xref: /openbmc/linux/fs/proc/base.c (revision fa7f32422ea1ac276b45b96a540ed5981caaa61f)
1 /*
2  *  linux/fs/proc/base.c
3  *
4  *  Copyright (C) 1991, 1992 Linus Torvalds
5  *
6  *  proc base directory handling functions
7  *
8  *  1999, Al Viro. Rewritten. Now it covers the whole per-process part.
9  *  Instead of using magical inumbers to determine the kind of object
10  *  we allocate and fill in-core inodes upon lookup. They don't even
11  *  go into icache. We cache the reference to task_struct upon lookup too.
12  *  Eventually it should become a filesystem in its own. We don't use the
13  *  rest of procfs anymore.
14  *
15  *
16  *  Changelog:
17  *  17-Jan-2005
18  *  Allan Bezerra
19  *  Bruna Moreira <bruna.moreira@indt.org.br>
20  *  Edjard Mota <edjard.mota@indt.org.br>
21  *  Ilias Biris <ilias.biris@indt.org.br>
22  *  Mauricio Lin <mauricio.lin@indt.org.br>
23  *
24  *  Embedded Linux Lab - 10LE Instituto Nokia de Tecnologia - INdT
25  *
26  *  A new process specific entry (smaps) included in /proc. It shows the
27  *  size of rss for each memory area. The maps entry lacks information
28  *  about physical memory size (rss) for each mapped file, i.e.,
29  *  rss information for executables and library files.
30  *  This additional information is useful for any tools that need to know
31  *  about physical memory consumption for a process specific library.
32  *
33  *  Changelog:
34  *  21-Feb-2005
35  *  Embedded Linux Lab - 10LE Instituto Nokia de Tecnologia - INdT
36  *  Pud inclusion in the page table walking.
37  *
38  *  ChangeLog:
39  *  10-Mar-2005
40  *  10LE Instituto Nokia de Tecnologia - INdT:
41  *  A better way to walks through the page table as suggested by Hugh Dickins.
42  *
43  *  Simo Piiroinen <simo.piiroinen@nokia.com>:
44  *  Smaps information related to shared, private, clean and dirty pages.
45  *
46  *  Paul Mundt <paul.mundt@nokia.com>:
47  *  Overall revision about smaps.
48  */
49 
50 #include <asm/uaccess.h>
51 
52 #include <linux/errno.h>
53 #include <linux/time.h>
54 #include <linux/proc_fs.h>
55 #include <linux/stat.h>
56 #include <linux/task_io_accounting_ops.h>
57 #include <linux/init.h>
58 #include <linux/capability.h>
59 #include <linux/file.h>
60 #include <linux/fdtable.h>
61 #include <linux/string.h>
62 #include <linux/seq_file.h>
63 #include <linux/namei.h>
64 #include <linux/mnt_namespace.h>
65 #include <linux/mm.h>
66 #include <linux/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 struct pid_entry {
108 	const char *name;
109 	int len;
110 	umode_t mode;
111 	const struct inode_operations *iop;
112 	const struct file_operations *fop;
113 	union proc_op op;
114 };
115 
116 #define NOD(NAME, MODE, IOP, FOP, OP) {			\
117 	.name = (NAME),					\
118 	.len  = sizeof(NAME) - 1,			\
119 	.mode = MODE,					\
120 	.iop  = IOP,					\
121 	.fop  = FOP,					\
122 	.op   = OP,					\
123 }
124 
125 #define DIR(NAME, MODE, iops, fops)	\
126 	NOD(NAME, (S_IFDIR|(MODE)), &iops, &fops, {} )
127 #define LNK(NAME, get_link)					\
128 	NOD(NAME, (S_IFLNK|S_IRWXUGO),				\
129 		&proc_pid_link_inode_operations, NULL,		\
130 		{ .proc_get_link = get_link } )
131 #define REG(NAME, MODE, fops)				\
132 	NOD(NAME, (S_IFREG|(MODE)), NULL, &fops, {})
133 #define ONE(NAME, MODE, show)				\
134 	NOD(NAME, (S_IFREG|(MODE)), 			\
135 		NULL, &proc_single_file_operations,	\
136 		{ .proc_show = show } )
137 
138 /*
139  * Count the number of hardlinks for the pid_entry table, excluding the .
140  * and .. links.
141  */
142 static unsigned int pid_entry_count_dirs(const struct pid_entry *entries,
143 	unsigned int n)
144 {
145 	unsigned int i;
146 	unsigned int count;
147 
148 	count = 0;
149 	for (i = 0; i < n; ++i) {
150 		if (S_ISDIR(entries[i].mode))
151 			++count;
152 	}
153 
154 	return count;
155 }
156 
157 static int get_task_root(struct task_struct *task, struct path *root)
158 {
159 	int result = -ENOENT;
160 
161 	task_lock(task);
162 	if (task->fs) {
163 		get_fs_root(task->fs, root);
164 		result = 0;
165 	}
166 	task_unlock(task);
167 	return result;
168 }
169 
170 static int proc_cwd_link(struct dentry *dentry, struct path *path)
171 {
172 	struct task_struct *task = get_proc_task(d_inode(dentry));
173 	int result = -ENOENT;
174 
175 	if (task) {
176 		task_lock(task);
177 		if (task->fs) {
178 			get_fs_pwd(task->fs, path);
179 			result = 0;
180 		}
181 		task_unlock(task);
182 		put_task_struct(task);
183 	}
184 	return result;
185 }
186 
187 static int proc_root_link(struct dentry *dentry, struct path *path)
188 {
189 	struct task_struct *task = get_proc_task(d_inode(dentry));
190 	int result = -ENOENT;
191 
192 	if (task) {
193 		result = get_task_root(task, path);
194 		put_task_struct(task);
195 	}
196 	return result;
197 }
198 
199 static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
200 				     size_t _count, loff_t *pos)
201 {
202 	struct task_struct *tsk;
203 	struct mm_struct *mm;
204 	char *page;
205 	unsigned long count = _count;
206 	unsigned long arg_start, arg_end, env_start, env_end;
207 	unsigned long len1, len2, len;
208 	unsigned long p;
209 	char c;
210 	ssize_t rv;
211 
212 	BUG_ON(*pos < 0);
213 
214 	tsk = get_proc_task(file_inode(file));
215 	if (!tsk)
216 		return -ESRCH;
217 	mm = get_task_mm(tsk);
218 	put_task_struct(tsk);
219 	if (!mm)
220 		return 0;
221 	/* Check if process spawned far enough to have cmdline. */
222 	if (!mm->env_end) {
223 		rv = 0;
224 		goto out_mmput;
225 	}
226 
227 	page = (char *)__get_free_page(GFP_TEMPORARY);
228 	if (!page) {
229 		rv = -ENOMEM;
230 		goto out_mmput;
231 	}
232 
233 	down_read(&mm->mmap_sem);
234 	arg_start = mm->arg_start;
235 	arg_end = mm->arg_end;
236 	env_start = mm->env_start;
237 	env_end = mm->env_end;
238 	up_read(&mm->mmap_sem);
239 
240 	BUG_ON(arg_start > arg_end);
241 	BUG_ON(env_start > env_end);
242 
243 	len1 = arg_end - arg_start;
244 	len2 = env_end - env_start;
245 
246 	/* Empty ARGV. */
247 	if (len1 == 0) {
248 		rv = 0;
249 		goto out_free_page;
250 	}
251 	/*
252 	 * Inherently racy -- command line shares address space
253 	 * with code and data.
254 	 */
255 	rv = access_remote_vm(mm, arg_end - 1, &c, 1, 0);
256 	if (rv <= 0)
257 		goto out_free_page;
258 
259 	rv = 0;
260 
261 	if (c == '\0') {
262 		/* Command line (set of strings) occupies whole ARGV. */
263 		if (len1 <= *pos)
264 			goto out_free_page;
265 
266 		p = arg_start + *pos;
267 		len = len1 - *pos;
268 		while (count > 0 && len > 0) {
269 			unsigned int _count;
270 			int nr_read;
271 
272 			_count = min3(count, len, PAGE_SIZE);
273 			nr_read = access_remote_vm(mm, p, page, _count, 0);
274 			if (nr_read < 0)
275 				rv = nr_read;
276 			if (nr_read <= 0)
277 				goto out_free_page;
278 
279 			if (copy_to_user(buf, page, nr_read)) {
280 				rv = -EFAULT;
281 				goto out_free_page;
282 			}
283 
284 			p	+= nr_read;
285 			len	-= nr_read;
286 			buf	+= nr_read;
287 			count	-= nr_read;
288 			rv	+= nr_read;
289 		}
290 	} else {
291 		/*
292 		 * Command line (1 string) occupies ARGV and maybe
293 		 * extends into ENVP.
294 		 */
295 		if (len1 + len2 <= *pos)
296 			goto skip_argv_envp;
297 		if (len1 <= *pos)
298 			goto skip_argv;
299 
300 		p = arg_start + *pos;
301 		len = len1 - *pos;
302 		while (count > 0 && len > 0) {
303 			unsigned int _count, l;
304 			int nr_read;
305 			bool final;
306 
307 			_count = min3(count, len, PAGE_SIZE);
308 			nr_read = access_remote_vm(mm, p, page, _count, 0);
309 			if (nr_read < 0)
310 				rv = nr_read;
311 			if (nr_read <= 0)
312 				goto out_free_page;
313 
314 			/*
315 			 * Command line can be shorter than whole ARGV
316 			 * even if last "marker" byte says it is not.
317 			 */
318 			final = false;
319 			l = strnlen(page, nr_read);
320 			if (l < nr_read) {
321 				nr_read = l;
322 				final = true;
323 			}
324 
325 			if (copy_to_user(buf, page, nr_read)) {
326 				rv = -EFAULT;
327 				goto out_free_page;
328 			}
329 
330 			p	+= nr_read;
331 			len	-= nr_read;
332 			buf	+= nr_read;
333 			count	-= nr_read;
334 			rv	+= nr_read;
335 
336 			if (final)
337 				goto out_free_page;
338 		}
339 skip_argv:
340 		/*
341 		 * Command line (1 string) occupies ARGV and
342 		 * extends into ENVP.
343 		 */
344 		if (len1 <= *pos) {
345 			p = env_start + *pos - len1;
346 			len = len1 + len2 - *pos;
347 		} else {
348 			p = env_start;
349 			len = len2;
350 		}
351 		while (count > 0 && len > 0) {
352 			unsigned int _count, l;
353 			int nr_read;
354 			bool final;
355 
356 			_count = min3(count, len, PAGE_SIZE);
357 			nr_read = access_remote_vm(mm, p, page, _count, 0);
358 			if (nr_read < 0)
359 				rv = nr_read;
360 			if (nr_read <= 0)
361 				goto out_free_page;
362 
363 			/* Find EOS. */
364 			final = false;
365 			l = strnlen(page, nr_read);
366 			if (l < nr_read) {
367 				nr_read = l;
368 				final = true;
369 			}
370 
371 			if (copy_to_user(buf, page, nr_read)) {
372 				rv = -EFAULT;
373 				goto out_free_page;
374 			}
375 
376 			p	+= nr_read;
377 			len	-= nr_read;
378 			buf	+= nr_read;
379 			count	-= nr_read;
380 			rv	+= nr_read;
381 
382 			if (final)
383 				goto out_free_page;
384 		}
385 skip_argv_envp:
386 		;
387 	}
388 
389 out_free_page:
390 	free_page((unsigned long)page);
391 out_mmput:
392 	mmput(mm);
393 	if (rv > 0)
394 		*pos += rv;
395 	return rv;
396 }
397 
398 static const struct file_operations proc_pid_cmdline_ops = {
399 	.read	= proc_pid_cmdline_read,
400 	.llseek	= generic_file_llseek,
401 };
402 
403 #ifdef CONFIG_KALLSYMS
404 /*
405  * Provides a wchan file via kallsyms in a proper one-value-per-file format.
406  * Returns the resolved symbol.  If that fails, simply return the address.
