1#include <linux/sched.h>
  2#include <linux/errno.h>
  3#include <linux/dcache.h>
  4#include <linux/path.h>
  5#include <linux/fdtable.h>
  6#include <linux/namei.h>
  7#include <linux/pid.h>
  8#include <linux/security.h>
  9#include <linux/file.h>
 10#include <linux/seq_file.h>
 11#include <linux/fs.h>
 12
 13#include <linux/proc_fs.h>
 14
 15#include "../mount.h"
 16#include "internal.h"
 17#include "fd.h"
 18
 19static int seq_show(struct seq_file *m, void *v)
 20{
 21	struct files_struct *files = NULL;
 22	int f_flags = 0, ret = -ENOENT;
 23	struct file *file = NULL;
 24	struct task_struct *task;
 25
 26	task = get_proc_task(m->private);
 27	if (!task)
 28		return -ENOENT;
 29
 30	files = get_files_struct(task);
 31	put_task_struct(task);
 32
 33	if (files) {
 34		int fd = proc_fd(m->private);
 35
 36		spin_lock(&files->file_lock);
 37		file = fcheck_files(files, fd);
 38		if (file) {
 39			struct fdtable *fdt = files_fdtable(files);
 40
 41			f_flags = file->f_flags;
 42			if (close_on_exec(fd, fdt))
 43				f_flags |= O_CLOEXEC;
 44
 45			get_file(file);
 46			ret = 0;
 47		}
 48		spin_unlock(&files->file_lock);
 49		put_files_struct(files);
 50	}
 51
 52	if (ret)
 53		return ret;
 54
 55	seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\n",
 56		   (long long)file->f_pos, f_flags,
 57		   real_mount(file->f_path.mnt)->mnt_id);
 58
 59	show_fd_locks(m, file, files);
 60	if (seq_has_overflowed(m))
 61		goto out;
 62
 63	if (file->f_op->show_fdinfo)
 64		file->f_op->show_fdinfo(m, file);
 65
 66out:
 67	fput(file);
 68	return 0;
 69}
 70
 71static int seq_fdinfo_open(struct inode *inode, struct file *file)
 72{
 73	return single_open(file, seq_show, inode);
 74}
 75
 76static const struct file_operations proc_fdinfo_file_operations = {
 77	.open		= seq_fdinfo_open,
 78	.read		= seq_read,
 79	.llseek		= seq_lseek,
 80	.release	= single_release,
 81};
 82
 83static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
 84{
 85	struct files_struct *files;
 86	struct task_struct *task;
 87	const struct cred *cred;
 88	struct inode *inode;
 89	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				if (task_dumpable(task)) {
112					rcu_read_lock();
113					cred = __task_cred(task);
114					inode->i_uid = cred->euid;
115					inode->i_gid = cred->egid;
116					rcu_read_unlock();
117				} else {
118					inode->i_uid = GLOBAL_ROOT_UID;
119					inode->i_gid = GLOBAL_ROOT_GID;
120				}
121
122				if (S_ISLNK(inode->i_mode)) {
123					unsigned i_mode = S_IFLNK;
124					if (f_mode & FMODE_READ)
125						i_mode |= S_IRUSR | S_IXUSR;
126					if (f_mode & FMODE_WRITE)
127						i_mode |= S_IWUSR | S_IXUSR;
128					inode->i_mode = i_mode;
129				}
130
131				security_task_to_inode(task, inode);
132				put_task_struct(task);
133				return 1;
134			}
135			rcu_read_unlock();
136			put_files_struct(files);
137		}
138		put_task_struct(task);
139	}
140	return 0;
141}
142
143static const struct dentry_operations tid_fd_dentry_operations = {
144	.d_revalidate	= tid_fd_revalidate,
145	.d_delete	= pid_delete_dentry,
146};
147
148static int proc_fd_link(struct dentry *dentry, struct path *path)
149{
150	struct files_struct *files = NULL;
151	struct task_struct *task;
152	int ret = -ENOENT;
153
154	task = get_proc_task(d_inode(dentry));
155	if (task) {
156		files = get_files_struct(task);
157		put_task_struct(task);
158	}
159
160	if (files) {
161		int fd = proc_fd(d_inode(dentry));
162		struct file *fd_file;
163
164		spin_lock(&files->file_lock);
165		fd_file = fcheck_files(files, fd);
166		if (fd_file) {
167			*path = fd_file->f_path;
168			path_get(&fd_file->f_path);
169			ret = 0;
170		}
171		spin_unlock(&files->file_lock);
172		put_files_struct(files);
173	}
174
175	return ret;
176}
177
178static int
179proc_fd_instantiate(struct inode *dir, struct dentry *dentry,
180		    struct task_struct *task, const void *ptr)
181{
182	unsigned fd = (unsigned long)ptr;
183	struct proc_inode *ei;
184	struct inode *inode;
185
186	inode = proc_pid_make_inode(dir->i_sb, task);
187	if (!inode)
188		goto out;
189
190	ei = PROC_I(inode);
191	ei->fd = fd;
192
193	inode->i_mode = S_IFLNK;
194	inode->i_op = &proc_pid_link_inode_operations;
195	inode->i_size = 64;
196
197	ei->op.proc_get_link = proc_fd_link;
