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/security.h>
10 #include <linux/file.h>
11 #include <linux/seq_file.h>
14 #include <linux/proc_fs.h>
20 static int seq_show(struct seq_file *m, void *v)
22 struct files_struct *files = NULL;
23 int f_flags = 0, ret = -ENOENT;
24 struct file *file = NULL;
25 struct task_struct *task;
27 task = get_proc_task(m->private);
31 files = get_files_struct(task);
32 put_task_struct(task);
35 unsigned int fd = proc_fd(m->private);
37 spin_lock(&files->file_lock);
38 file = fcheck_files(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);
50 put_files_struct(files);
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);
60 show_fd_locks(m, file, files);
61 if (seq_has_overflowed(m))
64 if (file->f_op->show_fdinfo)
65 file->f_op->show_fdinfo(m, file);
72 static int seq_fdinfo_open(struct inode *inode, struct file *file)
74 return single_open(file, seq_show, inode);
77 static const struct file_operations proc_fdinfo_file_operations = {
78 .open = seq_fdinfo_open,
81 .release = single_release,
84 static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
86 struct files_struct *files;
87 struct task_struct *task;
91 if (flags & LOOKUP_RCU)
94 inode = d_inode(dentry);
95 task = get_proc_task(inode);
99 files = get_files_struct(task);
104 file = fcheck_files(files, fd);
106 unsigned f_mode = file->f_mode;
109 put_files_struct(files);
111 task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
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;
122 security_task_to_inode(task, inode);
123 put_task_struct(task);
127 put_files_struct(files);
129 put_task_struct(task);
134 static const struct dentry_operations tid_fd_dentry_operations = {
135 .d_revalidate = tid_fd_revalidate,
136 .d_delete = pid_delete_dentry,
139 static int proc_fd_link(struct dentry *dentry, struct path *path)
141 struct files_struct *files = NULL;
142 struct task_struct *task;
145 task = get_proc_task(d_inode(dentry));
147 files = get_files_struct(task);
148 put_task_struct(task);
152 unsigned int fd = proc_fd(d_inode(dentry));
153 struct file *fd_file;
155 spin_lock(&files->file_lock);
156 fd_file = fcheck_files(files, fd);
158 *path = fd_file->f_path;
159 path_get(&fd_file->f_path);
162 spin_unlock(&files->file_lock);
163 put_files_struct(files);
170 proc_fd_instantiate(struct inode *dir, struct dentry *dentry,
171 struct task_struct *task, const void *ptr)
173 unsigned fd = (unsigned long)ptr;
174 struct proc_inode *ei;
177 inode = proc_pid_make_inode(dir->i_sb, task, S_IFLNK);
184 inode->i_op = &proc_pid_link_inode_operations;
187 ei->op.proc_get_link = proc_fd_link;
189 d_set_d_op(dentry, &tid_fd_dentry_operations);
190 d_add(dentry, inode);
192 /* Close the race of the process dying before we return the dentry */
193 if (tid_fd_revalidate(dentry, 0))
199 static struct dentry *proc_lookupfd_common(struct inode *dir,
200 struct dentry *dentry,
201 instantiate_t instantiate)
203 struct task_struct *task = get_proc_task(dir);
204 int result = -ENOENT;
205 unsigned fd = name_to_int(&dentry->d_name);
212 result = instantiate(dir, dentry, task, (void *)(unsigned long)fd);
214 put_task_struct(task);
216 return ERR_PTR(result);
219 static int proc_readfd_common(struct file *file, struct dir_context *ctx,
220 instantiate_t instantiate)
222 struct task_struct *p = get_proc_task(file_inode(file));
223 struct files_struct *files;
229 if (!dir_emit_dots(file, ctx))
231 files = get_files_struct(p);
236 for (fd = ctx->pos - 2;
237 fd < files_fdtable(files)->max_fds;
239 char name[PROC_NUMBUF];
242 if (!fcheck_files(files, fd))
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))
256 put_files_struct(files);
262 static int proc_readfd(struct file *file, struct dir_context *ctx)
264 return proc_readfd_common(file, ctx, proc_fd_instantiate);
267 const struct file_operations proc_fd_operations = {
268 .read = generic_read_dir,
269 .iterate_shared = proc_readfd,
270 .llseek = generic_file_llseek,
273 static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
276 return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
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().
283 int proc_fd_permission(struct inode *inode, int mask)
285 struct task_struct *p;
288 rv = generic_permission(inode, mask);
293 p = pid_task(proc_pid(inode), PIDTYPE_PID);
294 if (p && same_thread_group(p, current))
301 const struct inode_operations proc_fd_inode_operations = {
302 .lookup = proc_lookupfd,
303 .permission = proc_fd_permission,
304 .setattr = proc_setattr,
308 proc_fdinfo_instantiate(struct inode *dir, struct dentry *dentry,
309 struct task_struct *task, const void *ptr)
311 unsigned fd = (unsigned long)ptr;
312 struct proc_inode *ei;
315 inode = proc_pid_make_inode(dir->i_sb, task, S_IFREG | S_IRUSR);
322 inode->i_fop = &proc_fdinfo_file_operations;
324 d_set_d_op(dentry, &tid_fd_dentry_operations);
325 d_add(dentry, inode);
327 /* Close the race of the process dying before we return the dentry */
328 if (tid_fd_revalidate(dentry, 0))
334 static struct dentry *
335 proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags)
337 return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
340 static int proc_readfdinfo(struct file *file, struct dir_context *ctx)
342 return proc_readfd_common(file, ctx,
343 proc_fdinfo_instantiate);
346 const struct inode_operations proc_fdinfo_inode_operations = {
347 .lookup = proc_lookupfdinfo,
348 .setattr = proc_setattr,
351 const struct file_operations proc_fdinfo_operations = {
352 .read = generic_read_dir,
353 .iterate_shared = proc_readfdinfo,
354 .llseek = generic_file_llseek,