xref: /linux/fs/proc/base.c (revision d67b569f5f620c0fb95d5212642746b7ba9d29e4)
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 #include <asm/uaccess.h>
17 
18 #include <linux/config.h>
19 #include <linux/errno.h>
20 #include <linux/time.h>
21 #include <linux/proc_fs.h>
22 #include <linux/stat.h>
23 #include <linux/init.h>
24 #include <linux/file.h>
25 #include <linux/string.h>
26 #include <linux/seq_file.h>
27 #include <linux/namei.h>
28 #include <linux/namespace.h>
29 #include <linux/mm.h>
30 #include <linux/smp_lock.h>
31 #include <linux/kallsyms.h>
32 #include <linux/mount.h>
33 #include <linux/security.h>
34 #include <linux/ptrace.h>
35 #include <linux/seccomp.h>
36 #include <linux/cpuset.h>
37 #include <linux/audit.h>
38 #include "internal.h"
39 
40 /*
41  * For hysterical raisins we keep the same inumbers as in the old procfs.
42  * Feel free to change the macro below - just keep the range distinct from
43  * inumbers of the rest of procfs (currently those are in 0x0000--0xffff).
44  * As soon as we'll get a separate superblock we will be able to forget
45  * about magical ranges too.
46  */
47 
48 #define fake_ino(pid,ino) (((pid)<<16)|(ino))
49 
50 enum pid_directory_inos {
51 	PROC_TGID_INO = 2,
52 	PROC_TGID_TASK,
53 	PROC_TGID_STATUS,
54 	PROC_TGID_MEM,
55 #ifdef CONFIG_SECCOMP
56 	PROC_TGID_SECCOMP,
57 #endif
58 	PROC_TGID_CWD,
59 	PROC_TGID_ROOT,
60 	PROC_TGID_EXE,
61 	PROC_TGID_FD,
62 	PROC_TGID_ENVIRON,
63 	PROC_TGID_AUXV,
64 	PROC_TGID_CMDLINE,
65 	PROC_TGID_STAT,
66 	PROC_TGID_STATM,
67 	PROC_TGID_MAPS,
68 	PROC_TGID_MOUNTS,
69 	PROC_TGID_WCHAN,
70 #ifdef CONFIG_SCHEDSTATS
71 	PROC_TGID_SCHEDSTAT,
72 #endif
73 #ifdef CONFIG_CPUSETS
74 	PROC_TGID_CPUSET,
75 #endif
76 #ifdef CONFIG_SECURITY
77 	PROC_TGID_ATTR,
78 	PROC_TGID_ATTR_CURRENT,
79 	PROC_TGID_ATTR_PREV,
80 	PROC_TGID_ATTR_EXEC,
81 	PROC_TGID_ATTR_FSCREATE,
82 #endif
83 #ifdef CONFIG_AUDITSYSCALL
84 	PROC_TGID_LOGINUID,
85 #endif
86 	PROC_TGID_FD_DIR,
87 	PROC_TGID_OOM_SCORE,
88 	PROC_TGID_OOM_ADJUST,
89 	PROC_TID_INO,
90 	PROC_TID_STATUS,
91 	PROC_TID_MEM,
92 #ifdef CONFIG_SECCOMP
93 	PROC_TID_SECCOMP,
94 #endif
95 	PROC_TID_CWD,
96 	PROC_TID_ROOT,
97 	PROC_TID_EXE,
98 	PROC_TID_FD,
99 	PROC_TID_ENVIRON,
100 	PROC_TID_AUXV,
101 	PROC_TID_CMDLINE,
102 	PROC_TID_STAT,
103 	PROC_TID_STATM,
104 	PROC_TID_MAPS,
105 	PROC_TID_MOUNTS,
106 	PROC_TID_WCHAN,
107 #ifdef CONFIG_SCHEDSTATS
108 	PROC_TID_SCHEDSTAT,
109 #endif
110 #ifdef CONFIG_CPUSETS
111 	PROC_TID_CPUSET,
112 #endif
113 #ifdef CONFIG_SECURITY
114 	PROC_TID_ATTR,
115 	PROC_TID_ATTR_CURRENT,
116 	PROC_TID_ATTR_PREV,
117 	PROC_TID_ATTR_EXEC,
118 	PROC_TID_ATTR_FSCREATE,
119 #endif
120 #ifdef CONFIG_AUDITSYSCALL
121 	PROC_TID_LOGINUID,
122 #endif
123 	PROC_TID_FD_DIR = 0x8000,	/* 0x8000-0xffff */
124 	PROC_TID_OOM_SCORE,
125 	PROC_TID_OOM_ADJUST,
126 };
127 
128 struct pid_entry {
129 	int type;
130 	int len;
131 	char *name;
132 	mode_t mode;
133 };
134 
135 #define E(type,name,mode) {(type),sizeof(name)-1,(name),(mode)}
136 
137 static struct pid_entry tgid_base_stuff[] = {
138 	E(PROC_TGID_TASK,      "task",    S_IFDIR|S_IRUGO|S_IXUGO),
139 	E(PROC_TGID_FD,        "fd",      S_IFDIR|S_IRUSR|S_IXUSR),
140 	E(PROC_TGID_ENVIRON,   "environ", S_IFREG|S_IRUSR),
141 	E(PROC_TGID_AUXV,      "auxv",	  S_IFREG|S_IRUSR),
142 	E(PROC_TGID_STATUS,    "status",  S_IFREG|S_IRUGO),
143 	E(PROC_TGID_CMDLINE,   "cmdline", S_IFREG|S_IRUGO),
144 	E(PROC_TGID_STAT,      "stat",    S_IFREG|S_IRUGO),
145 	E(PROC_TGID_STATM,     "statm",   S_IFREG|S_IRUGO),
146 	E(PROC_TGID_MAPS,      "maps",    S_IFREG|S_IRUGO),
147 	E(PROC_TGID_MEM,       "mem",     S_IFREG|S_IRUSR|S_IWUSR),
148 #ifdef CONFIG_SECCOMP
149 	E(PROC_TGID_SECCOMP,   "seccomp", S_IFREG|S_IRUSR|S_IWUSR),
150 #endif
151 	E(PROC_TGID_CWD,       "cwd",     S_IFLNK|S_IRWXUGO),
152 	E(PROC_TGID_ROOT,      "root",    S_IFLNK|S_IRWXUGO),
153 	E(PROC_TGID_EXE,       "exe",     S_IFLNK|S_IRWXUGO),
154 	E(PROC_TGID_MOUNTS,    "mounts",  S_IFREG|S_IRUGO),
155 #ifdef CONFIG_SECURITY
156 	E(PROC_TGID_ATTR,      "attr",    S_IFDIR|S_IRUGO|S_IXUGO),
157 #endif
158 #ifdef CONFIG_KALLSYMS
159 	E(PROC_TGID_WCHAN,     "wchan",   S_IFREG|S_IRUGO),
160 #endif
161 #ifdef CONFIG_SCHEDSTATS
162 	E(PROC_TGID_SCHEDSTAT, "schedstat", S_IFREG|S_IRUGO),
163 #endif
164 #ifdef CONFIG_CPUSETS
165 	E(PROC_TGID_CPUSET,    "cpuset",  S_IFREG|S_IRUGO),
166 #endif
167 	E(PROC_TGID_OOM_SCORE, "oom_score",S_IFREG|S_IRUGO),
168 	E(PROC_TGID_OOM_ADJUST,"oom_adj", S_IFREG|S_IRUGO|S_IWUSR),
169 #ifdef CONFIG_AUDITSYSCALL
170 	E(PROC_TGID_LOGINUID, "loginuid", S_IFREG|S_IWUSR|S_IRUGO),
171 #endif
172 	{0,0,NULL,0}
173 };
174 static struct pid_entry tid_base_stuff[] = {
175 	E(PROC_TID_FD,         "fd",      S_IFDIR|S_IRUSR|S_IXUSR),
176 	E(PROC_TID_ENVIRON,    "environ", S_IFREG|S_IRUSR),
177 	E(PROC_TID_AUXV,       "auxv",	  S_IFREG|S_IRUSR),
178 	E(PROC_TID_STATUS,     "status",  S_IFREG|S_IRUGO),
179 	E(PROC_TID_CMDLINE,    "cmdline", S_IFREG|S_IRUGO),
180 	E(PROC_TID_STAT,       "stat",    S_IFREG|S_IRUGO),
181 	E(PROC_TID_STATM,      "statm",   S_IFREG|S_IRUGO),
182 	E(PROC_TID_MAPS,       "maps",    S_IFREG|S_IRUGO),
183 	E(PROC_TID_MEM,        "mem",     S_IFREG|S_IRUSR|S_IWUSR),
184 #ifdef CONFIG_SECCOMP
185 	E(PROC_TID_SECCOMP,    "seccomp", S_IFREG|S_IRUSR|S_IWUSR),
186 #endif
187 	E(PROC_TID_CWD,        "cwd",     S_IFLNK|S_IRWXUGO),
188 	E(PROC_TID_ROOT,       "root",    S_IFLNK|S_IRWXUGO),
189 	E(PROC_TID_EXE,        "exe",     S_IFLNK|S_IRWXUGO),
190 	E(PROC_TID_MOUNTS,     "mounts",  S_IFREG|S_IRUGO),
191 #ifdef CONFIG_SECURITY
192 	E(PROC_TID_ATTR,       "attr",    S_IFDIR|S_IRUGO|S_IXUGO),
193 #endif
194 #ifdef CONFIG_KALLSYMS
195 	E(PROC_TID_WCHAN,      "wchan",   S_IFREG|S_IRUGO),
196 #endif
197 #ifdef CONFIG_SCHEDSTATS
198 	E(PROC_TID_SCHEDSTAT, "schedstat",S_IFREG|S_IRUGO),
199 #endif
200 #ifdef CONFIG_CPUSETS
