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1#include <linux/sched.h>
2#include <linux/errno.h>
3#include <linux/dcache.h>
4#include <linux/path.h>
5#include <linux/fdtable.h>
6#include <linux/namei.h>
7#include <linux/pid.h>
8#include <linux/security.h>
9#include <linux/file.h>
10#include <linux/seq_file.h>
11
12#include <linux/proc_fs.h>
13
14#include "../mount.h"
15#include "internal.h"
16#include "fd.h"
17
18static int seq_show(struct seq_file *m, void *v)
19{
20 struct files_struct *files = NULL;
21 int f_flags = 0, ret = -ENOENT;
22 struct file *file = NULL;
23 struct task_struct *task;
24
25 task = get_proc_task(m->private);
26 if (!task)
27 return -ENOENT;
28
29 files = get_files_struct(task);
30 put_task_struct(task);
31
32 if (files) {
33 int fd = proc_fd(m->private);
34
35 spin_lock(&files->file_lock);
36 file = fcheck_files(files, fd);
37 if (file) {
38 struct fdtable *fdt = files_fdtable(files);
39
40 f_flags = file->f_flags;
41 if (close_on_exec(fd, fdt))
42 f_flags |= O_CLOEXEC;
43
44 get_file(file);
45 ret = 0;
46 }
47 spin_unlock(&files->file_lock);
48 put_files_struct(files);
49 }
50
51 if (!ret) {
52 seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\n",
53 (long long)file->f_pos, f_flags,
54 real_mount(file->f_path.mnt)->mnt_id);
55 if (file->f_op->show_fdinfo)
56 ret = file->f_op->show_fdinfo(m, file);
57 fput(file);
58 }
59
60 return ret;
61}
62
63static int seq_fdinfo_open(struct inode *inode, struct file *file)
64{
65 return single_open(file, seq_show, inode);
66}
67
68static const struct file_operations proc_fdinfo_file_operations = {
69 .open = seq_fdinfo_open,
70 .read = seq_read,
71 .llseek = seq_lseek,
72 .release = single_release,
73};
74
75static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
76{
77 struct files_struct *files;
78 struct task_struct *task;
79 const struct cred *cred;
80 struct inode *inode;
81 int fd;
82
83 if (flags & LOOKUP_RCU)
84 return -ECHILD;
85
86 inode = dentry->d_inode;
87 task = get_proc_task(inode);
88 fd = proc_fd(inode);
89
90 if (task) {
91 files = get_files_struct(task);
92 if (files) {
93 struct file *file;
94
95 rcu_read_lock();
96 file = fcheck_files(files, fd);
97 if (file) {
98 unsigned f_mode = file->f_mode;
99
100 rcu_read_unlock();
101 put_files_struct(files);
102
103 if (task_dumpable(task)) {
104 rcu_read_lock();
105 cred = __task_cred(task);
106 inode->i_uid = cred->euid;
107 inode->i_gid = cred->egid;
108 rcu_read_unlock();
109 } else {
110 inode->i_uid = GLOBAL_ROOT_UID;
111 inode->i_gid = GLOBAL_ROOT_GID;
112 }
113
114 if (S_ISLNK(inode->i_mode)) {
115 unsigned i_mode = S_IFLNK;
116 if (f_mode & FMODE_READ)
117 i_mode |= S_IRUSR | S_IXUSR;
118 if (f_mode & FMODE_WRITE)
119 i_mode |= S_IWUSR | S_IXUSR;
120 inode->i_mode = i_mode;
121 }
122
123 security_task_to_inode(task, inode);
124 put_task_struct(task);
125 return 1;
126 }
127 rcu_read_unlock();
128 put_files_struct(files);
129 }
130 put_task_struct(task);
131 }
132
133 d_drop(dentry);
134 return 0;
135}
136
137static const struct dentry_operations tid_fd_dentry_operations = {
138 .d_revalidate = tid_fd_revalidate,
139 .d_delete = pid_delete_dentry,
140};
141
142static int proc_fd_link(struct dentry *dentry, struct path *path)
143{
144 struct files_struct *files = NULL;
145 struct task_struct *task;
146 int ret = -ENOENT;
147
148 task = get_proc_task(dentry->d_inode);
149 if (task) {
150 files = get_files_struct(task);
151 put_task_struct(task);
152 }
153
154 if (files) {
155 int fd = proc_fd(dentry->d_inode);
156 struct file *fd_file;
157
158 spin_lock(&files->file_lock);
159 fd_file = fcheck_files(files, fd);
160 if (fd_file) {
161 *path = fd_file->f_path;
162 path_get(&fd_file->f_path);
163 ret = 0;
164 }
165 spin_unlock(&files->file_lock);
166 put_files_struct(files);
167 }
168
169 return ret;
170}
171
172static int
173proc_fd_instantiate(struct inode *dir, struct dentry *dentry,
174 struct task_struct *task, const void *ptr)
175{
176 unsigned fd = (unsigned long)ptr;
177 struct proc_inode *ei;
178 struct inode *inode;
179
180 inode = proc_pid_make_inode(dir->i_sb, task);
181 if (!inode)
182 goto out;
183
184 ei = PROC_I(inode);
185 ei->fd = fd;
186
