xref: /linux/fs/proc/base.c (revision 2624f124b3b5d550ab2fbef7ee3bc0e1fed09722)
1 /*
2  *  linux/fs/proc/base.c
3  *
4  *  Copyright (C) 1991, 1992 Linus Torvalds
5  *
6  *  proc base directory handling functions
7  *
8  *  1999, Al Viro. Rewritten. Now it covers the whole per-process part.
9  *  Instead of using magical inumbers to determine the kind of object
10  *  we allocate and fill in-core inodes upon lookup. They don't even
11  *  go into icache. We cache the reference to task_struct upon lookup too.
12  *  Eventually it should become a filesystem in its own. We don't use the
13  *  rest of procfs anymore.
14  *
15  *
16  *  Changelog:
17  *  17-Jan-2005
18  *  Allan Bezerra
19  *  Bruna Moreira <bruna.moreira@indt.org.br>
20  *  Edjard Mota <edjard.mota@indt.org.br>
21  *  Ilias Biris <ilias.biris@indt.org.br>
22  *  Mauricio Lin <mauricio.lin@indt.org.br>
23  *
24  *  Embedded Linux Lab - 10LE Instituto Nokia de Tecnologia - INdT
25  *
26  *  A new process specific entry (smaps) included in /proc. It shows the
27  *  size of rss for each memory area. The maps entry lacks information
28  *  about physical memory size (rss) for each mapped file, i.e.,
29  *  rss information for executables and library files.
30  *  This additional information is useful for any tools that need to know
31  *  about physical memory consumption for a process specific library.
32  *
33  *  Changelog:
34  *  21-Feb-2005
35  *  Embedded Linux Lab - 10LE Instituto Nokia de Tecnologia - INdT
36  *  Pud inclusion in the page table walking.
37  *
38  *  ChangeLog:
39  *  10-Mar-2005
40  *  10LE Instituto Nokia de Tecnologia - INdT:
41  *  A better way to walks through the page table as suggested by Hugh Dickins.
42  *
43  *  Simo Piiroinen <simo.piiroinen@nokia.com>:
44  *  Smaps information related to shared, private, clean and dirty pages.
45  *
46  *  Paul Mundt <paul.mundt@nokia.com>:
47  *  Overall revision about smaps.
48  */
49 
50 #include <asm/uaccess.h>
51 
52 #include <linux/config.h>
53 #include <linux/errno.h>
54 #include <linux/time.h>
55 #include <linux/proc_fs.h>
56 #include <linux/stat.h>
57 #include <linux/init.h>
58 #include <linux/file.h>
59 #include <linux/string.h>
60 #include <linux/seq_file.h>
61 #include <linux/namei.h>
62 #include <linux/namespace.h>
63 #include <linux/mm.h>
64 #include <linux/smp_lock.h>
65 #include <linux/kallsyms.h>
66 #include <linux/mount.h>
67 #include <linux/security.h>
68 #include <linux/ptrace.h>
69 #include <linux/seccomp.h>
70 #include <linux/cpuset.h>
71 #include <linux/audit.h>
72 #include "internal.h"
73 
74 /*
75  * For hysterical raisins we keep the same inumbers as in the old procfs.
76  * Feel free to change the macro below - just keep the range distinct from
77  * inumbers of the rest of procfs (currently those are in 0x0000--0xffff).
78  * As soon as we'll get a separate superblock we will be able to forget
79  * about magical ranges too.
80  */
81 
82 #define fake_ino(pid,ino) (((pid)<<16)|(ino))
83 
84 enum pid_directory_inos {
85 	PROC_TGID_INO = 2,
86 	PROC_TGID_TASK,
87 	PROC_TGID_STATUS,
88 	PROC_TGID_MEM,
89 #ifdef CONFIG_SECCOMP
90 	PROC_TGID_SECCOMP,
91 #endif
92 	PROC_TGID_CWD,
93 	PROC_TGID_ROOT,
94 	PROC_TGID_EXE,
95 	PROC_TGID_FD,
96 	PROC_TGID_ENVIRON,
97 	PROC_TGID_AUXV,
98 	PROC_TGID_CMDLINE,
99 	PROC_TGID_STAT,
100 	PROC_TGID_STATM,
101 	PROC_TGID_MAPS,
102 	PROC_TGID_NUMA_MAPS,
103 	PROC_TGID_MOUNTS,
104 	PROC_TGID_WCHAN,
105 	PROC_TGID_SMAPS,
106 #ifdef CONFIG_SCHEDSTATS
107 	PROC_TGID_SCHEDSTAT,
108 #endif
109 #ifdef CONFIG_CPUSETS
110 	PROC_TGID_CPUSET,
111 #endif
112 #ifdef CONFIG_SECURITY
113 	PROC_TGID_ATTR,
114 	PROC_TGID_ATTR_CURRENT,
115 	PROC_TGID_ATTR_PREV,
116 	PROC_TGID_ATTR_EXEC,
117 	PROC_TGID_ATTR_FSCREATE,
118 #endif
119 #ifdef CONFIG_AUDITSYSCALL
120 	PROC_TGID_LOGINUID,
121 #endif
122 	PROC_TGID_OOM_SCORE,
123 	PROC_TGID_OOM_ADJUST,
124 	PROC_TID_INO,
125 	PROC_TID_STATUS,
126 	PROC_TID_MEM,
127 #ifdef CONFIG_SECCOMP
128 	PROC_TID_SECCOMP,
129 #endif
130 	PROC_TID_CWD,
131 	PROC_TID_ROOT,
132 	PROC_TID_EXE,
133 	PROC_TID_FD,
134 	PROC_TID_ENVIRON,
135 	PROC_TID_AUXV,
136 	PROC_TID_CMDLINE,
137 	PROC_TID_STAT,
138 	PROC_TID_STATM,
139 	PROC_TID_MAPS,
140 	PROC_TID_NUMA_MAPS,
141 	PROC_TID_MOUNTS,
142 	PROC_TID_WCHAN,
143 	PROC_TID_SMAPS,
144 #ifdef CONFIG_SCHEDSTATS
145 	PROC_TID_SCHEDSTAT,
146 #endif
147 #ifdef CONFIG_CPUSETS
148 	PROC_TID_CPUSET,
149 #endif
150 #ifdef CONFIG_SECURITY
151 	PROC_TID_ATTR,
152 	PROC_TID_ATTR_CURRENT,
153 	PROC_TID_ATTR_PREV,
154 	PROC_TID_ATTR_EXEC,
155 	PROC_TID_ATTR_FSCREATE,
156 #endif
157 #ifdef CONFIG_AUDITSYSCALL
158 	PROC_TID_LOGINUID,
159 #endif
160 	PROC_TID_OOM_SCORE,
161 	PROC_TID_OOM_ADJUST,
162 
163 	/* Add new entries before this */
164 	PROC_TID_FD_DIR = 0x8000,	/* 0x8000-0xffff */
165 };
166 
167 struct pid_entry {
168 	int type;
169 	int len;
170 	char *name;
171 	mode_t mode;
172 };
173 
174 #define E(type,name,mode) {(type),sizeof(name)-1,(name),(mode)}
175 
176 static struct pid_entry tgid_base_stuff[] = {
177 	E(PROC_TGID_TASK,      "task",    S_IFDIR|S_IRUGO|S_IXUGO),
178 	E(PROC_TGID_FD,        "fd",      S_IFDIR|S_IRUSR|S_IXUSR),
179 	E(PROC_TGID_ENVIRON,   "environ", S_IFREG|S_IRUSR),
180 	E(PROC_TGID_AUXV,      "auxv",	  S_IFREG|S_IRUSR),
181 	E(PROC_TGID_STATUS,    "status",  S_IFREG|S_IRUGO),
182 	E(PROC_TGID_CMDLINE,   "cmdline", S_IFREG|S_IRUGO),
183 	E(PROC_TGID_STAT,      "stat",    S_IFREG|S_IRUGO),
184 	E(PROC_TGID_STATM,     "statm",   S_IFREG|S_IRUGO),
185 	E(PROC_TGID_MAPS,      "maps",    S_IFREG|S_IRUGO),
186 #ifdef CONFIG_NUMA
187 	E(PROC_TGID_NUMA_MAPS, "numa_maps", S_IFREG|S_IRUGO),
188 #endif
189 	E(PROC_TGID_MEM,       "mem",     S_IFREG|S_IRUSR|S_IWUSR),
190 #ifdef CONFIG_SECCOMP
191 	E(PROC_TGID_SECCOMP,   "seccomp", S_IFREG|S_IRUSR|S_IWUSR),
192 #endif
193 	E(PROC_TGID_CWD,       "cwd",     S_IFLNK|S_IRWXUGO),
194 	E(PROC_TGID_ROOT,      "root",    S_IFLNK|S_IRWXUGO),
195 	E(PROC_TGID_EXE,       "exe",     S_IFLNK|S_IRWXUGO),
196 	E(PROC_TGID_MOUNTS,    "mounts",  S_IFREG|S_IRUGO),
197 	E(PROC_TGID_SMAPS,     "smaps",   S_IFREG|S_IRUGO),
198 #ifdef CONFIG_SECURITY
199 	E(PROC_TGID_ATTR,      "attr",    S_IFDIR|S_IRUGO|S_IXUGO),
200 #endif
201 #ifdef CONFIG_KALLSYMS
202 	E(PROC_TGID_WCHAN,     "wchan",   S_IFREG|S_IRUGO),
203 #endif
204 #ifdef CONFIG_SCHEDSTATS
205 	E(PROC_TGID_SCHEDSTAT, "schedstat", S_IFREG|S_IRUGO),
206 #endif
207 #ifdef CONFIG_CPUSETS
208 	E(PROC_TGID_CPUSET,    "cpuset",  S_IFREG|S_IRUGO),
209 #endif
210 	E(PROC_TGID_OOM_SCORE, "oom_score",S_IFREG|S_IRUGO),
211 	E(PROC_TGID_OOM_ADJUST,"oom_adj", S_IFREG|S_IRUGO|S_IWUSR),
212 #ifdef CONFIG_AUDITSYSCALL
