fs/exfat/file.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
   4  */
   5
   6 #include <linux/slab.h>
   7 #include <linux/cred.h>
   8 #include <linux/buffer_head.h>
   9 #include <linux/blkdev.h>
  10
  11 #include "exfat_raw.h"
  12 #include "exfat_fs.h"
  13
  14 static int exfat_cont_expand(struct inode *inode, loff_t size)
  15 {
  16         struct address_space *mapping = inode->i_mapping;
  17         loff_t start = i_size_read(inode), count = size - i_size_read(inode);
  18         int err, err2;
  19
  20         err = generic_cont_expand_simple(inode, size);
  21         if (err)
  22                 return err;
  23
  24         inode->i_ctime = inode->i_mtime = current_time(inode);
  25         mark_inode_dirty(inode);
  26
  27         if (!IS_SYNC(inode))
  28                 return 0;
  29
  30         err = filemap_fdatawrite_range(mapping, start, start + count - 1);
  31         err2 = sync_mapping_buffers(mapping);
  32         if (!err)
  33                 err = err2;
  34         err2 = write_inode_now(inode, 1);
  35         if (!err)
  36                 err = err2;
  37         if (err)
  38                 return err;
  39
  40         return filemap_fdatawait_range(mapping, start, start + count - 1);
  41 }
  42
  43 static bool exfat_allow_set_time(struct exfat_sb_info *sbi, struct inode *inode)
  44 {
  45         mode_t allow_utime = sbi->options.allow_utime;
  46
  47         if (!uid_eq(current_fsuid(), inode->i_uid)) {
  48                 if (in_group_p(inode->i_gid))
  49                         allow_utime >>= 3;
  50                 if (allow_utime & MAY_WRITE)
  51                         return true;
  52         }
  53
  54         /* use a default check */
  55         return false;
  56 }
  57
  58 static int exfat_sanitize_mode(const struct exfat_sb_info *sbi,
  59                 struct inode *inode, umode_t *mode_ptr)
  60 {
  61         mode_t i_mode, mask, perm;
  62
  63         i_mode = inode->i_mode;
  64
  65         mask = (S_ISREG(i_mode) || S_ISLNK(i_mode)) ?
  66                 sbi->options.fs_fmask : sbi->options.fs_dmask;
  67         perm = *mode_ptr & ~(S_IFMT | mask);
  68
  69         /* Of the r and x bits, all (subject to umask) must be present.*/
  70         if ((perm & 0555) != (i_mode & 0555))
  71                 return -EPERM;
  72
  73         if (exfat_mode_can_hold_ro(inode)) {
  74                 /*
  75                  * Of the w bits, either all (subject to umask) or none must
  76                  * be present.
  77                  */
  78                 if ((perm & 0222) && ((perm & 0222) != (0222 & ~mask)))
  79                         return -EPERM;
  80         } else {
  81                 /*
  82                  * If exfat_mode_can_hold_ro(inode) is false, can't change
  83                  * w bits.
  84                  */
  85                 if ((perm & 0222) != (0222 & ~mask))
  86                         return -EPERM;
  87         }
  88
  89         *mode_ptr &= S_IFMT | perm;
  90
  91         return 0;
  92 }
  93
  94 /* resize the file length */
  95 int __exfat_truncate(struct inode *inode, loff_t new_size)
  96 {
  97         unsigned int num_clusters_new, num_clusters_phys;
  98         unsigned int last_clu = EXFAT_FREE_CLUSTER;
  99         struct exfat_chain clu;
 100         struct super_block *sb = inode->i_sb;
 101         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 102         struct exfat_inode_info *ei = EXFAT_I(inode);
 103         int evict = (ei->dir.dir == DIR_DELETED) ? 1 : 0;
 104
 105         /* check if the given file ID is opened */
 106         if (ei->type != TYPE_FILE && ei->type != TYPE_DIR)
 107                 return -EPERM;
 108
 109         exfat_set_volume_dirty(sb);
 110
 111         num_clusters_new = EXFAT_B_TO_CLU_ROUND_UP(i_size_read(inode), sbi);
 112         num_clusters_phys =
 113                 EXFAT_B_TO_CLU_ROUND_UP(EXFAT_I(inode)->i_size_ondisk, sbi);
 114
 115         exfat_chain_set(&clu, ei->start_clu, num_clusters_phys, ei->flags);
 116
 117         if (new_size > 0) {
 118                 /*
 119                  * Truncate FAT chain num_clusters after the first cluster
 120                  * num_clusters = min(new, phys);
 121                  */
 122                 unsigned int num_clusters =
 123                         min(num_clusters_new, num_clusters_phys);
 124
 125                 /*
 126                  * Follow FAT chain
 127                  * (defensive coding - works fine even with corrupted FAT table
 128                  */
 129                 if (clu.flags == ALLOC_NO_FAT_CHAIN) {
 130                         clu.dir += num_clusters;
 131                         clu.size -= num_clusters;
 132                 } else {
 133                         while (num_clusters > 0) {
 134                                 last_clu = clu.dir;
