xref: /openbmc/linux/fs/proc/base.c (revision 4a3fad70)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/fs/proc/base.c
4  *
5  *  Copyright (C) 1991, 1992 Linus Torvalds
6  *
7  *  proc base directory handling functions
8  *
9  *  1999, Al Viro. Rewritten. Now it covers the whole per-process part.
10  *  Instead of using magical inumbers to determine the kind of object
11  *  we allocate and fill in-core inodes upon lookup. They don't even
12  *  go into icache. We cache the reference to task_struct upon lookup too.
13  *  Eventually it should become a filesystem in its own. We don't use the
14  *  rest of procfs anymore.
15  *
16  *
17  *  Changelog:
18  *  17-Jan-2005
19  *  Allan Bezerra
20  *  Bruna Moreira <bruna.moreira@indt.org.br>
21  *  Edjard Mota <edjard.mota@indt.org.br>
22  *  Ilias Biris <ilias.biris@indt.org.br>
23  *  Mauricio Lin <mauricio.lin@indt.org.br>
24  *
25  *  Embedded Linux Lab - 10LE Instituto Nokia de Tecnologia - INdT
26  *
27  *  A new process specific entry (smaps) included in /proc. It shows the
28  *  size of rss for each memory area. The maps entry lacks information
29  *  about physical memory size (rss) for each mapped file, i.e.,
30  *  rss information for executables and library files.
31  *  This additional information is useful for any tools that need to know
32  *  about physical memory consumption for a process specific library.
33  *
34  *  Changelog:
35  *  21-Feb-2005
36  *  Embedded Linux Lab - 10LE Instituto Nokia de Tecnologia - INdT
37  *  Pud inclusion in the page table walking.
38  *
39  *  ChangeLog:
40  *  10-Mar-2005
41  *  10LE Instituto Nokia de Tecnologia - INdT:
42  *  A better way to walks through the page table as suggested by Hugh Dickins.
43  *
44  *  Simo Piiroinen <simo.piiroinen@nokia.com>:
45  *  Smaps information related to shared, private, clean and dirty pages.
46  *
47  *  Paul Mundt <paul.mundt@nokia.com>:
48  *  Overall revision about smaps.
49  */
50 
51 #include <linux/uaccess.h>
52 
53 #include <linux/errno.h>
54 #include <linux/time.h>
55 #include <linux/proc_fs.h>
56 #include <linux/stat.h>
57 #include <linux/task_io_accounting_ops.h>
58 #include <linux/init.h>
59 #include <linux/capability.h>
60 #include <linux/file.h>
61 #include <linux/fdtable.h>
62 #include <linux/string.h>
63 #include <linux/seq_file.h>
64 #include <linux/namei.h>
65 #include <linux/mnt_namespace.h>
66 #include <linux/mm.h>
67 #include <linux/swap.h>
68 #include <linux/rcupdate.h>
69 #include <linux/kallsyms.h>
70 #include <linux/stacktrace.h>
71 #include <linux/resource.h>
72 #include <linux/module.h>
73 #include <linux/mount.h>
74 #include <linux/security.h>
75 #include <linux/ptrace.h>
76 #include <linux/tracehook.h>
77 #include <linux/printk.h>
78 #include <linux/cgroup.h>
79 #include <linux/cpuset.h>
80 #include <linux/audit.h>
81 #include <linux/poll.h>
82 #include <linux/nsproxy.h>
83 #include <linux/oom.h>
84 #include <linux/elf.h>
85 #include <linux/pid_namespace.h>
86 #include <linux/user_namespace.h>
87 #include <linux/fs_struct.h>
88 #include <linux/slab.h>
89 #include <linux/sched/autogroup.h>
90 #include <linux/sched/mm.h>
91 #include <linux/sched/coredump.h>
92 #include <linux/sched/debug.h>
93 #include <linux/sched/stat.h>
94 #include <linux/flex_array.h>
95 #include <linux/posix-timers.h>
96 #ifdef CONFIG_HARDWALL
97 #include <asm/hardwall.h>
98 #endif
99 #include <trace/events/oom.h>
100 #include "internal.h"
101 #include "fd.h"
102 
103 /* NOTE:
104  *	Implementing inode permission operations in /proc is almost
105  *	certainly an error.  Permission checks need to happen during
106  *	each system call not at open time.  The reason is that most of
107  *	what we wish to check for permissions in /proc varies at runtime.
108  *
109  *	The classic example of a problem is opening file descriptors
110  *	in /proc for a task before it execs a suid executable.
111  */
112 
113 static u8 nlink_tid;
114 static u8 nlink_tgid;
115 
116 struct pid_entry {
117 	const char *name;
118 	unsigned int len;
119 	umode_t mode;
120 	const struct inode_operations *iop;
121 	const struct file_operations *fop;
122 	union proc_op op;
123 };
124 
125 #define NOD(NAME, MODE, IOP, FOP, OP) {			\
126 	.name = (NAME),					\
127 	.len  = sizeof(NAME) - 1,			\
128 	.mode = MODE,					\
129 	.iop  = IOP,					\
130 	.fop  = FOP,					\
131 	.op   = OP,					\
132 }
133 
134 #define DIR(NAME, MODE, iops, fops)	\
135 	NOD(NAME, (S_IFDIR|(MODE)), &iops, &fops, {} )
136 #define LNK(NAME, get_link)					\
137 	NOD(NAME, (S_IFLNK|S_IRWXUGO),				\
138 		&proc_pid_link_inode_operations, NULL,		\
139 		{ .proc_get_link = get_link } )
140 #define REG(NAME, MODE, fops)				\
141 	NOD(NAME, (S_IFREG|(MODE)), NULL, &fops, {})
142 #define ONE(NAME, MODE, show)				\
143 	NOD(NAME, (S_IFREG|(MODE)), 			\
144 		NULL, &proc_single_file_operations,	\
145 		{ .proc_show = show } )
146 
147 /*
148  * Count the number of hardlinks for the pid_entry table, excluding the .
149  * and .. links.
150  */
151 static unsigned int __init pid_entry_nlink(const struct pid_entry *entries,
152 	unsigned int n)
153 {
154 	unsigned int i;
155 	unsigned int count;
156 
157 	count = 2;
158 	for (i = 0; i < n; ++i) {
159 		if (S_ISDIR(entries[i].mode))
160 			++count;
161 	}
162 
163 	return count;
164 }
165 
166 static int get_task_root(struct task_struct *task, struct path *root)
167 {
168 	int result = -ENOENT;
169 
170 	task_lock(task);
171 	if (task->fs) {
172 		get_fs_root(task->fs, root);
173 		result = 0;
174 	}
175 	task_unlock(task);
176 	return result;
177 }
178 
179 static int proc_cwd_link(struct dentry *dentry, struct path *path)
180 {
181 	struct task_struct *task = get_proc_task(d_inode(dentry));
182 	int result = -ENOENT;
183 
184 	if (task) {
185 		task_lock(task);
186 		if (task->fs) {
187 			get_fs_pwd(task->fs, path);
188 			result = 0;
189 		}
190 		task_unlock(task);
191 		put_task_struct(task);
192 	}
193 	return result;
194 }
195 
196 static int proc_root_link(struct dentry *dentry, struct path *path)
197 {
198 	struct task_struct *task = get_proc_task(d_inode(dentry));
199 	int result = -ENOENT;
200 
201 	if (task) {
202 		result = get_task_root(task, path);
203 		put_task_struct(task);
204 	}
205 	return result;
206 }
207 
208 static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
209 				     size_t _count, loff_t *pos)
210 {
211 	struct task_struct *tsk;
212 	struct mm_struct *mm;
213 	char *page;
214 	unsigned long count = _count;
215 	unsigned long arg_start, arg_end, env_start, env_end;
216 	unsigned long len1, len2, len;
217 	unsigned long p;
218 	char c;
219 	ssize_t rv;
220 
221 	BUG_ON(*pos < 0);
222 
223 	tsk = get_proc_task(file_inode(file));
224 	if (!tsk)
225 		return -ESRCH;
226 	mm = get_task_mm(tsk);
227 	put_task_struct(tsk);
228 	if (!mm)
229 		return 0;
230 	/* Check if process spawned far enough to have cmdline. */
231 	if (!mm->env_end) {
232 		rv = 0;
233 		goto out_mmput;
234 	}
235 
236 	page = (char *)__get_free_page(GFP_KERNEL);
237 	if (!page) {
238 		rv = -ENOMEM;
239 		goto out_mmput;
240 	}
241 
242 	down_read(&mm->mmap_sem);
243 	arg_start = mm->arg_start;
244 	arg_end = mm->arg_end;
245 	env_start = mm->env_start;
246 	env_end = mm->env_end;
247 	up_read(&mm->mmap_sem);
248 
249 	BUG_ON(arg_start > arg_end);
250 	BUG_ON(env_start > env_end);
251 
252 	len1 = arg_end - arg_start;
253 	len2 = env_end - env_start;
254 
255 	/* Empty ARGV. */
256 	if (len1 == 0) {
257 		rv = 0;
258 		goto out_free_page;
259 	}
260 	/*
261 	 * Inherently racy -- command line shares address space
262 	 * with code and data.
263 	 */
264 	rv = access_remote_vm(mm, arg_end - 1, &c, 1, 0);
265 	if (rv <= 0)
266 		goto out_free_page;
267 
268 	rv = 0;
269 
270 	if (c == '\0') {
271 		/* Command line (set of strings) occupies whole ARGV. */
272 		if (len1 <= *pos)
273 			goto out_free_page;
274 
275 		p = arg_start + *pos;
276 		len = len1 - *pos;
277 		while (count > 0 && len > 0) {
278 			unsigned int _count;
279 			int nr_read;
280 
281 			_count = min3(count, len, PAGE_SIZE);
282 			nr_read = access_remote_vm(mm, p, page, _count, 0);
283 			if (nr_read < 0)
284 				rv = nr_read;
285 			if (nr_read <= 0)
286 				goto out_free_page;
287 
288 			if (copy_to_user(buf, page, nr_read)) {
289 				rv = -EFAULT;
290 				goto out_free_page;
291 			}
292 
293 			p	+= nr_read;
294 			len	-= nr_read;
295 			buf	+= nr_read;
296 			count	-= nr_read;
297 			rv	+= nr_read;
298 		}
299 	} else {
300 		/*
301 		 * Command line (1 string) occupies ARGV and
302 		 * extends into ENVP.
303 		 */
304 		struct {
305 			unsigned long p;
306 			unsigned long len;
307 		} cmdline[2] = {
308 			{ .p = arg_start, .len = len1 },
309 			{ .p = env_start, .len = len2 },
310 		};
311 		loff_t pos1 = *pos;
312 		unsigned int i;
313 
314 		i = 0;
315 		while (i < 2 && pos1 >= cmdline[i].len) {
316 			pos1 -= cmdline[i].len;
317 			i++;
318 		}
319 		while (i < 2) {
320 			p = cmdline[i].p + pos1;
321 			len = cmdline[i].len - pos1;
322 			while (count > 0 && len > 0) {
323 				unsigned int _count, l;
324 				int nr_read;
325 				bool final;
326 
327 				_count = min3(count, len, PAGE_SIZE);
328 				nr_read = access_remote_vm(mm, p, page, _count, 0);
329 				if (nr_read < 0)
330 					rv = nr_read;
331 				if (nr_read <= 0)
332 					goto out_free_page;
333 
334 				/*
335 				 * Command line can be shorter than whole ARGV
336 				 * even if last "marker" byte says it is not.
337 				 */
338 				final = false;
339 				l = strnlen(page, nr_read);
340 				if (l < nr_read) {
341 					nr_read = l;
342 					final = true;
343 				}
344 
345 				if (copy_to_user(buf, page, nr_read)) {
346 					rv = -EFAULT;
347 					goto out_free_page;
348 				}
349 
350 				p	+= nr_read;
351 				len	-= nr_read;
352 				buf	+= nr_read;
353 				count	-= nr_read;
354 				rv	+= nr_read;
355 
356 				if (final)
357 					goto out_free_page;
358 			}
359 
360 			/* Only first chunk can be read partially. */
361 			pos1 = 0;
362 			i++;
363 		}
364 	}
365 
366 out_free_page:
367 	free_page((unsigned long)page);
368 out_mmput:
369 	mmput(mm);
370 	if (rv > 0)
371 		*pos += rv;
372 	return rv;
373 }
374 
375 static const struct file_operations proc_pid_cmdline_ops = {
376 	.read	= proc_pid_cmdline_read,
377 	.llseek	= generic_file_llseek,
378 };
379 
380 #ifdef CONFIG_KALLSYMS
381 /*
382  * Provides a wchan file via kallsyms in a proper one-value-per-file format.
383  * Returns the resolved symbol.  If that fails, simply return the address.
