1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/syscalls.h> 3 #include <linux/export.h> 4 #include <linux/fs.h> 5 #include <linux/file.h> 6 #include <linux/mount.h> 7 #include <linux/namei.h> 8 #include <linux/statfs.h> 9 #include <linux/security.h> 10 #include <linux/uaccess.h> 11 #include <linux/compat.h> 12 #include "internal.h" 13 14 static int flags_by_mnt(int mnt_flags) 15 { 16 int flags = 0; 17 18 if (mnt_flags & MNT_READONLY) 19 flags |= ST_RDONLY; 20 if (mnt_flags & MNT_NOSUID) 21 flags |= ST_NOSUID; 22 if (mnt_flags & MNT_NODEV) 23 flags |= ST_NODEV; 24 if (mnt_flags & MNT_NOEXEC) 25 flags |= ST_NOEXEC; 26 if (mnt_flags & MNT_NOATIME) 27 flags |= ST_NOATIME; 28 if (mnt_flags & MNT_NODIRATIME) 29 flags |= ST_NODIRATIME; 30 if (mnt_flags & MNT_RELATIME) 31 flags |= ST_RELATIME; 32 if (mnt_flags & MNT_NOSYMFOLLOW) 33 flags |= ST_NOSYMFOLLOW; 34 return flags; 35 } 36 37 static int flags_by_sb(int s_flags) 38 { 39 int flags = 0; 40 if (s_flags & SB_SYNCHRONOUS) 41 flags |= ST_SYNCHRONOUS; 42 if (s_flags & SB_MANDLOCK) 43 flags |= ST_MANDLOCK; 44 if (s_flags & SB_RDONLY) 45 flags |= ST_RDONLY; 46 return flags; 47 } 48 49 static int calculate_f_flags(struct vfsmount *mnt) 50 { 51 return ST_VALID | flags_by_mnt(mnt->mnt_flags) | 52 flags_by_sb(mnt->mnt_sb->s_flags); 53 } 54 55 static int statfs_by_dentry(struct dentry *dentry, struct kstatfs *buf) 56 { 57 int retval; 58 59 if (!dentry->d_sb->s_op->statfs) 60 return -ENOSYS; 61 62 memset(buf, 0, sizeof(*buf)); 63 retval = security_sb_statfs(dentry); 64 if (retval) 65 return retval; 66 retval = dentry->d_sb->s_op->statfs(dentry, buf); 67 if (retval == 0 && buf->f_frsize == 0) 68 buf->f_frsize = buf->f_bsize; 69 return retval; 70 } 71 72 int vfs_get_fsid(struct dentry *dentry, __kernel_fsid_t *fsid) 73 { 74 struct kstatfs st; 75 int error; 76 77 error = statfs_by_dentry(dentry, &st); 78 if (error) 79 return error; 80 81 *fsid = st.f_fsid; 82 return 0; 83 } 84 EXPORT_SYMBOL(vfs_get_fsid); 85 86 int vfs_statfs(const struct path *path, struct kstatfs *buf) 87 { 88 int error; 89 90 error = statfs_by_dentry(path->dentry, buf); 91 if (!error) 92 buf->f_flags = calculate_f_flags(path->mnt); 93 return error; 94 } 95 EXPORT_SYMBOL(vfs_statfs); 96 97 int user_statfs(const char __user *pathname, struct kstatfs *st) 98 { 99 struct path path; 100 int error; 101 unsigned int lookup_flags = LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT; 102 CLASS(filename, name)(pathname); 103 retry: 104 error = filename_lookup(AT_FDCWD, name, lookup_flags, &path, NULL); 105 if (!error) { 106 error = vfs_statfs(&path, st); 107 path_put(&path); 108 if (retry_estale(error, lookup_flags)) { 109 lookup_flags |= LOOKUP_REVAL; 110 goto retry; 111 } 112 } 113 return error; 114 } 115 116 int fd_statfs(int fd, struct kstatfs *st) 117 { 118 CLASS(fd_raw, f)(fd); 119 120 if (fd_empty(f)) 121 return -EBADF; 122 return vfs_statfs(&fd_file(f)->f_path, st); 123 } 124 125 static int do_statfs_native(struct kstatfs *st, struct statfs __user *p) 126 { 127 struct statfs buf; 128 129 if (sizeof(buf) == sizeof(*st)) 130 memcpy(&buf, st, sizeof(*st)); 131 else { 132 memset(&buf, 0, sizeof(buf)); 133 if (sizeof buf.f_blocks == 4) { 134 if ((st->f_blocks | st->f_bfree | st->f_bavail | 135 st->f_bsize | st->f_frsize) & 136 0xffffffff00000000ULL) 137 return -EOVERFLOW; 138 /* 139 * f_files and f_ffree may be -1; it's okay to stuff 140 * that into 32 bits 141 */ 142 if (st->f_files != -1 && 143 (st->f_files & 0xffffffff00000000ULL)) 144 return -EOVERFLOW; 145 if (st->f_ffree != -1 && 146 (st->f_ffree & 0xffffffff00000000ULL)) 147 return -EOVERFLOW; 148 } 149 150 buf.f_type = st->f_type; 151 buf.f_bsize = st->f_bsize; 152 buf.f_blocks = st->f_blocks; 153 buf.f_bfree = st->f_bfree; 154 buf.f_bavail = st->f_bavail; 155 buf.f_files = st->f_files; 156 buf.f_ffree = st->f_ffree; 157 buf.f_fsid = st->f_fsid; 158 buf.f_namelen = st->f_namelen; 159 buf.f_frsize = st->f_frsize; 160 buf.f_flags = st->f_flags; 161 } 162 if (copy_to_user(p, &buf, sizeof(buf))) 163 return -EFAULT; 164 return 0; 165 } 166 167 static int do_statfs64(struct kstatfs *st, struct statfs64 __user *p) 168 { 169 struct statfs64 buf; 170 if (sizeof(buf) == sizeof(*st)) 171 memcpy(&buf, st, sizeof(*st)); 172 else { 173 memset(&buf, 0, sizeof(buf)); 174 buf.f_type = st->f_type; 175 buf.f_bsize = st->f_bsize; 176 buf.f_blocks = st->f_blocks; 177 buf.f_bfree = st->f_bfree; 178 buf.f_bavail = st->f_bavail; 179 buf.f_files = st->f_files; 180 buf.f_ffree = st->f_ffree; 181 buf.f_fsid = st->f_fsid; 182 buf.f_namelen = st->f_namelen; 183 buf.f_frsize = st->f_frsize; 184 buf.f_flags = st->f_flags; 185 } 186 if (copy_to_user(p, &buf, sizeof(buf))) 187 return -EFAULT; 188 return 0; 189 } 190 191 SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct statfs __user *, buf) 192 { 193 struct kstatfs st; 194 int error = user_statfs(pathname, &st); 195 if (!error) 196 error = do_statfs_native(&st, buf); 197 return error; 198 } 199 200 SYSCALL_DEFINE3(statfs64, const char __user *, pathname, size_t, sz, struct statfs64 __user *, buf) 201 { 202 struct kstatfs st; 203 int error; 204 if (sz != sizeof(*buf)) 205 return -EINVAL; 206 error = user_statfs(pathname, &st); 207 if (!error) 208 error = do_statfs64(&st, buf); 209 return error; 210 } 211 212 SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct statfs __user *, buf) 213 { 214 struct kstatfs st; 215 int error = fd_statfs(fd, &st); 216 if (!error) 217 error = do_statfs_native(&st, buf); 218 return error; 219 } 220 221 SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, size_t, sz, struct statfs64 __user *, buf) 222 { 223 struct kstatfs st; 224 int error; 225 226 if (sz != sizeof(*buf)) 227 return -EINVAL; 228 229 error = fd_statfs(fd, &st); 230 if (!error) 231 error = do_statfs64(&st, buf); 232 return error; 233 } 234 235 static int vfs_ustat(dev_t dev, struct kstatfs *sbuf) 236 { 237 struct super_block *s = user_get_super(dev, false); 238 int err; 239 if (!s) 240 return -EINVAL; 241 242 err = statfs_by_dentry(s->s_root, sbuf); 243 drop_super(s); 244 return err; 245 } 246 247 SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf) 248 { 249 struct ustat tmp; 250 struct kstatfs sbuf; 251 int err = vfs_ustat(new_decode_dev(dev), &sbuf); 252 if (err) 253 return err; 254 255 memset(&tmp,0,sizeof(struct ustat)); 256 tmp.f_tfree = sbuf.f_bfree; 257 if (IS_ENABLED(CONFIG_ARCH_32BIT_USTAT_F_TINODE)) 258 tmp.f_tinode = min_t(u64, sbuf.f_ffree, UINT_MAX); 259 else 260 tmp.f_tinode = sbuf.f_ffree; 261 262 return copy_to_user(ubuf, &tmp, sizeof(struct ustat)) ? -EFAULT : 0; 263 } 264 265 #ifdef CONFIG_COMPAT 266 static int put_compat_statfs(struct compat_statfs __user *ubuf, struct kstatfs *kbuf) 267 { 268 struct compat_statfs buf; 269 if (sizeof ubuf->f_blocks == 4) { 270 if ((kbuf->f_blocks | kbuf->f_bfree | kbuf->f_bavail | 271 kbuf->f_bsize | kbuf->f_frsize) & 0xffffffff00000000ULL) 272 return -EOVERFLOW; 273 /* f_files and f_ffree may be -1; it's okay 274 * to stuff that into 32 bits */ 275 if (kbuf->f_files != 0xffffffffffffffffULL 276 && (kbuf->f_files & 0xffffffff00000000ULL)) 277 return -EOVERFLOW; 278 if (kbuf->f_ffree != 0xffffffffffffffffULL 279 && (kbuf->f_ffree & 0xffffffff00000000ULL)) 280 return -EOVERFLOW; 281 } 282 memset(&buf, 0, sizeof(struct compat_statfs)); 283 buf.f_type = kbuf->f_type; 284 