Bug 1664922 - Allow CPU information in the "utility" sandbox policy, for nsSystemInfo. r=gcp

Differential Revision: https://phabricator.services.mozilla.com/D90603

security/sandbox/linux/broker/SandboxBrokerPolicyFactory.cpp

@@ -683,6 +683,15 @@ SandboxBrokerPolicyFactory::GetUtilityPolicy(int aPid) {
 
   AddSharedMemoryPaths(policy.get(), aPid);
 
+  // FIXME (bug 1662321): we should fix nsSystemInfo so that every
+  // child process doesn't need to re-read these files to get the info
+  // the parent process already has.
+  policy->AddPath(rdonly, "/proc/cpuinfo");
+  policy->AddPath(rdonly,
+                  "/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq");
+  policy->AddPath(rdonly, "/sys/devices/system/cpu/cpu0/cache/index2/size");
+  policy->AddPath(rdonly, "/sys/devices/system/cpu/cpu0/cache/index3/size");
+
   if (policy->IsEmpty()) {
     policy = nullptr;
   }