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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>
8#include <linux/pid.h>
9#include <linux/security.h>
10#include <linux/file.h>
11#include <linux/seq_file.h>
12#include <linux/fs.h>
13
14#include <linux/proc_fs.h>
15
16#include "../mount.h"
17#include "internal.h"
18#include "fd.h"
19
20static int seq_show(struct seq_file *m, void *v)
21{
22 struct files_struct *files = NULL;
23 int f_flags = 0, ret = -ENOENT;
24 struct file *file = NULL;
25 struct task_struct *task;
26
27 task = get_proc_task(m->private);
28 if (!task)
29 return -ENOENT;
30
31 files = get_files_struct(task);
32 put_task_struct(task);
33
34 if (files) {
35 unsigned int fd = proc_fd(m->private);
36
37 spin_lock(&files->file_lock);
38 file = fcheck_files(files, fd);
39 if (file) {
40 struct fdtable *fdt = files_fdtable(files);
41
42 f_flags = file->f_flags;
43 if (close_on_exec(fd, fdt))
44 f_flags |= O_CLOEXEC;
45
46 get_file(file);
47 ret = 0;
48 }
49 spin_unlock(&files->file_lock);
50 put_files_struct(files);
51 }
52
53 if (ret)
54 return ret;
55
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);
59
60 show_fd_locks(m, file, files);
61 if (seq_has_overflowed(m))
62 goto out;
63
64 if (file->f_op->show_fdinfo)
65 file->f_op->show_fdinfo(m, file);
66
67out:
68 fput(file);
69 return 0;
70}
71
72static int seq_fdinfo_open(struct inode *inode, struct file *file)
73{
74 return single_open(file, seq_show, inode);
75}
76
77static const struct file_operations proc_fdinfo_file_operations = {
78 .open = seq_fdinfo_open,
79 .read = seq_read,
80 .llseek = seq_lseek,
81 .release = single_release,
82};
83
84static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
85{
86 struct files_struct *files;
87 struct task_struct *task;
88 struct inode *inode;
89 unsigned 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 task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
112
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;
120 }
121
122 security_task_to_inode(task, inode);
123 put_task_struct(task);
124 return 1;
125 }
126 rcu_read_unlock();
127 put_files_struct(files);
128 }
129 put_task_struct(task);
130 }
131 return 0;
132}
133
134static const struct dentry_operations tid_fd_dentry_operations = {
135 .d_revalidate = tid_fd_revalidate,
136 .d_delete = pid_delete_dentry,
137};
138
139static int proc_fd_link(struct dentry *dentry, struct path *path)
140{
141 struct files_struct *files = NULL;
142 struct task_struct *task;
143 int ret = -ENOENT;
144
145 task = get_proc_task(d_inode(dentry));
146 if (task) {
147 files = get_files_struct(task);
148 put_task_struct(task);
149 }
150
151 if (files) {
152 unsigned int fd = proc_fd(d_inode(dentry));
153 struct file *fd_file;
154
155 spin_lock(&files->file_lock);
156 fd_file = fcheck_files(files, fd);
157 if (fd_file) {
158 *path = fd_file->f_path;
159 path_get(&fd_file->f_path);
160 ret = 0;
161 }
162 spin_unlock(&files->file_lock);
163 put_files_struct(files);
164 }
165
166 return ret;
167}
168
169static int
170proc_fd_instantiate(struct inode *dir, struct dentry *dentry,
171 struct task_struct *task, const void *ptr)
172{
173 unsigned fd = (unsigned long)ptr;
174 struct proc_inode *ei;
175 struct inode *inode;
176
177 inode = proc_pid_make_inode(dir->i_sb, task, S_IFLNK);
178 if (!inode)
179 goto out;
180
181 ei = PROC_I(inode);
182 ei->fd = fd;
183
184 inode->i_op = &proc_pid_link_inode_operations;
185 inode->i_size = 64;
186
187 ei->op.proc_get_link = proc_fd_link;
188
189 d_set_d_op(dentry, &tid_fd_dentry_operations);
190 d_add(dentry, inode);
191
192 /* Close the race of the process dying before we return the dentry */
193 if (tid_fd_revalidate(dentry, 0))
194 return 0;
195 out:
196 return -ENOENT;
