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 #include <linux/fs.h>
12
13 #include <linux/proc_fs.h>
14
15 #include "../mount.h"
16 #include "internal.h"
17 #include "fd.h"
18
seq_show(struct seq_file * m,void * v)19 static int seq_show(struct seq_file *m, void *v)
20 {
21 struct files_struct *files = NULL;
22 int f_flags = 0, ret = -ENOENT;
23 struct file *file = NULL;
24 struct task_struct *task;
25
26 task = get_proc_task(m->private);
27 if (!task)
28 return -ENOENT;
29
30 files = get_files_struct(task);
31 put_task_struct(task);
32
33 if (files) {
34 unsigned int fd = proc_fd(m->private);
35
36 spin_lock(&files->file_lock);
37 file = fcheck_files(files, fd);
38 if (file) {
39 struct fdtable *fdt = files_fdtable(files);
40
41 f_flags = file->f_flags;
42 if (close_on_exec(fd, fdt))
43 f_flags |= O_CLOEXEC;
44
45 get_file(file);
46 ret = 0;
47 }
48 spin_unlock(&files->file_lock);
49 put_files_struct(files);
50 }
51
52 if (ret)
53 return ret;
54
55 seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\n",
56 (long long)file->f_pos, f_flags,
57 real_mount(file->f_path.mnt)->mnt_id);
58
59 show_fd_locks(m, file, files);
60 if (seq_has_overflowed(m))
61 goto out;
62
63 if (file->f_op->show_fdinfo)
64 file->f_op->show_fdinfo(m, file);
65
66 out:
67 fput(file);
68 return 0;
69 }
70
seq_fdinfo_open(struct inode * inode,struct file * file)71 static int seq_fdinfo_open(struct inode *inode, struct file *file)
72 {
73 return single_open(file, seq_show, inode);
74 }
75
76 static const struct file_operations proc_fdinfo_file_operations = {
77 .open = seq_fdinfo_open,
78 .read = seq_read,
79 .llseek = seq_lseek,
80 .release = single_release,
81 };
82
tid_fd_revalidate(struct dentry * dentry,unsigned int flags)83 static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
84 {
85 struct files_struct *files;
86 struct task_struct *task;
87 const struct cred *cred;
88 struct inode *inode;
89 unsigned int fd;
90
91 if (flags & LOOKUP_RCU)
92 return -ECHILD;
93
94 inode = d_inode(dentry);
95 task = get_proc_task(inode);
96 fd = proc_fd(inode);
97
98 if (task) {
99 files = get_files_struct(task);
100 if (files) {
101 struct file *file;
102
103 rcu_read_lock();
104 file = fcheck_files(files, fd);
105 if (file) {
106 unsigned f_mode = file->f_mode;
107
108 rcu_read_unlock();
109 put_files_struct(files);
110
111 if (task_dumpable(task)) {
112 rcu_read_lock();
113 cred = __task_cred(task);
114 inode->i_uid = cred->euid;
115 inode->i_gid = cred->egid;
116 rcu_read_unlock();
117 } else {
118 inode->i_uid = GLOBAL_ROOT_UID;
119 inode->i_gid = GLOBAL_ROOT_GID;
120 }
121
122 if (S_ISLNK(inode->i_mode)) {
123 unsigned i_mode = S_IFLNK;
124 if (f_mode & FMODE_READ)
125 i_mode |= S_IRUSR | S_IXUSR;
126 if (f_mode & FMODE_WRITE)
127 i_mode |= S_IWUSR | S_IXUSR;
128 inode->i_mode = i_mode;
129 }
130
131 security_task_to_inode(task, inode);
132 put_task_struct(task);
133 return 1;
134 }
135 rcu_read_unlock();
136 put_files_struct(files);
137 }
138 put_task_struct(task);
139 }
140 return 0;
141 }
142
143 static const struct dentry_operations tid_fd_dentry_operations = {
144 .d_revalidate = tid_fd_revalidate,
145 .d_delete = pid_delete_dentry,
146 };
147
proc_fd_link(struct dentry * dentry,struct path * path)148 static int proc_fd_link(struct dentry *dentry, struct path *path)
149 {
150 struct files_struct *files = NULL;
151 struct task_struct *task;
152 int ret = -ENOENT;
153
154 task = get_proc_task(d_inode(dentry));
155 if (task) {
156 files = get_files_struct(task);
157 put_task_struct(task);
158 }
159
160 if (files) {
161 unsigned int fd = proc_fd(d_inode(dentry));
162 struct file *fd_file;
163
164 spin_lock(&files->file_lock);
165 fd_file = fcheck_files(files, fd);
166 if (fd_file) {
167 *path = fd_file->f_path;
168 path_get(&fd_file->f_path);
169 ret = 0;
170 }
171 spin_unlock(&files->file_lock);
172 put_files_struct(files);
173 }
174
175 return ret;
176 }
177
178 static int
proc_fd_instantiate(struct inode * dir,struct dentry * dentry,struct task_struct * task,const void * ptr)179 proc_fd_instantiate(struct inode *dir, struct dentry *dentry,
180 struct task_struct *task, const void *ptr)
181 {
182 unsigned fd = (unsigned long)ptr;
183 struct proc_inode *ei;
184 struct inode *inode;
185
186 inode = proc_pid_make_inode(dir->i_sb, task);
187 if (!inode)
188 goto out;
189
190 ei = PROC_I(inode);
191 ei->fd = fd;
192
193 inode->i_mode = S_IFLNK;
194 inode->i_op = &proc_pid_link_inode_operations;
195 inode->i_size = 64;
196