384  */
385 static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns,
386 			  struct pid *pid, struct task_struct *task)
387 {
388 	unsigned long wchan;
389 	char symname[KSYM_NAME_LEN];
390 
391 	wchan = get_wchan(task);
392 
393 	if (wchan && ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)
394 			&& !lookup_symbol_name(wchan, symname))
395 		seq_printf(m, "%s", symname);
396 	else
397 		seq_putc(m, '0');
398 
399 	return 0;
400 }
401 #endif /* CONFIG_KALLSYMS */
402 
403 static int lock_trace(struct task_struct *task)
404 {
405 	int err = mutex_lock_killable(&task->signal->cred_guard_mutex);
406 	if (err)
407 		return err;
408 	if (!ptrace_may_access(task, PTRACE_MODE_ATTACH_FSCREDS)) {
409 		mutex_unlock(&task->signal->cred_guard_mutex);
410 		return -EPERM;
411 	}
412 	return 0;
413 }
414 
415 static void unlock_trace(struct task_struct *task)
416 {
417 	mutex_unlock(&task->signal->cred_guard_mutex);
418 }
419 
420 #ifdef CONFIG_STACKTRACE
421 
422 #define MAX_STACK_TRACE_DEPTH	64
423 
424 static int proc_pid_stack(struct seq_file *m, struct pid_namespace *ns,
425 			  struct pid *pid, struct task_struct *task)
426 {
427 	struct stack_trace trace;
428 	unsigned long *entries;
429 	int err;
430 	int i;
431 
432 	entries = kmalloc(MAX_STACK_TRACE_DEPTH * sizeof(*entries), GFP_KERNEL);
433 	if (!entries)
434 		return -ENOMEM;
435 
436 	trace.nr_entries	= 0;
437 	trace.max_entries	= MAX_STACK_TRACE_DEPTH;
438 	trace.entries		= entries;
439 	trace.skip		= 0;
440 
441 	err = lock_trace(task);
442 	if (!err) {
443 		save_stack_trace_tsk(task, &trace);
444 
445 		for (i = 0; i < trace.nr_entries; i++) {
446 			seq_printf(m, "[<0>] %pB\n", (void *)entries[i]);
447 		}
448 		unlock_trace(task);
449 	}
450 	kfree(entries);
451 
452 	return err;
453 }
454 #endif
455 
456 #ifdef CONFIG_SCHED_INFO
457 /*
458  * Provides /proc/PID/schedstat
459  */
460 static int proc_pid_schedstat(struct seq_file *m, struct pid_namespace *ns,
461 			      struct pid *pid, struct task_struct *task)
462 {
463 	if (unlikely(!sched_info_on()))
464 		seq_printf(m, "0 0 0\n");
465 	else
466 		seq_printf(m, "%llu %llu %lu\n",
467 		   (unsigned long long)task->se.sum_exec_runtime,
468 		   (unsigned long long)task->sched_info.run_delay,
469 		   task->sched_info.pcount);
470 
471 	return 0;
472 }
473 #endif
474 
475 #ifdef CONFIG_LATENCYTOP
476 static int lstats_show_proc(struct seq_file *m, void *v)
477 {
478 	int i;
479 	struct inode *inode = m->private;
480 	struct task_struct *task = get_proc_task(inode);
481 
482 	if (!task)
483 		return -ESRCH;
484 	seq_puts(m, "Latency Top version : v0.1\n");
485 	for (i = 0; i < 32; i++) {
486 		struct latency_record *lr = &task->latency_record[i];
487 		if (lr->backtrace[0]) {
488 			int q;
489 			seq_printf(m, "%i %li %li",
490 				   lr->count, lr->time, lr->max);
491 			for (q = 0; q < LT_BACKTRACEDEPTH; q++) {
492 				unsigned long bt = lr->backtrace[q];
493 				if (!bt)
494 					break;
495 				if (bt == ULONG_MAX)
496 					break;
497 				seq_printf(m, " %ps", (void *)bt);
498 			}
499 			seq_putc(m, '\n');
500 		}
501 
502 	}
503 	put_task_struct(task);
504 	return 0;
505 }
506 
507 static int lstats_open(struct inode *inode, struct file *file)
508 {
509 	return single_open(file, lstats_show_proc, inode);
510 }
511 
512 static ssize_t lstats_write(struct file *file, const char __user *buf,
513 			    size_t count, loff_t *offs)
514 {
515 	struct task_struct *task = get_proc_task(file_inode(file));
516 
517 	if (!task)
518 		return -ESRCH;
519 	clear_all_latency_tracing(task);
520 	put_task_struct(task);
521 
522 	return count;
523 }
524 
525 static const struct file_operations proc_lstats_operations = {
526 	.open		= lstats_open,
527 	.read		= seq_read,
528 	.write		= lstats_write,
529 	.llseek		= seq_lseek,
530 	.release	= single_release,
531 };
532 
533 #endif
534 
535 static int proc_oom_score(struct seq_file *m, struct pid_namespace *ns,
536 			  struct pid *pid, struct task_struct *task)
537 {
538 	unsigned long totalpages = totalram_pages + total_swap_pages;
539 	unsigned long points = 0;
540 
541 	points = oom_badness(task, NULL, NULL, totalpages) *
542 					1000 / totalpages;
543 	seq_printf(m, "%lu\n", points);
544 
545 	return 0;
546 }
547 
548 struct limit_names {
549 	const char *name;
550 	const char *unit;
551 };
552 
553 static const struct limit_names lnames[RLIM_NLIMITS] = {
554 	[RLIMIT_CPU] = {"Max cpu time", "seconds"},
555 	[RLIMIT_FSIZE] = {"Max file size", "bytes"},
556 	[RLIMIT_DATA] = {"Max data size", "bytes"},
557 	[RLIMIT_STACK] = {"Max stack size", "bytes"},
558 	[RLIMIT_CORE] = {"Max core file size", "bytes"},
559 	[RLIMIT_RSS] = {"Max resident set", "bytes"},
560 	[RLIMIT_NPROC] = {"Max processes", "processes"},
561 	[RLIMIT_NOFILE] = {"Max open files", "files"},
562 	[RLIMIT_MEMLOCK] = {"Max locked memory", "bytes"},
563 	[RLIMIT_AS] = {"Max address space", "bytes"},
564 	[RLIMIT_LOCKS] = {"Max file locks", "locks"},
565 	[RLIMIT_SIGPENDING] = {"Max pending signals", "signals"},
566 	[RLIMIT_MSGQUEUE] = {"Max msgqueue size", "bytes"},
567 	[RLIMIT_NICE] = {"Max nice priority", NULL},
568 	[RLIMIT_RTPRIO] = {"Max realtime priority", NULL},
569 	[RLIMIT_RTTIME] = {"Max realtime timeout", "us"},
570 };
571 
572 /* Display limits for a process */
573 static int proc_pid_limits(struct seq_file *m, struct pid_namespace *ns,
574 			   struct pid *pid, struct task_struct *task)
575 {
576 	unsigned int i;
577 	unsigned long flags;
578 
579 	struct rlimit rlim[RLIM_NLIMITS];
580 
581 	if (!lock_task_sighand(task, &flags))
582 		return 0;
583 	memcpy(rlim, task->signal->rlim, sizeof(struct rlimit) * RLIM_NLIMITS);
584 	unlock_task_sighand(task, &flags);
585 
586 	/*
587 	 * print the file header
588 	 */
589        seq_printf(m, "%-25s %-20s %-20s %-10s\n",
590 		  "Limit", "Soft Limit", "Hard Limit", "Units");
591 
592 	for (i = 0; i < RLIM_NLIMITS; i++) {
593 		if (rlim[i].rlim_cur == RLIM_INFINITY)
594 			seq_printf(m, "%-25s %-20s ",
595 				   lnames[i].name, "unlimited");
596 		else
597 			seq_printf(m, "%-25s %-20lu ",
598 				   lnames[i].name, rlim[i].rlim_cur);
599 
600 		if (rlim[i].rlim_max == RLIM_INFINITY)
601 			seq_printf(m, "%-20s ", "unlimited");
602 		else
603 			seq_printf(m, "%-20lu ", rlim[i].rlim_max);
604 
605 		if (lnames[i].unit)
606 			seq_printf(m, "%-10s\n", lnames[i].unit);
607 		else
608 			seq_putc(m, '\n');
609 	}
610 
611 	return 0;
612 }
613 
614 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
615 static int proc_pid_syscall(struct seq_file *m, struct pid_namespace *ns,
616 			    struct pid *pid, struct task_struct *task)
617 {
618 	long nr;
619 	unsigned long args[6], sp, pc;
620 	int res;
621 
622 	res = lock_trace(task);
623 	if (res)
624 		return res;
625 
626 	if (task_current_syscall(task, &nr, args, 6, &sp, &pc))
627 		seq_puts(m, "running\n");
628 	else if (nr < 0)
629 		seq_printf(m, "%ld 0x%lx 0x%lx\n", nr, sp, pc);
630 	else
631 		seq_printf(m,
632 		       "%ld 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx\n",
633 		       nr,
634 		       args[0], args[1], args[2], args[3], args[4], args[5],
635 		       sp, pc);
636 	unlock_trace(task);
637 
638 	return 0;
639 }
640 #endif /* CONFIG_HAVE_ARCH_TRACEHOOK */
641 
642 /************************************************************************/
643 /*                       Here the fs part begins                        */
644 /************************************************************************/
645 
646 /* permission checks */
647 static int proc_fd_access_allowed(struct inode *inode)
648 {
649 	struct task_struct *task;
650 	int allowed = 0;
651 	/* Allow access to a task's file descriptors if it is us or we
652 	 * may use ptrace attach to the process and find out that
653 	 * information.
654 	 */
655 	task = get_proc_task(inode);
656 	if (task) {
657 		allowed = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
658 		put_task_struct(task);
659 	}
660 	return allowed;
661 }
662 
663 int proc_setattr(struct dentry *dentry, struct iattr *attr)
664 {
665 	int error;
666 	struct inode *inode = d_inode(dentry);
667 
668 	if (attr->ia_valid & ATTR_MODE)
669 		return -EPERM;
670 
671 	error = setattr_prepare(dentry, attr);
672 	if (error)
673 		return error;
674 
675 	setattr_copy(inode, attr);
676 	mark_inode_dirty(inode);
677 	return 0;
678 }
679 
680 /*
681  * May current process learn task's sched/cmdline info (for hide_pid_min=1)
682  * or euid/egid (for hide_pid_min=2)?
683  */
684 static bool has_pid_permissions(struct pid_namespace *pid,
685 				 struct task_struct *task,
686 				 int hide_pid_min)
687 {
688 	if (pid->hide_pid < hide_pid_min)
689 		return true;
690 	if (in_group_p(pid->pid_gid))
691 		return true;
692 	return ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
693 }
694 
695 
696 static int proc_pid_permission(struct inode *inode, int mask)
697 {
698 	struct pid_namespace *pid = inode->i_sb->s_fs_info;
699 	struct task_struct *task;
700 	bool has_perms;
701 
702 	task = get_proc_task(inode);
703 	if (!task)
704 		return -ESRCH;
705 	has_perms = has_pid_permissions(pid, task, HIDEPID_NO_ACCESS);
706 	put_task_struct(task);
707 
708 	if (!has_perms) {
709 		if (pid->hide_pid == HIDEPID_INVISIBLE) {
710 			/*
711 			 * Let's make getdents(), stat(), and open()
712 			 * consistent with each other.  If a process
713 			 * may not stat() a file, it shouldn't be seen
714 			 * in procfs at all.
715 			 */
716 			return -ENOENT;
717 		}
718 
719 		return -EPERM;
720 	}
721 	return generic_permission(inode, mask);
722 }
723 
724 
725 
726 static const struct inode_operations proc_def_inode_operations = {
727 	.setattr	= proc_setattr,
728 };
729 
730 static int proc_single_show(struct seq_file *m, void *v)
731 {
732 	struct inode *inode = m->private;
733 	struct pid_namespace *ns;
734 	struct pid *pid;
735 	struct task_struct *task;
736 	int ret;
737 
738 	ns = inode->i_sb->s_fs_info;
739 	pid = proc_pid(inode);
740 	task = get_pid_task(pid, PIDTYPE_PID);
741 	if (!task)
742 		return -ESRCH;
743 
744 	ret = PROC_I(inode)->op.proc_show(m, ns, pid, task);
745 
746 	put_task_struct(task);
747 	return ret;
748 }
749 
750 static int proc_single_open(struct inode *inode, struct file *filp)
751 {
752 	return single_open(filp, proc_single_show, inode);
753 }
754 
755 static const struct file_operations proc_single_file_operations = {
756 	.open		= proc_single_open,
757 	.read		= seq_read,
758 	.llseek		= seq_lseek,
759 	.release	= single_release,
760 };
761 
762 
763 struct mm_struct *proc_mem_open(struct inode *inode, unsigned int mode)
764 {
765 	struct task_struct *task = get_proc_task(inode);
766 	struct mm_struct *mm = ERR_PTR(-ESRCH);
767 
768 	if (task) {
769 		mm = mm_access(task, mode | PTRACE_MODE_FSCREDS);
770 		put_task_struct(task);
771 
772 		if (!IS_ERR_OR_NULL(mm)) {
773 			/* ensure this mm_struct can't be freed */
774 			mmgrab(mm);
775 			/* but do not pin its memory */
776 			mmput(mm);
777 		}
778 	}
779 
780 	return mm;
781 }
782 
783 static int __mem_open(struct inode *inode, struct file *file, unsigned int mode)
784 {
785 	struct mm_struct *mm = proc_mem_open(inode, mode);
786 
787 	if (IS_ERR(mm))
788 		return PTR_ERR(mm);
789 
790 	file->private_data = mm;
791 	return 0;
792 }
793 
794 static int mem_open(struct inode *inode, struct file *file)
795 {
796 	int ret = __mem_open(inode, file, PTRACE_MODE_ATTACH);
797 
798 	/* OK to pass negative loff_t, we can catch out-of-range */
799 	file->f_mode |= FMODE_UNSIGNED_OFFSET;
800 
801 	return ret;
802 }
803 
804 static ssize_t mem_rw(struct file *file, char __user *buf,
805 			size_t count, loff_t *ppos, int write)
806 {
807 	struct mm_struct *mm = file->private_data;
808 	unsigned long addr = *ppos;
809 	ssize_t copied;
810 	char *page;
811 	unsigned int flags;
812 
813 	if (!mm)
814 		return 0;
815 
816 	page = (char *)__get_free_page(GFP_KERNEL);
817 	if (!page)
818 		return -ENOMEM;
819 
820 	copied = 0;
821 	if (!mmget_not_zero(mm))
822 		goto free;
823 
824 	flags = FOLL_FORCE | (write ? FOLL_WRITE : 0);
825 
826 	while (count > 0) {
827 		int this_len = min_t(int, count, PAGE_SIZE);
828 
829 		if (write && copy_from_user(page, buf, this_len)) {
830 			copied = -EFAULT;
831 			break;
832 		}
833 
834 		this_len = access_remote_vm(mm, addr, page, this_len, flags);
835 		if (!this_len) {
836 			if (!copied)
837 				copied = -EIO;
838 			break;
839 		}
840 
841 		if (!write && copy_to_user(buf, page, this_len)) {
842 			copied = -EFAULT;
843 			break;
844 		}
845 
846 		buf += this_len;
847 		addr += this_len;
848 		copied += this_len;
849 		count -= this_len;
850 	}
851 	*ppos = addr;
852 
853 	mmput(mm);
854 free:
855 	free_page((unsigned long) page);
856 	return copied;
857 }
858 
859 static ssize_t mem_read(struct file *file, char __user *buf,
860 			size_t count, loff_t *ppos)
861 {
862 	return mem_rw(file, buf, count, ppos, 0);
863 }
864 
865 static ssize_t mem_write(struct file *file, const char __user *buf,
866 			 size_t count, loff_t *ppos)
867 {
868 	return mem_rw(file, (char __user*)buf, count, ppos, 1);
869 }
870 
871 loff_t mem_lseek(struct file *file, loff_t offset, int orig)
872 {
873 	switch (orig) {
874 	case 0:
875 		file->f_pos = offset;
876 		break;
877 	case 1:
878 		file->f_pos += offset;
879 		break;
880 	default:
881 		return -EINVAL;
882 	}
883 	force_successful_syscall_return();
884 	return file->f_pos;
885 }
886 
887 static int mem_release(struct inode *inode, struct file *file)
888 {
889 	struct mm_struct *mm = file->private_data;
890 	if (mm)
891 		mmdrop(mm);
892 	return 0;
893 }
894 
895 static const struct file_operations proc_mem_operations = {
896 	.llseek		= mem_lseek,
897 	.read		= mem_read,
898 	.write		= mem_write,
899 	.open		= mem_open,
900 	.release	= mem_release,
901 };
902 
903 static int environ_open(struct inode *inode, struct file *file)
904 {
905 	return __mem_open(inode, file, PTRACE_MODE_READ);
906 }
907 
908 static ssize_t environ_read(struct file *file, char __user *buf,
909 			size_t count, loff_t *ppos)
910 {
911 	char *page;
912 	unsigned long src = *ppos;
913 	int ret = 0;
914 	struct mm_struct *mm = file->private_data;
915 	unsigned long env_start, env_end;
916 
917 	/* Ensure the process spawned far enough to have an environment. */
918 	if (!mm || !mm->env_end)
919 		return 0;
920 
921 	page = (char *)__get_free_page(GFP_KERNEL);
922 	if (!page)
923 		return -ENOMEM;
924 
925 	ret = 0;
926 	if (!mmget_not_zero(mm))
927 		goto free;
928 
929 	down_read(&mm->mmap_sem);
930 	env_start = mm->env_start;
931 	env_end = mm->env_end;
932 	up_read(&mm->mmap_sem);
933 
934 	while (count > 0) {
935 		size_t this_len, max_len;
936 		int retval;
937 
938 		if (src >= (env_end - env_start))
939 			break;
940 
941 		this_len = env_end - (env_start + src);
942 
943 		max_len = min_t(size_t, PAGE_SIZE, count);
944 		this_len = min(max_len, this_len);
945 
946 		retval = access_remote_vm(mm, (env_start + src), page, this_len, 0);
947 
948 		if (retval <= 0) {
949 			ret = retval;
950 			break;
951 		}
952 
953 		if (copy_to_user(buf, page, retval)) {
954 			ret = -EFAULT;
955 			break;
956 		}
957 
958 		ret += retval;
959 		src += retval;
960 		buf += retval;
961 		count -= retval;
962 	}
963 	*ppos = src;
964 	mmput(mm);
965 
966 free:
967 	free_page((unsigned long) page);
968 	return ret;
969 }
970 
971 static const struct file_operations proc_environ_operations = {
972 	.open		= environ_open,
973 	.read		= environ_read,
974 	.llseek		= generic_file_llseek,
975 	.release	= mem_release,
976 };
977 
978 static int auxv_open(struct inode *inode, struct file *file)
979 {
980 	return __mem_open(inode, file, PTRACE_MODE_READ_FSCREDS);
981 }
982 
983 static ssize_t auxv_read(struct file *file, char __user *buf,
984 			size_t count, loff_t *ppos)
985 {
986 	struct mm_struct *mm = file->private_data;
987 	unsigned int nwords = 0;
988 
989 	if (!mm)
990 		return 0;
991 	do {
992 		nwords += 2;
993 	} while (mm->saved_auxv[nwords - 2] != 0); /* AT_NULL */
994 	return simple_read_from_buffer(buf, count, ppos, mm->saved_auxv,
995 				       nwords * sizeof(mm->saved_auxv[0]));
996 }
997 
998 static const struct file_operations proc_auxv_operations = {
999 	.open		= auxv_open,
1000 	.read		= auxv_read,
1001 	.llseek		= generic_file_llseek,
1002 	.release	= mem_release,
1003 };
1004 
1005 static ssize_t oom_adj_read(struct file *file, char __user *buf, size_t count,
1006 			    loff_t *ppos)
1007 {
1008 	struct task_struct *task = get_proc_task(file_inode(file));
1009 	char buffer[PROC_NUMBUF];
1010 	int oom_adj = OOM_ADJUST_MIN;
1011 	size_t len;
1012 
1013 	if (!task)
1014 		return -ESRCH;
1015 	if (task->signal->oom_score_adj == OOM_SCORE_ADJ_MAX)
1016 		oom_adj = OOM_ADJUST_MAX;
1017 	else
1018 		oom_adj = (task->signal->oom_score_adj * -OOM_DISABLE) /
1019 			  OOM_SCORE_ADJ_MAX;
1020 	put_task_struct(task);
1021 	len = snprintf(buffer, sizeof(buffer), "%d\n", oom_adj);
1022 	return simple_read_from_buffer(buf, count, ppos, buffer, len);
1023 }
1024 
1025 static int __set_oom_adj(struct file *file, int oom_adj, bool legacy)
1026 {
1027 	static DEFINE_MUTEX(oom_adj_mutex);
1028 	struct mm_struct *mm = NULL;
1029 	struct task_struct *task;
1030 	int err = 0;
1031 
1032 	task = get_proc_task(file_inode(file));
1033 	if (!task)
1034 		return -ESRCH;
1035 
1036 	mutex_lock(&oom_adj_mutex);
1037 	if (legacy) {
1038 		if (oom_adj < task->signal->oom_score_adj &&
1039 				!capable(CAP_SYS_RESOURCE)) {
1040 			err = -EACCES;
1041 			goto err_unlock;
1042 		}
1043 		/*
1044 		 * /proc/pid/oom_adj is provided for legacy purposes, ask users to use
1045 		 * /proc/pid/oom_score_adj instead.