201 	E(PROC_TID_CPUSET,     "cpuset",  S_IFREG|S_IRUGO),
202 #endif
203 	E(PROC_TID_OOM_SCORE,  "oom_score",S_IFREG|S_IRUGO),
204 	E(PROC_TID_OOM_ADJUST, "oom_adj", S_IFREG|S_IRUGO|S_IWUSR),
205 #ifdef CONFIG_AUDITSYSCALL
206 	E(PROC_TID_LOGINUID, "loginuid", S_IFREG|S_IWUSR|S_IRUGO),
207 #endif
208 	{0,0,NULL,0}
209 };
210 
211 #ifdef CONFIG_SECURITY
212 static struct pid_entry tgid_attr_stuff[] = {
213 	E(PROC_TGID_ATTR_CURRENT,  "current",  S_IFREG|S_IRUGO|S_IWUGO),
214 	E(PROC_TGID_ATTR_PREV,     "prev",     S_IFREG|S_IRUGO),
215 	E(PROC_TGID_ATTR_EXEC,     "exec",     S_IFREG|S_IRUGO|S_IWUGO),
216 	E(PROC_TGID_ATTR_FSCREATE, "fscreate", S_IFREG|S_IRUGO|S_IWUGO),
217 	{0,0,NULL,0}
218 };
219 static struct pid_entry tid_attr_stuff[] = {
220 	E(PROC_TID_ATTR_CURRENT,   "current",  S_IFREG|S_IRUGO|S_IWUGO),
221 	E(PROC_TID_ATTR_PREV,      "prev",     S_IFREG|S_IRUGO),
222 	E(PROC_TID_ATTR_EXEC,      "exec",     S_IFREG|S_IRUGO|S_IWUGO),
223 	E(PROC_TID_ATTR_FSCREATE,  "fscreate", S_IFREG|S_IRUGO|S_IWUGO),
224 	{0,0,NULL,0}
225 };
226 #endif
227 
228 #undef E
229 
230 static int proc_fd_link(struct inode *inode, struct dentry **dentry, struct vfsmount **mnt)
231 {
232 	struct task_struct *task = proc_task(inode);
233 	struct files_struct *files;
234 	struct file *file;
235 	int fd = proc_type(inode) - PROC_TID_FD_DIR;
236 
237 	files = get_files_struct(task);
238 	if (files) {
239 		spin_lock(&files->file_lock);
240 		file = fcheck_files(files, fd);
241 		if (file) {
242 			*mnt = mntget(file->f_vfsmnt);
243 			*dentry = dget(file->f_dentry);
244 			spin_unlock(&files->file_lock);
245 			put_files_struct(files);
246 			return 0;
247 		}
248 		spin_unlock(&files->file_lock);
249 		put_files_struct(files);
250 	}
251 	return -ENOENT;
252 }
253 
254 static int proc_cwd_link(struct inode *inode, struct dentry **dentry, struct vfsmount **mnt)
255 {
256 	struct fs_struct *fs;
257 	int result = -ENOENT;
258 	task_lock(proc_task(inode));
259 	fs = proc_task(inode)->fs;
260 	if(fs)
261 		atomic_inc(&fs->count);
262 	task_unlock(proc_task(inode));
263 	if (fs) {
264 		read_lock(&fs->lock);
265 		*mnt = mntget(fs->pwdmnt);
266 		*dentry = dget(fs->pwd);
267 		read_unlock(&fs->lock);
268 		result = 0;
269 		put_fs_struct(fs);
270 	}
271 	return result;
272 }
273 
274 static int proc_root_link(struct inode *inode, struct dentry **dentry, struct vfsmount **mnt)
275 {
276 	struct fs_struct *fs;
277 	int result = -ENOENT;
278 	task_lock(proc_task(inode));
279 	fs = proc_task(inode)->fs;
280 	if(fs)
281 		atomic_inc(&fs->count);
282 	task_unlock(proc_task(inode));
283 	if (fs) {
284 		read_lock(&fs->lock);
285 		*mnt = mntget(fs->rootmnt);
286 		*dentry = dget(fs->root);
287 		read_unlock(&fs->lock);
288 		result = 0;
289 		put_fs_struct(fs);
290 	}
291 	return result;
292 }
293 
294 #define MAY_PTRACE(task) \
295 	(task == current || \
296 	(task->parent == current && \
297 	(task->ptrace & PT_PTRACED) && \
298 	 (task->state == TASK_STOPPED || task->state == TASK_TRACED) && \
299 	 security_ptrace(current,task) == 0))
300 
301 static int may_ptrace_attach(struct task_struct *task)
302 {
303 	int retval = 0;
304 
305 	task_lock(task);
306 
307 	if (!task->mm)
308 		goto out;
309 	if (((current->uid != task->euid) ||
310 	     (current->uid != task->suid) ||
311 	     (current->uid != task->uid) ||
312 	     (current->gid != task->egid) ||
313 	     (current->gid != task->sgid) ||
314 	     (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
315 		goto out;
316 	rmb();
317 	if (task->mm->dumpable != 1 && !capable(CAP_SYS_PTRACE))
318 		goto out;
319 	if (security_ptrace(current, task))
320 		goto out;
321 
322 	retval = 1;
323 out:
324 	task_unlock(task);
325 	return retval;
326 }
327 
328 static int proc_pid_environ(struct task_struct *task, char * buffer)
329 {
330 	int res = 0;
331 	struct mm_struct *mm = get_task_mm(task);
332 	if (mm) {
333 		unsigned int len = mm->env_end - mm->env_start;
334 		if (len > PAGE_SIZE)
335 			len = PAGE_SIZE;
336 		res = access_process_vm(task, mm->env_start, buffer, len, 0);
337 		if (!may_ptrace_attach(task))
338 			res = -ESRCH;
339 		mmput(mm);
340 	}
341 	return res;
342 }
343 
344 static int proc_pid_cmdline(struct task_struct *task, char * buffer)
345 {
346 	int res = 0;
347 	unsigned int len;
348 	struct mm_struct *mm = get_task_mm(task);
349 	if (!mm)
350 		goto out;
351 	if (!mm->arg_end)
352 		goto out_mm;	/* Shh! No looking before we're done */
353 
354  	len = mm->arg_end - mm->arg_start;
355 
356 	if (len > PAGE_SIZE)
357 		len = PAGE_SIZE;
358 
359 	res = access_process_vm(task, mm->arg_start, buffer, len, 0);
360 
361 	// If the nul at the end of args has been overwritten, then
362 	// assume application is using setproctitle(3).
363 	if (res > 0 && buffer[res-1] != '\0' && len < PAGE_SIZE) {
364 		len = strnlen(buffer, res);
365 		if (len < res) {
366 		    res = len;
367 		} else {
368 			len = mm->env_end - mm->env_start;
369 			if (len > PAGE_SIZE - res)
370 				len = PAGE_SIZE - res;
371 			res += access_process_vm(task, mm->env_start, buffer+res, len, 0);
372 			res = strnlen(buffer, res);
373 		}
374 	}
375 out_mm:
376 	mmput(mm);
377 out:
378 	return res;
379 }
380 
381 static int proc_pid_auxv(struct task_struct *task, char *buffer)
382 {
383 	int res = 0;
384 	struct mm_struct *mm = get_task_mm(task);
385 	if (mm) {
386 		unsigned int nwords = 0;
387 		do
388 			nwords += 2;
389 		while (mm->saved_auxv[nwords - 2] != 0); /* AT_NULL */
390 		res = nwords * sizeof(mm->saved_auxv[0]);
391 		if (res > PAGE_SIZE)
392 			res = PAGE_SIZE;
393 		memcpy(buffer, mm->saved_auxv, res);
394 		mmput(mm);
395 	}
396 	return res;
397 }
398 
399 
400 #ifdef CONFIG_KALLSYMS
401 /*
402  * Provides a wchan file via kallsyms in a proper one-value-per-file format.
403  * Returns the resolved symbol.  If that fails, simply return the address.
