[PATCH 44/52] fuse: Clear setuid bit even in direct I/O path

Vivek Goyal
2018-12-10T17:13:10Z

With cache=never, we fall back to direct IO. pjdfstest chmod test 12.t was
failing because if a file has setuid bit, it should be cleared if an
unpriviledged user opens it for write and writes to it.

Call fuse_remove_privs() even for direct I/O path.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
fs/fuse/file.c | 20 ++++++++++++++++----
1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index cb28cf26a6e7..0be5a7380b3c 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1679,13 +1679,25 @@ static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from)
/* Don't allow parallel writes to the same file */
inode_lock(inode);
res = generic_write_checks(iocb, from);
- if (res > 0)
- res = fuse_direct_io(&io, from, &iocb->ki_pos, FUSE_DIO_WRITE);
+ if (res < 0)
+ goto out_invalidate;
+
+ res = file_remove_privs(iocb->ki_filp);
+ if (res)
+ goto out_invalidate;
+
+ res = fuse_direct_io(&io, from, &iocb->ki_pos, FUSE_DIO_WRITE);
+ if (res < 0)
+ goto out_invalidate;
+
fuse_invalidate_attr(inode);
- if (res > 0)
- fuse_write_update_size(inode, iocb->ki_pos);
+ fuse_write_update_size(inode, iocb->ki_pos);
inode_unlock(inode);
+ return res;

+out_invalidate:
+ fuse_invalidate_attr(inode);
+ inode_unlock(inode);
return res;
}

--
2.13.6