buf.f_bsize = kbuf->f_bsize; 285 buf.f_blocks = kbuf->f_blocks; 286 buf.f_bfree = kbuf->f_bfree; 287 buf.f_bavail = kbuf->f_bavail; 288 buf.f_files = kbuf->f_files; 289 buf.f_ffree = kbuf->f_ffree; 290 buf.f_namelen = kbuf->f_namelen; 291 buf.f_fsid.val[0] = kbuf->f_fsid.val[0]; 292 buf.f_fsid.val[1] = kbuf->f_fsid.val[1]; 293 buf.f_frsize = kbuf->f_frsize; 294 buf.f_flags = kbuf->f_flags; 295 if (copy_to_user(ubuf, &buf, sizeof(struct compat_statfs))) 296 return -EFAULT; 297 return 0; 298 } 299 300 /* 301 * The following statfs calls are copies of code from fs/statfs.c and 302 * should be checked against those from time to time 303 */ 304 COMPAT_SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct compat_statfs __user *, buf) 305 { 306 struct kstatfs tmp; 307 int error = user_statfs(pathname, &tmp); 308 if (!error) 309 error = put_compat_statfs(buf, &tmp); 310 return error; 311 } 312 313 COMPAT_SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct compat_statfs __user *, buf) 314 { 315 struct kstatfs tmp; 316 int error = fd_statfs(fd, &tmp); 317 if (!error) 318 error = put_compat_statfs(buf, &tmp); 319 return error; 320 } 321 322 static int put_compat_statfs64(struct compat_statfs64 __user *ubuf, struct kstatfs *kbuf) 323 { 324 struct compat_statfs64 buf; 325 326 if ((kbuf->f_bsize | kbuf->f_frsize) & 0xffffffff00000000ULL) 327 return -EOVERFLOW; 328 329 memset(&buf, 0, sizeof(struct compat_statfs64)); 330 buf.f_type = kbuf->f_type; 331 buf.f_bsize = kbuf->f_bsize; 332 buf.f_blocks = kbuf->f_blocks; 333 buf.f_bfree = kbuf->f_bfree; 334 buf.f_bavail = kbuf->f_bavail; 335 buf.f_files = kbuf->f_files; 336 buf.f_ffree = kbuf->f_ffree; 337 buf.f_namelen = kbuf->f_namelen; 338 buf.f_fsid.val[0] = kbuf->f_fsid.val[0]; 339 buf.f_fsid.val[1] = kbuf->f_fsid.val[1]; 340 buf.f_frsize = kbuf->f_frsize; 341 buf.f_flags = kbuf->f_flags; 342 if (copy_to_user(ubuf, &buf, sizeof(struct compat_statfs64))) 343 return -EFAULT; 344 return 0; 345 } 346 347 int kcompat_sys_statfs64(const char __user * pathname, compat_size_t sz, struct compat_statfs64 __user * buf) 348 { 349 struct kstatfs tmp; 350 int error; 351 352 if (sz != sizeof(*buf)) 353 return -EINVAL; 354 355 error = user_statfs(pathname, &tmp); 356 if (!error) 357 error = put_compat_statfs64(buf, &tmp); 358 return error; 359 } 360 361 COMPAT_SYSCALL_DEFINE3(statfs64, const char __user *, pathname, compat_size_t, sz, struct compat_statfs64 __user *, buf) 362 { 363 return kcompat_sys_statfs64(pathname, sz, buf); 364 } 365 366 int kcompat_sys_fstatfs64(unsigned int fd, compat_size_t sz, struct compat_statfs64 __user * buf) 367 { 368 struct kstatfs tmp; 369 int error; 370 371 if (sz != sizeof(*buf)) 372 return -EINVAL; 373 374 error = fd_statfs(fd, &tmp); 375 if (!error) 376 error = put_compat_statfs64(buf, &tmp); 377 return error; 378 } 379 380 COMPAT_SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, compat_size_t, sz, struct compat_statfs64 __user *, buf) 381 { 382 return kcompat_sys_fstatfs64(fd, sz, buf); 383 } 384 385 /* 386 * This is a copy of sys_ustat, just dealing with a structure layout. 387 * Given how simple this syscall is that apporach is more maintainable 388 * than the various conversion hacks. 389 */ 390 COMPAT_SYSCALL_DEFINE2(ustat, unsigned, dev, struct compat_ustat __user *, u) 391 { 392 struct compat_ustat tmp; 393 struct kstatfs sbuf; 394 int err = vfs_ustat(new_decode_dev(dev), &sbuf); 395 if (err) 396 return err; 397 398 memset(&tmp, 0, sizeof(struct compat_ustat)); 399 tmp.f_tfree = sbuf.f_bfree; 400 tmp.f_tinode = sbuf.f_ffree; 401 if (copy_to_user(u, &tmp, sizeof(struct compat_ustat))) 402 return -EFAULT; 403 return 0; 404 } 405 #endif 406