404  */
405 static int proc_pid_wchan(struct task_struct *task, char *buffer)
406 {
407 	char *modname;
408 	const char *sym_name;
409 	unsigned long wchan, size, offset;
410 	char namebuf[KSYM_NAME_LEN+1];
411 
412 	wchan = get_wchan(task);
413 
414 	sym_name = kallsyms_lookup(wchan, &size, &offset, &modname, namebuf);
415 	if (sym_name)
416 		return sprintf(buffer, "%s", sym_name);
417 	return sprintf(buffer, "%lu", wchan);
418 }
419 #endif /* CONFIG_KALLSYMS */
420 
421 #ifdef CONFIG_SCHEDSTATS
422 /*
423  * Provides /proc/PID/schedstat
424  */
425 static int proc_pid_schedstat(struct task_struct *task, char *buffer)
426 {
427 	return sprintf(buffer, "%lu %lu %lu\n",
428 			task->sched_info.cpu_time,
429 			task->sched_info.run_delay,
430 			task->sched_info.pcnt);
431 }
432 #endif
433 
434 /* The badness from the OOM killer */
435 unsigned long badness(struct task_struct *p, unsigned long uptime);
436 static int proc_oom_score(struct task_struct *task, char *buffer)
437 {
438 	unsigned long points;
439 	struct timespec uptime;
440 
441 	do_posix_clock_monotonic_gettime(&uptime);
442 	points = badness(task, uptime.tv_sec);
443 	return sprintf(buffer, "%lu\n", points);
444 }
445 
446 /************************************************************************/
447 /*                       Here the fs part begins                        */
448 /************************************************************************/
449 
450 /* permission checks */
451 
452 static int proc_check_root(struct inode *inode)
453 {
454 	struct dentry *de, *base, *root;
455 	struct vfsmount *our_vfsmnt, *vfsmnt, *mnt;
456 	int res = 0;
457 
458 	if (proc_root_link(inode, &root, &vfsmnt)) /* Ewww... */
459 		return -ENOENT;
460 	read_lock(&current->fs->lock);
461 	our_vfsmnt = mntget(current->fs->rootmnt);
462 	base = dget(current->fs->root);
463 	read_unlock(&current->fs->lock);
464 
465 	spin_lock(&vfsmount_lock);
466 	de = root;
467 	mnt = vfsmnt;
468 
469 	while (vfsmnt != our_vfsmnt) {
470 		if (vfsmnt == vfsmnt->mnt_parent)
471 			goto out;
472 		de = vfsmnt->mnt_mountpoint;
473 		vfsmnt = vfsmnt->mnt_parent;
474 	}
475 
476 	if (!is_subdir(de, base))
477 		goto out;
478 	spin_unlock(&vfsmount_lock);
479 
480 exit:
481 	dput(base);
482 	mntput(our_vfsmnt);
483 	dput(root);
484 	mntput(mnt);
485 	return res;
486 out:
487 	spin_unlock(&vfsmount_lock);
488 	res = -EACCES;
489 	goto exit;
490 }
491 
492 static int proc_permission(struct inode *inode, int mask, struct nameidata *nd)
493 {
494 	if (generic_permission(inode, mask, NULL) != 0)
495 		return -EACCES;
496 	return proc_check_root(inode);
497 }
498 
499 extern struct seq_operations proc_pid_maps_op;
500 static int maps_open(struct inode *inode, struct file *file)
501 {
502 	struct task_struct *task = proc_task(inode);
503 	int ret = seq_open(file, &proc_pid_maps_op);
504 	if (!ret) {
505 		struct seq_file *m = file->private_data;
506 		m->private = task;
507 	}
508 	return ret;
509 }
510 
511 static struct file_operations proc_maps_operations = {
512 	.open		= maps_open,
513 	.read		= seq_read,
514 	.llseek		= seq_lseek,
515 	.release	= seq_release,
516 };
517 
518 extern struct seq_operations mounts_op;
519 static int mounts_open(struct inode *inode, struct file *file)
520 {
521 	struct task_struct *task = proc_task(inode);
522 	int ret = seq_open(file, &mounts_op);
523 
524 	if (!ret) {
525 		struct seq_file *m = file->private_data;
526 		struct namespace *namespace;
527 		task_lock(task);
528 		namespace = task->namespace;
529 		if (namespace)
530 			get_namespace(namespace);
531 		task_unlock(task);
532 
533 		if (namespace)
534 			m->private = namespace;
535 		else {
536 			seq_release(inode, file);
537 			ret = -EINVAL;
538 		}
539 	}
540 	return ret;
541 }
542 
543 static int mounts_release(struct inode *inode, struct file *file)
544 {
545 	struct seq_file *m = file->private_data;
546 	struct namespace *namespace = m->private;
547 	put_namespace(namespace);
548 	return seq_release(inode, file);
549 }
550 
551 static struct file_operations proc_mounts_operations = {
552 	.open		= mounts_open,
553 	.read		= seq_read,
554 	.llseek		= seq_lseek,
555 	.release	= mounts_release,
556 };
557 
558 #define PROC_BLOCK_SIZE	(3*1024)		/* 4K page size but our output routines use some slack for overruns */
559 
560 static ssize_t proc_info_read(struct file * file, char __user * buf,
561 			  size_t count, loff_t *ppos)
562 {
563 	struct inode * inode = file->f_dentry->d_inode;
564 	unsigned long page;
565 	ssize_t length;
566 	struct task_struct *task = proc_task(inode);
567 
568 	if (count > PROC_BLOCK_SIZE)
569 		count = PROC_BLOCK_SIZE;
570 	if (!(page = __get_free_page(GFP_KERNEL)))
571 		return -ENOMEM;
572 
573 	length = PROC_I(inode)->op.proc_read(task, (char*)page);
574 
575 	if (length >= 0)
576 		length = simple_read_from_buffer(buf, count, ppos, (char *)page, length);
577 	free_page(page);
578 	return length;
579 }
580 
581 static struct file_operations proc_info_file_operations = {
582 	.read		= proc_info_read,
583 };
584 
585 static int mem_open(struct inode* inode, struct file* file)
586 {
587 	file->private_data = (void*)((long)current->self_exec_id);
588 	return 0;
589 }
590 
591 static ssize_t mem_read(struct file * file, char __user * buf,
592 			size_t count, loff_t *ppos)
593 {
594 	struct task_struct *task = proc_task(file->f_dentry->d_inode);
595 	char *page;
596 	unsigned long src = *ppos;
597 	int ret = -ESRCH;
598 	struct mm_struct *mm;
599 
600 	if (!MAY_PTRACE(task) || !may_ptrace_attach(task))
601 		goto out;
602 
603 	ret = -ENOMEM;
604 	page = (char *)__get_free_page(GFP_USER);
605 	if (!page)
606 		goto out;
607 
608 	ret = 0;
609 
610 	mm = get_task_mm(task);
611 	if (!mm)
612 		goto out_free;
613 
614 	ret = -EIO;
615 
616 	if (file->private_data != (void*)((long)current->self_exec_id))
617 		goto out_put;
618 
619 	ret = 0;
620 
621 	while (count > 0) {
622 		int this_len, retval;
623 
624 		this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
625 		retval = access_process_vm(task, src, page, this_len, 0);
626 		if (!retval || !MAY_PTRACE(task) || !may_ptrace_attach(task)) {
627 			if (!ret)
628 				ret = -EIO;
629 			break;
630 		}
631 
632 		if (copy_to_user(buf, page, retval)) {
633 			ret = -EFAULT;
634 			break;
635 		}
636 
637 		ret += retval;
638 		src += retval;
639 		buf += retval;
640 		count -= retval;
641 	}
642 	*ppos = src;
643 
644 out_put:
645 	mmput(mm);
646 out_free:
647 	free_page((unsigned long) page);
648 out:
649 	return ret;
650 }
651 
652 #define mem_write NULL
653 
654 #ifndef mem_write
655 /* This is a security hazard */
656 static ssize_t mem_write(struct file * file, const char * buf,
657 			 size_t count, loff_t *ppos)
658 {
659 	int copied = 0;
660 	char *page;
661 	struct task_struct *task = proc_task(file->f_dentry->d_inode);
662 	unsigned long dst = *ppos;
663 
664 	if (!MAY_PTRACE(task) || !may_ptrace_attach(task))
665 		return -ESRCH;
666 
667 	page = (char *)__get_free_page(GFP_USER);
668 	if (!page)
669 		return -ENOMEM;
670 
671 	while (count > 0) {
672 		int this_len, retval;
673 
674 		this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
675 		if (copy_from_user(page, buf, this_len)) {
676 			copied = -EFAULT;
677 			break;
678 		}
679 		retval = access_process_vm(task, dst, page, this_len, 1);
680 		if (!retval) {
681 			if (!copied)
682 				copied = -EIO;
683 			break;
684 		}
685 		copied += retval;
686 		buf += retval;
687 		dst += retval;
688 		count -= retval;
689 	}
690 	*ppos = dst;
691 	free_page((unsigned long) page);
692 	return copied;
693 }
694 #endif
695 
696 static loff_t mem_lseek(struct file * file, loff_t offset, int orig)
697 {
698 	switch (orig) {
699 	case 0:
700 		file->f_pos = offset;
701 		break;
702 	case 1:
703 		file->f_pos += offset;
704 		break;
705 	default:
706 		return -EINVAL;
707 	}
708 	force_successful_syscall_return();
709 	return file->f_pos;
710 }
711 
712 static struct file_operations proc_mem_operations = {
713 	.llseek		= mem_lseek,
714 	.read		= mem_read,
715 	.write		= mem_write,
716 	.open		= mem_open,
717 };
718 
719 static ssize_t oom_adjust_read(struct file *file, char __user *buf,
720 				size_t count, loff_t *ppos)
721 {
722 	struct task_struct *task = proc_task(file->f_dentry->d_inode);
723 	char buffer[8];
724 	size_t len;
725 	int oom_adjust = task->oomkilladj;
