1// SPDX-License-Identifier: GPL-2.0
  2#include <linux/sched/signal.h>
  3#include <linux/errno.h>
  4#include <linux/dcache.h>
  5#include <linux/path.h>
  6#include <linux/fdtable.h>
  7#include <linux/namei.h>
  8#include <linux/pid.h>
  9#include <linux/ptrace.h>
 10#include <linux/bitmap.h>
 11#include <linux/security.h>
 12#include <linux/file.h>
 13#include <linux/seq_file.h>
 14#include <linux/fs.h>
 15
 16#include <linux/proc_fs.h>
 17
 18#include "../mount.h"
 19#include "internal.h"
 20#include "fd.h"
 21
 22static int seq_show(struct seq_file *m, void *v)
 23{
 24	struct files_struct *files = NULL;
 25	int f_flags = 0, ret = -ENOENT;
 26	struct file *file = NULL;
 27	struct task_struct *task;
 28
 29	task = get_proc_task(m->private);
 30	if (!task)
 31		return -ENOENT;
 32
 33	task_lock(task);
 34	files = task->files;
 
 35	if (files) {
 36		unsigned int fd = proc_fd(m->private);
 37
 38		spin_lock(&files->file_lock);
 39		file = files_lookup_fd_locked(files, fd);
 40		if (file) {
 41			struct fdtable *fdt = files_fdtable(files);
 42
 43			f_flags = file->f_flags;
 44			if (close_on_exec(fd, fdt))
 45				f_flags |= O_CLOEXEC;
 46
 47			get_file(file);
 48			ret = 0;
 49		}
 50		spin_unlock(&files->file_lock);
 
 51	}
 52	task_unlock(task);
 53	put_task_struct(task);
 54
 55	if (ret)
 56		return ret;
 57
 58	seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\nino:\t%lu\n",
 59		   (long long)file->f_pos, f_flags,
 60		   real_mount(file->f_path.mnt)->mnt_id,
 61		   file_inode(file)->i_ino);
 62
 63	/* show_fd_locks() never deferences files so a stale value is safe */
 64	show_fd_locks(m, file, files);
 65	if (seq_has_overflowed(m))
 66		goto out;
 67
 68	if (file->f_op->show_fdinfo)
 69		file->f_op->show_fdinfo(m, file);
 70
 71out:
 72	fput(file);
 73	return 0;
 74}
 75
 76static int proc_fdinfo_access_allowed(struct inode *inode)
 77{
 78	bool allowed = false;
 79	struct task_struct *task = get_proc_task(inode);
 80
 81	if (!task)
 82		return -ESRCH;
 83
 84	allowed = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
 85	put_task_struct(task);
 86
 87	if (!allowed)
 88		return -EACCES;
 89
 90	return 0;
 91}
 92
 93static int seq_fdinfo_open(struct inode *inode, struct file *file)
 94{
 95	int ret = proc_fdinfo_access_allowed(inode);
 96
 97	if (ret)
 98		return ret;
 99
100	return single_open(file, seq_show, inode);
101}
102
103static const struct file_operations proc_fdinfo_file_operations = {
104	.open		= seq_fdinfo_open,
105	.read		= seq_read,
106	.llseek		= seq_lseek,
107	.release	= single_release,
108};
109
110static bool tid_fd_mode(struct task_struct *task, unsigned fd, fmode_t *mode)
111{
112	struct file *file;
113
114	rcu_read_lock();
115	file = task_lookup_fd_rcu(task, fd);
116	if (file)
117		*mode = file->f_mode;
118	rcu_read_unlock();
119	return !!file;
120}
121
122static void tid_fd_update_inode(struct task_struct *task, struct inode *inode,
123				fmode_t f_mode)
124{
125	task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
126
127	if (S_ISLNK(inode->i_mode)) {
128		unsigned i_mode = S_IFLNK;
129		if (f_mode & FMODE_READ)
130			i_mode |= S_IRUSR | S_IXUSR;
131		if (f_mode & FMODE_WRITE)
132			i_mode |= S_IWUSR | S_IXUSR;
133		inode->i_mode = i_mode;
134	}
135	security_task_to_inode(task, inode);
136}
137
138static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
139{
 
140	struct task_struct *task;
141	struct inode *inode;
142	unsigned int fd;
143
144	if (flags & LOOKUP_RCU)
145		return -ECHILD;
146
147	inode = d_inode(dentry);
148	task = get_proc_task(inode);
149	fd = proc_fd(inode);
150
151	if (task) {
152		fmode_t f_mode;
153		if (tid_fd_mode(task, fd, &f_mode)) {
154			tid_fd_update_inode(task, inode, f_mode);
155			put_task_struct(task);
156			return 1;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
157		}
158		put_task_struct(task);
159	}
160	return 0;
161}
162
163static const struct dentry_operations tid_fd_dentry_operations = {
164	.d_revalidate	= tid_fd_revalidate,
165	.d_delete	= pid_delete_dentry,
166};
167
168static int proc_fd_link(struct dentry *dentry, struct path *path)
169{
 