407  */
408 static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns,
409 			  struct pid *pid, struct task_struct *task)
410 {
411 	unsigned long wchan;
412 	char symname[KSYM_NAME_LEN];
413 
414 	wchan = get_wchan(task);
415 
416 	if (wchan && ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)
417 			&& !lookup_symbol_name(wchan, symname))
418 		seq_printf(m, "%s", symname);
419 	else
420 		seq_putc(m, '0');
421 
422 	return 0;
423 }
424 #endif /* CONFIG_KALLSYMS */
425 
426 static int lock_trace(struct task_struct *task)
427 {
428 	int err = mutex_lock_killable(&task->signal->cred_guard_mutex);
429 	if (err)
430 		return err;
431 	if (!ptrace_may_access(task, PTRACE_MODE_ATTACH_FSCREDS)) {
432 		mutex_unlock(&task->signal->cred_guard_mutex);
433 		return -EPERM;
434 	}
435 	return 0;
436 }
437 
438 static void unlock_trace(struct task_struct *task)
439 {
440 	mutex_unlock(&task->signal->cred_guard_mutex);
441 }
442 
443 #ifdef CONFIG_STACKTRACE
444 
445 #define MAX_STACK_TRACE_DEPTH	64
446 
447 static int proc_pid_stack(struct seq_file *m, struct pid_namespace *ns,
448 			  struct pid *pid, struct task_struct *task)
449 {
450 	struct stack_trace trace;
451 	unsigned long *entries;
452 	int err;
453 	int i;
454 
455 	entries = kmalloc(MAX_STACK_TRACE_DEPTH * sizeof(*entries), GFP_KERNEL);
456 	if (!entries)
457 		return -ENOMEM;
458 
459 	trace.nr_entries	= 0;
460 	trace.max_entries	= MAX_STACK_TRACE_DEPTH;
461 	trace.entries		= entries;
462 	trace.skip		= 0;
463 
464 	err = lock_trace(task);
465 	if (!err) {
466 		save_stack_trace_tsk(task, &trace);
467 
468 		for (i = 0; i < trace.nr_entries; i++) {
469 			seq_printf(m, "[<%pK>] %pB\n",
470 				   (void *)entries[i], (void *)entries[i]);
471 		}
472 		unlock_trace(task);
473 	}
474 	kfree(entries);
475 
476 	return err;
477 }
478 #endif
479 
480 #ifdef CONFIG_SCHED_INFO
481 /*
482  * Provides /proc/PID/schedstat
483  */
484 static int proc_pid_schedstat(struct seq_file *m, struct pid_namespace *ns,
485 			      struct pid *pid, struct task_struct *task)
486 {
487 	if (unlikely(!sched_info_on()))
488 		seq_printf(m, "0 0 0\n");
489 	else
490 		seq_printf(m, "%llu %llu %lu\n",
491 		   (unsigned long long)task->se.sum_exec_runtime,
492 		   (unsigned long long)task->sched_info.run_delay,
493 		   task->sched_info.pcount);
494 
495 	return 0;
496 }
497 #endif
498 
499 #ifdef CONFIG_LATENCYTOP
500 static int lstats_show_proc(struct seq_file *m, void *v)
501 {
502 	int i;
503 	struct inode *inode = m->private;
504 	struct task_struct *task = get_proc_task(inode);
505 
506 	if (!task)
507 		return -ESRCH;
508 	seq_puts(m, "Latency Top version : v0.1\n");
509 	for (i = 0; i < 32; i++) {
510 		struct latency_record *lr = &task->latency_record[i];
511 		if (lr->backtrace[0]) {
512 			int q;
513 			seq_printf(m, "%i %li %li",
514 				   lr->count, lr->time, lr->max);
515 			for (q = 0; q < LT_BACKTRACEDEPTH; q++) {
516 				unsigned long bt = lr->backtrace[q];
517 				if (!bt)
518 					break;
519 				if (bt == ULONG_MAX)
520 					break;
521 				seq_printf(m, " %ps", (void *)bt);
522 			}
523 			seq_putc(m, '\n');
524 		}
525 
526 	}
527 	put_task_struct(task);
528 	return 0;
529 }
530 
531 static int lstats_open(struct inode *inode, struct file *file)
532 {
533 	return single_open(file, lstats_show_proc, inode);
534 }
535 
536 static ssize_t lstats_write(struct file *file, const char __user *buf,
537 			    size_t count, loff_t *offs)
538 {
539 	struct task_struct *task = get_proc_task(file_inode(file));
540 
541 	if (!task)
542 		return -ESRCH;
543 	clear_all_latency_tracing(task);
544 	put_task_struct(task);
545 
546 	return count;
547 }
548 
549 static const struct file_operations proc_lstats_operations = {
550 	.open		= lstats_open,
551 	.read		= seq_read,
552 	.write		= lstats_write,
553 	.llseek		= seq_lseek,
554 	.release	= single_release,
555 };
556 
557 #endif
558 
559 static int proc_oom_score(struct seq_file *m, struct pid_namespace *ns,
560 			  struct pid *pid, struct task_struct *task)
561 {
562 	unsigned long totalpages = totalram_pages + total_swap_pages;
563 	unsigned long points = 0;
564 
565 	points = oom_badness(task, NULL, NULL, totalpages) *
566 					1000 / totalpages;
567 	seq_printf(m, "%lu\n", points);
568 
569 	return 0;
570 }
571 
572 struct limit_names {
573 	const char *name;
574 	const char *unit;
575 };
576 
577 static const struct limit_names lnames[RLIM_NLIMITS] = {
578 	[RLIMIT_CPU] = {"Max cpu time", "seconds"},
579 	[RLIMIT_FSIZE] = {"Max file size", "bytes"},
580 	[RLIMIT_DATA] = {"Max data size", "bytes"},
581 	[RLIMIT_STACK] = {"Max stack size", "bytes"},
582 	[RLIMIT_CORE] = {"Max core file size", "bytes"},
583 	[RLIMIT_RSS] = {"Max resident set", "bytes"},
584 	[RLIMIT_NPROC] = {"Max processes", "processes"},
585 	[RLIMIT_NOFILE] = {"Max open files", "files"},
586 	[RLIMIT_MEMLOCK] = {"Max locked memory", "bytes"},
587 	[RLIMIT_AS] = {"Max address space", "bytes"},
588 	[RLIMIT_LOCKS] = {"Max file locks", "locks"},
589 	[RLIMIT_SIGPENDING] = {"Max pending signals", "signals"},
590 	[RLIMIT_MSGQUEUE] = {"Max msgqueue size", "bytes"},
591 	[RLIMIT_NICE] = {"Max nice priority", NULL},
592 	[RLIMIT_RTPRIO] = {"Max realtime priority", NULL},
593 	[RLIMIT_RTTIME] = {"Max realtime timeout", "us"},
594 };
595 
596 /* Display limits for a process */
597 static int proc_pid_limits(struct seq_file *m, struct pid_namespace *ns,
598 			   struct pid *pid, struct task_struct *task)
599 {
600 	unsigned int i;
601 	unsigned long flags;
602 
603 	struct rlimit rlim[RLIM_NLIMITS];
604 
605 	if (!lock_task_sighand(task, &flags))
606 		return 0;
607 	memcpy(rlim, task->signal->rlim, sizeof(struct rlimit) * RLIM_NLIMITS);
608 	unlock_task_sighand(task, &flags);
609 
610 	/*
611 	 * print the file header
612 	 */
613        seq_printf(m, "%-25s %-20s %-20s %-10s\n",
614 		  "Limit", "Soft Limit", "Hard Limit", "Units");
615 
616 	for (i = 0; i < RLIM_NLIMITS; i++) {
617 		if (rlim[i].rlim_cur == RLIM_INFINITY)
618 			seq_printf(m, "%-25s %-20s ",
619 				   lnames[i].name, "unlimited");
620 		else
621 			seq_printf(m, "%-25s %-20lu ",
622 				   lnames[i].name, rlim[i].rlim_cur);
623 
624 		if (rlim[i].rlim_max == RLIM_INFINITY)
625 			seq_printf(m, "%-20s ", "unlimited");
626 		else
627 			seq_printf(m, "%-20lu ", rlim[i].rlim_max);
628 
629 		if (lnames[i].unit)
630 			seq_printf(m, "%-10s\n", lnames[i].unit);
631 		else
632 			seq_putc(m, '\n');
633 	}
634 
635 	return 0;
636 }
637 
638 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
639 static int proc_pid_syscall(struct seq_file *m, struct pid_namespace *ns,
640 			    struct pid *pid, struct task_struct *task)
641 {
642 	long nr;
643 	unsigned long args[6], sp, pc;
644 	int res;
645 
646 	res = lock_trace(task);
647 	if (res)
648 		return res;
649 
650 	if (task_current_syscall(task, &nr, args, 6, &sp, &pc))
651 		seq_puts(m, "running\n");
652 	else if (nr < 0)
653 		seq_printf(m, "%ld 0x%lx 0x%lx\n", nr, sp, pc);
654 	else
655 		seq_printf(m,
656 		       "%ld 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx\n",
657 		       nr,
658 		       args[0], args[1], args[2], args[3], args[4], args[5],
659 		       sp, pc);
660 	unlock_trace(task);
661 
662 	return 0;
663 }
664 #endif /* CONFIG_HAVE_ARCH_TRACEHOOK */
665 
666 /************************************************************************/
667 /*                       Here the fs part begins                        */
668 /************************************************************************/
669 
670 /* permission checks */
671 static int proc_fd_access_allowed(struct inode *inode)
672 {
673 	struct task_struct *task;
674 	int allowed = 0;
675 	/* Allow access to a task's file descriptors if it is us or we
676 	 * may use ptrace attach to the process and find out that
677 	 * information.
678 	 */
679 	task = get_proc_task(inode);
680 	if (task) {
681 		allowed = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
682 		put_task_struct(task);
683 	}
684 	return allowed;
685 }
686 
687 int proc_setattr(struct dentry *dentry, struct iattr *attr)
688 {
689 	int error;
690 	struct inode *inode = d_inode(dentry);
691 
692 	if (attr->ia_valid & ATTR_MODE)
693 		return -EPERM;
694 
695 	error = setattr_prepare(dentry, attr);
696 	if (error)
697 		return error;
698 
699 	setattr_copy(inode, attr);
700 	mark_inode_dirty(inode);
701 	return 0;
702 }
703 
704 /*
705  * May current process learn task's sched/cmdline info (for hide_pid_min=1)
706  * or euid/egid (for hide_pid_min=2)?
707  */
708 static bool has_pid_permissions(struct pid_namespace *pid,
709 				 struct task_struct *task,
710 				 int hide_pid_min)
711 {
712 	if (pid->hide_pid < hide_pid_min)
713 		return true;
714 	if (in_group_p(pid->pid_gid))
715 		return true;
716 	return ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
717 }
718 
719 
720 static int proc_pid_permission(struct inode *inode, int mask)
721 {
722 	struct pid_namespace *pid = inode->i_sb->s_fs_info;
723 	struct task_struct *task;
724 	bool has_perms;
725 
726 	task = get_proc_task(inode);
727 	if (!task)
728 		return -ESRCH;
729 	has_perms = has_pid_permissions(pid, task, 1);
730 	put_task_struct(task);
731 
732 	if (!has_perms) {
733 		if (pid->hide_pid == 2) {
734 			/*
735 			 * Let's make getdents(), stat(), and open()
736 			 * consistent with each other.  If a process
737 			 * may not stat() a file, it shouldn't be seen
738 			 * in procfs at all.
739 			 */
740 			return -ENOENT;
741 		}
742 
743 		return -EPERM;
744 	}
745 	return generic_permission(inode, mask);
746 }
747 
748 
749 
750 static const struct inode_operations proc_def_inode_operations = {
751 	.setattr	= proc_setattr,
752 };
753 
754 static int proc_single_show(struct seq_file *m, void *v)
755 {
756 	struct inode *inode = m->private;
757 	struct pid_namespace *ns;
758 	struct pid *pid;
759 	struct task_struct *task;
760 	int ret;
761 
762 	ns = inode->i_sb->s_fs_info;
763 	pid = proc_pid(inode);
764 	task = get_pid_task(pid, PIDTYPE_PID);
765 	if (!task)
766 		return -ESRCH;
767 
768 	ret = PROC_I(inode)->op.proc_show(m, ns, pid, task);
769 
770 	put_task_struct(task);
771 	return ret;
772 }
773 
774 static int proc_single_open(struct inode *inode, struct file *filp)
775 {
776 	return single_open(filp, proc_single_show, inode);
777 }
778 
779 static const struct file_operations proc_single_file_operations = {
780 	.open		= proc_single_open,
781 	.read		= seq_read,
782 	.llseek		= seq_lseek,
783 	.release	= single_release,
784 };
785 
786 
787 struct mm_struct *proc_mem_open(struct inode *inode, unsigned int mode)
788 {
789 	struct task_struct *task = get_proc_task(inode);
790 	struct mm_struct *mm = ERR_PTR(-ESRCH);
791 
792 	if (task) {
793 		mm = mm_access(task, mode | PTRACE_MODE_FSCREDS);
794 		put_task_struct(task);
795 
796 		if (!IS_ERR_OR_NULL(mm)) {
797 			/* ensure this mm_struct can't be freed */
798 			atomic_inc(&mm->mm_count);
799 			/* but do not pin its memory */
800 			mmput(mm);
801 		}
802 	}
803 
804 	return mm;
805 }
806 
807 static int __mem_open(struct inode *inode, struct file *file, unsigned int mode)
808 {
809 	struct mm_struct *mm = proc_mem_open(inode, mode);
810 
811 	if (IS_ERR(mm))
812 		return PTR_ERR(mm);
813 
814 	file->private_data = mm;
815 	return 0;
816 }
817 
818 static int mem_open(struct inode *inode, struct file *file)
819 {
820 	int ret = __mem_open(inode, file, PTRACE_MODE_ATTACH);
821 
822 	/* OK to pass negative loff_t, we can catch out-of-range */
823 	file->f_mode |= FMODE_UNSIGNED_OFFSET;
824 
825 	return ret;
826 }
827 
828 static ssize_t mem_rw(struct file *file, char __user *buf,
829 			size_t count, loff_t *ppos, int write)
830 {
831 	struct mm_struct *mm = file->private_data;
832 	unsigned long addr = *ppos;
833 	ssize_t copied;
834 	char *page;
835 
836 	if (!mm)
837 		return 0;
838 
839 	page = (char *)__get_free_page(GFP_TEMPORARY);
840 	if (!page)
841 		return -ENOMEM;
842 
843 	copied = 0;
844 	if (!atomic_inc_not_zero(&mm->mm_users))
845 		goto free;
846 
847 	while (count > 0) {
848 		int this_len = min_t(int, count, PAGE_SIZE);
849 
850 		if (write && copy_from_user(page, buf, this_len)) {
851 			copied = -EFAULT;
852 			break;
853 		}
854 
855 		this_len = access_remote_vm(mm, addr, page, this_len, write);
856 		if (!this_len) {
857 			if (!copied)
858 				copied = -EIO;
859 			break;
860 		}
861 
862 		if (!write && copy_to_user(buf, page, this_len)) {
863 			copied = -EFAULT;
864 			break;
865 		}
866 
867 		buf += this_len;
868 		addr += this_len;
869 		copied += this_len;
870 		count -= this_len;
871 	}
872 	*ppos = addr;
873 
874 	mmput(mm);
875 free:
876 	free_page((unsigned long) page);
877 	return copied;
878 }
879 
880 static ssize_t mem_read(struct file *file, char __user *buf,
881 			size_t count, loff_t *ppos)
882 {
883 	return mem_rw(file, buf, count, ppos, 0);
884 }
885 
886 static ssize_t mem_write(struct file *file, const char __user *buf,
887 			 size_t count, loff_t *ppos)
888 {
889 	return mem_rw(file, (char __user*)buf, count, ppos, 1);
890 }
891 
892 loff_t mem_lseek(struct file *file, loff_t offset, int orig)
893 {
894 	switch (orig) {
895 	case 0:
896 		file->f_pos = offset;
897 		break;
898 	case 1:
899 		file->f_pos += offset;
900 		break;
901 	default:
902 		return -EINVAL;
903 	}
904 	force_successful_syscall_return();
905 	return file->f_pos;
906 }
907 
908 static int mem_release(struct inode *inode, struct file *file)
909 {
910 	struct mm_struct *mm = file->private_data;
911 	if (mm)
912 		mmdrop(mm);
913 	return 0;
914 }
915 
916 static const struct file_operations proc_mem_operations = {
917 	.llseek		= mem_lseek,
918 	.read		= mem_read,
919 	.write		= mem_write,
920 	.open		= mem_open,
921 	.release	= mem_release,
922 };
923 
924 static int environ_open(struct inode *inode, struct file *file)
925 {
926 	return __mem_open(inode, file, PTRACE_MODE_READ);
927 }
928 
929 static ssize_t environ_read(struct file *file, char __user *buf,
930 			size_t count, loff_t *ppos)
931 {
932 	char *page;
933 	unsigned long src = *ppos;
934 	int ret = 0;
935 	struct mm_struct *mm = file->private_data;
936 	unsigned long env_start, env_end;
937 
938 	/* Ensure the process spawned far enough to have an environment. */
939 	if (!mm || !mm->env_end)
940 		return 0;
941 
942 	page = (char *)__get_free_page(GFP_TEMPORARY);
943 	if (!page)
944 		return -ENOMEM;
945 
946 	ret = 0;
947 	if (!atomic_inc_not_zero(&mm->mm_users))
948 		goto free;
949 
950 	down_read(&mm->mmap_sem);
951 	env_start = mm->env_start;
952 	env_end = mm->env_end;
953 	up_read(&mm->mmap_sem);
954 
955 	while (count > 0) {
956 		size_t this_len, max_len;
957 		int retval;
958 
959 		if (src >= (env_end - env_start))
960 			break;
961 
962 		this_len = env_end - (env_start + src);
963 
964 		max_len = min_t(size_t, PAGE_SIZE, count);
965 		this_len = min(max_len, this_len);
966 
967 		retval = access_remote_vm(mm, (env_start + src),
968 			page, this_len, 0);
969 
970 		if (retval <= 0) {
971 			ret = retval;
972 			break;
973 		}
974 
975 		if (copy_to_user(buf, page, retval)) {
976 			ret = -EFAULT;
977 			break;
978 		}
979 
980 		ret += retval;
981 		src += retval;
982 		buf += retval;
983 		count -= retval;
984 	}
985 	*ppos = src;
986 	mmput(mm);
987 
988 free:
989 	free_page((unsigned long) page);
990 	return ret;
991 }
992 
993 static const struct file_operations proc_environ_operations = {
994 	.open		= environ_open,
995 	.read		= environ_read,
996 	.llseek		= generic_file_llseek,
997 	.release	= mem_release,
998 };
999 
1000 static int auxv_open(struct inode *inode, struct file *file)
1001 {
1002 	return __mem_open(inode, file, PTRACE_MODE_READ_FSCREDS);
1003 }
1004 
1005 static ssize_t auxv_read(struct file *file, char __user *buf,
1006 			size_t count, loff_t *ppos)
1007 {
1008 	struct mm_struct *mm = file->private_data;
1009 	unsigned int nwords = 0;
1010 	do {
1011 		nwords += 2;
1012 	} while (mm->saved_auxv[nwords - 2] != 0); /* AT_NULL */
1013 	return simple_read_from_buffer(buf, count, ppos, mm->saved_auxv,
1014 				       nwords * sizeof(mm->saved_auxv[0]));
1015 }
1016 
1017 static const struct file_operations proc_auxv_operations = {
1018 	.open		= auxv_open,
1019 	.read		= auxv_read,
1020 	.llseek		= generic_file_llseek,
1021 	.release	= mem_release,
1022 };
1023 
1024 static ssize_t oom_adj_read(struct file *file, char __user *buf, size_t count,
1025 			    loff_t *ppos)
1026 {
1027 	struct task_struct *task = get_proc_task(file_inode(file));
1028 	char buffer[PROC_NUMBUF];
1029 	int oom_adj = OOM_ADJUST_MIN;
1030 	size_t len;
1031 
1032 	if (!task)
1033 		return -ESRCH;
1034 	if (task->signal->oom_score_adj == OOM_SCORE_ADJ_MAX)
1035 		oom_adj = OOM_ADJUST_MAX;
1036 	else
1037 		oom_adj = (task->signal->oom_score_adj * -OOM_DISABLE) /
1038 			  OOM_SCORE_ADJ_MAX;
1039 	put_task_struct(task);
1040 	len = snprintf(buffer, sizeof(buffer), "%d\n", oom_adj);
1041 	return simple_read_from_buffer(buf, count, ppos, buffer, len);
1042 }
1043 
1044 static int __set_oom_adj(struct file *file, int oom_adj, bool legacy)
1045 {
1046 	static DEFINE_MUTEX(oom_adj_mutex);
1047 	struct mm_struct *mm = NULL;
1048 	struct task_struct *task;
1049 	int err = 0;
1050 
1051 	task = get_proc_task(file_inode(file));
1052 	if (!task)
1053 		return -ESRCH;
1054 
1055 	mutex_lock(&oom_adj_mutex);
1056 	if (legacy) {
1057 		if (oom_adj < task->signal->oom_score_adj &&
1058 				!capable(CAP_SYS_RESOURCE)) {
1059 			err = -EACCES;
1060 			goto err_unlock;
1061 		}
1062 		/*
1063 		 * /proc/pid/oom_adj is provided for legacy purposes, ask users to use
1064 		 * /proc/pid/oom_score_adj instead.