726 	loff_t __ppos = *ppos;
727 
728 	len = sprintf(buffer, "%i\n", oom_adjust);
729 	if (__ppos >= len)
730 		return 0;
731 	if (count > len-__ppos)
732 		count = len-__ppos;
733 	if (copy_to_user(buf, buffer + __ppos, count))
734 		return -EFAULT;
735 	*ppos = __ppos + count;
736 	return count;
737 }
738 
739 static ssize_t oom_adjust_write(struct file *file, const char __user *buf,
740 				size_t count, loff_t *ppos)
741 {
742 	struct task_struct *task = proc_task(file->f_dentry->d_inode);
743 	char buffer[8], *end;
744 	int oom_adjust;
745 
746 	if (!capable(CAP_SYS_RESOURCE))
747 		return -EPERM;
748 	memset(buffer, 0, 8);
749 	if (count > 6)
750 		count = 6;
751 	if (copy_from_user(buffer, buf, count))
752 		return -EFAULT;
753 	oom_adjust = simple_strtol(buffer, &end, 0);
754 	if ((oom_adjust < -16 || oom_adjust > 15) && oom_adjust != OOM_DISABLE)
755 		return -EINVAL;
756 	if (*end == '\n')
757 		end++;
758 	task->oomkilladj = oom_adjust;
759 	if (end - buffer == 0)
760 		return -EIO;
761 	return end - buffer;
762 }
763 
764 static struct file_operations proc_oom_adjust_operations = {
765 	.read		= oom_adjust_read,
766 	.write		= oom_adjust_write,
767 };
768 
769 static struct inode_operations proc_mem_inode_operations = {
770 	.permission	= proc_permission,
771 };
772 
773 #ifdef CONFIG_AUDITSYSCALL
774 #define TMPBUFLEN 21
775 static ssize_t proc_loginuid_read(struct file * file, char __user * buf,
776 				  size_t count, loff_t *ppos)
777 {
778 	struct inode * inode = file->f_dentry->d_inode;
779 	struct task_struct *task = proc_task(inode);
780 	ssize_t length;
781 	char tmpbuf[TMPBUFLEN];
782 
783 	length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
784 				audit_get_loginuid(task->audit_context));
785 	return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
786 }
787 
788 static ssize_t proc_loginuid_write(struct file * file, const char __user * buf,
789 				   size_t count, loff_t *ppos)
790 {
791 	struct inode * inode = file->f_dentry->d_inode;
792 	char *page, *tmp;
793 	ssize_t length;
794 	struct task_struct *task = proc_task(inode);
795 	uid_t loginuid;
796 
797 	if (!capable(CAP_AUDIT_CONTROL))
798 		return -EPERM;
799 
800 	if (current != task)
801 		return -EPERM;
802 
803 	if (count > PAGE_SIZE)
804 		count = PAGE_SIZE;
805 
806 	if (*ppos != 0) {
807 		/* No partial writes. */
808 		return -EINVAL;
809 	}
810 	page = (char*)__get_free_page(GFP_USER);
811 	if (!page)
812 		return -ENOMEM;
813 	length = -EFAULT;
814 	if (copy_from_user(page, buf, count))
815 		goto out_free_page;
816 
817 	loginuid = simple_strtoul(page, &tmp, 10);
818 	if (tmp == page) {
819 		length = -EINVAL;
820 		goto out_free_page;
821 
822 	}
823 	length = audit_set_loginuid(task, loginuid);
824 	if (likely(length == 0))
825 		length = count;
826 
827 out_free_page:
828 	free_page((unsigned long) page);
829 	return length;
830 }
831 
832 static struct file_operations proc_loginuid_operations = {
833 	.read		= proc_loginuid_read,
834 	.write		= proc_loginuid_write,
835 };
836 #endif
837 
838 #ifdef CONFIG_SECCOMP
839 static ssize_t seccomp_read(struct file *file, char __user *buf,
840 			    size_t count, loff_t *ppos)
841 {
842 	struct task_struct *tsk = proc_task(file->f_dentry->d_inode);
843 	char __buf[20];
844 	loff_t __ppos = *ppos;
845 	size_t len;
846 
847 	/* no need to print the trailing zero, so use only len */
848 	len = sprintf(__buf, "%u\n", tsk->seccomp.mode);
849 	if (__ppos >= len)
850 		return 0;
851 	if (count > len - __ppos)
852 		count = len - __ppos;
853 	if (copy_to_user(buf, __buf + __ppos, count))
854 		return -EFAULT;
855 	*ppos = __ppos + count;
856 	return count;
857 }
858 
859 static ssize_t seccomp_write(struct file *file, const char __user *buf,
860 			     size_t count, loff_t *ppos)
861 {
862 	struct task_struct *tsk = proc_task(file->f_dentry->d_inode);
863 	char __buf[20], *end;
864 	unsigned int seccomp_mode;
865 
866 	/* can set it only once to be even more secure */
867 	if (unlikely(tsk->seccomp.mode))
868 		return -EPERM;
869 
870 	memset(__buf, 0, sizeof(__buf));
871 	count = min(count, sizeof(__buf) - 1);
872 	if (copy_from_user(__buf, buf, count))
873 		return -EFAULT;
874 	seccomp_mode = simple_strtoul(__buf, &end, 0);
875 	if (*end == '\n')
876 		end++;
877 	if (seccomp_mode && seccomp_mode <= NR_SECCOMP_MODES) {
878 		tsk->seccomp.mode = seccomp_mode;
879 		set_tsk_thread_flag(tsk, TIF_SECCOMP);
880 	} else
881 		return -EINVAL;
882 	if (unlikely(!(end - __buf)))
883 		return -EIO;
884 	return end - __buf;
885 }
886 
887 static struct file_operations proc_seccomp_operations = {
888 	.read		= seccomp_read,
889 	.write		= seccomp_write,
890 };
891 #endif /* CONFIG_SECCOMP */
892 
893 static int proc_pid_follow_link(struct dentry *dentry, struct nameidata *nd)
894 {
895 	struct inode *inode = dentry->d_inode;
896 	int error = -EACCES;
897 
898 	/* We don't need a base pointer in the /proc filesystem */
899 	path_release(nd);
900 
901 	if (current->fsuid != inode->i_uid && !capable(CAP_DAC_OVERRIDE))
902 		goto out;
903 	error = proc_check_root(inode);
904 	if (error)
905 		goto out;
906 
907 	error = PROC_I(inode)->op.proc_get_link(inode, &nd->dentry, &nd->mnt);
908 	nd->last_type = LAST_BIND;
909 out:
910 	return error;
911 }
912 
913 static int do_proc_readlink(struct dentry *dentry, struct vfsmount *mnt,
914 			    char __user *buffer, int buflen)
915 {
916 	struct inode * inode;
917 	char *tmp = (char*)__get_free_page(GFP_KERNEL), *path;
918 	int len;
919 
920 	if (!tmp)
921 		return -ENOMEM;
922 
923 	inode = dentry->d_inode;
924 	path = d_path(dentry, mnt, tmp, PAGE_SIZE);
925 	len = PTR_ERR(path);
926 	if (IS_ERR(path))
927 		goto out;
928 	len = tmp + PAGE_SIZE - 1 - path;
929 
930 	if (len > buflen)
931 		len = buflen;
932 	if (copy_to_user(buffer, path, len))
933 		len = -EFAULT;
934  out:
935 	free_page((unsigned long)tmp);
936 	return len;
937 }
938 
939 static int proc_pid_readlink(struct dentry * dentry, char __user * buffer, int buflen)
940 {
941 	int error = -EACCES;
942 	struct inode *inode = dentry->d_inode;
943 	struct dentry *de;
944 	struct vfsmount *mnt = NULL;
945 
946 	lock_kernel();
947 
948 	if (current->fsuid != inode->i_uid && !capable(CAP_DAC_OVERRIDE))
949 		goto out;
950 	error = proc_check_root(inode);
951 	if (error)
952 		goto out;
953 
954 	error = PROC_I(inode)->op.proc_get_link(inode, &de, &mnt);
955 	if (error)
956 		goto out;
957 
958 	error = do_proc_readlink(de, mnt, buffer, buflen);
959 	dput(de);
960 	mntput(mnt);
961 out:
962 	unlock_kernel();
963 	return error;
964 }
965 
966 static struct inode_operations proc_pid_link_inode_operations = {
967 	.readlink	= proc_pid_readlink,
968 	.follow_link	= proc_pid_follow_link
969 };
970 
971 #define NUMBUF 10
972 
973 static int proc_readfd(struct file * filp, void * dirent, filldir_t filldir)
974 {
975 	struct inode *inode = filp->f_dentry->d_inode;
976 	struct task_struct *p = proc_task(inode);
977 	unsigned int fd, tid, ino;
978 	int retval;
979 	char buf[NUMBUF];
980 	struct files_struct * files;
981 
982 	retval = -ENOENT;
983 	if (!pid_alive(p))
984 		goto out;
985 	retval = 0;
986 	tid = p->pid;
987 
988 	fd = filp->f_pos;
989 	switch (fd) {
990 		case 0:
991 			if (filldir(dirent, ".", 1, 0, inode->i_ino, DT_DIR) < 0)
992 				goto out;
993 			filp->f_pos++;
994 		case 1:
995 			ino = fake_ino(tid, PROC_TID_INO);
996 			if (filldir(dirent, "..", 2, 1, ino, DT_DIR) < 0)
997 				goto out;
998 			filp->f_pos++;
999 		default:
1000 			files = get_files_struct(p);
1001 			if (!files)
1002 				goto out;
1003 			spin_lock(&files->file_lock);
1004 			for (fd = filp->f_pos-2;
1005 			     fd < files->max_fds;
1006 			     fd++, filp->f_pos++) {
1007 				unsigned int i,j;
1008 
1009 				if (!fcheck_files(files, fd))
1010 					continue;
1011 				spin_unlock(&files->file_lock);
1012 
1013 				j = NUMBUF;
1014 				i = fd;
1015 				do {
1016 					j--;
1017 					buf[j] = '0' + (i % 10);
1018 					i /= 10;
1019 				} while (i);
1020 
1021 				ino = fake_ino(tid, PROC_TID_FD_DIR + fd);
1022 				if (filldir(dirent, buf+j, NUMBUF-j, fd+2, ino, DT_LNK) < 0) {
1023 					spin_lock(&files->file_lock);
1024 					break;
1025 				}
1026 				spin_lock(&files->file_lock);
1027 			}
1028 			spin_unlock(&files->file_lock);
1029 			put_files_struct(files);
1030 	}
1031 out:
1032 	return retval;
1033 }
1034 
