Linux sandbox: Allow restricting sched_* on other processes.

sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Note: any code in this file MUST be async-signal safe.
 
 #include "sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h"
 
+#include <sys/syscall.h>
 #include <unistd.h>
 
 #include "base/basictypes.h"
+#include "base/logging.h"
 #include "base/posix/eintr_wrapper.h"
 #include "build/build_config.h"
 #include "sandbox/linux/seccomp-bpf/sandbox_bpf.h"
+#include "sandbox/linux/seccomp-bpf/syscall.h"
+#include "sandbox/linux/services/linux_syscalls.h"
 
 #if defined(__mips__)
 // __NR_Linux, is defined in <asm/unistd.h>.
 #include <asm/unistd.h>
 #endif
 
 #define SECCOMP_MESSAGE_COMMON_CONTENT "seccomp-bpf failure"
 #define SECCOMP_MESSAGE_CLONE_CONTENT "clone() failure"
 #define SECCOMP_MESSAGE_PRCTL_CONTENT "prctl() failure"
 #define SECCOMP_MESSAGE_IOCTL_CONTENT "ioctl() failure"
@@ skipping 174 matching lines @@
   static const char kSeccompFutexError[] =
       __FILE__ ":**CRASHING**:" SECCOMP_MESSAGE_FUTEX_CONTENT "\n";
   WriteToStdErr(kSeccompFutexError, sizeof(kSeccompFutexError) - 1);
   volatile int futex_op = args.args[1];
   volatile char* addr = reinterpret_cast<volatile char*>(futex_op & 0xFFF);
   *addr = '\0';
   for (;;)
     _exit(1);
 }
 
+intptr_t SIGSYSSchedHandler(const struct arch_seccomp_data& args,
+                            void* aux) {
+  switch (args.nr) {
+    case __NR_sched_getaffinity:
+    case __NR_sched_getattr:
+    case __NR_sched_getparam:
+    case __NR_sched_getscheduler:
+    case __NR_sched_rr_get_interval:
+    case __NR_sched_setaffinity:
+    case __NR_sched_setattr:
+    case __NR_sched_setparam:
+    case __NR_sched_setscheduler:
+      const pid_t tid = syscall(__NR_gettid);
+      // The first argument is the pid.  If is our thread id, then replace it
+      // with 0, which is equivalent and allowed by the policy.
+      if (args.args[0] == static_cast<uint64_t>(tid)) {
+        return Syscall::Call(args.nr,
+                             0,
+                             static_cast<intptr_t>(args.args[1]),
+                             static_cast<intptr_t>(args.args[2]),
+                             static_cast<intptr_t>(args.args[3]),
+                             static_cast<intptr_t>(args.args[4]),
+                             static_cast<intptr_t>(args.args[5]));
+      }
+      break;
+  }
+
+  CrashSIGSYS_Handler(args, aux);
+
+  // Should never be reached.
+  RAW_CHECK(false);
+  return -ENOSYS;
+}
+
 bpf_dsl::ResultExpr CrashSIGSYS() {
   return bpf_dsl::Trap(CrashSIGSYS_Handler, NULL);
 }
 
 bpf_dsl::ResultExpr CrashSIGSYSClone() {
   return bpf_dsl::Trap(SIGSYSCloneFailure, NULL);
 }
 
 bpf_dsl::ResultExpr CrashSIGSYSPrctl() {
   return bpf_dsl::Trap(SIGSYSPrctlFailure, NULL);
 }
 
 bpf_dsl::ResultExpr CrashSIGSYSIoctl() {
   return bpf_dsl::Trap(SIGSYSIoctlFailure, NULL);
 }
 
 bpf_dsl::ResultExpr CrashSIGSYSKill() {
   return bpf_dsl::Trap(SIGSYSKillFailure, NULL);
 }
 
 bpf_dsl::ResultExpr CrashSIGSYSFutex() {
   return bpf_dsl::Trap(SIGSYSFutexFailure, NULL);
 }
 
+bpf_dsl::ResultExpr RewriteSchedSIGSYS() {
+  return bpf_dsl::Trap(SIGSYSSchedHandler, NULL);
+}
+
 const char* GetErrorMessageContentForTests() {
   return SECCOMP_MESSAGE_COMMON_CONTENT;
 }
 
 const char* GetCloneErrorMessageContentForTests() {
   return SECCOMP_MESSAGE_CLONE_CONTENT;
 }
 
 const char* GetPrctlErrorMessageContentForTests() {
   return SECCOMP_MESSAGE_PRCTL_CONTENT;
 }
 
 const char* GetIoctlErrorMessageContentForTests() {
   return SECCOMP_MESSAGE_IOCTL_CONTENT;
 }
 
 const char* GetKillErrorMessageContentForTests() {
   return SECCOMP_MESSAGE_KILL_CONTENT;
 }
 
 const char* GetFutexErrorMessageContentForTests() {
   return SECCOMP_MESSAGE_FUTEX_CONTENT;
 }
 
 }  // namespace sandbox.