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1 | /* | |
2 | * linux/fs/readdir.c | |
3 | * | |
4 | * Copyright (C) 1995 Linus Torvalds | |
5 | */ | |
6 | ||
7 | #include <linux/stddef.h> | |
8 | #include <linux/kernel.h> | |
9 | #include <linux/export.h> | |
10 | #include <linux/time.h> | |
11 | #include <linux/mm.h> | |
12 | #include <linux/errno.h> | |
13 | #include <linux/stat.h> | |
14 | #include <linux/file.h> | |
15 | #include <linux/fs.h> | |
16 | #include <linux/fsnotify.h> | |
17 | #include <linux/dirent.h> | |
18 | #include <linux/security.h> | |
19 | #include <linux/syscalls.h> | |
20 | #include <linux/unistd.h> | |
21 | ||
22 | #include <linux/uaccess.h> | |
23 | ||
24 | int iterate_dir(struct file *file, struct dir_context *ctx) | |
25 | { | |
26 | struct inode *inode = file_inode(file); | |
27 | bool shared = false; | |
28 | int res = -ENOTDIR; | |
29 | if (file->f_op->iterate_shared) | |
30 | shared = true; | |
31 | else if (!file->f_op->iterate) | |
32 | goto out; | |
33 | ||
34 | res = security_file_permission(file, MAY_READ); | |
35 | if (res) | |
36 | goto out; | |
37 | ||
38 | if (shared) { | |
39 | inode_lock_shared(inode); | |
40 | } else { | |
41 | res = down_write_killable(&inode->i_rwsem); | |
42 | if (res) | |
43 | goto out; | |
44 | } | |
45 | ||
46 | res = -ENOENT; | |
47 | if (!IS_DEADDIR(inode)) { | |
48 | ctx->pos = file->f_pos; | |
49 | if (shared) | |
50 | res = file->f_op->iterate_shared(file, ctx); | |
51 | else | |
52 | res = file->f_op->iterate(file, ctx); | |
53 | file->f_pos = ctx->pos; | |
54 | fsnotify_access(file); | |
55 | file_accessed(file); | |
56 | } | |
57 | if (shared) | |
58 | inode_unlock_shared(inode); | |
59 | else | |
60 | inode_unlock(inode); | |
61 | out: | |
62 | return res; | |
63 | } | |
64 | EXPORT_SYMBOL(iterate_dir); | |
65 | ||
66 | /* | |
67 | * Traditional linux readdir() handling.. | |
68 | * | |
69 | * "count=1" is a special case, meaning that the buffer is one | |
70 | * dirent-structure in size and that the code can't handle more | |
71 | * anyway. Thus the special "fillonedir()" function for that | |
72 | * case (the low-level handlers don't need to care about this). | |
73 | */ | |
74 | ||
75 | #ifdef __ARCH_WANT_OLD_READDIR | |
76 | ||
77 | struct old_linux_dirent { | |
78 | unsigned long d_ino; | |
79 | unsigned long d_offset; | |
80 | unsigned short d_namlen; | |
81 | char d_name[1]; | |
82 | }; | |
83 | ||
84 | struct readdir_callback { | |
85 | struct dir_context ctx; | |
86 | struct old_linux_dirent __user * dirent; | |
87 | int result; | |
88 | }; | |
89 | ||
90 | static int fillonedir(struct dir_context *ctx, const char *name, int namlen, | |
91 | loff_t offset, u64 ino, unsigned int d_type) | |
92 | { | |
93 | struct readdir_callback *buf = | |
94 | container_of(ctx, struct readdir_callback, ctx); | |
95 | struct old_linux_dirent __user * dirent; | |
96 | unsigned long d_ino; | |
97 | ||
98 | if (buf->result) | |
99 | return -EINVAL; | |
100 | d_ino = ino; | |
101 | if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) { | |
102 | buf->result = -EOVERFLOW; | |
103 | return -EOVERFLOW; | |
104 | } | |
105 | buf->result++; | |
106 | dirent = buf->dirent; | |
107 | if (!access_ok(VERIFY_WRITE, dirent, | |
108 | (unsigned long)(dirent->d_name + namlen + 1) - | |
109 | (unsigned long)dirent)) | |
110 | goto efault; | |
111 | if ( __put_user(d_ino, &dirent->d_ino) || | |
