[Xen-devel] [RFC PATCH 32/60] hyper_dmabuf: make all shared pages read-only

[Dongwon Kim <dongwon.kim@xxxxxxxxx>]

All shared pages need to be read-only from importer's
point of view to prevent the buffer from being corrupted.

This patch may need to be reverted if we find a better
way to protect the original content in this sharing
model.

Signed-off-by: Dongwon Kim <dongwon.kim@xxxxxxxxx>
---
 drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_shm.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_shm.c 
b/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_shm.c
index c6a2993..1416a69 100644
--- a/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_shm.c
+++ b/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_shm.c
@@ -104,24 +104,24 @@ int hyper_dmabuf_xen_share_pages(struct page **pages, int 
domid, int nents,
 
        *refs_info = (void *)sh_pages_info;
 
-       /* share data pages in rw mode*/
+       /* share data pages in readonly mode for security */
        for (i=0; i<nents; i++) {
                lvl2_table[i] = gnttab_grant_foreign_access(domid,
                                                            
pfn_to_mfn(page_to_pfn(pages[i])),
-                                                           0);
+                                                           true /* read-only 
from remote domain */);
        }
 
        /* Share 2nd level addressing pages in readonly mode*/
        for (i=0; i< n_lvl2_grefs; i++) {
                lvl3_table[i] = gnttab_grant_foreign_access(domid,
                                                            
virt_to_mfn((unsigned long)lvl2_table+i*PAGE_SIZE ),
-                                                           1);
+                                                           true);
        }
 
        /* Share lvl3_table in readonly mode*/
        lvl3_gref = gnttab_grant_foreign_access(domid,
                                                virt_to_mfn((unsigned 
long)lvl3_table),
-                                               1);
+                                               true);
 
 
        /* Store lvl3_table page to be freed later */
@@ -317,12 +317,12 @@ struct page ** hyper_dmabuf_xen_map_shared_pages(int 
lvl3_gref, int domid, int n
                for (j = 0; j < REFS_PER_PAGE; j++) {
                        gnttab_set_map_op(&data_map_ops[k],
                                          (unsigned 
long)pfn_to_kaddr(page_to_pfn(data_pages[k])),
-                                         GNTMAP_host_map,
+                                         GNTMAP_host_map | GNTMAP_readonly,
                                          lvl2_table[j], domid);
 
                        gnttab_set_unmap_op(&data_unmap_ops[k],
                                            (unsigned 
long)pfn_to_kaddr(page_to_pfn(data_pages[k])),
-                                           GNTMAP_host_map, -1);
+                                           GNTMAP_host_map | GNTMAP_readonly, 
-1);
                        k++;
                }
        }
@@ -333,12 +333,12 @@ struct page ** hyper_dmabuf_xen_map_shared_pages(int 
lvl3_gref, int domid, int n
        for (j = 0; j < nents_last; j++) {
                gnttab_set_map_op(&data_map_ops[k],
                                  (unsigned 
long)pfn_to_kaddr(page_to_pfn(data_pages[k])),
-                                 GNTMAP_host_map,
+                                 GNTMAP_host_map | GNTMAP_readonly,
                                  lvl2_table[j], domid);
 
                gnttab_set_unmap_op(&data_unmap_ops[k],
                                    (unsigned 
long)pfn_to_kaddr(page_to_pfn(data_pages[k])),
-                                   GNTMAP_host_map, -1);
+                                   GNTMAP_host_map | GNTMAP_readonly, -1);
                k++;
        }
 
-- 
2.7.4


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel