xsm: Fix xsm_mmu_* and xsm_update_va_mapping hooks

This is an attempt to properly fix the hypervisor crash previously
described in
http://marc.info/?l=xen-devel&m=128396289707362&w=2

In looking into this issue, I think the proper fix is to move the
xsm_mmu_* and xsm_update_va_mapping hook calls later in the callers,
after more validation has been performed and the page_info struct is
readily available, and pass the page_info to the hooks. This patch
moves the xsm_mmu_normal_update, xsm_mmu_machphys_update and
xsm_update_va_mapping hook calls accordingly, and updates their
interfaces and hook function implementations.  This appears to resolve
the crashes for me.

Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>

2 files changed, 14 insertions, 38 deletions

diff --git a/xen/xsm/dummy.c b/xen/xsm/dummy.c
index 9716f941cf..bf07540ca5 100644
--- a/xen/xsm/dummy.c
+++ b/xen/xsm/dummy.c
@@ -405,19 +405,20 @@ static int dummy_domain_memory_map (struct domain *d)
     return 0;
 }
 
-static int dummy_mmu_normal_update (struct domain *d, struct domain *f, 
-                                                                intpte_t fpte)
+static int dummy_mmu_normal_update (struct domain *d,
+				    intpte_t fpte, struct page_info *page)
 {
     return 0;
 }
 
-static int dummy_mmu_machphys_update (struct domain *d, unsigned long mfn)
+static int dummy_mmu_machphys_update (struct domain *d, struct page_info *page)
 {
     return 0;
 }
 
-static int dummy_update_va_mapping (struct domain *d, struct domain *f, 
-                                                            l1_pgentry_t pte)
+static int dummy_update_va_mapping (struct domain *d,
+				    l1_pgentry_t pte,
+				    struct page_info *page)
 {
     return 0;
 }
diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c
index cb83b361ed..933873efd2 100644
--- a/xen/xsm/flask/hooks.c
+++ b/xen/xsm/flask/hooks.c
@@ -347,26 +347,6 @@ static int get_page_sid(struct page_info *page, u32 *sid)
     return rc;
 }
 
-static int get_mfn_sid(unsigned long mfn, u32 *sid)
-{
-    int rc = 0;
-    struct page_info *page;
-
-    if ( mfn_valid(mfn) )
-    {
-        /*mfn is valid if this is a page that Xen is tracking!*/
-        page = mfn_to_page(mfn);
-        rc = get_page_sid(page, sid);
-    }
-    else
-    {
-        /*Possibly an untracked IO page?*/
-        rc = security_iomem_sid(mfn, sid);
-    }
-
-    return rc;    
-}
-
 static int flask_memory_adjust_reservation(struct domain *d1, struct domain *d2)
 {
     return domain_has_perm(d1, d2, SECCLASS_MMU, MMU__ADJUST);
@@ -1006,12 +986,11 @@ static int flask_domain_memory_map(struct domain *d)
     return domain_has_perm(current->domain, d, SECCLASS_MMU, MMU__MEMORYMAP);
 }
 
-static int flask_mmu_normal_update(struct domain *d, struct domain *f, 
-                                   intpte_t fpte)
+static int flask_mmu_normal_update(struct domain *d, 
+                                   intpte_t fpte, struct page_info *page)
 {
     int rc = 0;
     u32 map_perms = MMU__MAP_READ;
-    unsigned long fmfn;
     struct domain_security_struct *dsec;
     u32 fsid;
 
@@ -1020,42 +999,38 @@ static int flask_mmu_normal_update(struct domain *d, struct domain *f,
     if ( l1e_get_flags(l1e_from_intpte(fpte)) & _PAGE_RW )
         map_perms |= MMU__MAP_WRITE;
 
-    fmfn = gmfn_to_mfn(f, l1e_get_pfn(l1e_from_intpte(fpte)));
-
-    rc = get_mfn_sid(fmfn, &fsid);
+    rc = get_page_sid(page, &fsid);
     if ( rc )
         return rc;
 
     return avc_has_perm(dsec->sid, fsid, SECCLASS_MMU, map_perms, NULL);
 }
 
-static int flask_mmu_machphys_update(struct domain *d, unsigned long mfn)
+static int flask_mmu_machphys_update(struct domain *d, struct page_info *page)
 {
     int rc = 0;
     u32 psid;
     struct domain_security_struct *dsec;
     dsec = d->ssid;
 
-    rc = get_mfn_sid(mfn, &psid);
+    rc = get_page_sid(page, &psid);
     if ( rc )
         return rc;
 
     return avc_has_perm(dsec->sid, psid, SECCLASS_MMU, MMU__UPDATEMP, NULL);
 }
 
-static int flask_update_va_mapping(struct domain *d, struct domain *f, 
-                                   l1_pgentry_t pte)
+static int flask_update_va_mapping(struct domain *d,
+                                   l1_pgentry_t pte, struct page_info *page)
 {
     int rc = 0;
     u32 psid;
     u32 map_perms = MMU__MAP_READ;
-    unsigned long mfn;
     struct domain_security_struct *dsec;
 
     dsec = d->ssid;
 
-    mfn = gmfn_to_mfn(f, l1e_get_pfn(pte));        
-    rc = get_mfn_sid(mfn, &psid);
+    rc = get_page_sid(page, &psid);
     if ( rc )
         return rc;