 135                                 if (exfat_get_next_cluster(sb, &(clu.dir)))
 136                                         return -EIO;
 137
 138                                 num_clusters--;
 139                                 clu.size--;
 140                         }
 141                 }
 142         } else {
 143                 ei->flags = ALLOC_NO_FAT_CHAIN;
 144                 ei->start_clu = EXFAT_EOF_CLUSTER;
 145         }
 146
 147         i_size_write(inode, new_size);
 148
 149         if (ei->type == TYPE_FILE)
 150                 ei->attr |= ATTR_ARCHIVE;
 151
 152         /* update the directory entry */
 153         if (!evict) {
 154                 struct timespec64 ts;
 155                 struct exfat_dentry *ep, *ep2;
 156                 struct exfat_entry_set_cache *es;
 157                 int err;
 158
 159                 es = exfat_get_dentry_set(sb, &(ei->dir), ei->entry,
 160                                 ES_ALL_ENTRIES);
 161                 if (!es)
 162                         return -EIO;
 163                 ep = exfat_get_dentry_cached(es, 0);
 164                 ep2 = exfat_get_dentry_cached(es, 1);
 165
 166                 ts = current_time(inode);
 167                 exfat_set_entry_time(sbi, &ts,
 168                                 &ep->dentry.file.modify_tz,
 169                                 &ep->dentry.file.modify_time,
 170                                 &ep->dentry.file.modify_date,
 171                                 &ep->dentry.file.modify_time_cs);
 172                 ep->dentry.file.attr = cpu_to_le16(ei->attr);
 173
 174                 /* File size should be zero if there is no cluster allocated */
 175                 if (ei->start_clu == EXFAT_EOF_CLUSTER) {
 176                         ep2->dentry.stream.valid_size = 0;
 177                         ep2->dentry.stream.size = 0;
 178                 } else {
 179                         ep2->dentry.stream.valid_size = cpu_to_le64(new_size);
 180                         ep2->dentry.stream.size = ep2->dentry.stream.valid_size;
 181                 }
 182
 183                 if (new_size == 0) {
 184                         /* Any directory can not be truncated to zero */
 185                         WARN_ON(ei->type != TYPE_FILE);
 186
 187                         ep2->dentry.stream.flags = ALLOC_FAT_CHAIN;
 188                         ep2->dentry.stream.start_clu = EXFAT_FREE_CLUSTER;
 189                 }
 190
 191                 exfat_update_dir_chksum_with_entry_set(es);
 192                 err = exfat_free_dentry_set(es, inode_needs_sync(inode));
 193                 if (err)
 194                         return err;
 195         }
 196
 197         /* cut off from the FAT chain */
 198         if (ei->flags == ALLOC_FAT_CHAIN && last_clu != EXFAT_FREE_CLUSTER &&
 199                         last_clu != EXFAT_EOF_CLUSTER) {
 200                 if (exfat_ent_set(sb, last_clu, EXFAT_EOF_CLUSTER))
 201                         return -EIO;
 202         }
 203
 204         /* invalidate cache and free the clusters */
 205         /* clear exfat cache */
 206         exfat_cache_inval_inode(inode);
 207
 208         /* hint information */
 209         ei->hint_bmap.off = EXFAT_EOF_CLUSTER;
 210         ei->hint_bmap.clu = EXFAT_EOF_CLUSTER;
 211
 212         /* hint_stat will be used if this is directory. */
 213         ei->hint_stat.eidx = 0;
 214         ei->hint_stat.clu = ei->start_clu;
 215         ei->hint_femp.eidx = EXFAT_HINT_NONE;
 216
 217         /* free the clusters */
 218         if (exfat_free_cluster(inode, &clu))
 219                 return -EIO;
 220
 221         exfat_clear_volume_dirty(sb);
 222
 223         return 0;
 224 }
 225
 226 void exfat_truncate(struct inode *inode, loff_t size)
 227 {
 228         struct super_block *sb = inode->i_sb;
 229         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 230         unsigned int blocksize = i_blocksize(inode);
 231         loff_t aligned_size;
 232         int err;
 233
 234         mutex_lock(&sbi->s_lock);
 235         if (EXFAT_I(inode)->start_clu == 0) {
 236                 /*
 237                  * Empty start_clu != ~0 (not allocated)
 238                  */
 239                 exfat_fs_error(sb, "tried to truncate zeroed cluster.");
 240                 goto write_size;
 241         }
 242
 243         err = __exfat_truncate(inode, i_size_read(inode));
 244         if (err)
 245                 goto write_size;
 246
 247         inode->i_ctime = inode->i_mtime = current_time(inode);
 248         if (IS_DIRSYNC(inode))
 249                 exfat_sync_inode(inode);
 250         else
 251                 mark_inode_dirty(inode);
 252
 253         inode->i_blocks = ((i_size_read(inode) + (sbi->cluster_size - 1)) &
 254                         ~(sbi->cluster_size - 1)) >> inode->i_blkbits;
 255 write_size:
 256         aligned_size = i_size_read(inode);