197}
198
199static struct dentry *proc_lookupfd_common(struct inode *dir,
200 struct dentry *dentry,
201 instantiate_t instantiate)
202{
203 struct task_struct *task = get_proc_task(dir);
204 int result = -ENOENT;
205 unsigned fd = name_to_int(&dentry->d_name);
206
207 if (!task)
208 goto out_no_task;
209 if (fd == ~0U)
210 goto out;
211
212 result = instantiate(dir, dentry, task, (void *)(unsigned long)fd);
213out:
214 put_task_struct(task);
215out_no_task:
216 return ERR_PTR(result);
217}
218
219static int proc_readfd_common(struct file *file, struct dir_context *ctx,
220 instantiate_t instantiate)
221{
222 struct task_struct *p = get_proc_task(file_inode(file));
223 struct files_struct *files;
224 unsigned int fd;
225
226 if (!p)
227 return -ENOENT;
228
229 if (!dir_emit_dots(file, ctx))
230 goto out;
231 files = get_files_struct(p);
232 if (!files)
233 goto out;
234
235 rcu_read_lock();
236 for (fd = ctx->pos - 2;
237 fd < files_fdtable(files)->max_fds;
238 fd++, ctx->pos++) {
239 char name[10 + 1];
240 int len;
241
242 if (!fcheck_files(files, fd))
243 continue;
244 rcu_read_unlock();
245
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))
250 goto out_fd_loop;
251 cond_resched();
252 rcu_read_lock();
253 }
254 rcu_read_unlock();
255out_fd_loop:
256 put_files_struct(files);
257out:
258 put_task_struct(p);
259 return 0;
260}
261
262static int proc_readfd(struct file *file, struct dir_context *ctx)
263{
264 return proc_readfd_common(file, ctx, proc_fd_instantiate);
265}
266
267const struct file_operations proc_fd_operations = {
268 .read = generic_read_dir,
269 .iterate_shared = proc_readfd,
270 .llseek = generic_file_llseek,
271};
272
273static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
274 unsigned int flags)
275{
276 return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
277}
278
279/*
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().
282 */
283int proc_fd_permission(struct inode *inode, int mask)
284{
285 struct task_struct *p;
286 int rv;
287
288 rv = generic_permission(inode, mask);
289 if (rv == 0)
290 return rv;
291
292 rcu_read_lock();
293 p = pid_task(proc_pid(inode), PIDTYPE_PID);
294 if (p && same_thread_group(p, current))
295 rv = 0;
296 rcu_read_unlock();
297
298 return rv;
299}
300
301const struct inode_operations proc_fd_inode_operations = {
302 .lookup = proc_lookupfd,
303 .permission = proc_fd_permission,
304 .setattr = proc_setattr,
305};
306
307static int
308proc_fdinfo_instantiate(struct inode *dir, struct dentry *dentry,
309 struct task_struct *task, const void *ptr)
310{
311 unsigned fd = (unsigned long)ptr;
312 struct proc_inode *ei;
313 struct inode *inode;
314
315 inode = proc_pid_make_inode(dir->i_sb, task, S_IFREG | S_IRUSR);
316 if (!inode)
317 goto out;
318
319 ei = PROC_I(inode);
320 ei->fd = fd;
321
322 inode->i_fop = &proc_fdinfo_file_operations;
323
324 d_set_d_op(dentry, &tid_fd_dentry_operations);
325 d_add(dentry, inode);
326
327 /* Close the race of the process dying before we return the dentry */
328 if (tid_fd_revalidate(dentry, 0))
329 return 0;
330 out:
331 return -ENOENT;
332}
333
334static struct dentry *
335proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags)
336{
337 return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
338}
339
340static int proc_readfdinfo(struct file *file, struct dir_context *ctx)
341{
342 return proc_readfd_common(file, ctx,
343 proc_fdinfo_instantiate);
344}
345
346const struct inode_operations proc_fdinfo_inode_operations = {
347 .lookup = proc_lookupfdinfo,
348 .setattr = proc_setattr,
349};
350
351const struct file_operations proc_fdinfo_operations = {
352 .read = generic_read_dir,
353 .iterate_shared = proc_readfdinfo,
354 .llseek = generic_file_llseek,
