xref: /openbmc/linux/fs/proc/base.c (revision ae3473231e77a3f1909d48cd144cebe5e1d049b3)
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 <linux/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/swap.h>
67 #include <linux/rcupdate.h>
68 #include <linux/kallsyms.h>
69 #include <linux/stacktrace.h>
70 #include <linux/resource.h>
71 #include <linux/module.h>
72 #include <linux/mount.h>
73 #include <linux/security.h>
74 #include <linux/ptrace.h>
75 #include <linux/tracehook.h>
76 #include <linux/printk.h>
77 #include <linux/cgroup.h>
78 #include <linux/cpuset.h>
79 #include <linux/audit.h>
80 #include <linux/poll.h>
81 #include <linux/nsproxy.h>
82 #include <linux/oom.h>
83 #include <linux/elf.h>
84 #include <linux/pid_namespace.h>
85 #include <linux/user_namespace.h>
86 #include <linux/fs_struct.h>
87 #include <linux/slab.h>
88 #include <linux/flex_array.h>
89 #include <linux/posix-timers.h>
90 #ifdef CONFIG_HARDWALL
91 #include <asm/hardwall.h>
92 #endif
93 #include <trace/events/oom.h>
94 #include "internal.h"
95 #include "fd.h"
96 
97 /* NOTE:
98  *	Implementing inode permission operations in /proc is almost
99  *	certainly an error.  Permission checks need to happen during
100  *	each system call not at open time.  The reason is that most of
101  *	what we wish to check for permissions in /proc varies at runtime.
102  *
103  *	The classic example of a problem is opening file descriptors
104  *	in /proc for a task before it execs a suid executable.
105  */
106 
107 static u8 nlink_tid;
108 static u8 nlink_tgid;
109 
110 struct pid_entry {
111 	const char *name;
112 	unsigned int len;
113 	umode_t mode;
114 	const struct inode_operations *iop;
115 	const struct file_operations *fop;
116 	union proc_op op;
117 };
118 
119 #define NOD(NAME, MODE, IOP, FOP, OP) {			\
120 	.name = (NAME),					\
121 	.len  = sizeof(NAME) - 1,			\
122 	.mode = MODE,					\
123 	.iop  = IOP,					\
124 	.fop  = FOP,					\
125 	.op   = OP,					\
126 }
127 
128 #define DIR(NAME, MODE, iops, fops)	\
129 	NOD(NAME, (S_IFDIR|(MODE)), &iops, &fops, {} )
130 #define LNK(NAME, get_link)					\
131 	NOD(NAME, (S_IFLNK|S_IRWXUGO),				\
132 		&proc_pid_link_inode_operations, NULL,		\
133 		{ .proc_get_link = get_link } )
134 #define REG(NAME, MODE, fops)				\
135 	NOD(NAME, (S_IFREG|(MODE)), NULL, &fops, {})
136 #define ONE(NAME, MODE, show)				\
137 	NOD(NAME, (S_IFREG|(MODE)), 			\
138 		NULL, &proc_single_file_operations,	\
139 		{ .proc_show = show } )
140 
141 /*
142  * Count the number of hardlinks for the pid_entry table, excluding the .
143  * and .. links.
144  */
145 static unsigned int __init pid_entry_nlink(const struct pid_entry *entries,
146 	unsigned int n)
147 {
148 	unsigned int i;
149 	unsigned int count;
150 
151 	count = 2;
152 	for (i = 0; i < n; ++i) {
153 		if (S_ISDIR(entries[i].mode))
154 			++count;
155 	}
156 
157 	return count;
158 }
159 
160 static int get_task_root(struct task_struct *task, struct path *root)
161 {
162 	int result = -ENOENT;
163 
164 	task_lock(task);
165 	if (task->fs) {
166 		get_fs_root(task->fs, root);
167 		result = 0;
168 	}
169 	task_unlock(task);
170 	return result;
171 }
172 
173 static int proc_cwd_link(struct dentry *dentry, struct path *path)
174 {
175 	struct task_struct *task = get_proc_task(d_inode(dentry));
176 	int result = -ENOENT;
177 
178 	if (task) {
179 		task_lock(task);
180 		if (task->fs) {
181 			get_fs_pwd(task->fs, path);
182 			result = 0;
183 		}
184 		task_unlock(task);
185 		put_task_struct(task);
186 	}
187 	return result;
188 }
189 
190 static int proc_root_link(struct dentry *dentry, struct path *path)
191 {
192 	struct task_struct *task = get_proc_task(d_inode(dentry));
193 	int result = -ENOENT;
194 
195 	if (task) {
196 		result = get_task_root(task, path);
197 		put_task_struct(task);
198 	}
199 	return result;
200 }
201 
202 static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
203 				     size_t _count, loff_t *pos)
204 {
205 	struct task_struct *tsk;
206 	struct mm_struct *mm;
207 	char *page;
208 	unsigned long count = _count;
209 	unsigned long arg_start, arg_end, env_start, env_end;
210 	unsigned long len1, len2, len;
211 	unsigned long p;
212 	char c;
213 	ssize_t rv;
214 
215 	BUG_ON(*pos < 0);
216 
217 	tsk = get_proc_task(file_inode(file));
218 	if (!tsk)
219 		return -ESRCH;
220 	mm = get_task_mm(tsk);
221 	put_task_struct(tsk);
222 	if (!mm)
223 		return 0;
224 	/* Check if process spawned far enough to have cmdline. */
225 	if (!mm->env_end) {
226 		rv = 0;
227 		goto out_mmput;
228 	}
229 
230 	page = (char *)__get_free_page(GFP_TEMPORARY);
231 	if (!page) {
232 		rv = -ENOMEM;
233 		goto out_mmput;
234 	}
235 
236 	down_read(&mm->mmap_sem);
237 	arg_start = mm->arg_start;
238 	arg_end = mm->arg_end;
239 	env_start = mm->env_start;
240 	env_end = mm->env_end;
241 	up_read(&mm->mmap_sem);
242 
243 	BUG_ON(arg_start > arg_end);
244 	BUG_ON(env_start > env_end);
245 
246 	len1 = arg_end - arg_start;
247 	len2 = env_end - env_start;
248 
249 	/* Empty ARGV. */
250 	if (len1 == 0) {
251 		rv = 0;
252 		goto out_free_page;
253 	}
254 	/*
255 	 * Inherently racy -- command line shares address space
256 	 * with code and data.
257 	 */
258 	rv = access_remote_vm(mm, arg_end - 1, &c, 1, 0);
259 	if (rv <= 0)
260 		goto out_free_page;
261 
262 	rv = 0;
263 
264 	if (c == '\0') {
265 		/* Command line (set of strings) occupies whole ARGV. */
266 		if (len1 <= *pos)
267 			goto out_free_page;
268 
269 		p = arg_start + *pos;
270 		len = len1 - *pos;
271 		while (count > 0 && len > 0) {
272 			unsigned int _count;
273 			int nr_read;
274 
275 			_count = min3(count, len, PAGE_SIZE);
276 			nr_read = access_remote_vm(mm, p, page, _count, 0);
277 			if (nr_read < 0)
278 				rv = nr_read;
279 			if (nr_read <= 0)
280 				goto out_free_page;
281 
282 			if (copy_to_user(buf, page, nr_read)) {
283 				rv = -EFAULT;
284 				goto out_free_page;
285 			}
286 
287 			p	+= nr_read;
288 			len	-= nr_read;
289 			buf	+= nr_read;
290 			count	-= nr_read;
291 			rv	+= nr_read;
292 		}
293 	} else {
294 		/*
295 		 * Command line (1 string) occupies ARGV and maybe
296 		 * extends into ENVP.
297 		 */
298 		if (len1 + len2 <= *pos)
299 			goto skip_argv_envp;
300 		if (len1 <= *pos)
301 			goto skip_argv;
302 
303 		p = arg_start + *pos;
304 		len = len1 - *pos;
305 		while (count > 0 && len > 0) {
306 			unsigned int _count, l;
307 			int nr_read;
308 			bool final;
309 
310 			_count = min3(count, len, PAGE_SIZE);
311 			nr_read = access_remote_vm(mm, p, page, _count, 0);
312 			if (nr_read < 0)
313 				rv = nr_read;
314 			if (nr_read <= 0)
315 				goto out_free_page;
316 
317 			/*
318 			 * Command line can be shorter than whole ARGV
319 			 * even if last "marker" byte says it is not.
320 			 */
321 			final = false;
322 			l = strnlen(page, nr_read);
323 			if (l < nr_read) {
324 				nr_read = l;
325 				final = true;
326 			}
327 
328 			if (copy_to_user(buf, page, nr_read)) {
329 				rv = -EFAULT;
330 				goto out_free_page;
331 			}
332 
333 			p	+= nr_read;
334 			len	-= nr_read;
335 			buf	+= nr_read;
336 			count	-= nr_read;
337 			rv	+= nr_read;
338 
339 			if (final)
340 				goto out_free_page;
341 		}
342 skip_argv:
343 		/*
344 		 * Command line (1 string) occupies ARGV and
345 		 * extends into ENVP.
346 		 */
347 		if (len1 <= *pos) {
348 			p = env_start + *pos - len1;
349 			len = len1 + len2 - *pos;
350 		} else {
351 			p = env_start;
352 			len = len2;
353 		}
354 		while (count > 0 && len > 0) {
355 			unsigned int _count, l;
356 			int nr_read;
357 			bool final;
358 
359 			_count = min3(count, len, PAGE_SIZE);
360 			nr_read = access_remote_vm(mm, p, page, _count, 0);
361 			if (nr_read < 0)
362 				rv = nr_read;
363 			if (nr_read <= 0)
364 				goto out_free_page;
365 
366 			/* Find EOS. */
367 			final = false;
368 			l = strnlen(page, nr_read);
369 			if (l < nr_read) {
370 				nr_read = l;
371 				final = true;
372 			}
373 
374 			if (copy_to_user(buf, page, nr_read)) {
375 				rv = -EFAULT;
376 				goto out_free_page;
377 			}
378 
379 			p	+= nr_read;
380 			len	-= nr_read;
381 			buf	+= nr_read;
382 			count	-= nr_read;
383 			rv	+= nr_read;
384 
385 			if (final)
386 				goto out_free_page;
387 		}
388 skip_argv_envp:
389 		;
390 	}
391 
392 out_free_page:
393 	free_page((unsigned long)page);
394 out_mmput:
395 	mmput(mm);
396 	if (rv > 0)
397 		*pos += rv;
398 	return rv;
399 }
400 
401 static const struct file_operations proc_pid_cmdline_ops = {
402 	.read	= proc_pid_cmdline_read,
403 	.llseek	= generic_file_llseek,
404 };
405 
406 #ifdef CONFIG_KALLSYMS
407 /*
408  * Provides a wchan file via kallsyms in a proper one-value-per-file format.
409  * Returns the resolved symbol.  If that fails, simply return the address.
410  */
411 static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns,
412 			  struct pid *pid, struct task_struct *task)
413 {
414 	unsigned long wchan;
415 	char symname[KSYM_NAME_LEN];
416 
417 	wchan = get_wchan(task);
418 
419 	if (wchan && ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)
420 			&& !lookup_symbol_name(wchan, symname))
421 		seq_printf(m, "%s", symname);
422 	else
423 		seq_putc(m, '0');
424 
425 	return 0;
426 }
427 #endif /* CONFIG_KALLSYMS */
428 
429 static int lock_trace(struct task_struct *task)
430 {
431 	int err = mutex_lock_killable(&task->signal->cred_guard_mutex);
432 	if (err)
433 		return err;
434 	if (!ptrace_may_access(task, PTRACE_MODE_ATTACH_FSCREDS)) {
435 		mutex_unlock(&task->signal->cred_guard_mutex);
436 		return -EPERM;
437 	}
438 	return 0;
439 }
440 
441 static void unlock_trace(struct task_struct *task)
442 {
443 	mutex_unlock(&task->signal->cred_guard_mutex);
444 }
445 
446 #ifdef CONFIG_STACKTRACE
447 
448 #define MAX_STACK_TRACE_DEPTH	64
449 
450 static int proc_pid_stack(struct seq_file *m, struct pid_namespace *ns,
451 			  struct pid *pid, struct task_struct *task)
452 {
453 	struct stack_trace trace;
454 	unsigned long *entries;
455 	int err;
456 	int i;
457 
458 	entries = kmalloc(MAX_STACK_TRACE_DEPTH * sizeof(*entries), GFP_KERNEL);
459 	if (!entries)
460 		return -ENOMEM;
461 
462 	trace.nr_entries	= 0;
463 	trace.max_entries	= MAX_STACK_TRACE_DEPTH;
464 	trace.entries		= entries;
465 	trace.skip		= 0;
466 
467 	err = lock_trace(task);
468 	if (!err) {
469 		save_stack_trace_tsk(task, &trace);
470 
471 		for (i = 0; i < trace.nr_entries; i++) {
472 			seq_printf(m, "[<%pK>] %pB\n",
473 				   (void *)entries[i], (void *)entries[i]);
474 		}
475 		unlock_trace(task);
476 	}
477 	kfree(entries);
478 
479 	return err;
480 }
481 #endif
482 
483 #ifdef CONFIG_SCHED_INFO
484 /*
485  * Provides /proc/PID/schedstat
486  */
487 static int proc_pid_schedstat(struct seq_file *m, struct pid_namespace *ns,
488 			      struct pid *pid, struct task_struct *task)
489 {
490 	if (unlikely(!sched_info_on()))
491 		seq_printf(m, "0 0 0\n");
492 	else
493 		seq_printf(m, "%llu %llu %lu\n",
494 		   (unsigned long long)task->se.sum_exec_runtime,
495 		   (unsigned long long)task->sched_info.run_delay,
496 		   task->sched_info.pcount);
497 
498 	return 0;
499 }
500 #endif
501 
502 #ifdef CONFIG_LATENCYTOP
503 static int lstats_show_proc(struct seq_file *m, void *v)
504 {
505 	int i;
506 	struct inode *inode = m->private;
507 	struct task_struct *task = get_proc_task(inode);
508 
509 	if (!task)
510 		return -ESRCH;
511 	seq_puts(m, "Latency Top version : v0.1\n");
512 	for (i = 0; i < 32; i++) {
513 		struct latency_record *lr = &task->latency_record[i];
514 		if (lr->backtrace[0]) {
515 			int q;
516 			seq_printf(m, "%i %li %li",
517 				   lr->count, lr->time, lr->max);
518 			for (q = 0; q < LT_BACKTRACEDEPTH; q++) {
519 				unsigned long bt = lr->backtrace[q];
520 				if (!bt)
521 					break;
522 				if (bt == ULONG_MAX)
523 					break;
524 				seq_printf(m, " %ps", (void *)bt);
525 			}
526 			seq_putc(m, '\n');
527 		}
528 
529 	}
530 	put_task_struct(task);
531 	return 0;
532 }
533 
534 static int lstats_open(struct inode *inode, struct file *file)
535 {
536 	return single_open(file, lstats_show_proc, inode);
537 }
538 
539 static ssize_t lstats_write(struct file *file, const char __user *buf,
540 			    size_t count, loff_t *offs)
541 {
542 	struct task_struct *task = get_proc_task(file_inode(file));
543 
544 	if (!task)
545 		return -ESRCH;
546 	clear_all_latency_tracing(task);
547 	put_task_struct(task);
548 
549 	return count;
550 }
551 
552 static const struct file_operations proc_lstats_operations = {
553 	.open		= lstats_open,
554 	.read		= seq_read,
555 	.write		= lstats_write,
556 	.llseek		= seq_lseek,
557 	.release	= single_release,
558 };
559 
560 #endif
561 
562 static int proc_oom_score(struct seq_file *m, struct pid_namespace *ns,
563 			  struct pid *pid, struct task_struct *task)
564 {
565 	unsigned long totalpages = totalram_pages + total_swap_pages;
566 	unsigned long points = 0;
567 
568 	points = oom_badness(task, NULL, NULL, totalpages) *
569 					1000 / totalpages;
570 	seq_printf(m, "%lu\n", points);
571 
572 	return 0;
573 }
574 
575 struct limit_names {
576 	const char *name;
577 	const char *unit;
578 };
579 
580 static const struct limit_names lnames[RLIM_NLIMITS] = {
581 	[RLIMIT_CPU] = {"Max cpu time", "seconds"},
582 	[RLIMIT_FSIZE] = {"Max file size", "bytes"},