213 	E(PROC_TGID_LOGINUID, "loginuid", S_IFREG|S_IWUSR|S_IRUGO),
214 #endif
215 	{0,0,NULL,0}
216 };
217 static struct pid_entry tid_base_stuff[] = {
218 	E(PROC_TID_FD,         "fd",      S_IFDIR|S_IRUSR|S_IXUSR),
219 	E(PROC_TID_ENVIRON,    "environ", S_IFREG|S_IRUSR),
220 	E(PROC_TID_AUXV,       "auxv",	  S_IFREG|S_IRUSR),
221 	E(PROC_TID_STATUS,     "status",  S_IFREG|S_IRUGO),
222 	E(PROC_TID_CMDLINE,    "cmdline", S_IFREG|S_IRUGO),
223 	E(PROC_TID_STAT,       "stat",    S_IFREG|S_IRUGO),
224 	E(PROC_TID_STATM,      "statm",   S_IFREG|S_IRUGO),
225 	E(PROC_TID_MAPS,       "maps",    S_IFREG|S_IRUGO),
226 #ifdef CONFIG_NUMA
227 	E(PROC_TID_NUMA_MAPS,  "numa_maps",    S_IFREG|S_IRUGO),
228 #endif
229 	E(PROC_TID_MEM,        "mem",     S_IFREG|S_IRUSR|S_IWUSR),
230 #ifdef CONFIG_SECCOMP
231 	E(PROC_TID_SECCOMP,    "seccomp", S_IFREG|S_IRUSR|S_IWUSR),
232 #endif
233 	E(PROC_TID_CWD,        "cwd",     S_IFLNK|S_IRWXUGO),
234 	E(PROC_TID_ROOT,       "root",    S_IFLNK|S_IRWXUGO),
235 	E(PROC_TID_EXE,        "exe",     S_IFLNK|S_IRWXUGO),
236 	E(PROC_TID_MOUNTS,     "mounts",  S_IFREG|S_IRUGO),
237 	E(PROC_TID_SMAPS,      "smaps",   S_IFREG|S_IRUGO),
238 #ifdef CONFIG_SECURITY
239 	E(PROC_TID_ATTR,       "attr",    S_IFDIR|S_IRUGO|S_IXUGO),
240 #endif
241 #ifdef CONFIG_KALLSYMS
242 	E(PROC_TID_WCHAN,      "wchan",   S_IFREG|S_IRUGO),
243 #endif
244 #ifdef CONFIG_SCHEDSTATS
245 	E(PROC_TID_SCHEDSTAT, "schedstat",S_IFREG|S_IRUGO),
246 #endif
247 #ifdef CONFIG_CPUSETS
248 	E(PROC_TID_CPUSET,     "cpuset",  S_IFREG|S_IRUGO),
249 #endif
250 	E(PROC_TID_OOM_SCORE,  "oom_score",S_IFREG|S_IRUGO),
251 	E(PROC_TID_OOM_ADJUST, "oom_adj", S_IFREG|S_IRUGO|S_IWUSR),
252 #ifdef CONFIG_AUDITSYSCALL
253 	E(PROC_TID_LOGINUID, "loginuid", S_IFREG|S_IWUSR|S_IRUGO),
254 #endif
255 	{0,0,NULL,0}
256 };
257 
258 #ifdef CONFIG_SECURITY
259 static struct pid_entry tgid_attr_stuff[] = {
260 	E(PROC_TGID_ATTR_CURRENT,  "current",  S_IFREG|S_IRUGO|S_IWUGO),
261 	E(PROC_TGID_ATTR_PREV,     "prev",     S_IFREG|S_IRUGO),
262 	E(PROC_TGID_ATTR_EXEC,     "exec",     S_IFREG|S_IRUGO|S_IWUGO),
263 	E(PROC_TGID_ATTR_FSCREATE, "fscreate", S_IFREG|S_IRUGO|S_IWUGO),
264 	{0,0,NULL,0}
265 };
266 static struct pid_entry tid_attr_stuff[] = {
267 	E(PROC_TID_ATTR_CURRENT,   "current",  S_IFREG|S_IRUGO|S_IWUGO),
268 	E(PROC_TID_ATTR_PREV,      "prev",     S_IFREG|S_IRUGO),
269 	E(PROC_TID_ATTR_EXEC,      "exec",     S_IFREG|S_IRUGO|S_IWUGO),
270 	E(PROC_TID_ATTR_FSCREATE,  "fscreate", S_IFREG|S_IRUGO|S_IWUGO),
271 	{0,0,NULL,0}
272 };
273 #endif
274 
275 #undef E
276 
277 static int proc_fd_link(struct inode *inode, struct dentry **dentry, struct vfsmount **mnt)
278 {
279 	struct task_struct *task = proc_task(inode);
280 	struct files_struct *files;
281 	struct file *file;
282 	int fd = proc_type(inode) - PROC_TID_FD_DIR;
283 
284 	files = get_files_struct(task);
285 	if (files) {
286 		spin_lock(&files->file_lock);
287 		file = fcheck_files(files, fd);
288 		if (file) {
289 			*mnt = mntget(file->f_vfsmnt);
290 			*dentry = dget(file->f_dentry);
291 			spin_unlock(&files->file_lock);
292 			put_files_struct(files);
293 			return 0;
294 		}
295 		spin_unlock(&files->file_lock);
296 		put_files_struct(files);
297 	}
298 	return -ENOENT;
299 }
300 
301 static struct fs_struct *get_fs_struct(struct task_struct *task)
302 {
303 	struct fs_struct *fs;
304 	task_lock(task);
305 	fs = task->fs;
306 	if(fs)
307 		atomic_inc(&fs->count);
308 	task_unlock(task);
309 	return fs;
310 }
311 
312 static int proc_cwd_link(struct inode *inode, struct dentry **dentry, struct vfsmount **mnt)
313 {
314 	struct fs_struct *fs = get_fs_struct(proc_task(inode));
315 	int result = -ENOENT;
316 	if (fs) {
317 		read_lock(&fs->lock);
318 		*mnt = mntget(fs->pwdmnt);
319 		*dentry = dget(fs->pwd);
320 		read_unlock(&fs->lock);
321 		result = 0;
322 		put_fs_struct(fs);
323 	}
324 	return result;
325 }
326 
327 static int proc_root_link(struct inode *inode, struct dentry **dentry, struct vfsmount **mnt)
328 {
329 	struct fs_struct *fs = get_fs_struct(proc_task(inode));
330 	int result = -ENOENT;
331 	if (fs) {
332 		read_lock(&fs->lock);
333 		*mnt = mntget(fs->rootmnt);
334 		*dentry = dget(fs->root);
335 		read_unlock(&fs->lock);
336 		result = 0;
337 		put_fs_struct(fs);
338 	}
339 	return result;
340 }
341 
342 #define MAY_PTRACE(task) \
343 	(task == current || \
344 	(task->parent == current && \
345 	(task->ptrace & PT_PTRACED) && \
346 	 (task->state == TASK_STOPPED || task->state == TASK_TRACED) && \
347 	 security_ptrace(current,task) == 0))
348 
349 static int proc_pid_environ(struct task_struct *task, char * buffer)
350 {
351 	int res = 0;
352 	struct mm_struct *mm = get_task_mm(task);
353 	if (mm) {
354 		unsigned int len = mm->env_end - mm->env_start;
355 		if (len > PAGE_SIZE)
356 			len = PAGE_SIZE;
357 		res = access_process_vm(task, mm->env_start, buffer, len, 0);
358 		if (!ptrace_may_attach(task))
359 			res = -ESRCH;
360 		mmput(mm);
361 	}
362 	return res;
363 }
364 
365 static int proc_pid_cmdline(struct task_struct *task, char * buffer)
366 {
367 	int res = 0;
368 	unsigned int len;
369 	struct mm_struct *mm = get_task_mm(task);
370 	if (!mm)
371 		goto out;
372 	if (!mm->arg_end)
373 		goto out_mm;	/* Shh! No looking before we're done */
374 
375  	len = mm->arg_end - mm->arg_start;
376 
377 	if (len > PAGE_SIZE)
378 		len = PAGE_SIZE;
379 
380 	res = access_process_vm(task, mm->arg_start, buffer, len, 0);
381 
382 	// If the nul at the end of args has been overwritten, then
383 	// assume application is using setproctitle(3).
384 	if (res > 0 && buffer[res-1] != '\0' && len < PAGE_SIZE) {
385 		len = strnlen(buffer, res);
386 		if (len < res) {
387 		    res = len;
388 		} else {
389 			len = mm->env_end - mm->env_start;
390 			if (len > PAGE_SIZE - res)
391 				len = PAGE_SIZE - res;
392 			res += access_process_vm(task, mm->env_start, buffer+res, len, 0);
393 			res = strnlen(buffer, res);
394 		}
395 	}
396 out_mm:
397 	mmput(mm);
398 out:
399 	return res;
400 }
401 
402 static int proc_pid_auxv(struct task_struct *task, char *buffer)
403 {
404 	int res = 0;
405 	struct mm_struct *mm = get_task_mm(task);
406 	if (mm) {
407 		unsigned int nwords = 0;
408 		do
409 			nwords += 2;
410 		while (mm->saved_auxv[nwords - 2] != 0); /* AT_NULL */
411 		res = nwords * sizeof(mm->saved_auxv[0]);
412 		if (res > PAGE_SIZE)
413 			res = PAGE_SIZE;
414 		memcpy(buffer, mm->saved_auxv, res);
415 		mmput(mm);
416 	}
417 	return res;
418 }
419 
420 
421 #ifdef CONFIG_KALLSYMS
422 /*
423  * Provides a wchan file via kallsyms in a proper one-value-per-file format.
424  * Returns the resolved symbol.  If that fails, simply return the address.
