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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 bool tid_fd_mode(struct task_struct *task, unsigned fd, fmode_t *mode)
85{
86 struct files_struct *files = get_files_struct(task);
87 struct file *file;
88
89 if (!files)
90 return false;
91
92 rcu_read_lock();
93 file = fcheck_files(files, fd);
94 if (file)
95 *mode = file->f_mode;
96 rcu_read_unlock();
97 put_files_struct(files);
98 return !!file;
99}
100
101static void tid_fd_update_inode(struct task_struct *task, struct inode *inode,
102 fmode_t f_mode)
103{
104 task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
105
106 if (S_ISLNK(inode->i_mode)) {
107 unsigned i_mode = S_IFLNK;
108 if (f_mode & FMODE_READ)
109 i_mode |= S_IRUSR | S_IXUSR;
110 if (f_mode & FMODE_WRITE)
111 i_mode |= S_IWUSR | S_IXUSR;
112 inode->i_mode = i_mode;
113 }
114 security_task_to_inode(task, inode);
115}
116
117static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
118{
119 struct task_struct *task;
120 struct inode *inode;
121 unsigned int fd;
122
123 if (flags & LOOKUP_RCU)
124 return -ECHILD;
125
126 inode = d_inode(dentry);
127 task = get_proc_task(inode);
128 fd = proc_fd(inode);
129
130 if (task) {
131 fmode_t f_mode;
132 if (tid_fd_mode(task, fd, &f_mode)) {
133 tid_fd_update_inode(task, inode, f_mode);
134 put_task_struct(task);
135 return 1;
136 }
137 put_task_struct(task);
138 }
139 return 0;
140}
141
142static const struct dentry_operations tid_fd_dentry_operations = {
143 .d_revalidate = tid_fd_revalidate,
144 .d_delete = pid_delete_dentry,
145};
146
147static int proc_fd_link(struct dentry *dentry, struct path *path)
148{
149 struct files_struct *files = NULL;
150 struct task_struct *task;
151 int ret = -ENOENT;
152
153 task = get_proc_task(d_inode(dentry));
154 if (task) {
155 files = get_files_struct(task);
156 put_task_struct(task);
157 }
158
159 if (files) {
160 unsigned int fd = proc_fd(d_inode(dentry));
161 struct file *fd_file;
162
163 spin_lock(&files->file_lock);
164 fd_file = fcheck_files(files, fd);
165 if (fd_file) {
166 *path = fd_file->f_path;
167 path_get(&fd_file->f_path);
168 ret = 0;
169 }
170 spin_unlock(&files->file_lock);
171 put_files_struct(files);
172 }
173
174 return ret;
175}
176
177struct fd_data {
178 fmode_t mode;
179 unsigned fd;
180};
181
182static struct dentry *proc_fd_instantiate(struct dentry *dentry,
183 struct task_struct *task, const void *ptr)
184{
185 const struct fd_data *data = ptr;
186 struct proc_inode *ei;
187 struct inode *inode;
188
189 inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK);
190 if (!inode)
191 return ERR_PTR(-ENOENT);
192
193 ei = PROC_I(inode);
194 ei->fd = data->fd;
195
196 inode->i_op = &proc_pid_link_inode_operations;
197 inode->i_size = 64;
198
199 ei->op.proc_get_link = proc_fd_link;
200 tid_fd_update_inode(task, inode, data->mode);
201
202 d_set_d_op(dentry, &tid_fd_dentry_operations);
203 return d_splice_alias(inode, dentry);
204}
205
206static struct dentry *proc_lookupfd_common(struct inode *dir,
207 struct dentry *dentry,
208 instantiate_t instantiate)
209{
210 struct task_struct *task = get_proc_task(dir);
211 struct fd_data data = {.fd = name_to_int(&dentry->d_name)};
212 struct dentry *result = ERR_PTR(-ENOENT);
213
214 if (!task)
215 goto out_no_task;
216 if (data.fd == ~0U)
217 goto out;
218 if (!tid_fd_mode(task, data.fd, &data.mode))
219 goto out;
220
221 result = instantiate(dentry, task, &data);
222out:
223 put_task_struct(task);
224out_no_task:
225 return result;
226}
227