1046 		 */
1047 		pr_warn_once("%s (%d): /proc/%d/oom_adj is deprecated, please use /proc/%d/oom_score_adj instead.\n",
1048 			  current->comm, task_pid_nr(current), task_pid_nr(task),
1049 			  task_pid_nr(task));
1050 	} else {
1051 		if ((short)oom_adj < task->signal->oom_score_adj_min &&
1052 				!capable(CAP_SYS_RESOURCE)) {
1053 			err = -EACCES;
1054 			goto err_unlock;
1055 		}
1056 	}
1057 
1058 	/*
1059 	 * Make sure we will check other processes sharing the mm if this is
1060 	 * not vfrok which wants its own oom_score_adj.
1061 	 * pin the mm so it doesn't go away and get reused after task_unlock
1062 	 */
1063 	if (!task->vfork_done) {
1064 		struct task_struct *p = find_lock_task_mm(task);
1065 
1066 		if (p) {
1067 			if (atomic_read(&p->mm->mm_users) > 1) {
1068 				mm = p->mm;
1069 				mmgrab(mm);
1070 			}
1071 			task_unlock(p);
1072 		}
1073 	}
1074 
1075 	task->signal->oom_score_adj = oom_adj;
1076 	if (!legacy && has_capability_noaudit(current, CAP_SYS_RESOURCE))
1077 		task->signal->oom_score_adj_min = (short)oom_adj;
1078 	trace_oom_score_adj_update(task);
1079 
1080 	if (mm) {
1081 		struct task_struct *p;
1082 
1083 		rcu_read_lock();
1084 		for_each_process(p) {
1085 			if (same_thread_group(task, p))
1086 				continue;
1087 
1088 			/* do not touch kernel threads or the global init */
1089 			if (p->flags & PF_KTHREAD || is_global_init(p))
1090 				continue;
1091 
1092 			task_lock(p);
1093 			if (!p->vfork_done && process_shares_mm(p, mm)) {
1094 				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",
1095 						task_pid_nr(p), p->comm,
1096 						p->signal->oom_score_adj, oom_adj,
1097 						task_pid_nr(task), task->comm);
1098 				p->signal->oom_score_adj = oom_adj;
1099 				if (!legacy && has_capability_noaudit(current, CAP_SYS_RESOURCE))
1100 					p->signal->oom_score_adj_min = (short)oom_adj;
1101 			}
1102 			task_unlock(p);
1103 		}
1104 		rcu_read_unlock();
1105 		mmdrop(mm);
1106 	}
1107 err_unlock:
1108 	mutex_unlock(&oom_adj_mutex);
1109 	put_task_struct(task);
1110 	return err;
1111 }
1112 
1113 /*
1114  * /proc/pid/oom_adj exists solely for backwards compatibility with previous
1115  * kernels.  The effective policy is defined by oom_score_adj, which has a
1116  * different scale: oom_adj grew exponentially and oom_score_adj grows linearly.
1117  * Values written to oom_adj are simply mapped linearly to oom_score_adj.
1118  * Processes that become oom disabled via oom_adj will still be oom disabled
1119  * with this implementation.
1120  *
1121  * oom_adj cannot be removed since existing userspace binaries use it.
1122  */
1123 static ssize_t oom_adj_write(struct file *file, const char __user *buf,
1124 			     size_t count, loff_t *ppos)
1125 {
1126 	char buffer[PROC_NUMBUF];
1127 	int oom_adj;
1128 	int err;
1129 
1130 	memset(buffer, 0, sizeof(buffer));
1131 	if (count > sizeof(buffer) - 1)
1132 		count = sizeof(buffer) - 1;
1133 	if (copy_from_user(buffer, buf, count)) {
1134 		err = -EFAULT;
1135 		goto out;
1136 	}
1137 
1138 	err = kstrtoint(strstrip(buffer), 0, &oom_adj);
1139 	if (err)
1140 		goto out;
1141 	if ((oom_adj < OOM_ADJUST_MIN || oom_adj > OOM_ADJUST_MAX) &&
1142 	     oom_adj != OOM_DISABLE) {
1143 		err = -EINVAL;
1144 		goto out;
1145 	}
1146 
1147 	/*
1148 	 * Scale /proc/pid/oom_score_adj appropriately ensuring that a maximum
1149 	 * value is always attainable.
1150 	 */
1151 	if (oom_adj == OOM_ADJUST_MAX)
1152 		oom_adj = OOM_SCORE_ADJ_MAX;
1153 	else
1154 		oom_adj = (oom_adj * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE;
1155 
1156 	err = __set_oom_adj(file, oom_adj, true);
1157 out:
1158 	return err < 0 ? err : count;
1159 }
1160 
1161 static const struct file_operations proc_oom_adj_operations = {
1162 	.read		= oom_adj_read,
1163 	.write		= oom_adj_write,
1164 	.llseek		= generic_file_llseek,
1165 };
1166 
1167 static ssize_t oom_score_adj_read(struct file *file, char __user *buf,
1168 					size_t count, loff_t *ppos)
1169 {
1170 	struct task_struct *task = get_proc_task(file_inode(file));
1171 	char buffer[PROC_NUMBUF];
1172 	short oom_score_adj = OOM_SCORE_ADJ_MIN;
1173 	size_t len;
1174 
1175 	if (!task)
1176 		return -ESRCH;
1177 	oom_score_adj = task->signal->oom_score_adj;
1178 	put_task_struct(task);
1179 	len = snprintf(buffer, sizeof(buffer), "%hd\n", oom_score_adj);
1180 	return simple_read_from_buffer(buf, count, ppos, buffer, len);
1181 }
1182 
1183 static ssize_t oom_score_adj_write(struct file *file, const char __user *buf,
1184 					size_t count, loff_t *ppos)
1185 {
1186 	char buffer[PROC_NUMBUF];
1187 	int oom_score_adj;
1188 	int err;
1189 
1190 	memset(buffer, 0, sizeof(buffer));
1191 	if (count > sizeof(buffer) - 1)
1192 		count = sizeof(buffer) - 1;
1193 	if (copy_from_user(buffer, buf, count)) {
1194 		err = -EFAULT;
1195 		goto out;
1196 	}
1197 
1198 	err = kstrtoint(strstrip(buffer), 0, &oom_score_adj);
1199 	if (err)
1200 		goto out;
1201 	if (oom_score_adj < OOM_SCORE_ADJ_MIN ||
1202 			oom_score_adj > OOM_SCORE_ADJ_MAX) {
1203 		err = -EINVAL;
1204 		goto out;
1205 	}
1206 
1207 	err = __set_oom_adj(file, oom_score_adj, false);
1208 out:
1209 	return err < 0 ? err : count;
1210 }
1211 
1212 static const struct file_operations proc_oom_score_adj_operations = {
1213 	.read		= oom_score_adj_read,
1214 	.write		= oom_score_adj_write,
1215 	.llseek		= default_llseek,
1216 };
1217 
1218 #ifdef CONFIG_AUDITSYSCALL
1219 #define TMPBUFLEN 11
1220 static ssize_t proc_loginuid_read(struct file * file, char __user * buf,
1221 				  size_t count, loff_t *ppos)
1222 {
1223 	struct inode * inode = file_inode(file);
1224 	struct task_struct *task = get_proc_task(inode);
1225 	ssize_t length;
1226 	char tmpbuf[TMPBUFLEN];
1227 
1228 	if (!task)
1229 		return -ESRCH;
1230 	length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
1231 			   from_kuid(file->f_cred->user_ns,
1232 				     audit_get_loginuid(task)));
1233 	put_task_struct(task);
1234 	return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
1235 }
1236 
1237 static ssize_t proc_loginuid_write(struct file * file, const char __user * buf,
1238 				   size_t count, loff_t *ppos)
1239 {
1240 	struct inode * inode = file_inode(file);
1241 	uid_t loginuid;
1242 	kuid_t kloginuid;
1243 	int rv;
1244 
1245 	rcu_read_lock();
1246 	if (current != pid_task(proc_pid(inode), PIDTYPE_PID)) {
1247 		rcu_read_unlock();
1248 		return -EPERM;
1249 	}
1250 	rcu_read_unlock();
1251 
1252 	if (*ppos != 0) {
1253 		/* No partial writes. */
1254 		return -EINVAL;
1255 	}
1256 
1257 	rv = kstrtou32_from_user(buf, count, 10, &loginuid);
1258 	if (rv < 0)
1259 		return rv;
1260 
1261 	/* is userspace tring to explicitly UNSET the loginuid? */
1262 	if (loginuid == AUDIT_UID_UNSET) {
1263 		kloginuid = INVALID_UID;
1264 	} else {
1265 		kloginuid = make_kuid(file->f_cred->user_ns, loginuid);
1266 		if (!uid_valid(kloginuid))
1267 			return -EINVAL;
1268 	}
1269 
1270 	rv = audit_set_loginuid(kloginuid);
1271 	if (rv < 0)
1272 		return rv;
1273 	return count;
1274 }
1275 
1276 static const struct file_operations proc_loginuid_operations = {
1277 	.read		= proc_loginuid_read,
1278 	.write		= proc_loginuid_write,
1279 	.llseek		= generic_file_llseek,
1280 };
1281 
1282 static ssize_t proc_sessionid_read(struct file * file, char __user * buf,
1283 				  size_t count, loff_t *ppos)
1284 {
1285 	struct inode * inode = file_inode(file);
1286 	struct task_struct *task = get_proc_task(inode);
1287 	ssize_t length;
1288 	char tmpbuf[TMPBUFLEN];
1289 
1290 	if (!task)
1291 		return -ESRCH;
1292 	length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
1293 				audit_get_sessionid(task));
1294 	put_task_struct(task);
1295 	return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
1296 }
1297 
1298 static const struct file_operations proc_sessionid_operations = {
1299 	.read		= proc_sessionid_read,
1300 	.llseek		= generic_file_llseek,
1301 };
1302 #endif
1303 
1304 #ifdef CONFIG_FAULT_INJECTION
1305 static ssize_t proc_fault_inject_read(struct file * file, char __user * buf,
1306 				      size_t count, loff_t *ppos)
1307 {
1308 	struct task_struct *task = get_proc_task(file_inode(file));
1309 	char buffer[PROC_NUMBUF];
1310 	size_t len;
1311 	int make_it_fail;
1312 
1313 	if (!task)
1314 		return -ESRCH;
1315 	make_it_fail = task->make_it_fail;
1316 	put_task_struct(task);
1317 
1318 	len = snprintf(buffer, sizeof(buffer), "%i\n", make_it_fail);
1319 
1320 	return simple_read_from_buffer(buf, count, ppos, buffer, len);
1321 }
1322 
1323 static ssize_t proc_fault_inject_write(struct file * file,
1324 			const char __user * buf, size_t count, loff_t *ppos)
1325 {
1326 	struct task_struct *task;
1327 	char buffer[PROC_NUMBUF];
1328 	int make_it_fail;
1329 	int rv;
1330 
1331 	if (!capable(CAP_SYS_RESOURCE))
1332 		return -EPERM;
1333 	memset(buffer, 0, sizeof(buffer));
1334 	if (count > sizeof(buffer) - 1)
1335 		count = sizeof(buffer) - 1;
1336 	if (copy_from_user(buffer, buf, count))
1337 		return -EFAULT;
1338 	rv = kstrtoint(strstrip(buffer), 0, &make_it_fail);
1339 	if (rv < 0)
1340 		return rv;
1341 	if (make_it_fail < 0 || make_it_fail > 1)
1342 		return -EINVAL;
1343 
1344 	task = get_proc_task(file_inode(file));
1345 	if (!task)
1346 		return -ESRCH;
1347 	task->make_it_fail = make_it_fail;
1348 	put_task_struct(task);
1349 
1350 	return count;
1351 }
1352 
1353 static const struct file_operations proc_fault_inject_operations = {
1354 	.read		= proc_fault_inject_read,
1355 	.write		= proc_fault_inject_write,
1356 	.llseek		= generic_file_llseek,
1357 };
1358 
1359 static ssize_t proc_fail_nth_write(struct file *file, const char __user *buf,
1360 				   size_t count, loff_t *ppos)
1361 {
1362 	struct task_struct *task;
1363 	int err;
1364 	unsigned int n;
1365 
1366 	err = kstrtouint_from_user(buf, count, 0, &n);
1367 	if (err)
1368 		return err;
1369 
1370 	task = get_proc_task(file_inode(file));
1371 	if (!task)
1372 		return -ESRCH;
1373 	WRITE_ONCE(task->fail_nth, n);
1374 	put_task_struct(task);
1375 
1376 	return count;
1377 }
1378 
1379 static ssize_t proc_fail_nth_read(struct file *file, char __user *buf,
1380 				  size_t count, loff_t *ppos)
1381 {
1382 	struct task_struct *task;
1383 	char numbuf[PROC_NUMBUF];
1384 	ssize_t len;
1385 
1386 	task = get_proc_task(file_inode(file));
1387 	if (!task)
1388 		return -ESRCH;
1389 	len = snprintf(numbuf, sizeof(numbuf), "%u\n",
1390 			READ_ONCE(task->fail_nth));
1391 	len = simple_read_from_buffer(buf, count, ppos, numbuf, len);
1392 	put_task_struct(task);
1393 
1394 	return len;
1395 }
1396 
1397 static const struct file_operations proc_fail_nth_operations = {
1398 	.read		= proc_fail_nth_read,
1399 	.write		= proc_fail_nth_write,
1400 };
1401 #endif
1402 
1403 
1404 #ifdef CONFIG_SCHED_DEBUG
1405 /*
1406  * Print out various scheduling related per-task fields:
1407  */
1408 static int sched_show(struct seq_file *m, void *v)
1409 {
1410 	struct inode *inode = m->private;
1411 	struct pid_namespace *ns = inode->i_sb->s_fs_info;
1412 	struct task_struct *p;
1413 
1414 	p = get_proc_task(inode);
1415 	if (!p)
1416 		return -ESRCH;
1417 	proc_sched_show_task(p, ns, m);
1418 
1419 	put_task_struct(p);
1420 
1421 	return 0;
1422 }
1423 
1424 static ssize_t
1425 sched_write(struct file *file, const char __user *buf,
1426 	    size_t count, loff_t *offset)
1427 {
1428 	struct inode *inode = file_inode(file);
1429 	struct task_struct *p;
1430 
1431 	p = get_proc_task(inode);
1432 	if (!p)
1433 		return -ESRCH;
1434 	proc_sched_set_task(p);
1435 
1436 	put_task_struct(p);
1437 
1438 	return count;
1439 }
1440 
1441 static int sched_open(struct inode *inode, struct file *filp)
1442 {
1443 	return single_open(filp, sched_show, inode);
1444 }
1445 
1446 static const struct file_operations proc_pid_sched_operations = {
1447 	.open		= sched_open,
1448 	.read		= seq_read,
1449 	.write		= sched_write,
1450 	.llseek		= seq_lseek,
1451 	.release	= single_release,
1452 };
1453 
1454 #endif
1455 
1456 #ifdef CONFIG_SCHED_AUTOGROUP
1457 /*
1458  * Print out autogroup related information:
1459  */
1460 static int sched_autogroup_show(struct seq_file *m, void *v)