425  */
426 static int proc_pid_wchan(struct task_struct *task, char *buffer)
427 {
428 	char *modname;
429 	const char *sym_name;
430 	unsigned long wchan, size, offset;
431 	char namebuf[KSYM_NAME_LEN+1];
432 
433 	wchan = get_wchan(task);
434 
435 	sym_name = kallsyms_lookup(wchan, &size, &offset, &modname, namebuf);
436 	if (sym_name)
437 		return sprintf(buffer, "%s", sym_name);
438 	return sprintf(buffer, "%lu", wchan);
439 }
440 #endif /* CONFIG_KALLSYMS */
441 
442 #ifdef CONFIG_SCHEDSTATS
443 /*
444  * Provides /proc/PID/schedstat
445  */
446 static int proc_pid_schedstat(struct task_struct *task, char *buffer)
447 {
448 	return sprintf(buffer, "%lu %lu %lu\n",
449 			task->sched_info.cpu_time,
450 			task->sched_info.run_delay,
451 			task->sched_info.pcnt);
452 }
453 #endif
454 
455 /* The badness from the OOM killer */
456 unsigned long badness(struct task_struct *p, unsigned long uptime);
457 static int proc_oom_score(struct task_struct *task, char *buffer)
458 {
459 	unsigned long points;
460 	struct timespec uptime;
461 
462 	do_posix_clock_monotonic_gettime(&uptime);
463 	points = badness(task, uptime.tv_sec);
464 	return sprintf(buffer, "%lu\n", points);
465 }
466 
467 /************************************************************************/
468 /*                       Here the fs part begins                        */
469 /************************************************************************/
470 
471 /* permission checks */
472 
473 static int proc_check_root(struct inode *inode)
474 {
475 	struct dentry *de, *base, *root;
476 	struct vfsmount *our_vfsmnt, *vfsmnt, *mnt;
477 	int res = 0;
478 
479 	if (proc_root_link(inode, &root, &vfsmnt)) /* Ewww... */
480 		return -ENOENT;
481 	read_lock(&current->fs->lock);
482 	our_vfsmnt = mntget(current->fs->rootmnt);
483 	base = dget(current->fs->root);
484 	read_unlock(&current->fs->lock);
485 
486 	spin_lock(&vfsmount_lock);
487 	de = root;
488 	mnt = vfsmnt;
489 
490 	while (vfsmnt != our_vfsmnt) {
491 		if (vfsmnt == vfsmnt->mnt_parent)
492 			goto out;
493 		de = vfsmnt->mnt_mountpoint;
494 		vfsmnt = vfsmnt->mnt_parent;
495 	}
496 
497 	if (!is_subdir(de, base))
498 		goto out;
499 	spin_unlock(&vfsmount_lock);
500 
501 exit:
502 	dput(base);
503 	mntput(our_vfsmnt);
504 	dput(root);
505 	mntput(mnt);
506 	return res;
507 out:
508 	spin_unlock(&vfsmount_lock);
509 	res = -EACCES;
510 	goto exit;
511 }
512 
513 static int proc_permission(struct inode *inode, int mask, struct nameidata *nd)
514 {
515 	if (generic_permission(inode, mask, NULL) != 0)
516 		return -EACCES;
517 	return proc_check_root(inode);
518 }
519 
520 extern struct seq_operations proc_pid_maps_op;
521 static int maps_open(struct inode *inode, struct file *file)
522 {
523 	struct task_struct *task = proc_task(inode);
524 	int ret = seq_open(file, &proc_pid_maps_op);
525 	if (!ret) {
526 		struct seq_file *m = file->private_data;
527 		m->private = task;
528 	}
529 	return ret;
530 }
531 
532 static struct file_operations proc_maps_operations = {
533 	.open		= maps_open,
534 	.read		= seq_read,
535 	.llseek		= seq_lseek,
536 	.release	= seq_release,
537 };
538 
539 #ifdef CONFIG_NUMA
540 extern struct seq_operations proc_pid_numa_maps_op;
541 static int numa_maps_open(struct inode *inode, struct file *file)
542 {
543 	struct task_struct *task = proc_task(inode);
544 	int ret = seq_open(file, &proc_pid_numa_maps_op);
545 	if (!ret) {
546 		struct seq_file *m = file->private_data;
547 		m->private = task;
548 	}
549 	return ret;
550 }
551 
552 static struct file_operations proc_numa_maps_operations = {
553 	.open		= numa_maps_open,
554 	.read		= seq_read,
555 	.llseek		= seq_lseek,
556 	.release	= seq_release,
557 };
558 #endif
559 
560 extern struct seq_operations proc_pid_smaps_op;
561 static int smaps_open(struct inode *inode, struct file *file)
562 {
563 	struct task_struct *task = proc_task(inode);
564 	int ret = seq_open(file, &proc_pid_smaps_op);
565 	if (!ret) {
566 		struct seq_file *m = file->private_data;
567 		m->private = task;
568 	}
569 	return ret;
570 }
571 
572 static struct file_operations proc_smaps_operations = {
573 	.open		= smaps_open,
574 	.read		= seq_read,
575 	.llseek		= seq_lseek,
576 	.release	= seq_release,
577 };
578 
579 extern struct seq_operations mounts_op;
580 static int mounts_open(struct inode *inode, struct file *file)
581 {
582 	struct task_struct *task = proc_task(inode);
583 	int ret = seq_open(file, &mounts_op);
584 
585 	if (!ret) {
586 		struct seq_file *m = file->private_data;
587 		struct namespace *namespace;
588 		task_lock(task);
589 		namespace = task->namespace;
590 		if (namespace)
591 			get_namespace(namespace);
592 		task_unlock(task);
593 
594 		if (namespace)
595 			m->private = namespace;
596 		else {
597 			seq_release(inode, file);
598 			ret = -EINVAL;
599 		}
600 	}
601 	return ret;
602 }
603 
604 static int mounts_release(struct inode *inode, struct file *file)
605 {
606 	struct seq_file *m = file->private_data;
607 	struct namespace *namespace = m->private;
608 	put_namespace(namespace);
609 	return seq_release(inode, file);
610 }
611 
612 static struct file_operations proc_mounts_operations = {
613 	.open		= mounts_open,
614 	.read		= seq_read,
615 	.llseek		= seq_lseek,
616 	.release	= mounts_release,
617 };
618 
619 #define PROC_BLOCK_SIZE	(3*1024)		/* 4K page size but our output routines use some slack for overruns */
620 
621 static ssize_t proc_info_read(struct file * file, char __user * buf,
622 			  size_t count, loff_t *ppos)
623 {
624 	struct inode * inode = file->f_dentry->d_inode;
625 	unsigned long page;
626 	ssize_t length;
627 	struct task_struct *task = proc_task(inode);
628 
629 	if (count > PROC_BLOCK_SIZE)
630 		count = PROC_BLOCK_SIZE;
631 	if (!(page = __get_free_page(GFP_KERNEL)))
632 		return -ENOMEM;
633 
634 	length = PROC_I(inode)->op.proc_read(task, (char*)page);
635 
636 	if (length >= 0)
637 		length = simple_read_from_buffer(buf, count, ppos, (char *)page, length);
638 	free_page(page);
639 	return length;
640 }
641 
642 static struct file_operations proc_info_file_operations = {
643 	.read		= proc_info_read,
644 };
645 
646 static int mem_open(struct inode* inode, struct file* file)
647 {
648 	file->private_data = (void*)((long)current->self_exec_id);
649 	return 0;
650 }
651 
652 static ssize_t mem_read(struct file * file, char __user * buf,
653 			size_t count, loff_t *ppos)
654 {
655 	struct task_struct *task = proc_task(file->f_dentry->d_inode);
656 	char *page;
657 	unsigned long src = *ppos;
658 	int ret = -ESRCH;
659 	struct mm_struct *mm;
660 
661 	if (!MAY_PTRACE(task) || !ptrace_may_attach(task))
662 		goto out;
663 
664 	ret = -ENOMEM;
665 	page = (char *)__get_free_page(GFP_USER);
666 	if (!page)
667 		goto out;
668 
669 	ret = 0;
670 
671 	mm = get_task_mm(task);
672 	if (!mm)
673 		goto out_free;
674 
675 	ret = -EIO;
676 
677 	if (file->private_data != (void*)((long)current->self_exec_id))
678 		goto out_put;
679 
680 	ret = 0;
681 
682 	while (count > 0) {
683 		int this_len, retval;
684 
685 		this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
686 		retval = access_process_vm(task, src, page, this_len, 0);
687 		if (!retval || !MAY_PTRACE(task) || !ptrace_may_attach(task)) {
688 			if (!ret)
689 				ret = -EIO;
690 			break;
691 		}
692 
693 		if (copy_to_user(buf, page, retval)) {
694 			ret = -EFAULT;
695 			break;
696 		}
697 
698 		ret += retval;
699 		src += retval;
700 		buf += retval;
701 		count -= retval;
702 	}
703 	*ppos = src;
704 
705 out_put:
706 	mmput(mm);
707 out_free:
708 	free_page((unsigned long) page);
709 out:
710 	return ret;
711 }
712 
713 #define mem_write NULL
714 
715 #ifndef mem_write
716 /* This is a security hazard */
717 static ssize_t mem_write(struct file * file, const char * buf,
