sandbox: Fix RedirectToUserSpacePolicyWrapper

sandbox/linux/seccomp-bpf/sandbox_bpf.cc

Index: sandbox/linux/seccomp-bpf/sandbox_bpf.cc
diff --git a/sandbox/linux/seccomp-bpf/sandbox_bpf.cc b/sandbox/linux/seccomp-bpf/sandbox_bpf.cc
index 83b98a663f9235fc63c409fe13d1577ba8d938d0..d0f6620d8ec3af4c6e2c0f30279574bf94cbb160 100644
--- a/sandbox/linux/seccomp-bpf/sandbox_bpf.cc
+++ b/sandbox/linux/seccomp-bpf/sandbox_bpf.cc
@@ -199,9 +199,7 @@ class RedirectToUserSpacePolicyWrapper : public SandboxBPFPolicy {
                                     int system_call_number) const OVERRIDE {
     ErrorCode err =
         wrapped_policy_->EvaluateSyscall(sandbox_compiler, system_call_number);
-    if ((err.err() & SECCOMP_RET_ACTION) == SECCOMP_RET_ERRNO) {
-      return ReturnErrnoViaTrap(sandbox_compiler, err.err() & SECCOMP_RET_DATA);
-    }
+    ChangeErrnoToTraps(&err, sandbox_compiler);
     return err;
   }
 
@@ -215,6 +213,29 @@ class RedirectToUserSpacePolicyWrapper : public SandboxBPFPolicy {
     return sandbox_compiler->Trap(ReturnErrno, reinterpret_cast<void*>(err));
   }
 
+  // ChangeErrnoToTraps recursivly iterates through the ErrorCode
+  // converting any ERRNO to a userspace trap
+  void ChangeErrnoToTraps(ErrorCode* err, SandboxBPF* sandbox_compiler) const {
+    if (err->error_type() == ErrorCode::ET_SIMPLE &&
+        (err->err() & SECCOMP_RET_ACTION) == SECCOMP_RET_ERRNO) {
+      // Have an errno, need to change this to a trap
+      *err =
+          ReturnErrnoViaTrap(sandbox_compiler, err->err() & SECCOMP_RET_DATA);
+      return;
+    } else if (err->error_type() == ErrorCode::ET_COND) {
+      // Need to explore both paths
+      ChangeErrnoToTraps((ErrorCode*)err->passed(), sandbox_compiler);
+      ChangeErrnoToTraps((ErrorCode*)err->failed(), sandbox_compiler);
+      return;
+    } else if (err->error_type() == ErrorCode::ET_TRAP) {
+      return;
+    } else if (err->error_type() == ErrorCode::ET_SIMPLE &&
+               (err->err() & SECCOMP_RET_ACTION) == SECCOMP_RET_ALLOW) {
+      return;
+    }
+    NOTREACHED();
+  }
+
   const SandboxBPFPolicy* wrapped_policy_;
   DISALLOW_COPY_AND_ASSIGN(RedirectToUserSpacePolicyWrapper);
 };
@@ -1035,6 +1056,19 @@ ErrorCode SandboxBPF::UnsafeTrap(Trap::TrapFnc fnc, const void* aux) {
   return Trap::MakeTrap(fnc, aux, false /* Unsafe Trap */);
 }
 
+bool SandboxBPF::IsRequiredForUnsafeTrap(int sysno) {
+  return (sysno == __NR_rt_sigprocmask || sysno == __NR_rt_sigreturn
+#if defined(__NR_sigprocmask)
+          ||
+          sysno == __NR_sigprocmask
+#endif
+#if defined(__NR_sigreturn)
+          ||
+          sysno == __NR_sigreturn
+#endif
+          );
+}
+
 intptr_t SandboxBPF::ForwardSyscall(const struct arch_seccomp_data& args) {
   return Syscall::Call(args.nr,
                        static_cast<intptr_t>(args.args[0]),