Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull misc vfs updates from Al Viro:
 "No common topic, really - a handful of assorted stuff; the least
  trivial bits are Mark's dedupe patches"

* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  fs/exofs: only use true/false for asignment of bool type variable
  fs/exofs: fix potential memory leak in mount option parsing
  Delete invalid assignment statements in do_sendfile
  iomap: remove duplicated include from iomap.c
  vfs: dedupe should return EPERM if permission is not granted
  vfs: allow dedupe of user owned read-only files
  ntfs: don't open-code ERR_CAST
  ext4: don't open-code ERR_CAST

1 files changed, 16 insertions, 3 deletions

diff --git a/fs/read_write.c b/fs/read_write.c
index 603794b207eb..5a2ee488c5d2 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1407,7 +1407,6 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
 		goto fput_in;
 	if (!(out.file->f_mode & FMODE_WRITE))
 		goto fput_out;
-	retval = -EINVAL;
 	in_inode = file_inode(in.file);
 	out_inode = file_inode(out.file);
 	out_pos = out.file->f_pos;
@@ -1977,6 +1976,20 @@ out_error:
 }
 EXPORT_SYMBOL(vfs_dedupe_file_range_compare);
 
+/* Check whether we are allowed to dedupe the destination file */
+static bool allow_file_dedupe(struct file *file)
+{
+	if (capable(CAP_SYS_ADMIN))
+		return true;
+	if (file->f_mode & FMODE_WRITE)
+		return true;
+	if (uid_eq(current_fsuid(), file_inode(file)->i_uid))
+		return true;
+	if (!inode_permission(file_inode(file), MAY_WRITE))
+		return true;
+	return false;
+}
+
 int vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
 			      struct file *dst_file, loff_t dst_pos, u64 len)
 {
@@ -1990,8 +2003,8 @@ int vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
 	if (ret < 0)
 		goto out_drop_write;
 
-	ret = -EINVAL;
-	if (!(capable(CAP_SYS_ADMIN) || (dst_file->f_mode & FMODE_WRITE)))
+	ret = -EPERM;
+	if (!allow_file_dedupe(dst_file))
 		goto out_drop_write;
 
 	ret = -EXDEV;