718 			 size_t count, loff_t *ppos)
719 {
720 	int copied = 0;
721 	char *page;
722 	struct task_struct *task = proc_task(file->f_dentry->d_inode);
723 	unsigned long dst = *ppos;
724 
725 	if (!MAY_PTRACE(task) || !ptrace_may_attach(task))
726 		return -ESRCH;
727 
728 	page = (char *)__get_free_page(GFP_USER);
729 	if (!page)
730 		return -ENOMEM;
731 
732 	while (count > 0) {
733 		int this_len, retval;
734 
735 		this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
736 		if (copy_from_user(page, buf, this_len)) {
737 			copied = -EFAULT;
738 			break;
739 		}
740 		retval = access_process_vm(task, dst, page, this_len, 1);
741 		if (!retval) {
742 			if (!copied)
743 				copied = -EIO;
744 			break;
745 		}
746 		copied += retval;
747 		buf += retval;
748 		dst += retval;
749 		count -= retval;
750 	}
751 	*ppos = dst;
752 	free_page((unsigned long) page);
753 	return copied;
754 }
755 #endif
756 
757 static loff_t mem_lseek(struct file * file, loff_t offset, int orig)
758 {
759 	switch (orig) {
760 	case 0:
761 		file->f_pos = offset;
762 		break;
763 	case 1:
764 		file->f_pos += offset;
765 		break;
766 	default:
767 		return -EINVAL;
768 	}
769 	force_successful_syscall_return();
770 	return file->f_pos;
771 }
772 
773 static struct file_operations proc_mem_operations = {
774 	.llseek		= mem_lseek,
775 	.read		= mem_read,
776 	.write		= mem_write,
777 	.open		= mem_open,
778 };
779 
780 static ssize_t oom_adjust_read(struct file *file, char __user *buf,
781 				size_t count, loff_t *ppos)
782 {
783 	struct task_struct *task = proc_task(file->f_dentry->d_inode);
784 	char buffer[8];
785 	size_t len;
786 	int oom_adjust = task->oomkilladj;
787 	loff_t __ppos = *ppos;
788 
789 	len = sprintf(buffer, "%i\n", oom_adjust);
790 	if (__ppos >= len)
791 		return 0;
792 	if (count > len-__ppos)
793 		count = len-__ppos;
794 	if (copy_to_user(buf, buffer + __ppos, count))
795 		return -EFAULT;
796 	*ppos = __ppos + count;
797 	return count;
798 }
799 
800 static ssize_t oom_adjust_write(struct file *file, const char __user *buf,
801 				size_t count, loff_t *ppos)
802 {
803 	struct task_struct *task = proc_task(file->f_dentry->d_inode);
804 	char buffer[8], *end;
805 	int oom_adjust;
806 
807 	if (!capable(CAP_SYS_RESOURCE))
808 		return -EPERM;
809 	memset(buffer, 0, 8);
810 	if (count > 6)
811 		count = 6;
812 	if (copy_from_user(buffer, buf, count))
813 		return -EFAULT;
814 	oom_adjust = simple_strtol(buffer, &end, 0);
815 	if ((oom_adjust < -16 || oom_adjust > 15) && oom_adjust != OOM_DISABLE)
816 		return -EINVAL;
817 	if (*end == '\n')
818 		end++;
819 	task->oomkilladj = oom_adjust;
820 	if (end - buffer == 0)
821 		return -EIO;
822 	return end - buffer;
823 }
824 
825 static struct file_operations proc_oom_adjust_operations = {
826 	.read		= oom_adjust_read,
827 	.write		= oom_adjust_write,
828 };
829 
830 static struct inode_operations proc_mem_inode_operations = {
831 	.permission	= proc_permission,
832 };
833 
834 #ifdef CONFIG_AUDITSYSCALL
835 #define TMPBUFLEN 21
836 static ssize_t proc_loginuid_read(struct file * file, char __user * buf,
837 				  size_t count, loff_t *ppos)
838 {
839 	struct inode * inode = file->f_dentry->d_inode;
840 	struct task_struct *task = proc_task(inode);
841 	ssize_t length;
842 	char tmpbuf[TMPBUFLEN];
843 
844 	length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
845 				audit_get_loginuid(task->audit_context));
846 	return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
847 }
848 
849 static ssize_t proc_loginuid_write(struct file * file, const char __user * buf,
850 				   size_t count, loff_t *ppos)
851 {
852 	struct inode * inode = file->f_dentry->d_inode;
853 	char *page, *tmp;
854 	ssize_t length;
855 	struct task_struct *task = proc_task(inode);
856 	uid_t loginuid;
857 
858 	if (!capable(CAP_AUDIT_CONTROL))
859 		return -EPERM;
860 
861 	if (current != task)
862 		return -EPERM;
863 
864 	if (count > PAGE_SIZE)
865 		count = PAGE_SIZE;
866 
867 	if (*ppos != 0) {
868 		/* No partial writes. */
869 		return -EINVAL;
870 	}
871 	page = (char*)__get_free_page(GFP_USER);
872 	if (!page)
873 		return -ENOMEM;
874 	length = -EFAULT;
875 	if (copy_from_user(page, buf, count))
876 		goto out_free_page;
877 
878 	loginuid = simple_strtoul(page, &tmp, 10);
879 	if (tmp == page) {
880 		length = -EINVAL;
881 		goto out_free_page;
882 
883 	}
884 	length = audit_set_loginuid(task, loginuid);
885 	if (likely(length == 0))
886 		length = count;
887 
888 out_free_page:
889 	free_page((unsigned long) page);
890 	return length;
891 }
892 
893 static struct file_operations proc_loginuid_operations = {
894 	.read		= proc_loginuid_read,
895 	.write		= proc_loginuid_write,
896 };
897 #endif
898 
899 #ifdef CONFIG_SECCOMP
900 static ssize_t seccomp_read(struct file *file, char __user *buf,
901 			    size_t count, loff_t *ppos)
902 {
903 	struct task_struct *tsk = proc_task(file->f_dentry->d_inode);
904 	char __buf[20];
905 	loff_t __ppos = *ppos;
906 	size_t len;
907 
908 	/* no need to print the trailing zero, so use only len */
909 	len = sprintf(__buf, "%u\n", tsk->seccomp.mode);
910 	if (__ppos >= len)
911 		return 0;
912 	if (count > len - __ppos)
913 		count = len - __ppos;
914 	if (copy_to_user(buf, __buf + __ppos, count))
915 		return -EFAULT;
916 	*ppos = __ppos + count;
917 	return count;
918 }
919 
920 static ssize_t seccomp_write(struct file *file, const char __user *buf,
921 			     size_t count, loff_t *ppos)
922 {
923 	struct task_struct *tsk = proc_task(file->f_dentry->d_inode);
924 	char __buf[20], *end;
925 	unsigned int seccomp_mode;
926 
927 	/* can set it only once to be even more secure */
928 	if (unlikely(tsk->seccomp.mode))
929 		return -EPERM;
930 
931 	memset(__buf, 0, sizeof(__buf));
932 	count = min(count, sizeof(__buf) - 1);
933 	if (copy_from_user(__buf, buf, count))
934 		return -EFAULT;
935 	seccomp_mode = simple_strtoul(__buf, &end, 0);
936 	if (*end == '\n')
937 		end++;
938 	if (seccomp_mode && seccomp_mode <= NR_SECCOMP_MODES) {
939 		tsk->seccomp.mode = seccomp_mode;
940 		set_tsk_thread_flag(tsk, TIF_SECCOMP);
941 	} else
942 		return -EINVAL;
943 	if (unlikely(!(end - __buf)))
944 		return -EIO;
945 	return end - __buf;
946 }
947 
948 static struct file_operations proc_seccomp_operations = {
949 	.read		= seccomp_read,
950 	.write		= seccomp_write,
951 };
952 #endif /* CONFIG_SECCOMP */
953 
954 static void *proc_pid_follow_link(struct dentry *dentry, struct nameidata *nd)
955 {
956 	struct inode *inode = dentry->d_inode;
957 	int error = -EACCES;
958 
959 	/* We don't need a base pointer in the /proc filesystem */
960 	path_release(nd);
961 
962 	if (current->fsuid != inode->i_uid && !capable(CAP_DAC_OVERRIDE))
963 		goto out;
964 	error = proc_check_root(inode);
965 	if (error)
966 		goto out;
967 
968 	error = PROC_I(inode)->op.proc_get_link(inode, &nd->dentry, &nd->mnt);
969 	nd->last_type = LAST_BIND;
970 out:
971 	return ERR_PTR(error);
972 }
973 
974 static int do_proc_readlink(struct dentry *dentry, struct vfsmount *mnt,
975 			    char __user *buffer, int buflen)
976 {
977 	struct inode * inode;
978 	char *tmp = (char*)__get_free_page(GFP_KERNEL), *path;
979 	int len;
980 
981 	if (!tmp)
982 		return -ENOMEM;
983 
984 	inode = dentry->d_inode;
985 	path = d_path(dentry, mnt, tmp, PAGE_SIZE);
986 	len = PTR_ERR(path);
987 	if (IS_ERR(path))
988 		goto out;
989 	len = tmp + PAGE_SIZE - 1 - path;
990 
991 	if (len > buflen)
992 		len = buflen;
993 	if (copy_to_user(buffer, path, len))
994 		len = -EFAULT;
995  out:
996 	free_page((unsigned long)tmp);
997 	return len;
998 }
999 
1000 static int proc_pid_readlink(struct dentry * dentry, char __user * buffer, int buflen)
1001 {
1002 	int error = -EACCES;
1003 	struct inode *inode = dentry->d_inode;
