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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
3f07c014 | 2 | #include <linux/sched/signal.h> |
faf60af1 CG |
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> | |
ddd3e077 CG |
10 | #include <linux/file.h> |
11 | #include <linux/seq_file.h> | |
6c8c9031 | 12 | #include <linux/fs.h> |
faf60af1 CG |
13 | |
14 | #include <linux/proc_fs.h> | |
15 | ||
49d063cb | 16 | #include "../mount.h" |
faf60af1 CG |
17 | #include "internal.h" |
18 | #include "fd.h" | |
19 | ||
ddd3e077 | 20 | static int seq_show(struct seq_file *m, void *v) |
faf60af1 | 21 | { |
faf60af1 | 22 | struct files_struct *files = NULL; |
ddd3e077 CG |
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 | ||
775e0656 EB |
31 | task_lock(task); |
32 | files = task->files; | |
faf60af1 | 33 | if (files) { |
771187d6 | 34 | unsigned int fd = proc_fd(m->private); |
ddd3e077 | 35 | |
faf60af1 | 36 | spin_lock(&files->file_lock); |
120ce2b0 | 37 | file = files_lookup_fd_locked(files, fd); |
faf60af1 | 38 | if (file) { |
ddd3e077 | 39 | struct fdtable *fdt = files_fdtable(files); |
faf60af1 | 40 | |
c6f3d811 | 41 | f_flags = file->f_flags; |
faf60af1 CG |
42 | if (close_on_exec(fd, fdt)) |
43 | f_flags |= O_CLOEXEC; | |
44 | ||
ddd3e077 CG |
45 | get_file(file); |
46 | ret = 0; | |
faf60af1 CG |
47 | } |
48 | spin_unlock(&files->file_lock); | |
faf60af1 | 49 | } |
775e0656 EB |
50 | task_unlock(task); |
51 | put_task_struct(task); | |
ddd3e077 | 52 | |
6c8c9031 AV |
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 | ||
775e0656 | 60 | /* show_fd_locks() never deferences files so a stale value is safe */ |
6c8c9031 AV |
61 | show_fd_locks(m, file, files); |
62 | if (seq_has_overflowed(m)) | |
63 | goto out; | |
64 | ||
65 | if (file->f_op->show_fdinfo) | |
66 | file->f_op->show_fdinfo(m, file); | |
ddd3e077 | 67 | |
6c8c9031 AV |
68 | out: |
69 | fput(file); | |
70 | return 0; | |
faf60af1 CG |
71 | } |
72 | ||
ddd3e077 CG |
73 | static int seq_fdinfo_open(struct inode *inode, struct file *file) |
74 | { | |
75 | return single_open(file, seq_show, inode); | |
76 | } | |
77 | ||
78 | static const struct file_operations proc_fdinfo_file_operations = { | |
79 | .open = seq_fdinfo_open, | |
80 | .read = seq_read, | |
81 | .llseek = seq_lseek, | |
82 | .release = single_release, | |
83 | }; | |
84 | ||
1ae9bd8b AV |
85 | static bool tid_fd_mode(struct task_struct *task, unsigned fd, fmode_t *mode) |
86 | { | |
1ae9bd8b AV |
87 | struct file *file; |
88 | ||
1ae9bd8b | 89 | rcu_read_lock(); |
64eb661f | 90 | file = task_lookup_fd_rcu(task, fd); |
1ae9bd8b AV |
91 | if (file) |
92 | *mode = file->f_mode; | |
93 | rcu_read_unlock(); | |
1ae9bd8b AV |
94 | return !!file; |
95 | } | |
96 | ||
98836386 AV |
97 | static void tid_fd_update_inode(struct task_struct *task, struct inode *inode, |
98 | fmode_t f_mode) | |
99 | { | |
100 | task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid); | |
