[PATCH v17 24/34] pc-bios/s390-ccw: Add signed component address overlap checks

Add address range tracking and overlap checks to ensure that no
component overlaps with a signed component during secure IPL.

Signed-off-by: Zhuoying Cai <[email protected]>
Reviewed-by: Jared Rossi <[email protected]>
Reviewed-by: Matthew Rosato <[email protected]>
Reviewed-by: Collin Walling <[email protected]>
---
 pc-bios/s390-ccw/secure-ipl.c | 19 +++++++++++++++++++
 pc-bios/s390-ccw/secure-ipl.h | 10 ++++++++++
 2 files changed, 29 insertions(+)

diff --git a/pc-bios/s390-ccw/secure-ipl.c b/pc-bios/s390-ccw/secure-ipl.c
index a03105cf5a..fd3455cf67 100644
--- a/pc-bios/s390-ccw/secure-ipl.c
+++ b/pc-bios/s390-ccw/secure-ipl.c
@@ -193,6 +193,23 @@ static void init_lists(IplDeviceComponentList *comp_list,
     cert_list->ipl_info_header.len = sizeof(IplInfoBlockHeader);
 }
 
+static void check_comp_overlap(IplDeviceComponentList *comp_list,
+                               IplDeviceComponentEntry comp_entry)
+{
+    IplDeviceComponentEntry *comp;
+
+    /*
+     * Check component's address range does not overlap with any
+     * signed component's address range.
+     */
+    for_each_rb_entry(comp, comp_list) {
+        if (comp->flags & S390_IPL_DEV_COMP_FLAG_SC &&
+            intersects(comp->addr, comp->len, comp_entry.addr, comp_entry.len)) {
+            zipl_secure_error("Component addresses overlap");
+        }
+    }
+}
+
 static int zipl_load_signature(ComponentEntry *entry, uint64_t sig)
 {
     if (entry->compdat.sig_info.format != DER_SIGNATURE_FORMAT) {
@@ -294,6 +311,8 @@ int zipl_run_secure(ComponentEntry **entry_ptr, const uint8_t *tmp_sec,
             comp_entry.addr = comp_addr;
             comp_entry.len = (uint64_t)comp_len;
 
+            check_comp_overlap(comp_list, comp_entry);
+
             /* no signature present (unsigned component) */
             if (!sig_entry.len) {
                 comp_list_add(comp_list, comp_entry);
diff --git a/pc-bios/s390-ccw/secure-ipl.h b/pc-bios/s390-ccw/secure-ipl.h
index b5a871a799..d495dd5d04 100644
--- a/pc-bios/s390-ccw/secure-ipl.h
+++ b/pc-bios/s390-ccw/secure-ipl.h
@@ -116,4 +116,14 @@ static inline bool verify_signature(IplDeviceComponentEntry comp_entry,
     return false;
 }
 
+static inline bool intersects(uint64_t addr0, uint64_t size0,
+                              uint64_t addr1, uint64_t size1)
+{
+    if (addr1 > addr0) {
+        return addr1 - addr0 < size0;
+    }
+
+    return addr0 - addr1 < size1;
+}
+
 #endif /* _PC_BIOS_S390_CCW_SECURE_IPL_H */
-- 
2.55.0