1004 	struct dentry *de;
1005 	struct vfsmount *mnt = NULL;
1006 
1007 	lock_kernel();
1008 
1009 	if (current->fsuid != inode->i_uid && !capable(CAP_DAC_OVERRIDE))
1010 		goto out;
1011 	error = proc_check_root(inode);
1012 	if (error)
1013 		goto out;
1014 
1015 	error = PROC_I(inode)->op.proc_get_link(inode, &de, &mnt);
1016 	if (error)
1017 		goto out;
1018 
1019 	error = do_proc_readlink(de, mnt, buffer, buflen);
1020 	dput(de);
1021 	mntput(mnt);
1022 out:
1023 	unlock_kernel();
1024 	return error;
1025 }
1026 
1027 static struct inode_operations proc_pid_link_inode_operations = {
1028 	.readlink	= proc_pid_readlink,
1029 	.follow_link	= proc_pid_follow_link
1030 };
1031 
1032 #define NUMBUF 10
1033 
1034 static int proc_readfd(struct file * filp, void * dirent, filldir_t filldir)
1035 {
1036 	struct inode *inode = filp->f_dentry->d_inode;
1037 	struct task_struct *p = proc_task(inode);
1038 	unsigned int fd, tid, ino;
1039 	int retval;
1040 	char buf[NUMBUF];
1041 	struct files_struct * files;
1042 
1043 	retval = -ENOENT;
1044 	if (!pid_alive(p))
1045 		goto out;
1046 	retval = 0;
1047 	tid = p->pid;
1048 
1049 	fd = filp->f_pos;
1050 	switch (fd) {
1051 		case 0:
1052 			if (filldir(dirent, ".", 1, 0, inode->i_ino, DT_DIR) < 0)
1053 				goto out;
1054 			filp->f_pos++;
1055 		case 1:
1056 			ino = fake_ino(tid, PROC_TID_INO);
1057 			if (filldir(dirent, "..", 2, 1, ino, DT_DIR) < 0)
1058 				goto out;
1059 			filp->f_pos++;
1060 		default:
1061 			files = get_files_struct(p);
1062 			if (!files)
1063 				goto out;
1064 			spin_lock(&files->file_lock);
1065 			for (fd = filp->f_pos-2;
1066 			     fd < files->max_fds;
1067 			     fd++, filp->f_pos++) {
1068 				unsigned int i,j;
1069 
1070 				if (!fcheck_files(files, fd))
1071 					continue;
1072 				spin_unlock(&files->file_lock);
1073 
1074 				j = NUMBUF;
1075 				i = fd;
1076 				do {
1077 					j--;
1078 					buf[j] = '0' + (i % 10);
1079 					i /= 10;
1080 				} while (i);
1081 
1082 				ino = fake_ino(tid, PROC_TID_FD_DIR + fd);
1083 				if (filldir(dirent, buf+j, NUMBUF-j, fd+2, ino, DT_LNK) < 0) {
1084 					spin_lock(&files->file_lock);
1085 					break;
1086 				}
1087 				spin_lock(&files->file_lock);
1088 			}
1089 			spin_unlock(&files->file_lock);
1090 			put_files_struct(files);
1091 	}
1092 out:
1093 	return retval;
1094 }
1095 
1096 static int proc_pident_readdir(struct file *filp,
1097 		void *dirent, filldir_t filldir,
1098 		struct pid_entry *ents, unsigned int nents)
1099 {
1100 	int i;
1101 	int pid;
1102 	struct dentry *dentry = filp->f_dentry;
1103 	struct inode *inode = dentry->d_inode;
1104 	struct pid_entry *p;
1105 	ino_t ino;
1106 	int ret;
1107 
1108 	ret = -ENOENT;
1109 	if (!pid_alive(proc_task(inode)))
1110 		goto out;
1111 
1112 	ret = 0;
1113 	pid = proc_task(inode)->pid;
1114 	i = filp->f_pos;
1115 	switch (i) {
1116 	case 0:
1117 		ino = inode->i_ino;
1118 		if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
1119 			goto out;
1120 		i++;
1121 		filp->f_pos++;
1122 		/* fall through */
1123 	case 1:
1124 		ino = parent_ino(dentry);
1125 		if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
1126 			goto out;
1127 		i++;
1128 		filp->f_pos++;
1129 		/* fall through */
1130 	default:
1131 		i -= 2;
1132 		if (i >= nents) {
1133 			ret = 1;
1134 			goto out;
1135 		}
1136 		p = ents + i;
1137 		while (p->name) {
1138 			if (filldir(dirent, p->name, p->len, filp->f_pos,
1139 				    fake_ino(pid, p->type), p->mode >> 12) < 0)
1140 				goto out;
1141 			filp->f_pos++;
1142 			p++;
1143 		}
1144 	}
1145 
1146 	ret = 1;
1147 out:
1148 	return ret;
1149 }
1150 
1151 static int proc_tgid_base_readdir(struct file * filp,
1152 			     void * dirent, filldir_t filldir)
1153 {
1154 	return proc_pident_readdir(filp,dirent,filldir,
1155 				   tgid_base_stuff,ARRAY_SIZE(tgid_base_stuff));
1156 }
1157 
1158 static int proc_tid_base_readdir(struct file * filp,
1159 			     void * dirent, filldir_t filldir)
1160 {
1161 	return proc_pident_readdir(filp,dirent,filldir,
1162 				   tid_base_stuff,ARRAY_SIZE(tid_base_stuff));
1163 }
1164 
1165 /* building an inode */
1166 
1167 static int task_dumpable(struct task_struct *task)
1168 {
1169 	int dumpable = 0;
1170 	struct mm_struct *mm;
1171 
1172 	task_lock(task);
1173 	mm = task->mm;
1174 	if (mm)
1175 		dumpable = mm->dumpable;
1176 	task_unlock(task);
1177 	if(dumpable == 1)
1178 		return 1;
1179 	return 0;
1180 }
1181 
1182 
1183 static struct inode *proc_pid_make_inode(struct super_block * sb, struct task_struct *task, int ino)
1184 {
1185 	struct inode * inode;
1186 	struct proc_inode *ei;
1187 
1188 	/* We need a new inode */
1189 
1190 	inode = new_inode(sb);
1191 	if (!inode)
1192 		goto out;
1193 
1194 	/* Common stuff */
1195 	ei = PROC_I(inode);
1196 	ei->task = NULL;
1197 	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
1198 	inode->i_ino = fake_ino(task->pid, ino);
1199 
1200 	if (!pid_alive(task))
1201 		goto out_unlock;
1202 
1203 	/*
1204 	 * grab the reference to task.
1205 	 */
1206 	get_task_struct(task);
1207 	ei->task = task;
1208 	ei->type = ino;
1209 	inode->i_uid = 0;
1210 	inode->i_gid = 0;
1211 	if (ino == PROC_TGID_INO || ino == PROC_TID_INO || task_dumpable(task)) {
1212 		inode->i_uid = task->euid;
1213 		inode->i_gid = task->egid;
1214 	}
1215 	security_task_to_inode(task, inode);
1216 
1217 out:
1218 	return inode;
1219 
1220 out_unlock:
1221 	ei->pde = NULL;
1222 	iput(inode);
1223 	return NULL;
1224 }
1225 
1226 /* dentry stuff */
1227 
1228 /*
1229  *	Exceptional case: normally we are not allowed to unhash a busy
1230  * directory. In this case, however, we can do it - no aliasing problems
1231  * due to the way we treat inodes.
1232  *
1233  * Rewrite the inode's ownerships here because the owning task may have
1234  * performed a setuid(), etc.
1235  */
1236 static int pid_revalidate(struct dentry *dentry, struct nameidata *nd)
1237 {
1238 	struct inode *inode = dentry->d_inode;
1239 	struct task_struct *task = proc_task(inode);
1240 	if (pid_alive(task)) {
1241 		if (proc_type(inode) == PROC_TGID_INO || proc_type(inode) == PROC_TID_INO || task_dumpable(task)) {
1242 			inode->i_uid = task->euid;
1243 			inode->i_gid = task->egid;
1244 		} else {
1245 			inode->i_uid = 0;
1246 			inode->i_gid = 0;
1247 		}
1248 		security_task_to_inode(task, inode);
1249 		return 1;
1250 	}
1251 	d_drop(dentry);
1252 	return 0;
1253 }
1254 
1255 static int tid_fd_revalidate(struct dentry *dentry, struct nameidata *nd)
1256 {
1257 	struct inode *inode = dentry->d_inode;
1258 	struct task_struct *task = proc_task(inode);
1259 	int fd = proc_type(inode) - PROC_TID_FD_DIR;
1260 	struct files_struct *files;
1261 
1262 	files = get_files_struct(task);
1263 	if (files) {
1264 		spin_lock(&files->file_lock);
1265 		if (fcheck_files(files, fd)) {
1266 			spin_unlock(&files->file_lock);
1267 			put_files_struct(files);
1268 			if (task_dumpable(task)) {
1269 				inode->i_uid = task->euid;
1270 				inode->i_gid = task->egid;
1271 			} else {
1272 				inode->i_uid = 0;
1273 				inode->i_gid = 0;
1274 			}
1275 			security_task_to_inode(task, inode);
1276 			return 1;
1277 		}
1278 		spin_unlock(&files->file_lock);
1279 		put_files_struct(files);
1280 	}
1281 	d_drop(dentry);
1282 	return 0;
1283 }
1284 
1285 static void pid_base_iput(struct dentry *dentry, struct inode *inode)
1286 {
1287 	struct task_struct *task = proc_task(inode);
1288 	spin_lock(&task->proc_lock);
1289 	if (task->proc_dentry == dentry)
1290 		task->proc_dentry = NULL;
1291 	spin_unlock(&task->proc_lock);
1292 	iput(inode);
1293 }
1294 
1295 static int pid_delete_dentry(struct dentry * dentry)
1296 {
1297 	/* Is the task we represent dead?
1298 	 * If so, then don't put the dentry on the lru list,
1299 	 * kill it immediately.