 257         if (aligned_size & (blocksize - 1)) {
 258                 aligned_size |= (blocksize - 1);
 259                 aligned_size++;
 260         }
 261
 262         if (EXFAT_I(inode)->i_size_ondisk > i_size_read(inode))
 263                 EXFAT_I(inode)->i_size_ondisk = aligned_size;
 264
 265         if (EXFAT_I(inode)->i_size_aligned > i_size_read(inode))
 266                 EXFAT_I(inode)->i_size_aligned = aligned_size;
 267         mutex_unlock(&sbi->s_lock);
 268 }
 269
 270 int exfat_getattr(struct user_namespace *mnt_uerns, const struct path *path,
 271                   struct kstat *stat, unsigned int request_mask,
 272                   unsigned int query_flags)
 273 {
 274         struct inode *inode = d_backing_inode(path->dentry);
 275         struct exfat_inode_info *ei = EXFAT_I(inode);
 276
 277         generic_fillattr(&init_user_ns, inode, stat);
 278         exfat_truncate_atime(&stat->atime);
 279         stat->result_mask |= STATX_BTIME;
 280         stat->btime.tv_sec = ei->i_crtime.tv_sec;
 281         stat->btime.tv_nsec = ei->i_crtime.tv_nsec;
 282         stat->blksize = EXFAT_SB(inode->i_sb)->cluster_size;
 283         return 0;
 284 }
 285
 286 int exfat_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 287                   struct iattr *attr)
 288 {
 289         struct exfat_sb_info *sbi = EXFAT_SB(dentry->d_sb);
 290         struct inode *inode = dentry->d_inode;
 291         unsigned int ia_valid;
 292         int error;
 293
 294         if ((attr->ia_valid & ATTR_SIZE) &&
 295             attr->ia_size > i_size_read(inode)) {
 296                 error = exfat_cont_expand(inode, attr->ia_size);
 297                 if (error || attr->ia_valid == ATTR_SIZE)
 298                         return error;
 299                 attr->ia_valid &= ~ATTR_SIZE;
 300         }
 301
 302         /* Check for setting the inode time. */
 303         ia_valid = attr->ia_valid;
 304         if ((ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) &&
 305             exfat_allow_set_time(sbi, inode)) {
 306                 attr->ia_valid &= ~(ATTR_MTIME_SET | ATTR_ATIME_SET |
 307                                 ATTR_TIMES_SET);
 308         }
 309
 310         error = setattr_prepare(&init_user_ns, dentry, attr);
 311         attr->ia_valid = ia_valid;
 312         if (error)
 313                 goto out;
 314
 315         if (((attr->ia_valid & ATTR_UID) &&
 316              !uid_eq(attr->ia_uid, sbi->options.fs_uid)) ||
 317             ((attr->ia_valid & ATTR_GID) &&
 318              !gid_eq(attr->ia_gid, sbi->options.fs_gid)) ||
 319             ((attr->ia_valid & ATTR_MODE) &&
 320              (attr->ia_mode & ~(S_IFREG | S_IFLNK | S_IFDIR | 0777)))) {
 321                 error = -EPERM;
 322                 goto out;
 323         }
 324
 325         /*
 326          * We don't return -EPERM here. Yes, strange, but this is too
 327          * old behavior.
 328          */
 329         if (attr->ia_valid & ATTR_MODE) {
 330                 if (exfat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
 331                         attr->ia_valid &= ~ATTR_MODE;
 332         }
 333
 334         if (attr->ia_valid & ATTR_SIZE) {
 335                 error = exfat_block_truncate_page(inode, attr->ia_size);
 336                 if (error)
 337                         goto out;
 338
 339                 down_write(&EXFAT_I(inode)->truncate_lock);
 340                 truncate_setsize(inode, attr->ia_size);
 341                 exfat_truncate(inode, attr->ia_size);
 342                 up_write(&EXFAT_I(inode)->truncate_lock);
 343         }
 344
 345         setattr_copy(&init_user_ns, inode, attr);
 346         exfat_truncate_atime(&inode->i_atime);
 347         mark_inode_dirty(inode);
 348
 349 out:
 350         return error;
 351 }
 352
 353 int exfat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
 354 {
 355         struct inode *inode = filp->f_mapping->host;
 356         int err;
 357
 358         err = __generic_file_fsync(filp, start, end, datasync);
 359         if (err)
 360                 return err;
 361
 362         err = sync_blockdev(inode->i_sb->s_bdev);
 363         if (err)
 364                 return err;
 365
 366         return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL);
 367 }
 368
 369 const struct file_operations exfat_file_operations = {
 370         .llseek         = generic_file_llseek,
 371         .read_iter      = generic_file_read_iter,
 372         .write_iter     = generic_file_write_iter,
 373         .mmap           = generic_file_mmap,
 374         .fsync          = exfat_file_fsync,
 375         .splice_read    = generic_file_splice_read,
 376         .splice_write   = iter_file_splice_write,
 377 };
 378
 379 const struct inode_operations exfat_file_inode_operations = {
 380         .setattr     = exfat_setattr,
 381         .getattr     = exfat_getattr,
 382 };