Loading...
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#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};