1300 	 */
1301 	return !pid_alive(proc_task(dentry->d_inode));
1302 }
1303 
1304 static struct dentry_operations tid_fd_dentry_operations =
1305 {
1306 	.d_revalidate	= tid_fd_revalidate,
1307 	.d_delete	= pid_delete_dentry,
1308 };
1309 
1310 static struct dentry_operations pid_dentry_operations =
1311 {
1312 	.d_revalidate	= pid_revalidate,
1313 	.d_delete	= pid_delete_dentry,
1314 };
1315 
1316 static struct dentry_operations pid_base_dentry_operations =
1317 {
1318 	.d_revalidate	= pid_revalidate,
1319 	.d_iput		= pid_base_iput,
1320 	.d_delete	= pid_delete_dentry,
1321 };
1322 
1323 /* Lookups */
1324 
1325 static unsigned name_to_int(struct dentry *dentry)
1326 {
1327 	const char *name = dentry->d_name.name;
1328 	int len = dentry->d_name.len;
1329 	unsigned n = 0;
1330 
1331 	if (len > 1 && *name == '0')
1332 		goto out;
1333 	while (len-- > 0) {
1334 		unsigned c = *name++ - '0';
1335 		if (c > 9)
1336 			goto out;
1337 		if (n >= (~0U-9)/10)
1338 			goto out;
1339 		n *= 10;
1340 		n += c;
1341 	}
1342 	return n;
1343 out:
1344 	return ~0U;
1345 }
1346 
1347 /* SMP-safe */
1348 static struct dentry *proc_lookupfd(struct inode * dir, struct dentry * dentry, struct nameidata *nd)
1349 {
1350 	struct task_struct *task = proc_task(dir);
1351 	unsigned fd = name_to_int(dentry);
1352 	struct file * file;
1353 	struct files_struct * files;
1354 	struct inode *inode;
1355 	struct proc_inode *ei;
1356 
1357 	if (fd == ~0U)
1358 		goto out;
1359 	if (!pid_alive(task))
1360 		goto out;
1361 
1362 	inode = proc_pid_make_inode(dir->i_sb, task, PROC_TID_FD_DIR+fd);
1363 	if (!inode)
1364 		goto out;
1365 	ei = PROC_I(inode);
1366 	files = get_files_struct(task);
1367 	if (!files)
1368 		goto out_unlock;
1369 	inode->i_mode = S_IFLNK;
1370 	spin_lock(&files->file_lock);
1371 	file = fcheck_files(files, fd);
1372 	if (!file)
1373 		goto out_unlock2;
1374 	if (file->f_mode & 1)
1375 		inode->i_mode |= S_IRUSR | S_IXUSR;
1376 	if (file->f_mode & 2)
1377 		inode->i_mode |= S_IWUSR | S_IXUSR;
1378 	spin_unlock(&files->file_lock);
1379 	put_files_struct(files);
1380 	inode->i_op = &proc_pid_link_inode_operations;
1381 	inode->i_size = 64;
1382 	ei->op.proc_get_link = proc_fd_link;
1383 	dentry->d_op = &tid_fd_dentry_operations;
1384 	d_add(dentry, inode);
1385 	return NULL;
1386 
1387 out_unlock2:
1388 	spin_unlock(&files->file_lock);
1389 	put_files_struct(files);
1390 out_unlock:
1391 	iput(inode);
1392 out:
1393 	return ERR_PTR(-ENOENT);
1394 }
1395 
1396 static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldir);
1397 static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd);
1398 
1399 static struct file_operations proc_fd_operations = {
1400 	.read		= generic_read_dir,
1401 	.readdir	= proc_readfd,
1402 };
1403 
1404 static struct file_operations proc_task_operations = {
1405 	.read		= generic_read_dir,
1406 	.readdir	= proc_task_readdir,
1407 };
1408 
1409 /*
1410  * proc directories can do almost nothing..
1411  */
1412 static struct inode_operations proc_fd_inode_operations = {
1413 	.lookup		= proc_lookupfd,
1414 	.permission	= proc_permission,
1415 };
1416 
1417 static struct inode_operations proc_task_inode_operations = {
1418 	.lookup		= proc_task_lookup,
1419 	.permission	= proc_permission,
1420 };
1421 
1422 #ifdef CONFIG_SECURITY
1423 static ssize_t proc_pid_attr_read(struct file * file, char __user * buf,
1424 				  size_t count, loff_t *ppos)
1425 {
1426 	struct inode * inode = file->f_dentry->d_inode;
1427 	unsigned long page;
1428 	ssize_t length;
1429 	struct task_struct *task = proc_task(inode);
1430 
1431 	if (count > PAGE_SIZE)
1432 		count = PAGE_SIZE;
1433 	if (!(page = __get_free_page(GFP_KERNEL)))
1434 		return -ENOMEM;
1435 
1436 	length = security_getprocattr(task,
1437 				      (char*)file->f_dentry->d_name.name,
1438 				      (void*)page, count);
1439 	if (length >= 0)
1440 		length = simple_read_from_buffer(buf, count, ppos, (char *)page, length);
1441 	free_page(page);
1442 	return length;
1443 }
1444 
1445 static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
1446 				   size_t count, loff_t *ppos)
1447 {
1448 	struct inode * inode = file->f_dentry->d_inode;
1449 	char *page;
1450 	ssize_t length;
1451 	struct task_struct *task = proc_task(inode);
1452 
1453 	if (count > PAGE_SIZE)
1454 		count = PAGE_SIZE;
1455 	if (*ppos != 0) {
1456 		/* No partial writes. */
1457 		return -EINVAL;
1458 	}
1459 	page = (char*)__get_free_page(GFP_USER);
1460 	if (!page)
1461 		return -ENOMEM;
1462 	length = -EFAULT;
1463 	if (copy_from_user(page, buf, count))
1464 		goto out;
1465 
1466 	length = security_setprocattr(task,
1467 				      (char*)file->f_dentry->d_name.name,
1468 				      (void*)page, count);
1469 out:
1470 	free_page((unsigned long) page);
1471 	return length;
1472 }
1473 
1474 static struct file_operations proc_pid_attr_operations = {
1475 	.read		= proc_pid_attr_read,
1476 	.write		= proc_pid_attr_write,
1477 };
1478 
1479 static struct file_operations proc_tid_attr_operations;
1480 static struct inode_operations proc_tid_attr_inode_operations;
1481 static struct file_operations proc_tgid_attr_operations;
1482 static struct inode_operations proc_tgid_attr_inode_operations;
1483 #endif
1484 
1485 static int get_tid_list(int index, unsigned int *tids, struct inode *dir);
1486 
1487 /* SMP-safe */
1488 static struct dentry *proc_pident_lookup(struct inode *dir,
1489 					 struct dentry *dentry,
1490 					 struct pid_entry *ents)
1491 {
1492 	struct inode *inode;
1493 	int error;
1494 	struct task_struct *task = proc_task(dir);
1495 	struct pid_entry *p;
1496 	struct proc_inode *ei;
1497 
1498 	error = -ENOENT;
1499 	inode = NULL;
1500 
1501 	if (!pid_alive(task))
1502 		goto out;
1503 
1504 	for (p = ents; p->name; p++) {
1505 		if (p->len != dentry->d_name.len)
1506 			continue;
1507 		if (!memcmp(dentry->d_name.name, p->name, p->len))
1508 			break;
1509 	}
1510 	if (!p->name)
1511 		goto out;
1512 
1513 	error = -EINVAL;
1514 	inode = proc_pid_make_inode(dir->i_sb, task, p->type);
1515 	if (!inode)
1516 		goto out;
1517 
1518 	ei = PROC_I(inode);
1519 	inode->i_mode = p->mode;
1520 	/*
1521 	 * Yes, it does not scale. And it should not. Don't add
1522 	 * new entries into /proc/<tgid>/ without very good reasons.
1523 	 */
1524 	switch(p->type) {
1525 		case PROC_TGID_TASK:
1526 			inode->i_nlink = 2 + get_tid_list(2, NULL, dir);
1527 			inode->i_op = &proc_task_inode_operations;
1528 			inode->i_fop = &proc_task_operations;
1529 			break;
1530 		case PROC_TID_FD:
1531 		case PROC_TGID_FD:
1532 			inode->i_nlink = 2;
1533 			inode->i_op = &proc_fd_inode_operations;
1534 			inode->i_fop = &proc_fd_operations;
1535 			break;
1536 		case PROC_TID_EXE:
1537 		case PROC_TGID_EXE:
1538 			inode->i_op = &proc_pid_link_inode_operations;
1539 			ei->op.proc_get_link = proc_exe_link;
1540 			break;
1541 		case PROC_TID_CWD:
1542 		case PROC_TGID_CWD:
1543 			inode->i_op = &proc_pid_link_inode_operations;
1544 			ei->op.proc_get_link = proc_cwd_link;
1545 			break;
1546 		case PROC_TID_ROOT:
1547 		case PROC_TGID_ROOT:
1548 			inode->i_op = &proc_pid_link_inode_operations;
1549 			ei->op.proc_get_link = proc_root_link;
1550 			break;
1551 		case PROC_TID_ENVIRON:
1552 		case PROC_TGID_ENVIRON:
1553 			inode->i_fop = &proc_info_file_operations;
1554 			ei->op.proc_read = proc_pid_environ;
1555 			break;
1556 		case PROC_TID_AUXV:
1557 		case PROC_TGID_AUXV:
1558 			inode->i_fop = &proc_info_file_operations;
1559 			ei->op.proc_read = proc_pid_auxv;
1560 			break;
1561 		case PROC_TID_STATUS:
1562 		case PROC_TGID_STATUS:
1563 			inode->i_fop = &proc_info_file_operations;
1564 			ei->op.proc_read = proc_pid_status;
1565 			break;
1566 		case PROC_TID_STAT:
1567 			inode->i_fop = &proc_info_file_operations;
1568 			ei->op.proc_read = proc_tid_stat;
1569 			break;
1570 		case PROC_TGID_STAT:
1571 			inode->i_fop = &proc_info_file_operations;
1572 			ei->op.proc_read = proc_tgid_stat;
1573 			break;
1574 		case PROC_TID_CMDLINE:
1575 		case PROC_TGID_CMDLINE:
1576 			inode->i_fop = &proc_info_file_operations;
1577 			ei->op.proc_read = proc_pid_cmdline;
1578 			break;
1579 		case PROC_TID_STATM:
1580 		case PROC_TGID_STATM:
1581 			inode->i_fop = &proc_info_file_operations;
1582 			ei->op.proc_read = proc_pid_statm;
1583 			break;
1584 		case PROC_TID_MAPS:
1585 		case PROC_TGID_MAPS:
1586 			inode->i_fop = &proc_maps_operations;
1587 			break;
1588 #ifdef CONFIG_NUMA
1589 		case PROC_TID_NUMA_MAPS:
1590 		case PROC_TGID_NUMA_MAPS:
1591 			inode->i_fop = &proc_numa_maps_operations;
1592 			break;
1593 #endif
1594 		case PROC_TID_MEM:
1595 		case PROC_TGID_MEM:
1596 			inode->i_op = &proc_mem_inode_operations;
1597 			inode->i_fop = &proc_mem_operations;
1598 			break;
1599 #ifdef CONFIG_SECCOMP
1600 		case PROC_TID_SECCOMP:
1601 		case PROC_TGID_SECCOMP:
1602 			inode->i_fop = &proc_seccomp_operations;
1603 			break;
1604 #endif /* CONFIG_SECCOMP */
1605 		case PROC_TID_MOUNTS:
1606 		case PROC_TGID_MOUNTS:
1607 			inode->i_fop = &proc_mounts_operations;
1608 			break;
1609 		case PROC_TID_SMAPS:
1610 		case PROC_TGID_SMAPS:
1611 			inode->i_fop = &proc_smaps_operations;
1612 			break;
1613 #ifdef CONFIG_SECURITY
1614 		case PROC_TID_ATTR:
1615 			inode->i_nlink = 2;
1616 			inode->i_op = &proc_tid_attr_inode_operations;
1617 			inode->i_fop = &proc_tid_attr_operations;
1618 			break;
1619 		case PROC_TGID_ATTR:
1620 			inode->i_nlink = 2;
1621 			inode->i_op = &proc_tgid_attr_inode_operations;
1622 			inode->i_fop = &proc_tgid_attr_operations;
1623 			break;
1624 		case PROC_TID_ATTR_CURRENT:
1625 		case PROC_TGID_ATTR_CURRENT:
1626 		case PROC_TID_ATTR_PREV:
1627 		case PROC_TGID_ATTR_PREV:
1628 		case PROC_TID_ATTR_EXEC:
1629 		case PROC_TGID_ATTR_EXEC:
1630 		case PROC_TID_ATTR_FSCREATE:
1631 		case PROC_TGID_ATTR_FSCREATE:
1632 			inode->i_fop = &proc_pid_attr_operations;
1633 			break;
1634 #endif
1635 #ifdef CONFIG_KALLSYMS
1636 		case PROC_TID_WCHAN:
1637 		case PROC_TGID_WCHAN:
1638 			inode->i_fop = &proc_info_file_operations;
1639 			ei->op.proc_read = proc_pid_wchan;
1640 			break;
1641 #endif
1642 #ifdef CONFIG_SCHEDSTATS
1643 		case PROC_TID_SCHEDSTAT:
1644 		case PROC_TGID_SCHEDSTAT:
1645 			inode->i_fop = &proc_info_file_operations;
1646 			ei->op.proc_read = proc_pid_schedstat;
1647 			break;
1648 #endif
1649 #ifdef CONFIG_CPUSETS
1650 		case PROC_TID_CPUSET:
1651 		case PROC_TGID_CPUSET:
1652 			inode->i_fop = &proc_cpuset_operations;
1653 			break;
1654 #endif
1655 		case PROC_TID_OOM_SCORE:
1656 		case PROC_TGID_OOM_SCORE:
1657 			inode->i_fop = &proc_info_file_operations;
1658 			ei->op.proc_read = proc_oom_score;
1659 			break;
1660 		case PROC_TID_OOM_ADJUST:
1661 		case PROC_TGID_OOM_ADJUST:
1662 			inode->i_fop = &proc_oom_adjust_operations;
1663 			break;
1664 #ifdef CONFIG_AUDITSYSCALL
1665 		case PROC_TID_LOGINUID:
1666 		case PROC_TGID_LOGINUID:
1667 			inode->i_fop = &proc_loginuid_operations;
1668 			break;
1669 #endif
1670 		default:
1671 			printk("procfs: impossible type (%d)",p->type);
1672 			iput(inode);
1673 			return ERR_PTR(-EINVAL);
1674 	}
1675 	dentry->d_op = &pid_dentry_operations;
1676 	d_add(dentry, inode);
1677 	return NULL;
1678 
1679 out:
1680 	return ERR_PTR(error);
1681 }
1682 
1683 static struct dentry *proc_tgid_base_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd){
1684 	return proc_pident_lookup(dir, dentry, tgid_base_stuff);
1685 }
1686 
1687 static struct dentry *proc_tid_base_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd){
1688 	return proc_pident_lookup(dir, dentry, tid_base_stuff);
1689 }
1690 
1691 static struct file_operations proc_tgid_base_operations = {
1692 	.read		= generic_read_dir,
1693 	.readdir	= proc_tgid_base_readdir,
1694 };
1695 
1696 static struct file_operations proc_tid_base_operations = {
1697 	.read		= generic_read_dir,
1698 	.readdir	= proc_tid_base_readdir,
1699 };
1700 
1701 static struct inode_operations proc_tgid_base_inode_operations = {
1702 	.lookup		= proc_tgid_base_lookup,
1703 };
1704 
1705 static struct inode_operations proc_tid_base_inode_operations = {
1706 	.lookup		= proc_tid_base_lookup,
1707 };
1708 
1709 #ifdef CONFIG_SECURITY
1710 static int proc_tgid_attr_readdir(struct file * filp,
1711 			     void * dirent, filldir_t filldir)
1712 {
1713 	return proc_pident_readdir(filp,dirent,filldir,
1714 				   tgid_attr_stuff,ARRAY_SIZE(tgid_attr_stuff));
1715 }
1716 
1717 static int proc_tid_attr_readdir(struct file * filp,
1718 			     void * dirent, filldir_t filldir)
1719 {
1720 	return proc_pident_readdir(filp,dirent,filldir,
1721 				   tid_attr_stuff,ARRAY_SIZE(tid_attr_stuff));
1722 }
1723 
1724 static struct file_operations proc_tgid_attr_operations = {
1725 	.read		= generic_read_dir,
1726 	.readdir	= proc_tgid_attr_readdir,
1727 };
1728 
1729 static struct file_operations proc_tid_attr_operations = {
1730 	.read		= generic_read_dir,
1731 	.readdir	= proc_tid_attr_readdir,
1732 };
1733 
1734 static struct dentry *proc_tgid_attr_lookup(struct inode *dir,
1735 				struct dentry *dentry, struct nameidata *nd)
1736 {
1737 	return proc_pident_lookup(dir, dentry, tgid_attr_stuff);
1738 }
1739 
1740 static struct dentry *proc_tid_attr_lookup(struct inode *dir,
1741 				struct dentry *dentry, struct nameidata *nd)
1742 {
1743 	return proc_pident_lookup(dir, dentry, tid_attr_stuff);
1744 }
1745 
1746 static struct inode_operations proc_tgid_attr_inode_operations = {
1747 	.lookup		= proc_tgid_attr_lookup,
1748 };
1749 
1750 static struct inode_operations proc_tid_attr_inode_operations = {
1751 	.lookup		= proc_tid_attr_lookup,
1752 };
1753 #endif
1754 
1755 /*
1756  * /proc/self:
1757  */
1758 static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
1759 			      int buflen)
1760 {
1761 	char tmp[30];
1762 	sprintf(tmp, "%d", current->tgid);
1763 	return vfs_readlink(dentry,buffer,buflen,tmp);
1764 }
1765 
1766 static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)
1767 {
1768 	char tmp[30];
1769 	sprintf(tmp, "%d", current->tgid);
1770 	return ERR_PTR(vfs_follow_link(nd,tmp));
1771 }
1772 
1773 static struct inode_operations proc_self_inode_operations = {
1774 	.readlink	= proc_self_readlink,
1775 	.follow_link	= proc_self_follow_link,
1776 };
1777 
1778 /**
1779  * proc_pid_unhash -  Unhash /proc/@pid entry from the dcache.
1780  * @p: task that should be flushed.
1781  *
1782  * Drops the /proc/@pid dcache entry from the hash chains.
1783  *
1784  * Dropping /proc/@pid entries and detach_pid must be synchroneous,
1785  * otherwise e.g. /proc/@pid/exe might point to the wrong executable,
1786  * if the pid value is immediately reused. This is enforced by
1787  * - caller must acquire spin_lock(p->proc_lock)
1788  * - must be called before detach_pid()
1789  * - proc_pid_lookup acquires proc_lock, and checks that
1790  *   the target is not dead by looking at the attach count
1791  *   of PIDTYPE_PID.
1792  */
1793 
1794 struct dentry *proc_pid_unhash(struct task_struct *p)
1795 {
1796 	struct dentry *proc_dentry;
1797 
1798 	proc_dentry = p->proc_dentry;
1799 	if (proc_dentry != NULL) {
1800 
1801 		spin_lock(&dcache_lock);
1802 		spin_lock(&proc_dentry->d_lock);
1803 		if (!d_unhashed(proc_dentry)) {
1804 			dget_locked(proc_dentry);
1805 			__d_drop(proc_dentry);
1806 			spin_unlock(&proc_dentry->d_lock);
1807 		} else {
1808 			spin_unlock(&proc_dentry->d_lock);
1809 			proc_dentry = NULL;
1810 		}
1811 		spin_unlock(&dcache_lock);
1812 	}
1813 	return proc_dentry;
1814 }
1815 
1816 /**
1817  * proc_pid_flush - recover memory used by stale /proc/@pid/x entries
1818  * @proc_dentry: directoy to prune.
1819  *
1820  * Shrink the /proc directory that was used by the just killed thread.