1035 static int proc_pident_readdir(struct file *filp,
1036 		void *dirent, filldir_t filldir,
1037 		struct pid_entry *ents, unsigned int nents)
1038 {
1039 	int i;
1040 	int pid;
1041 	struct dentry *dentry = filp->f_dentry;
1042 	struct inode *inode = dentry->d_inode;
1043 	struct pid_entry *p;
1044 	ino_t ino;
1045 	int ret;
1046 
1047 	ret = -ENOENT;
1048 	if (!pid_alive(proc_task(inode)))
1049 		goto out;
1050 
1051 	ret = 0;
1052 	pid = proc_task(inode)->pid;
1053 	i = filp->f_pos;
1054 	switch (i) {
1055 	case 0:
1056 		ino = inode->i_ino;
1057 		if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
1058 			goto out;
1059 		i++;
1060 		filp->f_pos++;
1061 		/* fall through */
1062 	case 1:
1063 		ino = parent_ino(dentry);
1064 		if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
1065 			goto out;
1066 		i++;
1067 		filp->f_pos++;
1068 		/* fall through */
1069 	default:
1070 		i -= 2;
1071 		if (i >= nents) {
1072 			ret = 1;
1073 			goto out;
1074 		}
1075 		p = ents + i;
1076 		while (p->name) {
1077 			if (filldir(dirent, p->name, p->len, filp->f_pos,
1078 				    fake_ino(pid, p->type), p->mode >> 12) < 0)
1079 				goto out;
1080 			filp->f_pos++;
1081 			p++;
1082 		}
1083 	}
1084 
1085 	ret = 1;
1086 out:
1087 	return ret;
1088 }
1089 
1090 static int proc_tgid_base_readdir(struct file * filp,
1091 			     void * dirent, filldir_t filldir)
1092 {
1093 	return proc_pident_readdir(filp,dirent,filldir,
1094 				   tgid_base_stuff,ARRAY_SIZE(tgid_base_stuff));
1095 }
1096 
1097 static int proc_tid_base_readdir(struct file * filp,
1098 			     void * dirent, filldir_t filldir)
1099 {
1100 	return proc_pident_readdir(filp,dirent,filldir,
1101 				   tid_base_stuff,ARRAY_SIZE(tid_base_stuff));
1102 }
1103 
1104 /* building an inode */
1105 
1106 static int task_dumpable(struct task_struct *task)
1107 {
1108 	int dumpable = 0;
1109 	struct mm_struct *mm;
1110 
1111 	task_lock(task);
1112 	mm = task->mm;
1113 	if (mm)
1114 		dumpable = mm->dumpable;
1115 	task_unlock(task);
1116 	if(dumpable == 1)
1117 		return 1;
1118 	return 0;
1119 }
1120 
1121 
1122 static struct inode *proc_pid_make_inode(struct super_block * sb, struct task_struct *task, int ino)
1123 {
1124 	struct inode * inode;
1125 	struct proc_inode *ei;
1126 
1127 	/* We need a new inode */
1128 
1129 	inode = new_inode(sb);
1130 	if (!inode)
1131 		goto out;
1132 
1133 	/* Common stuff */
1134 	ei = PROC_I(inode);
1135 	ei->task = NULL;
1136 	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
1137 	inode->i_ino = fake_ino(task->pid, ino);
1138 
1139 	if (!pid_alive(task))
1140 		goto out_unlock;
1141 
1142 	/*
1143 	 * grab the reference to task.
1144 	 */
1145 	get_task_struct(task);
1146 	ei->task = task;
1147 	ei->type = ino;
1148 	inode->i_uid = 0;
1149 	inode->i_gid = 0;
1150 	if (ino == PROC_TGID_INO || ino == PROC_TID_INO || task_dumpable(task)) {
1151 		inode->i_uid = task->euid;
1152 		inode->i_gid = task->egid;
1153 	}
1154 	security_task_to_inode(task, inode);
1155 
1156 out:
1157 	return inode;
1158 
1159 out_unlock:
1160 	ei->pde = NULL;
1161 	iput(inode);
1162 	return NULL;
1163 }
1164 
1165 /* dentry stuff */
1166 
1167 /*
1168  *	Exceptional case: normally we are not allowed to unhash a busy
1169  * directory. In this case, however, we can do it - no aliasing problems
1170  * due to the way we treat inodes.
1171  *
1172  * Rewrite the inode's ownerships here because the owning task may have
1173  * performed a setuid(), etc.
1174  */
1175 static int pid_revalidate(struct dentry *dentry, struct nameidata *nd)
1176 {
1177 	struct inode *inode = dentry->d_inode;
1178 	struct task_struct *task = proc_task(inode);
1179 	if (pid_alive(task)) {
1180 		if (proc_type(inode) == PROC_TGID_INO || proc_type(inode) == PROC_TID_INO || task_dumpable(task)) {
1181 			inode->i_uid = task->euid;
1182 			inode->i_gid = task->egid;
1183 		} else {
1184 			inode->i_uid = 0;
1185 			inode->i_gid = 0;
1186 		}
1187 		security_task_to_inode(task, inode);
1188 		return 1;
1189 	}
1190 	d_drop(dentry);
1191 	return 0;
1192 }
1193 
1194 static int tid_fd_revalidate(struct dentry *dentry, struct nameidata *nd)
1195 {
1196 	struct inode *inode = dentry->d_inode;
1197 	struct task_struct *task = proc_task(inode);
1198 	int fd = proc_type(inode) - PROC_TID_FD_DIR;
1199 	struct files_struct *files;
1200 
1201 	files = get_files_struct(task);
1202 	if (files) {
1203 		spin_lock(&files->file_lock);
1204 		if (fcheck_files(files, fd)) {
1205 			spin_unlock(&files->file_lock);
1206 			put_files_struct(files);
1207 			if (task_dumpable(task)) {
1208 				inode->i_uid = task->euid;
1209 				inode->i_gid = task->egid;
1210 			} else {
1211 				inode->i_uid = 0;
1212 				inode->i_gid = 0;
1213 			}
1214 			security_task_to_inode(task, inode);
1215 			return 1;
1216 		}
1217 		spin_unlock(&files->file_lock);
1218 		put_files_struct(files);
1219 	}
1220 	d_drop(dentry);
1221 	return 0;
1222 }
1223 
1224 static void pid_base_iput(struct dentry *dentry, struct inode *inode)
1225 {
1226 	struct task_struct *task = proc_task(inode);
1227 	spin_lock(&task->proc_lock);
1228 	if (task->proc_dentry == dentry)
1229 		task->proc_dentry = NULL;
1230 	spin_unlock(&task->proc_lock);
1231 	iput(inode);
1232 }
1233 
1234 static int pid_delete_dentry(struct dentry * dentry)
1235 {
1236 	/* Is the task we represent dead?
1237 	 * If so, then don't put the dentry on the lru list,
1238 	 * kill it immediately.
1239 	 */
1240 	return !pid_alive(proc_task(dentry->d_inode));
1241 }
1242 
1243 static struct dentry_operations tid_fd_dentry_operations =
1244 {
1245 	.d_revalidate	= tid_fd_revalidate,
1246 	.d_delete	= pid_delete_dentry,
1247 };
1248 
1249 static struct dentry_operations pid_dentry_operations =
1250 {
1251 	.d_revalidate	= pid_revalidate,
1252 	.d_delete	= pid_delete_dentry,
1253 };
1254 
1255 static struct dentry_operations pid_base_dentry_operations =
1256 {
1257 	.d_revalidate	= pid_revalidate,
1258 	.d_iput		= pid_base_iput,
1259 	.d_delete	= pid_delete_dentry,
1260 };
1261 
1262 /* Lookups */
1263 
1264 static unsigned name_to_int(struct dentry *dentry)
1265 {
1266 	const char *name = dentry->d_name.name;
1267 	int len = dentry->d_name.len;
1268 	unsigned n = 0;
1269 
1270 	if (len > 1 && *name == '0')
1271 		goto out;
1272 	while (len-- > 0) {
1273 		unsigned c = *name++ - '0';
1274 		if (c > 9)
1275 			goto out;
1276 		if (n >= (~0U-9)/10)
1277 			goto out;
1278 		n *= 10;
1279 		n += c;
1280 	}
1281 	return n;
1282 out:
1283 	return ~0U;
1284 }
1285 
1286 /* SMP-safe */
1287 static struct dentry *proc_lookupfd(struct inode * dir, struct dentry * dentry, struct nameidata *nd)
1288 {
1289 	struct task_struct *task = proc_task(dir);
1290 	unsigned fd = name_to_int(dentry);
1291 	struct file * file;
1292 	struct files_struct * files;
1293 	struct inode *inode;
1294 	struct proc_inode *ei;
1295 
1296 	if (fd == ~0U)
1297 		goto out;
1298 	if (!pid_alive(task))
1299 		goto out;
1300 
1301 	inode = proc_pid_make_inode(dir->i_sb, task, PROC_TID_FD_DIR+fd);
1302 	if (!inode)
1303 		goto out;
1304 	ei = PROC_I(inode);
1305 	files = get_files_struct(task);
1306 	if (!files)
1307 		goto out_unlock;
1308 	inode->i_mode = S_IFLNK;
1309 	spin_lock(&files->file_lock);
1310 	file = fcheck_files(files, fd);
1311 	if (!file)
1312 		goto out_unlock2;
1313 	if (file->f_mode & 1)
1314 		inode->i_mode |= S_IRUSR | S_IXUSR;
1315 	if (file->f_mode & 2)
1316 		inode->i_mode |= S_IWUSR | S_IXUSR;
1317 	spin_unlock(&files->file_lock);
1318 	put_files_struct(files);
1319 	inode->i_op = &proc_pid_link_inode_operations;
1320 	inode->i_size = 64;
1321 	ei->op.proc_get_link = proc_fd_link;
1322 	dentry->d_op = &tid_fd_dentry_operations;
1323 	d_add(dentry, inode);
1324 	return NULL;
1325 
1326 out_unlock2:
1327 	spin_unlock(&files->file_lock);
1328 	put_files_struct(files);
1329 out_unlock:
1330 	iput(inode);
1331 out:
1332 	return ERR_PTR(-ENOENT);
1333 }
1334 
1335 static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldir);
1336 static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd);
1337 
1338 static struct file_operations proc_fd_operations = {
1339 	.read		= generic_read_dir,
1340 	.readdir	= proc_readfd,
1341 };
1342 
1343 static struct file_operations proc_task_operations = {
1344 	.read		= generic_read_dir,
1345 	.readdir	= proc_task_readdir,
1346 };
1347 
1348 /*
1349  * proc directories can do almost nothing..
