Consolidate fs-verity wrapper in libfsverity_rs
Bug: 272587415
Test: m libfsverity_rs
Change-Id: I9370d4cf66b34b6b86fda60f22ea096ce038da07
diff --git a/fsverity/libfsverity_rs/Android.bp b/fsverity/libfsverity_rs/Android.bp
new file mode 100644
index 0000000..91b1248
--- /dev/null
+++ b/fsverity/libfsverity_rs/Android.bp
@@ -0,0 +1,17 @@
+package {
+ default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+rust_library {
+ name: "libfsverity_rs",
+ crate_name: "fsverity",
+ srcs: ["lib.rs"],
+ edition: "2021",
+ rustlibs: [
+ "libnix",
+ ],
+ apex_available: [
+ "com.android.compos",
+ "com.android.virt",
+ ],
+}
diff --git a/fsverity/libfsverity_rs/lib.rs b/fsverity/libfsverity_rs/lib.rs
new file mode 100644
index 0000000..473b2d5
--- /dev/null
+++ b/fsverity/libfsverity_rs/lib.rs
@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * 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.
+ */
+
+//! A wrapper library to use fs-verity
+
+mod sys;
+
+use crate::sys::*;
+use std::io;
+use std::os::fd::AsRawFd;
+use std::os::unix::io::BorrowedFd;
+
+fn read_metadata(fd: i32, metadata_type: u64, offset: u64, buf: &mut [u8]) -> io::Result<usize> {
+ let mut arg = fsverity_read_metadata_arg {
+ metadata_type,
+ offset,
+ length: buf.len() as u64,
+ buf_ptr: buf.as_mut_ptr() as u64,
+ __reserved: 0,
+ };
+ // SAFETY: the ioctl doesn't change the sematics in the current process
+ Ok(unsafe { read_verity_metadata(fd, &mut arg) }? as usize)
+}
+
+/// Read the raw Merkle tree from the fd, if it exists. The API semantics is similar to a regular
+/// pread(2), and may not return full requested buffer.
+pub fn read_merkle_tree(fd: i32, offset: u64, buf: &mut [u8]) -> io::Result<usize> {
+ read_metadata(fd, FS_VERITY_METADATA_TYPE_MERKLE_TREE, offset, buf)
+}
+
+/// Read the fs-verity signature from the fd (if exists). The returned signature should be complete.
+pub fn read_signature(fd: i32, buf: &mut [u8]) -> io::Result<usize> {
+ read_metadata(fd, FS_VERITY_METADATA_TYPE_SIGNATURE, 0 /* offset */, buf)
+}
+
+/// Enable fs-verity to the `fd`, with sha256 hash algorithm and 4KB block size.
+pub fn enable(fd: BorrowedFd) -> io::Result<()> {
+ let arg = fsverity_enable_arg {
+ version: 1,
+ hash_algorithm: FS_VERITY_HASH_ALG_SHA256,
+ block_size: 4096,
+ salt_size: 0,
+ salt_ptr: 0,
+ sig_size: 0,
+ __reserved1: 0,
+ sig_ptr: 0,
+ __reserved2: [0; 11],
+ };
+ // SAFETY: the ioctl doesn't change the sematics in the current process
+ if unsafe { enable_verity(fd.as_raw_fd(), &arg) } == Ok(0) {
+ Ok(())
+ } else {
+ Err(io::Error::last_os_error())
+ }
+}
diff --git a/fsverity/libfsverity_rs/sys.rs b/fsverity/libfsverity_rs/sys.rs
new file mode 100644
index 0000000..8ce0836
--- /dev/null
+++ b/fsverity/libfsverity_rs/sys.rs
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * 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.
+ */
+
+//! Stable API definition copied from uapi/linux/fsverity.h
+
+use nix::{ioctl_readwrite, ioctl_write_ptr};
+
+const FS_IOCTL_MAGIC: u8 = b'f';
+const FS_IOC_ENABLE_VERITY: u8 = 133;
+const FS_IOCTL_READ_VERITY_METADATA: u8 = 135;
+
+pub const FS_VERITY_HASH_ALG_SHA256: u32 = 1;
+pub const FS_VERITY_METADATA_TYPE_MERKLE_TREE: u64 = 1;
+pub const FS_VERITY_METADATA_TYPE_SIGNATURE: u64 = 3;
+
+#[repr(C)]
+pub struct fsverity_read_metadata_arg {
+ pub metadata_type: u64,
+ pub offset: u64,
+ pub length: u64,
+ pub buf_ptr: u64,
+ pub __reserved: u64,
+}
+
+ioctl_readwrite!(
+ read_verity_metadata,
+ FS_IOCTL_MAGIC,
+ FS_IOCTL_READ_VERITY_METADATA,
+ fsverity_read_metadata_arg
+);
+
+#[repr(C)]
+pub struct fsverity_enable_arg {
+ pub version: u32,
+ pub hash_algorithm: u32,
+ pub block_size: u32,
+ pub salt_size: u32,
+ pub salt_ptr: u64,
+ pub sig_size: u32,
+ pub __reserved1: u32,
+ pub sig_ptr: u64,
+ pub __reserved2: [u64; 11],
+}
+
+ioctl_write_ptr!(enable_verity, FS_IOCTL_MAGIC, FS_IOC_ENABLE_VERITY, fsverity_enable_arg);