170	struct task_struct *task;
171	int ret = -ENOENT;
172
173	task = get_proc_task(d_inode(dentry));
174	if (task) {
 
 
 
 
 
175		unsigned int fd = proc_fd(d_inode(dentry));
176		struct file *fd_file;
177
178		fd_file = fget_task(task, fd);
 
179		if (fd_file) {
180			*path = fd_file->f_path;
181			path_get(&fd_file->f_path);
182			ret = 0;
183			fput(fd_file);
184		}
185		put_task_struct(task);
 
186	}
187
188	return ret;
189}
190
191struct fd_data {
192	fmode_t mode;
193	unsigned fd;
194};
195
196static struct dentry *proc_fd_instantiate(struct dentry *dentry,
197	struct task_struct *task, const void *ptr)
198{
199	const struct fd_data *data = ptr;
200	struct proc_inode *ei;
201	struct inode *inode;
202
203	inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK);
204	if (!inode)
205		return ERR_PTR(-ENOENT);
206
207	ei = PROC_I(inode);
208	ei->fd = data->fd;
209
210	inode->i_op = &proc_pid_link_inode_operations;
211	inode->i_size = 64;
212
213	ei->op.proc_get_link = proc_fd_link;
214	tid_fd_update_inode(task, inode, data->mode);
215
216	d_set_d_op(dentry, &tid_fd_dentry_operations);
217	return d_splice_alias(inode, dentry);
 
 
 
 
 
 
218}
219
220static struct dentry *proc_lookupfd_common(struct inode *dir,
221					   struct dentry *dentry,
222					   instantiate_t instantiate)
223{
224	struct task_struct *task = get_proc_task(dir);
225	struct fd_data data = {.fd = name_to_int(&dentry->d_name)};
226	struct dentry *result = ERR_PTR(-ENOENT);
227
228	if (!task)
229		goto out_no_task;
230	if (data.fd == ~0U)
231		goto out;
232	if (!tid_fd_mode(task, data.fd, &data.mode))
233		goto out;
234
235	result = instantiate(dentry, task, &data);
236out:
237	put_task_struct(task);
238out_no_task:
239	return result;
240}
241
242static int proc_readfd_common(struct file *file, struct dir_context *ctx,
243			      instantiate_t instantiate)
244{
245	struct task_struct *p = get_proc_task(file_inode(file));
 
246	unsigned int fd;
247
248	if (!p)
249		return -ENOENT;
250
251	if (!dir_emit_dots(file, ctx))
252		goto out;
 
 
 
253
254	rcu_read_lock();
255	for (fd = ctx->pos - 2;; fd++) {
256		struct file *f;
257		struct fd_data data;
258		char name[10 + 1];
259		unsigned int len;
260
261		f = task_lookup_next_fd_rcu(p, &fd);
262		ctx->pos = fd + 2LL;
263		if (!f)
264			break;
265		data.mode = f->f_mode;
266		rcu_read_unlock();
267		data.fd = fd;
268
269		len = snprintf(name, sizeof(name), "%u", fd);
270		if (!proc_fill_cache(file, ctx,
271				     name, len, instantiate, p,
272				     &data))
273			goto out;
274		cond_resched();
275		rcu_read_lock();
276	}
277	rcu_read_unlock();
 