228static int proc_readfd_common(struct file *file, struct dir_context *ctx,
229 instantiate_t instantiate)
230{
231 struct task_struct *p = get_proc_task(file_inode(file));
232 struct files_struct *files;
233 unsigned int fd;
234
235 if (!p)
236 return -ENOENT;
237
238 if (!dir_emit_dots(file, ctx))
239 goto out;
240 files = get_files_struct(p);
241 if (!files)
242 goto out;
243
244 rcu_read_lock();
245 for (fd = ctx->pos - 2;
246 fd < files_fdtable(files)->max_fds;
247 fd++, ctx->pos++) {
248 struct file *f;
249 struct fd_data data;
250 char name[10 + 1];
251 unsigned int len;
252
253 f = fcheck_files(files, fd);
254 if (!f)
255 continue;
256 data.mode = f->f_mode;
257 rcu_read_unlock();
258 data.fd = fd;
259
260 len = snprintf(name, sizeof(name), "%u", fd);
261 if (!proc_fill_cache(file, ctx,
262 name, len, instantiate, p,
263 &data))
264 goto out_fd_loop;
265 cond_resched();
266 rcu_read_lock();
267 }
268 rcu_read_unlock();
269out_fd_loop:
270 put_files_struct(files);
271out:
272 put_task_struct(p);
273 return 0;
274}
275
276static int proc_readfd(struct file *file, struct dir_context *ctx)
277{
278 return proc_readfd_common(file, ctx, proc_fd_instantiate);
279}
280
281const struct file_operations proc_fd_operations = {
282 .read = generic_read_dir,
283 .iterate_shared = proc_readfd,
284 .llseek = generic_file_llseek,
285};
286
287static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
288 unsigned int flags)
289{
290 return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
291}
292
293/*
294 * /proc/pid/fd needs a special permission handler so that a process can still
295 * access /proc/self/fd after it has executed a setuid().
296 */
297int proc_fd_permission(struct inode *inode, int mask)
298{
299 struct task_struct *p;
300 int rv;
301
302 rv = generic_permission(inode, mask);
303 if (rv == 0)
304 return rv;
305
306 rcu_read_lock();
307 p = pid_task(proc_pid(inode), PIDTYPE_PID);
308 if (p && same_thread_group(p, current))
309 rv = 0;
310 rcu_read_unlock();
311
312 return rv;
313}
314
315const struct inode_operations proc_fd_inode_operations = {
316 .lookup = proc_lookupfd,
317 .permission = proc_fd_permission,
318 .setattr = proc_setattr,
319};
320
321static struct dentry *proc_fdinfo_instantiate(struct dentry *dentry,
322 struct task_struct *task, const void *ptr)
323{
324 const struct fd_data *data = ptr;
325 struct proc_inode *ei;
326 struct inode *inode;
327
328 inode = proc_pid_make_inode(dentry->d_sb, task, S_IFREG | S_IRUSR);
329 if (!inode)
330 return ERR_PTR(-ENOENT);
331
332 ei = PROC_I(inode);
333 ei->fd = data->fd;
334
335 inode->i_fop = &proc_fdinfo_file_operations;
336 tid_fd_update_inode(task, inode, 0);
337
338 d_set_d_op(dentry, &tid_fd_dentry_operations);
339 return d_splice_alias(inode, dentry);
340}
341
342static struct dentry *
343proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags)
344{
345 return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
346}
347
348static int proc_readfdinfo(struct file *file, struct dir_context *ctx)
349{
350 return proc_readfd_common(file, ctx,
351 proc_fdinfo_instantiate);
352}
353
354const struct inode_operations proc_fdinfo_inode_operations = {
355 .lookup = proc_lookupfdinfo,
356 .setattr = proc_setattr,
357};
358
359const struct file_operations proc_fdinfo_operations = {
360 .read = generic_read_dir,
361 .iterate_shared = proc_readfdinfo,
362 .llseek = generic_file_llseek,
363};
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/bitmap.h>
11#include <linux/security.h>
12#include <linux/file.h>