1461 {
1462 	struct inode *inode = m->private;
1463 	struct task_struct *p;
1464 
1465 	p = get_proc_task(inode);
1466 	if (!p)
1467 		return -ESRCH;
1468 	proc_sched_autogroup_show_task(p, m);
1469 
1470 	put_task_struct(p);
1471 
1472 	return 0;
1473 }
1474 
1475 static ssize_t
1476 sched_autogroup_write(struct file *file, const char __user *buf,
1477 	    size_t count, loff_t *offset)
1478 {
1479 	struct inode *inode = file_inode(file);
1480 	struct task_struct *p;
1481 	char buffer[PROC_NUMBUF];
1482 	int nice;
1483 	int err;
1484 
1485 	memset(buffer, 0, sizeof(buffer));
1486 	if (count > sizeof(buffer) - 1)
1487 		count = sizeof(buffer) - 1;
1488 	if (copy_from_user(buffer, buf, count))
1489 		return -EFAULT;
1490 
1491 	err = kstrtoint(strstrip(buffer), 0, &nice);
1492 	if (err < 0)
1493 		return err;
1494 
1495 	p = get_proc_task(inode);
1496 	if (!p)
1497 		return -ESRCH;
1498 
1499 	err = proc_sched_autogroup_set_nice(p, nice);
1500 	if (err)
1501 		count = err;
1502 
1503 	put_task_struct(p);
1504 
1505 	return count;
1506 }
1507 
1508 static int sched_autogroup_open(struct inode *inode, struct file *filp)
1509 {
1510 	int ret;
1511 
1512 	ret = single_open(filp, sched_autogroup_show, NULL);
1513 	if (!ret) {
1514 		struct seq_file *m = filp->private_data;
1515 
1516 		m->private = inode;
1517 	}
1518 	return ret;
1519 }
1520 
1521 static const struct file_operations proc_pid_sched_autogroup_operations = {
1522 	.open		= sched_autogroup_open,
1523 	.read		= seq_read,
1524 	.write		= sched_autogroup_write,
1525 	.llseek		= seq_lseek,
1526 	.release	= single_release,
1527 };
1528 
1529 #endif /* CONFIG_SCHED_AUTOGROUP */
1530 
1531 static ssize_t comm_write(struct file *file, const char __user *buf,
1532 				size_t count, loff_t *offset)
1533 {
1534 	struct inode *inode = file_inode(file);
1535 	struct task_struct *p;
1536 	char buffer[TASK_COMM_LEN];
1537 	const size_t maxlen = sizeof(buffer) - 1;
1538 
1539 	memset(buffer, 0, sizeof(buffer));
1540 	if (copy_from_user(buffer, buf, count > maxlen ? maxlen : count))
1541 		return -EFAULT;
1542 
1543 	p = get_proc_task(inode);
1544 	if (!p)
1545 		return -ESRCH;
1546 
1547 	if (same_thread_group(current, p))
1548 		set_task_comm(p, buffer);
1549 	else
1550 		count = -EINVAL;
1551 
1552 	put_task_struct(p);
1553 
1554 	return count;
1555 }
1556 
1557 static int comm_show(struct seq_file *m, void *v)
1558 {
1559 	struct inode *inode = m->private;
1560 	struct task_struct *p;
1561 
1562 	p = get_proc_task(inode);
1563 	if (!p)
1564 		return -ESRCH;
1565 
1566 	task_lock(p);
1567 	seq_printf(m, "%s\n", p->comm);
1568 	task_unlock(p);
1569 
1570 	put_task_struct(p);
1571 
1572 	return 0;
1573 }
1574 
1575 static int comm_open(struct inode *inode, struct file *filp)
1576 {
1577 	return single_open(filp, comm_show, inode);
1578 }
1579 
1580 static const struct file_operations proc_pid_set_comm_operations = {
1581 	.open		= comm_open,
1582 	.read		= seq_read,
1583 	.write		= comm_write,
1584 	.llseek		= seq_lseek,
1585 	.release	= single_release,
1586 };
1587 
1588 static int proc_exe_link(struct dentry *dentry, struct path *exe_path)
1589 {
1590 	struct task_struct *task;
1591 	struct file *exe_file;
1592 
1593 	task = get_proc_task(d_inode(dentry));
1594 	if (!task)
1595 		return -ENOENT;
1596 	exe_file = get_task_exe_file(task);
1597 	put_task_struct(task);
1598 	if (exe_file) {
1599 		*exe_path = exe_file->f_path;
1600 		path_get(&exe_file->f_path);
1601 		fput(exe_file);
1602 		return 0;
1603 	} else
1604 		return -ENOENT;
1605 }
1606 
1607 static const char *proc_pid_get_link(struct dentry *dentry,
1608 				     struct inode *inode,
1609 				     struct delayed_call *done)
1610 {
1611 	struct path path;
1612 	int error = -EACCES;
1613 
1614 	if (!dentry)
1615 		return ERR_PTR(-ECHILD);
1616 
1617 	/* Are we allowed to snoop on the tasks file descriptors? */
1618 	if (!proc_fd_access_allowed(inode))
1619 		goto out;
1620 
1621 	error = PROC_I(inode)->op.proc_get_link(dentry, &path);
1622 	if (error)
1623 		goto out;
1624 
1625 	nd_jump_link(&path);
1626 	return NULL;
1627 out:
1628 	return ERR_PTR(error);
1629 }
1630 
1631 static int do_proc_readlink(struct path *path, char __user *buffer, int buflen)
1632 {
1633 	char *tmp = (char *)__get_free_page(GFP_KERNEL);
1634 	char *pathname;
1635 	int len;
1636 
1637 	if (!tmp)
1638 		return -ENOMEM;
1639 
1640 	pathname = d_path(path, tmp, PAGE_SIZE);
1641 	len = PTR_ERR(pathname);
1642 	if (IS_ERR(pathname))
1643 		goto out;
1644 	len = tmp + PAGE_SIZE - 1 - pathname;
1645 
1646 	if (len > buflen)
1647 		len = buflen;
1648 	if (copy_to_user(buffer, pathname, len))
1649 		len = -EFAULT;
1650  out:
1651 	free_page((unsigned long)tmp);
1652 	return len;
1653 }
1654 
1655 static int proc_pid_readlink(struct dentry * dentry, char __user * buffer, int buflen)
1656 {
1657 	int error = -EACCES;
1658 	struct inode *inode = d_inode(dentry);
1659 	struct path path;
1660 
1661 	/* Are we allowed to snoop on the tasks file descriptors? */
1662 	if (!proc_fd_access_allowed(inode))
1663 		goto out;
1664 
1665 	error = PROC_I(inode)->op.proc_get_link(dentry, &path);
1666 	if (error)
1667 		goto out;
1668 
1669 	error = do_proc_readlink(&path, buffer, buflen);
1670 	path_put(&path);
1671 out:
1672 	return error;
1673 }
1674 
1675 const struct inode_operations proc_pid_link_inode_operations = {
1676 	.readlink	= proc_pid_readlink,
1677 	.get_link	= proc_pid_get_link,
1678 	.setattr	= proc_setattr,
1679 };
1680 
1681 
1682 /* building an inode */
1683 
1684 void task_dump_owner(struct task_struct *task, umode_t mode,
1685 		     kuid_t *ruid, kgid_t *rgid)
1686 {
1687 	/* Depending on the state of dumpable compute who should own a
1688 	 * proc file for a task.
1689 	 */
1690 	const struct cred *cred;
1691 	kuid_t uid;
1692 	kgid_t gid;
1693 
1694 	/* Default to the tasks effective ownership */
1695 	rcu_read_lock();
1696 	cred = __task_cred(task);
1697 	uid = cred->euid;
1698 	gid = cred->egid;
1699 	rcu_read_unlock();
1700 
1701 	/*
1702 	 * Before the /proc/pid/status file was created the only way to read
1703 	 * the effective uid of a /process was to stat /proc/pid.  Reading
1704 	 * /proc/pid/status is slow enough that procps and other packages
1705 	 * kept stating /proc/pid.  To keep the rules in /proc simple I have
1706 	 * made this apply to all per process world readable and executable
1707 	 * directories.
1708 	 */
1709 	if (mode != (S_IFDIR|S_IRUGO|S_IXUGO)) {
1710 		struct mm_struct *mm;
1711 		task_lock(task);
1712 		mm = task->mm;
1713 		/* Make non-dumpable tasks owned by some root */
1714 		if (mm) {
1715 			if (get_dumpable(mm) != SUID_DUMP_USER) {
1716 				struct user_namespace *user_ns = mm->user_ns;
1717 
1718 				uid = make_kuid(user_ns, 0);
1719 				if (!uid_valid(uid))
1720 					uid = GLOBAL_ROOT_UID;
1721 
1722 				gid = make_kgid(user_ns, 0);
1723 				if (!gid_valid(gid))
1724 					gid = GLOBAL_ROOT_GID;
1725 			}
1726 		} else {
1727 			uid = GLOBAL_ROOT_UID;
1728 			gid = GLOBAL_ROOT_GID;
1729 		}
1730 		task_unlock(task);
1731 	}
1732 	*ruid = uid;
1733 	*rgid = gid;
1734 }
1735 
1736 struct inode *proc_pid_make_inode(struct super_block * sb,
1737 				  struct task_struct *task, umode_t mode)
1738 {
1739 	struct inode * inode;
1740 	struct proc_inode *ei;
1741 
1742 	/* We need a new inode */
1743 
1744 	inode = new_inode(sb);
1745 	if (!inode)
1746 		goto out;
1747 
1748 	/* Common stuff */
1749 	ei = PROC_I(inode);
1750 	inode->i_mode = mode;
1751 	inode->i_ino = get_next_ino();
1752 	inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
1753 	inode->i_op = &proc_def_inode_operations;
1754 
1755 	/*
1756 	 * grab the reference to task.
1757 	 */
1758 	ei->pid = get_task_pid(task, PIDTYPE_PID);
1759 	if (!ei->pid)
1760 		goto out_unlock;
1761 
1762 	task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
1763 	security_task_to_inode(task, inode);
1764 
1765 out:
1766 	return inode;
1767 
1768 out_unlock:
1769 	iput(inode);
1770 	return NULL;
1771 }
1772 
1773 int pid_getattr(const struct path *path, struct kstat *stat,
1774 		u32 request_mask, unsigned int query_flags)
1775 {
1776 	struct inode *inode = d_inode(path->dentry);
1777 	struct task_struct *task;
1778 	struct pid_namespace *pid = path->dentry->d_sb->s_fs_info;
1779 
1780 	generic_fillattr(inode, stat);
1781 
1782 	rcu_read_lock();
1783 	stat->uid = GLOBAL_ROOT_UID;
1784 	stat->gid = GLOBAL_ROOT_GID;
1785 	task = pid_task(proc_pid(inode), PIDTYPE_PID);
1786 	if (task) {
1787 		if (!has_pid_permissions(pid, task, HIDEPID_INVISIBLE)) {
1788 			rcu_read_unlock();
1789 			/*
1790 			 * This doesn't prevent learning whether PID exists,
1791 			 * it only makes getattr() consistent with readdir().
1792 			 */
1793 			return -ENOENT;
1794 		}
1795 		task_dump_owner(task, inode->i_mode, &stat->uid, &stat->gid);
1796 	}
1797 	rcu_read_unlock();
1798 	return 0;
1799 }
1800 
1801 /* dentry stuff */
1802 
1803 /*
1804  *	Exceptional case: normally we are not allowed to unhash a busy
1805  * directory. In this case, however, we can do it - no aliasing problems
1806  * due to the way we treat inodes.
1807  *
1808  * Rewrite the inode's ownerships here because the owning task may have
1809  * performed a setuid(), etc.
1810  *
1811  */
1812 int pid_revalidate(struct dentry *dentry, unsigned int flags)
1813 {
1814 	struct inode *inode;
1815 	struct task_struct *task;
1816 
1817 	if (flags & LOOKUP_RCU)
1818 		return -ECHILD;
1819 
1820 	inode = d_inode(dentry);
1821 	task = get_proc_task(inode);
1822 
1823 	if (task) {
1824 		task_dump_owner(task, inode->i_mode, &inode->i_uid, &inode->i_gid);
1825 
1826 		inode->i_mode &= ~(S_ISUID | S_ISGID);
1827 		security_task_to_inode(task, inode);
1828 		put_task_struct(task);
1829 		return 1;
1830 	}
1831 	return 0;
1832 }
1833 
1834 static inline bool proc_inode_is_dead(struct inode *inode)
1835 {
1836 	return !proc_pid(inode)->tasks[PIDTYPE_PID].first;
1837 }
1838 
1839 int pid_delete_dentry(const struct dentry *dentry)
1840 {
1841 	/* Is the task we represent dead?
1842 	 * If so, then don't put the dentry on the lru list,
1843 	 * kill it immediately.
1844 	 */
1845 	return proc_inode_is_dead(d_inode(dentry));
1846 }
1847 
1848 const struct dentry_operations pid_dentry_operations =
1849 {
1850 	.d_revalidate	= pid_revalidate,
1851 	.d_delete	= pid_delete_dentry,
1852 };
1853 
1854 /* Lookups */
1855 
1856 /*
1857  * Fill a directory entry.
1858  *
1859  * If possible create the dcache entry and derive our inode number and
1860  * file type from dcache entry.
1861  *
1862  * Since all of the proc inode numbers are dynamically generated, the inode
1863  * numbers do not exist until the inode is cache.  This means creating the
1864  * the dcache entry in readdir is necessary to keep the inode numbers
1865  * reported by readdir in sync with the inode numbers reported
1866  * by stat.
1867  */
1868 bool proc_fill_cache(struct file *file, struct dir_context *ctx,
1869 	const char *name, int len,
1870 	instantiate_t instantiate, struct task_struct *task, const void *ptr)
1871 {
1872 	struct dentry *child, *dir = file->f_path.dentry;
1873 	struct qstr qname = QSTR_INIT(name, len);
1874 	struct inode *inode;
1875 	unsigned type;
1876 	ino_t ino;
1877 
1878 	child = d_hash_and_lookup(dir, &qname);
1879 	if (!child) {
1880 		DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
1881 		child = d_alloc_parallel(dir, &qname, &wq);
1882 		if (IS_ERR(child))
1883 			goto end_instantiate;
1884 		if (d_in_lookup(child)) {
1885 			int err = instantiate(d_inode(dir), child, task, ptr);
1886 			d_lookup_done(child);
1887 			if (err < 0) {
1888 				dput(child);
1889 				goto end_instantiate;
1890 			}
1891 		}
1892 	}
1893 	inode = d_inode(child);
1894 	ino = inode->i_ino;
1895 	type = inode->i_mode >> 12;
1896 	dput(child);
1897 	return dir_emit(ctx, name, len, ino, type);
1898 
1899 end_instantiate:
1900 	return dir_emit(ctx, name, len, 1, DT_UNKNOWN);
1901 }
1902 
1903 /*
1904  * dname_to_vma_addr - maps a dentry name into two unsigned longs
1905  * which represent vma start and end addresses.
