Allow the seccomp sandbox to be enabled, even if the suid sandbox has...

sandbox/linux/seccomp/madvise.cc

 #include "debug.h"
 #include "sandbox_impl.h"
 
 namespace playground {
 
 int Sandbox::sandbox_madvise(void* start, size_t length, int advice) {
   Debug::syscall(__NR_madvise, "Executing handler");
   struct {
     int       sysnum;
     long long cookie;
     MAdvise   madvise_req;
   } __attribute__((packed)) request;
   request.sysnum             = __NR_madvise;
   request.cookie             = cookie();
   request.madvise_req.start  = start;
   request.madvise_req.len    = length;
   request.madvise_req.advice = advice;
 
   long rc;
   SysCalls sys;
   if (write(sys, processFdPub(), &request, sizeof(request)) !=
       sizeof(request) ||
       read(sys, threadFdPub(), &rc, sizeof(rc)) != sizeof(rc)) {
     die("Failed to forward madvise() request [sandbox]");
   }
   return static_cast<int>(rc);
 }
 
-bool Sandbox::process_madvise(int parentProc, int sandboxFd, int threadFdPub,
+bool Sandbox::process_madvise(int parentMapsFd, int sandboxFd, int threadFdPub,
                               int threadFd, SecureMem::Args* mem) {
   // Read request
   MAdvise madvise_req;
   SysCalls sys;
   if (read(sys, sandboxFd, &madvise_req, sizeof(madvise_req)) !=
       sizeof(madvise_req)) {
     die("Failed to read parameters for madvise() [process]");
   }
   int rc = -EINVAL;
   switch (madvise_req.advice) {
@@ skipping 26 matching lines @@
         }
       }
 
       // Changing attributes on memory regions that were newly mapped inside of
       // the sandbox is OK.
       goto ok;
   }
 }
 
 } // namespace