198
199	d_set_d_op(dentry, &tid_fd_dentry_operations);
200	d_add(dentry, inode);
201
202	/* Close the race of the process dying before we return the dentry */
203	if (tid_fd_revalidate(dentry, 0))
204		return 0;
205 out:
206	return -ENOENT;
207}
208
209static struct dentry *proc_lookupfd_common(struct inode *dir,
210					   struct dentry *dentry,
211					   instantiate_t instantiate)
212{
213	struct task_struct *task = get_proc_task(dir);
214	int result = -ENOENT;
215	unsigned fd = name_to_int(&dentry->d_name);
216
217	if (!task)
218		goto out_no_task;
219	if (fd == ~0U)
220		goto out;
221
222	result = instantiate(dir, dentry, task, (void *)(unsigned long)fd);
223out:
224	put_task_struct(task);
225out_no_task:
226	return ERR_PTR(result);
227}
228
229static int proc_readfd_common(struct file *file, struct dir_context *ctx,
230			      instantiate_t instantiate)
231{
232	struct task_struct *p = get_proc_task(file_inode(file));
233	struct files_struct *files;
234	unsigned int fd;
235
236	if (!p)
237		return -ENOENT;
238
239	if (!dir_emit_dots(file, ctx))
240		goto out;
241	files = get_files_struct(p);
242	if (!files)
243		goto out;
244
245	rcu_read_lock();
246	for (fd = ctx->pos - 2;
247	     fd < files_fdtable(files)->max_fds;
248	     fd++, ctx->pos++) {
249		char name[PROC_NUMBUF];
250		int len;
251
252		if (!fcheck_files(files, fd))
253			continue;
254		rcu_read_unlock();
255
256		len = snprintf(name, sizeof(name), "%d", fd);
257		if (!proc_fill_cache(file, ctx,
258				     name, len, instantiate, p,
259				     (void *)(unsigned long)fd))
260			goto out_fd_loop;
261		cond_resched();
262		rcu_read_lock();
263	}
264	rcu_read_unlock();
265out_fd_loop:
266	put_files_struct(files);
267out:
268	put_task_struct(p);
269	return 0;
270}
271
272static int proc_readfd(struct file *file, struct dir_context *ctx)
273{
274	return proc_readfd_common(file, ctx, proc_fd_instantiate);
275}
276
277const struct file_operations proc_fd_operations = {
278	.read		= generic_read_dir,
279	.iterate	= proc_readfd,
280	.llseek		= default_llseek,
281};
282
283static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
284				    unsigned int flags)
285{
286	return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
287}
288
289/*
290 * /proc/pid/fd needs a special permission handler so that a process can still
291 * access /proc/self/fd after it has executed a setuid().
292 */
293int proc_fd_permission(struct inode *inode, int mask)
294{
295	struct task_struct *p;
296	int rv;
297
298	rv = generic_permission(inode, mask);
299	if (rv == 0)
300		return rv;
301
302	rcu_read_lock();
303	p = pid_task(proc_pid(inode), PIDTYPE_PID);
304	if (p && same_thread_group(p, current))
305		rv = 0;
306	rcu_read_unlock();
307
308	return rv;
309}
310
311const struct inode_operations proc_fd_inode_operations = {
312	.lookup		= proc_lookupfd,
313	.permission	= proc_fd_permission,
314	.setattr	= proc_setattr,
315};
316
317static int
318proc_fdinfo_instantiate(struct inode *dir, struct dentry *dentry,
319			struct task_struct *task, const void *ptr)
320{
321	unsigned fd = (unsigned long)ptr;
322	struct proc_inode *ei;
323	struct inode *inode;
324
325	inode = proc_pid_make_inode(dir->i_sb, task);
326	if (!inode)
327		goto out;
328
329	ei = PROC_I(inode);
330	ei->fd = fd;
331
332	inode->i_mode = S_IFREG | S_IRUSR;
333	inode->i_fop = &proc_fdinfo_file_operations;
334
335	d_set_d_op(dentry, &tid_fd_dentry_operations);
336	d_add(dentry, inode);
337
338	/* Close the race of the process dying before we return the dentry */
339	if (tid_fd_revalidate(dentry, 0))
340		return 0;
341 out:
342	return -ENOENT;
343}
344
345static struct dentry *
346proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags)
347{
348	return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
349}
350
351static int proc_readfdinfo(struct file *file, struct dir_context *ctx)
352{
353	return proc_readfd_common(file, ctx,
354				  proc_fdinfo_instantiate);
355}
356
357const struct inode_operations proc_fdinfo_inode_operations = {
358	.lookup		= proc_lookupfdinfo,
359	.setattr	= proc_setattr,
360};
361
362const struct file_operations proc_fdinfo_operations = {
363	.read		= generic_read_dir,
364	.iterate	= proc_readfdinfo,
365	.llseek		= default_llseek,
366};