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