fs/statfs.c

   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 retry:
 103         error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
 104         if (!error) {
 105                 error = vfs_statfs(&path, st);
 106                 path_put(&path);
 107                 if (retry_estale(error, lookup_flags)) {
 108                         lookup_flags |= LOOKUP_REVAL;
 109                         goto retry;
 110                 }
 111         }
 112         return error;
 113 }
 114
 115 int fd_statfs(int fd, struct kstatfs *st)
 116 {
 117         CLASS(fd_raw, f)(fd);
 118
 119         if (fd_empty(f))
 120                 return -EBADF;
 121         return vfs_statfs(&fd_file(f)->f_path, st);
 122 }
 123
 124 static int do_statfs_native(struct kstatfs *st, struct statfs __user *p)
 125 {
 126         struct statfs buf;
 127
 128         if (sizeof(buf) == sizeof(*st))
 129                 memcpy(&buf, st, sizeof(*st));
 130         else {
 131                 memset(&buf, 0, sizeof(buf));
 132                 if (sizeof buf.f_blocks == 4) {
 133                         if ((st->f_blocks | st->f_bfree | st->f_bavail |
 134                              st->f_bsize | st->f_frsize) &
 135                             0xffffffff00000000ULL)
 136                                 return -EOVERFLOW;
 137                         /*
 138                          * f_files and f_ffree may be -1; it's okay to stuff
 139                          * that into 32 bits
 140                          */
 141                         if (st->f_files != -1 &&
 142                             (st->f_files & 0xffffffff00000000ULL))
 143                                 return -EOVERFLOW;
 144                         if (st->f_ffree != -1 &&
 145                             (st->f_ffree & 0xffffffff00000000ULL))
 146                                 return -EOVERFLOW;
 147                 }
 148
 149                 buf.f_type = st->f_type;
 150                 buf.f_bsize = st->f_bsize;
 151                 buf.f_blocks = st->f_blocks;
 152                 buf.f_bfree = st->f_bfree;
 153                 buf.f_bavail = st->f_bavail;
 154                 buf.f_files = st->f_files;
 155                 buf.f_ffree = st->f_ffree;
 156                 buf.f_fsid = st->f_fsid;
 157                 buf.f_namelen = st->f_namelen;
 158                 buf.f_frsize = st->f_frsize;
 159                 buf.f_flags = st->f_flags;
 160         }
 161         if (copy_to_user(p, &buf, sizeof(buf)))
 162                 return -EFAULT;
 163         return 0;
 164 }
 165
 166 static int do_statfs64(struct kstatfs *st, struct statfs64 __user *p)
 167 {
 168         struct statfs64 buf;
 169         if (sizeof(buf) == sizeof(*st))
 170                 memcpy(&buf, st, sizeof(*st));
 171         else {
 172                 memset(&buf, 0, sizeof(buf));
 173                 buf.f_type = st->f_type;
 174                 buf.f_bsize = st->f_bsize;
 175                 buf.f_blocks = st->f_blocks;
 176                 buf.f_bfree = st->f_bfree;
 177                 buf.f_bavail = st->f_bavail;
 178                 buf.f_files = st->f_files;
 179                 buf.f_ffree = st->f_ffree;
 180                 buf.f_fsid = st->f_fsid;
 181                 buf.f_namelen = st->f_namelen;
 182                 buf.f_frsize = st->f_frsize;
 183                 buf.f_flags = st->f_flags;
 184         }
 185         if (copy_to_user(p, &buf, sizeof(buf)))
 186                 return -EFAULT;
 187         return 0;
 188 }
 189
 190 SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct statfs __user *, buf)
 191 {
 192         struct kstatfs st;
 193         int error = user_statfs(pathname, &st);
 194         if (!error)
 195                 error = do_statfs_native(&st, buf);
