fs: move fiemap range validation into the file systems instances

Replace fiemap_check_flags with a fiemap_prep helper that also takes the inode and mapped range, and performs the sanity check and truncation previously done in fiemap_check_range. This way the validation is inside the file system itself and thus properly works for the stacked overlayfs case as well. Signed-off-by: Christoph Hellwig <[email protected]> Reviewed-by: Amir Goldstein <[email protected]> Reviewed-by: Darrick J. Wong <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Theodore Ts'o <[email protected]>
torvalds · Jun 4, 2020 · cddf8a2 · cddf8a2
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commit cddf8a2
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Showing 10 changed files with 47 additions and 54 deletions.
diff --git a/Documentation/filesystems/fiemap.txt b/Documentation/filesystems/fiemap.txt
@@ -203,16 +203,18 @@ EINTR once fatal signal received.
 
 
 Flag checking should be done at the beginning of the ->fiemap callback via the
-fiemap_check_flags() helper:
+fiemap_prep() helper:
 
-int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags);
+int fiemap_prep(struct inode *inode, struct fiemap_extent_info *fieinfo,
+ u64 start, u64 *len, u32 supported_flags);
 
 The struct fieinfo should be passed in as received from ioctl_fiemap(). The
 set of fiemap flags which the fs understands should be passed via fs_flags. If
-fiemap_check_flags finds invalid user flags, it will place the bad values in
+fiemap_prep finds invalid user flags, it will place the bad values in
 fieinfo->fi_flags and return -EBADR. If the file system gets -EBADR, from
-fiemap_check_flags(), it should immediately exit, returning that error back to
-ioctl_fiemap().
+fiemap_prep(), it should immediately exit, returning that error back to
+ioctl_fiemap(). Additionally the range is validate against the supported
+maximum file size.
 
 
 For each extent in the request range, the file system should call

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
@@ -8250,7 +8250,7 @@ static int btrfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 {
  int ret;
 
- ret = fiemap_check_flags(fieinfo, BTRFS_FIEMAP_FLAGS);
+ ret = fiemap_prep(inode, fieinfo, start, &len, BTRFS_FIEMAP_FLAGS);
  if (ret)
  return ret;
 

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
@@ -3408,8 +3408,10 @@ static int smb3_fiemap(struct cifs_tcon *tcon,
  int i, num, rc, flags, last_blob;
  u64 next;
 
- if (fiemap_check_flags(fei, FIEMAP_FLAG_SYNC))
- return -EBADR;
+ rc = fiemap_prep(d_inode(cfile->dentry), fei, start, &len,
+ FIEMAP_FLAG_SYNC);
+ if (rc)
+ return rc;
 
  xid = get_xid();
  again:

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
@@ -4938,8 +4938,9 @@ int ext4_get_es_cache(struct inode *inode, struct fiemap_extent_info *fieinfo,
  fieinfo->fi_flags &= ~FIEMAP_FLAG_CACHE;
  }
 
- if (fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC))
- return -EBADR;
+ error = fiemap_prep(inode, fieinfo, start, &len, FIEMAP_FLAG_SYNC);
+ if (error)
+ return error;
 
  error = ext4_fiemap_check_ranges(inode, start, &len);
  if (error)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
@@ -1825,7 +1825,8 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
  return ret;
  }
 
- ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC | FIEMAP_FLAG_XATTR);
+ ret = fiemap_prep(inode, fieinfo, start, &len,
+ FIEMAP_FLAG_SYNC | FIEMAP_FLAG_XATTR);
  if (ret)
  return ret;
 

diff --git a/fs/ioctl.c b/fs/ioctl.c
@@ -149,61 +149,50 @@ int fiemap_fill_next_extent(struct fiemap_extent_info *fieinfo, u64 logical,
 EXPORT_SYMBOL(fiemap_fill_next_extent);
 
 /**
- * fiemap_check_flags - check validity of requested flags for fiemap
+ * fiemap_prep - check validity of requested flags for fiemap
+ * @inode: Inode to operate on
  * @fieinfo: Fiemap context passed into ->fiemap
- * @fs_flags: Set of fiemap flags that the file system understands
+ * @start: Start of the mapped range
+ * @len: Length of the mapped range, can be truncated by this function.
+ * @supported_flags: Set of fiemap flags that the file system understands
  *
- * Called from file system ->fiemap callback. This will compute the
- * intersection of valid fiemap flags and those that the fs supports. That
- * value is then compared against the user supplied flags. In case of bad user
- * flags, the invalid values will be written into the fieinfo structure, and
- * -EBADR is returned, which tells ioctl_fiemap() to return those values to
- * userspace. For this reason, a return code of -EBADR should be preserved.
+ * This function must be called from each ->fiemap instance to validate the
+ * fiemap request against the file system parameters.
  *
- * Returns 0 on success, -EBADR on bad flags.
+ * Returns 0 on success, or a negative error on failure.
  */
-int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags)
+int fiemap_prep(struct inode *inode, struct fiemap_extent_info *fieinfo,
+ u64 start, u64 *len, u32 supported_flags)
 {
+ u64 maxbytes = inode->i_sb->s_maxbytes;
  u32 incompat_flags;
 
