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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/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
16#include <linux/proc_fs.h>
17
18#include "../mount.h"
19#include "internal.h"
20#include "fd.h"
21
22static int seq_show(struct seq_file *m, void *v)
23{
24 struct files_struct *files = NULL;
25 int f_flags = 0, ret = -ENOENT;
26 struct file *file = NULL;
27 struct task_struct *task;
28
29 task = get_proc_task(m->private);
30 if (!task)
31 return -ENOENT;
32
33 task_lock(task);
34 files = task->files;
35 if (files) {
36 unsigned int fd = proc_fd(m->private);
37
38 spin_lock(&files->file_lock);
39 file = files_lookup_fd_locked(files, fd);
40 if (file) {
41 struct fdtable *fdt = files_fdtable(files);
42
43 f_flags = file->f_flags;
44 if (close_on_exec(fd, fdt))
45 f_flags |= O_CLOEXEC;
46
47 get_file(file);
48 ret = 0;
49 }
50 spin_unlock(&files->file_lock);
51 }
52 task_unlock(task);
53 put_task_struct(task);
54
55 if (ret)
56 return ret;
57
58 seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\nino:\t%lu\n",
59 (long long)file->f_pos, f_flags,
60 real_mount(file->f_path.mnt)->mnt_id,
61 file_inode(file)->i_ino);
62
63 /* show_fd_locks() never deferences files so a stale value is safe */
64 show_fd_locks(m, file, files);
65 if (seq_has_overflowed(m))
66 goto out;
67
68 if (file->f_op->show_fdinfo)
69 file->f_op->show_fdinfo(m, file);
70
71out:
72 fput(file);
73 return 0;
74}
75
76static int proc_fdinfo_access_allowed(struct inode *inode)
77{
78 bool allowed = false;
79 struct task_struct *task = get_proc_task(inode);
80
81 if (!task)
82 return -ESRCH;
83
84 allowed = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
85 put_task_struct(task);
86
87 if (!allowed)
88 return -EACCES;
89
90 return 0;
91}
92
93static int seq_fdinfo_open(struct inode *inode, struct file *file)
94{
95 int ret = proc_fdinfo_access_allowed(inode);
96
97 if (ret)
98 return ret;
99
100 return single_open(file, seq_show, inode);
101}
102
103static const struct file_operations proc_fdinfo_file_operations = {
104 .open = seq_fdinfo_open,
105 .read = seq_read,
106 .llseek = seq_lseek,
107 .release = single_release,
108};
109
110static bool tid_fd_mode(struct task_struct *task, unsigned fd, fmode_t *mode)
111{
112 struct file *file;
113
114 rcu_read_lock();
115 file = task_lookup_fd_rcu(task, fd);
116 if (file)
117 *mode = file->f_mode;
118 rcu_read_unlock();
119 return !!file;
120}
121
122static void tid_fd_update_inode(struct task_struct *task, struct inode *inode,
123 fmode_t f_mode)
124{
125 task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
126
127 if (S_ISLNK(inode->i_mode)) {
128 unsigned i_mode = S_IFLNK;
129 if (f_mode & FMODE_READ)
130 i_mode |= S_IRUSR | S_IXUSR;
131 if (f_mode & FMODE_WRITE)
132 i_mode |= S_IWUSR | S_IXUSR;
133 inode->i_mode = i_mode;
134 }
135 security_task_to_inode(task, inode);
136}
137
138static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
139{
140 struct task_struct *task;
141 struct inode *inode;
142 unsigned int fd;
143
144 if (flags & LOOKUP_RCU)
145 return -ECHILD;
146
147 inode = d_inode(dentry);
148 task = get_proc_task(inode);
149 fd = proc_fd(inode);
150
151 if (task) {
152 fmode_t f_mode;
153 if (tid_fd_mode(task, fd, &f_mode)) {
154 tid_fd_update_inode(task, inode, f_mode);
155 put_task_struct(task);
156 return 1;
157 }
158 put_task_struct(task);
159 }
160 return 0;
161}
162
163static const struct dentry_operations tid_fd_dentry_operations = {
164 .d_revalidate = tid_fd_revalidate,
165 .d_delete = pid_delete_dentry,
166};
167
168static int proc_fd_link(struct dentry *dentry, struct path *path)