1065 		 */
1066 		pr_warn_once("%s (%d): /proc/%d/oom_adj is deprecated, please use /proc/%d/oom_score_adj instead.\n",
1067 			  current->comm, task_pid_nr(current), task_pid_nr(task),
1068 			  task_pid_nr(task));
1069 	} else {
1070 		if ((short)oom_adj < task->signal->oom_score_adj_min &&
1071 				!capable(CAP_SYS_RESOURCE)) {
1072 			err = -EACCES;
1073 			goto err_unlock;
1074 		}
1075 	}
1076 
1077 	/*
1078 	 * Make sure we will check other processes sharing the mm if this is
1079 	 * not vfrok which wants its own oom_score_adj.
1080 	 * pin the mm so it doesn't go away and get reused after task_unlock
1081 	 */
1082 	if (!task->vfork_done) {
1083 		struct task_struct *p = find_lock_task_mm(task);
1084 
1085 		if (p) {
1086 			if (atomic_read(&p->mm->mm_users) > 1) {
1087 				mm = p->mm;
1088 				atomic_inc(&mm->mm_count);
1089 			}
1090 			task_unlock(p);
1091 		}
1092 	}
1093 
1094 	task->signal->oom_score_adj = oom_adj;
1095 	if (!legacy && has_capability_noaudit(current, CAP_SYS_RESOURCE))
1096 		task->signal->oom_score_adj_min = (short)oom_adj;
1097 	trace_oom_score_adj_update(task);
1098 
1099 	if (mm) {
1100 		struct task_struct *p;
1101 
1102 		rcu_read_lock();
1103 		for_each_process(p) {
1104 			if (same_thread_group(task, p))
1105 				continue;
1106 
1107 			/* do not touch kernel threads or the global init */
1108 			if (p->flags & PF_KTHREAD || is_global_init(p))
1109 				continue;
1110 
1111 			task_lock(p);
1112 			if (!p->vfork_done && process_shares_mm(p, mm)) {
1113 				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",
1114 						task_pid_nr(p), p->comm,
1115 						p->signal->oom_score_adj, oom_adj,
1116 						task_pid_nr(task), task->comm);
1117 				p->signal->oom_score_adj = oom_adj;
1118 				if (!legacy && has_capability_noaudit(current, CAP_SYS_RESOURCE))
1119 					p->signal->oom_score_adj_min = (short)oom_adj;
1120 			}
1121 			task_unlock(p);
1122 		}
1123 		rcu_read_unlock();
1124 		mmdrop(mm);
1125 	}
1126 err_unlock:
1127 	mutex_unlock(&oom_adj_mutex);
1128 	put_task_struct(task);
1129 	return err;
1130 }
1131 
1132 /*
1133  * /proc/pid/oom_adj exists solely for backwards compatibility with previous
1134  * kernels.  The effective policy is defined by oom_score_adj, which has a
1135  * different scale: oom_adj grew exponentially and oom_score_adj grows linearly.
1136  * Values written to oom_adj are simply mapped linearly to oom_score_adj.
1137  * Processes that become oom disabled via oom_adj will still be oom disabled
1138  * with this implementation.
1139  *
1140  * oom_adj cannot be removed since existing userspace binaries use it.
1141  */
1142 static ssize_t oom_adj_write(struct file *file, const char __user *buf,
1143 			     size_t count, loff_t *ppos)
1144 {
1145 	char buffer[PROC_NUMBUF];
1146 	int oom_adj;
1147 	int err;
1148 
1149 	memset(buffer, 0, sizeof(buffer));
1150 	if (count > sizeof(buffer) - 1)
1151 		count = sizeof(buffer) - 1;
1152 	if (copy_from_user(buffer, buf, count)) {
1153 		err = -EFAULT;
1154 		goto out;
1155 	}
1156 
1157 	err = kstrtoint(strstrip(buffer), 0, &oom_adj);
1158 	if (err)
1159 		goto out;
1160 	if ((oom_adj < OOM_ADJUST_MIN || oom_adj > OOM_ADJUST_MAX) &&
1161 	     oom_adj != OOM_DISABLE) {
1162 		err = -EINVAL;
1163 		goto out;
1164 	}
1165 
1166 	/*
1167 	 * Scale /proc/pid/oom_score_adj appropriately ensuring that a maximum
1168 	 * value is always attainable.
1169 	 */
1170 	if (oom_adj == OOM_ADJUST_MAX)
1171 		oom_adj = OOM_SCORE_ADJ_MAX;
1172 	else
1173 		oom_adj = (oom_adj * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE;
1174 
1175 	err = __set_oom_adj(file, oom_adj, true);
1176 out:
1177 	return err < 0 ? err : count;
1178 }
1179 
1180 static const struct file_operations proc_oom_adj_operations = {
1181 	.read		= oom_adj_read,
1182 	.write		= oom_adj_write,
1183 	.llseek		= generic_file_llseek,
1184 };
1185 
1186 static ssize_t oom_score_adj_read(struct file *file, char __user *buf,
1187 					size_t count, loff_t *ppos)
1188 {
1189 	struct task_struct *task = get_proc_task(file_inode(file));
1190 	char buffer[PROC_NUMBUF];
1191 	short oom_score_adj = OOM_SCORE_ADJ_MIN;
1192 	size_t len;
1193 
1194 	if (!task)
1195 		return -ESRCH;
1196 	oom_score_adj = task->signal->oom_score_adj;
1197 	put_task_struct(task);
1198 	len = snprintf(buffer, sizeof(buffer), "%hd\n", oom_score_adj);
1199 	return simple_read_from_buffer(buf, count, ppos, buffer, len);
1200 }
1201 
1202 static ssize_t oom_score_adj_write(struct file *file, const char __user *buf,
1203 					size_t count, loff_t *ppos)
1204 {
1205 	char buffer[PROC_NUMBUF];
1206 	int oom_score_adj;
1207 	int err;
1208 
1209 	memset(buffer, 0, sizeof(buffer));
1210 	if (count > sizeof(buffer) - 1)
1211 		count = sizeof(buffer) - 1;
1212 	if (copy_from_user(buffer, buf, count)) {
1213 		err = -EFAULT;
1214 		goto out;
1215 	}
1216 
1217 	err = kstrtoint(strstrip(buffer), 0, &oom_score_adj);
1218 	if (err)
1219 		goto out;
1220 	if (oom_score_adj < OOM_SCORE_ADJ_MIN ||
1221 			oom_score_adj > OOM_SCORE_ADJ_MAX) {
1222 		err = -EINVAL;
1223 		goto out;
1224 	}
1225 
1226 	err = __set_oom_adj(file, oom_score_adj, false);
1227 out:
1228 	return err < 0 ? err : count;
1229 }
1230 
1231 static const struct file_operations proc_oom_score_adj_operations = {
1232 	.read		= oom_score_adj_read,
1233 	.write		= oom_score_adj_write,
1234 	.llseek		= default_llseek,
1235 };
1236 
1237 #ifdef CONFIG_AUDITSYSCALL
1238 #define TMPBUFLEN 21
1239 static ssize_t proc_loginuid_read(struct file * file, char __user * buf,
1240 				  size_t count, loff_t *ppos)
1241 {
1242 	struct inode * inode = file_inode(file);
1243 	struct task_struct *task = get_proc_task(inode);
1244 	ssize_t length;
1245 	char tmpbuf[TMPBUFLEN];
1246 
1247 	if (!task)
1248 		return -ESRCH;
1249 	length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
1250 			   from_kuid(file->f_cred->user_ns,
1251 				     audit_get_loginuid(task)));
1252 	put_task_struct(task);
1253 	return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
1254 }
1255 
1256 static ssize_t proc_loginuid_write(struct file * file, const char __user * buf,
1257 				   size_t count, loff_t *ppos)
1258 {
1259 	struct inode * inode = file_inode(file);
1260 	uid_t loginuid;
1261 	kuid_t kloginuid;
1262 	int rv;
1263 
1264 	rcu_read_lock();
1265 	if (current != pid_task(proc_pid(inode), PIDTYPE_PID)) {
1266 		rcu_read_unlock();
1267 		return -EPERM;
1268 	}
1269 	rcu_read_unlock();
1270 
1271 	if (*ppos != 0) {
1272 		/* No partial writes. */
1273 		return -EINVAL;
1274 	}
1275 
1276 	rv = kstrtou32_from_user(buf, count, 10, &loginuid);
1277 	if (rv < 0)
1278 		return rv;
1279 
1280 	/* is userspace tring to explicitly UNSET the loginuid? */
1281 	if (loginuid == AUDIT_UID_UNSET) {
1282 		kloginuid = INVALID_UID;
1283 	} else {
1284 		kloginuid = make_kuid(file->f_cred->user_ns, loginuid);
1285 		if (!uid_valid(kloginuid))
1286 			return -EINVAL;
1287 	}
1288 
1289 	rv = audit_set_loginuid(kloginuid);
1290 	if (rv < 0)
1291 		return rv;
1292 	return count;
1293 }
1294 
1295 static const struct file_operations proc_loginuid_operations = {
1296 	.read		= proc_loginuid_read,
1297 	.write		= proc_loginuid_write,
1298 	.llseek		= generic_file_llseek,
1299 };
1300 
1301 static ssize_t proc_sessionid_read(struct file * file, char __user * buf,
1302 				  size_t count, loff_t *ppos)
1303 {
1304 	struct inode * inode = file_inode(file);
1305 	struct task_struct *task = get_proc_task(inode);
1306 	ssize_t length;
1307 	char tmpbuf[TMPBUFLEN];
1308 
1309 	if (!task)
1310 		return -ESRCH;
1311 	length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
1312 				audit_get_sessionid(task));
1313 	put_task_struct(task);
1314 	return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
1315 }
1316 
1317 static const struct file_operations proc_sessionid_operations = {
1318 	.read		= proc_sessionid_read,
1319 	.llseek		= generic_file_llseek,
1320 };
1321 #endif
1322 
1323 #ifdef CONFIG_FAULT_INJECTION
1324 static ssize_t proc_fault_inject_read(struct file * file, char __user * buf,
1325 				      size_t count, loff_t *ppos)
1326 {
1327 	struct task_struct *task = get_proc_task(file_inode(file));
1328 	char buffer[PROC_NUMBUF];
1329 	size_t len;
1330 	int make_it_fail;
1331 
1332 	if (!task)
1333 		return -ESRCH;
1334 	make_it_fail = task->make_it_fail;
1335 	put_task_struct(task);
1336 
1337 	len = snprintf(buffer, sizeof(buffer), "%i\n", make_it_fail);
1338 
1339 	return simple_read_from_buffer(buf, count, ppos, buffer, len);
1340 }
1341 
1342 static ssize_t proc_fault_inject_write(struct file * file,
1343 			const char __user * buf, size_t count, loff_t *ppos)
1344 {
1345 	struct task_struct *task;
1346 	char buffer[PROC_NUMBUF];
1347 	int make_it_fail;
1348 	int rv;
1349 
1350 	if (!capable(CAP_SYS_RESOURCE))
1351 		return -EPERM;
1352 	memset(buffer, 0, sizeof(buffer));
1353 	if (count > sizeof(buffer) - 1)
1354 		count = sizeof(buffer) - 1;
1355 	if (copy_from_user(buffer, buf, count))
1356 		return -EFAULT;
1357 	rv = kstrtoint(strstrip(buffer), 0, &make_it_fail);
1358 	if (rv < 0)
1359 		return rv;
1360 	if (make_it_fail < 0 || make_it_fail > 1)
1361 		return -EINVAL;
1362 
1363 	task = get_proc_task(file_inode(file));
1364 	if (!task)
1365 		return -ESRCH;
1366 	task->make_it_fail = make_it_fail;
1367 	put_task_struct(task);
1368 
1369 	return count;
1370 }
1371 
1372 static const struct file_operations proc_fault_inject_operations = {
1373 	.read		= proc_fault_inject_read,
1374 	.write		= proc_fault_inject_write,
1375 	.llseek		= generic_file_llseek,
1376 };
1377 #endif
1378 
1379 
1380 #ifdef CONFIG_SCHED_DEBUG
1381 /*
1382  * Print out various scheduling related per-task fields:
1383  */
1384 static int sched_show(struct seq_file *m, void *v)
1385 {
1386 	struct inode *inode = m->private;
1387 	struct task_struct *p;
1388 
1389 	p = get_proc_task(inode);
1390 	if (!p)
1391 		return -ESRCH;
1392 	proc_sched_show_task(p, m);
1393 
1394 	put_task_struct(p);
1395 
1396 	return 0;
1397 }
1398 
1399 static ssize_t
1400 sched_write(struct file *file, const char __user *buf,
1401 	    size_t count, loff_t *offset)
1402 {
1403 	struct inode *inode = file_inode(file);
1404 	struct task_struct *p;
1405 
1406 	p = get_proc_task(inode);
1407 	if (!p)
1408 		return -ESRCH;
1409 	proc_sched_set_task(p);
1410 
1411 	put_task_struct(p);
1412 
1413 	return count;
1414 }
1415 
1416 static int sched_open(struct inode *inode, struct file *filp)
1417 {
1418 	return single_open(filp, sched_show, inode);
1419 }
1420 
1421 static const struct file_operations proc_pid_sched_operations = {
1422 	.open		= sched_open,
1423 	.read		= seq_read,
1424 	.write		= sched_write,
1425 	.llseek		= seq_lseek,
1426 	.release	= single_release,
1427 };
1428 
1429 #endif
1430 
1431 #ifdef CONFIG_SCHED_AUTOGROUP
1432 /*
1433  * Print out autogroup related information:
1434  */
1435 static int sched_autogroup_show(struct seq_file *m, void *v)
1436 {
1437 	struct inode *inode = m->private;
1438 	struct task_struct *p;
1439 
1440 	p = get_proc_task(inode);
1441 	if (!p)
1442 		return -ESRCH;
1443 	proc_sched_autogroup_show_task(p, m);
1444 
1445 	put_task_struct(p);
