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#include <linux/filelock.h>
 16
 17#include <linux/proc_fs.h>
 18
 19#include "../mount.h"
 20#include "internal.h"
 21#include "fd.h"
 22
 23static int seq_show(struct seq_file *m, void *v)
 24{
 25	struct files_struct *files = NULL;
 26	int f_flags = 0, ret = -ENOENT;
 27	struct file *file = NULL;
 28	struct task_struct *task;
 29
 30	task = get_proc_task(m->private);
 31	if (!task)
 32		return -ENOENT;
 33
 34	task_lock(task);
 35	files = task->files;
 
 36	if (files) {
 37		unsigned int fd = proc_fd(m->private);
 38
 39		spin_lock(&files->file_lock);
 40		file = files_lookup_fd_locked(files, fd);
 41		if (file) {
 42			struct fdtable *fdt = files_fdtable(files);
 43
 44			f_flags = file->f_flags;
 45			if (close_on_exec(fd, fdt))
 46				f_flags |= O_CLOEXEC;
 47
 48			get_file(file);
 49			ret = 0;
 50		}
 51		spin_unlock(&files->file_lock);
 
 52	}
 53	task_unlock(task);
 54	put_task_struct(task);
 55
 56	if (ret)
 57		return ret;
 58
 59	seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\nino:\t%lu\n",
 60		   (long long)file->f_pos, f_flags,
 61		   real_mount(file->f_path.mnt)->mnt_id,
 62		   file_inode(file)->i_ino);
 63
 64	/* show_fd_locks() never deferences files so a stale value is safe */
 65	show_fd_locks(m, file, files);
 66	if (seq_has_overflowed(m))
 67		goto out;
 68
 69	if (file->f_op->show_fdinfo)
 70		file->f_op->show_fdinfo(m, file);
 71
 72out:
 73	fput(file);
 74	return 0;
 75}
 76
 77static int proc_fdinfo_access_allowed(struct inode *inode)
 78{
 79	bool allowed = false;
 80	struct task_struct *task = get_proc_task(inode);
 81
 82	if (!task)
 83		return -ESRCH;
 84
 85	allowed = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
 86	put_task_struct(task);
 87
 88	if (!allowed)
 89		return -EACCES;
 90
 91	return 0;
 92}
 93
 94static int seq_fdinfo_open(struct inode *inode, struct file *file)
 95{
 96	int ret = proc_fdinfo_access_allowed(inode);
 97
 98	if (ret)
 99		return ret;
100
101	return single_open(file, seq_show, inode);
102}
103
104static const struct file_operations proc_fdinfo_file_operations = {
105	.open		= seq_fdinfo_open,
106	.read		= seq_read,
107	.llseek		= seq_lseek,
108	.release	= single_release,
109};
110
111static bool tid_fd_mode(struct task_struct *task, unsigned fd, fmode_t *mode)
112{
113	struct file *file;
114
115	rcu_read_lock();
116	file = task_lookup_fdget_rcu(task, fd);
117	rcu_read_unlock();
118	if (file) {
119		*mode = file->f_mode;
120		fput(file);
121	}
122	return !!file;
123}
124
125static void tid_fd_update_inode(struct task_struct *task, struct inode *inode,
126				fmode_t f_mode)
127{
128	task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
129
130	if (S_ISLNK(inode->i_mode)) {
131		unsigned i_mode = S_IFLNK;
132		if (f_mode & FMODE_READ)
133			i_mode |= S_IRUSR | S_IXUSR;
134		if (f_mode & FMODE_WRITE)
135			i_mode |= S_IWUSR | S_IXUSR;
136		inode->i_mode = i_mode;
137	}
138	security_task_to_inode(task, inode);
139}
140
141static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
142{
 
