Bug 1511560 - Move syscalls for adjusting memory mapping properties into SandboxPolicyCommon. r=gcp

madvise is used by our malloc (and probably others), and mprotect is
used with shared memory, including when created by another process, so
the common policy should include those rules.

Depends on D14521

Differential Revision: https://phabricator.services.mozilla.com/D14522

--HG--
extra : moz-landing-system : lando

security/sandbox/linux/SandboxFilter.cpp

@@ -447,7 +447,24 @@ class SandboxPolicyCommon : public SandboxPolicyBase {
       case __NR_munmap:
         return Allow();
 
-        // Signal handling
+        // ipc::Shmem; also, glibc when creating threads:
+      case __NR_mprotect:
+        return Allow();
+
+        // madvise hints used by malloc; see bug 1303813 and bug 1364533
+      case __NR_madvise: {
+        Arg<int> advice(2);
+        return If(advice == MADV_DONTNEED, Allow())
+            .ElseIf(advice == MADV_FREE, Allow())
+            .ElseIf(advice == MADV_HUGEPAGE, Allow())
+            .ElseIf(advice == MADV_NOHUGEPAGE, Allow())
+#ifdef MOZ_ASAN
+            .ElseIf(advice == MADV_DONTDUMP, Allow())
+#endif
+            .Else(InvalidSyscall());
+      }
+
+      // Signal handling
 #if defined(ANDROID) || defined(MOZ_ASAN)
       case __NR_sigaltstack:
 #endif
@@ -1052,8 +1069,9 @@ class ContentSandboxPolicy : public SandboxPolicyCommon {
             .Default(SandboxPolicyCommon::EvaluateSyscall(sysno));
       }
 
-      case __NR_mprotect:
       case __NR_brk:
+        // FIXME(bug 1510861) are we using any hints that aren't allowed
+        // in SandboxPolicyCommon now?
       case __NR_madvise:
         // libc's realloc uses mremap (Bug 1286119); wasm does too (bug
         // 1342385).
@@ -1335,20 +1353,6 @@ class GMPSandboxPolicy : public SandboxPolicyCommon {
       case __NR_openat:
         return Trap(OpenTrap, mFiles);
 
-        // ipc::Shmem
-      case __NR_mprotect:
-        return Allow();
-      case __NR_madvise: {
-        Arg<int> advice(2);
-        return If(advice == MADV_DONTNEED, Allow())
-            .ElseIf(advice == MADV_FREE, Allow())
-            .ElseIf(advice == MADV_HUGEPAGE, Allow())
-            .ElseIf(advice == MADV_NOHUGEPAGE, Allow())
-#  ifdef MOZ_ASAN
-            .ElseIf(advice == MADV_DONTDUMP, Allow())
-#  endif
-            .Else(InvalidSyscall());
-      }
       case __NR_brk:
       CASES_FOR_geteuid:
         return Allow();