1446 
1447 	return 0;
1448 }
1449 
1450 static ssize_t
1451 sched_autogroup_write(struct file *file, const char __user *buf,
1452 	    size_t count, loff_t *offset)
1453 {
1454 	struct inode *inode = file_inode(file);
1455 	struct task_struct *p;
1456 	char buffer[PROC_NUMBUF];
1457 	int nice;
1458 	int err;
1459 
1460 	memset(buffer, 0, sizeof(buffer));
1461 	if (count > sizeof(buffer) - 1)
1462 		count = sizeof(buffer) - 1;
1463 	if (copy_from_user(buffer, buf, count))
1464 		return -EFAULT;
1465 
1466 	err = kstrtoint(strstrip(buffer), 0, &nice);
1467 	if (err < 0)
1468 		return err;
1469 
1470 	p = get_proc_task(inode);
1471 	if (!p)
1472 		return -ESRCH;
1473 
1474 	err = proc_sched_autogroup_set_nice(p, nice);
1475 	if (err)
1476 		count = err;
1477 
1478 	put_task_struct(p);
1479 
1480 	return count;
1481 }
1482 
1483 static int sched_autogroup_open(struct inode *inode, struct file *filp)
1484 {
1485 	int ret;
1486 
1487 	ret = single_open(filp, sched_autogroup_show, NULL);
1488 	if (!ret) {
1489 		struct seq_file *m = filp->private_data;
1490 
1491 		m->private = inode;
1492 	}
1493 	return ret;
1494 }
1495 
1496 static const struct file_operations proc_pid_sched_autogroup_operations = {
1497 	.open		= sched_autogroup_open,
1498 	.read		= seq_read,
1499 	.write		= sched_autogroup_write,
1500 	.llseek		= seq_lseek,
1501 	.release	= single_release,
1502 };
1503 
1504 #endif /* CONFIG_SCHED_AUTOGROUP */
1505 
1506 static ssize_t comm_write(struct file *file, const char __user *buf,
1507 				size_t count, loff_t *offset)
1508 {
1509 	struct inode *inode = file_inode(file);
1510 	struct task_struct *p;
1511 	char buffer[TASK_COMM_LEN];
1512 	const size_t maxlen = sizeof(buffer) - 1;
1513 
1514 	memset(buffer, 0, sizeof(buffer));
1515 	if (copy_from_user(buffer, buf, count > maxlen ? maxlen : count))
1516 		return -EFAULT;
1517 
1518 	p = get_proc_task(inode);
1519 	if (!p)
1520 		return -ESRCH;
1521 
1522 	if (same_thread_group(current, p))
1523 		set_task_comm(p, buffer);
1524 	else
1525 		count = -EINVAL;
1526 
1527 	put_task_struct(p);
1528 
1529 	return count;
1530 }
1531 
1532 static int comm_show(struct seq_file *m, void *v)
1533 {
1534 	struct inode *inode = m->private;
1535 	struct task_struct *p;
1536 
1537 	p = get_proc_task(inode);
1538 	if (!p)
1539 		return -ESRCH;
1540 
1541 	task_lock(p);
1542 	seq_printf(m, "%s\n", p->comm);
1543 	task_unlock(p);
1544 
1545 	put_task_struct(p);
1546 
1547 	return 0;
1548 }
1549 
1550 static int comm_open(struct inode *inode, struct file *filp)
1551 {
1552 	return single_open(filp, comm_show, inode);
1553 }
1554 
1555 static const struct file_operations proc_pid_set_comm_operations = {
1556 	.open		= comm_open,
1557 	.read		= seq_read,
1558 	.write		= comm_write,
1559 	.llseek		= seq_lseek,
1560 	.release	= single_release,
1561 };
1562 
1563 static int proc_exe_link(struct dentry *dentry, struct path *exe_path)
1564 {
1565 	struct task_struct *task;
1566 	struct file *exe_file;
1567 
1568 	task = get_proc_task(d_inode(dentry));
1569 	if (!task)
1570 		return -ENOENT;
1571 	exe_file = get_task_exe_file(task);
1572 	put_task_struct(task);
1573 	if (exe_file) {
1574 		*exe_path = exe_file->f_path;
1575 		path_get(&exe_file->f_path);
1576 		fput(exe_file);
1577 		return 0;
1578 	} else
1579 		return -ENOENT;
1580 }
1581 
1582 static const char *proc_pid_get_link(struct dentry *dentry,
1583 				     struct inode *inode,
1584 				     struct delayed_call *done)
1585 {
1586 	struct path path;
1587 	int error = -EACCES;
1588 
1589 	if (!dentry)
1590 		return ERR_PTR(-ECHILD);
1591 
1592 	/* Are we allowed to snoop on the tasks file descriptors? */
1593 	if (!proc_fd_access_allowed(inode))
1594 		goto out;
1595 
1596 	error = PROC_I(inode)->op.proc_get_link(dentry, &path);
1597 	if (error)
1598 		goto out;
1599 
1600 	nd_jump_link(&path);
1601 	return NULL;
1602 out:
1603 	return ERR_PTR(error);
1604 }
1605 
1606 static int do_proc_readlink(struct path *path, char __user *buffer, int buflen)
1607 {
1608 	char *tmp = (char*)__get_free_page(GFP_TEMPORARY);
1609 	char *pathname;
1610 	int len;
1611 
1612 	if (!tmp)
1613 		return -ENOMEM;
1614 
1615 	pathname = d_path(path, tmp, PAGE_SIZE);
1616 	len = PTR_ERR(pathname);
1617 	if (IS_ERR(pathname))
1618 		goto out;
1619 	len = tmp + PAGE_SIZE - 1 - pathname;
1620 
1621 	if (len > buflen)
1622 		len = buflen;
1623 	if (copy_to_user(buffer, pathname, len))
1624 		len = -EFAULT;
1625  out:
1626 	free_page((unsigned long)tmp);
1627 	return len;
1628 }
1629 
1630 static int proc_pid_readlink(struct dentry * dentry, char __user * buffer, int buflen)
1631 {
1632 	int error = -EACCES;
1633 	struct inode *inode = d_inode(dentry);
1634 	struct path path;
1635 
1636 	/* Are we allowed to snoop on the tasks file descriptors? */
1637 	if (!proc_fd_access_allowed(inode))
1638 		goto out;
1639 
1640 	error = PROC_I(inode)->op.proc_get_link(dentry, &path);
1641 	if (error)
1642 		goto out;
1643 
1644 	error = do_proc_readlink(&path, buffer, buflen);
1645 	path_put(&path);
1646 out:
1647 	return error;
1648 }
1649 
1650 const struct inode_operations proc_pid_link_inode_operations = {
1651 	.readlink	= proc_pid_readlink,
1652 	.get_link	= proc_pid_get_link,
1653 	.setattr	= proc_setattr,
1654 };
1655 
1656 
1657 /* building an inode */
1658 
1659 struct inode *proc_pid_make_inode(struct super_block * sb, struct task_struct *task)
1660 {
1661 	struct inode * inode;
1662 	struct proc_inode *ei;
1663 	const struct cred *cred;
1664 
1665 	/* We need a new inode */
1666 
1667 	inode = new_inode(sb);
1668 	if (!inode)
1669 		goto out;
1670 
1671 	/* Common stuff */
1672 	ei = PROC_I(inode);
1673 	inode->i_ino = get_next_ino();
1674 	inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
1675 	inode->i_op = &proc_def_inode_operations;
1676 
1677 	/*
1678 	 * grab the reference to task.
1679 	 */
1680 	ei->pid = get_task_pid(task, PIDTYPE_PID);
1681 	if (!ei->pid)
1682 		goto out_unlock;
1683 
1684 	if (task_dumpable(task)) {
1685 		rcu_read_lock();
1686 		cred = __task_cred(task);
1687 		inode->i_uid = cred->euid;
1688 		inode->i_gid = cred->egid;
1689 		rcu_read_unlock();
1690 	}
1691 	security_task_to_inode(task, inode);
1692 
1693 out:
1694 	return inode;
1695 
1696 out_unlock:
1697 	iput(inode);
1698 	return NULL;
1699 }
1700 
1701 int pid_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
1702 {
1703 	struct inode *inode = d_inode(dentry);
1704 	struct task_struct *task;
1705 	const struct cred *cred;
1706 	struct pid_namespace *pid = dentry->d_sb->s_fs_info;
1707 
1708 	generic_fillattr(inode, stat);
1709 
1710 	rcu_read_lock();
1711 	stat->uid = GLOBAL_ROOT_UID;
1712 	stat->gid = GLOBAL_ROOT_GID;
1713 	task = pid_task(proc_pid(inode), PIDTYPE_PID);
1714 	if (task) {
1715 		if (!has_pid_permissions(pid, task, 2)) {
1716 			rcu_read_unlock();
1717 			/*
1718 			 * This doesn't prevent learning whether PID exists,
1719 			 * it only makes getattr() consistent with readdir().
1720 			 */
1721 			return -ENOENT;
1722 		}
1723 		if ((inode->i_mode == (S_IFDIR|S_IRUGO|S_IXUGO)) ||
1724 		    task_dumpable(task)) {
1725 			cred = __task_cred(task);
1726 			stat->uid = cred->euid;
1727 			stat->gid = cred->egid;
1728 		}
1729 	}
1730 	rcu_read_unlock();
1731 	return 0;
1732 }
1733 
1734 /* dentry stuff */
1735 
1736 /*
1737  *	Exceptional case: normally we are not allowed to unhash a busy
1738  * directory. In this case, however, we can do it - no aliasing problems
1739  * due to the way we treat inodes.
1740  *
1741  * Rewrite the inode's ownerships here because the owning task may have
1742  * performed a setuid(), etc.
1743  *
1744  * Before the /proc/pid/status file was created the only way to read
1745  * the effective uid of a /process was to stat /proc/pid.  Reading
1746  * /proc/pid/status is slow enough that procps and other packages
1747  * kept stating /proc/pid.  To keep the rules in /proc simple I have
1748  * made this apply to all per process world readable and executable
1749  * directories.
1750  */
1751 int pid_revalidate(struct dentry *dentry, unsigned int flags)
1752 {
1753 	struct inode *inode;
1754 	struct task_struct *task;
1755 	const struct cred *cred;
1756 
1757 	if (flags & LOOKUP_RCU)
1758 		return -ECHILD;
1759 
1760 	inode = d_inode(dentry);
1761 	task = get_proc_task(inode);
1762 
1763 	if (task) {
1764 		if ((inode->i_mode == (S_IFDIR|S_IRUGO|S_IXUGO)) ||
1765 		    task_dumpable(task)) {
1766 			rcu_read_lock();
1767 			cred = __task_cred(task);
1768 			inode->i_uid = cred->euid;
1769 			inode->i_gid = cred->egid;
1770 			rcu_read_unlock();
1771 		} else {
1772 			inode->i_uid = GLOBAL_ROOT_UID;
1773 			inode->i_gid = GLOBAL_ROOT_GID;
1774 		}
1775 		inode->i_mode &= ~(S_ISUID | S_ISGID);
1776 		security_task_to_inode(task, inode);
1777 		put_task_struct(task);
1778 		return 1;
1779 	}
1780 	return 0;
1781 }
1782 
1783 static inline bool proc_inode_is_dead(struct inode *inode)
1784 {
1785 	return !proc_pid(inode)->tasks[PIDTYPE_PID].first;
1786 }
1787 
1788 int pid_delete_dentry(const struct dentry *dentry)
1789 {
1790 	/* Is the task we represent dead?
1791 	 * If so, then don't put the dentry on the lru list,
1792 	 * kill it immediately.
1793 	 */
1794 	return proc_inode_is_dead(d_inode(dentry));
1795 }
1796 
1797 const struct dentry_operations pid_dentry_operations =
1798 {
1799 	.d_revalidate	= pid_revalidate,
1800 	.d_delete	= pid_delete_dentry,
1801 };
1802 
1803 /* Lookups */
1804 
1805 /*
1806  * Fill a directory entry.
1807  *
1808  * If possible create the dcache entry and derive our inode number and
1809  * file type from dcache entry.
1810  *
1811  * Since all of the proc inode numbers are dynamically generated, the inode
1812  * numbers do not exist until the inode is cache.  This means creating the
1813  * the dcache entry in readdir is necessary to keep the inode numbers
1814  * reported by readdir in sync with the inode numbers reported
1815  * by stat.
1816  */
1817 bool proc_fill_cache(struct file *file, struct dir_context *ctx,
1818 	const char *name, int len,
1819 	instantiate_t instantiate, struct task_struct *task, const void *ptr)
1820 {
1821 	struct dentry *child, *dir = file->f_path.dentry;
1822 	struct qstr qname = QSTR_INIT(name, len);
1823 	struct inode *inode;
1824 	unsigned type;
1825 	ino_t ino;
1826 
1827 	child = d_hash_and_lookup(dir, &qname);
1828 	if (!child) {
1829 		DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
1830 		child = d_alloc_parallel(dir, &qname, &wq);
1831 		if (IS_ERR(child))
1832 			goto end_instantiate;
1833 		if (d_in_lookup(child)) {
1834 			int err = instantiate(d_inode(dir), child, task, ptr);
1835 			d_lookup_done(child);
1836 			if (err < 0) {
1837 				dput(child);
1838 				goto end_instantiate;
1839 			}
1840 		}
1841 	}
1842 	inode = d_inode(child);
1843 	ino = inode->i_ino;
1844 	type = inode->i_mode >> 12;
1845 	dput(child);
1846 	return dir_emit(ctx, name, len, ino, type);
1847 
1848 end_instantiate:
1849 	return dir_emit(ctx, name, len, 1, DT_UNKNOWN);
1850 }
1851 
1852 /*
1853  * dname_to_vma_addr - maps a dentry name into two unsigned longs
1854  * which represent vma start and end addresses.
