Implement Merkle tree generate tool binary

This binary is used to recursively enable and generate Merkle tree files
for all files and directories in a file system from inside a gVisor
sandbox.

PiperOrigin-RevId: 362418770

1 files changed, 39 insertions, 0 deletions

diff --git a/tools/verity/measure_tool_unsafe.go b/tools/verity/measure_tool_unsafe.go
new file mode 100644
index 000000000..d4079be9e
--- /dev/null
+++ b/tools/verity/measure_tool_unsafe.go
@@ -0,0 +1,39 @@
+// Copyright 2021 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 main
+
+import (
+	"encoding/hex"
+	"fmt"
+	"os"
+	"syscall"
+	"unsafe"
+
+	"gvisor.dev/gvisor/pkg/abi/linux"
+)
+
+// measure prints the hash of path to stdout.
+func measure(path string) error {
+	f, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+	var digest digest
+	digest.metadata.DigestSize = maxDigestSize
+	if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, uintptr(f.Fd()), uintptr(linux.FS_IOC_MEASURE_VERITY), uintptr(unsafe.Pointer(&digest))); err != 0 {
+		return err
+	}
+	fmt.Fprintf(os.Stdout, "%s\n", hex.EncodeToString(digest.digest[:digest.metadata.DigestSize]))
+	return err
+}