13#include <linux/seq_file.h>
14#include <linux/fs.h>
15#include <linux/filelock.h>
16
17#include <linux/proc_fs.h>
18
19#include "../mount.h"
20#include "internal.h"
21#include "fd.h"
22
23static int seq_show(struct seq_file *m, void *v)
24{
25 struct files_struct *files = NULL;
26 int f_flags = 0, ret = -ENOENT;
27 struct file *file = NULL;
28 struct task_struct *task;
29
30 task = get_proc_task(m->private);
31 if (!task)
32 return -ENOENT;
33
34 task_lock(task);
35 files = task->files;
36 if (files) {
37 unsigned int fd = proc_fd(m->private);
38
39 spin_lock(&files->file_lock);
40 file = files_lookup_fd_locked(files, fd);
41 if (file) {
42 struct fdtable *fdt = files_fdtable(files);
43
44 f_flags = file->f_flags;
45 if (close_on_exec(fd, fdt))
46 f_flags |= O_CLOEXEC;
47
48 get_file(file);
49 ret = 0;
50 }
51 spin_unlock(&files->file_lock);
52 }
53 task_unlock(task);
54 put_task_struct(task);
55
56 if (ret)
57 return ret;
58
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);
63
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))
67 goto out;
68
69 if (file->f_op->show_fdinfo)
70 file->f_op->show_fdinfo(m, file);
71
72out:
73 fput(file);
74 return 0;
75}
76
77static int proc_fdinfo_access_allowed(struct inode *inode)
78{
79 bool allowed = false;
80 struct task_struct *task = get_proc_task(inode);
81
82 if (!task)
83 return -ESRCH;
84
85 allowed = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
86 put_task_struct(task);
87
88 if (!allowed)
89 return -EACCES;
90
91 return 0;
92}
93
94static int seq_fdinfo_open(struct inode *inode, struct file *file)
95{
96 int ret = proc_fdinfo_access_allowed(inode);
97
98 if (ret)
99 return ret;
100
101 return single_open(file, seq_show, inode);
102}
103
104static const struct file_operations proc_fdinfo_file_operations = {
105 .open = seq_fdinfo_open,
106 .read = seq_read,
107 .llseek = seq_lseek,
108 .release = single_release,
109};
110
111static bool tid_fd_mode(struct task_struct *task, unsigned fd, fmode_t *mode)
112{
113 struct file *file;
114
115 rcu_read_lock();
116 file = task_lookup_fdget_rcu(task, fd);
117 rcu_read_unlock();
118 if (file) {
119 *mode = file->f_mode;
120 fput(file);
121 }
122 return !!file;
123}
124
125static void tid_fd_update_inode(struct task_struct *task, struct inode *inode,
126 fmode_t f_mode)
127{
128 task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
129
130 if (S_ISLNK(inode->i_mode)) {
131 unsigned i_mode = S_IFLNK;
132 if (f_mode & FMODE_READ)
133 i_mode |= S_IRUSR | S_IXUSR;
134 if (f_mode & FMODE_WRITE)
135 i_mode |= S_IWUSR | S_IXUSR;
136 inode->i_mode = i_mode;
137 }
138 security_task_to_inode(task, inode);
139}
140
141static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
142{
143 struct task_struct *task;
144 struct inode *inode;
145 unsigned int fd;
146
147 if (flags & LOOKUP_RCU)
148 return -ECHILD;
149
150 inode = d_inode(dentry);
151 task = get_proc_task(inode);
152 fd = proc_fd(inode);
153
154 if (task) {
155 fmode_t f_mode;
156 if (tid_fd_mode(task, fd, &f_mode)) {
157 tid_fd_update_inode(task, inode, f_mode);
158 put_task_struct(task);
159 return 1;
160 }
161 put_task_struct(task);
162 }
163 return 0;
164}
165
166static const struct dentry_operations tid_fd_dentry_operations = {
167 .d_revalidate = tid_fd_revalidate,
168 .d_delete = pid_delete_dentry,
169};
170
171static int proc_fd_link(struct dentry *dentry, struct path *path)
172{
173 struct task_struct *task;
174 int ret = -ENOENT;
175
176 task = get_proc_task(d_inode(dentry));
177 if (task) {
