Merge pull request #833 from theguy147/feat/qemu-qcow

feat: Add support for QEMU QCOW images

Author: devttys0

src/magic.rs

@@ -1152,6 +1152,17 @@ pub fn patterns() -> Vec<signatures::common::Signature> {
             description: signatures::dpapi::DESCRIPTION.to_string(),
             extractor: None,
         },
+        // QEMU QCOW image
+        signatures::common::Signature {
+            name: "qcow".to_string(),
+            short: true,
+            magic_offset: 0,
+            always_display: true,
+            magic: signatures::qcow::qcow_magic(),
+            parser: signatures::qcow::qcow_parser,
+            description: signatures::qcow::DESCRIPTION.to_string(),
+            extractor: None,
+      },
         // ARJ archive
         signatures::common::Signature {
             name: "arj".to_string(),

src/signatures.rs

@@ -172,6 +172,7 @@ pub mod pem;
 pub mod pjl;
 pub mod pkcs_der;
 pub mod png;
+pub mod qcow;
 pub mod qnx;
 pub mod rar;
 pub mod riff;

src/signatures/qcow.rs

@@ -0,0 +1,25 @@
+use crate::signatures::common::{SignatureError, SignatureResult, CONFIDENCE_MEDIUM};
+use crate::structures::qcow::parse_qcow_header;
+
+pub const DESCRIPTION: &str = "QEMU QCOW Image";
+
+pub fn qcow_magic() -> Vec<Vec<u8>> {
+    vec![b"QFI\xFB".to_vec()]
+}
+
+pub fn qcow_parser(file_data: &[u8], offset: usize) -> Result<SignatureResult, SignatureError> {
+    // Successful return value
+    let mut result = SignatureResult {
+        offset,
+        name: "qcow".to_string(),
+        confidence: CONFIDENCE_MEDIUM,
+        ..Default::default()
+    };
+
+    if let Ok(qcow_header) = parse_qcow_header(file_data) {
+        result.description = format!("QEMU QCOW Image, version: {}, storage media size: {:#x} bytes, cluster block size: {:#x} bytes, encryption method: {}", qcow_header.version, qcow_header.storage_media_size, 1 << qcow_header.cluster_block_bits, qcow_header.encryption_method);
+        return Ok(result);
+    };
+
+    Err(SignatureError)
+}

src/structures.rs

@@ -145,6 +145,7 @@ pub mod pcap;
 pub mod pchrom;
 pub mod pe;
 pub mod png;
+pub mod qcow;
 pub mod qnx;
 pub mod rar;
 pub mod riff;

src/structures/qcow.rs

@@ -0,0 +1,106 @@
+use crate::structures::common;
+use crate::structures::common::StructureError;
+use std::collections::HashMap;
+
+#[derive(Debug, Default, Clone)]
+pub struct QcowHeader {
+    pub version: u8,
+    pub storage_media_size: u64,
+    pub cluster_block_bits: u8,
+    pub encryption_method: String,
+}
+
+pub fn parse_qcow_header(qcow_data: &[u8]) -> Result<QcowHeader, StructureError> {
+    let qcow_basehdr_structure = vec![("magic", "u32"), ("version", "u32")];
+    let qcow_header_v1_structure = vec![
+        ("backing_filename_offset", "u64"),
+        ("backing_filename_size", "u32"),
+        ("modification_timestamp", "u32"),
+        ("storage_media_size", "u64"),
+        ("cluster_block_bits", "u8"),
+        ("level2_table_bits", "u8"),
+        ("reserved1", "u16"),
+        ("encryption_method", "u32"),
+        ("level1_table_offset", "u64"),
+    ];
+    let qcow_header_v2_structure = vec![
+        ("backing_filename_offset", "u64"),
+        ("backing_filename_size", "u32"),
+        ("cluster_block_bits", "u32"),
+        ("storage_media_size", "u64"),
+        ("encryption_method", "u32"),
+        ("level1_table_refs", "u32"),
+        ("level1_table_offset", "u64"),
+        ("refcount_table_offset", "u64"),
+        ("refcount_table_clusters", "u32"),
+        ("snapshot_count", "u32"),
+        ("snapshot_offset", "u64"),
+    ];
+    let qcow_header_v3_structure = vec![
+        ("backing_filename_offset", "u64"),
+        ("backing_filename_size", "u32"),
+        ("cluster_block_bits", "u32"),
+        ("storage_media_size", "u64"),
+        ("encryption_method", "u32"),
+        ("level1_table_refs", "u32"),
+        ("level1_table_offset", "u64"),
+        ("refcount_table_offset", "u64"),
+        ("refcount_table_clusters", "u32"),
+        ("snapshot_count", "u32"),
+        ("snapshot_offset", "u64"),
+        ("incompatible_feature_flags", "u64"),
+        ("compatible_feature_flags", "u64"),
+        ("autoclear_feature_flags", "u64"),
+        ("refcount_order", "u32"),
+        ("file_hdr_size", "u32"), // 104 or 112
+    ];
+
+    let encryption_methods = HashMap::from([(0, "None"), (1, "AES128-CBC"), (2, "LUKS")]);
+
+    if let Ok(qcow_base_header) = common::parse(qcow_data, &qcow_basehdr_structure, "big") {
+        let qcow_version = qcow_base_header["version"];
+        let qcow_data = qcow_data.get(8..).ok_or(StructureError)?;
+        let qcow_header = match qcow_version {
+            1 => common::parse(qcow_data, &qcow_header_v1_structure, "big"),
+            2 => common::parse(qcow_data, &qcow_header_v2_structure, "big"),
+            3 => common::parse(qcow_data, &qcow_header_v3_structure, "big"),
+            _ => Err(StructureError),
+        }?;
+
+        let encryption_method = encryption_methods
+            .get(&qcow_header["encryption_method"])
+            .ok_or(StructureError)?
+            .to_string();
+
+        let cluster_block_bits = *qcow_header
+            .get("cluster_block_bits")
+            .filter(|&&bits| (9..=21).contains(&bits))
+            .ok_or(StructureError)?;
+
+        // sanity check: existing offsets need to be aligned to cluster boundary
+        if let Some(offset) = qcow_header.get("level1_table_offset") {
+            if offset % (1 << cluster_block_bits) != 0 {
+                return Err(StructureError);
+            }
+        }
+        if let Some(offset) = qcow_header.get("refcount_table_offset") {
+            if offset % (1 << cluster_block_bits) != 0 {
+                return Err(StructureError);
+            }
+        }
+        if let Some(offset) = qcow_header.get("snapshot_offset") {
+            if offset % (1 << cluster_block_bits) != 0 {
+                return Err(StructureError);
+            }
+        }
+
+        return Ok(QcowHeader {
+            version: qcow_version as u8,
+            storage_media_size: qcow_header["storage_media_size"] as u64,
+            cluster_block_bits: cluster_block_bits as u8,
+            encryption_method,
+        });
+    }
+
+    Err(StructureError)
+}

tests/inputs/qcow.bin

@@ -0,0 +1,17 @@
+mod common;
+
+#[test]
+fn integration_test() {
+    const SIGNATURE_TYPE: &str = "qcow";
+    const INPUT_FILE_NAME: &str = "qcow.bin";
+
+    let expected_signature_offsets: Vec<usize> = vec![0];
+    let expected_extraction_offsets: Vec<usize> = vec![];
+
+    let results = common::run_binwalk(SIGNATURE_TYPE, INPUT_FILE_NAME);
+    common::assert_results_ok(
+        results,
+        expected_signature_offsets,
+        expected_extraction_offsets,
+    );
+}