583 	[RLIMIT_DATA] = {"Max data size", "bytes"},
584 	[RLIMIT_STACK] = {"Max stack size", "bytes"},
585 	[RLIMIT_CORE] = {"Max core file size", "bytes"},
586 	[RLIMIT_RSS] = {"Max resident set", "bytes"},
587 	[RLIMIT_NPROC] = {"Max processes", "processes"},
588 	[RLIMIT_NOFILE] = {"Max open files", "files"},
589 	[RLIMIT_MEMLOCK] = {"Max locked memory", "bytes"},
590 	[RLIMIT_AS] = {"Max address space", "bytes"},
591 	[RLIMIT_LOCKS] = {"Max file locks", "locks"},
592 	[RLIMIT_SIGPENDING] = {"Max pending signals", "signals"},
593 	[RLIMIT_MSGQUEUE] = {"Max msgqueue size", "bytes"},
594 	[RLIMIT_NICE] = {"Max nice priority", NULL},
595 	[RLIMIT_RTPRIO] = {"Max realtime priority", NULL},
596 	[RLIMIT_RTTIME] = {"Max realtime timeout", "us"},
597 };
598 
599 /* Display limits for a process */
600 static int proc_pid_limits(struct seq_file *m, struct pid_namespace *ns,
601 			   struct pid *pid, struct task_struct *task)
602 {
603 	unsigned int i;
604 	unsigned long flags;
605 
606 	struct rlimit rlim[RLIM_NLIMITS];
607 
608 	if (!lock_task_sighand(task, &flags))
609 		return 0;
610 	memcpy(rlim, task->signal->rlim, sizeof(struct rlimit) * RLIM_NLIMITS);
611 	unlock_task_sighand(task, &flags);
612 
613 	/*
614 	 * print the file header
615 	 */
616        seq_printf(m, "%-25s %-20s %-20s %-10s\n",
617 		  "Limit", "Soft Limit", "Hard Limit", "Units");
618 
619 	for (i = 0; i < RLIM_NLIMITS; i++) {
620 		if (rlim[i].rlim_cur == RLIM_INFINITY)
621 			seq_printf(m, "%-25s %-20s ",
622 				   lnames[i].name, "unlimited");
623 		else
624 			seq_printf(m, "%-25s %-20lu ",
625 				   lnames[i].name, rlim[i].rlim_cur);
626 
627 		if (rlim[i].rlim_max == RLIM_INFINITY)
628 			seq_printf(m, "%-20s ", "unlimited");
629 		else
630 			seq_printf(m, "%-20lu ", rlim[i].rlim_max);
631 
632 		if (lnames[i].unit)
633 			seq_printf(m, "%-10s\n", lnames[i].unit);
634 		else
635 			seq_putc(m, '\n');
636 	}
637 
638 	return 0;
639 }
640 
641 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
642 static int proc_pid_syscall(struct seq_file *m, struct pid_namespace *ns,
643 			    struct pid *pid, struct task_struct *task)
644 {
645 	long nr;
646 	unsigned long args[6], sp, pc;
647 	int res;
648 
649 	res = lock_trace(task);
650 	if (res)
651 		return res;
652 
653 	if (task_current_syscall(task, &nr, args, 6, &sp, &pc))
654 		seq_puts(m, "running\n");
655 	else if (nr < 0)
656 		seq_printf(m, "%ld 0x%lx 0x%lx\n", nr, sp, pc);
657 	else
658 		seq_printf(m,
659 		       "%ld 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx\n",
660 		       nr,
661 		       args[0], args[1], args[2], args[3], args[4], args[5],
662 		       sp, pc);
663 	unlock_trace(task);
664 
665 	return 0;
666 }
667 #endif /* CONFIG_HAVE_ARCH_TRACEHOOK */
668 
669 /************************************************************************/
670 /*                       Here the fs part begins                        */
671 /************************************************************************/
672 
673 /* permission checks */
674 static int proc_fd_access_allowed(struct inode *inode)
675 {
676 	struct task_struct *task;
677 	int allowed = 0;
678 	/* Allow access to a task's file descriptors if it is us or we
679 	 * may use ptrace attach to the process and find out that
680 	 * information.
681 	 */
682 	task = get_proc_task(inode);
683 	if (task) {
684 		allowed = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
685 		put_task_struct(task);
686 	}
687 	return allowed;
688 }
689 
690 int proc_setattr(struct dentry *dentry, struct iattr *attr)
691 {
692 	int error;
693 	struct inode *inode = d_inode(dentry);
694 
695 	if (attr->ia_valid & ATTR_MODE)
696 		return -EPERM;
697 
698 	error = setattr_prepare(dentry, attr);
699 	if (error)
700 		return error;
701 
702 	setattr_copy(inode, attr);
703 	mark_inode_dirty(inode);
704 	return 0;
705 }
706 
707 /*
708  * May current process learn task's sched/cmdline info (for hide_pid_min=1)
709  * or euid/egid (for hide_pid_min=2)?
710  */
711 static bool has_pid_permissions(struct pid_namespace *pid,
712 				 struct task_struct *task,
713 				 int hide_pid_min)
714 {
715 	if (pid->hide_pid < hide_pid_min)
716 		return true;
717 	if (in_group_p(pid->pid_gid))
718 		return true;
719 	return ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
720 }
721 
722 
723 static int proc_pid_permission(struct inode *inode, int mask)
724 {
725 	struct pid_namespace *pid = inode->i_sb->s_fs_info;
726 	struct task_struct *task;
727 	bool has_perms;
728 
729 	task = get_proc_task(inode);
730 	if (!task)
731 		return -ESRCH;
732 	has_perms = has_pid_permissions(pid, task, 1);
733 	put_task_struct(task);
734 
735 	if (!has_perms) {
736 		if (pid->hide_pid == 2) {
737 			/*
738 			 * Let's make getdents(), stat(), and open()
739 			 * consistent with each other.  If a process
740 			 * may not stat() a file, it shouldn't be seen
741 			 * in procfs at all.
742 			 */
743 			return -ENOENT;
744 		}
745 
746 		return -EPERM;
747 	}
748 	return generic_permission(inode, mask);
749 }
750 
751 
752 
753 static const struct inode_operations proc_def_inode_operations = {
754 	.setattr	= proc_setattr,
755 };
756 
757 static int proc_single_show(struct seq_file *m, void *v)
758 {
759 	struct inode *inode = m->private;
760 	struct pid_namespace *ns;
761 	struct pid *pid;
762 	struct task_struct *task;
763 	int ret;
764 
765 	ns = inode->i_sb->s_fs_info;
766 	pid = proc_pid(inode);
767 	task = get_pid_task(pid, PIDTYPE_PID);
768 	if (!task)
769 		return -ESRCH;
770 
771 	ret = PROC_I(inode)->op.proc_show(m, ns, pid, task);
772 
773 	put_task_struct(task);
774 	return ret;
775 }
776 
777 static int proc_single_open(struct inode *inode, struct file *filp)
778 {
779 	return single_open(filp, proc_single_show, inode);
780 }
781 
782 static const struct file_operations proc_single_file_operations = {
783 	.open		= proc_single_open,
784 	.read		= seq_read,
785 	.llseek		= seq_lseek,
786 	.release	= single_release,
787 };
788 
789 
790 struct mm_struct *proc_mem_open(struct inode *inode, unsigned int mode)
791 {
792 	struct task_struct *task = get_proc_task(inode);
793 	struct mm_struct *mm = ERR_PTR(-ESRCH);
794 
795 	if (task) {
796 		mm = mm_access(task, mode | PTRACE_MODE_FSCREDS);
797 		put_task_struct(task);
798 
799 		if (!IS_ERR_OR_NULL(mm)) {
800 			/* ensure this mm_struct can't be freed */
801 			atomic_inc(&mm->mm_count);
802 			/* but do not pin its memory */
803 			mmput(mm);
804 		}
805 	}
806 
807 	return mm;
808 }
809 
810 static int __mem_open(struct inode *inode, struct file *file, unsigned int mode)
811 {
812 	struct mm_struct *mm = proc_mem_open(inode, mode);
813 
814 	if (IS_ERR(mm))
815 		return PTR_ERR(mm);
816 
817 	file->private_data = mm;
818 	return 0;
819 }
820 
821 static int mem_open(struct inode *inode, struct file *file)
822 {
823 	int ret = __mem_open(inode, file, PTRACE_MODE_ATTACH);
824 
825 	/* OK to pass negative loff_t, we can catch out-of-range */
826 	file->f_mode |= FMODE_UNSIGNED_OFFSET;
827 
828 	return ret;
829 }
830 
831 static ssize_t mem_rw(struct file *file, char __user *buf,
832 			size_t count, loff_t *ppos, int write)
833 {
834 	struct mm_struct *mm = file->private_data;
835 	unsigned long addr = *ppos;
836 	ssize_t copied;
837 	char *page;
838 	unsigned int flags;
839 
840 	if (!mm)
841 		return 0;
842 
843 	page = (char *)__get_free_page(GFP_TEMPORARY);
844 	if (!page)
845 		return -ENOMEM;
846 
847 	copied = 0;
848 	if (!atomic_inc_not_zero(&mm->mm_users))
849 		goto free;
850 
851 	/* Maybe we should limit FOLL_FORCE to actual ptrace users? */
852 	flags = FOLL_FORCE;
853 	if (write)
854 		flags |= FOLL_WRITE;
855 
856 	while (count > 0) {
857 		int this_len = min_t(int, count, PAGE_SIZE);
858 
859 		if (write && copy_from_user(page, buf, this_len)) {
860 			copied = -EFAULT;
861 			break;
862 		}
863 
864 		this_len = access_remote_vm(mm, addr, page, this_len, flags);
865 		if (!this_len) {
866 			if (!copied)
867 				copied = -EIO;
868 			break;
869 		}
870 
871 		if (!write && copy_to_user(buf, page, this_len)) {
872 			copied = -EFAULT;
873 			break;
874 		}
875 
876 		buf += this_len;
877 		addr += this_len;
878 		copied += this_len;
879 		count -= this_len;
880 	}
881 	*ppos = addr;
882 
883 	mmput(mm);
884 free:
885 	free_page((unsigned long) page);
886 	return copied;
887 }
888 
889 static ssize_t mem_read(struct file *file, char __user *buf,
890 			size_t count, loff_t *ppos)
891 {
892 	return mem_rw(file, buf, count, ppos, 0);
893 }
894 
895 static ssize_t mem_write(struct file *file, const char __user *buf,
896 			 size_t count, loff_t *ppos)
897 {
898 	return mem_rw(file, (char __user*)buf, count, ppos, 1);
899 }
900 
901 loff_t mem_lseek(struct file *file, loff_t offset, int orig)
902 {
903 	switch (orig) {
904 	case 0:
905 		file->f_pos = offset;
906 		break;
907 	case 1:
908 		file->f_pos += offset;
909 		break;
910 	default:
911 		return -EINVAL;
912 	}
913 	force_successful_syscall_return();
914 	return file->f_pos;
915 }
916 
917 static int mem_release(struct inode *inode, struct file *file)
918 {
919 	struct mm_struct *mm = file->private_data;
920 	if (mm)
921 		mmdrop(mm);
922 	return 0;
923 }
924 
925 static const struct file_operations proc_mem_operations = {
926 	.llseek		= mem_lseek,
927 	.read		= mem_read,
928 	.write		= mem_write,
929 	.open		= mem_open,
930 	.release	= mem_release,
931 };
932 
933 static int environ_open(struct inode *inode, struct file *file)
934 {
935 	return __mem_open(inode, file, PTRACE_MODE_READ);
936 }
937 
938 static ssize_t environ_read(struct file *file, char __user *buf,
939 			size_t count, loff_t *ppos)
940 {
941 	char *page;
942 	unsigned long src = *ppos;
943 	int ret = 0;
944 	struct mm_struct *mm = file->private_data;
945 	unsigned long env_start, env_end;
946 
947 	/* Ensure the process spawned far enough to have an environment. */
948 	if (!mm || !mm->env_end)
949 		return 0;
950 
951 	page = (char *)__get_free_page(GFP_TEMPORARY);
952 	if (!page)
953 		return -ENOMEM;
954 
955 	ret = 0;
956 	if (!atomic_inc_not_zero(&mm->mm_users))
957 		goto free;
958 
959 	down_read(&mm->mmap_sem);
960 	env_start = mm->env_start;
961 	env_end = mm->env_end;
962 	up_read(&mm->mmap_sem);
963 
964 	while (count > 0) {
965 		size_t this_len, max_len;
966 		int retval;
967 
968 		if (src >= (env_end - env_start))
969 			break;
970 
971 		this_len = env_end - (env_start + src);
972 
973 		max_len = min_t(size_t, PAGE_SIZE, count);
974 		this_len = min(max_len, this_len);
975 
976 		retval = access_remote_vm(mm, (env_start + src), page, this_len, 0);
977 
978 		if (retval <= 0) {
979 			ret = retval;
980 			break;
981 		}
982 
983 		if (copy_to_user(buf, page, retval)) {
984 			ret = -EFAULT;
985 			break;
986 		}
987 
988 		ret += retval;
989 		src += retval;
990 		buf += retval;
991 		count -= retval;
992 	}
993 	*ppos = src;
994 	mmput(mm);
995 
996 free:
997 	free_page((unsigned long) page);
998 	return ret;
999 }
1000 
1001 static const struct file_operations proc_environ_operations = {
1002 	.open		= environ_open,
1003 	.read		= environ_read,
1004 	.llseek		= generic_file_llseek,
1005 	.release	= mem_release,
1006 };
1007 
1008 static int auxv_open(struct inode *inode, struct file *file)
1009 {
1010 	return __mem_open(inode, file, PTRACE_MODE_READ_FSCREDS);
1011 }
1012 
1013 static ssize_t auxv_read(struct file *file, char __user *buf,
1014 			size_t count, loff_t *ppos)
1015 {
1016 	struct mm_struct *mm = file->private_data;
1017 	unsigned int nwords = 0;
1018 
1019 	if (!mm)
1020 		return 0;
1021 	do {
1022 		nwords += 2;
1023 	} while (mm->saved_auxv[nwords - 2] != 0); /* AT_NULL */
1024 	return simple_read_from_buffer(buf, count, ppos, mm->saved_auxv,
1025 				       nwords * sizeof(mm->saved_auxv[0]));
1026 }
1027 
1028 static const struct file_operations proc_auxv_operations = {
1029 	.open		= auxv_open,
1030 	.read		= auxv_read,
1031 	.llseek		= generic_file_llseek,
1032 	.release	= mem_release,
1033 };
1034 
1035 static ssize_t oom_adj_read(struct file *file, char __user *buf, size_t count,
1036 			    loff_t *ppos)
1037 {
1038 	struct task_struct *task = get_proc_task(file_inode(file));
1039 	char buffer[PROC_NUMBUF];
1040 	int oom_adj = OOM_ADJUST_MIN;
1041 	size_t len;
1042 
1043 	if (!task)
1044 		return -ESRCH;
1045 	if (task->signal->oom_score_adj == OOM_SCORE_ADJ_MAX)
1046 		oom_adj = OOM_ADJUST_MAX;
1047 	else
1048 		oom_adj = (task->signal->oom_score_adj * -OOM_DISABLE) /
1049 			  OOM_SCORE_ADJ_MAX;
1050 	put_task_struct(task);
1051 	len = snprintf(buffer, sizeof(buffer), "%d\n", oom_adj);
1052 	return simple_read_from_buffer(buf, count, ppos, buffer, len);
1053 }
1054 
1055 static int __set_oom_adj(struct file *file, int oom_adj, bool legacy)
1056 {
1057 	static DEFINE_MUTEX(oom_adj_mutex);
1058 	struct mm_struct *mm = NULL;
1059 	struct task_struct *task;
1060 	int err = 0;
1061 
1062 	task = get_proc_task(file_inode(file));
1063 	if (!task)
1064 		return -ESRCH;
1065 
1066 	mutex_lock(&oom_adj_mutex);
1067 	if (legacy) {
1068 		if (oom_adj < task->signal->oom_score_adj &&
1069 				!capable(CAP_SYS_RESOURCE)) {
1070 			err = -EACCES;
1071 			goto err_unlock;
1072 		}
1073 		/*
1074 		 * /proc/pid/oom_adj is provided for legacy purposes, ask users to use
1075 		 * /proc/pid/oom_score_adj instead.
