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/security.h>
11 #include <linux/file.h>
12 #include <linux/seq_file.h>
15 #include <linux/proc_fs.h>
21 static int seq_show(struct seq_file *m, void *v)
23 struct files_struct *files = NULL;
24 int f_flags = 0, ret = -ENOENT;
25 struct file *file = NULL;
26 struct task_struct *task;
28 task = get_proc_task(m->private);
35 unsigned int fd = proc_fd(m->private);
37 spin_lock(&files->file_lock);
38 file = files_lookup_fd_locked(files, fd);
40 struct fdtable *fdt = files_fdtable(files);
42 f_flags = file->f_flags;
43 if (close_on_exec(fd, fdt))
49 spin_unlock(&files->file_lock);
52 put_task_struct(task);
57 seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\nino:\t%lu\n",
58 (long long)file->f_pos, f_flags,
59 real_mount(file->f_path.mnt)->mnt_id,
60 file_inode(file)->i_ino);
62 /* show_fd_locks() never deferences files so a stale value is safe */
63 show_fd_locks(m, file, files);
64 if (seq_has_overflowed(m))
67 if (file->f_op->show_fdinfo)
68 file->f_op->show_fdinfo(m, file);
75 static int seq_fdinfo_open(struct inode *inode, struct file *file)
78 struct task_struct *task = get_proc_task(inode);
83 allowed = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
84 put_task_struct(task);
89 return single_open(file, seq_show, inode);
92 static const struct file_operations proc_fdinfo_file_operations = {
93 .open = seq_fdinfo_open,
96 .release = single_release,
99 static bool tid_fd_mode(struct task_struct *task, unsigned fd, fmode_t *mode)
104 file = task_lookup_fd_rcu(task, fd);
106 *mode = file->f_mode;
111 static void tid_fd_update_inode(struct task_struct *task, struct inode *inode,
114 task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
116 if (S_ISLNK(inode->i_mode)) {
117 unsigned i_mode = S_IFLNK;
118 if (f_mode & FMODE_READ)
119 i_mode |= S_IRUSR | S_IXUSR;
120 if (f_mode & FMODE_WRITE)
121 i_mode |= S_IWUSR | S_IXUSR;
122 inode->i_mode = i_mode;
124 security_task_to_inode(task, inode);
127 static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
129 struct task_struct *task;
133 if (flags & LOOKUP_RCU)
136 inode = d_inode(dentry);
137 task = get_proc_task(inode);
142 if (tid_fd_mode(task, fd, &f_mode)) {
143 tid_fd_update_inode(task, inode, f_mode);
144 put_task_struct(task);
147 put_task_struct(task);
152 static const struct dentry_operations tid_fd_dentry_operations = {
153 .d_revalidate = tid_fd_revalidate,
154 .d_delete = pid_delete_dentry,
157 static int proc_fd_link(struct dentry *dentry, struct path *path)
159 struct task_struct *task;
162 task = get_proc_task(d_inode(dentry));
164 unsigned int fd = proc_fd(d_inode(dentry));
165 struct file *fd_file;
167 fd_file = fget_task(task, fd);
169 *path = fd_file->f_path;
170 path_get(&fd_file->f_path);
174 put_task_struct(task);
185 static struct dentry *proc_fd_instantiate(struct dentry *dentry,
186 struct task_struct *task, const void *ptr)
188 const struct fd_data *data = ptr;
189 struct proc_inode *ei;
192 inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK);
194 return ERR_PTR(-ENOENT);
199 inode->i_op = &proc_pid_link_inode_operations;
202 ei->op.proc_get_link = proc_fd_link;
203 tid_fd_update_inode(task, inode, data->mode);
205 d_set_d_op(dentry, &tid_fd_dentry_operations);
206 return d_splice_alias(inode, dentry);
209 static struct dentry *proc_lookupfd_common(struct inode *dir,
210 struct dentry *dentry,
211 instantiate_t instantiate)
213 struct task_struct *task = get_proc_task(dir);
214 struct fd_data data = {.fd = name_to_int(&dentry->d_name)};
215 struct dentry *result = ERR_PTR(-ENOENT);
221 if (!tid_fd_mode(task, data.fd, &data.mode))
224 result = instantiate(dentry, task, &data);
226 put_task_struct(task);
231 static int proc_readfd_common(struct file *file, struct dir_context *ctx,
232 instantiate_t instantiate)
234 struct task_struct *p = get_proc_task(file_inode(file));
240 if (!dir_emit_dots(file, ctx))
244 for (fd = ctx->pos - 2;; fd++) {
250 f = task_lookup_next_fd_rcu(p, &fd);
254 data.mode = f->f_mode;
258 len = snprintf(name, sizeof(name), "%u", fd);
259 if (!proc_fill_cache(file, ctx,
260 name, len, instantiate, p,
272 static int proc_readfd(struct file *file, struct dir_context *ctx)
274 return proc_readfd_common(file, ctx, proc_fd_instantiate);
277 const struct file_operations proc_fd_operations = {
278 .read = generic_read_dir,
279 .iterate_shared = proc_readfd,
280 .llseek = generic_file_llseek,
283 static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
286 return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
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().
293 int proc_fd_permission(struct user_namespace *mnt_userns,
294 struct inode *inode, int mask)
296 struct task_struct *p;
299 rv = generic_permission(&init_user_ns, inode, mask);
304 p = pid_task(proc_pid(inode), PIDTYPE_PID);
305 if (p && same_thread_group(p, current))
312 const struct inode_operations proc_fd_inode_operations = {
313 .lookup = proc_lookupfd,
314 .permission = proc_fd_permission,
315 .setattr = proc_setattr,
318 static struct dentry *proc_fdinfo_instantiate(struct dentry *dentry,
319 struct task_struct *task, const void *ptr)
321 const struct fd_data *data = ptr;
322 struct proc_inode *ei;
325 inode = proc_pid_make_inode(dentry->d_sb, task, S_IFREG | S_IRUGO);
327 return ERR_PTR(-ENOENT);
332 inode->i_fop = &proc_fdinfo_file_operations;
333 tid_fd_update_inode(task, inode, 0);
335 d_set_d_op(dentry, &tid_fd_dentry_operations);
336 return d_splice_alias(inode, dentry);
339 static struct dentry *
340 proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags)
342 return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
345 static int proc_readfdinfo(struct file *file, struct dir_context *ctx)
347 return proc_readfd_common(file, ctx,
348 proc_fdinfo_instantiate);
351 const struct inode_operations proc_fdinfo_inode_operations = {
352 .lookup = proc_lookupfdinfo,
353 .setattr = proc_setattr,
356 const struct file_operations proc_fdinfo_operations = {
357 .read = generic_read_dir,
358 .iterate_shared = proc_readfdinfo,
359 .llseek = generic_file_llseek,