1855  */
1856 static int dname_to_vma_addr(struct dentry *dentry,
1857 			     unsigned long *start, unsigned long *end)
1858 {
1859 	if (sscanf(dentry->d_name.name, "%lx-%lx", start, end) != 2)
1860 		return -EINVAL;
1861 
1862 	return 0;
1863 }
1864 
1865 static int map_files_d_revalidate(struct dentry *dentry, unsigned int flags)
1866 {
1867 	unsigned long vm_start, vm_end;
1868 	bool exact_vma_exists = false;
1869 	struct mm_struct *mm = NULL;
1870 	struct task_struct *task;
1871 	const struct cred *cred;
1872 	struct inode *inode;
1873 	int status = 0;
1874 
1875 	if (flags & LOOKUP_RCU)
1876 		return -ECHILD;
1877 
1878 	inode = d_inode(dentry);
1879 	task = get_proc_task(inode);
1880 	if (!task)
1881 		goto out_notask;
1882 
1883 	mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
1884 	if (IS_ERR_OR_NULL(mm))
1885 		goto out;
1886 
1887 	if (!dname_to_vma_addr(dentry, &vm_start, &vm_end)) {
1888 		down_read(&mm->mmap_sem);
1889 		exact_vma_exists = !!find_exact_vma(mm, vm_start, vm_end);
1890 		up_read(&mm->mmap_sem);
1891 	}
1892 
1893 	mmput(mm);
1894 
1895 	if (exact_vma_exists) {
1896 		if (task_dumpable(task)) {
1897 			rcu_read_lock();
1898 			cred = __task_cred(task);
1899 			inode->i_uid = cred->euid;
1900 			inode->i_gid = cred->egid;
1901 			rcu_read_unlock();
1902 		} else {
1903 			inode->i_uid = GLOBAL_ROOT_UID;
1904 			inode->i_gid = GLOBAL_ROOT_GID;
1905 		}
1906 		security_task_to_inode(task, inode);
1907 		status = 1;
1908 	}
1909 
1910 out:
1911 	put_task_struct(task);
1912 
1913 out_notask:
1914 	return status;
1915 }
1916 
1917 static const struct dentry_operations tid_map_files_dentry_operations = {
1918 	.d_revalidate	= map_files_d_revalidate,
1919 	.d_delete	= pid_delete_dentry,
1920 };
1921 
1922 static int map_files_get_link(struct dentry *dentry, struct path *path)
1923 {
1924 	unsigned long vm_start, vm_end;
1925 	struct vm_area_struct *vma;
1926 	struct task_struct *task;
1927 	struct mm_struct *mm;
1928 	int rc;
1929 
1930 	rc = -ENOENT;
1931 	task = get_proc_task(d_inode(dentry));
1932 	if (!task)
1933 		goto out;
1934 
1935 	mm = get_task_mm(task);
1936 	put_task_struct(task);
1937 	if (!mm)
1938 		goto out;
1939 
1940 	rc = dname_to_vma_addr(dentry, &vm_start, &vm_end);
1941 	if (rc)
1942 		goto out_mmput;
1943 
1944 	rc = -ENOENT;
1945 	down_read(&mm->mmap_sem);
1946 	vma = find_exact_vma(mm, vm_start, vm_end);
1947 	if (vma && vma->vm_file) {
1948 		*path = vma->vm_file->f_path;
1949 		path_get(path);
1950 		rc = 0;
1951 	}
1952 	up_read(&mm->mmap_sem);
1953 
1954 out_mmput:
1955 	mmput(mm);
1956 out:
1957 	return rc;
1958 }
1959 
1960 struct map_files_info {
1961 	fmode_t		mode;
1962 	unsigned long	len;
1963 	unsigned char	name[4*sizeof(long)+2]; /* max: %lx-%lx\0 */
1964 };
1965 
1966 /*
1967  * Only allow CAP_SYS_ADMIN to follow the links, due to concerns about how the
1968  * symlinks may be used to bypass permissions on ancestor directories in the
1969  * path to the file in question.
1970  */
1971 static const char *
1972 proc_map_files_get_link(struct dentry *dentry,
1973 			struct inode *inode,
1974 		        struct delayed_call *done)
1975 {
1976 	if (!capable(CAP_SYS_ADMIN))
1977 		return ERR_PTR(-EPERM);
1978 
1979 	return proc_pid_get_link(dentry, inode, done);
1980 }
1981 
1982 /*
1983  * Identical to proc_pid_link_inode_operations except for get_link()
1984  */
1985 static const struct inode_operations proc_map_files_link_inode_operations = {
1986 	.readlink	= proc_pid_readlink,
1987 	.get_link	= proc_map_files_get_link,
1988 	.setattr	= proc_setattr,
1989 };
1990 
1991 static int
1992 proc_map_files_instantiate(struct inode *dir, struct dentry *dentry,
1993 			   struct task_struct *task, const void *ptr)
1994 {
1995 	fmode_t mode = (fmode_t)(unsigned long)ptr;
1996 	struct proc_inode *ei;
1997 	struct inode *inode;
1998 
1999 	inode = proc_pid_make_inode(dir->i_sb, task);
2000 	if (!inode)
2001 		return -ENOENT;
2002 
2003 	ei = PROC_I(inode);
2004 	ei->op.proc_get_link = map_files_get_link;
2005 
2006 	inode->i_op = &proc_map_files_link_inode_operations;
2007 	inode->i_size = 64;
2008 	inode->i_mode = S_IFLNK;
2009 
2010 	if (mode & FMODE_READ)
2011 		inode->i_mode |= S_IRUSR;
2012 	if (mode & FMODE_WRITE)
2013 		inode->i_mode |= S_IWUSR;
2014 
2015 	d_set_d_op(dentry, &tid_map_files_dentry_operations);
2016 	d_add(dentry, inode);
2017 
2018 	return 0;
2019 }
2020 
2021 static struct dentry *proc_map_files_lookup(struct inode *dir,
2022 		struct dentry *dentry, unsigned int flags)
2023 {
2024 	unsigned long vm_start, vm_end;
2025 	struct vm_area_struct *vma;
2026 	struct task_struct *task;
2027 	int result;
2028 	struct mm_struct *mm;
2029 
2030 	result = -ENOENT;
2031 	task = get_proc_task(dir);
2032 	if (!task)
2033 		goto out;
2034 
2035 	result = -EACCES;
2036 	if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
2037 		goto out_put_task;
2038 
2039 	result = -ENOENT;
2040 	if (dname_to_vma_addr(dentry, &vm_start, &vm_end))
2041 		goto out_put_task;
2042 
2043 	mm = get_task_mm(task);
2044 	if (!mm)
2045 		goto out_put_task;
2046 
2047 	down_read(&mm->mmap_sem);
2048 	vma = find_exact_vma(mm, vm_start, vm_end);
2049 	if (!vma)
2050 		goto out_no_vma;
2051 
2052 	if (vma->vm_file)
2053 		result = proc_map_files_instantiate(dir, dentry, task,
2054 				(void *)(unsigned long)vma->vm_file->f_mode);
2055 
2056 out_no_vma:
2057 	up_read(&mm->mmap_sem);
2058 	mmput(mm);
2059 out_put_task:
2060 	put_task_struct(task);
2061 out:
2062 	return ERR_PTR(result);
2063 }
2064 
2065 static const struct inode_operations proc_map_files_inode_operations = {
2066 	.lookup		= proc_map_files_lookup,
2067 	.permission	= proc_fd_permission,
2068 	.setattr	= proc_setattr,
2069 };
2070 
2071 static int
2072 proc_map_files_readdir(struct file *file, struct dir_context *ctx)
2073 {
2074 	struct vm_area_struct *vma;
2075 	struct task_struct *task;
2076 	struct mm_struct *mm;
2077 	unsigned long nr_files, pos, i;
2078 	struct flex_array *fa = NULL;
2079 	struct map_files_info info;
2080 	struct map_files_info *p;
2081 	int ret;
2082 
2083 	ret = -ENOENT;
2084 	task = get_proc_task(file_inode(file));
2085 	if (!task)
2086 		goto out;
2087 
2088 	ret = -EACCES;
2089 	if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
2090 		goto out_put_task;
2091 
2092 	ret = 0;
2093 	if (!dir_emit_dots(file, ctx))
2094 		goto out_put_task;
2095 
2096 	mm = get_task_mm(task);
2097 	if (!mm)
2098 		goto out_put_task;
2099 	down_read(&mm->mmap_sem);
2100 
2101 	nr_files = 0;
2102 
2103 	/*
2104 	 * We need two passes here:
2105 	 *
2106 	 *  1) Collect vmas of mapped files with mmap_sem taken
2107 	 *  2) Release mmap_sem and instantiate entries
2108 	 *
2109 	 * otherwise we get lockdep complained, since filldir()
2110 	 * routine might require mmap_sem taken in might_fault().
2111 	 */
2112 
2113 	for (vma = mm->mmap, pos = 2; vma; vma = vma->vm_next) {
2114 		if (vma->vm_file && ++pos > ctx->pos)
2115 			nr_files++;
2116 	}
2117 
2118 	if (nr_files) {
2119 		fa = flex_array_alloc(sizeof(info), nr_files,
2120 					GFP_KERNEL);
2121 		if (!fa || flex_array_prealloc(fa, 0, nr_files,
2122 						GFP_KERNEL)) {
2123 			ret = -ENOMEM;
2124 			if (fa)
2125 				flex_array_free(fa);
2126 			up_read(&mm->mmap_sem);
2127 			mmput(mm);
2128 			goto out_put_task;
2129 		}
2130 		for (i = 0, vma = mm->mmap, pos = 2; vma;
2131 				vma = vma->vm_next) {
2132 			if (!vma->vm_file)
2133 				continue;
2134 			if (++pos <= ctx->pos)
2135 				continue;
2136 
2137 			info.mode = vma->vm_file->f_mode;
2138 			info.len = snprintf(info.name,
2139 					sizeof(info.name), "%lx-%lx",
2140 					vma->vm_start, vma->vm_end);
2141 			if (flex_array_put(fa, i++, &info, GFP_KERNEL))
2142 				BUG();
2143 		}
2144 	}
2145 	up_read(&mm->mmap_sem);
2146 
2147 	for (i = 0; i < nr_files; i++) {
2148 		p = flex_array_get(fa, i);
2149 		if (!proc_fill_cache(file, ctx,
2150 				      p->name, p->len,
2151 				      proc_map_files_instantiate,
2152 				      task,
2153 				      (void *)(unsigned long)p->mode))
2154 			break;
2155 		ctx->pos++;
2156 	}
2157 	if (fa)
2158 		flex_array_free(fa);
2159 	mmput(mm);
2160 
2161 out_put_task:
2162 	put_task_struct(task);
2163 out:
2164 	return ret;
2165 }
2166 
2167 static const struct file_operations proc_map_files_operations = {
2168 	.read		= generic_read_dir,
2169 	.iterate_shared	= proc_map_files_readdir,
2170 	.llseek		= generic_file_llseek,
2171 };
2172 
2173 #ifdef CONFIG_CHECKPOINT_RESTORE
2174 struct timers_private {
2175 	struct pid *pid;
2176 	struct task_struct *task;
2177 	struct sighand_struct *sighand;
2178 	struct pid_namespace *ns;
2179 	unsigned long flags;
2180 };
2181 
2182 static void *timers_start(struct seq_file *m, loff_t *pos)
2183 {
2184 	struct timers_private *tp = m->private;
2185 
2186 	tp->task = get_pid_task(tp->pid, PIDTYPE_PID);
2187 	if (!tp->task)
2188 		return ERR_PTR(-ESRCH);
2189 
2190 	tp->sighand = lock_task_sighand(tp->task, &tp->flags);
2191 	if (!tp->sighand)
2192 		return ERR_PTR(-ESRCH);
2193 
2194 	return seq_list_start(&tp->task->signal->posix_timers, *pos);
2195 }
2196 
2197 static void *timers_next(struct seq_file *m, void *v, loff_t *pos)
2198 {
2199 	struct timers_private *tp = m->private;
2200 	return seq_list_next(v, &tp->task->signal->posix_timers, pos);
2201 }
2202 
2203 static void timers_stop(struct seq_file *m, void *v)
2204 {
2205 	struct timers_private *tp = m->private;
2206 
2207 	if (tp->sighand) {
2208 		unlock_task_sighand(tp->task, &tp->flags);
2209 		tp->sighand = NULL;
2210 	}
2211 
2212 	if (tp->task) {
2213 		put_task_struct(tp->task);
2214 		tp->task = NULL;
2215 	}
2216 }
2217 
2218 static int show_timer(struct seq_file *m, void *v)
2219 {
2220 	struct k_itimer *timer;
2221 	struct timers_private *tp = m->private;
2222 	int notify;
2223 	static const char * const nstr[] = {
2224 		[SIGEV_SIGNAL] = "signal",
2225 		[SIGEV_NONE] = "none",
2226 		[SIGEV_THREAD] = "thread",
2227 	};
2228 
2229 	timer = list_entry((struct list_head *)v, struct k_itimer, list);
2230 	notify = timer->it_sigev_notify;
2231 
2232 	seq_printf(m, "ID: %d\n", timer->it_id);
2233 	seq_printf(m, "signal: %d/%p\n",
2234 		   timer->sigq->info.si_signo,
2235 		   timer->sigq->info.si_value.sival_ptr);
2236 	seq_printf(m, "notify: %s/%s.%d\n",
2237 		   nstr[notify & ~SIGEV_THREAD_ID],
2238 		   (notify & SIGEV_THREAD_ID) ? "tid" : "pid",
2239 		   pid_nr_ns(timer->it_pid, tp->ns));
2240 	seq_printf(m, "ClockID: %d\n", timer->it_clock);
2241 
2242 	return 0;
2243 }
2244 
2245 static const struct seq_operations proc_timers_seq_ops = {
2246 	.start	= timers_start,
2247 	.next	= timers_next,
2248 	.stop	= timers_stop,
2249 	.show	= show_timer,
2250 };
2251 
2252 static int proc_timers_open(struct inode *inode, struct file *file)
2253 {
2254 	struct timers_private *tp;
2255 
2256 	tp = __seq_open_private(file, &proc_timers_seq_ops,
2257 			sizeof(struct timers_private));
2258 	if (!tp)
2259 		return -ENOMEM;
2260 
2261 	tp->pid = proc_pid(inode);
2262 	tp->ns = inode->i_sb->s_fs_info;
2263 	return 0;
2264 }
2265 
2266 static const struct file_operations proc_timers_operations = {
2267 	.open		= proc_timers_open,
2268 	.read		= seq_read,
2269 	.llseek		= seq_lseek,
2270 	.release	= seq_release_private,
2271 };
2272 #endif
2273 
2274 static ssize_t timerslack_ns_write(struct file *file, const char __user *buf,
2275 					size_t count, loff_t *offset)
2276 {
2277 	struct inode *inode = file_inode(file);
2278 	struct task_struct *p;
2279 	u64 slack_ns;
2280 	int err;
2281 
2282 	err = kstrtoull_from_user(buf, count, 10, &slack_ns);
2283 	if (err < 0)
2284 		return err;
2285 
2286 	p = get_proc_task(inode);
2287 	if (!p)
2288 		return -ESRCH;
2289 
2290 	if (p != current) {
2291 		if (!capable(CAP_SYS_NICE)) {
2292 			count = -EPERM;
2293 			goto out;
2294 		}
2295 
2296 		err = security_task_setscheduler(p);
2297 		if (err) {
2298 			count = err;
2299 			goto out;
2300 		}
2301 	}
2302 
2303 	task_lock(p);
2304 	if (slack_ns == 0)
2305 		p->timer_slack_ns = p->default_timer_slack_ns;
2306 	else
2307 		p->timer_slack_ns = slack_ns;
2308 	task_unlock(p);
2309 
2310 out:
2311 	put_task_struct(p);
2312 
2313 	return count;
2314 }
2315 
2316 static int timerslack_ns_show(struct seq_file *m, void *v)
2317 {
2318 	struct inode *inode = m->private;
2319 	struct task_struct *p;
2320 	int err = 0;
2321 
2322 	p = get_proc_task(inode);
2323 	if (!p)
2324 		return -ESRCH;
2325 
2326 	if (p != current) {
2327 
2328 		if (!capable(CAP_SYS_NICE)) {
2329 			err = -EPERM;
2330 			goto out;
2331 		}
2332 		err = security_task_getscheduler(p);
2333 		if (err)
2334 			goto out;
2335 	}
2336 
2337 	task_lock(p);
2338 	seq_printf(m, "%llu\n", p->timer_slack_ns);
2339 	task_unlock(p);
2340 
2341 out:
2342 	put_task_struct(p);
2343 
2344 	return err;
2345 }
2346 
2347 static int timerslack_ns_open(struct inode *inode, struct file *filp)
2348 {
2349 	return single_open(filp, timerslack_ns_show, inode);
2350 }
2351 
2352 static const struct file_operations proc_pid_set_timerslack_ns_operations = {
2353 	.open		= timerslack_ns_open,
2354 	.read		= seq_read,
2355 	.write		= timerslack_ns_write,
2356 	.llseek		= seq_lseek,
2357 	.release	= single_release,
2358 };
2359 
2360 static int proc_pident_instantiate(struct inode *dir,
2361 	struct dentry *dentry, struct task_struct *task, const void *ptr)
2362 {
2363 	const struct pid_entry *p = ptr;
2364 	struct inode *inode;
2365 	struct proc_inode *ei;
2366 
2367 	inode = proc_pid_make_inode(dir->i_sb, task);
2368 	if (!inode)
2369 		goto out;
2370 
2371 	ei = PROC_I(inode);
2372 	inode->i_mode = p->mode;
2373 	if (S_ISDIR(inode->i_mode))
2374 		set_nlink(inode, 2);	/* Use getattr to fix if necessary */
2375 	if (p->iop)
2376 		inode->i_op = p->iop;
2377 	if (p->fop)
2378 		inode->i_fop = p->fop;
2379 	ei->op = p->op;
2380 	d_set_d_op(dentry, &pid_dentry_operations);
2381 	d_add(dentry, inode);
2382 	/* Close the race of the process dying before we return the dentry */
2383 	if (pid_revalidate(dentry, 0))
2384 		return 0;
2385 out:
2386 	return -ENOENT;
2387 }
2388 
2389 static struct dentry *proc_pident_lookup(struct inode *dir,
2390 					 struct dentry *dentry,
2391 					 const struct pid_entry *ents,
2392 					 unsigned int nents)
2393 {
2394 	int error;
2395 	struct task_struct *task = get_proc_task(dir);
2396 	const struct pid_entry *p, *last;
2397 
2398 	error = -ENOENT;
2399 
2400 	if (!task)
2401 		goto out_no_task;
2402 
2403 	/*
2404 	 * Yes, it does not scale. And it should not. Don't add
2405 	 * new entries into /proc/<tgid>/ without very good reasons.