- incompat_flags = fieinfo->fi_flags & ~(FIEMAP_FLAGS_COMPAT & fs_flags);
- if (incompat_flags) {
- fieinfo->fi_flags = incompat_flags;
- return -EBADR;
- }
- return 0;
-}
-EXPORT_SYMBOL(fiemap_check_flags);
-
-static int fiemap_check_ranges(struct super_block *sb,
- u64 start, u64 len, u64 *new_len)
-{
- u64 maxbytes = (u64) sb->s_maxbytes;
-
- *new_len = len;
-
- if (len == 0)
+ if (*len == 0)
  return -EINVAL;
-
  if (start > maxbytes)
  return -EFBIG;
 
  /*
  * Shrink request scope to what the fs can actually handle.
  */
- if (len > maxbytes || (maxbytes - len) < start)
- *new_len = maxbytes - start;
+ if (*len > maxbytes || (maxbytes - *len) < start)
+ *len = maxbytes - start;
 
+ supported_flags &= FIEMAP_FLAGS_COMPAT;
+ incompat_flags = fieinfo->fi_flags & ~supported_flags;
+ if (incompat_flags) {
+ fieinfo->fi_flags = incompat_flags;
+ return -EBADR;
+ }
  return 0;
 }
+EXPORT_SYMBOL(fiemap_prep);
 
 static int ioctl_fiemap(struct file *filp, struct fiemap __user *ufiemap)
 {
  struct fiemap fiemap;
  struct fiemap_extent_info fieinfo = { 0, };
  struct inode *inode = file_inode(filp);
- struct super_block *sb = inode->i_sb;
- u64 len;
  int error;
 
  if (!inode->i_op->fiemap)
@@ -215,11 +204,6 @@ static int ioctl_fiemap(struct file *filp, struct fiemap __user *ufiemap)
  if (fiemap.fm_extent_count > FIEMAP_MAX_EXTENTS)
  return -EINVAL;
 
- error = fiemap_check_ranges(sb, fiemap.fm_start, fiemap.fm_length,
- &len);
- if (error)
- return error;
-
  fieinfo.fi_flags = fiemap.fm_flags;
  fieinfo.fi_extents_max = fiemap.fm_extent_count;
  fieinfo.fi_extents_start = ufiemap->fm_extents;
@@ -232,7 +216,8 @@ static int ioctl_fiemap(struct file *filp, struct fiemap __user *ufiemap)
  if (fieinfo.fi_flags & FIEMAP_FLAG_SYNC)
  filemap_write_and_wait(inode->i_mapping);
 
- error = inode->i_op->fiemap(inode, &fieinfo, fiemap.fm_start, len);
+ error = inode->i_op->fiemap(inode, &fieinfo, fiemap.fm_start,
+ fiemap.fm_length);
  fiemap.fm_flags = fieinfo.fi_flags;
  fiemap.fm_mapped_extents = fieinfo.fi_extents_mapped;
  if (copy_to_user(ufiemap, &fiemap, sizeof(fiemap)))
@@ -320,7 +305,7 @@ static int __generic_block_fiemap(struct inode *inode,
  bool past_eof = false, whole_file = false;
  int ret = 0;
 
- ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC);
+ ret = fiemap_prep(inode, fieinfo, start, &len, FIEMAP_FLAG_SYNC);
  if (ret)
  return ret;
 

diff --git a/fs/iomap/fiemap.c b/fs/iomap/fiemap.c
@@ -75,7 +75,7 @@ int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi,
  ctx.fi = fi;
  ctx.prev.type = IOMAP_HOLE;
 
- ret = fiemap_check_flags(fi, FIEMAP_FLAG_SYNC);
+ ret = fiemap_prep(inode, fi, start, &len, FIEMAP_FLAG_SYNC);
  if (ret)
  return ret;
 

diff --git a/fs/nilfs2/inode.c b/fs/nilfs2/inode.c
@@ -1006,7 +1006,7 @@ int nilfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
  unsigned int blkbits = inode->i_blkbits;
  int ret, n;
 
- ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC);
+ ret = fiemap_prep(inode, fieinfo, start, &len, FIEMAP_FLAG_SYNC);
  if (ret)
  return ret;
 

diff --git a/fs/ocfs2/extent_map.c b/fs/ocfs2/extent_map.c
@@ -746,7 +746,8 @@ int ocfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
  struct buffer_head *di_bh = NULL;
  struct ocfs2_extent_rec rec;
 
- ret = fiemap_check_flags(fieinfo, OCFS2_FIEMAP_FLAGS);
+ ret = fiemap_prep(inode, fieinfo, map_start, &map_len,
+ OCFS2_FIEMAP_FLAGS);
  if (ret)
  return ret;
 

diff --git a/include/linux/fiemap.h b/include/linux/fiemap.h
@@ -13,9 +13,10 @@ struct fiemap_extent_info {
  fiemap_extent array */
 };
 
+int fiemap_prep(struct inode *inode, struct fiemap_extent_info *fieinfo,
+ u64 start, u64 *len, u32 supported_flags);
 int fiemap_fill_next_extent(struct fiemap_extent_info *info, u64 logical,
  u64 phys, u64 len, u32 flags);
-int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags);
 
 int generic_block_fiemap(struct inode *inode,
  struct fiemap_extent_info *fieinfo, u64 start, u64 len,