169{
170 struct task_struct *task;
171 int ret = -ENOENT;
172
173 task = get_proc_task(d_inode(dentry));
174 if (task) {
175 unsigned int fd = proc_fd(d_inode(dentry));
176 struct file *fd_file;
177
178 fd_file = fget_task(task, fd);
179 if (fd_file) {
180 *path = fd_file->f_path;
181 path_get(&fd_file->f_path);
182 ret = 0;
183 fput(fd_file);
184 }
185 put_task_struct(task);
186 }
187
188 return ret;
189}
190
191struct fd_data {
192 fmode_t mode;
193 unsigned fd;
194};
195
196static struct dentry *proc_fd_instantiate(struct dentry *dentry,
197 struct task_struct *task, const void *ptr)
198{
199 const struct fd_data *data = ptr;
200 struct proc_inode *ei;
201 struct inode *inode;
202
203 inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK);
204 if (!inode)
205 return ERR_PTR(-ENOENT);
206
207 ei = PROC_I(inode);
208 ei->fd = data->fd;
209
210 inode->i_op = &proc_pid_link_inode_operations;
211 inode->i_size = 64;
212
213 ei->op.proc_get_link = proc_fd_link;
214 tid_fd_update_inode(task, inode, data->mode);
215
216 d_set_d_op(dentry, &tid_fd_dentry_operations);
217 return d_splice_alias(inode, dentry);
218}
219
220static struct dentry *proc_lookupfd_common(struct inode *dir,
221 struct dentry *dentry,
222 instantiate_t instantiate)
223{
224 struct task_struct *task = get_proc_task(dir);
225 struct fd_data data = {.fd = name_to_int(&dentry->d_name)};
226 struct dentry *result = ERR_PTR(-ENOENT);
227
228 if (!task)
229 goto out_no_task;
230 if (data.fd == ~0U)
231 goto out;
232 if (!tid_fd_mode(task, data.fd, &data.mode))
233 goto out;
234
235 result = instantiate(dentry, task, &data);
236out:
237 put_task_struct(task);
238out_no_task:
239 return result;
240}
241
242static int proc_readfd_common(struct file *file, struct dir_context *ctx,
243 instantiate_t instantiate)
244{
245 struct task_struct *p = get_proc_task(file_inode(file));
246 unsigned int fd;
247
248 if (!p)
249 return -ENOENT;
250
251 if (!dir_emit_dots(file, ctx))
252 goto out;
253
254 rcu_read_lock();
255 for (fd = ctx->pos - 2;; fd++) {
256 struct file *f;
257 struct fd_data data;
258 char name[10 + 1];
259 unsigned int len;
260
261 f = task_lookup_next_fd_rcu(p, &fd);
262 ctx->pos = fd + 2LL;
263 if (!f)
264 break;
265 data.mode = f->f_mode;
266 rcu_read_unlock();
267 data.fd = fd;
268
269 len = snprintf(name, sizeof(name), "%u", fd);
270 if (!proc_fill_cache(file, ctx,
271 name, len, instantiate, p,
272 &data))
273 goto out;
274 cond_resched();
275 rcu_read_lock();
276 }
277 rcu_read_unlock();
278out:
279 put_task_struct(p);
280 return 0;
281}
282
283static int proc_readfd_count(struct inode *inode, loff_t *count)
284{
285 struct task_struct *p = get_proc_task(inode);
286 struct fdtable *fdt;
287
288 if (!p)
289 return -ENOENT;
290
291 task_lock(p);
292 if (p->files) {
293 rcu_read_lock();
294
295 fdt = files_fdtable(p->files);
296 *count = bitmap_weight(fdt->open_fds, fdt->max_fds);
297
298 rcu_read_unlock();
299 }
300 task_unlock(p);
301
302 put_task_struct(p);
303
304 return 0;
305}
306
307static int proc_readfd(struct file *file, struct dir_context *ctx)
308{
309 return proc_readfd_common(file, ctx, proc_fd_instantiate);
310}
311
312const struct file_operations proc_fd_operations = {
313 .read = generic_read_dir,
314 .iterate_shared = proc_readfd,
315 .llseek = generic_file_llseek,
316};
317
318static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
319 unsigned int flags)
320{
321 return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
322}
323
324/*
325 * /proc/pid/fd needs a special permission handler so that a process can still
326 * access /proc/self/fd after it has executed a setuid().
