[PATCH v2 2/2] virtiofs: allow skipping abort interface

[Xie Yongji <xieyongji@xxxxxxxxxxxxx>]

Virtio-fs does not support aborting requests which are being
processed. Otherwise, it might trigger UAF since
virtio_fs_request_complete() doesn't know the requests are
aborted. So let's remove the abort interface.

Fixes: 15c8e72e88e0 ("fuse: allow skipping control interface and forced unmount")
Signed-off-by: Xie Yongji <xieyongji@xxxxxxxxxxxxx>
---
 fs/fuse/control.c   | 4 ++--
 fs/fuse/fuse_i.h    | 4 ++++
 fs/fuse/inode.c     | 1 +
 fs/fuse/virtio_fs.c | 1 +
 4 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/fs/fuse/control.c b/fs/fuse/control.c
index 7cede9a3bc96..d93d8ea3a090 100644
--- a/fs/fuse/control.c
+++ b/fs/fuse/control.c
@@ -272,8 +272,8 @@ int fuse_ctl_add_conn(struct fuse_conn *fc)
 
 	if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400, 1,
 				 NULL, &fuse_ctl_waiting_ops) ||
-	    !fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200, 1,
-				 NULL, &fuse_ctl_abort_ops) ||
+	    (!fc->no_abort_control && !fuse_ctl_add_dentry(parent, fc, "abort",
+			S_IFREG | 0200, 1, NULL, &fuse_ctl_abort_ops)) ||
 	    !fuse_ctl_add_dentry(parent, fc, "max_background", S_IFREG | 0600,
 				 1, NULL, &fuse_conn_max_background_ops) ||
 	    !fuse_ctl_add_dentry(parent, fc, "congestion_threshold",
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index a47f14d0ee3f..e29a4e2f2b35 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -507,6 +507,7 @@ struct fuse_fs_context {
 	bool default_permissions:1;
 	bool allow_other:1;
 	bool destroy:1;
+	bool no_abort_control:1;
 	bool no_force_umount:1;
 	bool legacy_opts_show:1;
 	enum fuse_dax_mode dax_mode;
@@ -765,6 +766,9 @@ struct fuse_conn {
 	/* Delete dentries that have gone stale */
 	unsigned int delete_stale:1;
 
+	/** Do not create abort entry in fusectl fs */
+	unsigned int no_abort_control:1;
+
 	/** Do not allow MNT_FORCE umount */
 	unsigned int no_force_umount:1;
 
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 4059c6898e08..02a16cd35f42 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1564,6 +1564,7 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
 	fc->legacy_opts_show = ctx->legacy_opts_show;
 	fc->max_read = max_t(unsigned int, 4096, ctx->max_read);
 	fc->destroy = ctx->destroy;
+	fc->no_abort_control = ctx->no_abort_control;
 	fc->no_force_umount = ctx->no_force_umount;
 
 	err = -ENOMEM;
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 24bcf4dbca2a..af369bea6dbb 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -1287,6 +1287,7 @@ static inline void virtio_fs_ctx_set_defaults(struct fuse_fs_context *ctx)
 	ctx->max_read = UINT_MAX;
 	ctx->blksize = 512;
 	ctx->destroy = true;
+	ctx->no_abort_control = true;
 	ctx->no_force_umount = true;
 }
 
-- 
2.20.1