143	struct task_struct *task;
144	struct inode *inode;
145	unsigned int fd;
146
147	if (flags & LOOKUP_RCU)
148		return -ECHILD;
149
150	inode = d_inode(dentry);
151	task = get_proc_task(inode);
152	fd = proc_fd(inode);
153
154	if (task) {
155		fmode_t f_mode;
156		if (tid_fd_mode(task, fd, &f_mode)) {
157			tid_fd_update_inode(task, inode, f_mode);
158			put_task_struct(task);
159			return 1;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
160		}
161		put_task_struct(task);
162	}
163	return 0;
164}
165
166static const struct dentry_operations tid_fd_dentry_operations = {
167	.d_revalidate	= tid_fd_revalidate,
168	.d_delete	= pid_delete_dentry,
169};
170
171static int proc_fd_link(struct dentry *dentry, struct path *path)
172{
 
173	struct task_struct *task;
174	int ret = -ENOENT;
175
176	task = get_proc_task(d_inode(dentry));
177	if (task) {
 
 
 
 
 
178		unsigned int fd = proc_fd(d_inode(dentry));
179		struct file *fd_file;
180
181		fd_file = fget_task(task, fd);
 
182		if (fd_file) {
183			*path = fd_file->f_path;
184			path_get(&fd_file->f_path);
185			ret = 0;
186			fput(fd_file);
187		}
188		put_task_struct(task);
 
189	}
190
191	return ret;
192}
193
194struct fd_data {
195	fmode_t mode;
196	unsigned fd;
197};
198
199static struct dentry *proc_fd_instantiate(struct dentry *dentry,
200	struct task_struct *task, const void *ptr)
201{
202	const struct fd_data *data = ptr;
203	struct proc_inode *ei;
204	struct inode *inode;
205
206	inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK);
207	if (!inode)
208		return ERR_PTR(-ENOENT);
209
210	ei = PROC_I(inode);
211	ei->fd = data->fd;
212
213	inode->i_op = &proc_pid_link_inode_operations;
214	inode->i_size = 64;
215
216	ei->op.proc_get_link = proc_fd_link;
217	tid_fd_update_inode(task, inode, data->mode);
218
219	d_set_d_op(dentry, &tid_fd_dentry_operations);
220	return d_splice_alias(inode, dentry);
 
 
 
 
 
 
221}
222
223static struct dentry *proc_lookupfd_common(struct inode *dir,
224					   struct dentry *dentry,
225					   instantiate_t instantiate)
226{
227	struct task_struct *task = get_proc_task(dir);
228	struct fd_data data = {.fd = name_to_int(&dentry->d_name)};
229	struct dentry *result = ERR_PTR(-ENOENT);
230
231	if (!task)
232		goto out_no_task;
233	if (data.fd == ~0U)
234		goto out;
235	if (!tid_fd_mode(task, data.fd, &data.mode))
236		goto out;
237
238	result = instantiate(dentry, task, &data);
239out:
240	put_task_struct(task);
241out_no_task:
242	return result;
243}
244
245static int proc_readfd_common(struct file *file, struct dir_context *ctx,
246			      instantiate_t instantiate)
247{
248	struct task_struct *p = get_proc_task(file_inode(file));
 
249	unsigned int fd;
250
251	if (!p)
252		return -ENOENT;
253
254	if (!dir_emit_dots(file, ctx))
255		goto out;
 
 
 
256
257	rcu_read_lock();
258	for (fd = ctx->pos - 2;; fd++) {
259		struct file *f;
260		struct fd_data data;
261		char name[10 + 1];
262		unsigned int len;
263
264		f = task_lookup_next_fdget_rcu(p, &fd);
265		ctx->pos = fd + 2LL;
266		if (!f)
267			break;
268		data.mode = f->f_mode;
269		rcu_read_unlock();
270		fput(f);
271		data.fd = fd;
272
273		len = snprintf(name, sizeof(name), "%u", fd);
274		if (!proc_fill_cache(file, ctx,
275				     name, len, instantiate, p,
276				     &data))
277			goto out;
278		cond_resched();
279		rcu_read_lock();
280	}
281	rcu_read_unlock();
 
