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