101 | ||
102 | if (S_ISLNK(inode->i_mode)) { | |
103 | unsigned i_mode = S_IFLNK; | |
104 | if (f_mode & FMODE_READ) | |
105 | i_mode |= S_IRUSR | S_IXUSR; | |
106 | if (f_mode & FMODE_WRITE) | |
107 | i_mode |= S_IWUSR | S_IXUSR; | |
108 | inode->i_mode = i_mode; | |
109 | } | |
110 | security_task_to_inode(task, inode); | |
111 | } | |
112 | ||
faf60af1 CG |
113 | static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags) |
114 | { | |
faf60af1 | 115 | struct task_struct *task; |
faf60af1 | 116 | struct inode *inode; |
771187d6 | 117 | unsigned int fd; |
faf60af1 CG |
118 | |
119 | if (flags & LOOKUP_RCU) | |
120 | return -ECHILD; | |
121 | ||
2b0143b5 | 122 | inode = d_inode(dentry); |
faf60af1 CG |
123 | task = get_proc_task(inode); |
124 | fd = proc_fd(inode); | |
125 | ||
126 | if (task) { | |
98836386 | 127 | fmode_t f_mode; |
1ae9bd8b | 128 | if (tid_fd_mode(task, fd, &f_mode)) { |
98836386 | 129 | tid_fd_update_inode(task, inode, f_mode); |
1ae9bd8b AV |
130 | put_task_struct(task); |
131 | return 1; | |
faf60af1 CG |
132 | } |
133 | put_task_struct(task); | |
134 | } | |
faf60af1 CG |
135 | return 0; |
136 | } | |
137 | ||
138 | static const struct dentry_operations tid_fd_dentry_operations = { | |
139 | .d_revalidate = tid_fd_revalidate, | |
140 | .d_delete = pid_delete_dentry, | |
141 | }; | |
142 | ||
143 | static int proc_fd_link(struct dentry *dentry, struct path *path) | |
144 | { | |
ddd3e077 CG |
145 | struct task_struct *task; |
146 | int ret = -ENOENT; | |
147 | ||
2b0143b5 | 148 | task = get_proc_task(d_inode(dentry)); |
ddd3e077 | 149 | if (task) { |
771187d6 | 150 | unsigned int fd = proc_fd(d_inode(dentry)); |
ddd3e077 CG |
151 | struct file *fd_file; |
152 | ||
439be326 | 153 | fd_file = fget_task(task, fd); |
ddd3e077 CG |
154 | if (fd_file) { |
155 | *path = fd_file->f_path; | |
156 | path_get(&fd_file->f_path); | |
157 | ret = 0; | |
439be326 | 158 | fput(fd_file); |
ddd3e077 | 159 | } |
439be326 | 160 | put_task_struct(task); |
ddd3e077 CG |
161 | } |
162 | ||
163 | return ret; | |
faf60af1 CG |
164 | } |
165 | ||
98836386 AV |
166 | struct fd_data { |
167 | fmode_t mode; | |
168 | unsigned fd; | |
169 | }; | |
170 | ||
0168b9e3 AV |
171 | static struct dentry *proc_fd_instantiate(struct dentry *dentry, |
172 | struct task_struct *task, const void *ptr) | |
faf60af1 | 173 | { |
98836386 | 174 | const struct fd_data *data = ptr; |
faf60af1 CG |
175 | struct proc_inode *ei; |
176 | struct inode *inode; | |
177 | ||
0168b9e3 | 178 | inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK); |
faf60af1 | 179 | if (!inode) |
0168b9e3 | 180 | return ERR_PTR(-ENOENT); |
faf60af1 CG |
181 | |
182 | ei = PROC_I(inode); | |
98836386 | 183 | ei->fd = data->fd; |
faf60af1 | 184 | |
faf60af1 CG |
185 | inode->i_op = &proc_pid_link_inode_operations; |
186 | inode->i_size = 64; | |
187 | ||
188 | ei->op.proc_get_link = proc_fd_link; | |