355};
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>
8#include <linux/pid.h>
9#include <linux/ptrace.h>
10#include <linux/security.h>
11#include <linux/file.h>
12#include <linux/seq_file.h>
13#include <linux/fs.h>
14
15#include <linux/proc_fs.h>
16
17#include "../mount.h"
18#include "internal.h"
19#include "fd.h"
20
21static int seq_show(struct seq_file *m, void *v)
22{
23 struct files_struct *files = NULL;
24 int f_flags = 0, ret = -ENOENT;
25 struct file *file = NULL;
26 struct task_struct *task;
27
28 task = get_proc_task(m->private);
29 if (!task)
30 return -ENOENT;
31
32 task_lock(task);
33 files = task->files;
34 if (files) {
35 unsigned int fd = proc_fd(m->private);
36
37 spin_lock(&files->file_lock);
38 file = files_lookup_fd_locked(files, fd);
39 if (file) {
40 struct fdtable *fdt = files_fdtable(files);
41
42 f_flags = file->f_flags;
43 if (close_on_exec(fd, fdt))
44 f_flags |= O_CLOEXEC;
45
46 get_file(file);
47 ret = 0;
48 }
49 spin_unlock(&files->file_lock);
50 }
51 task_unlock(task);
52 put_task_struct(task);
53
54 if (ret)
55 return ret;
56
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);
61
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))
65 goto out;
66
67 if (file->f_op->show_fdinfo)
68 file->f_op->show_fdinfo(m, file);
69
70out:
71 fput(file);
72 return 0;
73}
74
75static int seq_fdinfo_open(struct inode *inode, struct file *file)
76{
77 bool allowed = false;
78 struct task_struct *task = get_proc_task(inode);
79
80 if (!task)
81 return -ESRCH;
82
83 allowed = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
84 put_task_struct(task);
85
86 if (!allowed)
87 return -EACCES;
88
89 return single_open(file, seq_show, inode);
90}
91
92static const struct file_operations proc_fdinfo_file_operations = {
93 .open = seq_fdinfo_open,
94 .read = seq_read,
95 .llseek = seq_lseek,
96 .release = single_release,
97};
98
99static bool tid_fd_mode(struct task_struct *task, unsigned fd, fmode_t *mode)
100{
101 struct file *file;
102
103 rcu_read_lock();
104 file = task_lookup_fd_rcu(task, fd);
105 if (file)
106 *mode = file->f_mode;
107 rcu_read_unlock();
108 return !!file;
109}
110
111static void tid_fd_update_inode(struct task_struct *task, struct inode *inode,
112 fmode_t f_mode)
113{
114 task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
115
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;
123 }
124 security_task_to_inode(task, inode);
125}
126
127static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
128{
129 struct task_struct *task;
130 struct inode *inode;
131 unsigned int fd;
132
133 if (flags & LOOKUP_RCU)
134 return -ECHILD;
135
136 inode = d_inode(dentry);
137 task = get_proc_task(inode);
138 fd = proc_fd(inode);
139
140 if (task) {
141 fmode_t f_mode;
142 if (tid_fd_mode(task, fd, &f_mode)) {
143 tid_fd_update_inode(task, inode, f_mode);
144 put_task_struct(task);
145 return 1;
146 }
147 put_task_struct(task);
148 }
149 return 0;
150}
151
152static const struct dentry_operations tid_fd_dentry_operations = {
153 .d_revalidate = tid_fd_revalidate,
154 .d_delete = pid_delete_dentry,
155};
156
157static int proc_fd_link(struct dentry *dentry, struct path *path)
158{
159 struct task_struct *task;
160 int ret = -ENOENT;
161
162 task = get_proc_task(d_inode(dentry));
163 if (task) {
164 unsigned int fd = proc_fd(d_inode(dentry));
165 struct file *fd_file;
166
167 fd_file = fget_task(task, fd);
168 if (fd_file) {
169 *path = fd_file->f_path;
170 path_get(&fd_file->f_path);
171 ret = 0;
172 fput(fd_file);
173 }
174 put_task_struct(task);
175 }
176
177 return ret;
178}
179
180struct fd_data {
181 fmode_t mode;
182 unsigned fd;
183};
184
185static struct dentry *proc_fd_instantiate(struct dentry *dentry,
