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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#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 f_flags = file->f_flags;
43 if (close_on_exec(fd, files))
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 dereferences 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 return single_open(file, seq_show, inode);
78}
79
80/*
81 * Shared /proc/pid/fdinfo and /proc/pid/fdinfo/fd permission helper to ensure
82 * that the current task has PTRACE_MODE_READ in addition to the normal
83 * POSIX-like checks.
84 */
85static int proc_fdinfo_permission(struct mnt_idmap *idmap, struct inode *inode,
86 int mask)
87{
88 bool allowed = false;
89 struct task_struct *task = get_proc_task(inode);
90
91 if (!task)
92 return -ESRCH;
93
94 allowed = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
95 put_task_struct(task);
96
97 if (!allowed)
98 return -EACCES;
99
100 return generic_permission(idmap, inode, mask);
101}
102
103static const struct inode_operations proc_fdinfo_file_inode_operations = {
104 .permission = proc_fdinfo_permission,
105 .setattr = proc_setattr,
106};
107
108static const struct file_operations proc_fdinfo_file_operations = {
109 .open = seq_fdinfo_open,
110 .read = seq_read,
111 .llseek = seq_lseek,
112 .release = single_release,
113};
114
115static bool tid_fd_mode(struct task_struct *task, unsigned fd, fmode_t *mode)
116{
117 struct file *file;
118
119 file = fget_task(task, fd);
120 if (file) {
121 *mode = file->f_mode;
122 fput(file);
123 }
124 return !!file;
125}
126
127static void tid_fd_update_inode(struct task_struct *task, struct inode *inode,
128 fmode_t f_mode)
129{
130 task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
131
132 if (S_ISLNK(inode->i_mode)) {
133 unsigned i_mode = S_IFLNK;
134 if (f_mode & FMODE_READ)
135 i_mode |= S_IRUSR | S_IXUSR;
136 if (f_mode & FMODE_WRITE)
137 i_mode |= S_IWUSR | S_IXUSR;
138 inode->i_mode = i_mode;
139 }
140 security_task_to_inode(task, inode);
141}
142
143static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
144{
145 struct task_struct *task;
146 struct inode *inode;
147 unsigned int fd;
148
149 if (flags & LOOKUP_RCU)
150 return -ECHILD;
151
152 inode = d_inode(dentry);
153 task = get_proc_task(inode);
154 fd = proc_fd(inode);
155
156 if (task) {
157 fmode_t f_mode;
158 if (tid_fd_mode(task, fd, &f_mode)) {
159 tid_fd_update_inode(task, inode, f_mode);
160 put_task_struct(task);
161 return 1;
162 }
163 put_task_struct(task);
164 }
165 return 0;
166}
167
168static const struct dentry_operations tid_fd_dentry_operations = {
169 .d_revalidate = tid_fd_revalidate,
170 .d_delete = pid_delete_dentry,
171};
172
173static int proc_fd_link(struct dentry *dentry, struct path *path)
174{
175 struct task_struct *task;
176 int ret = -ENOENT;
177
178 task = get_proc_task(d_inode(dentry));
179 if (task) {
180 unsigned int fd = proc_fd(d_inode(dentry));
181 struct file *fd_file;
182
183 fd_file = fget_task(task, fd);
184 if (fd_file) {
185 *path = fd_file->f_path;
186 path_get(&fd_file->f_path);
187 ret = 0;
188 fput(fd_file);
189 }
190 put_task_struct(task);
191 }
192
193 return ret;
194}
195
196struct fd_data {
197 fmode_t mode;
198 unsigned fd;
199};
200
201static struct dentry *proc_fd_instantiate(struct dentry *dentry,
202 struct task_struct *task, const void *ptr)
203{
204 const struct fd_data *data = ptr;
205 struct proc_inode *ei;
206 struct inode *inode;
207
208 inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK);
209 if (!inode)
210 return ERR_PTR(-ENOENT);
211
212 ei = PROC_I(inode);
213 ei->fd = data->fd;
214
215 inode->i_op = &proc_pid_link_inode_operations;
216 inode->i_size = 64;
217
218 ei->op.proc_get_link = proc_fd_link;
219 tid_fd_update_inode(task, inode, data->mode);
220
221 return proc_splice_unmountable(inode, dentry,
222 &tid_fd_dentry_operations);
223}
224
225static struct dentry *proc_lookupfd_common(struct inode *dir,
226 struct dentry *dentry,
227 instantiate_t instantiate)
228{
229 struct task_struct *task = get_proc_task(dir);
230 struct fd_data data = {.fd = name_to_int(&dentry->d_name)};
231 struct dentry *result = ERR_PTR(-ENOENT);
232
233 if (!task)
234 goto out_no_task;
235 if (data.fd == ~0U)
236 goto out;
