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