187 inode->i_mode = S_IFLNK;
188 inode->i_op = &proc_pid_link_inode_operations;
189 inode->i_size = 64;
190
191 ei->op.proc_get_link = proc_fd_link;
192
193 d_set_d_op(dentry, &tid_fd_dentry_operations);
194 d_add(dentry, inode);
195
196 /* Close the race of the process dying before we return the dentry */
197 if (tid_fd_revalidate(dentry, 0))
198 return 0;
199 out:
200 return -ENOENT;
201}
202
203static struct dentry *proc_lookupfd_common(struct inode *dir,
204 struct dentry *dentry,
205 instantiate_t instantiate)
206{
207 struct task_struct *task = get_proc_task(dir);
208 int result = -ENOENT;
209 unsigned fd = name_to_int(dentry);
210
211 if (!task)
212 goto out_no_task;
213 if (fd == ~0U)
214 goto out;
215
216 result = instantiate(dir, dentry, task, (void *)(unsigned long)fd);
217out:
218 put_task_struct(task);
219out_no_task:
220 return ERR_PTR(result);
221}
222
223static int proc_readfd_common(struct file *file, struct dir_context *ctx,
224 instantiate_t instantiate)
225{
226 struct task_struct *p = get_proc_task(file_inode(file));
227 struct files_struct *files;
228 unsigned int fd;
229
230 if (!p)
231 return -ENOENT;
232
233 if (!dir_emit_dots(file, ctx))
234 goto out;
235 files = get_files_struct(p);
236 if (!files)
237 goto out;
238
239 rcu_read_lock();
240 for (fd = ctx->pos - 2;
241 fd < files_fdtable(files)->max_fds;
242 fd++, ctx->pos++) {
243 char name[PROC_NUMBUF];
244 int len;
245
246 if (!fcheck_files(files, fd))
247 continue;
248 rcu_read_unlock();
249
250 len = snprintf(name, sizeof(name), "%d", fd);
251 if (!proc_fill_cache(file, ctx,
252 name, len, instantiate, p,
253 (void *)(unsigned long)fd))
254 goto out_fd_loop;
255 rcu_read_lock();
256 }
257 rcu_read_unlock();
258out_fd_loop:
259 put_files_struct(files);
260out:
261 put_task_struct(p);
262 return 0;
263}
264
265static int proc_readfd(struct file *file, struct dir_context *ctx)
266{
267 return proc_readfd_common(file, ctx, proc_fd_instantiate);
268}
269
270const struct file_operations proc_fd_operations = {
271 .read = generic_read_dir,
272 .iterate = proc_readfd,
273 .llseek = default_llseek,
274};
275
276static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
277 unsigned int flags)
278{
279 return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
280}
281
282/*
283 * /proc/pid/fd needs a special permission handler so that a process can still
284 * access /proc/self/fd after it has executed a setuid().
285 */
286int proc_fd_permission(struct inode *inode, int mask)
287{
288 int rv = generic_permission(inode, mask);
289 if (rv == 0)
290 return 0;
291 if (task_tgid(current) == proc_pid(inode))
292 rv = 0;
293 return rv;
294}
295
296const struct inode_operations proc_fd_inode_operations = {
297 .lookup = proc_lookupfd,
298 .permission = proc_fd_permission,
299 .setattr = proc_setattr,
300};
301
302static int
303proc_fdinfo_instantiate(struct inode *dir, struct dentry *dentry,
304 struct task_struct *task, const void *ptr)
305{
306 unsigned fd = (unsigned long)ptr;
307 struct proc_inode *ei;
308 struct inode *inode;
309
310 inode = proc_pid_make_inode(dir->i_sb, task);
311 if (!inode)
312 goto out;
313
314 ei = PROC_I(inode);
315 ei->fd = fd;
316
317 inode->i_mode = S_IFREG | S_IRUSR;
318 inode->i_fop = &proc_fdinfo_file_operations;
319
320 d_set_d_op(dentry, &tid_fd_dentry_operations);
321 d_add(dentry, inode);
322
323 /* Close the race of the process dying before we return the dentry */
324 if (tid_fd_revalidate(dentry, 0))
325 return 0;
326 out:
327 return -ENOENT;
328}
329
330static struct dentry *
331proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags)
332{
333 return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
334}
335
336static int proc_readfdinfo(struct file *file, struct dir_context *ctx)
337{
338 return proc_readfd_common(file, ctx,
339 proc_fdinfo_instantiate);
340}
341
342const struct inode_operations proc_fdinfo_inode_operations = {
343 .lookup = proc_lookupfdinfo,
344 .setattr = proc_setattr,
345};
346
347const struct file_operations proc_fdinfo_operations = {
348 .read = generic_read_dir,
349 .iterate = proc_readfdinfo,
350 .llseek = default_llseek,
351};
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};