1350  */
1351 static struct inode_operations proc_fd_inode_operations = {
1352 	.lookup		= proc_lookupfd,
1353 	.permission	= proc_permission,
1354 };
1355 
1356 static struct inode_operations proc_task_inode_operations = {
1357 	.lookup		= proc_task_lookup,
1358 	.permission	= proc_permission,
1359 };
1360 
1361 #ifdef CONFIG_SECURITY
1362 static ssize_t proc_pid_attr_read(struct file * file, char __user * buf,
1363 				  size_t count, loff_t *ppos)
1364 {
1365 	struct inode * inode = file->f_dentry->d_inode;
1366 	unsigned long page;
1367 	ssize_t length;
1368 	struct task_struct *task = proc_task(inode);
1369 
1370 	if (count > PAGE_SIZE)
1371 		count = PAGE_SIZE;
1372 	if (!(page = __get_free_page(GFP_KERNEL)))
1373 		return -ENOMEM;
1374 
1375 	length = security_getprocattr(task,
1376 				      (char*)file->f_dentry->d_name.name,
1377 				      (void*)page, count);
1378 	if (length >= 0)
1379 		length = simple_read_from_buffer(buf, count, ppos, (char *)page, length);
1380 	free_page(page);
1381 	return length;
1382 }
1383 
1384 static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
1385 				   size_t count, loff_t *ppos)
1386 {
1387 	struct inode * inode = file->f_dentry->d_inode;
1388 	char *page;
1389 	ssize_t length;
1390 	struct task_struct *task = proc_task(inode);
1391 
1392 	if (count > PAGE_SIZE)
1393 		count = PAGE_SIZE;
1394 	if (*ppos != 0) {
1395 		/* No partial writes. */
1396 		return -EINVAL;
1397 	}
1398 	page = (char*)__get_free_page(GFP_USER);
1399 	if (!page)
1400 		return -ENOMEM;
1401 	length = -EFAULT;
1402 	if (copy_from_user(page, buf, count))
1403 		goto out;
1404 
1405 	length = security_setprocattr(task,
1406 				      (char*)file->f_dentry->d_name.name,
1407 				      (void*)page, count);
1408 out:
1409 	free_page((unsigned long) page);
1410 	return length;
1411 }
1412 
1413 static struct file_operations proc_pid_attr_operations = {
1414 	.read		= proc_pid_attr_read,
1415 	.write		= proc_pid_attr_write,
1416 };
1417 
1418 static struct file_operations proc_tid_attr_operations;
1419 static struct inode_operations proc_tid_attr_inode_operations;
1420 static struct file_operations proc_tgid_attr_operations;
1421 static struct inode_operations proc_tgid_attr_inode_operations;
1422 #endif
1423 
1424 static int get_tid_list(int index, unsigned int *tids, struct inode *dir);
1425 
1426 /* SMP-safe */
1427 static struct dentry *proc_pident_lookup(struct inode *dir,
1428 					 struct dentry *dentry,
1429 					 struct pid_entry *ents)
1430 {
1431 	struct inode *inode;
1432 	int error;
1433 	struct task_struct *task = proc_task(dir);
1434 	struct pid_entry *p;
1435 	struct proc_inode *ei;
1436 
1437 	error = -ENOENT;
1438 	inode = NULL;
1439 
1440 	if (!pid_alive(task))
1441 		goto out;
1442 
1443 	for (p = ents; p->name; p++) {
1444 		if (p->len != dentry->d_name.len)
1445 			continue;
1446 		if (!memcmp(dentry->d_name.name, p->name, p->len))
1447 			break;
1448 	}
1449 	if (!p->name)
1450 		goto out;
1451 
1452 	error = -EINVAL;
1453 	inode = proc_pid_make_inode(dir->i_sb, task, p->type);
1454 	if (!inode)
1455 		goto out;
1456 
1457 	ei = PROC_I(inode);
1458 	inode->i_mode = p->mode;
1459 	/*
1460 	 * Yes, it does not scale. And it should not. Don't add
1461 	 * new entries into /proc/<tgid>/ without very good reasons.
1462 	 */
1463 	switch(p->type) {
1464 		case PROC_TGID_TASK:
1465 			inode->i_nlink = 2 + get_tid_list(2, NULL, dir);
1466 			inode->i_op = &proc_task_inode_operations;
1467 			inode->i_fop = &proc_task_operations;
1468 			break;
1469 		case PROC_TID_FD:
1470 		case PROC_TGID_FD:
1471 			inode->i_nlink = 2;
1472 			inode->i_op = &proc_fd_inode_operations;
1473 			inode->i_fop = &proc_fd_operations;
1474 			break;
1475 		case PROC_TID_EXE:
1476 		case PROC_TGID_EXE:
1477 			inode->i_op = &proc_pid_link_inode_operations;
1478 			ei->op.proc_get_link = proc_exe_link;
1479 			break;
1480 		case PROC_TID_CWD:
1481 		case PROC_TGID_CWD:
1482 			inode->i_op = &proc_pid_link_inode_operations;
1483 			ei->op.proc_get_link = proc_cwd_link;
1484 			break;
1485 		case PROC_TID_ROOT:
1486 		case PROC_TGID_ROOT:
1487 			inode->i_op = &proc_pid_link_inode_operations;
1488 			ei->op.proc_get_link = proc_root_link;
1489 			break;
1490 		case PROC_TID_ENVIRON:
1491 		case PROC_TGID_ENVIRON:
1492 			inode->i_fop = &proc_info_file_operations;
1493 			ei->op.proc_read = proc_pid_environ;
1494 			break;
1495 		case PROC_TID_AUXV:
1496 		case PROC_TGID_AUXV:
1497 			inode->i_fop = &proc_info_file_operations;
1498 			ei->op.proc_read = proc_pid_auxv;
1499 			break;
1500 		case PROC_TID_STATUS:
1501 		case PROC_TGID_STATUS:
1502 			inode->i_fop = &proc_info_file_operations;
1503 			ei->op.proc_read = proc_pid_status;
1504 			break;
1505 		case PROC_TID_STAT:
1506 			inode->i_fop = &proc_info_file_operations;
1507 			ei->op.proc_read = proc_tid_stat;
1508 			break;
1509 		case PROC_TGID_STAT:
1510 			inode->i_fop = &proc_info_file_operations;
1511 			ei->op.proc_read = proc_tgid_stat;
1512 			break;
1513 		case PROC_TID_CMDLINE:
1514 		case PROC_TGID_CMDLINE:
1515 			inode->i_fop = &proc_info_file_operations;
1516 			ei->op.proc_read = proc_pid_cmdline;
1517 			break;
1518 		case PROC_TID_STATM:
1519 		case PROC_TGID_STATM:
1520 			inode->i_fop = &proc_info_file_operations;
1521 			ei->op.proc_read = proc_pid_statm;
1522 			break;
1523 		case PROC_TID_MAPS:
1524 		case PROC_TGID_MAPS:
1525 			inode->i_fop = &proc_maps_operations;
1526 			break;
1527 		case PROC_TID_MEM:
1528 		case PROC_TGID_MEM:
1529 			inode->i_op = &proc_mem_inode_operations;
1530 			inode->i_fop = &proc_mem_operations;
1531 			break;
1532 #ifdef CONFIG_SECCOMP
1533 		case PROC_TID_SECCOMP:
1534 		case PROC_TGID_SECCOMP:
1535 			inode->i_fop = &proc_seccomp_operations;
1536 			break;
1537 #endif /* CONFIG_SECCOMP */
1538 		case PROC_TID_MOUNTS:
1539 		case PROC_TGID_MOUNTS:
1540 			inode->i_fop = &proc_mounts_operations;
1541 			break;
1542 #ifdef CONFIG_SECURITY
1543 		case PROC_TID_ATTR:
1544 			inode->i_nlink = 2;
1545 			inode->i_op = &proc_tid_attr_inode_operations;
1546 			inode->i_fop = &proc_tid_attr_operations;
1547 			break;
1548 		case PROC_TGID_ATTR:
1549 			inode->i_nlink = 2;
1550 			inode->i_op = &proc_tgid_attr_inode_operations;
