Linux sandbox: restrict *kill to the current process.

sandbox/linux/seccomp-bpf-helpers/syscall_parameters_restrictions.h

 // 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.
 
 #ifndef SANDBOX_LINUX_SECCOMP_BPF_HELPERS_SYSCALL_PARAMETERS_RESTRICTIONS_H_
 #define SANDBOX_LINUX_SECCOMP_BPF_HELPERS_SYSCALL_PARAMETERS_RESTRICTIONS_H_
 
+#include <unistd.h>
+
 #include "build/build_config.h"
 #include "sandbox/linux/sandbox_export.h"
 
 // These are helpers to build seccomp-bpf policies, i.e. policies for a
 // sandbox that reduces the Linux kernel's attack surface. They return an
 // SANDBOX_EXPORT ErrorCode suitable to restrict certain system call parameters.
 
 namespace sandbox {
 
 class ErrorCode;
@@ skipping 30 matching lines @@
 // Also, in F_SETFL, restrict the allowed flags to: O_ACCMODE | O_APPEND |
 // O_NONBLOCK | O_SYNC | O_LARGEFILE | O_CLOEXEC | O_NOATIME.
 SANDBOX_EXPORT ErrorCode RestrictFcntlCommands(SandboxBPF* sandbox);
 
 #if defined(__i386__)
 // Restrict socketcall(2) to only allow socketpair(2), send(2), recv(2),
 // sendto(2), recvfrom(2), shutdown(2), sendmsg(2) and recvmsg(2).
 SANDBOX_EXPORT ErrorCode RestrictSocketcallCommand(SandboxBPF* sandbox);
 #endif
 
+// Restrict |sysno| (which must be kill, tkill or tgkill) by allowing tgkill or
+// kill iff the first parameter is |target_pid|, crashing otherwise or if
+// |sysno| is tkill.
+ErrorCode RestrictKillTarget(pid_t target_pid, SandboxBPF* sandbox, int sysno);
+
 }  // namespace sandbox.
 
 #endif  // SANDBOX_LINUX_SECCOMP_BPF_HELPERS_SYSCALL_PARAMETERS_RESTRICTIONS_H_