1076 		 */
1077 		pr_warn_once("%s (%d): /proc/%d/oom_adj is deprecated, please use /proc/%d/oom_score_adj instead.\n",
1078 			  current->comm, task_pid_nr(current), task_pid_nr(task),
1079 			  task_pid_nr(task));
1080 	} else {
1081 		if ((short)oom_adj < task->signal->oom_score_adj_min &&
1082 				!capable(CAP_SYS_RESOURCE)) {
1083 			err = -EACCES;
1084 			goto err_unlock;
1085 		}
1086 	}
1087 
1088 	/*
1089 	 * Make sure we will check other processes sharing the mm if this is
1090 	 * not vfrok which wants its own oom_score_adj.
1091 	 * pin the mm so it doesn't go away and get reused after task_unlock
1092 	 */
1093 	if (!task->vfork_done) {
1094 		struct task_struct *p = find_lock_task_mm(task);
1095 
1096 		if (p) {
1097 			if (atomic_read(&p->mm->mm_users) > 1) {
1098 				mm = p->mm;
1099 				atomic_inc(&mm->mm_count);
1100 			}
1101 			task_unlock(p);
1102 		}
1103 	}
1104 
1105 	task->signal->oom_score_adj = oom_adj;
1106 	if (!legacy && has_capability_noaudit(current, CAP_SYS_RESOURCE))
1107 		task->signal->oom_score_adj_min = (short)oom_adj;
1108 	trace_oom_score_adj_update(task);
1109 
1110 	if (mm) {
1111 		struct task_struct *p;
1112 
1113 		rcu_read_lock();
1114 		for_each_process(p) {
1115 			if (same_thread_group(task, p))
1116 				continue;
1117 
1118 			/* do not touch kernel threads or the global init */
1119 			if (p->flags & PF_KTHREAD || is_global_init(p))
1120 				continue;
1121 
1122 			task_lock(p);
1123 			if (!p->vfork_done && process_shares_mm(p, mm)) {
1124 				pr_info("updating oom_score_adj for %d (%s) from %d to %d because it shares mm with %d (%s). Report if this is unexpected.\n",
1125 						task_pid_nr(p), p->comm,
1126 						p->signal->oom_score_adj, oom_adj,
1127 						task_pid_nr(task), task->comm);
1128 				p->signal->oom_score_adj = oom_adj;
1129 				if (!legacy && has_capability_noaudit(current, CAP_SYS_RESOURCE))
1130 					p->signal->oom_score_adj_min = (short)oom_adj;
1131 			}
1132 			task_unlock(p);
1133 		}
1134 		rcu_read_unlock();
1135 		mmdrop(mm);
1136 	}
1137 err_unlock:
1138 	mutex_unlock(&oom_adj_mutex);
1139 	put_task_struct(task);
1140 	return err;
1141 }
1142 
1143 /*
1144  * /proc/pid/oom_adj exists solely for backwards compatibility with previous
1145  * kernels.  The effective policy is defined by oom_score_adj, which has a
1146  * different scale: oom_adj grew exponentially and oom_score_adj grows linearly.
1147  * Values written to oom_adj are simply mapped linearly to oom_score_adj.
1148  * Processes that become oom disabled via oom_adj will still be oom disabled
1149  * with this implementation.
1150  *
1151  * oom_adj cannot be removed since existing userspace binaries use it.
1152  */
1153 static ssize_t oom_adj_write(struct file *file, const char __user *buf,
1154 			     size_t count, loff_t *ppos)
1155 {
1156 	char buffer[PROC_NUMBUF];
1157 	int oom_adj;
1158 	int err;
1159 
1160 	memset(buffer, 0, sizeof(buffer));
1161 	if (count > sizeof(buffer) - 1)
1162 		count = sizeof(buffer) - 1;
1163 	if (copy_from_user(buffer, buf, count)) {
1164 		err = -EFAULT;
1165 		goto out;
1166 	}
1167 
1168 	err = kstrtoint(strstrip(buffer), 0, &oom_adj);
1169 	if (err)
1170 		goto out;
1171 	if ((oom_adj < OOM_ADJUST_MIN || oom_adj > OOM_ADJUST_MAX) &&
1172 	     oom_adj != OOM_DISABLE) {
1173 		err = -EINVAL;
1174 		goto out;
1175 	}
1176 
1177 	/*
1178 	 * Scale /proc/pid/oom_score_adj appropriately ensuring that a maximum
1179 	 * value is always attainable.
1180 	 */
1181 	if (oom_adj == OOM_ADJUST_MAX)
1182 		oom_adj = OOM_SCORE_ADJ_MAX;
1183 	else
1184 		oom_adj = (oom_adj * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE;
1185 
1186 	err = __set_oom_adj(file, oom_adj, true);
1187 out:
1188 	return err < 0 ? err : count;
1189 }
1190 
1191 static const struct file_operations proc_oom_adj_operations = {
1192 	.read		= oom_adj_read,
1193 	.write		= oom_adj_write,
1194 	.llseek		= generic_file_llseek,
1195 };
1196 
1197 static ssize_t oom_score_adj_read(struct file *file, char __user *buf,
1198 					size_t count, loff_t *ppos)
1199 {
1200 	struct task_struct *task = get_proc_task(file_inode(file));
1201 	char buffer[PROC_NUMBUF];
1202 	short oom_score_adj = OOM_SCORE_ADJ_MIN;
1203 	size_t len;
1204 
1205 	if (!task)
1206 		return -ESRCH;
1207 	oom_score_adj = task->signal->oom_score_adj;
1208 	put_task_struct(task);
1209 	len = snprintf(buffer, sizeof(buffer), "%hd\n", oom_score_adj);
1210 	return simple_read_from_buffer(buf, count, ppos, buffer, len);
1211 }
1212 
1213 static ssize_t oom_score_adj_write(struct file *file, const char __user *buf,
1214 					size_t count, loff_t *ppos)
1215 {
1216 	char buffer[PROC_NUMBUF];
1217 	int oom_score_adj;
1218 	int err;
1219 
1220 	memset(buffer, 0, sizeof(buffer));
1221 	if (count > sizeof(buffer) - 1)
1222 		count = sizeof(buffer) - 1;
1223 	if (copy_from_user(buffer, buf, count)) {
1224 		err = -EFAULT;
1225 		goto out;
1226 	}
1227 
1228 	err = kstrtoint(strstrip(buffer), 0, &oom_score_adj);
1229 	if (err)
1230 		goto out;
1231 	if (oom_score_adj < OOM_SCORE_ADJ_MIN ||
1232 			oom_score_adj > OOM_SCORE_ADJ_MAX) {
1233 		err = -EINVAL;
1234 		goto out;
1235 	}
1236 
1237 	err = __set_oom_adj(file, oom_score_adj, false);
1238 out:
1239 	return err < 0 ? err : count;
1240 }
1241 
1242 static const struct file_operations proc_oom_score_adj_operations = {
1243 	.read		= oom_score_adj_read,
1244 	.write		= oom_score_adj_write,
1245 	.llseek		= default_llseek,
1246 };
1247 
1248 #ifdef CONFIG_AUDITSYSCALL
1249 #define TMPBUFLEN 11
1250 static ssize_t proc_loginuid_read(struct file * file, char __user * buf,
1251 				  size_t count, loff_t *ppos)
1252 {
1253 	struct inode * inode = file_inode(file);
1254 	struct task_struct *task = get_proc_task(inode);
1255 	ssize_t length;
1256 	char tmpbuf[TMPBUFLEN];
1257 
1258 	if (!task)
1259 		return -ESRCH;
1260 	length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
1261 			   from_kuid(file->f_cred->user_ns,
1262 				     audit_get_loginuid(task)));
1263 	put_task_struct(task);
1264 	return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
1265 }
1266 
1267 static ssize_t proc_loginuid_write(struct file * file, const char __user * buf,
1268 				   size_t count, loff_t *ppos)
1269 {
1270 	struct inode * inode = file_inode(file);
1271 	uid_t loginuid;
1272 	kuid_t kloginuid;
1273 	int rv;
1274 
1275 	rcu_read_lock();
1276 	if (current != pid_task(proc_pid(inode), PIDTYPE_PID)) {
1277 		rcu_read_unlock();
1278 		return -EPERM;
1279 	}
1280 	rcu_read_unlock();
1281 
1282 	if (*ppos != 0) {
1283 		/* No partial writes. */
1284 		return -EINVAL;
1285 	}
1286 
1287 	rv = kstrtou32_from_user(buf, count, 10, &loginuid);
1288 	if (rv < 0)
1289 		return rv;
1290 
1291 	/* is userspace tring to explicitly UNSET the loginuid? */
1292 	if (loginuid == AUDIT_UID_UNSET) {
1293 		kloginuid = INVALID_UID;
1294 	} else {
1295 		kloginuid = make_kuid(file->f_cred->user_ns, loginuid);
1296 		if (!uid_valid(kloginuid))
1297 			return -EINVAL;
1298 	}
1299 
1300 	rv = audit_set_loginuid(kloginuid);
1301 	if (rv < 0)
1302 		return rv;
1303 	return count;
1304 }
1305 
1306 static const struct file_operations proc_loginuid_operations = {
1307 	.read		= proc_loginuid_read,
1308 	.write		= proc_loginuid_write,
1309 	.llseek		= generic_file_llseek,
1310 };
1311 
1312 static ssize_t proc_sessionid_read(struct file * file, char __user * buf,
1313 				  size_t count, loff_t *ppos)
1314 {
1315 	struct inode * inode = file_inode(file);
1316 	struct task_struct *task = get_proc_task(inode);
1317 	ssize_t length;
1318 	char tmpbuf[TMPBUFLEN];
1319 
1320 	if (!task)
1321 		return -ESRCH;
1322 	length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
1323 				audit_get_sessionid(task));
1324 	put_task_struct(task);
1325 	return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
1326 }
1327 
1328 static const struct file_operations proc_sessionid_operations = {
1329 	.read		= proc_sessionid_read,
1330 	.llseek		= generic_file_llseek,
1331 };
1332 #endif
1333 
1334 #ifdef CONFIG_FAULT_INJECTION
1335 static ssize_t proc_fault_inject_read(struct file * file, char __user * buf,
1336 				      size_t count, loff_t *ppos)
1337 {
1338 	struct task_struct *task = get_proc_task(file_inode(file));
1339 	char buffer[PROC_NUMBUF];
1340 	size_t len;
1341 	int make_it_fail;
1342 
1343 	if (!task)
1344 		return -ESRCH;
1345 	make_it_fail = task->make_it_fail;
1346 	put_task_struct(task);
1347 
1348 	len = snprintf(buffer, sizeof(buffer), "%i\n", make_it_fail);
1349 
1350 	return simple_read_from_buffer(buf, count, ppos, buffer, len);
1351 }
1352 
1353 static ssize_t proc_fault_inject_write(struct file * file,
1354 			const char __user * buf, size_t count, loff_t *ppos)
1355 {
1356 	struct task_struct *task;
1357 	char buffer[PROC_NUMBUF];
1358 	int make_it_fail;
1359 	int rv;
1360 
1361 	if (!capable(CAP_SYS_RESOURCE))
1362 		return -EPERM;
1363 	memset(buffer, 0, sizeof(buffer));
1364 	if (count > sizeof(buffer) - 1)
1365 		count = sizeof(buffer) - 1;
1366 	if (copy_from_user(buffer, buf, count))
1367 		return -EFAULT;
1368 	rv = kstrtoint(strstrip(buffer), 0, &make_it_fail);
1369 	if (rv < 0)
1370 		return rv;
1371 	if (make_it_fail < 0 || make_it_fail > 1)
1372 		return -EINVAL;
1373 
1374 	task = get_proc_task(file_inode(file));
1375 	if (!task)
1376 		return -ESRCH;
1377 	task->make_it_fail = make_it_fail;
1378 	put_task_struct(task);
1379 
1380 	return count;
1381 }
1382 
1383 static const struct file_operations proc_fault_inject_operations = {
1384 	.read		= proc_fault_inject_read,
1385 	.write		= proc_fault_inject_write,
1386 	.llseek		= generic_file_llseek,
1387 };
1388 #endif
1389 
1390 
1391 #ifdef CONFIG_SCHED_DEBUG
1392 /*
1393  * Print out various scheduling related per-task fields:
1394  */
1395 static int sched_show(struct seq_file *m, void *v)
1396 {
1397 	struct inode *inode = m->private;
1398 	struct task_struct *p;
1399 
1400 	p = get_proc_task(inode);
1401 	if (!p)
1402 		return -ESRCH;
1403 	proc_sched_show_task(p, m);
1404 
1405 	put_task_struct(p);
1406 
1407 	return 0;
1408 }
1409 
1410 static ssize_t
1411 sched_write(struct file *file, const char __user *buf,
1412 	    size_t count, loff_t *offset)
1413 {
1414 	struct inode *inode = file_inode(file);
1415 	struct task_struct *p;
1416 
1417 	p = get_proc_task(inode);
1418 	if (!p)
1419 		return -ESRCH;
1420 	proc_sched_set_task(p);
1421 
1422 	put_task_struct(p);
1423 
1424 	return count;
1425 }
1426 
1427 static int sched_open(struct inode *inode, struct file *filp)
1428 {
1429 	return single_open(filp, sched_show, inode);
1430 }
1431 
1432 static const struct file_operations proc_pid_sched_operations = {
1433 	.open		= sched_open,
1434 	.read		= seq_read,
1435 	.write		= sched_write,
1436 	.llseek		= seq_lseek,
1437 	.release	= single_release,
1438 };
1439 
1440 #endif
1441 
1442 #ifdef CONFIG_SCHED_AUTOGROUP
1443 /*
1444  * Print out autogroup related information:
1445  */
1446 static int sched_autogroup_show(struct seq_file *m, void *v)
1447 {
1448 	struct inode *inode = m->private;
1449 	struct task_struct *p;
1450 
1451 	p = get_proc_task(inode);
1452 	if (!p)
1453 		return -ESRCH;
1454 	proc_sched_autogroup_show_task(p, m);
1455 
1456 	put_task_struct(p);
1457 
1458 	return 0;
1459 }
1460 
1461 static ssize_t
1462 sched_autogroup_write(struct file *file, const char __user *buf,
1463 	    size_t count, loff_t *offset)
1464 {
1465 	struct inode *inode = file_inode(file);
1466 	struct task_struct *p;
1467 	char buffer[PROC_NUMBUF];
1468 	int nice;
1469 	int err;
1470 
1471 	memset(buffer, 0, sizeof(buffer));
1472 	if (count > sizeof(buffer) - 1)
1473 		count = sizeof(buffer) - 1;
1474 	if (copy_from_user(buffer, buf, count))
1475 		return -EFAULT;
1476 
1477 	err = kstrtoint(strstrip(buffer), 0, &nice);
1478 	if (err < 0)
1479 		return err;
1480 
1481 	p = get_proc_task(inode);
1482 	if (!p)
1483 		return -ESRCH;
1484 
1485 	err = proc_sched_autogroup_set_nice(p, nice);
1486 	if (err)
1487 		count = err;
1488 
1489 	put_task_struct(p);
1490 
1491 	return count;
1492 }
1493 
1494 static int sched_autogroup_open(struct inode *inode, struct file *filp)
1495 {
1496 	int ret;
1497 
1498 	ret = single_open(filp, sched_autogroup_show, NULL);
1499 	if (!ret) {
1500 		struct seq_file *m = filp->private_data;
1501 
1502 		m->private = inode;
1503 	}
1504 	return ret;
1505 }
1506 
1507 static const struct file_operations proc_pid_sched_autogroup_operations = {
1508 	.open		= sched_autogroup_open,
1509 	.read		= seq_read,
1510 	.write		= sched_autogroup_write,
1511 	.llseek		= seq_lseek,
1512 	.release	= single_release,
1513 };
1514 
1515 #endif /* CONFIG_SCHED_AUTOGROUP */
1516 
1517 static ssize_t comm_write(struct file *file, const char __user *buf,