1906  */
1907 static int dname_to_vma_addr(struct dentry *dentry,
1908 			     unsigned long *start, unsigned long *end)
1909 {
1910 	if (sscanf(dentry->d_name.name, "%lx-%lx", start, end) != 2)
1911 		return -EINVAL;
1912 
1913 	return 0;
1914 }
1915 
1916 static int map_files_d_revalidate(struct dentry *dentry, unsigned int flags)
1917 {
1918 	unsigned long vm_start, vm_end;
1919 	bool exact_vma_exists = false;
1920 	struct mm_struct *mm = NULL;
1921 	struct task_struct *task;
1922 	struct inode *inode;
1923 	int status = 0;
1924 
1925 	if (flags & LOOKUP_RCU)
1926 		return -ECHILD;
1927 
1928 	inode = d_inode(dentry);
1929 	task = get_proc_task(inode);
1930 	if (!task)
1931 		goto out_notask;
1932 
1933 	mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
1934 	if (IS_ERR_OR_NULL(mm))
1935 		goto out;
1936 
1937 	if (!dname_to_vma_addr(dentry, &vm_start, &vm_end)) {
1938 		down_read(&mm->mmap_sem);
1939 		exact_vma_exists = !!find_exact_vma(mm, vm_start, vm_end);
1940 		up_read(&mm->mmap_sem);
1941 	}
1942 
1943 	mmput(mm);
1944 
1945 	if (exact_vma_exists) {
1946 		task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
1947 
1948 		security_task_to_inode(task, inode);
1949 		status = 1;
1950 	}
1951 
1952 out:
1953 	put_task_struct(task);
1954 
1955 out_notask:
1956 	return status;
1957 }
1958 
1959 static const struct dentry_operations tid_map_files_dentry_operations = {
1960 	.d_revalidate	= map_files_d_revalidate,
1961 	.d_delete	= pid_delete_dentry,
1962 };
1963 
1964 static int map_files_get_link(struct dentry *dentry, struct path *path)
1965 {
1966 	unsigned long vm_start, vm_end;
1967 	struct vm_area_struct *vma;
1968 	struct task_struct *task;
1969 	struct mm_struct *mm;
1970 	int rc;
1971 
1972 	rc = -ENOENT;
1973 	task = get_proc_task(d_inode(dentry));
1974 	if (!task)
1975 		goto out;
1976 
1977 	mm = get_task_mm(task);
1978 	put_task_struct(task);
1979 	if (!mm)
1980 		goto out;
1981 
1982 	rc = dname_to_vma_addr(dentry, &vm_start, &vm_end);
1983 	if (rc)
1984 		goto out_mmput;
1985 
1986 	rc = -ENOENT;
1987 	down_read(&mm->mmap_sem);
1988 	vma = find_exact_vma(mm, vm_start, vm_end);
1989 	if (vma && vma->vm_file) {
1990 		*path = vma->vm_file->f_path;
1991 		path_get(path);
1992 		rc = 0;
1993 	}
1994 	up_read(&mm->mmap_sem);
1995 
1996 out_mmput:
1997 	mmput(mm);
1998 out:
1999 	return rc;
2000 }
2001 
2002 struct map_files_info {
2003 	fmode_t		mode;
2004 	unsigned int	len;
2005 	unsigned char	name[4*sizeof(long)+2]; /* max: %lx-%lx\0 */
2006 };
2007 
2008 /*
2009  * Only allow CAP_SYS_ADMIN to follow the links, due to concerns about how the
2010  * symlinks may be used to bypass permissions on ancestor directories in the
2011  * path to the file in question.
2012  */
2013 static const char *
2014 proc_map_files_get_link(struct dentry *dentry,
2015 			struct inode *inode,
2016 		        struct delayed_call *done)
2017 {
2018 	if (!capable(CAP_SYS_ADMIN))
2019 		return ERR_PTR(-EPERM);
2020 
2021 	return proc_pid_get_link(dentry, inode, done);
2022 }
2023 
2024 /*
2025  * Identical to proc_pid_link_inode_operations except for get_link()
2026  */
2027 static const struct inode_operations proc_map_files_link_inode_operations = {
2028 	.readlink	= proc_pid_readlink,
2029 	.get_link	= proc_map_files_get_link,
2030 	.setattr	= proc_setattr,
2031 };
2032 
2033 static int
2034 proc_map_files_instantiate(struct inode *dir, struct dentry *dentry,
2035 			   struct task_struct *task, const void *ptr)
2036 {
2037 	fmode_t mode = (fmode_t)(unsigned long)ptr;
2038 	struct proc_inode *ei;
2039 	struct inode *inode;
2040 
2041 	inode = proc_pid_make_inode(dir->i_sb, task, S_IFLNK |
2042 				    ((mode & FMODE_READ ) ? S_IRUSR : 0) |
2043 				    ((mode & FMODE_WRITE) ? S_IWUSR : 0));
2044 	if (!inode)
2045 		return -ENOENT;
2046 
2047 	ei = PROC_I(inode);
2048 	ei->op.proc_get_link = map_files_get_link;
2049 
2050 	inode->i_op = &proc_map_files_link_inode_operations;
2051 	inode->i_size = 64;
2052 
2053 	d_set_d_op(dentry, &tid_map_files_dentry_operations);
2054 	d_add(dentry, inode);
2055 
2056 	return 0;
2057 }
2058 
2059 static struct dentry *proc_map_files_lookup(struct inode *dir,
2060 		struct dentry *dentry, unsigned int flags)
2061 {
2062 	unsigned long vm_start, vm_end;
2063 	struct vm_area_struct *vma;
2064 	struct task_struct *task;
2065 	int result;
2066 	struct mm_struct *mm;
2067 
2068 	result = -ENOENT;
2069 	task = get_proc_task(dir);
2070 	if (!task)
2071 		goto out;
2072 
2073 	result = -EACCES;
2074 	if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
2075 		goto out_put_task;
2076 
2077 	result = -ENOENT;
2078 	if (dname_to_vma_addr(dentry, &vm_start, &vm_end))
2079 		goto out_put_task;
2080 
2081 	mm = get_task_mm(task);
2082 	if (!mm)
2083 		goto out_put_task;
2084 
2085 	down_read(&mm->mmap_sem);
2086 	vma = find_exact_vma(mm, vm_start, vm_end);
2087 	if (!vma)
2088 		goto out_no_vma;
2089 
2090 	if (vma->vm_file)
2091 		result = proc_map_files_instantiate(dir, dentry, task,
2092 				(void *)(unsigned long)vma->vm_file->f_mode);
2093 
2094 out_no_vma:
2095 	up_read(&mm->mmap_sem);
2096 	mmput(mm);
2097 out_put_task:
2098 	put_task_struct(task);
2099 out:
2100 	return ERR_PTR(result);
2101 }
2102 
2103 static const struct inode_operations proc_map_files_inode_operations = {
2104 	.lookup		= proc_map_files_lookup,
2105 	.permission	= proc_fd_permission,
2106 	.setattr	= proc_setattr,
2107 };
2108 
2109 static int
2110 proc_map_files_readdir(struct file *file, struct dir_context *ctx)
2111 {
2112 	struct vm_area_struct *vma;
2113 	struct task_struct *task;
2114 	struct mm_struct *mm;
2115 	unsigned long nr_files, pos, i;
2116 	struct flex_array *fa = NULL;
2117 	struct map_files_info info;
2118 	struct map_files_info *p;
2119 	int ret;
2120 
2121 	ret = -ENOENT;
2122 	task = get_proc_task(file_inode(file));
2123 	if (!task)
2124 		goto out;
2125 
2126 	ret = -EACCES;
2127 	if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
2128 		goto out_put_task;
2129 
2130 	ret = 0;
2131 	if (!dir_emit_dots(file, ctx))
2132 		goto out_put_task;
2133 
2134 	mm = get_task_mm(task);
2135 	if (!mm)
2136 		goto out_put_task;
2137 	down_read(&mm->mmap_sem);
2138 
2139 	nr_files = 0;
2140 
2141 	/*
2142 	 * We need two passes here:
2143 	 *
2144 	 *  1) Collect vmas of mapped files with mmap_sem taken
2145 	 *  2) Release mmap_sem and instantiate entries
2146 	 *
2147 	 * otherwise we get lockdep complained, since filldir()
2148 	 * routine might require mmap_sem taken in might_fault().
2149 	 */
2150 
2151 	for (vma = mm->mmap, pos = 2; vma; vma = vma->vm_next) {
2152 		if (vma->vm_file && ++pos > ctx->pos)
2153 			nr_files++;
2154 	}
2155 
2156 	if (nr_files) {
2157 		fa = flex_array_alloc(sizeof(info), nr_files,
2158 					GFP_KERNEL);
2159 		if (!fa || flex_array_prealloc(fa, 0, nr_files,
2160 						GFP_KERNEL)) {
2161 			ret = -ENOMEM;
2162 			if (fa)
2163 				flex_array_free(fa);
2164 			up_read(&mm->mmap_sem);
2165 			mmput(mm);
2166 			goto out_put_task;
2167 		}
2168 		for (i = 0, vma = mm->mmap, pos = 2; vma;
2169 				vma = vma->vm_next) {
2170 			if (!vma->vm_file)
2171 				continue;
2172 			if (++pos <= ctx->pos)
2173 				continue;
2174 
2175 			info.mode = vma->vm_file->f_mode;
2176 			info.len = snprintf(info.name,
2177 					sizeof(info.name), "%lx-%lx",
2178 					vma->vm_start, vma->vm_end);
2179 			if (flex_array_put(fa, i++, &info, GFP_KERNEL))
2180 				BUG();
2181 		}
2182 	}
2183 	up_read(&mm->mmap_sem);
2184 
2185 	for (i = 0; i < nr_files; i++) {
2186 		p = flex_array_get(fa, i);
2187 		if (!proc_fill_cache(file, ctx,
2188 				      p->name, p->len,
2189 				      proc_map_files_instantiate,
2190 				      task,
2191 				      (void *)(unsigned long)p->mode))
2192 			break;
2193 		ctx->pos++;
2194 	}
2195 	if (fa)
2196 		flex_array_free(fa);
2197 	mmput(mm);
2198 
2199 out_put_task:
2200 	put_task_struct(task);
2201 out:
2202 	return ret;
2203 }
2204 
2205 static const struct file_operations proc_map_files_operations = {
2206 	.read		= generic_read_dir,
2207 	.iterate_shared	= proc_map_files_readdir,
2208 	.llseek		= generic_file_llseek,
2209 };
2210 
2211 #if defined(CONFIG_CHECKPOINT_RESTORE) && defined(CONFIG_POSIX_TIMERS)
2212 struct timers_private {
2213 	struct pid *pid;
2214 	struct task_struct *task;
2215 	struct sighand_struct *sighand;
2216 	struct pid_namespace *ns;
2217 	unsigned long flags;
2218 };
2219 
2220 static void *timers_start(struct seq_file *m, loff_t *pos)
2221 {
2222 	struct timers_private *tp = m->private;
2223 
2224 	tp->task = get_pid_task(tp->pid, PIDTYPE_PID);
2225 	if (!tp->task)
2226 		return ERR_PTR(-ESRCH);
2227 
2228 	tp->sighand = lock_task_sighand(tp->task, &tp->flags);
2229 	if (!tp->sighand)
2230 		return ERR_PTR(-ESRCH);
2231 
2232 	return seq_list_start(&tp->task->signal->posix_timers, *pos);
2233 }
2234 
2235 static void *timers_next(struct seq_file *m, void *v, loff_t *pos)
2236 {
2237 	struct timers_private *tp = m->private;
2238 	return seq_list_next(v, &tp->task->signal->posix_timers, pos);
2239 }
2240 
2241 static void timers_stop(struct seq_file *m, void *v)
2242 {
2243 	struct timers_private *tp = m->private;
2244 
2245 	if (tp->sighand) {
2246 		unlock_task_sighand(tp->task, &tp->flags);
2247 		tp->sighand = NULL;
2248 	}
2249 
2250 	if (tp->task) {
2251 		put_task_struct(tp->task);
2252 		tp->task = NULL;
2253 	}
2254 }
2255 
2256 static int show_timer(struct seq_file *m, void *v)
2257 {
2258 	struct k_itimer *timer;
2259 	struct timers_private *tp = m->private;
2260 	int notify;
2261 	static const char * const nstr[] = {
2262 		[SIGEV_SIGNAL] = "signal",
2263 		[SIGEV_NONE] = "none",
2264 		[SIGEV_THREAD] = "thread",
2265 	};
2266 
2267 	timer = list_entry((struct list_head *)v, struct k_itimer, list);
2268 	notify = timer->it_sigev_notify;
2269 
2270 	seq_printf(m, "ID: %d\n", timer->it_id);
2271 	seq_printf(m, "signal: %d/%px\n",
2272 		   timer->sigq->info.si_signo,
2273 		   timer->sigq->info.si_value.sival_ptr);
2274 	seq_printf(m, "notify: %s/%s.%d\n",
2275 		   nstr[notify & ~SIGEV_THREAD_ID],
2276 		   (notify & SIGEV_THREAD_ID) ? "tid" : "pid",
2277 		   pid_nr_ns(timer->it_pid, tp->ns));
2278 	seq_printf(m, "ClockID: %d\n", timer->it_clock);
2279 
2280 	return 0;
2281 }
2282 
2283 static const struct seq_operations proc_timers_seq_ops = {
2284 	.start	= timers_start,
2285 	.next	= timers_next,
2286 	.stop	= timers_stop,
2287 	.show	= show_timer,
2288 };
2289 
2290 static int proc_timers_open(struct inode *inode, struct file *file)
2291 {
2292 	struct timers_private *tp;
2293 
2294 	tp = __seq_open_private(file, &proc_timers_seq_ops,
2295 			sizeof(struct timers_private));
2296 	if (!tp)
2297 		return -ENOMEM;
2298 
2299 	tp->pid = proc_pid(inode);
2300 	tp->ns = inode->i_sb->s_fs_info;
2301 	return 0;
2302 }
2303 
2304 static const struct file_operations proc_timers_operations = {
2305 	.open		= proc_timers_open,
2306 	.read		= seq_read,
2307 	.llseek		= seq_lseek,
2308 	.release	= seq_release_private,
2309 };
2310 #endif
2311 
2312 static ssize_t timerslack_ns_write(struct file *file, const char __user *buf,
2313 					size_t count, loff_t *offset)
2314 {
2315 	struct inode *inode = file_inode(file);
2316 	struct task_struct *p;
2317 	u64 slack_ns;
2318 	int err;
2319 
2320 	err = kstrtoull_from_user(buf, count, 10, &slack_ns);
2321 	if (err < 0)
2322 		return err;
2323 
2324 	p = get_proc_task(inode);
2325 	if (!p)
2326 		return -ESRCH;
2327 
2328 	if (p != current) {
2329 		if (!capable(CAP_SYS_NICE)) {
2330 			count = -EPERM;
2331 			goto out;
2332 		}
2333 
2334 		err = security_task_setscheduler(p);
2335 		if (err) {
2336 			count = err;
2337 			goto out;
2338 		}
2339 	}
2340 
2341 	task_lock(p);
2342 	if (slack_ns == 0)
2343 		p->timer_slack_ns = p->default_timer_slack_ns;
2344 	else
2345 		p->timer_slack_ns = slack_ns;
2346 	task_unlock(p);
2347 
2348 out:
2349 	put_task_struct(p);
2350 
2351 	return count;
2352 }
2353 
2354 static int timerslack_ns_show(struct seq_file *m, void *v)
2355 {
2356 	struct inode *inode = m->private;
2357 	struct task_struct *p;
2358 	int err = 0;
2359 
2360 	p = get_proc_task(inode);
2361 	if (!p)
2362 		return -ESRCH;
2363 
2364 	if (p != current) {
2365 
2366 		if (!capable(CAP_SYS_NICE)) {
2367 			err = -EPERM;
2368 			goto out;
2369 		}
2370 		err = security_task_getscheduler(p);
2371 		if (err)
2372 			goto out;
2373 	}
2374 
2375 	task_lock(p);
2376 	seq_printf(m, "%llu\n", p->timer_slack_ns);
2377 	task_unlock(p);
2378 
2379 out:
2380 	put_task_struct(p);
2381 
2382 	return err;
2383 }
2384 
2385 static int timerslack_ns_open(struct inode *inode, struct file *filp)
2386 {
2387 	return single_open(filp, timerslack_ns_show, inode);
2388 }
2389 
2390 static const struct file_operations proc_pid_set_timerslack_ns_operations = {
2391 	.open		= timerslack_ns_open,
2392 	.read		= seq_read,
2393 	.write		= timerslack_ns_write,
2394 	.llseek		= seq_lseek,
2395 	.release	= single_release,
2396 };
2397 
2398 static int proc_pident_instantiate(struct inode *dir,
2399 	struct dentry *dentry, struct task_struct *task, const void *ptr)
2400 {
2401 	const struct pid_entry *p = ptr;
2402 	struct inode *inode;
2403 	struct proc_inode *ei;
2404 
2405 	inode = proc_pid_make_inode(dir->i_sb, task, p->mode);
2406 	if (!inode)
2407 		goto out;
2408 
2409 	ei = PROC_I(inode);
2410 	if (S_ISDIR(inode->i_mode))
2411 		set_nlink(inode, 2);	/* Use getattr to fix if necessary */
2412 	if (p->iop)
2413 		inode->i_op = p->iop;
2414 	if (p->fop)
2415 		inode->i_fop = p->fop;
2416 	ei->op = p->op;
2417 	d_set_d_op(dentry, &pid_dentry_operations);
2418 	d_add(dentry, inode);
2419 	/* Close the race of the process dying before we return the dentry */
2420 	if (pid_revalidate(dentry, 0))
2421 		return 0;
2422 out:
2423 	return -ENOENT;
2424 }
2425 
2426 static struct dentry *proc_pident_lookup(struct inode *dir,
2427 					 struct dentry *dentry,
2428 					 const struct pid_entry *ents,
2429 					 unsigned int nents)
2430 {
2431 	int error;
2432 	struct task_struct *task = get_proc_task(dir);
2433 	const struct pid_entry *p, *last;
2434 
2435 	error = -ENOENT;
2436 
2437 	if (!task)
2438 		goto out_no_task;
2439 
2440 	/*
2441 	 * Yes, it does not scale. And it should not. Don't add
2442 	 * new entries into /proc/<tgid>/ without very good reasons.
