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>
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>
15 #include <linux/filelock.h>
17 #include <linux/proc_fs.h>
23 static int seq_show(struct seq_file *m, void *v)
25 struct files_struct *files = NULL;
26 int f_flags = 0, ret = -ENOENT;
27 struct file *file = NULL;
28 struct task_struct *task;
30 task = get_proc_task(m->private);
37 unsigned int fd = proc_fd(m->private);
39 spin_lock(&files->file_lock);
40 file = files_lookup_fd_locked(files, fd);
42 struct fdtable *fdt = files_fdtable(files);
44 f_flags = file->f_flags;
45 if (close_on_exec(fd, fdt))
51 spin_unlock(&files->file_lock);
54 put_task_struct(task);
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);
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))
69 if (file->f_op->show_fdinfo)
70 file->f_op->show_fdinfo(m, file);
77 static int proc_fdinfo_access_allowed(struct inode *inode)
80 struct task_struct *task = get_proc_task(inode);
85 allowed = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
86 put_task_struct(task);
94 static int seq_fdinfo_open(struct inode *inode, struct file *file)
96 int ret = proc_fdinfo_access_allowed(inode);
101 return single_open(file, seq_show, inode);
104 static const struct file_operations proc_fdinfo_file_operations = {
105 .open = seq_fdinfo_open,
108 .release = single_release,
111 static bool tid_fd_mode(struct task_struct *task, unsigned fd, fmode_t *mode)
116 file = task_lookup_fd_rcu(task, fd);
118 *mode = file->f_mode;
123 static void tid_fd_update_inode(struct task_struct *task, struct inode *inode,
126 task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
128 if (S_ISLNK(inode->i_mode)) {
129 unsigned i_mode = S_IFLNK;
130 if (f_mode & FMODE_READ)
131 i_mode |= S_IRUSR | S_IXUSR;
132 if (f_mode & FMODE_WRITE)
133 i_mode |= S_IWUSR | S_IXUSR;
134 inode->i_mode = i_mode;
136 security_task_to_inode(task, inode);
139 static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
141 struct task_struct *task;
145 if (flags & LOOKUP_RCU)
148 inode = d_inode(dentry);
149 task = get_proc_task(inode);
154 if (tid_fd_mode(task, fd, &f_mode)) {
155 tid_fd_update_inode(task, inode, f_mode);
156 put_task_struct(task);
159 put_task_struct(task);
164 static const struct dentry_operations tid_fd_dentry_operations = {
165 .d_revalidate = tid_fd_revalidate,
166 .d_delete = pid_delete_dentry,
169 static int proc_fd_link(struct dentry *dentry, struct path *path)
171 struct task_struct *task;
174 task = get_proc_task(d_inode(dentry));
176 unsigned int fd = proc_fd(d_inode(dentry));
177 struct file *fd_file;
179 fd_file = fget_task(task, fd);
181 *path = fd_file->f_path;
182 path_get(&fd_file->f_path);
186 put_task_struct(task);
197 static struct dentry *proc_fd_instantiate(struct dentry *dentry,
198 struct task_struct *task, const void *ptr)
200 const struct fd_data *data = ptr;
201 struct proc_inode *ei;
204 inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK);
206 return ERR_PTR(-ENOENT);
211 inode->i_op = &proc_pid_link_inode_operations;
214 ei->op.proc_get_link = proc_fd_link;
215 tid_fd_update_inode(task, inode, data->mode);
217 d_set_d_op(dentry, &tid_fd_dentry_operations);
218 return d_splice_alias(inode, dentry);
221 static struct dentry *proc_lookupfd_common(struct inode *dir,
222 struct dentry *dentry,
223 instantiate_t instantiate)
225 struct task_struct *task = get_proc_task(dir);
226 struct fd_data data = {.fd = name_to_int(&dentry->d_name)};
227 struct dentry *result = ERR_PTR(-ENOENT);
233 if (!tid_fd_mode(task, data.fd, &data.mode))
236 result = instantiate(dentry, task, &data);
238 put_task_struct(task);
243 static int proc_readfd_common(struct file *file, struct dir_context *ctx,
244 instantiate_t instantiate)
246 struct task_struct *p = get_proc_task(file_inode(file));
252 if (!dir_emit_dots(file, ctx))
256 for (fd = ctx->pos - 2;; fd++) {
262 f = task_lookup_next_fd_rcu(p, &fd);
266 data.mode = f->f_mode;
270 len = snprintf(name, sizeof(name), "%u", fd);
271 if (!proc_fill_cache(file, ctx,
272 name, len, instantiate, p,
284 static int proc_readfd_count(struct inode *inode, loff_t *count)
286 struct task_struct *p = get_proc_task(inode);
296 fdt = files_fdtable(p->files);
297 *count = bitmap_weight(fdt->open_fds, fdt->max_fds);
308 static int proc_readfd(struct file *file, struct dir_context *ctx)
310 return proc_readfd_common(file, ctx, proc_fd_instantiate);
313 const struct file_operations proc_fd_operations = {
314 .read = generic_read_dir,
315 .iterate_shared = proc_readfd,
316 .llseek = generic_file_llseek,
319 static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
322 return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
326 * /proc/pid/fd needs a special permission handler so that a process can still
327 * access /proc/self/fd after it has executed a setuid().
329 int proc_fd_permission(struct mnt_idmap *idmap,
330 struct inode *inode, int mask)
332 struct task_struct *p;
335 rv = generic_permission(&nop_mnt_idmap, inode, mask);
340 p = pid_task(proc_pid(inode), PIDTYPE_PID);
341 if (p && same_thread_group(p, current))
348 static int proc_fd_getattr(struct mnt_idmap *idmap,
349 const struct path *path, struct kstat *stat,
350 u32 request_mask, unsigned int query_flags)
352 struct inode *inode = d_inode(path->dentry);
355 generic_fillattr(&nop_mnt_idmap, inode, stat);
357 /* If it's a directory, put the number of open fds there */
358 if (S_ISDIR(inode->i_mode)) {
359 rv = proc_readfd_count(inode, &stat->size);
367 const struct inode_operations proc_fd_inode_operations = {
368 .lookup = proc_lookupfd,
369 .permission = proc_fd_permission,
370 .getattr = proc_fd_getattr,
371 .setattr = proc_setattr,
374 static struct dentry *proc_fdinfo_instantiate(struct dentry *dentry,
375 struct task_struct *task, const void *ptr)
377 const struct fd_data *data = ptr;
378 struct proc_inode *ei;
381 inode = proc_pid_make_inode(dentry->d_sb, task, S_IFREG | S_IRUGO);
383 return ERR_PTR(-ENOENT);
388 inode->i_fop = &proc_fdinfo_file_operations;
389 tid_fd_update_inode(task, inode, 0);
391 d_set_d_op(dentry, &tid_fd_dentry_operations);
392 return d_splice_alias(inode, dentry);
395 static struct dentry *
396 proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags)
398 return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
401 static int proc_readfdinfo(struct file *file, struct dir_context *ctx)
403 return proc_readfd_common(file, ctx,
404 proc_fdinfo_instantiate);
407 static int proc_open_fdinfo(struct inode *inode, struct file *file)
409 int ret = proc_fdinfo_access_allowed(inode);
417 const struct inode_operations proc_fdinfo_inode_operations = {
418 .lookup = proc_lookupfdinfo,
419 .setattr = proc_setattr,
422 const struct file_operations proc_fdinfo_operations = {
423 .open = proc_open_fdinfo,
424 .read = generic_read_dir,
425 .iterate_shared = proc_readfdinfo,
426 .llseek = generic_file_llseek,