1518 				size_t count, loff_t *offset)
1519 {
1520 	struct inode *inode = file_inode(file);
1521 	struct task_struct *p;
1522 	char buffer[TASK_COMM_LEN];
1523 	const size_t maxlen = sizeof(buffer) - 1;
1524 
1525 	memset(buffer, 0, sizeof(buffer));
1526 	if (copy_from_user(buffer, buf, count > maxlen ? maxlen : count))
1527 		return -EFAULT;
1528 
1529 	p = get_proc_task(inode);
1530 	if (!p)
1531 		return -ESRCH;
1532 
1533 	if (same_thread_group(current, p))
1534 		set_task_comm(p, buffer);
1535 	else
1536 		count = -EINVAL;
1537 
1538 	put_task_struct(p);
1539 
1540 	return count;
1541 }
1542 
1543 static int comm_show(struct seq_file *m, void *v)
1544 {
1545 	struct inode *inode = m->private;
1546 	struct task_struct *p;
1547 
1548 	p = get_proc_task(inode);
1549 	if (!p)
1550 		return -ESRCH;
1551 
1552 	task_lock(p);
1553 	seq_printf(m, "%s\n", p->comm);
1554 	task_unlock(p);
1555 
1556 	put_task_struct(p);
1557 
1558 	return 0;
1559 }
1560 
1561 static int comm_open(struct inode *inode, struct file *filp)
1562 {
1563 	return single_open(filp, comm_show, inode);
1564 }
1565 
1566 static const struct file_operations proc_pid_set_comm_operations = {
1567 	.open		= comm_open,
1568 	.read		= seq_read,
1569 	.write		= comm_write,
1570 	.llseek		= seq_lseek,
1571 	.release	= single_release,
1572 };
1573 
1574 static int proc_exe_link(struct dentry *dentry, struct path *exe_path)
1575 {
1576 	struct task_struct *task;
1577 	struct file *exe_file;
1578 
1579 	task = get_proc_task(d_inode(dentry));
1580 	if (!task)
1581 		return -ENOENT;
1582 	exe_file = get_task_exe_file(task);
1583 	put_task_struct(task);
1584 	if (exe_file) {
1585 		*exe_path = exe_file->f_path;
1586 		path_get(&exe_file->f_path);
1587 		fput(exe_file);
1588 		return 0;
1589 	} else
1590 		return -ENOENT;
1591 }
1592 
1593 static const char *proc_pid_get_link(struct dentry *dentry,
1594 				     struct inode *inode,
1595 				     struct delayed_call *done)
1596 {
1597 	struct path path;
1598 	int error = -EACCES;
1599 
1600 	if (!dentry)
1601 		return ERR_PTR(-ECHILD);
1602 
1603 	/* Are we allowed to snoop on the tasks file descriptors? */
1604 	if (!proc_fd_access_allowed(inode))
1605 		goto out;
1606 
1607 	error = PROC_I(inode)->op.proc_get_link(dentry, &path);
1608 	if (error)
1609 		goto out;
1610 
1611 	nd_jump_link(&path);
1612 	return NULL;
1613 out:
1614 	return ERR_PTR(error);
1615 }
1616 
1617 static int do_proc_readlink(struct path *path, char __user *buffer, int buflen)
1618 {
1619 	char *tmp = (char*)__get_free_page(GFP_TEMPORARY);
1620 	char *pathname;
1621 	int len;
1622 
1623 	if (!tmp)
1624 		return -ENOMEM;
1625 
1626 	pathname = d_path(path, tmp, PAGE_SIZE);
1627 	len = PTR_ERR(pathname);
1628 	if (IS_ERR(pathname))
1629 		goto out;
1630 	len = tmp + PAGE_SIZE - 1 - pathname;
1631 
1632 	if (len > buflen)
1633 		len = buflen;
1634 	if (copy_to_user(buffer, pathname, len))
1635 		len = -EFAULT;
1636  out:
1637 	free_page((unsigned long)tmp);
1638 	return len;
1639 }
1640 
1641 static int proc_pid_readlink(struct dentry * dentry, char __user * buffer, int buflen)
1642 {
1643 	int error = -EACCES;
1644 	struct inode *inode = d_inode(dentry);
1645 	struct path path;
1646 
1647 	/* Are we allowed to snoop on the tasks file descriptors? */
1648 	if (!proc_fd_access_allowed(inode))
1649 		goto out;
1650 
1651 	error = PROC_I(inode)->op.proc_get_link(dentry, &path);
1652 	if (error)
1653 		goto out;
1654 
1655 	error = do_proc_readlink(&path, buffer, buflen);
1656 	path_put(&path);
1657 out:
1658 	return error;
1659 }
1660 
1661 const struct inode_operations proc_pid_link_inode_operations = {
1662 	.readlink	= proc_pid_readlink,
1663 	.get_link	= proc_pid_get_link,
1664 	.setattr	= proc_setattr,
1665 };
1666 
1667 
1668 /* building an inode */
1669 
1670 struct inode *proc_pid_make_inode(struct super_block * sb,
1671 				  struct task_struct *task, umode_t mode)
1672 {
1673 	struct inode * inode;
1674 	struct proc_inode *ei;
1675 	const struct cred *cred;
1676 
1677 	/* We need a new inode */
1678 
1679 	inode = new_inode(sb);
1680 	if (!inode)
1681 		goto out;
1682 
1683 	/* Common stuff */
1684 	ei = PROC_I(inode);
1685 	inode->i_mode = mode;
1686 	inode->i_ino = get_next_ino();
1687 	inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
1688 	inode->i_op = &proc_def_inode_operations;
1689 
1690 	/*
1691 	 * grab the reference to task.
1692 	 */
1693 	ei->pid = get_task_pid(task, PIDTYPE_PID);
1694 	if (!ei->pid)
1695 		goto out_unlock;
1696 
1697 	if (task_dumpable(task)) {
1698 		rcu_read_lock();
1699 		cred = __task_cred(task);
1700 		inode->i_uid = cred->euid;
1701 		inode->i_gid = cred->egid;
1702 		rcu_read_unlock();
1703 	}
1704 	security_task_to_inode(task, inode);
1705 
1706 out:
1707 	return inode;
1708 
1709 out_unlock:
1710 	iput(inode);
1711 	return NULL;
1712 }
1713 
1714 int pid_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
1715 {
1716 	struct inode *inode = d_inode(dentry);
1717 	struct task_struct *task;
1718 	const struct cred *cred;
1719 	struct pid_namespace *pid = dentry->d_sb->s_fs_info;
1720 
1721 	generic_fillattr(inode, stat);
1722 
1723 	rcu_read_lock();
1724 	stat->uid = GLOBAL_ROOT_UID;
1725 	stat->gid = GLOBAL_ROOT_GID;
1726 	task = pid_task(proc_pid(inode), PIDTYPE_PID);
1727 	if (task) {
1728 		if (!has_pid_permissions(pid, task, 2)) {
1729 			rcu_read_unlock();
1730 			/*
1731 			 * This doesn't prevent learning whether PID exists,
1732 			 * it only makes getattr() consistent with readdir().
1733 			 */
1734 			return -ENOENT;
1735 		}
1736 		if ((inode->i_mode == (S_IFDIR|S_IRUGO|S_IXUGO)) ||
1737 		    task_dumpable(task)) {
1738 			cred = __task_cred(task);
1739 			stat->uid = cred->euid;
1740 			stat->gid = cred->egid;
1741 		}
1742 	}
1743 	rcu_read_unlock();
1744 	return 0;
1745 }
1746 
1747 /* dentry stuff */
1748 
1749 /*
1750  *	Exceptional case: normally we are not allowed to unhash a busy
1751  * directory. In this case, however, we can do it - no aliasing problems
1752  * due to the way we treat inodes.
1753  *
1754  * Rewrite the inode's ownerships here because the owning task may have
1755  * performed a setuid(), etc.
1756  *
1757  * Before the /proc/pid/status file was created the only way to read
1758  * the effective uid of a /process was to stat /proc/pid.  Reading
1759  * /proc/pid/status is slow enough that procps and other packages
1760  * kept stating /proc/pid.  To keep the rules in /proc simple I have
1761  * made this apply to all per process world readable and executable
1762  * directories.
1763  */
1764 int pid_revalidate(struct dentry *dentry, unsigned int flags)
1765 {
1766 	struct inode *inode;
1767 	struct task_struct *task;
1768 	const struct cred *cred;
1769 
1770 	if (flags & LOOKUP_RCU)
1771 		return -ECHILD;
1772 
1773 	inode = d_inode(dentry);
1774 	task = get_proc_task(inode);
1775 
1776 	if (task) {
1777 		if ((inode->i_mode == (S_IFDIR|S_IRUGO|S_IXUGO)) ||
1778 		    task_dumpable(task)) {
1779 			rcu_read_lock();
1780 			cred = __task_cred(task);
1781 			inode->i_uid = cred->euid;
1782 			inode->i_gid = cred->egid;
1783 			rcu_read_unlock();
1784 		} else {
1785 			inode->i_uid = GLOBAL_ROOT_UID;
1786 			inode->i_gid = GLOBAL_ROOT_GID;
1787 		}
1788 		inode->i_mode &= ~(S_ISUID | S_ISGID);
1789 		security_task_to_inode(task, inode);
1790 		put_task_struct(task);
1791 		return 1;
1792 	}
1793 	return 0;
1794 }
1795 
1796 static inline bool proc_inode_is_dead(struct inode *inode)
1797 {
1798 	return !proc_pid(inode)->tasks[PIDTYPE_PID].first;
1799 }
1800 
1801 int pid_delete_dentry(const struct dentry *dentry)
1802 {
1803 	/* Is the task we represent dead?
1804 	 * If so, then don't put the dentry on the lru list,
1805 	 * kill it immediately.
1806 	 */
1807 	return proc_inode_is_dead(d_inode(dentry));
1808 }
1809 
1810 const struct dentry_operations pid_dentry_operations =
1811 {
1812 	.d_revalidate	= pid_revalidate,
1813 	.d_delete	= pid_delete_dentry,
1814 };
1815 
1816 /* Lookups */
1817 
1818 /*
1819  * Fill a directory entry.
1820  *
1821  * If possible create the dcache entry and derive our inode number and
1822  * file type from dcache entry.
1823  *
1824  * Since all of the proc inode numbers are dynamically generated, the inode
1825  * numbers do not exist until the inode is cache.  This means creating the
1826  * the dcache entry in readdir is necessary to keep the inode numbers
1827  * reported by readdir in sync with the inode numbers reported
1828  * by stat.
1829  */
1830 bool proc_fill_cache(struct file *file, struct dir_context *ctx,
1831 	const char *name, int len,
1832 	instantiate_t instantiate, struct task_struct *task, const void *ptr)
1833 {
1834 	struct dentry *child, *dir = file->f_path.dentry;
1835 	struct qstr qname = QSTR_INIT(name, len);
1836 	struct inode *inode;
1837 	unsigned type;
1838 	ino_t ino;
1839 
1840 	child = d_hash_and_lookup(dir, &qname);
1841 	if (!child) {
1842 		DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
1843 		child = d_alloc_parallel(dir, &qname, &wq);
1844 		if (IS_ERR(child))
1845 			goto end_instantiate;
1846 		if (d_in_lookup(child)) {
1847 			int err = instantiate(d_inode(dir), child, task, ptr);
1848 			d_lookup_done(child);
1849 			if (err < 0) {
1850 				dput(child);
1851 				goto end_instantiate;
1852 			}
1853 		}
1854 	}
1855 	inode = d_inode(child);
1856 	ino = inode->i_ino;
1857 	type = inode->i_mode >> 12;
1858 	dput(child);
1859 	return dir_emit(ctx, name, len, ino, type);
1860 
1861 end_instantiate:
1862 	return dir_emit(ctx, name, len, 1, DT_UNKNOWN);
1863 }
1864 
1865 /*
1866  * dname_to_vma_addr - maps a dentry name into two unsigned longs
1867  * which represent vma start and end addresses.
1868  */
1869 static int dname_to_vma_addr(struct dentry *dentry,
1870 			     unsigned long *start, unsigned long *end)
1871 {
1872 	if (sscanf(dentry->d_name.name, "%lx-%lx", start, end) != 2)
1873 		return -EINVAL;
1874 
1875 	return 0;
1876 }
1877 
1878 static int map_files_d_revalidate(struct dentry *dentry, unsigned int flags)
1879 {
1880 	unsigned long vm_start, vm_end;
1881 	bool exact_vma_exists = false;
1882 	struct mm_struct *mm = NULL;
1883 	struct task_struct *task;
1884 	const struct cred *cred;
1885 	struct inode *inode;
1886 	int status = 0;
1887 
1888 	if (flags & LOOKUP_RCU)
1889 		return -ECHILD;
1890 
1891 	inode = d_inode(dentry);
1892 	task = get_proc_task(inode);
1893 	if (!task)
1894 		goto out_notask;
1895 
1896 	mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
1897 	if (IS_ERR_OR_NULL(mm))
1898 		goto out;
1899 
1900 	if (!dname_to_vma_addr(dentry, &vm_start, &vm_end)) {
1901 		down_read(&mm->mmap_sem);
1902 		exact_vma_exists = !!find_exact_vma(mm, vm_start, vm_end);
1903 		up_read(&mm->mmap_sem);
1904 	}
1905 
1906 	mmput(mm);
1907 
1908 	if (exact_vma_exists) {
1909 		if (task_dumpable(task)) {
1910 			rcu_read_lock();
1911 			cred = __task_cred(task);
1912 			inode->i_uid = cred->euid;
1913 			inode->i_gid = cred->egid;
1914 			rcu_read_unlock();
1915 		} else {
1916 			inode->i_uid = GLOBAL_ROOT_UID;
1917 			inode->i_gid = GLOBAL_ROOT_GID;
1918 		}
1919 		security_task_to_inode(task, inode);
1920 		status = 1;
1921 	}
1922 
1923 out:
1924 	put_task_struct(task);
1925 
1926 out_notask:
1927 	return status;
1928 }
1929 
1930 static const struct dentry_operations tid_map_files_dentry_operations = {
1931 	.d_revalidate	= map_files_d_revalidate,
1932 	.d_delete	= pid_delete_dentry,
1933 };
1934 
1935 static int map_files_get_link(struct dentry *dentry, struct path *path)
1936 {
1937 	unsigned long vm_start, vm_end;
1938 	struct vm_area_struct *vma;
1939 	struct task_struct *task;
1940 	struct mm_struct *mm;
1941 	int rc;
1942 
1943 	rc = -ENOENT;
1944 	task = get_proc_task(d_inode(dentry));
1945 	if (!task)
1946 		goto out;
1947 
1948 	mm = get_task_mm(task);
1949 	put_task_struct(task);
1950 	if (!mm)
1951 		goto out;
1952 
1953 	rc = dname_to_vma_addr(dentry, &vm_start, &vm_end);
1954 	if (rc)
1955 		goto out_mmput;
1956 
1957 	rc = -ENOENT;
1958 	down_read(&mm->mmap_sem);
1959 	vma = find_exact_vma(mm, vm_start, vm_end);
1960 	if (vma && vma->vm_file) {
1961 		*path = vma->vm_file->f_path;
1962 		path_get(path);
1963 		rc = 0;
1964 	}
1965 	up_read(&mm->mmap_sem);
1966 
1967 out_mmput:
1968 	mmput(mm);
1969 out:
1970 	return rc;
1971 }
1972 
1973 struct map_files_info {
1974 	fmode_t		mode;
1975 	unsigned int	len;
1976 	unsigned char	name[4*sizeof(long)+2]; /* max: %lx-%lx\0 */
1977 };
1978 
1979 /*
1980  * Only allow CAP_SYS_ADMIN to follow the links, due to concerns about how the
1981  * symlinks may be used to bypass permissions on ancestor directories in the
1982  * path to the file in question.