2443 	 */
2444 	last = &ents[nents];
2445 	for (p = ents; p < last; p++) {
2446 		if (p->len != dentry->d_name.len)
2447 			continue;
2448 		if (!memcmp(dentry->d_name.name, p->name, p->len))
2449 			break;
2450 	}
2451 	if (p >= last)
2452 		goto out;
2453 
2454 	error = proc_pident_instantiate(dir, dentry, task, p);
2455 out:
2456 	put_task_struct(task);
2457 out_no_task:
2458 	return ERR_PTR(error);
2459 }
2460 
2461 static int proc_pident_readdir(struct file *file, struct dir_context *ctx,
2462 		const struct pid_entry *ents, unsigned int nents)
2463 {
2464 	struct task_struct *task = get_proc_task(file_inode(file));
2465 	const struct pid_entry *p;
2466 
2467 	if (!task)
2468 		return -ENOENT;
2469 
2470 	if (!dir_emit_dots(file, ctx))
2471 		goto out;
2472 
2473 	if (ctx->pos >= nents + 2)
2474 		goto out;
2475 
2476 	for (p = ents + (ctx->pos - 2); p < ents + nents; p++) {
2477 		if (!proc_fill_cache(file, ctx, p->name, p->len,
2478 				proc_pident_instantiate, task, p))
2479 			break;
2480 		ctx->pos++;
2481 	}
2482 out:
2483 	put_task_struct(task);
2484 	return 0;
2485 }
2486 
2487 #ifdef CONFIG_SECURITY
2488 static ssize_t proc_pid_attr_read(struct file * file, char __user * buf,
2489 				  size_t count, loff_t *ppos)
2490 {
2491 	struct inode * inode = file_inode(file);
2492 	char *p = NULL;
2493 	ssize_t length;
2494 	struct task_struct *task = get_proc_task(inode);
2495 
2496 	if (!task)
2497 		return -ESRCH;
2498 
2499 	length = security_getprocattr(task,
2500 				      (char*)file->f_path.dentry->d_name.name,
2501 				      &p);
2502 	put_task_struct(task);
2503 	if (length > 0)
2504 		length = simple_read_from_buffer(buf, count, ppos, p, length);
2505 	kfree(p);
2506 	return length;
2507 }
2508 
2509 static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
2510 				   size_t count, loff_t *ppos)
2511 {
2512 	struct inode * inode = file_inode(file);
2513 	void *page;
2514 	ssize_t length;
2515 	struct task_struct *task = get_proc_task(inode);
2516 
2517 	length = -ESRCH;
2518 	if (!task)
2519 		goto out_no_task;
2520 
2521 	/* A task may only write its own attributes. */
2522 	length = -EACCES;
2523 	if (current != task)
2524 		goto out;
2525 
2526 	if (count > PAGE_SIZE)
2527 		count = PAGE_SIZE;
2528 
2529 	/* No partial writes. */
2530 	length = -EINVAL;
2531 	if (*ppos != 0)
2532 		goto out;
2533 
2534 	page = memdup_user(buf, count);
2535 	if (IS_ERR(page)) {
2536 		length = PTR_ERR(page);
2537 		goto out;
2538 	}
2539 
2540 	/* Guard against adverse ptrace interaction */
2541 	length = mutex_lock_interruptible(&current->signal->cred_guard_mutex);
2542 	if (length < 0)
2543 		goto out_free;
2544 
2545 	length = security_setprocattr(file->f_path.dentry->d_name.name,
2546 				      page, count);
2547 	mutex_unlock(&current->signal->cred_guard_mutex);
2548 out_free:
2549 	kfree(page);
2550 out:
2551 	put_task_struct(task);
2552 out_no_task:
2553 	return length;
2554 }
2555 
2556 static const struct file_operations proc_pid_attr_operations = {
2557 	.read		= proc_pid_attr_read,
2558 	.write		= proc_pid_attr_write,
2559 	.llseek		= generic_file_llseek,
2560 };
2561 
2562 static const struct pid_entry attr_dir_stuff[] = {
2563 	REG("current",    S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2564 	REG("prev",       S_IRUGO,	   proc_pid_attr_operations),
2565 	REG("exec",       S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2566 	REG("fscreate",   S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2567 	REG("keycreate",  S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2568 	REG("sockcreate", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2569 };
2570 
2571 static int proc_attr_dir_readdir(struct file *file, struct dir_context *ctx)
2572 {
2573 	return proc_pident_readdir(file, ctx,
2574 				   attr_dir_stuff, ARRAY_SIZE(attr_dir_stuff));
2575 }
2576 
2577 static const struct file_operations proc_attr_dir_operations = {
2578 	.read		= generic_read_dir,
2579 	.iterate_shared	= proc_attr_dir_readdir,
2580 	.llseek		= generic_file_llseek,
2581 };
2582 
2583 static struct dentry *proc_attr_dir_lookup(struct inode *dir,
2584 				struct dentry *dentry, unsigned int flags)
2585 {
2586 	return proc_pident_lookup(dir, dentry,
2587 				  attr_dir_stuff, ARRAY_SIZE(attr_dir_stuff));
2588 }
2589 
2590 static const struct inode_operations proc_attr_dir_inode_operations = {
2591 	.lookup		= proc_attr_dir_lookup,
2592 	.getattr	= pid_getattr,
2593 	.setattr	= proc_setattr,
2594 };
2595 
2596 #endif
2597 
2598 #ifdef CONFIG_ELF_CORE
2599 static ssize_t proc_coredump_filter_read(struct file *file, char __user *buf,
2600 					 size_t count, loff_t *ppos)
2601 {
2602 	struct task_struct *task = get_proc_task(file_inode(file));
2603 	struct mm_struct *mm;
2604 	char buffer[PROC_NUMBUF];
2605 	size_t len;
2606 	int ret;
2607 
2608 	if (!task)
2609 		return -ESRCH;
2610 
2611 	ret = 0;
2612 	mm = get_task_mm(task);
2613 	if (mm) {
2614 		len = snprintf(buffer, sizeof(buffer), "%08lx\n",
2615 			       ((mm->flags & MMF_DUMP_FILTER_MASK) >>
2616 				MMF_DUMP_FILTER_SHIFT));
2617 		mmput(mm);
2618 		ret = simple_read_from_buffer(buf, count, ppos, buffer, len);
2619 	}
2620 
2621 	put_task_struct(task);
2622 
2623 	return ret;
2624 }
2625 
2626 static ssize_t proc_coredump_filter_write(struct file *file,
2627 					  const char __user *buf,
2628 					  size_t count,
2629 					  loff_t *ppos)
2630 {
2631 	struct task_struct *task;
2632 	struct mm_struct *mm;
2633 	unsigned int val;
2634 	int ret;
2635 	int i;
2636 	unsigned long mask;
2637 
2638 	ret = kstrtouint_from_user(buf, count, 0, &val);
2639 	if (ret < 0)
2640 		return ret;
2641 
2642 	ret = -ESRCH;
2643 	task = get_proc_task(file_inode(file));
2644 	if (!task)
2645 		goto out_no_task;
2646 
2647 	mm = get_task_mm(task);
2648 	if (!mm)
2649 		goto out_no_mm;
2650 	ret = 0;
2651 
2652 	for (i = 0, mask = 1; i < MMF_DUMP_FILTER_BITS; i++, mask <<= 1) {
2653 		if (val & mask)
2654 			set_bit(i + MMF_DUMP_FILTER_SHIFT, &mm->flags);
2655 		else
2656 			clear_bit(i + MMF_DUMP_FILTER_SHIFT, &mm->flags);
2657 	}
2658 
2659 	mmput(mm);
2660  out_no_mm:
2661 	put_task_struct(task);
2662  out_no_task:
2663 	if (ret < 0)
2664 		return ret;
2665 	return count;
2666 }
2667 
2668 static const struct file_operations proc_coredump_filter_operations = {
2669 	.read		= proc_coredump_filter_read,
2670 	.write		= proc_coredump_filter_write,
2671 	.llseek		= generic_file_llseek,
2672 };
2673 #endif
2674 
2675 #ifdef CONFIG_TASK_IO_ACCOUNTING
2676 static int do_io_accounting(struct task_struct *task, struct seq_file *m, int whole)
2677 {
2678 	struct task_io_accounting acct = task->ioac;
2679 	unsigned long flags;
2680 	int result;
2681 
2682 	result = mutex_lock_killable(&task->signal->cred_guard_mutex);
2683 	if (result)
2684 		return result;
2685 
2686 	if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) {
2687 		result = -EACCES;
2688 		goto out_unlock;
2689 	}
2690 
2691 	if (whole && lock_task_sighand(task, &flags)) {
2692 		struct task_struct *t = task;
2693 
2694 		task_io_accounting_add(&acct, &task->signal->ioac);
2695 		while_each_thread(task, t)
2696 			task_io_accounting_add(&acct, &t->ioac);
2697 
2698 		unlock_task_sighand(task, &flags);
2699 	}
2700 	seq_printf(m,
2701 		   "rchar: %llu\n"
2702 		   "wchar: %llu\n"
2703 		   "syscr: %llu\n"
2704 		   "syscw: %llu\n"
2705 		   "read_bytes: %llu\n"
2706 		   "write_bytes: %llu\n"
2707 		   "cancelled_write_bytes: %llu\n",
2708 		   (unsigned long long)acct.rchar,
2709 		   (unsigned long long)acct.wchar,
2710 		   (unsigned long long)acct.syscr,
2711 		   (unsigned long long)acct.syscw,
2712 		   (unsigned long long)acct.read_bytes,
2713 		   (unsigned long long)acct.write_bytes,
2714 		   (unsigned long long)acct.cancelled_write_bytes);
2715 	result = 0;
2716 
2717 out_unlock:
2718 	mutex_unlock(&task->signal->cred_guard_mutex);
2719 	return result;
2720 }
2721 
2722 static int proc_tid_io_accounting(struct seq_file *m, struct pid_namespace *ns,
2723 				  struct pid *pid, struct task_struct *task)
2724 {
2725 	return do_io_accounting(task, m, 0);
2726 }
2727 
2728 static int proc_tgid_io_accounting(struct seq_file *m, struct pid_namespace *ns,
2729 				   struct pid *pid, struct task_struct *task)
2730 {
2731 	return do_io_accounting(task, m, 1);
2732 }
2733 #endif /* CONFIG_TASK_IO_ACCOUNTING */
2734 
2735 #ifdef CONFIG_USER_NS
2736 static int proc_id_map_open(struct inode *inode, struct file *file,
2737 	const struct seq_operations *seq_ops)
2738 {
2739 	struct user_namespace *ns = NULL;
2740 	struct task_struct *task;
2741 	struct seq_file *seq;
2742 	int ret = -EINVAL;
2743 
2744 	task = get_proc_task(inode);
2745 	if (task) {
2746 		rcu_read_lock();
2747 		ns = get_user_ns(task_cred_xxx(task, user_ns));
2748 		rcu_read_unlock();
2749 		put_task_struct(task);
2750 	}
2751 	if (!ns)
2752 		goto err;
2753 
2754 	ret = seq_open(file, seq_ops);
2755 	if (ret)
2756 		goto err_put_ns;
2757 
2758 	seq = file->private_data;
2759 	seq->private = ns;
2760 
2761 	return 0;
2762 err_put_ns:
2763 	put_user_ns(ns);
2764 err:
2765 	return ret;
2766 }
2767 
2768 static int proc_id_map_release(struct inode *inode, struct file *file)
2769 {
2770 	struct seq_file *seq = file->private_data;
2771 	struct user_namespace *ns = seq->private;
2772 	put_user_ns(ns);
2773 	return seq_release(inode, file);
2774 }
2775 
2776 static int proc_uid_map_open(struct inode *inode, struct file *file)
2777 {
2778 	return proc_id_map_open(inode, file, &proc_uid_seq_operations);
2779 }
2780 
2781 static int proc_gid_map_open(struct inode *inode, struct file *file)
2782 {
2783 	return proc_id_map_open(inode, file, &proc_gid_seq_operations);
2784 }
2785 
2786 static int proc_projid_map_open(struct inode *inode, struct file *file)
2787 {
2788 	return proc_id_map_open(inode, file, &proc_projid_seq_operations);
2789 }
2790 
2791 static const struct file_operations proc_uid_map_operations = {
2792 	.open		= proc_uid_map_open,
2793 	.write		= proc_uid_map_write,
2794 	.read		= seq_read,
2795 	.llseek		= seq_lseek,
2796 	.release	= proc_id_map_release,
2797 };
2798 
2799 static const struct file_operations proc_gid_map_operations = {
2800 	.open		= proc_gid_map_open,
2801 	.write		= proc_gid_map_write,
2802 	.read		= seq_read,
2803 	.llseek		= seq_lseek,
2804 	.release	= proc_id_map_release,
2805 };
2806 
2807 static const struct file_operations proc_projid_map_operations = {
2808 	.open		= proc_projid_map_open,
2809 	.write		= proc_projid_map_write,
2810 	.read		= seq_read,
2811 	.llseek		= seq_lseek,
2812 	.release	= proc_id_map_release,
2813 };
2814 
2815 static int proc_setgroups_open(struct inode *inode, struct file *file)
2816 {
2817 	struct user_namespace *ns = NULL;
2818 	struct task_struct *task;
2819 	int ret;
2820 
2821 	ret = -ESRCH;
2822 	task = get_proc_task(inode);
2823 	if (task) {
2824 		rcu_read_lock();
2825 		ns = get_user_ns(task_cred_xxx(task, user_ns));
2826 		rcu_read_unlock();
2827 		put_task_struct(task);
2828 	}
2829 	if (!ns)
2830 		goto err;
2831 
2832 	if (file->f_mode & FMODE_WRITE) {
2833 		ret = -EACCES;
2834 		if (!ns_capable(ns, CAP_SYS_ADMIN))
2835 			goto err_put_ns;
2836 	}
2837 
2838 	ret = single_open(file, &proc_setgroups_show, ns);
2839 	if (ret)
2840 		goto err_put_ns;
2841 
2842 	return 0;
2843 err_put_ns:
2844 	put_user_ns(ns);
2845 err:
2846 	return ret;
2847 }
2848 
2849 static int proc_setgroups_release(struct inode *inode, struct file *file)
2850 {
2851 	struct seq_file *seq = file->private_data;
2852 	struct user_namespace *ns = seq->private;
2853 	int ret = single_release(inode, file);
2854 	put_user_ns(ns);
2855 	return ret;
2856 }
2857 
2858 static const struct file_operations proc_setgroups_operations = {
2859 	.open		= proc_setgroups_open,
2860 	.write		= proc_setgroups_write,
2861 	.read		= seq_read,
2862 	.llseek		= seq_lseek,
2863 	.release	= proc_setgroups_release,
2864 };
2865 #endif /* CONFIG_USER_NS */
2866 
2867 static int proc_pid_personality(struct seq_file *m, struct pid_namespace *ns,
2868 				struct pid *pid, struct task_struct *task)
2869 {
2870 	int err = lock_trace(task);
2871 	if (!err) {
2872 		seq_printf(m, "%08x\n", task->personality);
2873 		unlock_trace(task);
2874 	}
2875 	return err;
2876 }
2877 
2878 #ifdef CONFIG_LIVEPATCH
2879 static int proc_pid_patch_state(struct seq_file *m, struct pid_namespace *ns,
2880 				struct pid *pid, struct task_struct *task)
2881 {
2882 	seq_printf(m, "%d\n", task->patch_state);
2883 	return 0;
2884 }
2885 #endif /* CONFIG_LIVEPATCH */
2886 
2887 /*
2888  * Thread groups