1551 			inode->i_fop = &proc_tgid_attr_operations;
1552 			break;
1553 		case PROC_TID_ATTR_CURRENT:
1554 		case PROC_TGID_ATTR_CURRENT:
1555 		case PROC_TID_ATTR_PREV:
1556 		case PROC_TGID_ATTR_PREV:
1557 		case PROC_TID_ATTR_EXEC:
1558 		case PROC_TGID_ATTR_EXEC:
1559 		case PROC_TID_ATTR_FSCREATE:
1560 		case PROC_TGID_ATTR_FSCREATE:
1561 			inode->i_fop = &proc_pid_attr_operations;
1562 			break;
1563 #endif
1564 #ifdef CONFIG_KALLSYMS
1565 		case PROC_TID_WCHAN:
1566 		case PROC_TGID_WCHAN:
1567 			inode->i_fop = &proc_info_file_operations;
1568 			ei->op.proc_read = proc_pid_wchan;
1569 			break;
1570 #endif
1571 #ifdef CONFIG_SCHEDSTATS
1572 		case PROC_TID_SCHEDSTAT:
1573 		case PROC_TGID_SCHEDSTAT:
1574 			inode->i_fop = &proc_info_file_operations;
1575 			ei->op.proc_read = proc_pid_schedstat;
1576 			break;
1577 #endif
1578 #ifdef CONFIG_CPUSETS
1579 		case PROC_TID_CPUSET:
1580 		case PROC_TGID_CPUSET:
1581 			inode->i_fop = &proc_cpuset_operations;
1582 			break;
1583 #endif
1584 		case PROC_TID_OOM_SCORE:
1585 		case PROC_TGID_OOM_SCORE:
1586 			inode->i_fop = &proc_info_file_operations;
1587 			ei->op.proc_read = proc_oom_score;
1588 			break;
1589 		case PROC_TID_OOM_ADJUST:
1590 		case PROC_TGID_OOM_ADJUST:
1591 			inode->i_fop = &proc_oom_adjust_operations;
1592 			break;
1593 #ifdef CONFIG_AUDITSYSCALL
1594 		case PROC_TID_LOGINUID:
1595 		case PROC_TGID_LOGINUID:
1596 			inode->i_fop = &proc_loginuid_operations;
1597 			break;
1598 #endif
1599 		default:
1600 			printk("procfs: impossible type (%d)",p->type);
1601 			iput(inode);
1602 			return ERR_PTR(-EINVAL);
1603 	}
1604 	dentry->d_op = &pid_dentry_operations;
1605 	d_add(dentry, inode);
1606 	return NULL;
1607 
1608 out:
1609 	return ERR_PTR(error);
1610 }
1611 
1612 static struct dentry *proc_tgid_base_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd){
1613 	return proc_pident_lookup(dir, dentry, tgid_base_stuff);
1614 }
1615 
1616 static struct dentry *proc_tid_base_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd){
1617 	return proc_pident_lookup(dir, dentry, tid_base_stuff);
1618 }
1619 
1620 static struct file_operations proc_tgid_base_operations = {
1621 	.read		= generic_read_dir,
1622 	.readdir	= proc_tgid_base_readdir,
1623 };
1624 
1625 static struct file_operations proc_tid_base_operations = {
1626 	.read		= generic_read_dir,
1627 	.readdir	= proc_tid_base_readdir,
1628 };
1629 
1630 static struct inode_operations proc_tgid_base_inode_operations = {
1631 	.lookup		= proc_tgid_base_lookup,
1632 };
1633 
1634 static struct inode_operations proc_tid_base_inode_operations = {
1635 	.lookup		= proc_tid_base_lookup,
1636 };
1637 
1638 #ifdef CONFIG_SECURITY
1639 static int proc_tgid_attr_readdir(struct file * filp,
1640 			     void * dirent, filldir_t filldir)
1641 {
1642 	return proc_pident_readdir(filp,dirent,filldir,
1643 				   tgid_attr_stuff,ARRAY_SIZE(tgid_attr_stuff));
1644 }
1645 
1646 static int proc_tid_attr_readdir(struct file * filp,
1647 			     void * dirent, filldir_t filldir)
1648 {
1649 	return proc_pident_readdir(filp,dirent,filldir,
1650 				   tid_attr_stuff,ARRAY_SIZE(tid_attr_stuff));
1651 }
1652 
1653 static struct file_operations proc_tgid_attr_operations = {
1654 	.read		= generic_read_dir,
1655 	.readdir	= proc_tgid_attr_readdir,
1656 };
1657 
1658 static struct file_operations proc_tid_attr_operations = {
1659 	.read		= generic_read_dir,
1660 	.readdir	= proc_tid_attr_readdir,
1661 };
1662 
1663 static struct dentry *proc_tgid_attr_lookup(struct inode *dir,
1664 				struct dentry *dentry, struct nameidata *nd)
1665 {
1666 	return proc_pident_lookup(dir, dentry, tgid_attr_stuff);
1667 }
1668 
1669 static struct dentry *proc_tid_attr_lookup(struct inode *dir,
1670 				struct dentry *dentry, struct nameidata *nd)
1671 {
1672 	return proc_pident_lookup(dir, dentry, tid_attr_stuff);
1673 }
1674 
1675 static struct inode_operations proc_tgid_attr_inode_operations = {
1676 	.lookup		= proc_tgid_attr_lookup,
1677 };
1678 
1679 static struct inode_operations proc_tid_attr_inode_operations = {
1680 	.lookup		= proc_tid_attr_lookup,
1681 };
1682 #endif
1683 
1684 /*
1685  * /proc/self:
1686  */
1687 static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
1688 			      int buflen)
1689 {
1690 	char tmp[30];
1691 	sprintf(tmp, "%d", current->tgid);
1692 	return vfs_readlink(dentry,buffer,buflen,tmp);
1693 }
1694 
1695 static int proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)
1696 {
1697 	char tmp[30];
1698 	sprintf(tmp, "%d", current->tgid);
1699 	return vfs_follow_link(nd,tmp);
1700 }
1701 
1702 static struct inode_operations proc_self_inode_operations = {
1703 	.readlink	= proc_self_readlink,
1704 	.follow_link	= proc_self_follow_link,
1705 };
1706 
1707 /**
1708  * proc_pid_unhash -  Unhash /proc/@pid entry from the dcache.
1709  * @p: task that should be flushed.
1710  *
1711  * Drops the /proc/@pid dcache entry from the hash chains.
1712  *
1713  * Dropping /proc/@pid entries and detach_pid must be synchroneous,
1714  * otherwise e.g. /proc/@pid/exe might point to the wrong executable,
1715  * if the pid value is immediately reused. This is enforced by
1716  * - caller must acquire spin_lock(p->proc_lock)
1717  * - must be called before detach_pid()
1718  * - proc_pid_lookup acquires proc_lock, and checks that
1719  *   the target is not dead by looking at the attach count
1720  *   of PIDTYPE_PID.
1721  */
1722 
1723 struct dentry *proc_pid_unhash(struct task_struct *p)
1724 {
1725 	struct dentry *proc_dentry;
1726 
1727 	proc_dentry = p->proc_dentry;
1728 	if (proc_dentry != NULL) {
1729 
1730 		spin_lock(&dcache_lock);
1731 		spin_lock(&proc_dentry->d_lock);
1732 		if (!d_unhashed(proc_dentry)) {
1733 			dget_locked(proc_dentry);
1734 			__d_drop(proc_dentry);
1735 			spin_unlock(&proc_dentry->d_lock);
1736 		} else {
1737 			spin_unlock(&proc_dentry->d_lock);
1738 			proc_dentry = NULL;
1739 		}
1740 		spin_unlock(&dcache_lock);
1741 	}
1742 	return proc_dentry;
1743 }
1744 
1745 /**
1746  * proc_pid_flush - recover memory used by stale /proc/@pid/x entries
1747  * @proc_dentry: directoy to prune.
1748  *
1749  * Shrink the /proc directory that was used by the just killed thread.