1983  */
1984 static const char *
1985 proc_map_files_get_link(struct dentry *dentry,
1986 			struct inode *inode,
1987 		        struct delayed_call *done)
1988 {
1989 	if (!capable(CAP_SYS_ADMIN))
1990 		return ERR_PTR(-EPERM);
1991 
1992 	return proc_pid_get_link(dentry, inode, done);
1993 }
1994 
1995 /*
1996  * Identical to proc_pid_link_inode_operations except for get_link()
1997  */
1998 static const struct inode_operations proc_map_files_link_inode_operations = {
1999 	.readlink	= proc_pid_readlink,
2000 	.get_link	= proc_map_files_get_link,
2001 	.setattr	= proc_setattr,
2002 };
2003 
2004 static int
2005 proc_map_files_instantiate(struct inode *dir, struct dentry *dentry,
2006 			   struct task_struct *task, const void *ptr)
2007 {
2008 	fmode_t mode = (fmode_t)(unsigned long)ptr;
2009 	struct proc_inode *ei;
2010 	struct inode *inode;
2011 
2012 	inode = proc_pid_make_inode(dir->i_sb, task, S_IFLNK |
2013 				    ((mode & FMODE_READ ) ? S_IRUSR : 0) |
2014 				    ((mode & FMODE_WRITE) ? S_IWUSR : 0));
2015 	if (!inode)
2016 		return -ENOENT;
2017 
2018 	ei = PROC_I(inode);
2019 	ei->op.proc_get_link = map_files_get_link;
2020 
2021 	inode->i_op = &proc_map_files_link_inode_operations;
2022 	inode->i_size = 64;
2023 
2024 	d_set_d_op(dentry, &tid_map_files_dentry_operations);
2025 	d_add(dentry, inode);
2026 
2027 	return 0;
2028 }
2029 
2030 static struct dentry *proc_map_files_lookup(struct inode *dir,
2031 		struct dentry *dentry, unsigned int flags)
2032 {
2033 	unsigned long vm_start, vm_end;
2034 	struct vm_area_struct *vma;
2035 	struct task_struct *task;
2036 	int result;
2037 	struct mm_struct *mm;
2038 
2039 	result = -ENOENT;
2040 	task = get_proc_task(dir);
2041 	if (!task)
2042 		goto out;
2043 
2044 	result = -EACCES;
2045 	if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
2046 		goto out_put_task;
2047 
2048 	result = -ENOENT;
2049 	if (dname_to_vma_addr(dentry, &vm_start, &vm_end))
2050 		goto out_put_task;
2051 
2052 	mm = get_task_mm(task);
2053 	if (!mm)
2054 		goto out_put_task;
2055 
2056 	down_read(&mm->mmap_sem);
2057 	vma = find_exact_vma(mm, vm_start, vm_end);
2058 	if (!vma)
2059 		goto out_no_vma;
2060 
2061 	if (vma->vm_file)
2062 		result = proc_map_files_instantiate(dir, dentry, task,
2063 				(void *)(unsigned long)vma->vm_file->f_mode);
2064 
2065 out_no_vma:
2066 	up_read(&mm->mmap_sem);
2067 	mmput(mm);
2068 out_put_task:
2069 	put_task_struct(task);
2070 out:
2071 	return ERR_PTR(result);
2072 }
2073 
2074 static const struct inode_operations proc_map_files_inode_operations = {
2075 	.lookup		= proc_map_files_lookup,
2076 	.permission	= proc_fd_permission,
2077 	.setattr	= proc_setattr,
2078 };
2079 
2080 static int
2081 proc_map_files_readdir(struct file *file, struct dir_context *ctx)
2082 {
2083 	struct vm_area_struct *vma;
2084 	struct task_struct *task;
2085 	struct mm_struct *mm;
2086 	unsigned long nr_files, pos, i;
2087 	struct flex_array *fa = NULL;
2088 	struct map_files_info info;
2089 	struct map_files_info *p;
2090 	int ret;
2091 
2092 	ret = -ENOENT;
2093 	task = get_proc_task(file_inode(file));
2094 	if (!task)
2095 		goto out;
2096 
2097 	ret = -EACCES;
2098 	if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
2099 		goto out_put_task;
2100 
2101 	ret = 0;
2102 	if (!dir_emit_dots(file, ctx))
2103 		goto out_put_task;
2104 
2105 	mm = get_task_mm(task);
2106 	if (!mm)
2107 		goto out_put_task;
2108 	down_read(&mm->mmap_sem);
2109 
2110 	nr_files = 0;
2111 
2112 	/*
2113 	 * We need two passes here:
2114 	 *
2115 	 *  1) Collect vmas of mapped files with mmap_sem taken
2116 	 *  2) Release mmap_sem and instantiate entries
2117 	 *
2118 	 * otherwise we get lockdep complained, since filldir()
2119 	 * routine might require mmap_sem taken in might_fault().
2120 	 */
2121 
2122 	for (vma = mm->mmap, pos = 2; vma; vma = vma->vm_next) {
2123 		if (vma->vm_file && ++pos > ctx->pos)
2124 			nr_files++;
2125 	}
2126 
2127 	if (nr_files) {
2128 		fa = flex_array_alloc(sizeof(info), nr_files,
2129 					GFP_KERNEL);
2130 		if (!fa || flex_array_prealloc(fa, 0, nr_files,
2131 						GFP_KERNEL)) {
2132 			ret = -ENOMEM;
2133 			if (fa)
2134 				flex_array_free(fa);
2135 			up_read(&mm->mmap_sem);
2136 			mmput(mm);
2137 			goto out_put_task;
2138 		}
2139 		for (i = 0, vma = mm->mmap, pos = 2; vma;
2140 				vma = vma->vm_next) {
2141 			if (!vma->vm_file)
2142 				continue;
2143 			if (++pos <= ctx->pos)
2144 				continue;
2145 
2146 			info.mode = vma->vm_file->f_mode;
2147 			info.len = snprintf(info.name,
2148 					sizeof(info.name), "%lx-%lx",
2149 					vma->vm_start, vma->vm_end);
2150 			if (flex_array_put(fa, i++, &info, GFP_KERNEL))
2151 				BUG();
2152 		}
2153 	}
2154 	up_read(&mm->mmap_sem);
2155 
2156 	for (i = 0; i < nr_files; i++) {
2157 		p = flex_array_get(fa, i);
2158 		if (!proc_fill_cache(file, ctx,
2159 				      p->name, p->len,
2160 				      proc_map_files_instantiate,
2161 				      task,
2162 				      (void *)(unsigned long)p->mode))
2163 			break;
2164 		ctx->pos++;
2165 	}
2166 	if (fa)
2167 		flex_array_free(fa);
2168 	mmput(mm);
2169 
2170 out_put_task:
2171 	put_task_struct(task);
2172 out:
2173 	return ret;
2174 }
2175 
2176 static const struct file_operations proc_map_files_operations = {
2177 	.read		= generic_read_dir,
2178 	.iterate_shared	= proc_map_files_readdir,
2179 	.llseek		= generic_file_llseek,
2180 };
2181 
2182 #ifdef CONFIG_CHECKPOINT_RESTORE
2183 struct timers_private {
2184 	struct pid *pid;
2185 	struct task_struct *task;
2186 	struct sighand_struct *sighand;
2187 	struct pid_namespace *ns;
2188 	unsigned long flags;
2189 };
2190 
2191 static void *timers_start(struct seq_file *m, loff_t *pos)
2192 {
2193 	struct timers_private *tp = m->private;
2194 
2195 	tp->task = get_pid_task(tp->pid, PIDTYPE_PID);
2196 	if (!tp->task)
2197 		return ERR_PTR(-ESRCH);
2198 
2199 	tp->sighand = lock_task_sighand(tp->task, &tp->flags);
2200 	if (!tp->sighand)
2201 		return ERR_PTR(-ESRCH);
2202 
2203 	return seq_list_start(&tp->task->signal->posix_timers, *pos);
2204 }
2205 
2206 static void *timers_next(struct seq_file *m, void *v, loff_t *pos)
2207 {
2208 	struct timers_private *tp = m->private;
2209 	return seq_list_next(v, &tp->task->signal->posix_timers, pos);
2210 }
2211 
2212 static void timers_stop(struct seq_file *m, void *v)
2213 {
2214 	struct timers_private *tp = m->private;
2215 
2216 	if (tp->sighand) {
2217 		unlock_task_sighand(tp->task, &tp->flags);
2218 		tp->sighand = NULL;
2219 	}
2220 
2221 	if (tp->task) {
2222 		put_task_struct(tp->task);
2223 		tp->task = NULL;
2224 	}
2225 }
2226 
2227 static int show_timer(struct seq_file *m, void *v)
2228 {
2229 	struct k_itimer *timer;
2230 	struct timers_private *tp = m->private;
2231 	int notify;
2232 	static const char * const nstr[] = {
2233 		[SIGEV_SIGNAL] = "signal",
2234 		[SIGEV_NONE] = "none",
2235 		[SIGEV_THREAD] = "thread",
2236 	};
2237 
2238 	timer = list_entry((struct list_head *)v, struct k_itimer, list);
2239 	notify = timer->it_sigev_notify;
2240 
2241 	seq_printf(m, "ID: %d\n", timer->it_id);
2242 	seq_printf(m, "signal: %d/%p\n",
2243 		   timer->sigq->info.si_signo,
2244 		   timer->sigq->info.si_value.sival_ptr);
2245 	seq_printf(m, "notify: %s/%s.%d\n",
2246 		   nstr[notify & ~SIGEV_THREAD_ID],
2247 		   (notify & SIGEV_THREAD_ID) ? "tid" : "pid",
2248 		   pid_nr_ns(timer->it_pid, tp->ns));
2249 	seq_printf(m, "ClockID: %d\n", timer->it_clock);
2250 
2251 	return 0;
2252 }
2253 
2254 static const struct seq_operations proc_timers_seq_ops = {
2255 	.start	= timers_start,
2256 	.next	= timers_next,
2257 	.stop	= timers_stop,
2258 	.show	= show_timer,
2259 };
2260 
2261 static int proc_timers_open(struct inode *inode, struct file *file)
2262 {
2263 	struct timers_private *tp;
2264 
2265 	tp = __seq_open_private(file, &proc_timers_seq_ops,
2266 			sizeof(struct timers_private));
2267 	if (!tp)
2268 		return -ENOMEM;
2269 
2270 	tp->pid = proc_pid(inode);
2271 	tp->ns = inode->i_sb->s_fs_info;
2272 	return 0;
2273 }
2274 
2275 static const struct file_operations proc_timers_operations = {
2276 	.open		= proc_timers_open,
2277 	.read		= seq_read,
2278 	.llseek		= seq_lseek,
2279 	.release	= seq_release_private,
2280 };
2281 #endif
2282 
2283 static ssize_t timerslack_ns_write(struct file *file, const char __user *buf,
2284 					size_t count, loff_t *offset)
2285 {
2286 	struct inode *inode = file_inode(file);
2287 	struct task_struct *p;
2288 	u64 slack_ns;
2289 	int err;
2290 
2291 	err = kstrtoull_from_user(buf, count, 10, &slack_ns);
2292 	if (err < 0)
2293 		return err;
2294 
2295 	p = get_proc_task(inode);
2296 	if (!p)
2297 		return -ESRCH;
2298 
2299 	if (p != current) {
2300 		if (!capable(CAP_SYS_NICE)) {
2301 			count = -EPERM;
2302 			goto out;
2303 		}
2304 
2305 		err = security_task_setscheduler(p);
2306 		if (err) {
2307 			count = err;
2308 			goto out;
2309 		}
2310 	}
2311 
2312 	task_lock(p);
2313 	if (slack_ns == 0)
2314 		p->timer_slack_ns = p->default_timer_slack_ns;
2315 	else
2316 		p->timer_slack_ns = slack_ns;
2317 	task_unlock(p);
2318 
2319 out:
2320 	put_task_struct(p);
2321 
2322 	return count;
2323 }
2324 
2325 static int timerslack_ns_show(struct seq_file *m, void *v)
2326 {
2327 	struct inode *inode = m->private;
2328 	struct task_struct *p;
2329 	int err = 0;
2330 
2331 	p = get_proc_task(inode);
2332 	if (!p)
2333 		return -ESRCH;
2334 
2335 	if (p != current) {
2336 
2337 		if (!capable(CAP_SYS_NICE)) {
2338 			err = -EPERM;
2339 			goto out;
2340 		}
2341 		err = security_task_getscheduler(p);
2342 		if (err)
2343 			goto out;
2344 	}
2345 
2346 	task_lock(p);
2347 	seq_printf(m, "%llu\n", p->timer_slack_ns);
2348 	task_unlock(p);
2349 
2350 out:
2351 	put_task_struct(p);
2352 
2353 	return err;
2354 }
2355 
2356 static int timerslack_ns_open(struct inode *inode, struct file *filp)
2357 {
2358 	return single_open(filp, timerslack_ns_show, inode);
2359 }
2360 
2361 static const struct file_operations proc_pid_set_timerslack_ns_operations = {
2362 	.open		= timerslack_ns_open,
2363 	.read		= seq_read,
2364 	.write		= timerslack_ns_write,
2365 	.llseek		= seq_lseek,
2366 	.release	= single_release,
2367 };
2368 
2369 static int proc_pident_instantiate(struct inode *dir,
2370 	struct dentry *dentry, struct task_struct *task, const void *ptr)
2371 {
2372 	const struct pid_entry *p = ptr;
2373 	struct inode *inode;
2374 	struct proc_inode *ei;
2375 
2376 	inode = proc_pid_make_inode(dir->i_sb, task, p->mode);
2377 	if (!inode)
2378 		goto out;
2379 
2380 	ei = PROC_I(inode);
2381 	if (S_ISDIR(inode->i_mode))
2382 		set_nlink(inode, 2);	/* Use getattr to fix if necessary */
2383 	if (p->iop)
2384 		inode->i_op = p->iop;
2385 	if (p->fop)
2386 		inode->i_fop = p->fop;
2387 	ei->op = p->op;
2388 	d_set_d_op(dentry, &pid_dentry_operations);
2389 	d_add(dentry, inode);
2390 	/* Close the race of the process dying before we return the dentry */
2391 	if (pid_revalidate(dentry, 0))
2392 		return 0;
2393 out:
2394 	return -ENOENT;
2395 }
2396 
2397 static struct dentry *proc_pident_lookup(struct inode *dir,
2398 					 struct dentry *dentry,
2399 					 const struct pid_entry *ents,
2400 					 unsigned int nents)
2401 {
2402 	int error;
2403 	struct task_struct *task = get_proc_task(dir);
2404 	const struct pid_entry *p, *last;
2405 
2406 	error = -ENOENT;
2407 
2408 	if (!task)
2409 		goto out_no_task;
2410 
2411 	/*
2412 	 * Yes, it does not scale. And it should not. Don't add
2413 	 * new entries into /proc/<tgid>/ without very good reasons.
