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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 | /* * linux/fs/readdir.c * * Copyright (C) 1995 Linus Torvalds */ #include <linux/stddef.h> #include <linux/kernel.h> #include <linux/export.h> #include <linux/time.h> #include <linux/mm.h> #include <linux/errno.h> #include <linux/stat.h> #include <linux/file.h> #include <linux/fs.h> #include <linux/fsnotify.h> #include <linux/dirent.h> #include <linux/security.h> #include <linux/syscalls.h> #include <linux/unistd.h> #include <asm/uaccess.h> int iterate_dir(struct file *file, struct dir_context *ctx) { struct inode *inode = file_inode(file); int res = -ENOTDIR; if (!file->f_op->iterate) goto out; res = security_file_permission(file, MAY_READ); if (res) goto out; res = mutex_lock_killable(&inode->i_mutex); if (res) goto out; res = -ENOENT; if (!IS_DEADDIR(inode)) { ctx->pos = file->f_pos; res = file->f_op->iterate(file, ctx); file->f_pos = ctx->pos; fsnotify_access(file); file_accessed(file); } mutex_unlock(&inode->i_mutex); out: return res; } EXPORT_SYMBOL(iterate_dir); /* * POSIX says that a dirent name cannot contain NULL or a '/'. * * It's not 100% clear what we should really do in this case. * The filesystem is clearly corrupted, but returning a hard * error means that you now don't see any of the other names * either, so that isn't a perfect alternative. * * And if you return an error, what error do you use? Several * filesystems seem to have decided on EUCLEAN being the error * code for EFSCORRUPTED, and that may be the error to use. Or * just EIO, which is perhaps more obvious to users. * * In order to see the other file names in the directory, the * caller might want to make this a "soft" error: skip the * entry, and return the error at the end instead. * * Note that this should likely do a "memchr(name, 0, len)" * check too, since that would be filesystem corruption as * well. However, that case can't actually confuse user space, * which has to do a strlen() on the name anyway to find the * filename length, and the above "soft error" worry means * that it's probably better left alone until we have that * issue clarified. */ static int verify_dirent_name(const char *name, int len) { if (!len) return -EIO; if (memchr(name, '/', len)) return -EIO; return 0; } /* * Traditional linux readdir() handling.. * * "count=1" is a special case, meaning that the buffer is one * dirent-structure in size and that the code can't handle more * anyway. Thus the special "fillonedir()" function for that * case (the low-level handlers don't need to care about this). */ #ifdef __ARCH_WANT_OLD_READDIR struct old_linux_dirent { unsigned long d_ino; unsigned long d_offset; unsigned short d_namlen; char d_name[1]; }; struct readdir_callback { struct dir_context ctx; struct old_linux_dirent __user * dirent; int result; }; static int fillonedir(struct dir_context *ctx, const char *name, int namlen, loff_t offset, u64 ino, unsigned int d_type) { struct readdir_callback *buf = container_of(ctx, struct readdir_callback, ctx); struct old_linux_dirent __user * dirent; unsigned long d_ino; if (buf->result) return -EINVAL; d_ino = ino; if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) { buf->result = -EOVERFLOW; return -EOVERFLOW; } buf->result++; dirent = buf->dirent; if (!access_ok(VERIFY_WRITE, dirent, (unsigned long)(dirent->d_name + namlen + 1) - (unsigned long)dirent)) goto efault; if ( __put_user(d_ino, &dirent->d_ino) || __put_user(offset, &dirent->d_offset) || __put_user(namlen, &dirent->d_namlen) || __copy_to_user(dirent->d_name, name, namlen) || __put_user(0, dirent->d_name + namlen)) goto efault; return 0; efault: buf->result = -EFAULT; return -EFAULT; } SYSCALL_DEFINE3(old_readdir, unsigned int, fd, struct old_linux_dirent __user *, dirent, unsigned int, count) { int error; struct fd f = fdget(fd); struct readdir_callback buf = { .ctx.actor = fillonedir, .dirent = dirent }; if (!f.file) return -EBADF; error = iterate_dir(f.file, &buf.ctx); if (buf.result) error = buf.result; fdput(f); return error; } #endif /* __ARCH_WANT_OLD_READDIR */ /* * New, all-improved, singing, dancing, iBCS2-compliant getdents() * interface. */ struct linux_dirent { unsigned long d_ino; unsigned long d_off; unsigned short d_reclen; char d_name[1]; }; struct getdents_callback { struct dir_context ctx; struct linux_dirent __user * current_dir; struct linux_dirent __user * previous; int count; int error; }; static int filldir(struct dir_context *ctx, const char *name, int namlen, loff_t offset, u64 ino, unsigned int d_type) { struct linux_dirent __user * dirent; struct getdents_callback *buf = container_of(ctx, struct getdents_callback, ctx); unsigned long d_ino; int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2, sizeof(long)); buf->error = verify_dirent_name(name, namlen); if (unlikely(buf->error)) return buf->error; buf->error = -EINVAL; /* only used if we fail.. */ if (reclen > buf->count) return -EINVAL; d_ino = ino; if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) { buf->error = -EOVERFLOW; return -EOVERFLOW; } dirent = buf->previous; if (dirent) { if (__put_user(offset, &dirent->d_off)) goto efault; } dirent = buf->current_dir; if (__put_user(d_ino, &dirent->d_ino)) goto efault; if (__put_user(reclen, &dirent->d_reclen)) goto efault; if (copy_to_user(dirent->d_name, name, namlen)) goto efault; if (__put_user(0, dirent->d_name + namlen)) goto efault; if (__put_user(d_type, (char __user *) dirent + reclen - 1)) goto efault; buf->previous = dirent; dirent = (void __user *)dirent + reclen; buf->current_dir = dirent; buf->count -= reclen; return 0; efault: buf->error = -EFAULT; return -EFAULT; } SYSCALL_DEFINE3(getdents, unsigned int, fd, struct linux_dirent __user *, dirent, unsigned int, count) { struct fd f; struct linux_dirent __user * lastdirent; struct getdents_callback buf = { .ctx.actor = filldir, .count = count, .current_dir = dirent }; int error; if (!access_ok(VERIFY_WRITE, dirent, count)) return -EFAULT; f = fdget(fd); if (!f.file) return -EBADF; error = iterate_dir(f.file, &buf.ctx); if (error >= 0) error = buf.error; lastdirent = buf.previous; if (lastdirent) { if (put_user(buf.ctx.pos, &lastdirent->d_off)) error = -EFAULT; else error = count - buf.count; } fdput(f); return error; } struct getdents_callback64 { struct dir_context ctx; struct linux_dirent64 __user * current_dir; struct linux_dirent64 __user * previous; int count; int error; }; static int filldir64(struct dir_context *ctx, const char *name, int namlen, loff_t offset, u64 ino, unsigned int d_type) { struct linux_dirent64 __user *dirent; struct getdents_callback64 *buf = container_of(ctx, struct getdents_callback64, ctx); int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1, sizeof(u64)); buf->error = verify_dirent_name(name, namlen); if (unlikely(buf->error)) return buf->error; buf->error = -EINVAL; /* only used if we fail.. */ if (reclen > buf->count) return -EINVAL; dirent = buf->previous; if (dirent) { if (__put_user(offset, &dirent->d_off)) goto efault; } dirent = buf->current_dir; if (__put_user(ino, &dirent->d_ino)) goto efault; if (__put_user(0, &dirent->d_off)) goto efault; if (__put_user(reclen, &dirent->d_reclen)) goto efault; if (__put_user(d_type, &dirent->d_type)) goto efault; if (copy_to_user(dirent->d_name, name, namlen)) goto efault; if (__put_user(0, dirent->d_name + namlen)) goto efault; buf->previous = dirent; dirent = (void __user *)dirent + reclen; buf->current_dir = dirent; buf->count -= reclen; return 0; efault: buf->error = -EFAULT; return -EFAULT; } SYSCALL_DEFINE3(getdents64, unsigned int, fd, struct linux_dirent64 __user *, dirent, unsigned int, count) { struct fd f; struct linux_dirent64 __user * lastdirent; struct getdents_callback64 buf = { .ctx.actor = filldir64, .count = count, .current_dir = dirent }; int error; if (!access_ok(VERIFY_WRITE, dirent, count)) return -EFAULT; f = fdget(fd); if (!f.file) return -EBADF; error = iterate_dir(f.file, &buf.ctx); if (error >= 0) error = buf.error; lastdirent = buf.previous; if (lastdirent) { typeof(lastdirent->d_off) d_off = buf.ctx.pos; if (__put_user(d_off, &lastdirent->d_off)) error = -EFAULT; else error = count - buf.count; } fdput(f); return error; } |