 
278out:
279	put_task_struct(p);
280	return 0;
281}
282
283static int proc_readfd_count(struct inode *inode, loff_t *count)
284{
285	struct task_struct *p = get_proc_task(inode);
286	struct fdtable *fdt;
287
288	if (!p)
289		return -ENOENT;
290
291	task_lock(p);
292	if (p->files) {
293		rcu_read_lock();
294
295		fdt = files_fdtable(p->files);
296		*count = bitmap_weight(fdt->open_fds, fdt->max_fds);
297
298		rcu_read_unlock();
299	}
300	task_unlock(p);
301
302	put_task_struct(p);
303
304	return 0;
305}
306
307static int proc_readfd(struct file *file, struct dir_context *ctx)
308{
309	return proc_readfd_common(file, ctx, proc_fd_instantiate);
310}
311
312const struct file_operations proc_fd_operations = {
313	.read		= generic_read_dir,
314	.iterate_shared	= proc_readfd,
315	.llseek		= generic_file_llseek,
316};
317
318static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
319				    unsigned int flags)
320{
321	return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
322}
323
324/*
325 * /proc/pid/fd needs a special permission handler so that a process can still
326 * access /proc/self/fd after it has executed a setuid().
327 */
328int proc_fd_permission(struct user_namespace *mnt_userns,
329		       struct inode *inode, int mask)
330{
331	struct task_struct *p;
332	int rv;
333
334	rv = generic_permission(&init_user_ns, inode, mask);
335	if (rv == 0)
336		return rv;
337
338	rcu_read_lock();
339	p = pid_task(proc_pid(inode), PIDTYPE_PID);
340	if (p && same_thread_group(p, current))
341		rv = 0;
342	rcu_read_unlock();
343
344	return rv;
345}
346
347static int proc_fd_getattr(struct user_namespace *mnt_userns,
348			const struct path *path, struct kstat *stat,
349			u32 request_mask, unsigned int query_flags)
350{
351	struct inode *inode = d_inode(path->dentry);
352	int rv = 0;
353
354	generic_fillattr(&init_user_ns, inode, stat);
355
356	/* If it's a directory, put the number of open fds there */
357	if (S_ISDIR(inode->i_mode)) {
358		rv = proc_readfd_count(inode, &stat->size);
359		if (rv < 0)
360			return rv;
361	}
362
363	return rv;
364}
365
366const struct inode_operations proc_fd_inode_operations = {
367	.lookup		= proc_lookupfd,
368	.permission	= proc_fd_permission,
369	.getattr	= proc_fd_getattr,
370	.setattr	= proc_setattr,
371};
372
373static struct dentry *proc_fdinfo_instantiate(struct dentry *dentry,
374	struct task_struct *task, const void *ptr)
 
375{
376	const struct fd_data *data = ptr;
377	struct proc_inode *ei;
378	struct inode *inode;
379
380	inode = proc_pid_make_inode(dentry->d_sb, task, S_IFREG | S_IRUGO);
381	if (!inode)
382		return ERR_PTR(-ENOENT);
383
384	ei = PROC_I(inode);
385	ei->fd = data->fd;
386
387	inode->i_fop = &proc_fdinfo_file_operations;
388	tid_fd_update_inode(task, inode, 0);
389
390	d_set_d_op(dentry, &tid_fd_dentry_operations);
391	return d_splice_alias(inode, dentry);
 
 
 
 
 
 
392}
393
394static struct dentry *
395proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags)
396{
397	return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
398}
399
400static int proc_readfdinfo(struct file *file, struct dir_context *ctx)
401{
402	return proc_readfd_common(file, ctx,
403				  proc_fdinfo_instantiate);
404}
405
406static int proc_open_fdinfo(struct inode *inode, struct file *file)
407{
408	int ret = proc_fdinfo_access_allowed(inode);
409
410	if (ret)
411		return ret;
412
413	return 0;
414}
415
416const struct inode_operations proc_fdinfo_inode_operations = {
417	.lookup		= proc_lookupfdinfo,
418	.setattr	= proc_setattr,
419};
420
421const struct file_operations proc_fdinfo_operations = {
422	.open		= proc_open_fdinfo,
423	.read		= generic_read_dir,
424	.iterate_shared	= proc_readfdinfo,
425	.llseek		= generic_file_llseek,
426};

  1// SPDX-License-Identifier: GPL-2.0
  2#include <linux/sched/signal.h>
  3#include <linux/errno.h>
  4#include <linux/dcache.h>
  5#include <linux/path.h>
  6#include <linux/fdtable.h>
  7#include <linux/namei.h>
  8#include <linux/pid.h>
 
 
  9#include <linux/security.h>
 10#include <linux/file.h>
 11#include <linux/seq_file.h>
 12#include <linux/fs.h>
 13
 14#include <linux/proc_fs.h>
 15
 16#include "../mount.h"
 17#include "internal.h"
 18#include "fd.h"
 19
 20static int seq_show(struct seq_file *m, void *v)
 21{
 22	struct files_struct *files = NULL;
 23	int f_flags = 0, ret = -ENOENT;
 24	struct file *file = NULL;
 25	struct task_struct *task;
 26
 27	task = get_proc_task(m->private);
 28	if (!task)
 29		return -ENOENT;
 30
 31	files = get_files_struct(task);
 32	put_task_struct(task);
 33
 34	if (files) {
 35		unsigned int fd = proc_fd(m->private);
 36
 37		spin_lock(&files->file_lock);
 38		file = fcheck_files(files, fd);
 39		if (file) {
 40			struct fdtable *fdt = files_fdtable(files);
 41
 42			f_flags = file->f_flags;
 43			if (close_on_exec(fd, fdt))
 44				f_flags |= O_CLOEXEC;
 45
 46			get_file(file);
 47			ret = 0;
 48		}
 49		spin_unlock(&files->file_lock);
 50		put_files_struct(files);
 51	}
 