2414 	 */
2415 	last = &ents[nents];
2416 	for (p = ents; p < last; p++) {
2417 		if (p->len != dentry->d_name.len)
2418 			continue;
2419 		if (!memcmp(dentry->d_name.name, p->name, p->len))
2420 			break;
2421 	}
2422 	if (p >= last)
2423 		goto out;
2424 
2425 	error = proc_pident_instantiate(dir, dentry, task, p);
2426 out:
2427 	put_task_struct(task);
2428 out_no_task:
2429 	return ERR_PTR(error);
2430 }
2431 
2432 static int proc_pident_readdir(struct file *file, struct dir_context *ctx,
2433 		const struct pid_entry *ents, unsigned int nents)
2434 {
2435 	struct task_struct *task = get_proc_task(file_inode(file));
2436 	const struct pid_entry *p;
2437 
2438 	if (!task)
2439 		return -ENOENT;
2440 
2441 	if (!dir_emit_dots(file, ctx))
2442 		goto out;
2443 
2444 	if (ctx->pos >= nents + 2)
2445 		goto out;
2446 
2447 	for (p = ents + (ctx->pos - 2); p < ents + nents; p++) {
2448 		if (!proc_fill_cache(file, ctx, p->name, p->len,
2449 				proc_pident_instantiate, task, p))
2450 			break;
2451 		ctx->pos++;
2452 	}
2453 out:
2454 	put_task_struct(task);
2455 	return 0;
2456 }
2457 
2458 #ifdef CONFIG_SECURITY
2459 static ssize_t proc_pid_attr_read(struct file * file, char __user * buf,
2460 				  size_t count, loff_t *ppos)
2461 {
2462 	struct inode * inode = file_inode(file);
2463 	char *p = NULL;
2464 	ssize_t length;
2465 	struct task_struct *task = get_proc_task(inode);
2466 
2467 	if (!task)
2468 		return -ESRCH;
2469 
2470 	length = security_getprocattr(task,
2471 				      (char*)file->f_path.dentry->d_name.name,
2472 				      &p);
2473 	put_task_struct(task);
2474 	if (length > 0)
2475 		length = simple_read_from_buffer(buf, count, ppos, p, length);
2476 	kfree(p);
2477 	return length;
2478 }
2479 
2480 static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
2481 				   size_t count, loff_t *ppos)
2482 {
2483 	struct inode * inode = file_inode(file);
2484 	void *page;
2485 	ssize_t length;
2486 	struct task_struct *task = get_proc_task(inode);
2487 
2488 	length = -ESRCH;
2489 	if (!task)
2490 		goto out_no_task;
2491 	if (count > PAGE_SIZE)
2492 		count = PAGE_SIZE;
2493 
2494 	/* No partial writes. */
2495 	length = -EINVAL;
2496 	if (*ppos != 0)
2497 		goto out;
2498 
2499 	page = memdup_user(buf, count);
2500 	if (IS_ERR(page)) {
2501 		length = PTR_ERR(page);
2502 		goto out;
2503 	}
2504 
2505 	/* Guard against adverse ptrace interaction */
2506 	length = mutex_lock_interruptible(&task->signal->cred_guard_mutex);
2507 	if (length < 0)
2508 		goto out_free;
2509 
2510 	length = security_setprocattr(task,
2511 				      (char*)file->f_path.dentry->d_name.name,
2512 				      page, count);
2513 	mutex_unlock(&task->signal->cred_guard_mutex);
2514 out_free:
2515 	kfree(page);
2516 out:
2517 	put_task_struct(task);
2518 out_no_task:
2519 	return length;
2520 }
2521 
2522 static const struct file_operations proc_pid_attr_operations = {
2523 	.read		= proc_pid_attr_read,
2524 	.write		= proc_pid_attr_write,
2525 	.llseek		= generic_file_llseek,
2526 };
2527 
2528 static const struct pid_entry attr_dir_stuff[] = {
2529 	REG("current",    S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2530 	REG("prev",       S_IRUGO,	   proc_pid_attr_operations),
2531 	REG("exec",       S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2532 	REG("fscreate",   S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2533 	REG("keycreate",  S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2534 	REG("sockcreate", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2535 };
2536 
2537 static int proc_attr_dir_readdir(struct file *file, struct dir_context *ctx)
2538 {
2539 	return proc_pident_readdir(file, ctx,
2540 				   attr_dir_stuff, ARRAY_SIZE(attr_dir_stuff));
2541 }
2542 
2543 static const struct file_operations proc_attr_dir_operations = {
2544 	.read		= generic_read_dir,
2545 	.iterate_shared	= proc_attr_dir_readdir,
2546 	.llseek		= generic_file_llseek,
2547 };
2548 
2549 static struct dentry *proc_attr_dir_lookup(struct inode *dir,
2550 				struct dentry *dentry, unsigned int flags)
2551 {
2552 	return proc_pident_lookup(dir, dentry,
2553 				  attr_dir_stuff, ARRAY_SIZE(attr_dir_stuff));
2554 }
2555 
2556 static const struct inode_operations proc_attr_dir_inode_operations = {
2557 	.lookup		= proc_attr_dir_lookup,
2558 	.getattr	= pid_getattr,
2559 	.setattr	= proc_setattr,
2560 };
2561 
2562 #endif
2563 
2564 #ifdef CONFIG_ELF_CORE
2565 static ssize_t proc_coredump_filter_read(struct file *file, char __user *buf,
2566 					 size_t count, loff_t *ppos)
2567 {
2568 	struct task_struct *task = get_proc_task(file_inode(file));
2569 	struct mm_struct *mm;
2570 	char buffer[PROC_NUMBUF];
2571 	size_t len;
2572 	int ret;
2573 
2574 	if (!task)
2575 		return -ESRCH;
2576 
2577 	ret = 0;
2578 	mm = get_task_mm(task);
2579 	if (mm) {
2580 		len = snprintf(buffer, sizeof(buffer), "%08lx\n",
2581 			       ((mm->flags & MMF_DUMP_FILTER_MASK) >>
2582 				MMF_DUMP_FILTER_SHIFT));
2583 		mmput(mm);
2584 		ret = simple_read_from_buffer(buf, count, ppos, buffer, len);
2585 	}
2586 
2587 	put_task_struct(task);
2588 
2589 	return ret;
2590 }
2591 
2592 static ssize_t proc_coredump_filter_write(struct file *file,
2593 					  const char __user *buf,
2594 					  size_t count,
2595 					  loff_t *ppos)
2596 {
2597 	struct task_struct *task;
2598 	struct mm_struct *mm;
2599 	unsigned int val;
2600 	int ret;
2601 	int i;
2602 	unsigned long mask;
2603 
2604 	ret = kstrtouint_from_user(buf, count, 0, &val);
2605 	if (ret < 0)
2606 		return ret;
2607 
2608 	ret = -ESRCH;
2609 	task = get_proc_task(file_inode(file));
2610 	if (!task)
2611 		goto out_no_task;
2612 
2613 	mm = get_task_mm(task);
2614 	if (!mm)
2615 		goto out_no_mm;
2616 	ret = 0;
2617 
2618 	for (i = 0, mask = 1; i < MMF_DUMP_FILTER_BITS; i++, mask <<= 1) {
2619 		if (val & mask)
2620 			set_bit(i + MMF_DUMP_FILTER_SHIFT, &mm->flags);
2621 		else
2622 			clear_bit(i + MMF_DUMP_FILTER_SHIFT, &mm->flags);
2623 	}
2624 
2625 	mmput(mm);
2626  out_no_mm:
2627 	put_task_struct(task);
2628  out_no_task:
2629 	if (ret < 0)
2630 		return ret;
2631 	return count;
2632 }
2633 
2634 static const struct file_operations proc_coredump_filter_operations = {
2635 	.read		= proc_coredump_filter_read,
2636 	.write		= proc_coredump_filter_write,
2637 	.llseek		= generic_file_llseek,
2638 };
2639 #endif
2640 
2641 #ifdef CONFIG_TASK_IO_ACCOUNTING
2642 static int do_io_accounting(struct task_struct *task, struct seq_file *m, int whole)
2643 {
2644 	struct task_io_accounting acct = task->ioac;
2645 	unsigned long flags;
2646 	int result;
2647 
2648 	result = mutex_lock_killable(&task->signal->cred_guard_mutex);
2649 	if (result)
2650 		return result;
2651 
2652 	if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) {
2653 		result = -EACCES;
2654 		goto out_unlock;
2655 	}
2656 
2657 	if (whole && lock_task_sighand(task, &flags)) {
2658 		struct task_struct *t = task;
2659 
2660 		task_io_accounting_add(&acct, &task->signal->ioac);
2661 		while_each_thread(task, t)
2662 			task_io_accounting_add(&acct, &t->ioac);
2663 
2664 		unlock_task_sighand(task, &flags);
2665 	}
2666 	seq_printf(m,
2667 		   "rchar: %llu\n"
2668 		   "wchar: %llu\n"
2669 		   "syscr: %llu\n"
2670 		   "syscw: %llu\n"
2671 		   "read_bytes: %llu\n"
2672 		   "write_bytes: %llu\n"
2673 		   "cancelled_write_bytes: %llu\n",
2674 		   (unsigned long long)acct.rchar,
2675 		   (unsigned long long)acct.wchar,
2676 		   (unsigned long long)acct.syscr,
2677 		   (unsigned long long)acct.syscw,
2678 		   (unsigned long long)acct.read_bytes,
2679 		   (unsigned long long)acct.write_bytes,
2680 		   (unsigned long long)acct.cancelled_write_bytes);
2681 	result = 0;
2682 
2683 out_unlock:
2684 	mutex_unlock(&task->signal->cred_guard_mutex);
2685 	return result;
2686 }
2687 
2688 static int proc_tid_io_accounting(struct seq_file *m, struct pid_namespace *ns,
2689 				  struct pid *pid, struct task_struct *task)
2690 {
2691 	return do_io_accounting(task, m, 0);
2692 }
2693 
2694 static int proc_tgid_io_accounting(struct seq_file *m, struct pid_namespace *ns,
2695 				   struct pid *pid, struct task_struct *task)
2696 {
2697 	return do_io_accounting(task, m, 1);
2698 }
2699 #endif /* CONFIG_TASK_IO_ACCOUNTING */
2700 
2701 #ifdef CONFIG_USER_NS
2702 static int proc_id_map_open(struct inode *inode, struct file *file,
2703 	const struct seq_operations *seq_ops)
2704 {
2705 	struct user_namespace *ns = NULL;
2706 	struct task_struct *task;
2707 	struct seq_file *seq;
2708 	int ret = -EINVAL;
2709 
2710 	task = get_proc_task(inode);
2711 	if (task) {
2712 		rcu_read_lock();
2713 		ns = get_user_ns(task_cred_xxx(task, user_ns));
2714 		rcu_read_unlock();
2715 		put_task_struct(task);
2716 	}
2717 	if (!ns)
2718 		goto err;
2719 
2720 	ret = seq_open(file, seq_ops);
2721 	if (ret)
2722 		goto err_put_ns;
2723 
2724 	seq = file->private_data;
2725 	seq->private = ns;
2726 
2727 	return 0;
2728 err_put_ns:
2729 	put_user_ns(ns);
2730 err:
2731 	return ret;
2732 }
2733 
2734 static int proc_id_map_release(struct inode *inode, struct file *file)
2735 {
2736 	struct seq_file *seq = file->private_data;
2737 	struct user_namespace *ns = seq->private;
2738 	put_user_ns(ns);
2739 	return seq_release(inode, file);
2740 }
2741 
2742 static int proc_uid_map_open(struct inode *inode, struct file *file)
2743 {
2744 	return proc_id_map_open(inode, file, &proc_uid_seq_operations);
2745 }
2746 
2747 static int proc_gid_map_open(struct inode *inode, struct file *file)
2748 {
2749 	return proc_id_map_open(inode, file, &proc_gid_seq_operations);
2750 }
2751 
2752 static int proc_projid_map_open(struct inode *inode, struct file *file)
2753 {
2754 	return proc_id_map_open(inode, file, &proc_projid_seq_operations);
2755 }
2756 
2757 static const struct file_operations proc_uid_map_operations = {
2758 	.open		= proc_uid_map_open,
2759 	.write		= proc_uid_map_write,
2760 	.read		= seq_read,
2761 	.llseek		= seq_lseek,
2762 	.release	= proc_id_map_release,
2763 };
2764 
2765 static const struct file_operations proc_gid_map_operations = {
2766 	.open		= proc_gid_map_open,
2767 	.write		= proc_gid_map_write,
2768 	.read		= seq_read,
2769 	.llseek		= seq_lseek,
2770 	.release	= proc_id_map_release,
2771 };
2772 
2773 static const struct file_operations proc_projid_map_operations = {
2774 	.open		= proc_projid_map_open,
2775 	.write		= proc_projid_map_write,
2776 	.read		= seq_read,
2777 	.llseek		= seq_lseek,
2778 	.release	= proc_id_map_release,
2779 };
2780 
2781 static int proc_setgroups_open(struct inode *inode, struct file *file)
2782 {
2783 	struct user_namespace *ns = NULL;
2784 	struct task_struct *task;
2785 	int ret;
2786 
2787 	ret = -ESRCH;
2788 	task = get_proc_task(inode);
2789 	if (task) {
2790 		rcu_read_lock();
2791 		ns = get_user_ns(task_cred_xxx(task, user_ns));
2792 		rcu_read_unlock();
2793 		put_task_struct(task);
2794 	}
2795 	if (!ns)
2796 		goto err;
2797 
2798 	if (file->f_mode & FMODE_WRITE) {
2799 		ret = -EACCES;
2800 		if (!ns_capable(ns, CAP_SYS_ADMIN))
2801 			goto err_put_ns;
2802 	}
2803 
2804 	ret = single_open(file, &proc_setgroups_show, ns);
2805 	if (ret)
2806 		goto err_put_ns;
2807 
2808 	return 0;
2809 err_put_ns:
2810 	put_user_ns(ns);
2811 err:
2812 	return ret;
2813 }
2814 
2815 static int proc_setgroups_release(struct inode *inode, struct file *file)
2816 {
2817 	struct seq_file *seq = file->private_data;
2818 	struct user_namespace *ns = seq->private;
2819 	int ret = single_release(inode, file);
2820 	put_user_ns(ns);
2821 	return ret;
2822 }
2823 
2824 static const struct file_operations proc_setgroups_operations = {
2825 	.open		= proc_setgroups_open,
2826 	.write		= proc_setgroups_write,
2827 	.read		= seq_read,
2828 	.llseek		= seq_lseek,
2829 	.release	= proc_setgroups_release,
2830 };
2831 #endif /* CONFIG_USER_NS */
2832 
2833 static int proc_pid_personality(struct seq_file *m, struct pid_namespace *ns,
2834 				struct pid *pid, struct task_struct *task)
2835 {
2836 	int err = lock_trace(task);
2837 	if (!err) {
2838 		seq_printf(m, "%08x\n", task->personality);
2839 		unlock_trace(task);
2840 	}
2841 	return err;
2842 }
2843 
2844 /*
2845  * Thread groups
2846  */
2847 static const struct file_operations proc_task_operations;