112 | __put_user(offset, &dirent->d_offset) || | |
113 | __put_user(namlen, &dirent->d_namlen) || | |
114 | __copy_to_user(dirent->d_name, name, namlen) || | |
115 | __put_user(0, dirent->d_name + namlen)) | |
116 | goto efault; | |
117 | return 0; | |
118 | efault: | |
119 | buf->result = -EFAULT; | |
120 | return -EFAULT; | |
121 | } | |
122 | ||
123 | SYSCALL_DEFINE3(old_readdir, unsigned int, fd, | |
124 | struct old_linux_dirent __user *, dirent, unsigned int, count) | |
125 | { | |
126 | int error; | |
127 | struct fd f = fdget_pos(fd); | |
128 | struct readdir_callback buf = { | |
129 | .ctx.actor = fillonedir, | |
130 | .dirent = dirent | |
131 | }; | |
132 | ||
133 | if (!f.file) | |
134 | return -EBADF; | |
135 | ||
136 | error = iterate_dir(f.file, &buf.ctx); | |
137 | if (buf.result) | |
138 | error = buf.result; | |
139 | ||
140 | fdput_pos(f); | |
141 | return error; | |
142 | } | |
143 | ||
144 | #endif /* __ARCH_WANT_OLD_READDIR */ | |
145 | ||
146 | /* | |
147 | * New, all-improved, singing, dancing, iBCS2-compliant getdents() | |
148 | * interface. | |
149 | */ | |
150 | struct linux_dirent { | |
151 | unsigned long d_ino; | |
152 | unsigned long d_off; | |
153 | unsigned short d_reclen; | |
154 | char d_name[1]; | |
155 | }; | |
156 | ||
157 | struct getdents_callback { | |
158 | struct dir_context ctx; | |
159 | struct linux_dirent __user * current_dir; | |
160 | struct linux_dirent __user * previous; | |
161 | int count; | |
162 | int error; | |
163 | }; | |
164 | ||
165 | static int filldir(struct dir_context *ctx, const char *name, int namlen, | |
166 | loff_t offset, u64 ino, unsigned int d_type) | |
167 | { | |
168 | struct linux_dirent __user * dirent; | |
169 | struct getdents_callback *buf = | |
170 | container_of(ctx, struct getdents_callback, ctx); | |
171 | unsigned long d_ino; | |
172 | int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2, | |
173 | sizeof(long)); | |
174 | ||
175 | buf->error = -EINVAL; /* only used if we fail.. */ | |
176 | if (reclen > buf->count) | |
177 | return -EINVAL; | |
178 | d_ino = ino; | |
179 | if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) { | |
180 | buf->error = -EOVERFLOW; | |
181 | return -EOVERFLOW; | |
182 | } | |
183 | dirent = buf->previous; | |
184 | if (dirent) { | |
185 | if (signal_pending(current)) | |
186 | return -EINTR; | |
187 | if (__put_user(offset, &dirent->d_off)) | |
188 | goto efault; | |
189 | } | |
190 | dirent = buf->current_dir; | |
191 | if (__put_user(d_ino, &dirent->d_ino)) | |
192 | goto efault; | |
193 | if (__put_user(reclen, &dirent->d_reclen)) | |
194 | goto efault; | |
195 | if (copy_to_user(dirent->d_name, name, namlen)) | |
196 | goto efault; | |
197 | if (__put_user(0, dirent->d_name + namlen)) | |
198 | goto efault; | |
199 | if (__put_user(d_type, (char __user *) dirent + reclen - 1)) | |
200 | goto efault; | |
201 | buf->previous = dirent; | |
202 | dirent = (void __user *)dirent + reclen; | |
203 | buf->current_dir = dirent; | |
204 | buf->count -= reclen; | |
205 | return 0; | |
206 | efault: | |
207 | buf->error = -EFAULT; | |
208 | return -EFAULT; | |
209 | } | |
210 | ||
211 | SYSCALL_DEFINE3(getdents, unsigned int, fd, | |
212 | struct linux_dirent __user *, dirent, unsigned int, count) | |
213 | { | |
214 | struct fd f; | |
215 | struct linux_dirent __user * lastdirent; | |
216 | struct getdents_callback buf = { | |