2406 	 */
2407 	last = &ents[nents - 1];
2408 	for (p = ents; p <= last; p++) {
2409 		if (p->len != dentry->d_name.len)
2410 			continue;
2411 		if (!memcmp(dentry->d_name.name, p->name, p->len))
2412 			break;
2413 	}
2414 	if (p > last)
2415 		goto out;
2416 
2417 	error = proc_pident_instantiate(dir, dentry, task, p);
2418 out:
2419 	put_task_struct(task);
2420 out_no_task:
2421 	return ERR_PTR(error);
2422 }
2423 
2424 static int proc_pident_readdir(struct file *file, struct dir_context *ctx,
2425 		const struct pid_entry *ents, unsigned int nents)
2426 {
2427 	struct task_struct *task = get_proc_task(file_inode(file));
2428 	const struct pid_entry *p;
2429 
2430 	if (!task)
2431 		return -ENOENT;
2432 
2433 	if (!dir_emit_dots(file, ctx))
2434 		goto out;
2435 
2436 	if (ctx->pos >= nents + 2)
2437 		goto out;
2438 
2439 	for (p = ents + (ctx->pos - 2); p <= ents + nents - 1; p++) {
2440 		if (!proc_fill_cache(file, ctx, p->name, p->len,
2441 				proc_pident_instantiate, task, p))
2442 			break;
2443 		ctx->pos++;
2444 	}
2445 out:
2446 	put_task_struct(task);
2447 	return 0;
2448 }
2449 
2450 #ifdef CONFIG_SECURITY
2451 static ssize_t proc_pid_attr_read(struct file * file, char __user * buf,
2452 				  size_t count, loff_t *ppos)
2453 {
2454 	struct inode * inode = file_inode(file);
2455 	char *p = NULL;
2456 	ssize_t length;
2457 	struct task_struct *task = get_proc_task(inode);
2458 
2459 	if (!task)
2460 		return -ESRCH;
2461 
2462 	length = security_getprocattr(task,
2463 				      (char*)file->f_path.dentry->d_name.name,
2464 				      &p);
2465 	put_task_struct(task);
2466 	if (length > 0)
2467 		length = simple_read_from_buffer(buf, count, ppos, p, length);
2468 	kfree(p);
2469 	return length;
2470 }
2471 
2472 static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
2473 				   size_t count, loff_t *ppos)
2474 {
2475 	struct inode * inode = file_inode(file);
2476 	void *page;
2477 	ssize_t length;
2478 	struct task_struct *task = get_proc_task(inode);
2479 
2480 	length = -ESRCH;
2481 	if (!task)
2482 		goto out_no_task;
2483 	if (count > PAGE_SIZE)
2484 		count = PAGE_SIZE;
2485 
2486 	/* No partial writes. */
2487 	length = -EINVAL;
2488 	if (*ppos != 0)
2489 		goto out;
2490 
2491 	page = memdup_user(buf, count);
2492 	if (IS_ERR(page)) {
2493 		length = PTR_ERR(page);
2494 		goto out;
2495 	}
2496 
2497 	/* Guard against adverse ptrace interaction */
2498 	length = mutex_lock_interruptible(&task->signal->cred_guard_mutex);
2499 	if (length < 0)
2500 		goto out_free;
2501 
2502 	length = security_setprocattr(task,
2503 				      (char*)file->f_path.dentry->d_name.name,
2504 				      page, count);
2505 	mutex_unlock(&task->signal->cred_guard_mutex);
2506 out_free:
2507 	kfree(page);
2508 out:
2509 	put_task_struct(task);
2510 out_no_task:
2511 	return length;
2512 }
2513 
2514 static const struct file_operations proc_pid_attr_operations = {
2515 	.read		= proc_pid_attr_read,
2516 	.write		= proc_pid_attr_write,
2517 	.llseek		= generic_file_llseek,
2518 };
2519 
2520 static const struct pid_entry attr_dir_stuff[] = {
2521 	REG("current",    S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2522 	REG("prev",       S_IRUGO,	   proc_pid_attr_operations),
2523 	REG("exec",       S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2524 	REG("fscreate",   S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2525 	REG("keycreate",  S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2526 	REG("sockcreate", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2527 };
2528 
2529 static int proc_attr_dir_readdir(struct file *file, struct dir_context *ctx)
2530 {
2531 	return proc_pident_readdir(file, ctx,
2532 				   attr_dir_stuff, ARRAY_SIZE(attr_dir_stuff));
2533 }
2534 
2535 static const struct file_operations proc_attr_dir_operations = {
2536 	.read		= generic_read_dir,
2537 	.iterate_shared	= proc_attr_dir_readdir,
2538 	.llseek		= generic_file_llseek,
2539 };
2540 
2541 static struct dentry *proc_attr_dir_lookup(struct inode *dir,
2542 				struct dentry *dentry, unsigned int flags)
2543 {
2544 	return proc_pident_lookup(dir, dentry,
2545 				  attr_dir_stuff, ARRAY_SIZE(attr_dir_stuff));
2546 }
2547 
2548 static const struct inode_operations proc_attr_dir_inode_operations = {
2549 	.lookup		= proc_attr_dir_lookup,
2550 	.getattr	= pid_getattr,
2551 	.setattr	= proc_setattr,
2552 };
2553 
2554 #endif
2555 
2556 #ifdef CONFIG_ELF_CORE
2557 static ssize_t proc_coredump_filter_read(struct file *file, char __user *buf,
2558 					 size_t count, loff_t *ppos)
2559 {
2560 	struct task_struct *task = get_proc_task(file_inode(file));
2561 	struct mm_struct *mm;
2562 	char buffer[PROC_NUMBUF];
2563 	size_t len;
2564 	int ret;
2565 
2566 	if (!task)
2567 		return -ESRCH;
2568 
2569 	ret = 0;
2570 	mm = get_task_mm(task);
2571 	if (mm) {
2572 		len = snprintf(buffer, sizeof(buffer), "%08lx\n",
2573 			       ((mm->flags & MMF_DUMP_FILTER_MASK) >>
2574 				MMF_DUMP_FILTER_SHIFT));
2575 		mmput(mm);
2576 		ret = simple_read_from_buffer(buf, count, ppos, buffer, len);
2577 	}
2578 
2579 	put_task_struct(task);
2580 
2581 	return ret;
2582 }
2583 
2584 static ssize_t proc_coredump_filter_write(struct file *file,
2585 					  const char __user *buf,
2586 					  size_t count,
2587 					  loff_t *ppos)
2588 {
2589 	struct task_struct *task;
2590 	struct mm_struct *mm;
2591 	unsigned int val;
2592 	int ret;
2593 	int i;
2594 	unsigned long mask;
2595 
2596 	ret = kstrtouint_from_user(buf, count, 0, &val);
2597 	if (ret < 0)
2598 		return ret;
2599 
2600 	ret = -ESRCH;
2601 	task = get_proc_task(file_inode(file));
2602 	if (!task)
2603 		goto out_no_task;
2604 
2605 	mm = get_task_mm(task);
2606 	if (!mm)
2607 		goto out_no_mm;
2608 	ret = 0;
2609 
2610 	for (i = 0, mask = 1; i < MMF_DUMP_FILTER_BITS; i++, mask <<= 1) {
2611 		if (val & mask)
2612 			set_bit(i + MMF_DUMP_FILTER_SHIFT, &mm->flags);
2613 		else
2614 			clear_bit(i + MMF_DUMP_FILTER_SHIFT, &mm->flags);
2615 	}
2616 
2617 	mmput(mm);
2618  out_no_mm:
2619 	put_task_struct(task);
2620  out_no_task:
2621 	if (ret < 0)
2622 		return ret;
2623 	return count;
2624 }
2625 
2626 static const struct file_operations proc_coredump_filter_operations = {
2627 	.read		= proc_coredump_filter_read,
2628 	.write		= proc_coredump_filter_write,
2629 	.llseek		= generic_file_llseek,
2630 };
2631 #endif
2632 
2633 #ifdef CONFIG_TASK_IO_ACCOUNTING
2634 static int do_io_accounting(struct task_struct *task, struct seq_file *m, int whole)
2635 {
2636 	struct task_io_accounting acct = task->ioac;
2637 	unsigned long flags;
2638 	int result;
2639 
2640 	result = mutex_lock_killable(&task->signal->cred_guard_mutex);
2641 	if (result)
2642 		return result;
2643 
2644 	if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) {
2645 		result = -EACCES;
2646 		goto out_unlock;
2647 	}
2648 
2649 	if (whole && lock_task_sighand(task, &flags)) {
2650 		struct task_struct *t = task;
2651 
2652 		task_io_accounting_add(&acct, &task->signal->ioac);
2653 		while_each_thread(task, t)
2654 			task_io_accounting_add(&acct, &t->ioac);
2655 
2656 		unlock_task_sighand(task, &flags);
2657 	}
2658 	seq_printf(m,
2659 		   "rchar: %llu\n"
2660 		   "wchar: %llu\n"
2661 		   "syscr: %llu\n"
2662 		   "syscw: %llu\n"
2663 		   "read_bytes: %llu\n"
2664 		   "write_bytes: %llu\n"
2665 		   "cancelled_write_bytes: %llu\n",
2666 		   (unsigned long long)acct.rchar,
2667 		   (unsigned long long)acct.wchar,
2668 		   (unsigned long long)acct.syscr,
2669 		   (unsigned long long)acct.syscw,
2670 		   (unsigned long long)acct.read_bytes,
2671 		   (unsigned long long)acct.write_bytes,
2672 		   (unsigned long long)acct.cancelled_write_bytes);
2673 	result = 0;
2674 
2675 out_unlock:
2676 	mutex_unlock(&task->signal->cred_guard_mutex);
2677 	return result;
2678 }
2679 
2680 static int proc_tid_io_accounting(struct seq_file *m, struct pid_namespace *ns,
2681 				  struct pid *pid, struct task_struct *task)
2682 {
2683 	return do_io_accounting(task, m, 0);
2684 }
2685 
2686 static int proc_tgid_io_accounting(struct seq_file *m, struct pid_namespace *ns,
2687 				   struct pid *pid, struct task_struct *task)
2688 {
2689 	return do_io_accounting(task, m, 1);
2690 }
2691 #endif /* CONFIG_TASK_IO_ACCOUNTING */
2692 
2693 #ifdef CONFIG_USER_NS
2694 static int proc_id_map_open(struct inode *inode, struct file *file,
2695 	const struct seq_operations *seq_ops)
2696 {
2697 	struct user_namespace *ns = NULL;
2698 	struct task_struct *task;
2699 	struct seq_file *seq;
2700 	int ret = -EINVAL;
2701 
2702 	task = get_proc_task(inode);
2703 	if (task) {
2704 		rcu_read_lock();
2705 		ns = get_user_ns(task_cred_xxx(task, user_ns));
2706 		rcu_read_unlock();
2707 		put_task_struct(task);
2708 	}
2709 	if (!ns)
2710 		goto err;
2711 
2712 	ret = seq_open(file, seq_ops);
2713 	if (ret)
2714 		goto err_put_ns;
2715 
2716 	seq = file->private_data;
2717 	seq->private = ns;
2718 
2719 	return 0;
2720 err_put_ns:
2721 	put_user_ns(ns);
2722 err:
2723 	return ret;
2724 }
2725 
2726 static int proc_id_map_release(struct inode *inode, struct file *file)
2727 {
2728 	struct seq_file *seq = file->private_data;
2729 	struct user_namespace *ns = seq->private;
2730 	put_user_ns(ns);
2731 	return seq_release(inode, file);
2732 }
2733 
2734 static int proc_uid_map_open(struct inode *inode, struct file *file)
2735 {
2736 	return proc_id_map_open(inode, file, &proc_uid_seq_operations);
2737 }
2738 
2739 static int proc_gid_map_open(struct inode *inode, struct file *file)
2740 {
2741 	return proc_id_map_open(inode, file, &proc_gid_seq_operations);
2742 }
2743 
2744 static int proc_projid_map_open(struct inode *inode, struct file *file)
2745 {
2746 	return proc_id_map_open(inode, file, &proc_projid_seq_operations);
2747 }
2748 
2749 static const struct file_operations proc_uid_map_operations = {
2750 	.open		= proc_uid_map_open,
2751 	.write		= proc_uid_map_write,
2752 	.read		= seq_read,
2753 	.llseek		= seq_lseek,
2754 	.release	= proc_id_map_release,
2755 };
2756 
2757 static const struct file_operations proc_gid_map_operations = {
2758 	.open		= proc_gid_map_open,
2759 	.write		= proc_gid_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_projid_map_operations = {
2766 	.open		= proc_projid_map_open,
2767 	.write		= proc_projid_map_write,
2768 	.read		= seq_read,
2769 	.llseek		= seq_lseek,
2770 	.release	= proc_id_map_release,
2771 };
2772 
2773 static int proc_setgroups_open(struct inode *inode, struct file *file)
2774 {
2775 	struct user_namespace *ns = NULL;
2776 	struct task_struct *task;
2777 	int ret;
2778 
2779 	ret = -ESRCH;
2780 	task = get_proc_task(inode);
2781 	if (task) {
2782 		rcu_read_lock();
2783 		ns = get_user_ns(task_cred_xxx(task, user_ns));
2784 		rcu_read_unlock();
2785 		put_task_struct(task);
2786 	}
2787 	if (!ns)
2788 		goto err;
2789 
2790 	if (file->f_mode & FMODE_WRITE) {
2791 		ret = -EACCES;
2792 		if (!ns_capable(ns, CAP_SYS_ADMIN))
2793 			goto err_put_ns;
2794 	}
2795 
2796 	ret = single_open(file, &proc_setgroups_show, ns);
2797 	if (ret)
2798 		goto err_put_ns;
2799 
2800 	return 0;
2801 err_put_ns:
2802 	put_user_ns(ns);
2803 err:
2804 	return ret;
2805 }
2806 
2807 static int proc_setgroups_release(struct inode *inode, struct file *file)
2808 {
2809 	struct seq_file *seq = file->private_data;
2810 	struct user_namespace *ns = seq->private;
2811 	int ret = single_release(inode, file);
2812 	put_user_ns(ns);
2813 	return ret;
2814 }
2815 
2816 static const struct file_operations proc_setgroups_operations = {
2817 	.open		= proc_setgroups_open,
2818 	.write		= proc_setgroups_write,
2819 	.read		= seq_read,
2820 	.llseek		= seq_lseek,
2821 	.release	= proc_setgroups_release,
2822 };
2823 #endif /* CONFIG_USER_NS */
2824 
2825 static int proc_pid_personality(struct seq_file *m, struct pid_namespace *ns,
2826 				struct pid *pid, struct task_struct *task)
2827 {
2828 	int err = lock_trace(task);
2829 	if (!err) {
2830 		seq_printf(m, "%08x\n", task->personality);
2831 		unlock_trace(task);
2832 	}
2833 	return err;
2834 }
2835 
2836 /*
2837  * Thread groups
2838  */
2839 static const struct file_operations proc_task_operations;
2840 static const struct inode_operations proc_task_inode_operations;
2841 