237 if (!tid_fd_mode(task, data.fd, &data.mode))
238 goto out;
239
240 result = instantiate(dentry, task, &data);
241out:
242 put_task_struct(task);
243out_no_task:
244 return result;
245}
246
247static int proc_readfd_common(struct file *file, struct dir_context *ctx,
248 instantiate_t instantiate)
249{
250 struct task_struct *p = get_proc_task(file_inode(file));
251 unsigned int fd;
252
253 if (!p)
254 return -ENOENT;
255
256 if (!dir_emit_dots(file, ctx))
257 goto out;
258
259 for (fd = ctx->pos - 2;; fd++) {
260 struct file *f;
261 struct fd_data data;
262 char name[10 + 1];
263 unsigned int len;
264
265 f = fget_task_next(p, &fd);
266 ctx->pos = fd + 2LL;
267 if (!f)
268 break;
269 data.mode = f->f_mode;
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 break;
278 cond_resched();
279 }
280out:
281 put_task_struct(p);
282 return 0;
283}
284
285static int proc_readfd_count(struct inode *inode, loff_t *count)
286{
287 struct task_struct *p = get_proc_task(inode);
288 struct fdtable *fdt;
289
290 if (!p)
291 return -ENOENT;
292
293 task_lock(p);
294 if (p->files) {
295 rcu_read_lock();
296
297 fdt = files_fdtable(p->files);
298 *count = bitmap_weight(fdt->open_fds, fdt->max_fds);
299
300 rcu_read_unlock();
301 }
302 task_unlock(p);
303
304 put_task_struct(p);
305
306 return 0;
307}
308
309static int proc_fd_iterate(struct file *file, struct dir_context *ctx)
310{
311 return proc_readfd_common(file, ctx, proc_fd_instantiate);
312}
313
314const struct file_operations proc_fd_operations = {
315 .read = generic_read_dir,
316 .iterate_shared = proc_fd_iterate,
317 .llseek = generic_file_llseek,
318};
319
320static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
321 unsigned int flags)
322{
323 return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
324}
325
326/*
327 * /proc/pid/fd needs a special permission handler so that a process can still
328 * access /proc/self/fd after it has executed a setuid().
329 */
330int proc_fd_permission(struct mnt_idmap *idmap,
331 struct inode *inode, int mask)
332{
333 struct task_struct *p;
334 int rv;
335
336 rv = generic_permission(&nop_mnt_idmap, inode, mask);
337 if (rv == 0)
338 return rv;
339
340 rcu_read_lock();
341 p = pid_task(proc_pid(inode), PIDTYPE_PID);
342 if (p && same_thread_group(p, current))
343 rv = 0;
344 rcu_read_unlock();
345
346 return rv;
347}
348
349static int proc_fd_getattr(struct mnt_idmap *idmap,
350 const struct path *path, struct kstat *stat,
351 u32 request_mask, unsigned int query_flags)
352{
353 struct inode *inode = d_inode(path->dentry);
354 int rv = 0;
355
356 generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
357
358 /* If it's a directory, put the number of open fds there */
359 if (S_ISDIR(inode->i_mode)) {
360 rv = proc_readfd_count(inode, &stat->size);
361 if (rv < 0)
362 return rv;
363 }
364
365 return rv;
366}
367
368const struct inode_operations proc_fd_inode_operations = {
369 .lookup = proc_lookupfd,
370 .permission = proc_fd_permission,
371 .getattr = proc_fd_getattr,
372 .setattr = proc_setattr,
373};
374
375static struct dentry *proc_fdinfo_instantiate(struct dentry *dentry,
376 struct task_struct *task, const void *ptr)
377{
378 const struct fd_data *data = ptr;
379 struct proc_inode *ei;
380 struct inode *inode;
381
382 inode = proc_pid_make_inode(dentry->d_sb, task, S_IFREG | S_IRUGO);
383 if (!inode)
384 return ERR_PTR(-ENOENT);
385
386 ei = PROC_I(inode);
387 ei->fd = data->fd;
388
389 inode->i_op = &proc_fdinfo_file_inode_operations;
390
391 inode->i_fop = &proc_fdinfo_file_operations;
392 tid_fd_update_inode(task, inode, 0);
393
394 return proc_splice_unmountable(inode, dentry,
395 &tid_fd_dentry_operations);
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_fdinfo_iterate(struct file *file, struct dir_context *ctx)
405{
406 return proc_readfd_common(file, ctx,
407 proc_fdinfo_instantiate);
408}
409
410const struct inode_operations proc_fdinfo_inode_operations = {
411 .lookup = proc_lookupfdinfo,
412 .permission = proc_fdinfo_permission,
413 .setattr = proc_setattr,
414};
415
416const struct file_operations proc_fdinfo_operations = {
417 .read = generic_read_dir,
418 .iterate_shared = proc_fdinfo_iterate,
419 .llseek = generic_file_llseek,
420};
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};