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 .ctx.actor = fillonedir, 114 .dirent = dirent 115 }; 116 117 if (!f.file) 118 return -EBADF; 119 120 error = iterate_dir(f.file, &buf.ctx); 121 if (buf.result) 122 error = buf.result; 123 124 fdput(f); 125 return error; 126 } 127 128 #endif /* __ARCH_WANT_OLD_READDIR */ 129 130 /* 131 * New, all-improved, singing, dancing, iBCS2-compliant getdents() 132 * interface. 133 */ 134 struct linux_dirent { 135 unsigned long d_ino; 136 unsigned long d_off; 137 unsigned short d_reclen; 138 char d_name[1]; 139 }; 140 141 struct getdents_callback { 142 struct dir_context ctx; 143 struct linux_dirent __user * current_dir; 144 struct linux_dirent __user * previous; 145 int count; 146 int error; 147 }; 148 149 static int filldir(void * __buf, const char * name, int namlen, loff_t offset, 150 u64 ino, unsigned int d_type) 151 { 152 struct linux_dirent __user * dirent; 153 struct getdents_callback * buf = (struct getdents_callback *) __buf; 154 unsigned long d_ino; 155 int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2, 156 sizeof(long)); 157 158 buf->error = -EINVAL; /* only used if we fail.. */ 159 if (reclen > buf->count) 160 return -EINVAL; 161 d_ino = ino; 162 if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) { 163 buf->error = -EOVERFLOW; 164 return -EOVERFLOW; 165 } 166 dirent = buf->previous; 167 if (dirent) { 168 if (__put_user(offset, &dirent->d_off)) 169 goto efault; 170 } 171 dirent = buf->current_dir; 172 if (__put_user(d_ino, &dirent->d_ino)) 173 goto efault; 174 if (__put_user(reclen, &dirent->d_reclen)) 175 goto efault; 176 if (copy_to_user(dirent->d_name, name, namlen)) 177 goto efault; 178 if (__put_user(0, dirent->d_name + namlen)) 179 goto efault; 180 if (__put_user(d_type, (char __user *) dirent + reclen - 1)) 181 goto efault; 182 buf->previous = dirent; 183 dirent = (void __user *)dirent + reclen; 184 buf->current_dir = dirent; 185 buf->count -= reclen; 186 return 0; 187 efault: 188 buf->error = -EFAULT; 189 return -EFAULT; 190 } 191 192 SYSCALL_DEFINE3(getdents, unsigned int, fd, 193 struct linux_dirent __user *, dirent, unsigned int, count) 194 { 195 struct fd f; 196 struct linux_dirent __user * lastdirent; 197 struct getdents_callback buf = { 198 .ctx.actor = filldir, 199 .count = count, 200 .current_dir = dirent 201 }; 202 int error; 203 204 if (!access_ok(VERIFY_WRITE, dirent, count)) 205 return -EFAULT; 206 207 f = fdget(fd); 208 if (!f.file) 209 return -EBADF; 210 211 error = iterate_dir(f.file, &buf.ctx); 212 if (error >= 0) 213 error = buf.error; 214 lastdirent = buf.previous; 215 if (lastdirent) { 216 if (put_user(buf.ctx.pos, &lastdirent->d_off)) 217 error = -EFAULT; 218 else 219 error = count - buf.count; 220 } 221 fdput(f); 222 return error; 223 } 224 225 struct getdents_callback64 { 226 struct dir_context ctx; 227 struct linux_dirent64 __user * current_dir; 228 struct linux_dirent64 __user * previous; 229 int count; 230 int error; 231 }; 232 233 static int filldir64(void * __buf, const char * name, int namlen, loff_t offset, 234 u64 ino, unsigned int d_type) 235 { 236 struct linux_dirent64 __user *dirent; 237 struct getdents_callback64 * buf = (struct getdents_callback64 *) __buf; 238 int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1, 239 sizeof(u64)); 240 241 buf->error = -EINVAL; /* only used if we fail.. */ 242 if (reclen > buf->count) 243 return -EINVAL; 244 dirent = buf->previous; 245 if (dirent) { 246 if (__put_user(offset, &dirent->d_off)) 247 goto efault; 248 } 249 dirent = buf->current_dir; 250 if (__put_user(ino, &dirent->d_ino)) 251 goto efault; 252 if (__put_user(0, &dirent->d_off)) 253 goto efault; 254 if (__put_user(reclen, &dirent->d_reclen)) 255 goto efault; 256 if (__put_user(d_type, &dirent->d_type)) 257 goto efault; 258 if (copy_to_user(dirent->d_name, name, namlen)) 259 goto efault; 260 if (__put_user(0, dirent->d_name + namlen)) 261 goto efault; 262 buf->previous = dirent; 263 dirent = (void __user *)dirent + reclen; 264 buf->current_dir = dirent; 265 buf->count -= reclen; 266 return 0; 267 efault: 268 buf->error = -EFAULT; 269 return -EFAULT; 270 } 271 272 SYSCALL_DEFINE3(getdents64, unsigned int, fd, 273 struct linux_dirent64 __user *, dirent, unsigned int, count) 274 { 275 struct fd f; 276 struct linux_dirent64 __user * lastdirent; 277 struct getdents_callback64 buf = { 278 .ctx.actor = filldir64, 279 .count = count, 280 .current_dir = dirent 281 }; 282 int error; 283 284 if (!access_ok(VERIFY_WRITE, dirent, count)) 285 return -EFAULT; 286 287 f = fdget(fd); 288 if (!f.file) 289 return -EBADF; 290 291 error = iterate_dir(f.file, &buf.ctx); 292 if (error >= 0) 293 error = buf.error; 294 lastdirent = buf.previous; 295 if (lastdirent) { 296 typeof(lastdirent->d_off) d_off = buf.ctx.pos; 297 if (__put_user(d_off, &lastdirent->d_off)) 298 error = -EFAULT; 299 else 300 error = count - buf.count; 301 } 302 fdput(f); 303 return error; 304 } 305