2842 static const struct pid_entry tgid_base_stuff[] = {
2843 	DIR("task",       S_IRUGO|S_IXUGO, proc_task_inode_operations, proc_task_operations),
2844 	DIR("fd",         S_IRUSR|S_IXUSR, proc_fd_inode_operations, proc_fd_operations),
2845 	DIR("map_files",  S_IRUSR|S_IXUSR, proc_map_files_inode_operations, proc_map_files_operations),
2846 	DIR("fdinfo",     S_IRUSR|S_IXUSR, proc_fdinfo_inode_operations, proc_fdinfo_operations),
2847 	DIR("ns",	  S_IRUSR|S_IXUGO, proc_ns_dir_inode_operations, proc_ns_dir_operations),
2848 #ifdef CONFIG_NET
2849 	DIR("net",        S_IRUGO|S_IXUGO, proc_net_inode_operations, proc_net_operations),
2850 #endif
2851 	REG("environ",    S_IRUSR, proc_environ_operations),
2852 	REG("auxv",       S_IRUSR, proc_auxv_operations),
2853 	ONE("status",     S_IRUGO, proc_pid_status),
2854 	ONE("personality", S_IRUSR, proc_pid_personality),
2855 	ONE("limits",	  S_IRUGO, proc_pid_limits),
2856 #ifdef CONFIG_SCHED_DEBUG
2857 	REG("sched",      S_IRUGO|S_IWUSR, proc_pid_sched_operations),
2858 #endif
2859 #ifdef CONFIG_SCHED_AUTOGROUP
2860 	REG("autogroup",  S_IRUGO|S_IWUSR, proc_pid_sched_autogroup_operations),
2861 #endif
2862 	REG("comm",      S_IRUGO|S_IWUSR, proc_pid_set_comm_operations),
2863 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
2864 	ONE("syscall",    S_IRUSR, proc_pid_syscall),
2865 #endif
2866 	REG("cmdline",    S_IRUGO, proc_pid_cmdline_ops),
2867 	ONE("stat",       S_IRUGO, proc_tgid_stat),
2868 	ONE("statm",      S_IRUGO, proc_pid_statm),
2869 	REG("maps",       S_IRUGO, proc_pid_maps_operations),
2870 #ifdef CONFIG_NUMA
2871 	REG("numa_maps",  S_IRUGO, proc_pid_numa_maps_operations),
2872 #endif
2873 	REG("mem",        S_IRUSR|S_IWUSR, proc_mem_operations),
2874 	LNK("cwd",        proc_cwd_link),
2875 	LNK("root",       proc_root_link),
2876 	LNK("exe",        proc_exe_link),
2877 	REG("mounts",     S_IRUGO, proc_mounts_operations),
2878 	REG("mountinfo",  S_IRUGO, proc_mountinfo_operations),
2879 	REG("mountstats", S_IRUSR, proc_mountstats_operations),
2880 #ifdef CONFIG_PROC_PAGE_MONITOR
2881 	REG("clear_refs", S_IWUSR, proc_clear_refs_operations),
2882 	REG("smaps",      S_IRUGO, proc_pid_smaps_operations),
2883 	REG("pagemap",    S_IRUSR, proc_pagemap_operations),
2884 #endif
2885 #ifdef CONFIG_SECURITY
2886 	DIR("attr",       S_IRUGO|S_IXUGO, proc_attr_dir_inode_operations, proc_attr_dir_operations),
2887 #endif
2888 #ifdef CONFIG_KALLSYMS
2889 	ONE("wchan",      S_IRUGO, proc_pid_wchan),
2890 #endif
2891 #ifdef CONFIG_STACKTRACE
2892 	ONE("stack",      S_IRUSR, proc_pid_stack),
2893 #endif
2894 #ifdef CONFIG_SCHED_INFO
2895 	ONE("schedstat",  S_IRUGO, proc_pid_schedstat),
2896 #endif
2897 #ifdef CONFIG_LATENCYTOP
2898 	REG("latency",  S_IRUGO, proc_lstats_operations),
2899 #endif
2900 #ifdef CONFIG_PROC_PID_CPUSET
2901 	ONE("cpuset",     S_IRUGO, proc_cpuset_show),
2902 #endif
2903 #ifdef CONFIG_CGROUPS
2904 	ONE("cgroup",  S_IRUGO, proc_cgroup_show),
2905 #endif
2906 	ONE("oom_score",  S_IRUGO, proc_oom_score),
2907 	REG("oom_adj",    S_IRUGO|S_IWUSR, proc_oom_adj_operations),
2908 	REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
2909 #ifdef CONFIG_AUDITSYSCALL
2910 	REG("loginuid",   S_IWUSR|S_IRUGO, proc_loginuid_operations),
2911 	REG("sessionid",  S_IRUGO, proc_sessionid_operations),
2912 #endif
2913 #ifdef CONFIG_FAULT_INJECTION
2914 	REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
2915 #endif
2916 #ifdef CONFIG_ELF_CORE
2917 	REG("coredump_filter", S_IRUGO|S_IWUSR, proc_coredump_filter_operations),
2918 #endif
2919 #ifdef CONFIG_TASK_IO_ACCOUNTING
2920 	ONE("io",	S_IRUSR, proc_tgid_io_accounting),
2921 #endif
2922 #ifdef CONFIG_HARDWALL
2923 	ONE("hardwall",   S_IRUGO, proc_pid_hardwall),
2924 #endif
2925 #ifdef CONFIG_USER_NS
2926 	REG("uid_map",    S_IRUGO|S_IWUSR, proc_uid_map_operations),
2927 	REG("gid_map",    S_IRUGO|S_IWUSR, proc_gid_map_operations),
2928 	REG("projid_map", S_IRUGO|S_IWUSR, proc_projid_map_operations),
2929 	REG("setgroups",  S_IRUGO|S_IWUSR, proc_setgroups_operations),
2930 #endif
2931 #ifdef CONFIG_CHECKPOINT_RESTORE
2932 	REG("timers",	  S_IRUGO, proc_timers_operations),
2933 #endif
2934 	REG("timerslack_ns", S_IRUGO|S_IWUGO, proc_pid_set_timerslack_ns_operations),
2935 };
2936 
2937 static int proc_tgid_base_readdir(struct file *file, struct dir_context *ctx)
2938 {
2939 	return proc_pident_readdir(file, ctx,
2940 				   tgid_base_stuff, ARRAY_SIZE(tgid_base_stuff));
2941 }
2942 
2943 static const struct file_operations proc_tgid_base_operations = {
2944 	.read		= generic_read_dir,
2945 	.iterate_shared	= proc_tgid_base_readdir,
2946 	.llseek		= generic_file_llseek,
2947 };
2948 
2949 static struct dentry *proc_tgid_base_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
2950 {
2951 	return proc_pident_lookup(dir, dentry,
2952 				  tgid_base_stuff, ARRAY_SIZE(tgid_base_stuff));
2953 }
2954 
2955 static const struct inode_operations proc_tgid_base_inode_operations = {
2956 	.lookup		= proc_tgid_base_lookup,
2957 	.getattr	= pid_getattr,
2958 	.setattr	= proc_setattr,
2959 	.permission	= proc_pid_permission,
2960 };
2961 
2962 static void proc_flush_task_mnt(struct vfsmount *mnt, pid_t pid, pid_t tgid)
2963 {
2964 	struct dentry *dentry, *leader, *dir;
2965 	char buf[PROC_NUMBUF];
2966 	struct qstr name;
2967 
2968 	name.name = buf;
2969 	name.len = snprintf(buf, sizeof(buf), "%d", pid);
2970 	/* no ->d_hash() rejects on procfs */
2971 	dentry = d_hash_and_lookup(mnt->mnt_root, &name);
2972 	if (dentry) {
2973 		d_invalidate(dentry);
2974 		dput(dentry);
2975 	}
2976 
2977 	if (pid == tgid)
2978 		return;
2979 
2980 	name.name = buf;
2981 	name.len = snprintf(buf, sizeof(buf), "%d", tgid);
2982 	leader = d_hash_and_lookup(mnt->mnt_root, &name);
2983 	if (!leader)
2984 		goto out;
2985 
2986 	name.name = "task";
2987 	name.len = strlen(name.name);
2988 	dir = d_hash_and_lookup(leader, &name);
2989 	if (!dir)
2990 		goto out_put_leader;
2991 
2992 	name.name = buf;
2993 	name.len = snprintf(buf, sizeof(buf), "%d", pid);
2994 	dentry = d_hash_and_lookup(dir, &name);
2995 	if (dentry) {
2996 		d_invalidate(dentry);
2997 		dput(dentry);
2998 	}
2999 
3000 	dput(dir);
3001 out_put_leader:
3002 	dput(leader);
3003 out:
3004 	return;
3005 }
3006 
3007 /**
3008  * proc_flush_task -  Remove dcache entries for @task from the /proc dcache.
3009  * @task: task that should be flushed.
3010  *
3011  * When flushing dentries from proc, one needs to flush them from global
3012  * proc (proc_mnt) and from all the namespaces' procs this task was seen
3013  * in. This call is supposed to do all of this job.
3014  *
3015  * Looks in the dcache for
3016  * /proc/@pid
3017  * /proc/@tgid/task/@pid
3018  * if either directory is present flushes it and all of it'ts children
3019  * from the dcache.
3020  *
3021  * It is safe and reasonable to cache /proc entries for a task until
3022  * that task exits.  After that they just clog up the dcache with
3023  * useless entries, possibly causing useful dcache entries to be
3024  * flushed instead.  This routine is proved to flush those useless
3025  * dcache entries at process exit time.
3026  *
3027  * NOTE: This routine is just an optimization so it does not guarantee
3028  *       that no dcache entries will exist at process exit time it
3029  *       just makes it very unlikely that any will persist.
3030  */
3031 
3032 void proc_flush_task(struct task_struct *task)
3033 {
3034 	int i;
3035 	struct pid *pid, *tgid;
3036 	struct upid *upid;
3037 
3038 	pid = task_pid(task);
3039 	tgid = task_tgid(task);
3040 
3041 	for (i = 0; i <= pid->level; i++) {
3042 		upid = &pid->numbers[i];
3043 		proc_flush_task_mnt(upid->ns->proc_mnt, upid->nr,
3044 					tgid->numbers[i].nr);
3045 	}
3046 }
3047 
3048 static int proc_pid_instantiate(struct inode *dir,
3049 				   struct dentry * dentry,
3050 				   struct task_struct *task, const void *ptr)
3051 {
3052 	struct inode *inode;
3053 
3054 	inode = proc_pid_make_inode(dir->i_sb, task);
3055 	if (!inode)
3056 		goto out;
3057 
3058 	inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
3059 	inode->i_op = &proc_tgid_base_inode_operations;
3060 	inode->i_fop = &proc_tgid_base_operations;
3061 	inode->i_flags|=S_IMMUTABLE;
3062 
3063 	set_nlink(inode, 2 + pid_entry_count_dirs(tgid_base_stuff,
3064 						  ARRAY_SIZE(tgid_base_stuff)));
3065 
3066 	d_set_d_op(dentry, &pid_dentry_operations);
3067 
3068 	d_add(dentry, inode);
3069 	/* Close the race of the process dying before we return the dentry */
3070 	if (pid_revalidate(dentry, 0))
3071 		return 0;
3072 out:
3073 	return -ENOENT;
3074 }
3075 
3076 struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)
3077 {
3078 	int result = -ENOENT;
3079 	struct task_struct *task;
3080 	unsigned tgid;
3081 	struct pid_namespace *ns;
3082 
3083 	tgid = name_to_int(&dentry->d_name);
3084 	if (tgid == ~0U)
3085 		goto out;
3086 
3087 	ns = dentry->d_sb->s_fs_info;
3088 	rcu_read_lock();
3089 	task = find_task_by_pid_ns(tgid, ns);
3090 	if (task)
3091 		get_task_struct(task);
3092 	rcu_read_unlock();
3093 	if (!task)
3094 		goto out;
3095 
3096 	result = proc_pid_instantiate(dir, dentry, task, NULL);
3097 	put_task_struct(task);
3098 out:
3099 	return ERR_PTR(result);
3100 }
3101 
3102 /*
3103  * Find the first task with tgid >= tgid
3104  *
3105  */
3106 struct tgid_iter {
3107 	unsigned int tgid;
3108 	struct task_struct *task;
3109 };
3110 static struct tgid_iter next_tgid(struct pid_namespace *ns, struct tgid_iter iter)
3111 {
3112 	struct pid *pid;
3113 
3114 	if (iter.task)
3115 		put_task_struct(iter.task);
3116 	rcu_read_lock();
3117 retry:
3118 	iter.task = NULL;
3119 	pid = find_ge_pid(iter.tgid, ns);
3120 	if (pid) {
3121 		iter.tgid = pid_nr_ns(pid, ns);
3122 		iter.task = pid_task(pid, PIDTYPE_PID);
3123 		/* What we to know is if the pid we have find is the
3124 		 * pid of a thread_group_leader.  Testing for task
3125 		 * being a thread_group_leader is the obvious thing
3126 		 * todo but there is a window when it fails, due to
3127 		 * the pid transfer logic in de_thread.
3128 		 *
3129 		 * So we perform the straight forward test of seeing
3130 		 * if the pid we have found is the pid of a thread
3131 		 * group leader, and don't worry if the task we have
3132 		 * found doesn't happen to be a thread group leader.
3133 		 * As we don't care in the case of readdir.
3134 		 */
3135 		if (!iter.task || !has_group_leader_pid(iter.task)) {
3136 			iter.tgid += 1;
3137 			goto retry;
3138 		}
3139 		get_task_struct(iter.task);
3140 	}
3141 	rcu_read_unlock();
3142 	return iter;
3143 }
3144 
3145 #define TGID_OFFSET (FIRST_PROCESS_ENTRY + 2)
3146 
3147 /* for the /proc/ directory itself, after non-process stuff has been done */
3148 int proc_pid_readdir(struct file *file, struct dir_context *ctx)
3149 {
3150 	struct tgid_iter iter;
3151 	struct pid_namespace *ns = file_inode(file)->i_sb->s_fs_info;
3152 	loff_t pos = ctx->pos;
3153 
3154 	if (pos >= PID_MAX_LIMIT + TGID_OFFSET)
3155 		return 0;
3156 
3157 	if (pos == TGID_OFFSET - 2) {
3158 		struct inode *inode = d_inode(ns->proc_self);
3159 		if (!dir_emit(ctx, "self", 4, inode->i_ino, DT_LNK))
3160 			return 0;
3161 		ctx->pos = pos = pos + 1;
3162 	}
3163 	if (pos == TGID_OFFSET - 1) {
3164 		struct inode *inode = d_inode(ns->proc_thread_self);
3165 		if (!dir_emit(ctx, "thread-self", 11, inode->i_ino, DT_LNK))
3166 			return 0;
3167 		ctx->pos = pos = pos + 1;
3168 	}
3169 	iter.tgid = pos - TGID_OFFSET;
3170 	iter.task = NULL;
3171 	for (iter = next_tgid(ns, iter);
3172 	     iter.task;
3173 	     iter.tgid += 1, iter = next_tgid(ns, iter)) {
3174 		char name[PROC_NUMBUF];
3175 		int len;
3176 		if (!has_pid_permissions(ns, iter.task, 2))
3177 			continue;
3178 
3179 		len = snprintf(name, sizeof(name), "%d", iter.tgid);
3180 		ctx->pos = iter.tgid + TGID_OFFSET;
3181 		if (!proc_fill_cache(file, ctx, name, len,
3182 				     proc_pid_instantiate, iter.task, NULL)) {
3183 			put_task_struct(iter.task);
3184 			return 0;
3185 		}
3186 	}
3187 	ctx->pos = PID_MAX_LIMIT + TGID_OFFSET;
3188 	return 0;
3189 }
3190 
3191 /*
3192  * proc_tid_comm_permission is a special permission function exclusively
3193  * used for the node /proc/<pid>/task/<tid>/comm.
