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