217 | .ctx.actor = filldir, | |
218 | .count = count, | |
219 | .current_dir = dirent | |
220 | }; | |
221 | int error; | |
222 | ||
223 | if (!access_ok(VERIFY_WRITE, dirent, count)) | |
224 | return -EFAULT; | |
225 | ||
226 | f = fdget_pos(fd); | |
227 | if (!f.file) | |
228 | return -EBADF; | |
229 | ||
230 | error = iterate_dir(f.file, &buf.ctx); | |
231 | if (error >= 0) | |
232 | error = buf.error; | |
233 | lastdirent = buf.previous; | |
234 | if (lastdirent) { | |
235 | if (put_user(buf.ctx.pos, &lastdirent->d_off)) | |
236 | error = -EFAULT; | |
237 | else | |
238 | error = count - buf.count; | |
239 | } | |
240 | fdput_pos(f); | |
241 | return error; | |
242 | } | |
243 | ||
244 | struct getdents_callback64 { | |
245 | struct dir_context ctx; | |
246 | struct linux_dirent64 __user * current_dir; | |
247 | struct linux_dirent64 __user * previous; | |
248 | int count; | |
249 | int error; | |
250 | }; | |
251 | ||
252 | static int filldir64(struct dir_context *ctx, const char *name, int namlen, | |
253 | loff_t offset, u64 ino, unsigned int d_type) | |
254 | { | |
255 | struct linux_dirent64 __user *dirent; | |
256 | struct getdents_callback64 *buf = | |
257 | container_of(ctx, struct getdents_callback64, ctx); | |
258 | int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1, | |
259 | sizeof(u64)); | |
260 | ||
261 | buf->error = -EINVAL; /* only used if we fail.. */ | |
262 | if (reclen > buf->count) | |
263 | return -EINVAL; | |
264 | dirent = buf->previous; | |
265 | if (dirent) { | |
266 | if (signal_pending(current)) | |
267 | return -EINTR; | |
268 | if (__put_user(offset, &dirent->d_off)) | |
269 | goto efault; | |
270 | } | |
271 | dirent = buf->current_dir; | |
272 | if (__put_user(ino, &dirent->d_ino)) | |
273 | goto efault; | |
274 | if (__put_user(0, &dirent->d_off)) | |
275 | goto efault; | |
276 | if (__put_user(reclen, &dirent->d_reclen)) | |
277 | goto efault; | |
278 | if (__put_user(d_type, &dirent->d_type)) | |
279 | goto efault; | |
280 | if (copy_to_user(dirent->d_name, name, namlen)) | |
281 | goto efault; | |
282 | if (__put_user(0, dirent->d_name + namlen)) | |
283 | goto efault; | |
284 | buf->previous = dirent; | |
285 | dirent = (void __user *)dirent + reclen; | |
286 | buf->current_dir = dirent; | |
287 | buf->count -= reclen; | |
288 | return 0; | |
289 | efault: | |
290 | buf->error = -EFAULT; | |
291 | return -EFAULT; | |
292 | } | |
293 | ||
294 | SYSCALL_DEFINE3(getdents64, unsigned int, fd, | |
295 | struct linux_dirent64 __user *, dirent, unsigned int, count) | |
296 | { | |
297 | struct fd f; | |
298 | struct linux_dirent64 __user * lastdirent; | |
299 | struct getdents_callback64 buf = { | |
300 | .ctx.actor = filldir64, | |
301 | .count = count, | |
302 | .current_dir = dirent | |
303 | }; | |
304 | int error; | |
305 | ||
306 | if (!access_ok(VERIFY_WRITE, dirent, count)) | |
307 | return -EFAULT; | |
308 | ||
309 | f = fdget_pos(fd); | |
310 | if (!f.file) | |
311 | return -EBADF; | |
312 | ||
313 | error = iterate_dir(f.file, &buf.ctx); | |
314 | if (error >= 0) | |
315 | error = buf.error; | |
316 | lastdirent = buf.previous; | |
317 | if (lastdirent) { | |
318 | typeof(lastdirent->d_off) d_off = buf.ctx.pos; | |
319 | if (__put_user(d_off, &lastdirent->d_off)) | |
320 | error = -EFAULT; | |
321 | else | |
322 | error = count - buf.count; | |
323 | } | |
324 | fdput_pos(f); | |
325 | return error; | |
326 | } |