 196         return error;
 197 }
 198
 199 SYSCALL_DEFINE3(statfs64, const char __user *, pathname, size_t, sz, struct statfs64 __user *, buf)
 200 {
 201         struct kstatfs st;
 202         int error;
 203         if (sz != sizeof(*buf))
 204                 return -EINVAL;
 205         error = user_statfs(pathname, &st);
 206         if (!error)
 207                 error = do_statfs64(&st, buf);
 208         return error;
 209 }
 210
 211 SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct statfs __user *, buf)
 212 {
 213         struct kstatfs st;
 214         int error = fd_statfs(fd, &st);
 215         if (!error)
 216                 error = do_statfs_native(&st, buf);
 217         return error;
 218 }
 219
 220 SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, size_t, sz, struct statfs64 __user *, buf)
 221 {
 222         struct kstatfs st;
 223         int error;
 224
 225         if (sz != sizeof(*buf))
 226                 return -EINVAL;
 227
 228         error = fd_statfs(fd, &st);
 229         if (!error)
 230                 error = do_statfs64(&st, buf);
 231         return error;
 232 }
 233
 234 static int vfs_ustat(dev_t dev, struct kstatfs *sbuf)
 235 {
 236         struct super_block *s = user_get_super(dev, false);
 237         int err;
 238         if (!s)
 239                 return -EINVAL;
 240
 241         err = statfs_by_dentry(s->s_root, sbuf);
 242         drop_super(s);
 243         return err;
 244 }
 245
 246 SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf)
 247 {
 248         struct ustat tmp;
 249         struct kstatfs sbuf;
 250         int err = vfs_ustat(new_decode_dev(dev), &sbuf);
 251         if (err)
 252                 return err;
 253
 254         memset(&tmp,0,sizeof(struct ustat));
 255         tmp.f_tfree = sbuf.f_bfree;
 256         if (IS_ENABLED(CONFIG_ARCH_32BIT_USTAT_F_TINODE))
 257                 tmp.f_tinode = min_t(u64, sbuf.f_ffree, UINT_MAX);
 258         else
 259                 tmp.f_tinode = sbuf.f_ffree;
 260
 261         return copy_to_user(ubuf, &tmp, sizeof(struct ustat)) ? -EFAULT : 0;
 262 }
 263
 264 #ifdef CONFIG_COMPAT
 265 static int put_compat_statfs(struct compat_statfs __user *ubuf, struct kstatfs *kbuf)
 266 {
 267         struct compat_statfs buf;
 268         if (sizeof ubuf->f_blocks == 4) {
 269                 if ((kbuf->f_blocks | kbuf->f_bfree | kbuf->f_bavail |
 270                      kbuf->f_bsize | kbuf->f_frsize) & 0xffffffff00000000ULL)
 271                         return -EOVERFLOW;
 272                 /* f_files and f_ffree may be -1; it's okay
 273                  * to stuff that into 32 bits */
 274                 if (kbuf->f_files != 0xffffffffffffffffULL
 275                  && (kbuf->f_files & 0xffffffff00000000ULL))
 276                         return -EOVERFLOW;
 277                 if (kbuf->f_ffree != 0xffffffffffffffffULL
 278                  && (kbuf->f_ffree & 0xffffffff00000000ULL))
 279                         return -EOVERFLOW;
 280         }
 281         memset(&buf, 0, sizeof(struct compat_statfs));
 282         buf.f_type = kbuf->f_type;
 283         buf.f_bsize = kbuf->f_bsize;
 284         buf.f_blocks = kbuf->f_blocks;
 285         buf.f_bfree = kbuf->f_bfree;
 286         buf.f_bavail = kbuf->f_bavail;
 287         buf.f_files = kbuf->f_files;
 288         buf.f_ffree = kbuf->f_ffree;
 289         buf.f_namelen = kbuf->f_namelen;
 290         buf.f_fsid.val[0] = kbuf->f_fsid.val[0];
 291         buf.f_fsid.val[1] = kbuf->f_fsid.val[1];
 292         buf.f_frsize = kbuf->f_frsize;
 293         buf.f_flags = kbuf->f_flags;
 294         if (copy_to_user(ubuf, &buf, sizeof(struct compat_statfs)))
 295                 return -EFAULT;
 296         return 0;
 297 }
 298
 299 /*