2848 static const struct inode_operations proc_task_inode_operations;
2849 
2850 static const struct pid_entry tgid_base_stuff[] = {
2851 	DIR("task",       S_IRUGO|S_IXUGO, proc_task_inode_operations, proc_task_operations),
2852 	DIR("fd",         S_IRUSR|S_IXUSR, proc_fd_inode_operations, proc_fd_operations),
2853 	DIR("map_files",  S_IRUSR|S_IXUSR, proc_map_files_inode_operations, proc_map_files_operations),
2854 	DIR("fdinfo",     S_IRUSR|S_IXUSR, proc_fdinfo_inode_operations, proc_fdinfo_operations),
2855 	DIR("ns",	  S_IRUSR|S_IXUGO, proc_ns_dir_inode_operations, proc_ns_dir_operations),
2856 #ifdef CONFIG_NET
2857 	DIR("net",        S_IRUGO|S_IXUGO, proc_net_inode_operations, proc_net_operations),
2858 #endif
2859 	REG("environ",    S_IRUSR, proc_environ_operations),
2860 	REG("auxv",       S_IRUSR, proc_auxv_operations),
2861 	ONE("status",     S_IRUGO, proc_pid_status),
2862 	ONE("personality", S_IRUSR, proc_pid_personality),
2863 	ONE("limits",	  S_IRUGO, proc_pid_limits),
2864 #ifdef CONFIG_SCHED_DEBUG
2865 	REG("sched",      S_IRUGO|S_IWUSR, proc_pid_sched_operations),
2866 #endif
2867 #ifdef CONFIG_SCHED_AUTOGROUP
2868 	REG("autogroup",  S_IRUGO|S_IWUSR, proc_pid_sched_autogroup_operations),
2869 #endif
2870 	REG("comm",      S_IRUGO|S_IWUSR, proc_pid_set_comm_operations),
2871 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
2872 	ONE("syscall",    S_IRUSR, proc_pid_syscall),
2873 #endif
2874 	REG("cmdline",    S_IRUGO, proc_pid_cmdline_ops),
2875 	ONE("stat",       S_IRUGO, proc_tgid_stat),
2876 	ONE("statm",      S_IRUGO, proc_pid_statm),
2877 	REG("maps",       S_IRUGO, proc_pid_maps_operations),
2878 #ifdef CONFIG_NUMA
2879 	REG("numa_maps",  S_IRUGO, proc_pid_numa_maps_operations),
2880 #endif
2881 	REG("mem",        S_IRUSR|S_IWUSR, proc_mem_operations),
2882 	LNK("cwd",        proc_cwd_link),
2883 	LNK("root",       proc_root_link),
2884 	LNK("exe",        proc_exe_link),
2885 	REG("mounts",     S_IRUGO, proc_mounts_operations),
2886 	REG("mountinfo",  S_IRUGO, proc_mountinfo_operations),
2887 	REG("mountstats", S_IRUSR, proc_mountstats_operations),
2888 #ifdef CONFIG_PROC_PAGE_MONITOR
2889 	REG("clear_refs", S_IWUSR, proc_clear_refs_operations),
2890 	REG("smaps",      S_IRUGO, proc_pid_smaps_operations),
2891 	REG("pagemap",    S_IRUSR, proc_pagemap_operations),
2892 #endif
2893 #ifdef CONFIG_SECURITY
2894 	DIR("attr",       S_IRUGO|S_IXUGO, proc_attr_dir_inode_operations, proc_attr_dir_operations),
2895 #endif
2896 #ifdef CONFIG_KALLSYMS
2897 	ONE("wchan",      S_IRUGO, proc_pid_wchan),
2898 #endif
2899 #ifdef CONFIG_STACKTRACE
2900 	ONE("stack",      S_IRUSR, proc_pid_stack),
2901 #endif
2902 #ifdef CONFIG_SCHED_INFO
2903 	ONE("schedstat",  S_IRUGO, proc_pid_schedstat),
2904 #endif
2905 #ifdef CONFIG_LATENCYTOP
2906 	REG("latency",  S_IRUGO, proc_lstats_operations),
2907 #endif
2908 #ifdef CONFIG_PROC_PID_CPUSET
2909 	ONE("cpuset",     S_IRUGO, proc_cpuset_show),
2910 #endif
2911 #ifdef CONFIG_CGROUPS
2912 	ONE("cgroup",  S_IRUGO, proc_cgroup_show),
2913 #endif
2914 	ONE("oom_score",  S_IRUGO, proc_oom_score),
2915 	REG("oom_adj",    S_IRUGO|S_IWUSR, proc_oom_adj_operations),
2916 	REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
2917 #ifdef CONFIG_AUDITSYSCALL
2918 	REG("loginuid",   S_IWUSR|S_IRUGO, proc_loginuid_operations),
2919 	REG("sessionid",  S_IRUGO, proc_sessionid_operations),
2920 #endif
2921 #ifdef CONFIG_FAULT_INJECTION
2922 	REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
2923 #endif
2924 #ifdef CONFIG_ELF_CORE
2925 	REG("coredump_filter", S_IRUGO|S_IWUSR, proc_coredump_filter_operations),
2926 #endif
2927 #ifdef CONFIG_TASK_IO_ACCOUNTING
2928 	ONE("io",	S_IRUSR, proc_tgid_io_accounting),
2929 #endif
2930 #ifdef CONFIG_HARDWALL
2931 	ONE("hardwall",   S_IRUGO, proc_pid_hardwall),
2932 #endif
2933 #ifdef CONFIG_USER_NS
2934 	REG("uid_map",    S_IRUGO|S_IWUSR, proc_uid_map_operations),
2935 	REG("gid_map",    S_IRUGO|S_IWUSR, proc_gid_map_operations),
2936 	REG("projid_map", S_IRUGO|S_IWUSR, proc_projid_map_operations),
2937 	REG("setgroups",  S_IRUGO|S_IWUSR, proc_setgroups_operations),
2938 #endif
2939 #ifdef CONFIG_CHECKPOINT_RESTORE
2940 	REG("timers",	  S_IRUGO, proc_timers_operations),
2941 #endif
2942 	REG("timerslack_ns", S_IRUGO|S_IWUGO, proc_pid_set_timerslack_ns_operations),
2943 };
2944 
2945 static int proc_tgid_base_readdir(struct file *file, struct dir_context *ctx)
2946 {
2947 	return proc_pident_readdir(file, ctx,
2948 				   tgid_base_stuff, ARRAY_SIZE(tgid_base_stuff));
2949 }
2950 
2951 static const struct file_operations proc_tgid_base_operations = {
2952 	.read		= generic_read_dir,
2953 	.iterate_shared	= proc_tgid_base_readdir,
2954 	.llseek		= generic_file_llseek,
2955 };
2956 
2957 static struct dentry *proc_tgid_base_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
2958 {
2959 	return proc_pident_lookup(dir, dentry,
2960 				  tgid_base_stuff, ARRAY_SIZE(tgid_base_stuff));
2961 }
2962 
2963 static const struct inode_operations proc_tgid_base_inode_operations = {
2964 	.lookup		= proc_tgid_base_lookup,
2965 	.getattr	= pid_getattr,
2966 	.setattr	= proc_setattr,
2967 	.permission	= proc_pid_permission,
2968 };
2969 
2970 static void proc_flush_task_mnt(struct vfsmount *mnt, pid_t pid, pid_t tgid)
2971 {
2972 	struct dentry *dentry, *leader, *dir;
2973 	char buf[PROC_NUMBUF];
2974 	struct qstr name;
2975 
2976 	name.name = buf;
2977 	name.len = snprintf(buf, sizeof(buf), "%d", pid);
2978 	/* no ->d_hash() rejects on procfs */
2979 	dentry = d_hash_and_lookup(mnt->mnt_root, &name);
2980 	if (dentry) {
2981 		d_invalidate(dentry);
2982 		dput(dentry);
2983 	}
2984 
2985 	if (pid == tgid)
2986 		return;
2987 
2988 	name.name = buf;
2989 	name.len = snprintf(buf, sizeof(buf), "%d", tgid);
2990 	leader = d_hash_and_lookup(mnt->mnt_root, &name);
2991 	if (!leader)
2992 		goto out;
2993 
2994 	name.name = "task";
2995 	name.len = strlen(name.name);
2996 	dir = d_hash_and_lookup(leader, &name);
2997 	if (!dir)
2998 		goto out_put_leader;
2999 
3000 	name.name = buf;
3001 	name.len = snprintf(buf, sizeof(buf), "%d", pid);
3002 	dentry = d_hash_and_lookup(dir, &name);
3003 	if (dentry) {
3004 		d_invalidate(dentry);
3005 		dput(dentry);
3006 	}
3007 
3008 	dput(dir);
3009 out_put_leader:
3010 	dput(leader);
3011 out:
3012 	return;
3013 }
3014 
3015 /**
3016  * proc_flush_task -  Remove dcache entries for @task from the /proc dcache.
3017  * @task: task that should be flushed.
3018  *
3019  * When flushing dentries from proc, one needs to flush them from global
3020  * proc (proc_mnt) and from all the namespaces' procs this task was seen
3021  * in. This call is supposed to do all of this job.
3022  *
3023  * Looks in the dcache for
3024  * /proc/@pid
3025  * /proc/@tgid/task/@pid
3026  * if either directory is present flushes it and all of it'ts children
3027  * from the dcache.
3028  *
3029  * It is safe and reasonable to cache /proc entries for a task until
3030  * that task exits.  After that they just clog up the dcache with
3031  * useless entries, possibly causing useful dcache entries to be
3032  * flushed instead.  This routine is proved to flush those useless
3033  * dcache entries at process exit time.
3034  *
3035  * NOTE: This routine is just an optimization so it does not guarantee
3036  *       that no dcache entries will exist at process exit time it
3037  *       just makes it very unlikely that any will persist.
3038  */
3039 
3040 void proc_flush_task(struct task_struct *task)
3041 {
3042 	int i;
3043 	struct pid *pid, *tgid;
3044 	struct upid *upid;
3045 
3046 	pid = task_pid(task);
3047 	tgid = task_tgid(task);
3048 
3049 	for (i = 0; i <= pid->level; i++) {
3050 		upid = &pid->numbers[i];
3051 		proc_flush_task_mnt(upid->ns->proc_mnt, upid->nr,
3052 					tgid->numbers[i].nr);
3053 	}
3054 }
3055 
3056 static int proc_pid_instantiate(struct inode *dir,
3057 				   struct dentry * dentry,
3058 				   struct task_struct *task, const void *ptr)
3059 {
3060 	struct inode *inode;
3061 
3062 	inode = proc_pid_make_inode(dir->i_sb, task, S_IFDIR | S_IRUGO | S_IXUGO);
3063 	if (!inode)
3064 		goto out;
3065 
3066 	inode->i_op = &proc_tgid_base_inode_operations;
3067 	inode->i_fop = &proc_tgid_base_operations;
3068 	inode->i_flags|=S_IMMUTABLE;
3069 
3070 	set_nlink(inode, nlink_tgid);
3071 
3072 	d_set_d_op(dentry, &pid_dentry_operations);
3073 
3074 	d_add(dentry, inode);
3075 	/* Close the race of the process dying before we return the dentry */
3076 	if (pid_revalidate(dentry, 0))
3077 		return 0;
3078 out:
3079 	return -ENOENT;
3080 }
3081 
3082 struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)
3083 {
3084 	int result = -ENOENT;
3085 	struct task_struct *task;
3086 	unsigned tgid;
3087 	struct pid_namespace *ns;
3088 
3089 	tgid = name_to_int(&dentry->d_name);
3090 	if (tgid == ~0U)
3091 		goto out;
3092 
3093 	ns = dentry->d_sb->s_fs_info;
3094 	rcu_read_lock();
3095 	task = find_task_by_pid_ns(tgid, ns);
3096 	if (task)
3097 		get_task_struct(task);
3098 	rcu_read_unlock();
3099 	if (!task)
3100 		goto out;
3101 
3102 	result = proc_pid_instantiate(dir, dentry, task, NULL);
3103 	put_task_struct(task);
3104 out:
3105 	return ERR_PTR(result);
3106 }
3107 
3108 /*
3109  * Find the first task with tgid >= tgid
3110  *
3111  */
3112 struct tgid_iter {
3113 	unsigned int tgid;
3114 	struct task_struct *task;
3115 };
3116 static struct tgid_iter next_tgid(struct pid_namespace *ns, struct tgid_iter iter)
3117 {
3118 	struct pid *pid;
3119 
3120 	if (iter.task)
3121 		put_task_struct(iter.task);
3122 	rcu_read_lock();
3123 retry:
3124 	iter.task = NULL;
3125 	pid = find_ge_pid(iter.tgid, ns);
3126 	if (pid) {
3127 		iter.tgid = pid_nr_ns(pid, ns);
3128 		iter.task = pid_task(pid, PIDTYPE_PID);
3129 		/* What we to know is if the pid we have find is the
3130 		 * pid of a thread_group_leader.  Testing for task
3131 		 * being a thread_group_leader is the obvious thing
3132 		 * todo but there is a window when it fails, due to
3133 		 * the pid transfer logic in de_thread.
3134 		 *
3135 		 * So we perform the straight forward test of seeing
3136 		 * if the pid we have found is the pid of a thread
3137 		 * group leader, and don't worry if the task we have
3138 		 * found doesn't happen to be a thread group leader.
3139 		 * As we don't care in the case of readdir.
3140 		 */
3141 		if (!iter.task || !has_group_leader_pid(iter.task)) {
3142 			iter.tgid += 1;
3143 			goto retry;
3144 		}
3145 		get_task_struct(iter.task);
3146 	}
3147 	rcu_read_unlock();
3148 	return iter;
3149 }
3150 
3151 #define TGID_OFFSET (FIRST_PROCESS_ENTRY + 2)
3152 
3153 /* for the /proc/ directory itself, after non-process stuff has been done */
3154 int proc_pid_readdir(struct file *file, struct dir_context *ctx)
3155 {
3156 	struct tgid_iter iter;
3157 	struct pid_namespace *ns = file_inode(file)->i_sb->s_fs_info;
3158 	loff_t pos = ctx->pos;
3159 
3160 	if (pos >= PID_MAX_LIMIT + TGID_OFFSET)
3161 		return 0;
3162 
3163 	if (pos == TGID_OFFSET - 2) {
3164 		struct inode *inode = d_inode(ns->proc_self);
3165 		if (!dir_emit(ctx, "self", 4, inode->i_ino, DT_LNK))
3166 			return 0;
3167 		ctx->pos = pos = pos + 1;
3168 	}
3169 	if (pos == TGID_OFFSET - 1) {
3170 		struct inode *inode = d_inode(ns->proc_thread_self);
3171 		if (!dir_emit(ctx, "thread-self", 11, inode->i_ino, DT_LNK))
3172 			return 0;
3173 		ctx->pos = pos = pos + 1;
3174 	}
3175 	iter.tgid = pos - TGID_OFFSET;
3176 	iter.task = NULL;
3177 	for (iter = next_tgid(ns, iter);
3178 	     iter.task;
3179 	     iter.tgid += 1, iter = next_tgid(ns, iter)) {
3180 		char name[PROC_NUMBUF];
3181 		int len;
3182 		if (!has_pid_permissions(ns, iter.task, 2))
3183 			continue;
3184 
3185 		len = snprintf(name, sizeof(name), "%d", iter.tgid);
3186 		ctx->pos = iter.tgid + TGID_OFFSET;
3187 		if (!proc_fill_cache(file, ctx, name, len,
3188 				     proc_pid_instantiate, iter.task, NULL)) {
3189 			put_task_struct(iter.task);
3190 			return 0;
3191 		}
3192 	}
3193 	ctx->pos = PID_MAX_LIMIT + TGID_OFFSET;
3194 	return 0;
3195 }
3196 
3197 /*
3198  * proc_tid_comm_permission is a special permission function exclusively
3199  * used for the node /proc/<pid>/task/<tid>/comm.
