	result = proc_base_lookup(dir, dentry);
2795 	if (!IS_ERR(result) || PTR_ERR(result) != -ENOENT)
2796 		goto out;
2797 
2798 	tgid = name_to_int(dentry);
2799 	if (tgid == ~0U)
2800 		goto out;
2801 
2802 	ns = dentry->d_sb->s_fs_info;
2803 	rcu_read_lock();
2804 	task = find_task_by_pid_ns(tgid, ns);
2805 	if (task)
2806 		get_task_struct(task);
2807 	rcu_read_unlock();
2808 	if (!task)
2809 		goto out;
2810 
2811 	result = proc_pid_instantiate(dir, dentry, task, NULL);
2812 	put_task_struct(task);
2813 out:
2814 	return result;
2815 }
2816 
2817 /*
2818  * Find the first task with tgid >= tgid
2819  *
2820  */
2821 struct tgid_iter {
2822 	unsigned int tgid;
2823 	struct task_struct *task;
2824 };
2825 static struct tgid_iter next_tgid(struct pid_namespace *ns, struct tgid_iter iter)
2826 {
2827 	struct pid *pid;
2828 
2829 	if (iter.task)
2830 		put_task_struct(iter.task);
2831 	rcu_read_lock();
2832 retry:
2833 	iter.task = NULL;
2834 	pid = find_ge_pid(iter.tgid, ns);
2835 	if (pid) {
2836 		iter.tgid = pid_nr_ns(pid, ns);
2837 		iter.task = pid_task(pid, PIDTYPE_PID);
2838 		/* What we to know is if the pid we have find is the
2839 		 * pid of a thread_group_leader.  Testing for task
2840 		 * being a thread_group_leader is the obvious thing
2841 		 * todo but there is a window when it fails, due to
2842 		 * the pid transfer logic in de_thread.
2843 		 *
2844 		 * So we perform the straight forward test of seeing
2845 		 * if the pid we have found is the pid of a thread
2846 		 * group leader, and don't worry if the task we have
2847 		 * found doesn't happen to be a thread group leader.
2848 		 * As we don't care in the case of readdir.
2849 		 */
2850 		if (!iter.task || !has_group_leader_pid(iter.task)) {
2851 			iter.tgid += 1;
2852 			goto retry;
2853 		}
2854 		get_task_struct(iter.task);
2855 	}
2856 	rcu_read_unlock();
2857 	return iter;
2858 }
2859 
2860 #define TGID_OFFSET (FIRST_PROCESS_ENTRY + ARRAY_SIZE(proc_base_stuff))
2861 
2862 static int proc_pid_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
2863 	struct tgid_iter iter)
2864 {
2865 	char name[PROC_NUMBUF];
2866 	int len = snprintf(name, sizeof(name), "%d", iter.tgid);
2867 	return proc_fill_cache(filp, dirent, filldir, name, len,
2868 				proc_pid_instantiate, iter.task, NULL);
2869 }
2870 
2871 /* for the /proc/ directory itself, after non-process stuff has been done */
2872 int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
2873 {
2874 	unsigned int nr = filp->f_pos - FIRST_PROCESS_ENTRY;
2875 	struct task_struct *reaper = get_proc_task(filp->f_path.dentry->d_inode);
2876 	struct tgid_iter iter;
2877 	struct pid_namespace *ns;
2878 
2879 	if (!reaper)
2880 		goto out_no_task;
2881 
2882 	for (; nr < ARRAY_SIZE(proc_base_stuff); filp->f_pos++, nr++) {
2883 		const struct pid_entry *p = &proc_base_stuff[nr];
2884 		if (proc_base_fill_cache(filp, dirent, filldir, reaper, p) < 0)
2885 			goto out;
2886 	}
2887 
2888 	ns = filp->f_dentry->d_sb->s_fs_info;
2889 	iter.task = NULL;
2890 	iter.tgid = filp->f_pos - TGID_OFFSET;
2891 	for (iter = next_tgid(ns, iter);
2892 	     iter.task;
2893 	     iter.tgid += 1, iter = next_tgid(ns, iter)) {
2894 		filp->f_pos = iter.tgid + TGID_OFFSET;
2895 		if (proc_pid_fill_cache(filp, dirent, filldir, iter) < 0) {
2896 			put_task_struct(iter.task);
2897 			goto out;
2898 		}
2899 	}
2900 	filp->f_pos = PID_MAX_LIMIT + TGID_OFFSET;
2901 out:
2902 	put_task_struct(reaper);