178 unsigned int fd = proc_fd(d_inode(dentry));
179 struct file *fd_file;
180
181 fd_file = fget_task(task, fd);
182 if (fd_file) {
183 *path = fd_file->f_path;
184 path_get(&fd_file->f_path);
185 ret = 0;
186 fput(fd_file);
187 }
188 put_task_struct(task);
189 }
190
191 return ret;
192}
193
194struct fd_data {
195 fmode_t mode;
196 unsigned fd;
197};
198
199static struct dentry *proc_fd_instantiate(struct dentry *dentry,
200 struct task_struct *task, const void *ptr)
201{
202 const struct fd_data *data = ptr;
203 struct proc_inode *ei;
204 struct inode *inode;
205
206 inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK);
207 if (!inode)
208 return ERR_PTR(-ENOENT);
209
210 ei = PROC_I(inode);
211 ei->fd = data->fd;
212
213 inode->i_op = &proc_pid_link_inode_operations;
214 inode->i_size = 64;
215
216 ei->op.proc_get_link = proc_fd_link;
217 tid_fd_update_inode(task, inode, data->mode);
218
219 d_set_d_op(dentry, &tid_fd_dentry_operations);
220 return d_splice_alias(inode, dentry);
221}
222
223static struct dentry *proc_lookupfd_common(struct inode *dir,
224 struct dentry *dentry,
225 instantiate_t instantiate)
226{
227 struct task_struct *task = get_proc_task(dir);
228 struct fd_data data = {.fd = name_to_int(&dentry->d_name)};
229 struct dentry *result = ERR_PTR(-ENOENT);
230
231 if (!task)
232 goto out_no_task;
233 if (data.fd == ~0U)
234 goto out;
235 if (!tid_fd_mode(task, data.fd, &data.mode))
236 goto out;
237
238 result = instantiate(dentry, task, &data);
239out:
240 put_task_struct(task);
241out_no_task:
242 return result;
243}
244
245static int proc_readfd_common(struct file *file, struct dir_context *ctx,
246 instantiate_t instantiate)
247{
248 struct task_struct *p = get_proc_task(file_inode(file));
249 unsigned int fd;
250
251 if (!p)
252 return -ENOENT;
253
254 if (!dir_emit_dots(file, ctx))
255 goto out;
256
257 rcu_read_lock();
258 for (fd = ctx->pos - 2;; fd++) {
259 struct file *f;
260 struct fd_data data;
261 char name[10 + 1];
262 unsigned int len;
263
264 f = task_lookup_next_fdget_rcu(p, &fd);
265 ctx->pos = fd + 2LL;
266 if (!f)
267 break;
268 data.mode = f->f_mode;
269 rcu_read_unlock();
270 fput(f);
271 data.fd = fd;
272
273 len = snprintf(name, sizeof(name), "%u", fd);
274 if (!proc_fill_cache(file, ctx,
275 name, len, instantiate, p,
276 &data))
277 goto out;
278 cond_resched();
279 rcu_read_lock();
280 }
281 rcu_read_unlock();
282out:
283 put_task_struct(p);
284 return 0;
285}
286
287static int proc_readfd_count(struct inode *inode, loff_t *count)
288{
289 struct task_struct *p = get_proc_task(inode);
290 struct fdtable *fdt;
291
292 if (!p)
293 return -ENOENT;
294
295 task_lock(p);
296 if (p->files) {
297 rcu_read_lock();
298
299 fdt = files_fdtable(p->files);
300 *count = bitmap_weight(fdt->open_fds, fdt->max_fds);
301
302 rcu_read_unlock();
303 }
304 task_unlock(p);
305
306 put_task_struct(p);
307
308 return 0;
309}
310
311static int proc_readfd(struct file *file, struct dir_context *ctx)
312{
313 return proc_readfd_common(file, ctx, proc_fd_instantiate);
314}
315
316const struct file_operations proc_fd_operations = {
317 .read = generic_read_dir,
318 .iterate_shared = proc_readfd,
319 .llseek = generic_file_llseek,
320};
321
322static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
323 unsigned int flags)
324{
325 return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
326}
327
328/*
329 * /proc/pid/fd needs a special permission handler so that a process can still
330 * access /proc/self/fd after it has executed a setuid().
