Re: [PATCH 08/11] fs: move fiemap range validation into the file systems instances

Ritesh Harjani <riteshh@xxxxxxxxxxxxx> · Wed, 6 May 2020 09:46:52 +0530

On 5/5/20 9:13 PM, Christoph Hellwig wrote:
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 <hch@xxxxxx>
Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>

Looks ok. Please feel free to add:
Reviewed-by: Ritesh  Harjani <riteshh@xxxxxxxxxxxxx>


---
  Documentation/filesystems/fiemap.txt | 12 +++---
  fs/btrfs/inode.c                     |  2 +-
  fs/cifs/smb2ops.c                    |  6 ++-
  fs/ext4/extents.c                    |  5 ++-
  fs/f2fs/data.c                       |  3 +-
  fs/ioctl.c                           | 63 +++++++++++-----------------
  fs/iomap/fiemap.c                    |  2 +-
  fs/nilfs2/inode.c                    |  2 +-
  fs/ocfs2/extent_map.c                |  3 +-
  include/linux/fiemap.h               |  3 +-
  10 files changed, 47 insertions(+), 54 deletions(-)

diff --git a/Documentation/filesystems/fiemap.txt b/Documentation/filesystems/fiemap.txt
index ac87e6fda842b..35c8571eccb6e 100644
--- 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
index 320d1062068d3..1f1ec361089b3 100644
--- 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
index 09047f1ddfb66..828e53e795c6d 100644
--- 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
index a41ae7c510170..41f73dea92cac 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4908,8 +4908,9 @@ 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
index 25abbbb65ba09..03faafc591b17 100644
--- 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
index 3f300cc07dee4..56bbf02209aef 100644
--- 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
index 449705575acf9..89dca4a97e4a2 100644
--- 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
index 6e1aca38931f3..052c2da11e4d7 100644
--- 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
index e3e2d1b2af51a..3744179b73fa1 100644
--- 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
index 240d4f7d9116a..4e624c4665837 100644
--- 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,