327 */
328int proc_fd_permission(struct user_namespace *mnt_userns,
329 struct inode *inode, int mask)
330{
331 struct task_struct *p;
332 int rv;
333
334 rv = generic_permission(&init_user_ns, inode, mask);
335 if (rv == 0)
336 return rv;
337
338 rcu_read_lock();
339 p = pid_task(proc_pid(inode), PIDTYPE_PID);
340 if (p && same_thread_group(p, current))
341 rv = 0;
342 rcu_read_unlock();
343
344 return rv;
345}
346
347static int proc_fd_getattr(struct user_namespace *mnt_userns,
348 const struct path *path, struct kstat *stat,
349 u32 request_mask, unsigned int query_flags)
350{
351 struct inode *inode = d_inode(path->dentry);
352 int rv = 0;
353
354 generic_fillattr(&init_user_ns, inode, stat);
355
356 /* If it's a directory, put the number of open fds there */
357 if (S_ISDIR(inode->i_mode)) {
358 rv = proc_readfd_count(inode, &stat->size);
359 if (rv < 0)
360 return rv;
361 }
362
363 return rv;
364}
365
366const struct inode_operations proc_fd_inode_operations = {
367 .lookup = proc_lookupfd,
368 .permission = proc_fd_permission,
369 .getattr = proc_fd_getattr,
370 .setattr = proc_setattr,
371};
372
373static struct dentry *proc_fdinfo_instantiate(struct dentry *dentry,
374 struct task_struct *task, const void *ptr)
375{
376 const struct fd_data *data = ptr;
377 struct proc_inode *ei;
378 struct inode *inode;
379
380 inode = proc_pid_make_inode(dentry->d_sb, task, S_IFREG | S_IRUGO);
381 if (!inode)
382 return ERR_PTR(-ENOENT);
383
384 ei = PROC_I(inode);
385 ei->fd = data->fd;
386
387 inode->i_fop = &proc_fdinfo_file_operations;
388 tid_fd_update_inode(task, inode, 0);
389
390 d_set_d_op(dentry, &tid_fd_dentry_operations);
391 return d_splice_alias(inode, dentry);
392}
393
394static struct dentry *
395proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags)
396{
397 return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
398}
399
400static int proc_readfdinfo(struct file *file, struct dir_context *ctx)
401{
402 return proc_readfd_common(file, ctx,
403 proc_fdinfo_instantiate);
404}
405
406static int proc_open_fdinfo(struct inode *inode, struct file *file)
407{
408 int ret = proc_fdinfo_access_allowed(inode);
409
410 if (ret)
411 return ret;
412
413 return 0;
414}
415
416const struct inode_operations proc_fdinfo_inode_operations = {
417 .lookup = proc_lookupfdinfo,
418 .setattr = proc_setattr,
419};
420
421const struct file_operations proc_fdinfo_operations = {
422 .open = proc_open_fdinfo,
423 .read = generic_read_dir,
424 .iterate_shared = proc_readfdinfo,
425 .llseek = generic_file_llseek,
426};
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};