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