2889  */
2890 static const struct file_operations proc_task_operations;
2891 static const struct inode_operations proc_task_inode_operations;
2892 
2893 static const struct pid_entry tgid_base_stuff[] = {
2894 	DIR("task",       S_IRUGO|S_IXUGO, proc_task_inode_operations, proc_task_operations),
2895 	DIR("fd",         S_IRUSR|S_IXUSR, proc_fd_inode_operations, proc_fd_operations),
2896 	DIR("map_files",  S_IRUSR|S_IXUSR, proc_map_files_inode_operations, proc_map_files_operations),
2897 	DIR("fdinfo",     S_IRUSR|S_IXUSR, proc_fdinfo_inode_operations, proc_fdinfo_operations),
2898 	DIR("ns",	  S_IRUSR|S_IXUGO, proc_ns_dir_inode_operations, proc_ns_dir_operations),
2899 #ifdef CONFIG_NET
2900 	DIR("net",        S_IRUGO|S_IXUGO, proc_net_inode_operations, proc_net_operations),
2901 #endif
2902 	REG("environ",    S_IRUSR, proc_environ_operations),
2903 	REG("auxv",       S_IRUSR, proc_auxv_operations),
2904 	ONE("status",     S_IRUGO, proc_pid_status),
2905 	ONE("personality", S_IRUSR, proc_pid_personality),
2906 	ONE("limits",	  S_IRUGO, proc_pid_limits),
2907 #ifdef CONFIG_SCHED_DEBUG
2908 	REG("sched",      S_IRUGO|S_IWUSR, proc_pid_sched_operations),
2909 #endif
2910 #ifdef CONFIG_SCHED_AUTOGROUP
2911 	REG("autogroup",  S_IRUGO|S_IWUSR, proc_pid_sched_autogroup_operations),
2912 #endif
2913 	REG("comm",      S_IRUGO|S_IWUSR, proc_pid_set_comm_operations),
2914 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
2915 	ONE("syscall",    S_IRUSR, proc_pid_syscall),
2916 #endif
2917 	REG("cmdline",    S_IRUGO, proc_pid_cmdline_ops),
2918 	ONE("stat",       S_IRUGO, proc_tgid_stat),
2919 	ONE("statm",      S_IRUGO, proc_pid_statm),
2920 	REG("maps",       S_IRUGO, proc_pid_maps_operations),
2921 #ifdef CONFIG_NUMA
2922 	REG("numa_maps",  S_IRUGO, proc_pid_numa_maps_operations),
2923 #endif
2924 	REG("mem",        S_IRUSR|S_IWUSR, proc_mem_operations),
2925 	LNK("cwd",        proc_cwd_link),
2926 	LNK("root",       proc_root_link),
2927 	LNK("exe",        proc_exe_link),
2928 	REG("mounts",     S_IRUGO, proc_mounts_operations),
2929 	REG("mountinfo",  S_IRUGO, proc_mountinfo_operations),
2930 	REG("mountstats", S_IRUSR, proc_mountstats_operations),
2931 #ifdef CONFIG_PROC_PAGE_MONITOR
2932 	REG("clear_refs", S_IWUSR, proc_clear_refs_operations),
2933 	REG("smaps",      S_IRUGO, proc_pid_smaps_operations),
2934 	REG("smaps_rollup", S_IRUGO, proc_pid_smaps_rollup_operations),
2935 	REG("pagemap",    S_IRUSR, proc_pagemap_operations),
2936 #endif
2937 #ifdef CONFIG_SECURITY
2938 	DIR("attr",       S_IRUGO|S_IXUGO, proc_attr_dir_inode_operations, proc_attr_dir_operations),
2939 #endif
2940 #ifdef CONFIG_KALLSYMS
2941 	ONE("wchan",      S_IRUGO, proc_pid_wchan),
2942 #endif
2943 #ifdef CONFIG_STACKTRACE
2944 	ONE("stack",      S_IRUSR, proc_pid_stack),
2945 #endif
2946 #ifdef CONFIG_SCHED_INFO
2947 	ONE("schedstat",  S_IRUGO, proc_pid_schedstat),
2948 #endif
2949 #ifdef CONFIG_LATENCYTOP
2950 	REG("latency",  S_IRUGO, proc_lstats_operations),
2951 #endif
2952 #ifdef CONFIG_PROC_PID_CPUSET
2953 	ONE("cpuset",     S_IRUGO, proc_cpuset_show),
2954 #endif
2955 #ifdef CONFIG_CGROUPS
2956 	ONE("cgroup",  S_IRUGO, proc_cgroup_show),
2957 #endif
2958 	ONE("oom_score",  S_IRUGO, proc_oom_score),
2959 	REG("oom_adj",    S_IRUGO|S_IWUSR, proc_oom_adj_operations),
2960 	REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
2961 #ifdef CONFIG_AUDITSYSCALL
2962 	REG("loginuid",   S_IWUSR|S_IRUGO, proc_loginuid_operations),
2963 	REG("sessionid",  S_IRUGO, proc_sessionid_operations),
2964 #endif
2965 #ifdef CONFIG_FAULT_INJECTION
2966 	REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
2967 	REG("fail-nth", 0644, proc_fail_nth_operations),
2968 #endif
2969 #ifdef CONFIG_ELF_CORE
2970 	REG("coredump_filter", S_IRUGO|S_IWUSR, proc_coredump_filter_operations),
2971 #endif
2972 #ifdef CONFIG_TASK_IO_ACCOUNTING
2973 	ONE("io",	S_IRUSR, proc_tgid_io_accounting),
2974 #endif
2975 #ifdef CONFIG_HARDWALL
2976 	ONE("hardwall",   S_IRUGO, proc_pid_hardwall),
2977 #endif
2978 #ifdef CONFIG_USER_NS
2979 	REG("uid_map",    S_IRUGO|S_IWUSR, proc_uid_map_operations),
2980 	REG("gid_map",    S_IRUGO|S_IWUSR, proc_gid_map_operations),
2981 	REG("projid_map", S_IRUGO|S_IWUSR, proc_projid_map_operations),
2982 	REG("setgroups",  S_IRUGO|S_IWUSR, proc_setgroups_operations),
2983 #endif
2984 #if defined(CONFIG_CHECKPOINT_RESTORE) && defined(CONFIG_POSIX_TIMERS)
2985 	REG("timers",	  S_IRUGO, proc_timers_operations),
2986 #endif
2987 	REG("timerslack_ns", S_IRUGO|S_IWUGO, proc_pid_set_timerslack_ns_operations),
2988 #ifdef CONFIG_LIVEPATCH
2989 	ONE("patch_state",  S_IRUSR, proc_pid_patch_state),
2990 #endif
2991 };
2992 
2993 static int proc_tgid_base_readdir(struct file *file, struct dir_context *ctx)
2994 {
2995 	return proc_pident_readdir(file, ctx,
2996 				   tgid_base_stuff, ARRAY_SIZE(tgid_base_stuff));
2997 }
2998 
2999 static const struct file_operations proc_tgid_base_operations = {
3000 	.read		= generic_read_dir,
3001 	.iterate_shared	= proc_tgid_base_readdir,
3002 	.llseek		= generic_file_llseek,
3003 };
3004 
3005 static struct dentry *proc_tgid_base_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
3006 {
3007 	return proc_pident_lookup(dir, dentry,
3008 				  tgid_base_stuff, ARRAY_SIZE(tgid_base_stuff));
3009 }
3010 
3011 static const struct inode_operations proc_tgid_base_inode_operations = {
3012 	.lookup		= proc_tgid_base_lookup,
3013 	.getattr	= pid_getattr,
3014 	.setattr	= proc_setattr,
3015 	.permission	= proc_pid_permission,
3016 };
3017 
3018 static void proc_flush_task_mnt(struct vfsmount *mnt, pid_t pid, pid_t tgid)
3019 {
3020 	struct dentry *dentry, *leader, *dir;
3021 	char buf[PROC_NUMBUF];
3022 	struct qstr name;
3023 
3024 	name.name = buf;
3025 	name.len = snprintf(buf, sizeof(buf), "%d", pid);
3026 	/* no ->d_hash() rejects on procfs */
3027 	dentry = d_hash_and_lookup(mnt->mnt_root, &name);
3028 	if (dentry) {
3029 		d_invalidate(dentry);
3030 		dput(dentry);
3031 	}
3032 
3033 	if (pid == tgid)
3034 		return;
3035 
3036 	name.name = buf;
3037 	name.len = snprintf(buf, sizeof(buf), "%d", tgid);
3038 	leader = d_hash_and_lookup(mnt->mnt_root, &name);
3039 	if (!leader)
3040 		goto out;
3041 
3042 	name.name = "task";
3043 	name.len = strlen(name.name);
3044 	dir = d_hash_and_lookup(leader, &name);
3045 	if (!dir)
3046 		goto out_put_leader;
3047 
3048 	name.name = buf;
3049 	name.len = snprintf(buf, sizeof(buf), "%d", pid);
3050 	dentry = d_hash_and_lookup(dir, &name);
3051 	if (dentry) {
3052 		d_invalidate(dentry);
3053 		dput(dentry);
3054 	}
3055 
3056 	dput(dir);
3057 out_put_leader:
3058 	dput(leader);
3059 out:
3060 	return;
3061 }
3062 
3063 /**
3064  * proc_flush_task -  Remove dcache entries for @task from the /proc dcache.
3065  * @task: task that should be flushed.
3066  *
3067  * When flushing dentries from proc, one needs to flush them from global
3068  * proc (proc_mnt) and from all the namespaces' procs this task was seen
3069  * in. This call is supposed to do all of this job.
3070  *
3071  * Looks in the dcache for
3072  * /proc/@pid
3073  * /proc/@tgid/task/@pid
3074  * if either directory is present flushes it and all of it'ts children
3075  * from the dcache.
3076  *
3077  * It is safe and reasonable to cache /proc entries for a task until
3078  * that task exits.  After that they just clog up the dcache with
3079  * useless entries, possibly causing useful dcache entries to be
3080  * flushed instead.  This routine is proved to flush those useless
3081  * dcache entries at process exit time.
3082  *
3083  * NOTE: This routine is just an optimization so it does not guarantee
3084  *       that no dcache entries will exist at process exit time it
3085  *       just makes it very unlikely that any will persist.
3086  */
3087 
3088 void proc_flush_task(struct task_struct *task)
3089 {
3090 	int i;
3091 	struct pid *pid, *tgid;
3092 	struct upid *upid;
3093 
3094 	pid = task_pid(task);
3095 	tgid = task_tgid(task);
3096 
3097 	for (i = 0; i <= pid->level; i++) {
3098 		upid = &pid->numbers[i];
3099 		proc_flush_task_mnt(upid->ns->proc_mnt, upid->nr,
3100 					tgid->numbers[i].nr);
3101 	}
3102 }
3103 
3104 static int proc_pid_instantiate(struct inode *dir,
3105 				   struct dentry * dentry,
3106 				   struct task_struct *task, const void *ptr)
3107 {
3108 	struct inode *inode;
3109 
3110 	inode = proc_pid_make_inode(dir->i_sb, task, S_IFDIR | S_IRUGO | S_IXUGO);
3111 	if (!inode)
3112 		goto out;
3113 
3114 	inode->i_op = &proc_tgid_base_inode_operations;
3115 	inode->i_fop = &proc_tgid_base_operations;
3116 	inode->i_flags|=S_IMMUTABLE;
3117 
3118 	set_nlink(inode, nlink_tgid);
3119 
3120 	d_set_d_op(dentry, &pid_dentry_operations);
3121 
3122 	d_add(dentry, inode);
3123 	/* Close the race of the process dying before we return the dentry */
3124 	if (pid_revalidate(dentry, 0))
3125 		return 0;
3126 out:
3127 	return -ENOENT;
3128 }
3129 
3130 struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)
3131 {
3132 	int result = -ENOENT;
3133 	struct task_struct *task;
3134 	unsigned tgid;
3135 	struct pid_namespace *ns;
3136 
3137 	tgid = name_to_int(&dentry->d_name);
3138 	if (tgid == ~0U)
3139 		goto out;
3140 
3141 	ns = dentry->d_sb->s_fs_info;
3142 	rcu_read_lock();
3143 	task = find_task_by_pid_ns(tgid, ns);
3144 	if (task)
3145 		get_task_struct(task);
3146 	rcu_read_unlock();
3147 	if (!task)
3148 		goto out;
3149 
3150 	result = proc_pid_instantiate(dir, dentry, task, NULL);
3151 	put_task_struct(task);
3152 out:
3153 	return ERR_PTR(result);
3154 }
3155 
3156 /*
3157  * Find the first task with tgid >= tgid
3158  *
3159  */
3160 struct tgid_iter {
3161 	unsigned int tgid;
3162 	struct task_struct *task;
3163 };
3164 static struct tgid_iter next_tgid(struct pid_namespace *ns, struct tgid_iter iter)
3165 {
3166 	struct pid *pid;
3167 
3168 	if (iter.task)
3169 		put_task_struct(iter.task);
3170 	rcu_read_lock();
3171 retry:
3172 	iter.task = NULL;
3173 	pid = find_ge_pid(iter.tgid, ns);
3174 	if (pid) {
3175 		iter.tgid = pid_nr_ns(pid, ns);
3176 		iter.task = pid_task(pid, PIDTYPE_PID);
3177 		/* What we to know is if the pid we have find is the
3178 		 * pid of a thread_group_leader.  Testing for task
3179 		 * being a thread_group_leader is the obvious thing
3180 		 * todo but there is a window when it fails, due to
3181 		 * the pid transfer logic in de_thread.
3182 		 *
3183 		 * So we perform the straight forward test of seeing
3184 		 * if the pid we have found is the pid of a thread
3185 		 * group leader, and don't worry if the task we have
3186 		 * found doesn't happen to be a thread group leader.
3187 		 * As we don't care in the case of readdir.
3188 		 */
3189 		if (!iter.task || !has_group_leader_pid(iter.task)) {
3190 			iter.tgid += 1;
3191 			goto retry;
3192 		}
3193 		get_task_struct(iter.task);
3194 	}
3195 	rcu_read_unlock();
3196 	return iter;
3197 }
3198 
3199 #define TGID_OFFSET (FIRST_PROCESS_ENTRY + 2)
3200 
3201 /* for the /proc/ directory itself, after non-process stuff has been done */
3202 int proc_pid_readdir(struct file *file, struct dir_context *ctx)
3203 {
3204 	struct tgid_iter iter;
3205 	struct pid_namespace *ns = file_inode(file)->i_sb->s_fs_info;
3206 	loff_t pos = ctx->pos;
3207 
3208 	if (pos >= PID_MAX_LIMIT + TGID_OFFSET)
3209 		return 0;
3210 
3211 	if (pos == TGID_OFFSET - 2) {
3212 		struct inode *inode = d_inode(ns->proc_self);
3213 		if (!dir_emit(ctx, "self", 4, inode->i_ino, DT_LNK))
3214 			return 0;
3215 		ctx->pos = pos = pos + 1;
3216 	}
3217 	if (pos == TGID_OFFSET - 1) {
3218 		struct inode *inode = d_inode(ns->proc_thread_self);
3219 		if (!dir_emit(ctx, "thread-self", 11, inode->i_ino, DT_LNK))
3220 			return 0;
3221 		ctx->pos = pos = pos + 1;
3222 	}
3223 	iter.tgid = pos - TGID_OFFSET;
3224 	iter.task = NULL;
3225 	for (iter = next_tgid(ns, iter);
3226 	     iter.task;
3227 	     iter.tgid += 1, iter = next_tgid(ns, iter)) {
3228 		char name[PROC_NUMBUF];
3229 		int len;
3230 
3231 		cond_resched();
3232 		if (!has_pid_permissions(ns, iter.task, HIDEPID_INVISIBLE))
3233 			continue;
3234 
3235 		len = snprintf(name, sizeof(name), "%d", iter.tgid);
3236 		ctx->pos = iter.tgid + TGID_OFFSET;
3237 		if (!proc_fill_cache(file, ctx, name, len,
3238 				     proc_pid_instantiate, iter.task, NULL)) {
3239 			put_task_struct(iter.task);
3240 			return 0;
3241 		}
3242 	}
3243 	ctx->pos = PID_MAX_LIMIT + TGID_OFFSET;
3244 	return 0;
3245 }
3246 
3247 /*
3248  * proc_tid_comm_permission is a special permission function exclusively
3249  * used for the node /proc/<pid>/task/<tid>/comm.