98836386 | 189 | tid_fd_update_inode(task, inode, data->mode); |
faf60af1 CG |
190 | |
191 | d_set_d_op(dentry, &tid_fd_dentry_operations); | |
0168b9e3 | 192 | return d_splice_alias(inode, dentry); |
faf60af1 CG |
193 | } |
194 | ||
195 | static struct dentry *proc_lookupfd_common(struct inode *dir, | |
196 | struct dentry *dentry, | |
197 | instantiate_t instantiate) | |
198 | { | |
199 | struct task_struct *task = get_proc_task(dir); | |
98836386 | 200 | struct fd_data data = {.fd = name_to_int(&dentry->d_name)}; |
0168b9e3 | 201 | struct dentry *result = ERR_PTR(-ENOENT); |
faf60af1 CG |
202 | |
203 | if (!task) | |
204 | goto out_no_task; | |
98836386 | 205 | if (data.fd == ~0U) |
faf60af1 | 206 | goto out; |
98836386 | 207 | if (!tid_fd_mode(task, data.fd, &data.mode)) |
1ae9bd8b | 208 | goto out; |
faf60af1 | 209 | |
0168b9e3 | 210 | result = instantiate(dentry, task, &data); |
faf60af1 CG |
211 | out: |
212 | put_task_struct(task); | |
213 | out_no_task: | |
0168b9e3 | 214 | return result; |
faf60af1 CG |
215 | } |
216 | ||
f0c3b509 AV |
217 | static int proc_readfd_common(struct file *file, struct dir_context *ctx, |
218 | instantiate_t instantiate) | |
faf60af1 | 219 | { |
f0c3b509 | 220 | struct task_struct *p = get_proc_task(file_inode(file)); |
f0c3b509 | 221 | unsigned int fd; |
faf60af1 | 222 | |
faf60af1 | 223 | if (!p) |
f0c3b509 | 224 | return -ENOENT; |
faf60af1 | 225 | |
f0c3b509 AV |
226 | if (!dir_emit_dots(file, ctx)) |
227 | goto out; | |
f0c3b509 AV |
228 | |
229 | rcu_read_lock(); | |
5b17b618 | 230 | for (fd = ctx->pos - 2;; fd++) { |
98836386 AV |
231 | struct file *f; |
232 | struct fd_data data; | |
e3912ac3 | 233 | char name[10 + 1]; |
a4ef3895 | 234 | unsigned int len; |
f0c3b509 | 235 | |
5b17b618 EB |
236 | f = task_lookup_next_fd_rcu(p, &fd); |
237 | ctx->pos = fd + 2LL; | |
98836386 | 238 | if (!f) |
5b17b618 | 239 | break; |
98836386 | 240 | data.mode = f->f_mode; |
f0c3b509 | 241 | rcu_read_unlock(); |
98836386 | 242 | data.fd = fd; |
f0c3b509 | 243 | |
771187d6 | 244 | len = snprintf(name, sizeof(name), "%u", fd); |
f0c3b509 AV |
245 | if (!proc_fill_cache(file, ctx, |
246 | name, len, instantiate, p, | |
98836386 | 247 | &data)) |
5b17b618 | 248 | goto out; |
3cc4a84e | 249 | cond_resched(); |
f0c3b509 | 250 | rcu_read_lock(); |
faf60af1 | 251 | } |
f0c3b509 | 252 | rcu_read_unlock(); |
faf60af1 CG |
253 | out: |
254 | put_task_struct(p); | |
f0c3b509 | 255 | return 0; |
faf60af1 CG |
256 | } |
257 | ||
f0c3b509 | 258 | static int proc_readfd(struct file *file, struct dir_context *ctx) |
faf60af1 | 259 | { |
f0c3b509 | 260 | return proc_readfd_common(file, ctx, proc_fd_instantiate); |
faf60af1 CG |
261 | } |
262 | ||
263 | const struct file_operations proc_fd_operations = { | |
264 | .read = generic_read_dir, | |
f50752ea AV |
265 | .iterate_shared = proc_readfd, |
266 | .llseek = generic_file_llseek, | |
faf60af1 CG |
267 | }; |
