1 files changed, 70 insertions, 0 deletions
diff --git a/pkg/seccomp/seccomp_unsafe.go b/pkg/seccomp/seccomp_unsafe.go
new file mode 100644
index 000000000..ebb6397e8
--- /dev/null
+++ b/pkg/seccomp/seccomp_unsafe.go
@@ -0,0 +1,70 @@
+// Copyright 2018 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package seccomp
+
+import (
+	"syscall"
+	"unsafe"
+
+	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
+)
+
+// sockFprog is sock_fprog taken from <linux/filter.h>.
+type sockFprog struct {
+	Len    uint16
+	pad    [6]byte
+	Filter *linux.BPFInstruction
+}
+
+// SetFilter installs the given BPF program.
+//
+// This is safe to call from an afterFork context.
+//
+//go:nosplit
+func SetFilter(instrs []linux.BPFInstruction) syscall.Errno {
+	// PR_SET_NO_NEW_PRIVS is required in order to enable seccomp. See seccomp(2) for details.
+	if _, _, errno := syscall.RawSyscall(syscall.SYS_PRCTL, linux.PR_SET_NO_NEW_PRIVS, 1, 0); errno != 0 {
+		return errno
+	}
+
+	sockProg := sockFprog{
+		Len:    uint16(len(instrs)),
+		Filter: (*linux.BPFInstruction)(unsafe.Pointer(&instrs[0])),
+	}
+	return seccomp(linux.SECCOMP_SET_MODE_FILTER, linux.SECCOMP_FILTER_FLAG_TSYNC, unsafe.Pointer(&sockProg))
+}
+
+func isKillProcessAvailable() (bool, error) {
+	action := uint32(linux.SECCOMP_RET_KILL_PROCESS)
+	if errno := seccomp(linux.SECCOMP_GET_ACTION_AVAIL, 0, unsafe.Pointer(&action)); errno != 0 {
+		// EINVAL: SECCOMP_GET_ACTION_AVAIL not in this kernel yet.
+		// EOPNOTSUPP: SECCOMP_RET_KILL_PROCESS not supported.
+		if errno == syscall.EINVAL || errno == syscall.EOPNOTSUPP {
+			return false, nil
+		}
+		return false, errno
+	}
+	return true, nil
+}
+
+// seccomp calls seccomp(2). This is safe to call from an afterFork context.
+//
+//go:nosplit
+func seccomp(op, flags uint32, ptr unsafe.Pointer) syscall.Errno {
+	if _, _, errno := syscall.RawSyscall(SYS_SECCOMP, uintptr(op), uintptr(flags), uintptr(ptr)); errno != 0 {
+		return errno
+	}
+	return 0
+}