 
282out:
283	put_task_struct(p);
284	return 0;
285}
286
287static int proc_readfd_count(struct inode *inode, loff_t *count)
288{
289	struct task_struct *p = get_proc_task(inode);
290	struct fdtable *fdt;
291
292	if (!p)
293		return -ENOENT;
294
295	task_lock(p);
296	if (p->files) {
297		rcu_read_lock();
298
299		fdt = files_fdtable(p->files);
300		*count = bitmap_weight(fdt->open_fds, fdt->max_fds);
301
302		rcu_read_unlock();
303	}
304	task_unlock(p);
305
306	put_task_struct(p);
307
308	return 0;
309}
310
311static int proc_readfd(struct file *file, struct dir_context *ctx)
312{
313	return proc_readfd_common(file, ctx, proc_fd_instantiate);
314}
315
316const struct file_operations proc_fd_operations = {
317	.read		= generic_read_dir,
318	.iterate_shared	= proc_readfd,
319	.llseek		= generic_file_llseek,
320};
321
322static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
323				    unsigned int flags)
324{
325	return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
326}
327
328/*
329 * /proc/pid/fd needs a special permission handler so that a process can still
330 * access /proc/self/fd after it has executed a setuid().
331 */
332int proc_fd_permission(struct mnt_idmap *idmap,
333		       struct inode *inode, int mask)
334{
335	struct task_struct *p;
336	int rv;
337
338	rv = generic_permission(&nop_mnt_idmap, inode, mask);
339	if (rv == 0)
340		return rv;
341
342	rcu_read_lock();
343	p = pid_task(proc_pid(inode), PIDTYPE_PID);
344	if (p && same_thread_group(p, current))
345		rv = 0;
346	rcu_read_unlock();
347
348	return rv;
349}
350
351static int proc_fd_getattr(struct mnt_idmap *idmap,
352			const struct path *path, struct kstat *stat,
353			u32 request_mask, unsigned int query_flags)
354{
355	struct inode *inode = d_inode(path->dentry);
356	int rv = 0;
357
358	generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
359
360	/* If it's a directory, put the number of open fds there */
361	if (S_ISDIR(inode->i_mode)) {
362		rv = proc_readfd_count(inode, &stat->size);
363		if (rv < 0)
364			return rv;
365	}
366
367	return rv;
368}
369
370const struct inode_operations proc_fd_inode_operations = {
371	.lookup		= proc_lookupfd,
372	.permission	= proc_fd_permission,
373	.getattr	= proc_fd_getattr,
374	.setattr	= proc_setattr,
375};
376
377static struct dentry *proc_fdinfo_instantiate(struct dentry *dentry,
378	struct task_struct *task, const void *ptr)
 
379{
380	const struct fd_data *data = ptr;
381	struct proc_inode *ei;
382	struct inode *inode;
383
384	inode = proc_pid_make_inode(dentry->d_sb, task, S_IFREG | S_IRUGO);
385	if (!inode)
386		return ERR_PTR(-ENOENT);
387
388	ei = PROC_I(inode);
389	ei->fd = data->fd;
390
391	inode->i_fop = &proc_fdinfo_file_operations;
392	tid_fd_update_inode(task, inode, 0);
393
394	d_set_d_op(dentry, &tid_fd_dentry_operations);
395	return d_splice_alias(inode, dentry);
 
 
 
 
 
 
396}
397
398static struct dentry *
399proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags)
400{
401	return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
402}
403
404static int proc_readfdinfo(struct file *file, struct dir_context *ctx)
405{
406	return proc_readfd_common(file, ctx,
407				  proc_fdinfo_instantiate);
408}
409
410static int proc_open_fdinfo(struct inode *inode, struct file *file)
411{
412	int ret = proc_fdinfo_access_allowed(inode);
413
414	if (ret)
415		return ret;
416
417	return 0;
418}
419
420const struct inode_operations proc_fdinfo_inode_operations = {
421	.lookup		= proc_lookupfdinfo,
422	.setattr	= proc_setattr,
423};
424
425const struct file_operations proc_fdinfo_operations = {
426	.open		= proc_open_fdinfo,
427	.read		= generic_read_dir,
428	.iterate_shared	= proc_readfdinfo,
429	.llseek		= generic_file_llseek,
430};

  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};