268 | ||
269 | static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry, | |
270 | unsigned int flags) | |
271 | { | |
272 | return proc_lookupfd_common(dir, dentry, proc_fd_instantiate); | |
273 | } | |
274 | ||
275 | /* | |
276 | * /proc/pid/fd needs a special permission handler so that a process can still | |
277 | * access /proc/self/fd after it has executed a setuid(). | |
278 | */ | |
549c7297 CB |
279 | int proc_fd_permission(struct user_namespace *mnt_userns, |
280 | struct inode *inode, int mask) | |
faf60af1 | 281 | { |
54708d28 ON |
282 | struct task_struct *p; |
283 | int rv; | |
284 | ||
47291baa | 285 | rv = generic_permission(&init_user_ns, inode, mask); |
faf60af1 | 286 | if (rv == 0) |
54708d28 ON |
287 | return rv; |
288 | ||
289 | rcu_read_lock(); | |
290 | p = pid_task(proc_pid(inode), PIDTYPE_PID); | |
291 | if (p && same_thread_group(p, current)) | |
faf60af1 | 292 | rv = 0; |
54708d28 ON |
293 | rcu_read_unlock(); |
294 | ||
faf60af1 CG |
295 | return rv; |
296 | } | |
297 | ||
298 | const struct inode_operations proc_fd_inode_operations = { | |
299 | .lookup = proc_lookupfd, | |
300 | .permission = proc_fd_permission, | |
301 | .setattr = proc_setattr, | |
302 | }; | |
303 | ||
0168b9e3 AV |
304 | static struct dentry *proc_fdinfo_instantiate(struct dentry *dentry, |
305 | struct task_struct *task, const void *ptr) | |
faf60af1 | 306 | { |
98836386 | 307 | const struct fd_data *data = ptr; |
faf60af1 CG |
308 | struct proc_inode *ei; |
309 | struct inode *inode; | |
310 | ||
0168b9e3 | 311 | inode = proc_pid_make_inode(dentry->d_sb, task, S_IFREG | S_IRUSR); |
faf60af1 | 312 | if (!inode) |
0168b9e3 | 313 | return ERR_PTR(-ENOENT); |
faf60af1 CG |
314 | |
315 | ei = PROC_I(inode); | |
98836386 | 316 | ei->fd = data->fd; |
faf60af1 | 317 | |
faf60af1 | 318 | inode->i_fop = &proc_fdinfo_file_operations; |
98836386 | 319 | tid_fd_update_inode(task, inode, 0); |
faf60af1 CG |
320 | |
321 | d_set_d_op(dentry, &tid_fd_dentry_operations); | |
0168b9e3 | 322 | return d_splice_alias(inode, dentry); |
faf60af1 CG |
323 | } |
324 | ||
325 | static struct dentry * | |
326 | proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags) | |
327 | { | |
328 | return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate); | |
329 | } | |
330 | ||
f0c3b509 | 331 | static int proc_readfdinfo(struct file *file, struct dir_context *ctx) |
faf60af1 | 332 | { |
f0c3b509 | 333 | return proc_readfd_common(file, ctx, |
faf60af1 CG |
334 | proc_fdinfo_instantiate); |
335 | } | |
336 | ||
337 | const struct inode_operations proc_fdinfo_inode_operations = { | |
338 | .lookup = proc_lookupfdinfo, | |
339 | .setattr = proc_setattr, | |
340 | }; | |
341 | ||
342 | const struct file_operations proc_fdinfo_operations = { | |
343 | .read = generic_read_dir, | |
f50752ea AV |
344 | .iterate_shared = proc_readfdinfo, |
345 | .llseek = generic_file_llseek, | |
faf60af1 | 346 | }; |