3250  * It bypasses generic permission checks in the case where a task of the same
3251  * task group attempts to access the node.
3252  * The rationale behind this is that glibc and bionic access this node for
3253  * cross thread naming (pthread_set/getname_np(!self)). However, if
3254  * PR_SET_DUMPABLE gets set to 0 this node among others becomes uid=0 gid=0,
3255  * which locks out the cross thread naming implementation.
3256  * This function makes sure that the node is always accessible for members of
3257  * same thread group.
3258  */
3259 static int proc_tid_comm_permission(struct inode *inode, int mask)
3260 {
3261 	bool is_same_tgroup;
3262 	struct task_struct *task;
3263 
3264 	task = get_proc_task(inode);
3265 	if (!task)
3266 		return -ESRCH;
3267 	is_same_tgroup = same_thread_group(current, task);
3268 	put_task_struct(task);
3269 
3270 	if (likely(is_same_tgroup && !(mask & MAY_EXEC))) {
3271 		/* This file (/proc/<pid>/task/<tid>/comm) can always be
3272 		 * read or written by the members of the corresponding
3273 		 * thread group.
3274 		 */
3275 		return 0;
3276 	}
3277 
3278 	return generic_permission(inode, mask);
3279 }
3280 
3281 static const struct inode_operations proc_tid_comm_inode_operations = {
3282 		.permission = proc_tid_comm_permission,
3283 };
3284 
3285 /*
3286  * Tasks
3287  */
3288 static const struct pid_entry tid_base_stuff[] = {
3289 	DIR("fd",        S_IRUSR|S_IXUSR, proc_fd_inode_operations, proc_fd_operations),
3290 	DIR("fdinfo",    S_IRUSR|S_IXUSR, proc_fdinfo_inode_operations, proc_fdinfo_operations),
3291 	DIR("ns",	 S_IRUSR|S_IXUGO, proc_ns_dir_inode_operations, proc_ns_dir_operations),
3292 #ifdef CONFIG_NET
3293 	DIR("net",        S_IRUGO|S_IXUGO, proc_net_inode_operations, proc_net_operations),
3294 #endif
3295 	REG("environ",   S_IRUSR, proc_environ_operations),
3296 	REG("auxv",      S_IRUSR, proc_auxv_operations),
3297 	ONE("status",    S_IRUGO, proc_pid_status),
3298 	ONE("personality", S_IRUSR, proc_pid_personality),
3299 	ONE("limits",	 S_IRUGO, proc_pid_limits),
3300 #ifdef CONFIG_SCHED_DEBUG
3301 	REG("sched",     S_IRUGO|S_IWUSR, proc_pid_sched_operations),
3302 #endif
3303 	NOD("comm",      S_IFREG|S_IRUGO|S_IWUSR,
3304 			 &proc_tid_comm_inode_operations,
3305 			 &proc_pid_set_comm_operations, {}),
3306 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
3307 	ONE("syscall",   S_IRUSR, proc_pid_syscall),
3308 #endif
3309 	REG("cmdline",   S_IRUGO, proc_pid_cmdline_ops),
3310 	ONE("stat",      S_IRUGO, proc_tid_stat),
3311 	ONE("statm",     S_IRUGO, proc_pid_statm),
3312 	REG("maps",      S_IRUGO, proc_tid_maps_operations),
3313 #ifdef CONFIG_PROC_CHILDREN
3314 	REG("children",  S_IRUGO, proc_tid_children_operations),
3315 #endif
3316 #ifdef CONFIG_NUMA
3317 	REG("numa_maps", S_IRUGO, proc_tid_numa_maps_operations),
3318 #endif
3319 	REG("mem",       S_IRUSR|S_IWUSR, proc_mem_operations),
3320 	LNK("cwd",       proc_cwd_link),
3321 	LNK("root",      proc_root_link),
3322 	LNK("exe",       proc_exe_link),
3323 	REG("mounts",    S_IRUGO, proc_mounts_operations),
3324 	REG("mountinfo",  S_IRUGO, proc_mountinfo_operations),
3325 #ifdef CONFIG_PROC_PAGE_MONITOR
3326 	REG("clear_refs", S_IWUSR, proc_clear_refs_operations),
3327 	REG("smaps",     S_IRUGO, proc_tid_smaps_operations),
3328 	REG("smaps_rollup", S_IRUGO, proc_pid_smaps_rollup_operations),
3329 	REG("pagemap",    S_IRUSR, proc_pagemap_operations),
3330 #endif
3331 #ifdef CONFIG_SECURITY
3332 	DIR("attr",      S_IRUGO|S_IXUGO, proc_attr_dir_inode_operations, proc_attr_dir_operations),
3333 #endif
3334 #ifdef CONFIG_KALLSYMS
3335 	ONE("wchan",     S_IRUGO, proc_pid_wchan),
3336 #endif
3337 #ifdef CONFIG_STACKTRACE
3338 	ONE("stack",      S_IRUSR, proc_pid_stack),
3339 #endif
3340 #ifdef CONFIG_SCHED_INFO
3341 	ONE("schedstat", S_IRUGO, proc_pid_schedstat),
3342 #endif
3343 #ifdef CONFIG_LATENCYTOP
3344 	REG("latency",  S_IRUGO, proc_lstats_operations),
3345 #endif
3346 #ifdef CONFIG_PROC_PID_CPUSET
3347 	ONE("cpuset",    S_IRUGO, proc_cpuset_show),
3348 #endif
3349 #ifdef CONFIG_CGROUPS
3350 	ONE("cgroup",  S_IRUGO, proc_cgroup_show),
3351 #endif
3352 	ONE("oom_score", S_IRUGO, proc_oom_score),
3353 	REG("oom_adj",   S_IRUGO|S_IWUSR, proc_oom_adj_operations),
3354 	REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
3355 #ifdef CONFIG_AUDITSYSCALL
3356 	REG("loginuid",  S_IWUSR|S_IRUGO, proc_loginuid_operations),
3357 	REG("sessionid",  S_IRUGO, proc_sessionid_operations),
3358 #endif
3359 #ifdef CONFIG_FAULT_INJECTION
3360 	REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
3361 	REG("fail-nth", 0644, proc_fail_nth_operations),
3362 #endif
3363 #ifdef CONFIG_TASK_IO_ACCOUNTING
3364 	ONE("io",	S_IRUSR, proc_tid_io_accounting),
3365 #endif
3366 #ifdef CONFIG_HARDWALL
3367 	ONE("hardwall",   S_IRUGO, proc_pid_hardwall),
3368 #endif
3369 #ifdef CONFIG_USER_NS
3370 	REG("uid_map",    S_IRUGO|S_IWUSR, proc_uid_map_operations),
3371 	REG("gid_map",    S_IRUGO|S_IWUSR, proc_gid_map_operations),
3372 	REG("projid_map", S_IRUGO|S_IWUSR, proc_projid_map_operations),
3373 	REG("setgroups",  S_IRUGO|S_IWUSR, proc_setgroups_operations),
3374 #endif
3375 #ifdef CONFIG_LIVEPATCH
3376 	ONE("patch_state",  S_IRUSR, proc_pid_patch_state),
3377 #endif
3378 };
3379 
3380 static int proc_tid_base_readdir(struct file *file, struct dir_context *ctx)
3381 {
3382 	return proc_pident_readdir(file, ctx,
3383 				   tid_base_stuff, ARRAY_SIZE(tid_base_stuff));
3384 }
3385 
3386 static struct dentry *proc_tid_base_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
3387 {
3388 	return proc_pident_lookup(dir, dentry,
3389 				  tid_base_stuff, ARRAY_SIZE(tid_base_stuff));
3390 }
3391 
3392 static const struct file_operations proc_tid_base_operations = {
3393 	.read		= generic_read_dir,
3394 	.iterate_shared	= proc_tid_base_readdir,
3395 	.llseek		= generic_file_llseek,
3396 };
3397 
3398 static const struct inode_operations proc_tid_base_inode_operations = {
3399 	.lookup		= proc_tid_base_lookup,
3400 	.getattr	= pid_getattr,
3401 	.setattr	= proc_setattr,
3402 };
3403 
3404 static int proc_task_instantiate(struct inode *dir,
3405 	struct dentry *dentry, struct task_struct *task, const void *ptr)
3406 {
3407 	struct inode *inode;
3408 	inode = proc_pid_make_inode(dir->i_sb, task, S_IFDIR | S_IRUGO | S_IXUGO);
3409 
3410 	if (!inode)
3411 		goto out;
3412 	inode->i_op = &proc_tid_base_inode_operations;
3413 	inode->i_fop = &proc_tid_base_operations;
3414 	inode->i_flags|=S_IMMUTABLE;
3415 
3416 	set_nlink(inode, nlink_tid);
3417 
3418 	d_set_d_op(dentry, &pid_dentry_operations);
3419 
3420 	d_add(dentry, inode);
3421 	/* Close the race of the process dying before we return the dentry */
3422 	if (pid_revalidate(dentry, 0))
3423 		return 0;
3424 out:
3425 	return -ENOENT;
3426 }
3427 
3428 static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)
3429 {
3430 	int result = -ENOENT;
3431 	struct task_struct *task;
3432 	struct task_struct *leader = get_proc_task(dir);
3433 	unsigned tid;
3434 	struct pid_namespace *ns;
3435 
3436 	if (!leader)
3437 		goto out_no_task;
3438 
3439 	tid = name_to_int(&dentry->d_name);
3440 	if (tid == ~0U)
3441 		goto out;
3442 
3443 	ns = dentry->d_sb->s_fs_info;
3444 	rcu_read_lock();
3445 	task = find_task_by_pid_ns(tid, ns);
3446 	if (task)
3447 		get_task_struct(task);
3448 	rcu_read_unlock();
3449 	if (!task)
3450 		goto out;
3451 	if (!same_thread_group(leader, task))
3452 		goto out_drop_task;
3453 
3454 	result = proc_task_instantiate(dir, dentry, task, NULL);
3455 out_drop_task:
3456 	put_task_struct(task);
3457 out:
3458 	put_task_struct(leader);
3459 out_no_task:
3460 	return ERR_PTR(result);
3461 }
3462 
3463 /*
3464  * Find the first tid of a thread group to return to user space.
3465  *
3466  * Usually this is just the thread group leader, but if the users
3467  * buffer was too small or there was a seek into the middle of the
3468  * directory we have more work todo.
3469  *
3470  * In the case of a short read we start with find_task_by_pid.
3471  *
3472  * In the case of a seek we start with the leader and walk nr
3473  * threads past it.
3474  */
3475 static struct task_struct *first_tid(struct pid *pid, int tid, loff_t f_pos,
3476 					struct pid_namespace *ns)
3477 {
3478 	struct task_struct *pos, *task;
3479 	unsigned long nr = f_pos;
3480 
3481 	if (nr != f_pos)	/* 32bit overflow? */
3482 		return NULL;
3483 
3484 	rcu_read_lock();
3485 	task = pid_task(pid, PIDTYPE_PID);
3486 	if (!task)
3487 		goto fail;
3488 
3489 	/* Attempt to start with the tid of a thread */
3490 	if (tid && nr) {
3491 		pos = find_task_by_pid_ns(tid, ns);
3492 		if (pos && same_thread_group(pos, task))
3493 			goto found;
3494 	}
3495 
3496 	/* If nr exceeds the number of threads there is nothing todo */
3497 	if (nr >= get_nr_threads(task))
3498 		goto fail;
3499 
3500 	/* If we haven't found our starting place yet start
3501 	 * with the leader and walk nr threads forward.
3502 	 */
3503 	pos = task = task->group_leader;
3504 	do {
3505 		if (!nr--)
3506 			goto found;
3507 	} while_each_thread(task, pos);
3508 fail:
3509 	pos = NULL;
3510 	goto out;
3511 found:
3512 	get_task_struct(pos);
3513 out:
3514 	rcu_read_unlock();
3515 	return pos;
3516 }
3517 
3518 /*
3519  * Find the next thread in the thread list.
3520  * Return NULL if there is an error or no next thread.
3521  *
3522  * The reference to the input task_struct is released.
3523  */
3524 static struct task_struct *next_tid(struct task_struct *start)
3525 {
3526 	struct task_struct *pos = NULL;
3527 	rcu_read_lock();
3528 	if (pid_alive(start)) {
3529 		pos = next_thread(start);
3530 		if (thread_group_leader(pos))
3531 			pos = NULL;
3532 		else
3533 			get_task_struct(pos);
3534 	}
3535 	rcu_read_unlock();
3536 	put_task_struct(start);
3537 	return pos;
3538 }
3539 
3540 /* for the /proc/TGID/task/ directories */
3541 static int proc_task_readdir(struct file *file, struct dir_context *ctx)
3542 {
3543 	struct inode *inode = file_inode(file);
3544 	struct task_struct *task;
3545 	struct pid_namespace *ns;
3546 	int tid;
3547 
3548 	if (proc_inode_is_dead(inode))
3549 		return -ENOENT;
3550 
3551 	if (!dir_emit_dots(file, ctx))
3552 		return 0;
3553 
3554 	/* f_version caches the tgid value that the last readdir call couldn't
3555 	 * return. lseek aka telldir automagically resets f_version to 0.
3556 	 */
3557 	ns = inode->i_sb->s_fs_info;
3558 	tid = (int)file->f_version;
3559 	file->f_version = 0;
3560 	for (task = first_tid(proc_pid(inode), tid, ctx->pos - 2, ns);
3561 	     task;
3562 	     task = next_tid(task), ctx->pos++) {
3563 		char name[PROC_NUMBUF];
3564 		int len;
3565 		tid = task_pid_nr_ns(task, ns);
3566 		len = snprintf(name, sizeof(name), "%d", tid);
3567 		if (!proc_fill_cache(file, ctx, name, len,
3568 				proc_task_instantiate, task, NULL)) {
3569 			/* returning this tgid failed, save it as the first
3570 			 * pid for the next readir call */
3571 			file->f_version = (u64)tid;
3572 			put_task_struct(task);
3573 			break;
3574 		}
3575 	}
3576 
3577 	return 0;
3578 }
3579 
3580 static int proc_task_getattr(const struct path *path, struct kstat *stat,
3581 			     u32 request_mask, unsigned int query_flags)
3582 {
3583 	struct inode *inode = d_inode(path->dentry);
3584 	struct task_struct *p = get_proc_task(inode);
3585 	generic_fillattr(inode, stat);
3586 
3587 	if (p) {
3588 		stat->nlink += get_nr_threads(p);
3589 		put_task_struct(p);
3590 	}
3591 
3592 	return 0;
3593 }
3594 
3595 static const struct inode_operations proc_task_inode_operations = {
3596 	.lookup		= proc_task_lookup,
3597 	.getattr	= proc_task_getattr,
3598 	.setattr	= proc_setattr,
3599 	.permission	= proc_pid_permission,
3600 };
3601 
3602 static const struct file_operations proc_task_operations = {
3603 	.read		= generic_read_dir,
3604 	.iterate_shared	= proc_task_readdir,
3605 	.llseek		= generic_file_llseek,
3606 };
3607 
3608 void __init set_proc_pid_nlink(void)
3609 {
3610 	nlink_tid = pid_entry_nlink(tid_base_stuff, ARRAY_SIZE(tid_base_stuff));
3611 	nlink_tgid = pid_entry_nlink(tgid_base_stuff, ARRAY_SIZE(tgid_base_stuff));
3612 }
3613