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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#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};