3194  * It bypasses generic permission checks in the case where a task of the same
3195  * task group attempts to access the node.
3196  * The rationale behind this is that glibc and bionic access this node for
3197  * cross thread naming (pthread_set/getname_np(!self)). However, if
3198  * PR_SET_DUMPABLE gets set to 0 this node among others becomes uid=0 gid=0,
3199  * which locks out the cross thread naming implementation.
3200  * This function makes sure that the node is always accessible for members of
3201  * same thread group.
3202  */
3203 static int proc_tid_comm_permission(struct inode *inode, int mask)
3204 {
3205 	bool is_same_tgroup;
3206 	struct task_struct *task;
3207 
3208 	task = get_proc_task(inode);
3209 	if (!task)
3210 		return -ESRCH;
3211 	is_same_tgroup = same_thread_group(current, task);
3212 	put_task_struct(task);
3213 
3214 	if (likely(is_same_tgroup && !(mask & MAY_EXEC))) {
3215 		/* This file (/proc/<pid>/task/<tid>/comm) can always be
3216 		 * read or written by the members of the corresponding
3217 		 * thread group.
3218 		 */
3219 		return 0;
3220 	}
3221 
3222 	return generic_permission(inode, mask);
3223 }
3224 
3225 static const struct inode_operations proc_tid_comm_inode_operations = {
3226 		.permission = proc_tid_comm_permission,
3227 };
3228 
3229 /*
3230  * Tasks
3231  */
3232 static const struct pid_entry tid_base_stuff[] = {
3233 	DIR("fd",        S_IRUSR|S_IXUSR, proc_fd_inode_operations, proc_fd_operations),
3234 	DIR("fdinfo",    S_IRUSR|S_IXUSR, proc_fdinfo_inode_operations, proc_fdinfo_operations),
3235 	DIR("ns",	 S_IRUSR|S_IXUGO, proc_ns_dir_inode_operations, proc_ns_dir_operations),
3236 #ifdef CONFIG_NET
3237 	DIR("net",        S_IRUGO|S_IXUGO, proc_net_inode_operations, proc_net_operations),
3238 #endif
3239 	REG("environ",   S_IRUSR, proc_environ_operations),
3240 	REG("auxv",      S_IRUSR, proc_auxv_operations),
3241 	ONE("status",    S_IRUGO, proc_pid_status),
3242 	ONE("personality", S_IRUSR, proc_pid_personality),
3243 	ONE("limits",	 S_IRUGO, proc_pid_limits),
3244 #ifdef CONFIG_SCHED_DEBUG
3245 	REG("sched",     S_IRUGO|S_IWUSR, proc_pid_sched_operations),
3246 #endif
3247 	NOD("comm",      S_IFREG|S_IRUGO|S_IWUSR,
3248 			 &proc_tid_comm_inode_operations,
3249 			 &proc_pid_set_comm_operations, {}),
3250 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
3251 	ONE("syscall",   S_IRUSR, proc_pid_syscall),
3252 #endif
3253 	REG("cmdline",   S_IRUGO, proc_pid_cmdline_ops),
3254 	ONE("stat",      S_IRUGO, proc_tid_stat),
3255 	ONE("statm",     S_IRUGO, proc_pid_statm),
3256 	REG("maps",      S_IRUGO, proc_tid_maps_operations),
3257 #ifdef CONFIG_PROC_CHILDREN
3258 	REG("children",  S_IRUGO, proc_tid_children_operations),
3259 #endif
3260 #ifdef CONFIG_NUMA
3261 	REG("numa_maps", S_IRUGO, proc_tid_numa_maps_operations),
3262 #endif
3263 	REG("mem",       S_IRUSR|S_IWUSR, proc_mem_operations),
3264 	LNK("cwd",       proc_cwd_link),
3265 	LNK("root",      proc_root_link),
3266 	LNK("exe",       proc_exe_link),
3267 	REG("mounts",    S_IRUGO, proc_mounts_operations),
3268 	REG("mountinfo",  S_IRUGO, proc_mountinfo_operations),
3269 #ifdef CONFIG_PROC_PAGE_MONITOR
3270 	REG("clear_refs", S_IWUSR, proc_clear_refs_operations),
3271 	REG("smaps",     S_IRUGO, proc_tid_smaps_operations),
3272 	REG("pagemap",    S_IRUSR, proc_pagemap_operations),
3273 #endif
3274 #ifdef CONFIG_SECURITY
3275 	DIR("attr",      S_IRUGO|S_IXUGO, proc_attr_dir_inode_operations, proc_attr_dir_operations),
3276 #endif
3277 #ifdef CONFIG_KALLSYMS
3278 	ONE("wchan",     S_IRUGO, proc_pid_wchan),
3279 #endif
3280 #ifdef CONFIG_STACKTRACE
3281 	ONE("stack",      S_IRUSR, proc_pid_stack),
3282 #endif
3283 #ifdef CONFIG_SCHED_INFO
3284 	ONE("schedstat", S_IRUGO, proc_pid_schedstat),
3285 #endif
3286 #ifdef CONFIG_LATENCYTOP
3287 	REG("latency",  S_IRUGO, proc_lstats_operations),
3288 #endif
3289 #ifdef CONFIG_PROC_PID_CPUSET
3290 	ONE("cpuset",    S_IRUGO, proc_cpuset_show),
3291 #endif
3292 #ifdef CONFIG_CGROUPS
3293 	ONE("cgroup",  S_IRUGO, proc_cgroup_show),
3294 #endif
3295 	ONE("oom_score", S_IRUGO, proc_oom_score),
3296 	REG("oom_adj",   S_IRUGO|S_IWUSR, proc_oom_adj_operations),
3297 	REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
3298 #ifdef CONFIG_AUDITSYSCALL
3299 	REG("loginuid",  S_IWUSR|S_IRUGO, proc_loginuid_operations),
3300 	REG("sessionid",  S_IRUGO, proc_sessionid_operations),
3301 #endif
3302 #ifdef CONFIG_FAULT_INJECTION
3303 	REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
3304 #endif
3305 #ifdef CONFIG_TASK_IO_ACCOUNTING
3306 	ONE("io",	S_IRUSR, proc_tid_io_accounting),
3307 #endif
3308 #ifdef CONFIG_HARDWALL
3309 	ONE("hardwall",   S_IRUGO, proc_pid_hardwall),
3310 #endif
3311 #ifdef CONFIG_USER_NS
3312 	REG("uid_map",    S_IRUGO|S_IWUSR, proc_uid_map_operations),
3313 	REG("gid_map",    S_IRUGO|S_IWUSR, proc_gid_map_operations),
3314 	REG("projid_map", S_IRUGO|S_IWUSR, proc_projid_map_operations),
3315 	REG("setgroups",  S_IRUGO|S_IWUSR, proc_setgroups_operations),
3316 #endif
3317 };
3318 
3319 static int proc_tid_base_readdir(struct file *file, struct dir_context *ctx)
3320 {
3321 	return proc_pident_readdir(file, ctx,
3322 				   tid_base_stuff, ARRAY_SIZE(tid_base_stuff));
3323 }
3324 
3325 static struct dentry *proc_tid_base_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
3326 {
3327 	return proc_pident_lookup(dir, dentry,
3328 				  tid_base_stuff, ARRAY_SIZE(tid_base_stuff));
3329 }
3330 
3331 static const struct file_operations proc_tid_base_operations = {
3332 	.read		= generic_read_dir,
3333 	.iterate_shared	= proc_tid_base_readdir,
3334 	.llseek		= generic_file_llseek,
3335 };
3336 
3337 static const struct inode_operations proc_tid_base_inode_operations = {
3338 	.lookup		= proc_tid_base_lookup,
3339 	.getattr	= pid_getattr,
3340 	.setattr	= proc_setattr,
3341 };
3342 
3343 static int proc_task_instantiate(struct inode *dir,
3344 	struct dentry *dentry, struct task_struct *task, const void *ptr)
3345 {
3346 	struct inode *inode;
3347 	inode = proc_pid_make_inode(dir->i_sb, task);
3348 
3349 	if (!inode)
3350 		goto out;
3351 	inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
3352 	inode->i_op = &proc_tid_base_inode_operations;
3353 	inode->i_fop = &proc_tid_base_operations;
3354 	inode->i_flags|=S_IMMUTABLE;
3355 
3356 	set_nlink(inode, 2 + pid_entry_count_dirs(tid_base_stuff,
3357 						  ARRAY_SIZE(tid_base_stuff)));
3358 
3359 	d_set_d_op(dentry, &pid_dentry_operations);
3360 
3361 	d_add(dentry, inode);
3362 	/* Close the race of the process dying before we return the dentry */
3363 	if (pid_revalidate(dentry, 0))
3364 		return 0;
3365 out:
3366 	return -ENOENT;
3367 }
3368 
3369 static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)
3370 {
3371 	int result = -ENOENT;
3372 	struct task_struct *task;
3373 	struct task_struct *leader = get_proc_task(dir);
3374 	unsigned tid;
3375 	struct pid_namespace *ns;
3376 
3377 	if (!leader)
3378 		goto out_no_task;
3379 
3380 	tid = name_to_int(&dentry->d_name);
3381 	if (tid == ~0U)
3382 		goto out;
3383 
3384 	ns = dentry->d_sb->s_fs_info;
3385 	rcu_read_lock();
3386 	task = find_task_by_pid_ns(tid, ns);
3387 	if (task)
3388 		get_task_struct(task);
3389 	rcu_read_unlock();
3390 	if (!task)
3391 		goto out;
3392 	if (!same_thread_group(leader, task))
3393 		goto out_drop_task;
3394 
3395 	result = proc_task_instantiate(dir, dentry, task, NULL);
3396 out_drop_task:
3397 	put_task_struct(task);
3398 out:
3399 	put_task_struct(leader);
3400 out_no_task:
3401 	return ERR_PTR(result);
3402 }
3403 
3404 /*
3405  * Find the first tid of a thread group to return to user space.
3406  *
3407  * Usually this is just the thread group leader, but if the users
3408  * buffer was too small or there was a seek into the middle of the
3409  * directory we have more work todo.
3410  *
3411  * In the case of a short read we start with find_task_by_pid.
3412  *
3413  * In the case of a seek we start with the leader and walk nr
3414  * threads past it.
3415  */
3416 static struct task_struct *first_tid(struct pid *pid, int tid, loff_t f_pos,
3417 					struct pid_namespace *ns)
3418 {
3419 	struct task_struct *pos, *task;
3420 	unsigned long nr = f_pos;
3421 
3422 	if (nr != f_pos)	/* 32bit overflow? */
3423 		return NULL;
3424 
3425 	rcu_read_lock();
3426 	task = pid_task(pid, PIDTYPE_PID);
3427 	if (!task)
3428 		goto fail;
3429 
3430 	/* Attempt to start with the tid of a thread */
3431 	if (tid && nr) {
3432 		pos = find_task_by_pid_ns(tid, ns);
3433 		if (pos && same_thread_group(pos, task))
3434 			goto found;
3435 	}
3436 
3437 	/* If nr exceeds the number of threads there is nothing todo */
3438 	if (nr >= get_nr_threads(task))
3439 		goto fail;
3440 
3441 	/* If we haven't found our starting place yet start
3442 	 * with the leader and walk nr threads forward.
3443 	 */
3444 	pos = task = task->group_leader;
3445 	do {
3446 		if (!nr--)
3447 			goto found;
3448 	} while_each_thread(task, pos);
3449 fail:
3450 	pos = NULL;
3451 	goto out;
3452 found:
3453 	get_task_struct(pos);
3454 out:
3455 	rcu_read_unlock();
3456 	return pos;
3457 }
3458 
3459 /*
3460  * Find the next thread in the thread list.
3461  * Return NULL if there is an error or no next thread.
3462  *
3463  * The reference to the input task_struct is released.
3464  */
3465 static struct task_struct *next_tid(struct task_struct *start)
3466 {
3467 	struct task_struct *pos = NULL;
3468 	rcu_read_lock();
3469 	if (pid_alive(start)) {
3470 		pos = next_thread(start);
3471 		if (thread_group_leader(pos))
3472 			pos = NULL;
3473 		else
3474 			get_task_struct(pos);
3475 	}
3476 	rcu_read_unlock();
3477 	put_task_struct(start);
3478 	return pos;
3479 }
3480 
3481 /* for the /proc/TGID/task/ directories */
3482 static int proc_task_readdir(struct file *file, struct dir_context *ctx)
3483 {
3484 	struct inode *inode = file_inode(file);
3485 	struct task_struct *task;
3486 	struct pid_namespace *ns;
3487 	int tid;
3488 
3489 	if (proc_inode_is_dead(inode))
3490 		return -ENOENT;
3491 
3492 	if (!dir_emit_dots(file, ctx))
3493 		return 0;
3494 
3495 	/* f_version caches the tgid value that the last readdir call couldn't
3496 	 * return. lseek aka telldir automagically resets f_version to 0.
3497 	 */
3498 	ns = inode->i_sb->s_fs_info;
3499 	tid = (int)file->f_version;
3500 	file->f_version = 0;
3501 	for (task = first_tid(proc_pid(inode), tid, ctx->pos - 2, ns);
3502 	     task;
3503 	     task = next_tid(task), ctx->pos++) {
3504 		char name[PROC_NUMBUF];
3505 		int len;
3506 		tid = task_pid_nr_ns(task, ns);
3507 		len = snprintf(name, sizeof(name), "%d", tid);
3508 		if (!proc_fill_cache(file, ctx, name, len,
3509 				proc_task_instantiate, task, NULL)) {
3510 			/* returning this tgid failed, save it as the first
3511 			 * pid for the next readir call */
3512 			file->f_version = (u64)tid;
3513 			put_task_struct(task);
3514 			break;
3515 		}
3516 	}
3517 
3518 	return 0;
3519 }
3520 
3521 static int proc_task_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
3522 {
3523 	struct inode *inode = d_inode(dentry);
3524 	struct task_struct *p = get_proc_task(inode);
3525 	generic_fillattr(inode, stat);
3526 
3527 	if (p) {
3528 		stat->nlink += get_nr_threads(p);
3529 		put_task_struct(p);
3530 	}
3531 
3532 	return 0;
3533 }
3534 
3535 static const struct inode_operations proc_task_inode_operations = {
3536 	.lookup		= proc_task_lookup,
3537 	.getattr	= proc_task_getattr,
3538 	.setattr	= proc_setattr,
3539 	.permission	= proc_pid_permission,
3540 };
3541 
3542 static const struct file_operations proc_task_operations = {
3543 	.read		= generic_read_dir,
3544 	.iterate_shared	= proc_task_readdir,
3545 	.llseek		= generic_file_llseek,
3546 };
3547