186 struct task_struct *task, const void *ptr)
187{
188 const struct fd_data *data = ptr;
189 struct proc_inode *ei;
190 struct inode *inode;
191
192 inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK);
193 if (!inode)
194 return ERR_PTR(-ENOENT);
195
196 ei = PROC_I(inode);
197 ei->fd = data->fd;
198
199 inode->i_op = &proc_pid_link_inode_operations;
200 inode->i_size = 64;
201
202 ei->op.proc_get_link = proc_fd_link;
203 tid_fd_update_inode(task, inode, data->mode);
204
205 d_set_d_op(dentry, &tid_fd_dentry_operations);
206 return d_splice_alias(inode, dentry);
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 struct fd_data data = {.fd = name_to_int(&dentry->d_name)};
215 struct dentry *result = ERR_PTR(-ENOENT);
216
217 if (!task)
218 goto out_no_task;
219 if (data.fd == ~0U)
220 goto out;
221 if (!tid_fd_mode(task, data.fd, &data.mode))
222 goto out;
223
224 result = instantiate(dentry, task, &data);
225out:
226 put_task_struct(task);
227out_no_task:
228 return result;
229}
230
231static int proc_readfd_common(struct file *file, struct dir_context *ctx,
232 instantiate_t instantiate)
233{
234 struct task_struct *p = get_proc_task(file_inode(file));
235 unsigned int fd;
236
237 if (!p)
238 return -ENOENT;
239
240 if (!dir_emit_dots(file, ctx))
241 goto out;
242
243 rcu_read_lock();
244 for (fd = ctx->pos - 2;; fd++) {
245 struct file *f;
246 struct fd_data data;
247 char name[10 + 1];
248 unsigned int len;
249
250 f = task_lookup_next_fd_rcu(p, &fd);
251 ctx->pos = fd + 2LL;
252 if (!f)
253 break;
254 data.mode = f->f_mode;
255 rcu_read_unlock();
256 data.fd = fd;
257
258 len = snprintf(name, sizeof(name), "%u", fd);
259 if (!proc_fill_cache(file, ctx,
260 name, len, instantiate, p,
261 &data))
262 goto out;
263 cond_resched();
264 rcu_read_lock();
265 }
266 rcu_read_unlock();
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_shared = proc_readfd,
280 .llseek = generic_file_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 user_namespace *mnt_userns,
294 struct inode *inode, int mask)
295{
296 struct task_struct *p;
297 int rv;
298
299 rv = generic_permission(&init_user_ns, inode, mask);
300 if (rv == 0)
301 return rv;
302
303 rcu_read_lock();
304 p = pid_task(proc_pid(inode), PIDTYPE_PID);
305 if (p && same_thread_group(p, current))
306 rv = 0;
307 rcu_read_unlock();
308
309 return rv;
310}
311
312const struct inode_operations proc_fd_inode_operations = {
313 .lookup = proc_lookupfd,
314 .permission = proc_fd_permission,
315 .setattr = proc_setattr,
316};
317
318static struct dentry *proc_fdinfo_instantiate(struct dentry *dentry,
319 struct task_struct *task, const void *ptr)
320{
321 const struct fd_data *data = ptr;
322 struct proc_inode *ei;
323 struct inode *inode;
324
325 inode = proc_pid_make_inode(dentry->d_sb, task, S_IFREG | S_IRUGO);
326 if (!inode)
327 return ERR_PTR(-ENOENT);
328
329 ei = PROC_I(inode);
330 ei->fd = data->fd;
331
332 inode->i_fop = &proc_fdinfo_file_operations;
333 tid_fd_update_inode(task, inode, 0);
334
335 d_set_d_op(dentry, &tid_fd_dentry_operations);
336 return d_splice_alias(inode, dentry);
337}
338
339static struct dentry *
340proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags)
341{
342 return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
343}
344
345static int proc_readfdinfo(struct file *file, struct dir_context *ctx)
346{
347 return proc_readfd_common(file, ctx,
348 proc_fdinfo_instantiate);
349}
350
351const struct inode_operations proc_fdinfo_inode_operations = {
352 .lookup = proc_lookupfdinfo,
353 .setattr = proc_setattr,
354};
355
356const struct file_operations proc_fdinfo_operations = {
357 .read = generic_read_dir,
358 .iterate_shared = proc_readfdinfo,
359 .llseek = generic_file_llseek,
360};