3200  * It bypasses generic permission checks in the case where a task of the same
3201  * task group attempts to access the node.
3202  * The rationale behind this is that glibc and bionic access this node for
3203  * cross thread naming (pthread_set/getname_np(!self)). However, if
3204  * PR_SET_DUMPABLE gets set to 0 this node among others becomes uid=0 gid=0,
3205  * which locks out the cross thread naming implementation.
3206  * This function makes sure that the node is always accessible for members of
3207  * same thread group.
3208  */
3209 static int proc_tid_comm_permission(struct inode *inode, int mask)
3210 {
3211 	bool is_same_tgroup;
3212 	struct task_struct *task;
3213 
3214 	task = get_proc_task(inode);
3215 	if (!task)
3216 		return -ESRCH;
3217 	is_same_tgroup = same_thread_group(current, task);
3218 	put_task_struct(task);
3219 
3220 	if (likely(is_same_tgroup && !(mask & MAY_EXEC))) {
3221 		/* This file (/proc/<pid>/task/<tid>/comm) can always be
3222 		 * read or written by the members of the corresponding
3223 		 * thread group.
3224 		 */
3225 		return 0;
3226 	}
3227 
3228 	return generic_permission(inode, mask);
3229 }
3230 
3231 static const struct inode_operations proc_tid_comm_inode_operations = {
3232 		.permission = proc_tid_comm_permission,
3233 };
3234 
3235 /*
3236  * Tasks
3237  */
3238 static const struct pid_entry tid_base_stuff[] = {
3239 	DIR("fd",        S_IRUSR|S_IXUSR, proc_fd_inode_operations, proc_fd_operations),
3240 	DIR("fdinfo",    S_IRUSR|S_IXUSR, proc_fdinfo_inode_operations, proc_fdinfo_operations),
3241 	DIR("ns",	 S_IRUSR|S_IXUGO, proc_ns_dir_inode_operations, proc_ns_dir_operations),
3242 #ifdef CONFIG_NET
3243 	DIR("net",        S_IRUGO|S_IXUGO, proc_net_inode_operations, proc_net_operations),
3244 #endif
3245 	REG("environ",   S_IRUSR, proc_environ_operations),
3246 	REG("auxv",      S_IRUSR, proc_auxv_operations),
3247 	ONE("status",    S_IRUGO, proc_pid_status),
3248 	ONE("personality", S_IRUSR, proc_pid_personality),
3249 	ONE("limits",	 S_IRUGO, proc_pid_limits),
3250 #ifdef CONFIG_SCHED_DEBUG
3251 	REG("sched",     S_IRUGO|S_IWUSR, proc_pid_sched_operations),
3252 #endif
3253 	NOD("comm",      S_IFREG|S_IRUGO|S_IWUSR,
3254 			 &proc_tid_comm_inode_operations,
3255 			 &proc_pid_set_comm_operations, {}),
3256 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
3257 	ONE("syscall",   S_IRUSR, proc_pid_syscall),
3258 #endif
3259 	REG("cmdline",   S_IRUGO, proc_pid_cmdline_ops),
3260 	ONE("stat",      S_IRUGO, proc_tid_stat),
3261 	ONE("statm",     S_IRUGO, proc_pid_statm),
3262 	REG("maps",      S_IRUGO, proc_tid_maps_operations),
3263 #ifdef CONFIG_PROC_CHILDREN
3264 	REG("children",  S_IRUGO, proc_tid_children_operations),
3265 #endif
3266 #ifdef CONFIG_NUMA
3267 	REG("numa_maps", S_IRUGO, proc_tid_numa_maps_operations),
3268 #endif
3269 	REG("mem",       S_IRUSR|S_IWUSR, proc_mem_operations),
3270 	LNK("cwd",       proc_cwd_link),
3271 	LNK("root",      proc_root_link),
3272 	LNK("exe",       proc_exe_link),
3273 	REG("mounts",    S_IRUGO, proc_mounts_operations),
3274 	REG("mountinfo",  S_IRUGO, proc_mountinfo_operations),
3275 #ifdef CONFIG_PROC_PAGE_MONITOR
3276 	REG("clear_refs", S_IWUSR, proc_clear_refs_operations),
3277 	REG("smaps",     S_IRUGO, proc_tid_smaps_operations),
3278 	REG("pagemap",    S_IRUSR, proc_pagemap_operations),
3279 #endif
3280 #ifdef CONFIG_SECURITY
3281 	DIR("attr",      S_IRUGO|S_IXUGO, proc_attr_dir_inode_operations, proc_attr_dir_operations),
3282 #endif
3283 #ifdef CONFIG_KALLSYMS
3284 	ONE("wchan",     S_IRUGO, proc_pid_wchan),
3285 #endif
3286 #ifdef CONFIG_STACKTRACE
3287 	ONE("stack",      S_IRUSR, proc_pid_stack),
3288 #endif
3289 #ifdef CONFIG_SCHED_INFO
3290 	ONE("schedstat", S_IRUGO, proc_pid_schedstat),
3291 #endif
3292 #ifdef CONFIG_LATENCYTOP
3293 	REG("latency",  S_IRUGO, proc_lstats_operations),
3294 #endif
3295 #ifdef CONFIG_PROC_PID_CPUSET
3296 	ONE("cpuset",    S_IRUGO, proc_cpuset_show),
3297 #endif
3298 #ifdef CONFIG_CGROUPS
3299 	ONE("cgroup",  S_IRUGO, proc_cgroup_show),
3300 #endif
3301 	ONE("oom_score", S_IRUGO, proc_oom_score),
3302 	REG("oom_adj",   S_IRUGO|S_IWUSR, proc_oom_adj_operations),
3303 	REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
3304 #ifdef CONFIG_AUDITSYSCALL
3305 	REG("loginuid",  S_IWUSR|S_IRUGO, proc_loginuid_operations),
3306 	REG("sessionid",  S_IRUGO, proc_sessionid_operations),
3307 #endif
3308 #ifdef CONFIG_FAULT_INJECTION
3309 	REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
3310 #endif
3311 #ifdef CONFIG_TASK_IO_ACCOUNTING
3312 	ONE("io",	S_IRUSR, proc_tid_io_accounting),
3313 #endif
3314 #ifdef CONFIG_HARDWALL
3315 	ONE("hardwall",   S_IRUGO, proc_pid_hardwall),
3316 #endif
3317 #ifdef CONFIG_USER_NS
3318 	REG("uid_map",    S_IRUGO|S_IWUSR, proc_uid_map_operations),
3319 	REG("gid_map",    S_IRUGO|S_IWUSR, proc_gid_map_operations),
3320 	REG("projid_map", S_IRUGO|S_IWUSR, proc_projid_map_operations),
3321 	REG("setgroups",  S_IRUGO|S_IWUSR, proc_setgroups_operations),
3322 #endif
3323 };
3324 
3325 static int proc_tid_base_readdir(struct file *file, struct dir_context *ctx)
3326 {
3327 	return proc_pident_readdir(file, ctx,
3328 				   tid_base_stuff, ARRAY_SIZE(tid_base_stuff));
3329 }
3330 
3331 static struct dentry *proc_tid_base_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
3332 {
3333 	return proc_pident_lookup(dir, dentry,
3334 				  tid_base_stuff, ARRAY_SIZE(tid_base_stuff));
3335 }
3336 
3337 static const struct file_operations proc_tid_base_operations = {
3338 	.read		= generic_read_dir,
3339 	.iterate_shared	= proc_tid_base_readdir,
3340 	.llseek		= generic_file_llseek,
3341 };
3342 
3343 static const struct inode_operations proc_tid_base_inode_operations = {
3344 	.lookup		= proc_tid_base_lookup,
3345 	.getattr	= pid_getattr,
3346 	.setattr	= proc_setattr,
3347 };
3348 
3349 static int proc_task_instantiate(struct inode *dir,
3350 	struct dentry *dentry, struct task_struct *task, const void *ptr)
3351 {
3352 	struct inode *inode;
3353 	inode = proc_pid_make_inode(dir->i_sb, task, S_IFDIR | S_IRUGO | S_IXUGO);
3354 
3355 	if (!inode)
3356 		goto out;
3357 	inode->i_op = &proc_tid_base_inode_operations;
3358 	inode->i_fop = &proc_tid_base_operations;
3359 	inode->i_flags|=S_IMMUTABLE;
3360 
3361 	set_nlink(inode, nlink_tid);
3362 
3363 	d_set_d_op(dentry, &pid_dentry_operations);
3364 
3365 	d_add(dentry, inode);
3366 	/* Close the race of the process dying before we return the dentry */
3367 	if (pid_revalidate(dentry, 0))
3368 		return 0;
3369 out:
3370 	return -ENOENT;
3371 }
3372 
3373 static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)
3374 {
3375 	int result = -ENOENT;
3376 	struct task_struct *task;
3377 	struct task_struct *leader = get_proc_task(dir);
3378 	unsigned tid;
3379 	struct pid_namespace *ns;
3380 
3381 	if (!leader)
3382 		goto out_no_task;
3383 
3384 	tid = name_to_int(&dentry->d_name);
3385 	if (tid == ~0U)
3386 		goto out;
3387 
3388 	ns = dentry->d_sb->s_fs_info;
3389 	rcu_read_lock();
3390 	task = find_task_by_pid_ns(tid, ns);
3391 	if (task)
3392 		get_task_struct(task);
3393 	rcu_read_unlock();
3394 	if (!task)
3395 		goto out;
3396 	if (!same_thread_group(leader, task))
3397 		goto out_drop_task;
3398 
3399 	result = proc_task_instantiate(dir, dentry, task, NULL);
3400 out_drop_task:
3401 	put_task_struct(task);
3402 out:
3403 	put_task_struct(leader);
3404 out_no_task:
3405 	return ERR_PTR(result);
3406 }
3407 
3408 /*
3409  * Find the first tid of a thread group to return to user space.
3410  *
3411  * Usually this is just the thread group leader, but if the users
3412  * buffer was too small or there was a seek into the middle of the
3413  * directory we have more work todo.
3414  *
3415  * In the case of a short read we start with find_task_by_pid.
3416  *
3417  * In the case of a seek we start with the leader and walk nr
3418  * threads past it.
3419  */
3420 static struct task_struct *first_tid(struct pid *pid, int tid, loff_t f_pos,
3421 					struct pid_namespace *ns)
3422 {
3423 	struct task_struct *pos, *task;
3424 	unsigned long nr = f_pos;
3425 
3426 	if (nr != f_pos)	/* 32bit overflow? */
3427 		return NULL;
3428 
3429 	rcu_read_lock();
3430 	task = pid_task(pid, PIDTYPE_PID);
3431 	if (!task)
3432 		goto fail;
3433 
3434 	/* Attempt to start with the tid of a thread */
3435 	if (tid && nr) {
3436 		pos = find_task_by_pid_ns(tid, ns);
3437 		if (pos && same_thread_group(pos, task))
3438 			goto found;
3439 	}
3440 
3441 	/* If nr exceeds the number of threads there is nothing todo */
3442 	if (nr >= get_nr_threads(task))
3443 		goto fail;
3444 
3445 	/* If we haven't found our starting place yet start
3446 	 * with the leader and walk nr threads forward.
3447 	 */
3448 	pos = task = task->group_leader;
3449 	do {
3450 		if (!nr--)
3451 			goto found;
3452 	} while_each_thread(task, pos);
3453 fail:
3454 	pos = NULL;
3455 	goto out;
3456 found:
3457 	get_task_struct(pos);
3458 out:
3459 	rcu_read_unlock();
3460 	return pos;
3461 }
3462 
3463 /*
3464  * Find the next thread in the thread list.
3465  * Return NULL if there is an error or no next thread.
3466  *
3467  * The reference to the input task_struct is released.
3468  */
3469 static struct task_struct *next_tid(struct task_struct *start)
3470 {
3471 	struct task_struct *pos = NULL;
3472 	rcu_read_lock();
3473 	if (pid_alive(start)) {
3474 		pos = next_thread(start);
3475 		if (thread_group_leader(pos))
3476 			pos = NULL;
3477 		else
3478 			get_task_struct(pos);
3479 	}
3480 	rcu_read_unlock();
3481 	put_task_struct(start);
3482 	return pos;
3483 }
3484 
3485 /* for the /proc/TGID/task/ directories */
3486 static int proc_task_readdir(struct file *file, struct dir_context *ctx)
3487 {
3488 	struct inode *inode = file_inode(file);
3489 	struct task_struct *task;
3490 	struct pid_namespace *ns;
3491 	int tid;
3492 
3493 	if (proc_inode_is_dead(inode))
3494 		return -ENOENT;
3495 
3496 	if (!dir_emit_dots(file, ctx))
3497 		return 0;
3498 
3499 	/* f_version caches the tgid value that the last readdir call couldn't
3500 	 * return. lseek aka telldir automagically resets f_version to 0.
3501 	 */
3502 	ns = inode->i_sb->s_fs_info;
3503 	tid = (int)file->f_version;
3504 	file->f_version = 0;
3505 	for (task = first_tid(proc_pid(inode), tid, ctx->pos - 2, ns);
3506 	     task;
3507 	     task = next_tid(task), ctx->pos++) {
3508 		char name[PROC_NUMBUF];
3509 		int len;
3510 		tid = task_pid_nr_ns(task, ns);
3511 		len = snprintf(name, sizeof(name), "%d", tid);
3512 		if (!proc_fill_cache(file, ctx, name, len,
3513 				proc_task_instantiate, task, NULL)) {
3514 			/* returning this tgid failed, save it as the first
3515 			 * pid for the next readir call */
3516 			file->f_version = (u64)tid;
3517 			put_task_struct(task);
3518 			break;
3519 		}
3520 	}
3521 
3522 	return 0;
3523 }
3524 
3525 static int proc_task_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
3526 {
3527 	struct inode *inode = d_inode(dentry);
3528 	struct task_struct *p = get_proc_task(inode);
3529 	generic_fillattr(inode, stat);
3530 
3531 	if (p) {
3532 		stat->nlink += get_nr_threads(p);
3533 		put_task_struct(p);
3534 	}
3535 
3536 	return 0;
3537 }
3538 
3539 static const struct inode_operations proc_task_inode_operations = {
3540 	.lookup		= proc_task_lookup,
3541 	.getattr	= proc_task_getattr,
3542 	.setattr	= proc_setattr,
3543 	.permission	= proc_pid_permission,
3544 };
3545 
3546 static const struct file_operations proc_task_operations = {
3547 	.read		= generic_read_dir,
3548 	.iterate_shared	= proc_task_readdir,
3549 	.llseek		= generic_file_llseek,
3550 };
3551 
3552 void __init set_proc_pid_nlink(void)
3553 {
3554 	nlink_tid = pid_entry_nlink(tid_base_stuff, ARRAY_SIZE(tid_base_stuff));
3555 	nlink_tgid = pid_entry_nlink(tgid_base_stuff, ARRAY_SIZE(tgid_base_stuff));
3556 }
3557