 
 52
 53	if (ret)
 54		return ret;
 55
 56	seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\n",
 57		   (long long)file->f_pos, f_flags,
 58		   real_mount(file->f_path.mnt)->mnt_id);
 
 59
 
 60	show_fd_locks(m, file, files);
 61	if (seq_has_overflowed(m))
 62		goto out;
 63
 64	if (file->f_op->show_fdinfo)
 65		file->f_op->show_fdinfo(m, file);
 66
 67out:
 68	fput(file);
 69	return 0;
 70}
 71
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 72static int seq_fdinfo_open(struct inode *inode, struct file *file)
 73{
 
 
 
 
 
 74	return single_open(file, seq_show, inode);
 75}
 76
 77static const struct file_operations proc_fdinfo_file_operations = {
 78	.open		= seq_fdinfo_open,
 79	.read		= seq_read,
 80	.llseek		= seq_lseek,
 81	.release	= single_release,
 82};
 83
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 84static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
 85{
 86	struct files_struct *files;
 87	struct task_struct *task;
 88	struct inode *inode;
 89	unsigned int fd;
 90
 91	if (flags & LOOKUP_RCU)
 92		return -ECHILD;
 93
 94	inode = d_inode(dentry);
 95	task = get_proc_task(inode);
 96	fd = proc_fd(inode);
 97
 98	if (task) {
 99		files = get_files_struct(task);
100		if (files) {
101			struct file *file;
102
103			rcu_read_lock();
104			file = fcheck_files(files, fd);
105			if (file) {
106				unsigned f_mode = file->f_mode;
107
108				rcu_read_unlock();
109				put_files_struct(files);
110
111				task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
112
113				if (S_ISLNK(inode->i_mode)) {
114					unsigned i_mode = S_IFLNK;
115					if (f_mode & FMODE_READ)
116						i_mode |= S_IRUSR | S_IXUSR;
117					if (f_mode & FMODE_WRITE)
118						i_mode |= S_IWUSR | S_IXUSR;
119					inode->i_mode = i_mode;
120				}
121
122				security_task_to_inode(task, inode);
123				put_task_struct(task);
124				return 1;
125			}
126			rcu_read_unlock();
127			put_files_struct(files);
128		}
129		put_task_struct(task);
130	}
131	return 0;
132}
133
134static const struct dentry_operations tid_fd_dentry_operations = {
135	.d_revalidate	= tid_fd_revalidate,
136	.d_delete	= pid_delete_dentry,
137};
138
139static int proc_fd_link(struct dentry *dentry, struct path *path)
140{
141	struct files_struct *files = NULL;
142	struct task_struct *task;
143	int ret = -ENOENT;
144
145	task = get_proc_task(d_inode(dentry));
146	if (task) {
147		files = get_files_struct(task);
148		put_task_struct(task);
149	}
150
151	if (files) {
152		unsigned int fd = proc_fd(d_inode(dentry));
153		struct file *fd_file;
154
155		spin_lock(&files->file_lock);
156		fd_file = fcheck_files(files, fd);
157		if (fd_file) {
158			*path = fd_file->f_path;
159			path_get(&fd_file->f_path);
160			ret = 0;
 
161		}
162		spin_unlock(&files->file_lock);
163		put_files_struct(files);
164	}
165
166	return ret;
167}
168
169static int
170proc_fd_instantiate(struct inode *dir, struct dentry *dentry,
171		    struct task_struct *task, const void *ptr)
 
 
 
 
172{
173	unsigned fd = (unsigned long)ptr;
174	struct proc_inode *ei;
175	struct inode *inode;
176
177	inode = proc_pid_make_inode(dir->i_sb, task, S_IFLNK);
178	if (!inode)
179		goto out;
180
181	ei = PROC_I(inode);
182	ei->fd = fd;
183
184	inode->i_op = &proc_pid_link_inode_operations;
185	inode->i_size = 64;
186
187	ei->op.proc_get_link = proc_fd_link;
 