 300  * The following statfs calls are copies of code from fs/statfs.c and
 301  * should be checked against those from time to time
 302  */
 303 COMPAT_SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct compat_statfs __user *, buf)
 304 {
 305         struct kstatfs tmp;
 306         int error = user_statfs(pathname, &tmp);
 307         if (!error)
 308                 error = put_compat_statfs(buf, &tmp);
 309         return error;
 310 }
 311
 312 COMPAT_SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct compat_statfs __user *, buf)
 313 {
 314         struct kstatfs tmp;
 315         int error = fd_statfs(fd, &tmp);
 316         if (!error)
 317                 error = put_compat_statfs(buf, &tmp);
 318         return error;
 319 }
 320
 321 static int put_compat_statfs64(struct compat_statfs64 __user *ubuf, struct kstatfs *kbuf)
 322 {
 323         struct compat_statfs64 buf;
 324
 325         if ((kbuf->f_bsize | kbuf->f_frsize) & 0xffffffff00000000ULL)
 326                 return -EOVERFLOW;
 327
 328         memset(&buf, 0, sizeof(struct compat_statfs64));
 329         buf.f_type = kbuf->f_type;
 330         buf.f_bsize = kbuf->f_bsize;
 331         buf.f_blocks = kbuf->f_blocks;
 332         buf.f_bfree = kbuf->f_bfree;
 333         buf.f_bavail = kbuf->f_bavail;
 334         buf.f_files = kbuf->f_files;
 335         buf.f_ffree = kbuf->f_ffree;
 336         buf.f_namelen = kbuf->f_namelen;
 337         buf.f_fsid.val[0] = kbuf->f_fsid.val[0];
 338         buf.f_fsid.val[1] = kbuf->f_fsid.val[1];
 339         buf.f_frsize = kbuf->f_frsize;
 340         buf.f_flags = kbuf->f_flags;
 341         if (copy_to_user(ubuf, &buf, sizeof(struct compat_statfs64)))
 342                 return -EFAULT;
 343         return 0;
 344 }
 345
 346 int kcompat_sys_statfs64(const char __user * pathname, compat_size_t sz, struct compat_statfs64 __user * buf)
 347 {
 348         struct kstatfs tmp;
 349         int error;
 350
 351         if (sz != sizeof(*buf))
 352                 return -EINVAL;
 353
 354         error = user_statfs(pathname, &tmp);
 355         if (!error)
 356                 error = put_compat_statfs64(buf, &tmp);
 357         return error;
 358 }
 359
 360 COMPAT_SYSCALL_DEFINE3(statfs64, const char __user *, pathname, compat_size_t, sz, struct compat_statfs64 __user *, buf)
 361 {
 362         return kcompat_sys_statfs64(pathname, sz, buf);
 363 }
 364
 365 int kcompat_sys_fstatfs64(unsigned int fd, compat_size_t sz, struct compat_statfs64 __user * buf)
 366 {
 367         struct kstatfs tmp;
 368         int error;
 369
 370         if (sz != sizeof(*buf))
 371                 return -EINVAL;
 372
 373         error = fd_statfs(fd, &tmp);
 374         if (!error)
 375                 error = put_compat_statfs64(buf, &tmp);
 376         return error;
 377 }
 378
 379 COMPAT_SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, compat_size_t, sz, struct compat_statfs64 __user *, buf)
 380 {
 381         return kcompat_sys_fstatfs64(fd, sz, buf);
 382 }
 383
 384 /*
 385  * This is a copy of sys_ustat, just dealing with a structure layout.
 386  * Given how simple this syscall is that apporach is more maintainable
 387  * than the various conversion hacks.
 388  */
 389 COMPAT_SYSCALL_DEFINE2(ustat, unsigned, dev, struct compat_ustat __user *, u)
 390 {
 391         struct compat_ustat tmp;
 392         struct kstatfs sbuf;
 393         int err = vfs_ustat(new_decode_dev(dev), &sbuf);
 394         if (err)
 395                 return err;
 396
 397         memset(&tmp, 0, sizeof(struct compat_ustat));
 398         tmp.f_tfree = sbuf.f_bfree;
 399         tmp.f_tinode = sbuf.f_ffree;
 400         if (copy_to_user(u, &tmp, sizeof(struct compat_ustat)))
 401                 return -EFAULT;
 402         return 0;
 403 }
 404 #endif