Reland: Introduce sys_sigprocmask and sys_sigaction. (patchset #4 id:80001 of https://codereview.ch…

sandbox/linux/seccomp-bpf/trap.cc

Index: sandbox/linux/seccomp-bpf/trap.cc
diff --git a/sandbox/linux/seccomp-bpf/trap.cc b/sandbox/linux/seccomp-bpf/trap.cc
index 145e62469cacca37c07aa40916c1d27795082c11..79b756952961b24b54260c09911071bb74a02ddd 100644
--- a/sandbox/linux/seccomp-bpf/trap.cc
+++ b/sandbox/linux/seccomp-bpf/trap.cc
@@ -17,12 +17,9 @@
 #include "sandbox/linux/bpf_dsl/seccomp_macros.h"
 #include "sandbox/linux/seccomp-bpf/die.h"
 #include "sandbox/linux/seccomp-bpf/syscall.h"
+#include "sandbox/linux/services/syscall_wrappers.h"
 #include "sandbox/linux/system_headers/linux_seccomp.h"
-
-// Android's signal.h doesn't define ucontext etc.
-#if defined(OS_ANDROID)
-#include "sandbox/linux/system_headers/android_ucontext.h"
-#endif
+#include "sandbox/linux/system_headers/linux_signal.h"
 
 namespace {
 
@@ -53,13 +50,13 @@ const char kSandboxDebuggingEnv[] = "CHROME_SANDBOX_DEBUGGING";
 // possibly even worse.
 bool GetIsInSigHandler(const ucontext_t* ctx) {
   // Note: on Android, sigismember does not take a pointer to const.
-  return sigismember(const_cast<sigset_t*>(&ctx->uc_sigmask), SIGBUS);
+  return sigismember(const_cast<sigset_t*>(&ctx->uc_sigmask), LINUX_SIGBUS);
 }
 
 void SetIsInSigHandler() {
   sigset_t mask;
-  if (sigemptyset(&mask) || sigaddset(&mask, SIGBUS) ||
-      sigprocmask(SIG_BLOCK, &mask, NULL)) {
+  if (sigemptyset(&mask) || sigaddset(&mask, LINUX_SIGBUS) ||
+      sandbox::sys_sigprocmask(LINUX_SIG_BLOCK, &mask, NULL)) {
     SANDBOX_DIE("Failed to block SIGBUS");
   }
 }
@@ -82,10 +79,13 @@ Trap::Trap()
       has_unsafe_traps_(false) {
   // Set new SIGSYS handler
   struct sigaction sa = {};
-  sa.sa_sigaction = SigSysAction;
-  sa.sa_flags = SA_SIGINFO | SA_NODEFER;
-  struct sigaction old_sa;
-  if (sigaction(SIGSYS, &sa, &old_sa) < 0) {
+  // In some toolchain, sa_sigaction is not declared in struct sigaction.
+  // So, here cast the pointer to the sa_handler's type. This works because
+  // |sa_handler| and |sa_sigaction| shares the same memory.
+  sa.sa_handler = reinterpret_cast<void (*)(int)>(SigSysAction);
+  sa.sa_flags = LINUX_SA_SIGINFO | LINUX_SA_NODEFER;
+  struct sigaction old_sa = {};
+  if (sys_sigaction(LINUX_SIGSYS, &sa, &old_sa) < 0) {
     SANDBOX_DIE("Failed to configure SIGSYS handler");
   }
 
@@ -99,8 +99,8 @@ Trap::Trap()
 
   // Unmask SIGSYS
   sigset_t mask;
-  if (sigemptyset(&mask) || sigaddset(&mask, SIGSYS) ||
-      sigprocmask(SIG_UNBLOCK, &mask, NULL)) {
+  if (sigemptyset(&mask) || sigaddset(&mask, LINUX_SIGSYS) ||
+      sys_sigprocmask(LINUX_SIG_UNBLOCK, &mask, NULL)) {
     SANDBOX_DIE("Failed to configure SIGSYS handler");
   }
 }
@@ -120,7 +120,7 @@ bpf_dsl::TrapRegistry* Trap::Registry() {
   return global_trap_;
 }
 
-void Trap::SigSysAction(int nr, siginfo_t* info, void* void_context) {
+void Trap::SigSysAction(int nr, LinuxSigInfo* info, void* void_context) {
   if (!global_trap_) {
     RAW_SANDBOX_DIE(
         "This can't happen. Found no global singleton instance "
@@ -129,7 +129,7 @@ void Trap::SigSysAction(int nr, siginfo_t* info, void* void_context) {
   global_trap_->SigSys(nr, info, void_context);
 }
 
-void Trap::SigSys(int nr, siginfo_t* info, void* void_context) {
+void Trap::SigSys(int nr, LinuxSigInfo* info, void* void_context) {
   // Signal handlers should always preserve "errno". Otherwise, we could
   // trigger really subtle bugs.
   const int old_errno = errno;
@@ -137,7 +137,7 @@ void Trap::SigSys(int nr, siginfo_t* info, void* void_context) {
   // Various sanity checks to make sure we actually received a signal
   // triggered by a BPF filter. If something else triggered SIGSYS
   // (e.g. kill()), there is really nothing we can do with this signal.
-  if (nr != SIGSYS || info->si_code != SYS_SECCOMP || !void_context ||
+  if (nr != LINUX_SIGSYS || info->si_code != SYS_SECCOMP || !void_context ||
       info->si_errno <= 0 ||
       static_cast<size_t>(info->si_errno) > trap_array_size_) {
     // ATI drivers seem to send SIGSYS, so this cannot be FATAL.