1821  */
1822 
1823 void proc_pid_flush(struct dentry *proc_dentry)
1824 {
1825 	might_sleep();
1826 	if(proc_dentry != NULL) {
1827 		shrink_dcache_parent(proc_dentry);
1828 		dput(proc_dentry);
1829 	}
1830 }
1831 
1832 /* SMP-safe */
1833 struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd)
1834 {
1835 	struct task_struct *task;
1836 	struct inode *inode;
1837 	struct proc_inode *ei;
1838 	unsigned tgid;
1839 	int died;
1840 
1841 	if (dentry->d_name.len == 4 && !memcmp(dentry->d_name.name,"self",4)) {
1842 		inode = new_inode(dir->i_sb);
1843 		if (!inode)
1844 			return ERR_PTR(-ENOMEM);
1845 		ei = PROC_I(inode);
1846 		inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
1847 		inode->i_ino = fake_ino(0, PROC_TGID_INO);
1848 		ei->pde = NULL;
1849 		inode->i_mode = S_IFLNK|S_IRWXUGO;
1850 		inode->i_uid = inode->i_gid = 0;
1851 		inode->i_size = 64;
1852 		inode->i_op = &proc_self_inode_operations;
1853 		d_add(dentry, inode);
1854 		return NULL;
1855 	}
1856 	tgid = name_to_int(dentry);
1857 	if (tgid == ~0U)
1858 		goto out;
1859 
1860 	read_lock(&tasklist_lock);
1861 	task = find_task_by_pid(tgid);
1862 	if (task)
1863 		get_task_struct(task);
1864 	read_unlock(&tasklist_lock);
1865 	if (!task)
1866 		goto out;
1867 
1868 	inode = proc_pid_make_inode(dir->i_sb, task, PROC_TGID_INO);
1869 
1870 
1871 	if (!inode) {
1872 		put_task_struct(task);
1873 		goto out;
1874 	}
1875 	inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
1876 	inode->i_op = &proc_tgid_base_inode_operations;
1877 	inode->i_fop = &proc_tgid_base_operations;
1878 	inode->i_flags|=S_IMMUTABLE;
1879 #ifdef CONFIG_SECURITY
1880 	inode->i_nlink = 5;
1881 #else
1882 	inode->i_nlink = 4;
1883 #endif
1884 
1885 	dentry->d_op = &pid_base_dentry_operations;
1886 
1887 	died = 0;
1888 	d_add(dentry, inode);
1889 	spin_lock(&task->proc_lock);
1890 	task->proc_dentry = dentry;
1891 	if (!pid_alive(task)) {
1892 		dentry = proc_pid_unhash(task);
1893 		died = 1;
1894 	}
1895 	spin_unlock(&task->proc_lock);
1896 
1897 	put_task_struct(task);
1898 	if (died) {
1899 		proc_pid_flush(dentry);
1900 		goto out;
1901 	}
1902 	return NULL;
1903 out:
1904 	return ERR_PTR(-ENOENT);
1905 }
1906 
1907 /* SMP-safe */
1908 static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd)
1909 {
1910 	struct task_struct *task;
1911 	struct task_struct *leader = proc_task(dir);
1912 	struct inode *inode;
1913 	unsigned tid;
1914 
1915 	tid = name_to_int(dentry);
1916 	if (tid == ~0U)
1917 		goto out;
1918 
1919 	read_lock(&tasklist_lock);
1920 	task = find_task_by_pid(tid);
1921 	if (task)
1922 		get_task_struct(task);
1923 	read_unlock(&tasklist_lock);
1924 	if (!task)
1925 		goto out;
1926 	if (leader->tgid != task->tgid)
1927 		goto out_drop_task;
1928 
1929 	inode = proc_pid_make_inode(dir->i_sb, task, PROC_TID_INO);
1930 
1931 
1932 	if (!inode)
1933 		goto out_drop_task;
1934 	inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
1935 	inode->i_op = &proc_tid_base_inode_operations;
1936 	inode->i_fop = &proc_tid_base_operations;
1937 	inode->i_flags|=S_IMMUTABLE;
1938 #ifdef CONFIG_SECURITY
1939 	inode->i_nlink = 4;
1940 #else
1941 	inode->i_nlink = 3;
1942 #endif
1943 
1944 	dentry->d_op = &pid_base_dentry_operations;
1945 
1946 	d_add(dentry, inode);
1947 
1948 	put_task_struct(task);
1949 	return NULL;
1950 out_drop_task:
1951 	put_task_struct(task);
1952 out:
1953 	return ERR_PTR(-ENOENT);
1954 }
1955 
1956 #define PROC_NUMBUF 10
1957 #define PROC_MAXPIDS 20
1958 
1959 /*
1960  * Get a few tgid's to return for filldir - we need to hold the
1961  * tasklist lock while doing this, and we must release it before
1962  * we actually do the filldir itself, so we use a temp buffer..
1963  */
1964 static int get_tgid_list(int index, unsigned long version, unsigned int *tgids)
1965 {
1966 	struct task_struct *p;
1967 	int nr_tgids = 0;
1968 
1969 	index--;
1970 	read_lock(&tasklist_lock);
1971 	p = NULL;
1972 	if (version) {
1973 		p = find_task_by_pid(version);
1974 		if (p && !thread_group_leader(p))
1975 			p = NULL;
1976 	}
1977 
1978 	if (p)
1979 		index = 0;
1980 	else
1981 		p = next_task(&init_task);
1982 
1983 	for ( ; p != &init_task; p = next_task(p)) {
1984 		int tgid = p->pid;
1985 		if (!pid_alive(p))
1986 			continue;
1987 		if (--index >= 0)
1988 			continue;
1989 		tgids[nr_tgids] = tgid;
1990 		nr_tgids++;
1991 		if (nr_tgids >= PROC_MAXPIDS)
1992 			break;
1993 	}
1994 	read_unlock(&tasklist_lock);
1995 	return nr_tgids;
1996 }
1997 
1998 /*
1999  * Get a few tid's to return for filldir - we need to hold the
2000  * tasklist lock while doing this, and we must release it before
2001  * we actually do the filldir itself, so we use a temp buffer..
2002  */
2003 static int get_tid_list(int index, unsigned int *tids, struct inode *dir)
2004 {
2005 	struct task_struct *leader_task = proc_task(dir);
2006 	struct task_struct *task = leader_task;
2007 	int nr_tids = 0;
2008 
2009 	index -= 2;
2010 	read_lock(&tasklist_lock);
2011 	/*
2012 	 * The starting point task (leader_task) might be an already
2013 	 * unlinked task, which cannot be used to access the task-list
2014 	 * via next_thread().
2015 	 */
2016 	if (pid_alive(task)) do {
2017 		int tid = task->pid;
2018 
2019 		if (--index >= 0)
2020 			continue;
2021 		if (tids != NULL)
2022 			tids[nr_tids] = tid;
2023 		nr_tids++;
2024 		if (nr_tids >= PROC_MAXPIDS)
2025 			break;
2026 	} while ((task = next_thread(task)) != leader_task);
2027 	read_unlock(&tasklist_lock);
2028 	return nr_tids;
2029 }
2030 
2031 /* for the /proc/ directory itself, after non-process stuff has been done */
2032 int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
2033 {
2034 	unsigned int tgid_array[PROC_MAXPIDS];
2035 	char buf[PROC_NUMBUF];
2036 	unsigned int nr = filp->f_pos - FIRST_PROCESS_ENTRY;
2037 	unsigned int nr_tgids, i;
2038 	int next_tgid;
2039 
2040 	if (!nr) {
2041 		ino_t ino = fake_ino(0,PROC_TGID_INO);
2042 		if (filldir(dirent, "self", 4, filp->f_pos, ino, DT_LNK) < 0)
2043 			return 0;
2044 		filp->f_pos++;
2045 		nr++;
2046 	}
2047 
2048 	/* f_version caches the tgid value that the last readdir call couldn't
2049 	 * return. lseek aka telldir automagically resets f_version to 0.
2050 	 */
2051 	next_tgid = filp->f_version;
2052 	filp->f_version = 0;
2053 	for (;;) {
2054 		nr_tgids = get_tgid_list(nr, next_tgid, tgid_array);
2055 		if (!nr_tgids) {
2056 			/* no more entries ! */
2057 			break;
2058 		}
2059 		next_tgid = 0;
2060 
2061 		/* do not use the last found pid, reserve it for next_tgid */
2062 		if (nr_tgids == PROC_MAXPIDS) {
2063 			nr_tgids--;
2064 			next_tgid = tgid_array[nr_tgids];
2065 		}
2066 
2067 		for (i=0;i<nr_tgids;i++) {
2068 			int tgid = tgid_array[i];
2069 			ino_t ino = fake_ino(tgid,PROC_TGID_INO);
2070 			unsigned long j = PROC_NUMBUF;
2071 
2072 			do
2073 				buf[--j] = '0' + (tgid % 10);
2074 			while ((tgid /= 10) != 0);
2075 
2076 			if (filldir(dirent, buf+j, PROC_NUMBUF-j, filp->f_pos, ino, DT_DIR) < 0) {
2077 				/* returning this tgid failed, save it as the first
2078 				 * pid for the next readir call */
2079 				filp->f_version = tgid_array[i];
2080 				goto out;
2081 			}
2082 			filp->f_pos++;
2083 			nr++;
2084 		}
2085 	}
2086 out:
2087 	return 0;
2088 }
2089 
2090 /* for the /proc/TGID/task/ directories */
2091 static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldir)
2092 {
2093 	unsigned int tid_array[PROC_MAXPIDS];
2094 	char buf[PROC_NUMBUF];
2095 	unsigned int nr_tids, i;
2096 	struct dentry *dentry = filp->f_dentry;
2097 	struct inode *inode = dentry->d_inode;
2098 	int retval = -ENOENT;
2099 	ino_t ino;
2100 	unsigned long pos = filp->f_pos;  /* avoiding "long long" filp->f_pos */
2101 
2102 	if (!pid_alive(proc_task(inode)))
2103 		goto out;
2104 	retval = 0;
2105 
2106 	switch (pos) {
2107 	case 0:
2108 		ino = inode->i_ino;
2109 		if (filldir(dirent, ".", 1, pos, ino, DT_DIR) < 0)
2110 			goto out;
2111 		pos++;
2112 		/* fall through */
2113 	case 1:
2114 		ino = parent_ino(dentry);
2115 		if (filldir(dirent, "..", 2, pos, ino, DT_DIR) < 0)
2116 			goto out;
2117 		pos++;
2118 		/* fall through */
2119 	}
2120 
2121 	nr_tids = get_tid_list(pos, tid_array, inode);
2122 	inode->i_nlink = pos + nr_tids;
2123 
2124 	for (i = 0; i < nr_tids; i++) {
2125 		unsigned long j = PROC_NUMBUF;
2126 		int tid = tid_array[i];
2127 
2128 		ino = fake_ino(tid,PROC_TID_INO);
2129 
2130 		do
2131 			buf[--j] = '0' + (tid % 10);
2132 		while ((tid /= 10) != 0);
2133 
2134 		if (filldir(dirent, buf+j, PROC_NUMBUF-j, pos, ino, DT_DIR) < 0)
2135 			break;
2136 		pos++;
2137 	}
2138 out:
2139 	filp->f_pos = pos;
2140 	return retval;
2141 }
2142