197 ei->op.proc_get_link = proc_fd_link;
198
199 d_set_d_op(dentry, &tid_fd_dentry_operations);
200 d_add(dentry, inode);
201
202 /* Close the race of the process dying before we return the dentry */
203 if (tid_fd_revalidate(dentry, 0))
204 return 0;
205 out:
206 return -ENOENT;
207 }
208
proc_lookupfd_common(struct inode * dir,struct dentry * dentry,instantiate_t instantiate)209 static 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 int result = -ENOENT;
215 unsigned fd = name_to_int(&dentry->d_name);
216
217 if (!task)
218 goto out_no_task;
219 if (fd == ~0U)
220 goto out;
221
222 result = instantiate(dir, dentry, task, (void *)(unsigned long)fd);
223 out:
224 put_task_struct(task);
225 out_no_task:
226 return ERR_PTR(result);
227 }
228
proc_readfd_common(struct file * file,struct dir_context * ctx,instantiate_t instantiate)229 static int proc_readfd_common(struct file *file, struct dir_context *ctx,
230 instantiate_t instantiate)
231 {
232 struct task_struct *p = get_proc_task(file_inode(file));
233 struct files_struct *files;
234 unsigned int fd;
235
236 if (!p)
237 return -ENOENT;
238
239 if (!dir_emit_dots(file, ctx))
240 goto out;
241 files = get_files_struct(p);
242 if (!files)
243 goto out;
244
245 rcu_read_lock();
246 for (fd = ctx->pos - 2;
247 fd < files_fdtable(files)->max_fds;
248 fd++, ctx->pos++) {
249 char name[PROC_NUMBUF];
250 int len;
251
252 if (!fcheck_files(files, fd))
253 continue;
254 rcu_read_unlock();
255
256 len = snprintf(name, sizeof(name), "%u", fd);
257 if (!proc_fill_cache(file, ctx,
258 name, len, instantiate, p,
259 (void *)(unsigned long)fd))
260 goto out_fd_loop;
261 cond_resched();
262 rcu_read_lock();
263 }
264 rcu_read_unlock();
265 out_fd_loop:
266 put_files_struct(files);
267 out:
268 put_task_struct(p);
269 return 0;
270 }
271
proc_readfd(struct file * file,struct dir_context * ctx)272 static int proc_readfd(struct file *file, struct dir_context *ctx)
273 {
274 return proc_readfd_common(file, ctx, proc_fd_instantiate);
275 }
276
277 const struct file_operations proc_fd_operations = {
278 .read = generic_read_dir,
279 .iterate_shared = proc_readfd,
280 .llseek = generic_file_llseek,
281 };
282
proc_lookupfd(struct inode * dir,struct dentry * dentry,unsigned int flags)283 static 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 */
proc_fd_permission(struct inode * inode,int mask)293 int proc_fd_permission(struct inode *inode, int mask)
294 {
295 struct task_struct *p;
296 int rv;
297
298 rv = generic_permission(inode, mask);
299 if (rv == 0)
300 return rv;
301
302 rcu_read_lock();
303 p = pid_task(proc_pid(inode), PIDTYPE_PID);
304 if (p && same_thread_group(p, current))
305 rv = 0;
306 rcu_read_unlock();
307
308 return rv;
309 }
310
311 const struct inode_operations proc_fd_inode_operations = {
312 .lookup = proc_lookupfd,
313 .permission = proc_fd_permission,
314 .setattr = proc_setattr,
315 };
316
317 static int
proc_fdinfo_instantiate(struct inode * dir,struct dentry * dentry,struct task_struct * task,const void * ptr)318 proc_fdinfo_instantiate(struct inode *dir, struct dentry *dentry,
319 struct task_struct *task, const void *ptr)
320 {
321 unsigned fd = (unsigned long)ptr;
322 struct proc_inode *ei;
323 struct inode *inode;
324
325 inode = proc_pid_make_inode(dir->i_sb, task);
326 if (!inode)
327 goto out;
328
329 ei = PROC_I(inode);
330 ei->fd = fd;
331
332 inode->i_mode = S_IFREG | S_IRUSR;
333 inode->i_fop = &proc_fdinfo_file_operations;
334
335 d_set_d_op(dentry, &tid_fd_dentry_operations);
336 d_add(dentry, inode);
337
338 /* Close the race of the process dying before we return the dentry */
339 if (tid_fd_revalidate(dentry, 0))
340 return 0;
341 out:
342 return -ENOENT;
343 }
344
345 static struct dentry *
proc_lookupfdinfo(struct inode * dir,struct dentry * dentry,unsigned int flags)346 proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags)
347 {
348 return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
349 }
350
proc_readfdinfo(struct file * file,struct dir_context * ctx)351 static int proc_readfdinfo(struct file *file, struct dir_context *ctx)
352 {
353 return proc_readfd_common(file, ctx,
354 proc_fdinfo_instantiate);
355 }
356
357 const struct inode_operations proc_fdinfo_inode_operations = {
358 .lookup = proc_lookupfdinfo,
359 .setattr = proc_setattr,
360 };
361
362 const struct file_operations proc_fdinfo_operations = {
363 .read = generic_read_dir,
364 .iterate_shared = proc_readfdinfo,
365 .llseek = generic_file_llseek,
366 };
367