331 */
332int proc_fd_permission(struct mnt_idmap *idmap,
333 struct inode *inode, int mask)
334{
335 struct task_struct *p;
336 int rv;
337
338 rv = generic_permission(&nop_mnt_idmap, inode, mask);
339 if (rv == 0)
340 return rv;
341
342 rcu_read_lock();
343 p = pid_task(proc_pid(inode), PIDTYPE_PID);
344 if (p && same_thread_group(p, current))
345 rv = 0;
346 rcu_read_unlock();
347
348 return rv;
349}
350
351static int proc_fd_getattr(struct mnt_idmap *idmap,
352 const struct path *path, struct kstat *stat,
353 u32 request_mask, unsigned int query_flags)
354{
355 struct inode *inode = d_inode(path->dentry);
356 int rv = 0;
357
358 generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
359
360 /* If it's a directory, put the number of open fds there */
361 if (S_ISDIR(inode->i_mode)) {
362 rv = proc_readfd_count(inode, &stat->size);
363 if (rv < 0)
364 return rv;
365 }
366
367 return rv;
368}
369
370const struct inode_operations proc_fd_inode_operations = {
371 .lookup = proc_lookupfd,
372 .permission = proc_fd_permission,
373 .getattr = proc_fd_getattr,
374 .setattr = proc_setattr,
375};
376
377static struct dentry *proc_fdinfo_instantiate(struct dentry *dentry,
378 struct task_struct *task, const void *ptr)
379{
380 const struct fd_data *data = ptr;
381 struct proc_inode *ei;
382 struct inode *inode;
383
384 inode = proc_pid_make_inode(dentry->d_sb, task, S_IFREG | S_IRUGO);
385 if (!inode)
386 return ERR_PTR(-ENOENT);
387
388 ei = PROC_I(inode);
389 ei->fd = data->fd;
390
391 inode->i_fop = &proc_fdinfo_file_operations;
392 tid_fd_update_inode(task, inode, 0);
393
394 d_set_d_op(dentry, &tid_fd_dentry_operations);
395 return d_splice_alias(inode, dentry);
396}
397
398static struct dentry *
399proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags)
400{
401 return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
402}
403
404static int proc_readfdinfo(struct file *file, struct dir_context *ctx)
405{
406 return proc_readfd_common(file, ctx,
407 proc_fdinfo_instantiate);
408}
409
410static int proc_open_fdinfo(struct inode *inode, struct file *file)
411{
412 int ret = proc_fdinfo_access_allowed(inode);
413
414 if (ret)
415 return ret;
416
417 return 0;
418}
419
420const struct inode_operations proc_fdinfo_inode_operations = {
421 .lookup = proc_lookupfdinfo,
422 .setattr = proc_setattr,
423};
424
425const struct file_operations proc_fdinfo_operations = {
426 .open = proc_open_fdinfo,
427 .read = generic_read_dir,
428 .iterate_shared = proc_readfdinfo,
429 .llseek = generic_file_llseek,
430};