2903 out_no_task:
2904 	return 0;
2905 }
2906 
2907 /*
2908  * Tasks
2909  */
2910 static const struct pid_entry tid_base_stuff[] = {
2911 	DIR("fd",        S_IRUSR|S_IXUSR, proc_fd_inode_operations, proc_fd_operations),
2912 	DIR("fdinfo",    S_IRUSR|S_IXUSR, proc_fdinfo_inode_operations, proc_fd_operations),
2913 	REG("environ",   S_IRUSR, proc_environ_operations),
2914 	INF("auxv",      S_IRUSR, proc_pid_auxv),
2915 	ONE("status",    S_IRUGO, proc_pid_status),
2916 	ONE("personality", S_IRUSR, proc_pid_personality),
2917 	INF("limits",	 S_IRUSR, proc_pid_limits),
2918 #ifdef CONFIG_SCHED_DEBUG
2919 	REG("sched",     S_IRUGO|S_IWUSR, proc_pid_sched_operations),
2920 #endif
2921 	REG("comm",      S_IRUGO|S_IWUSR, proc_pid_set_comm_operations),
2922 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
2923 	INF("syscall",   S_IRUSR, proc_pid_syscall),
2924 #endif
2925 	INF("cmdline",   S_IRUGO, proc_pid_cmdline),
2926 	ONE("stat",      S_IRUGO, proc_tid_stat),
2927 	ONE("statm",     S_IRUGO, proc_pid_statm),
2928 	REG("maps",      S_IRUGO, proc_maps_operations),
2929 #ifdef CONFIG_NUMA
2930 	REG("numa_maps", S_IRUGO, proc_numa_maps_operations),
2931 #endif
2932 	REG("mem",       S_IRUSR|S_IWUSR, proc_mem_operations),
2933 	LNK("cwd",       proc_cwd_link),
2934 	LNK("root",      proc_root_link),
2935 	LNK("exe",       proc_exe_link),
2936 	REG("mounts",    S_IRUGO, proc_mounts_operations),
2937 	REG("mountinfo",  S_IRUGO, proc_mountinfo_operations),
2938 #ifdef CONFIG_PROC_PAGE_MONITOR
2939 	REG("clear_refs", S_IWUSR, proc_clear_refs_operations),
2940 	REG("smaps",     S_IRUGO, proc_smaps_operations),
2941 	REG("pagemap",    S_IRUSR, proc_pagemap_operations),
2942 #endif
2943 #ifdef CONFIG_SECURITY
2944 	DIR("attr",      S_IRUGO|S_IXUGO, proc_attr_dir_inode_operations, proc_attr_dir_operations),
2945 #endif
2946 #ifdef CONFIG_KALLSYMS
2947 	INF("wchan",     S_IRUGO, proc_pid_wchan),
2948 #endif
2949 #ifdef CONFIG_STACKTRACE
2950 	ONE("stack",      S_IRUSR, proc_pid_stack),
2951 #endif
2952 #ifdef CONFIG_SCHEDSTATS
2953 	INF("schedstat", S_IRUGO, proc_pid_schedstat),
2954 #endif
2955 #ifdef CONFIG_LATENCYTOP
2956 	REG("latency",  S_IRUGO, proc_lstats_operations),
2957 #endif
2958 #ifdef CONFIG_PROC_PID_CPUSET
2959 	REG("cpuset",    S_IRUGO, proc_cpuset_operations),
2960 #endif
2961 #ifdef CONFIG_CGROUPS
2962 	REG("cgroup",  S_IRUGO, proc_cgroup_operations),
2963 #endif
2964 	INF("oom_score", S_IRUGO, proc_oom_score),
2965 	REG("oom_adj",   S_IRUGO|S_IWUSR, proc_oom_adjust_operations),
2966 #ifdef CONFIG_AUDITSYSCALL
2967 	REG("loginuid",  S_IWUSR|S_IRUGO, proc_loginuid_operations),
2968 	REG("sessionid",  S_IRUSR, proc_sessionid_operations),
2969 #endif
2970 #ifdef CONFIG_FAULT_INJECTION
2971 	REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
2972 #endif
2973 #ifdef CONFIG_TASK_IO_ACCOUNTING
2974 	INF("io",	S_IRUGO, proc_tid_io_accounting),
2975 #endif
2976 };
2977 
2978 static int proc_tid_base_readdir(struct file * filp,
2979 			     void * dirent, filldir_t filldir)
2980 {
2981 	return proc_pident_readdir(filp,dirent,filldir,
2982 				   tid_base_stuff,ARRAY_SIZE(tid_base_stuff));
2983 }
2984 
2985 static struct dentry *proc_tid_base_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd){
2986 	return proc_pident_lookup(dir, dentry,
2987 				  tid_base_stuff, ARRAY_SIZE(tid_base_stuff));
2988 }
2989 
2990 static const struct file_operations proc_tid_base_operations = {
2991 	.read		= generic_read_dir,