1750  */
1751 
1752 void proc_pid_flush(struct dentry *proc_dentry)
1753 {
1754 	might_sleep();
1755 	if(proc_dentry != NULL) {
1756 		shrink_dcache_parent(proc_dentry);
1757 		dput(proc_dentry);
1758 	}
1759 }
1760 
1761 /* SMP-safe */
1762 struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd)
1763 {
1764 	struct task_struct *task;
1765 	struct inode *inode;
1766 	struct proc_inode *ei;
1767 	unsigned tgid;
1768 	int died;
1769 
1770 	if (dentry->d_name.len == 4 && !memcmp(dentry->d_name.name,"self",4)) {
1771 		inode = new_inode(dir->i_sb);
1772 		if (!inode)
1773 			return ERR_PTR(-ENOMEM);
1774 		ei = PROC_I(inode);
1775 		inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
1776 		inode->i_ino = fake_ino(0, PROC_TGID_INO);
1777 		ei->pde = NULL;
1778 		inode->i_mode = S_IFLNK|S_IRWXUGO;
1779 		inode->i_uid = inode->i_gid = 0;
1780 		inode->i_size = 64;
1781 		inode->i_op = &proc_self_inode_operations;
1782 		d_add(dentry, inode);
1783 		return NULL;
1784 	}
1785 	tgid = name_to_int(dentry);
1786 	if (tgid == ~0U)
1787 		goto out;
1788 
1789 	read_lock(&tasklist_lock);
1790 	task = find_task_by_pid(tgid);
1791 	if (task)
1792 		get_task_struct(task);
1793 	read_unlock(&tasklist_lock);
1794 	if (!task)
1795 		goto out;
1796 
1797 	inode = proc_pid_make_inode(dir->i_sb, task, PROC_TGID_INO);
1798 
1799 
1800 	if (!inode) {
1801 		put_task_struct(task);
1802 		goto out;
1803 	}
1804 	inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
1805 	inode->i_op = &proc_tgid_base_inode_operations;
1806 	inode->i_fop = &proc_tgid_base_operations;
1807 	inode->i_flags|=S_IMMUTABLE;
1808 #ifdef CONFIG_SECURITY
1809 	inode->i_nlink = 5;
1810 #else
1811 	inode->i_nlink = 4;
1812 #endif
1813 
1814 	dentry->d_op = &pid_base_dentry_operations;
1815 
1816 	died = 0;
1817 	d_add(dentry, inode);
1818 	spin_lock(&task->proc_lock);
1819 	task->proc_dentry = dentry;
1820 	if (!pid_alive(task)) {
1821 		dentry = proc_pid_unhash(task);
1822 		died = 1;
1823 	}
1824 	spin_unlock(&task->proc_lock);
1825 
1826 	put_task_struct(task);
1827 	if (died) {
1828 		proc_pid_flush(dentry);
1829 		goto out;
1830 	}
1831 	return NULL;
1832 out:
1833 	return ERR_PTR(-ENOENT);
1834 }
1835 
1836 /* SMP-safe */
1837 static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd)
1838 {
1839 	struct task_struct *task;
1840 	struct task_struct *leader = proc_task(dir);
1841 	struct inode *inode;
1842 	unsigned tid;
1843 
1844 	tid = name_to_int(dentry);
1845 	if (tid == ~0U)
1846 		goto out;
1847 
1848 	read_lock(&tasklist_lock);
1849 	task = find_task_by_pid(tid);
1850 	if (task)
1851 		get_task_struct(task);
1852 	read_unlock(&tasklist_lock);
1853 	if (!task)
1854 		goto out;
1855 	if (leader->tgid != task->tgid)
1856 		goto out_drop_task;
1857 
1858 	inode = proc_pid_make_inode(dir->i_sb, task, PROC_TID_INO);
1859 
1860 
1861 	if (!inode)
1862 		goto out_drop_task;
1863 	inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
1864 	inode->i_op = &proc_tid_base_inode_operations;
1865 	inode->i_fop = &proc_tid_base_operations;
1866 	inode->i_flags|=S_IMMUTABLE;
1867 #ifdef CONFIG_SECURITY
1868 	inode->i_nlink = 4;
1869 #else
1870 	inode->i_nlink = 3;
1871 #endif
1872 
1873 	dentry->d_op = &pid_base_dentry_operations;
1874 
1875 	d_add(dentry, inode);
1876 
1877 	put_task_struct(task);
1878 	return NULL;
1879 out_drop_task:
1880 	put_task_struct(task);
1881 out:
1882 	return ERR_PTR(-ENOENT);
1883 }
1884 
1885 #define PROC_NUMBUF 10
1886 #define PROC_MAXPIDS 20
1887 
1888 /*
1889  * Get a few tgid's to return for filldir - we need to hold the
1890  * tasklist lock while doing this, and we must release it before
1891  * we actually do the filldir itself, so we use a temp buffer..
1892  */
1893 static int get_tgid_list(int index, unsigned long version, unsigned int *tgids)
1894 {
1895 	struct task_struct *p;
1896 	int nr_tgids = 0;
1897 
1898 	index--;
1899 	read_lock(&tasklist_lock);
1900 	p = NULL;
1901 	if (version) {
1902 		p = find_task_by_pid(version);
1903 		if (p && !thread_group_leader(p))
1904 			p = NULL;
1905 	}
1906 
1907 	if (p)
1908 		index = 0;
1909 	else
1910 		p = next_task(&init_task);
1911 
1912 	for ( ; p != &init_task; p = next_task(p)) {
1913 		int tgid = p->pid;
1914 		if (!pid_alive(p))
1915 			continue;
1916 		if (--index >= 0)
1917 			continue;
1918 		tgids[nr_tgids] = tgid;
1919 		nr_tgids++;
1920 		if (nr_tgids >= PROC_MAXPIDS)
1921 			break;
1922 	}
1923 	read_unlock(&tasklist_lock);
1924 	return nr_tgids;
1925 }
1926 
1927 /*
1928  * Get a few tid's to return for filldir - we need to hold the
1929  * tasklist lock while doing this, and we must release it before
1930  * we actually do the filldir itself, so we use a temp buffer..
1931  */
1932 static int get_tid_list(int index, unsigned int *tids, struct inode *dir)
1933 {
1934 	struct task_struct *leader_task = proc_task(dir);
1935 	struct task_struct *task = leader_task;
1936 	int nr_tids = 0;
1937 
1938 	index -= 2;
1939 	read_lock(&tasklist_lock);
1940 	/*
1941 	 * The starting point task (leader_task) might be an already
1942 	 * unlinked task, which cannot be used to access the task-list
1943 	 * via next_thread().
1944 	 */
1945 	if (pid_alive(task)) do {
1946 		int tid = task->pid;
1947 
1948 		if (--index >= 0)
1949 			continue;
1950 		if (tids != NULL)
1951 			tids[nr_tids] = tid;
1952 		nr_tids++;
1953 		if (nr_tids >= PROC_MAXPIDS)
1954 			break;
1955 	} while ((task = next_thread(task)) != leader_task);
1956 	read_unlock(&tasklist_lock);
1957 	return nr_tids;
1958 }
1959 
1960 /* for the /proc/ directory itself, after non-process stuff has been done */
1961 int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
1962 {
1963 	unsigned int tgid_array[PROC_MAXPIDS];
1964 	char buf[PROC_NUMBUF];
1965 	unsigned int nr = filp->f_pos - FIRST_PROCESS_ENTRY;
1966 	unsigned int nr_tgids, i;
1967 	int next_tgid;
1968 
1969 	if (!nr) {
1970 		ino_t ino = fake_ino(0,PROC_TGID_INO);
1971 		if (filldir(dirent, "self", 4, filp->f_pos, ino, DT_LNK) < 0)
1972 			return 0;
1973 		filp->f_pos++;
1974 		nr++;
1975 	}
1976 
1977 	/* f_version caches the tgid value that the last readdir call couldn't
1978 	 * return. lseek aka telldir automagically resets f_version to 0.
1979 	 */
1980 	next_tgid = filp->f_version;
1981 	filp->f_version = 0;
1982 	for (;;) {
1983 		nr_tgids = get_tgid_list(nr, next_tgid, tgid_array);
1984 		if (!nr_tgids) {
1985 			/* no more entries ! */
1986 			break;
1987 		}
1988 		next_tgid = 0;
1989 
1990 		/* do not use the last found pid, reserve it for next_tgid */
1991 		if (nr_tgids == PROC_MAXPIDS) {
1992 			nr_tgids--;
1993 			next_tgid = tgid_array[nr_tgids];
1994 		}
1995 
1996 		for (i=0;i<nr_tgids;i++) {
1997 			int tgid = tgid_array[i];
1998 			ino_t ino = fake_ino(tgid,PROC_TGID_INO);
1999 			unsigned long j = PROC_NUMBUF;
2000 
2001 			do
2002 				buf[--j] = '0' + (tgid % 10);
2003 			while ((tgid /= 10) != 0);
2004 
2005 			if (filldir(dirent, buf+j, PROC_NUMBUF-j, filp->f_pos, ino, DT_DIR) < 0) {
2006 				/* returning this tgid failed, save it as the first
2007 				 * pid for the next readir call */
2008 				filp->f_version = tgid_array[i];
2009 				goto out;
2010 			}
2011 			filp->f_pos++;
2012 			nr++;
2013 		}
2014 	}
2015 out:
2016 	return 0;
2017 }
2018 
2019 /* for the /proc/TGID/task/ directories */
2020 static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldir)
2021 {
2022 	unsigned int tid_array[PROC_MAXPIDS];
2023 	char buf[PROC_NUMBUF];
2024 	unsigned int nr_tids, i;
2025 	struct dentry *dentry = filp->f_dentry;
2026 	struct inode *inode = dentry->d_inode;
2027 	int retval = -ENOENT;
2028 	ino_t ino;
2029 	unsigned long pos = filp->f_pos;  /* avoiding "long long" filp->f_pos */
2030 
2031 	if (!pid_alive(proc_task(inode)))
2032 		goto out;
2033 	retval = 0;
2034 
2035 	switch (pos) {
2036 	case 0:
2037 		ino = inode->i_ino;
2038 		if (filldir(dirent, ".", 1, pos, ino, DT_DIR) < 0)
2039 			goto out;
2040 		pos++;
2041 		/* fall through */
2042 	case 1:
2043 		ino = parent_ino(dentry);
2044 		if (filldir(dirent, "..", 2, pos, ino, DT_DIR) < 0)
2045 			goto out;
2046 		pos++;
2047 		/* fall through */
2048 	}
2049 
2050 	nr_tids = get_tid_list(pos, tid_array, inode);
2051 	inode->i_nlink = pos + nr_tids;
2052 
2053 	for (i = 0; i < nr_tids; i++) {
2054 		unsigned long j = PROC_NUMBUF;
2055 		int tid = tid_array[i];
2056 
2057 		ino = fake_ino(tid,PROC_TID_INO);
2058 
2059 		do
2060 			buf[--j] = '0' + (tid % 10);
2061 		while ((tid /= 10) != 0);
2062 
2063 		if (filldir(dirent, buf+j, PROC_NUMBUF-j, pos, ino, DT_DIR) < 0)
2064 			break;
2065 		pos++;
2066 	}
2067 out:
2068 	filp->f_pos = pos;
2069 	return retval;
2070 }
2071