188
189	d_set_d_op(dentry, &tid_fd_dentry_operations);
190	d_add(dentry, inode);
191
192	/* Close the race of the process dying before we return the dentry */
193	if (tid_fd_revalidate(dentry, 0))
194		return 0;
195 out:
196	return -ENOENT;
197}
198
199static struct dentry *proc_lookupfd_common(struct inode *dir,
200					   struct dentry *dentry,
201					   instantiate_t instantiate)
202{
203	struct task_struct *task = get_proc_task(dir);
204	int result = -ENOENT;
205	unsigned fd = name_to_int(&dentry->d_name);
206
207	if (!task)
208		goto out_no_task;
209	if (fd == ~0U)
 
 
210		goto out;
211
212	result = instantiate(dir, dentry, task, (void *)(unsigned long)fd);
213out:
214	put_task_struct(task);
215out_no_task:
216	return ERR_PTR(result);
217}
218
219static int proc_readfd_common(struct file *file, struct dir_context *ctx,
220			      instantiate_t instantiate)
221{
222	struct task_struct *p = get_proc_task(file_inode(file));
223	struct files_struct *files;
224	unsigned int fd;
225
226	if (!p)
227		return -ENOENT;
228
229	if (!dir_emit_dots(file, ctx))
230		goto out;
231	files = get_files_struct(p);
232	if (!files)
233		goto out;
234
235	rcu_read_lock();
236	for (fd = ctx->pos - 2;
237	     fd < files_fdtable(files)->max_fds;
238	     fd++, ctx->pos++) {
239		char name[10 + 1];
240		int len;
241
242		if (!fcheck_files(files, fd))
243			continue;
 
 
 
244		rcu_read_unlock();
 
245
246		len = snprintf(name, sizeof(name), "%u", fd);
247		if (!proc_fill_cache(file, ctx,
248				     name, len, instantiate, p,
249				     (void *)(unsigned long)fd))
250			goto out_fd_loop;
251		cond_resched();
252		rcu_read_lock();
253	}
254	rcu_read_unlock();
255out_fd_loop:
256	put_files_struct(files);
257out:
258	put_task_struct(p);
259	return 0;
260}
261
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
262static int proc_readfd(struct file *file, struct dir_context *ctx)
263{
264	return proc_readfd_common(file, ctx, proc_fd_instantiate);
265}
266
267const struct file_operations proc_fd_operations = {
268	.read		= generic_read_dir,
269	.iterate_shared	= proc_readfd,
270	.llseek		= generic_file_llseek,
271};
272
273static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
274				    unsigned int flags)
275{
276	return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
277}
278
279/*
280 * /proc/pid/fd needs a special permission handler so that a process can still
281 * access /proc/self/fd after it has executed a setuid().
282 */
283int proc_fd_permission(struct inode *inode, int mask)
 
284{
285	struct task_struct *p;
286	int rv;
287
288	rv = generic_permission(inode, mask);
289	if (rv == 0)
290		return rv;
291
292	rcu_read_lock();
293	p = pid_task(proc_pid(inode), PIDTYPE_PID);
294	if (p && same_thread_group(p, current))
295		rv = 0;
296	rcu_read_unlock();
297
298	return rv;
299}
300
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
301const struct inode_operations proc_fd_inode_operations = {
302	.lookup		= proc_lookupfd,
303	.permission	= proc_fd_permission,
 
304	.setattr	= proc_setattr,
305};
306
307static int
308proc_fdinfo_instantiate(struct inode *dir, struct dentry *dentry,
309			struct task_struct *task, const void *ptr)
310{
311	unsigned fd = (unsigned long)ptr;
312	struct proc_inode *ei;
313	struct inode *inode;
314
315	inode = proc_pid_make_inode(dir->i_sb, task, S_IFREG | S_IRUSR);
316	if (!inode)
317		goto out;
318
319	ei = PROC_I(inode);
320	ei->fd = fd;
321
322	inode->i_fop = &proc_fdinfo_file_operations;
 
323
324	d_set_d_op(dentry, &tid_fd_dentry_operations);
325	d_add(dentry, inode);
326
327	/* Close the race of the process dying before we return the dentry */
328	if (tid_fd_revalidate(dentry, 0))
329		return 0;
330 out:
331	return -ENOENT;
332}
333
334static struct dentry *
335proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags)
336{
337	return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
338}
339
340static int proc_readfdinfo(struct file *file, struct dir_context *ctx)
341{
342	return proc_readfd_common(file, ctx,
343				  proc_fdinfo_instantiate);
344}
345
 
 
 
 
 
 
 
 
 
 
346const struct inode_operations proc_fdinfo_inode_operations = {
347	.lookup		= proc_lookupfdinfo,
348	.setattr	= proc_setattr,
349};
350
351const struct file_operations proc_fdinfo_operations = {
 
352	.read		= generic_read_dir,
353	.iterate_shared	= proc_readfdinfo,
354	.llseek		= generic_file_llseek,
355};