2992 	.readdir	= proc_tid_base_readdir,
2993 };
2994 
2995 static const struct inode_operations proc_tid_base_inode_operations = {
2996 	.lookup		= proc_tid_base_lookup,
2997 	.getattr	= pid_getattr,
2998 	.setattr	= proc_setattr,
2999 };
3000 
3001 static struct dentry *proc_task_instantiate(struct inode *dir,
3002 	struct dentry *dentry, struct task_struct *task, const void *ptr)
3003 {
3004 	struct dentry *error = ERR_PTR(-ENOENT);
3005 	struct inode *inode;
3006 	inode = proc_pid_make_inode(dir->i_sb, task);
3007 
3008 	if (!inode)
3009 		goto out;
3010 	inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
3011 	inode->i_op = &proc_tid_base_inode_operations;
3012 	inode->i_fop = &proc_tid_base_operations;
3013 	inode->i_flags|=S_IMMUTABLE;
3014 
3015 	inode->i_nlink = 2 + pid_entry_count_dirs(tid_base_stuff,
3016 		ARRAY_SIZE(tid_base_stuff));
3017 
3018 	dentry->d_op = &pid_dentry_operations;
3019 
3020 	d_add(dentry, inode);
3021 	/* Close the race of the process dying before we return the dentry */
3022 	if (pid_revalidate(dentry, NULL))
3023 		error = NULL;
3024 out:
3025 	return error;
3026 }
3027 
3028 static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd)
3029 {
3030 	struct dentry *result = ERR_PTR(-ENOENT);
3031 	struct task_struct *task;
3032 	struct task_struct *leader = get_proc_task(dir);
3033 	unsigned tid;
3034 	struct pid_namespace *ns;
3035 
3036 	if (!leader)
3037 		goto out_no_task;
3038 
3039 	tid = name_to_int(dentry);
3040 	if (tid == ~0U)
3041 		goto out;
3042 
3043 	ns = dentry->d_sb->s_fs_info;
3044 	rcu_read_lock();
3045 	task = find_task_by_pid_ns(tid, ns);
3046 	if (task)
3047 		get_task_struct(task);
3048 	rcu_read_unlock();
3049 	if (!task)
3050 		goto out;
3051 	if (!same_thread_group(leader, task))
3052 		goto out_drop_task;
3053 
3054 	result = proc_task_instantiate(dir, dentry, task, NULL);
3055 out_drop_task:
3056 	put_task_struct(task);
3057 out:
3058 	put_task_struct(leader);
3059 out_no_task:
3060 	return result;
3061 }
3062 
3063 /*
3064  * Find the first tid of a thread group to return to user space.
3065  *
3066  * Usually this is just the thread group leader, but if the users
3067  * buffer was too small or there was a seek into the middle of the
3068  * directory we have more work todo.
3069  *
3070  * In the case of a short read we start with find_task_by_pid.
3071  *
3072  * In the case of a seek we start with the leader and walk nr
3073  * threads past it.
3074  */
3075 static struct task_struct *first_tid(struct task_struct *leader,
3076 		int tid, int nr, struct pid_namespace *ns)
3077 {
3078 	struct task_struct *pos;
3079 
3080 	rcu_read_lock();
3081 	/* Attempt to start with the pid of a thread */
3082 	if (tid && (nr > 0)) {
3083 		pos = find_task_by_pid_ns(tid, ns);
3084 		if (pos && (pos->group_leader == leader))
3085 			goto found;
3086 	}
3087 
3088 	/* If nr exceeds the number of threads there is nothing todo */
3089 	pos = NULL;
3090 	if (nr && nr >= get_nr_threads(leader))
3091 		goto out;
3092 
3093 	/* If we haven't found our starting place yet start
3094 	 * with the leader and walk nr threads forward.
3095 	 */
3096 	for (pos = leader; nr > 0; --nr) {
3097 		pos = next_thread(pos);
3098 		if (pos == leader) {
3099 			pos = NULL;
3100 			goto out;
3101 		}
3102 	}
3103 found:
3104 	get_task_struct(pos);
3105 out:
3106 	rcu_read_unlock();
3107 	return pos;
3108 }
3109 
3110 /*
3111  * Find the next thread in the thread list.
3112  * Return NULL if there is an error or no next thread.
3113  *
3114  * The reference to the input task_struct is released.
3115  */
3116 static struct task_struct *next_tid(struct task_struct *start)
3117 {
3118 	struct task_struct *pos = NULL;
3119 	rcu_read_lock();
3120 	if (pid_alive(start)) {
3121 		pos = next_thread(start);
3122 		if (thread_group_leader(pos))
3123 			pos = NULL;
3124 		else
3125 			get_task_struct(pos);
3126 	}
3127 	rcu_read_unlock();
3128 	put_task_struct(start);
3129 	return pos;
3130 }
3131 
3132 static int proc_task_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
3133 	struct task_struct *task, int tid)
3134 {
3135 	char name[PROC_NUMBUF];
3136 	int len = snprintf(name, sizeof(name), "%d", tid);
3137 	return proc_fill_cache(filp, dirent, filldir, name, len,
3138 				proc_task_instantiate, task, NULL);
3139 }
3140 
3141 /* for the /proc/TGID/task/ directories */
3142 static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldir)
3143 {
3144 	struct dentry *dentry = filp->f_path.dentry;
3145 	struct inode *inode = dentry->d_inode;
3146 	struct task_struct *leader = NULL;
3147 	struct task_struct *task;
3148 	int retval = -ENOENT;
3149 	ino_t ino;
3150 	int tid;
3151 	struct pid_namespace *ns;
3152 
3153 	task = get_proc_task(inode);
3154 	if (!task)
3155 		goto out_no_task;
3156 	rcu_read_lock();
3157 	if (pid_alive(task)) {
3158 		leader = task->group_leader;
3159 		get_task_struct(leader);
3160 	}
3161 	rcu_read_unlock();
3162 	put_task_struct(task);
3163 	if (!leader)
3164 		goto out_no_task;
3165 	retval = 0;
3166 
3167 	switch ((unsigned long)filp->f_pos) {
3168 	case 0:
3169 		ino = inode->i_ino;
3170 		if (filldir(dirent, ".", 1, filp->f_pos, ino, DT_DIR) < 0)
3171 			goto out;
3172 		filp->f_pos++;
3173 		/* fall through */
3174 	case 1:
3175 		ino = parent_ino(dentry);
3176 		if (filldir(dirent, "..", 2, filp->f_pos, ino, DT_DIR) < 0)
3177 			goto out;
3178 		filp->f_pos++;
3179 		/* fall through */
3180 	}
3181 
3182 	/* f_version caches the tgid value that the last readdir call couldn't
3183 	 * return. lseek aka telldir automagically resets f_version to 0.
3184 	 */
3185 	ns = filp->f_dentry->d_sb->s_fs_info;
3186 	tid = (int)filp->f_version;
3187 	filp->f_version = 0;
3188 	for (task = first_tid(leader, tid, filp->f_pos - 2, ns);
3189 	     task;
3190 	     task = next_tid(task), filp->f_pos++) {
3191 		tid = task_pid_nr_ns(task, ns);
3192 		if (proc_task_fill_cache(filp, dirent, filldir, task, tid) < 0) {
3193 			/* returning this tgid failed, save it as the first
3194 			 * pid for the next readir call */
3195 			filp->f_version = (u64)tid;
3196 			put_task_struct(task);
3197 			break;
3198 		}
3199 	}
3200 out:
3201 	put_task_struct(leader);
3202 out_no_task:
3203 	return retval;
3204 }
3205 
3206 static int proc_task_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
3207 {
3208 	struct inode *inode = dentry->d_inode;
3209 	struct task_struct *p = get_proc_task(inode);
3210 	generic_fillattr(inode, stat);
3211 
3212 	if (p) {
3213 		stat->nlink += get_nr_threads(p);
3214 		put_task_struct(p);
3215 	}
3216 
3217 	return 0;
3218 }
3219 
3220 static const struct inode_operations proc_task_inode_operations = {
3221 	.lookup		= proc_task_lookup,
3222 	.getattr	= proc_task_getattr,
3223 	.setattr	= proc_setattr,
3224 };
3225 
3226 static const struct file_operations proc_task_operations = {
3227 	.read		= generic_read_dir,
3228 	.readdir	= proc_task_readdir,
3229 };
3230