7 files changed, 1130 insertions, 0 deletions

diff --git a/otautil/Android.bp b/otautil/Android.bp
index 557b8a313..4b043adf1 100644
--- a/otautil/Android.bp
+++ b/otautil/Android.bp
@@ -34,16 +34,21 @@ cc_library_static {
 
     // Minimal set of files to support host build.
     srcs: [
+        "asn1_decoder.cpp",
         "dirutil.cpp",
+        "package.cpp",
         "paths.cpp",
         "rangeset.cpp",
         "sysutil.cpp",
+        "verifier.cpp",
     ],
 
     shared_libs: [
         "libbase",
+        "libcrypto",
         "libcutils",
         "libselinux",
+        "libziparchive",
     ],
 
     export_include_dirs: [
diff --git a/otautil/asn1_decoder.cpp b/otautil/asn1_decoder.cpp
new file mode 100644
index 000000000..2d81a6e13
--- /dev/null
+++ b/otautil/asn1_decoder.cpp
@@ -0,0 +1,156 @@
+/*
+ * Copyright (C) 2013 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.
+ */
+
+#include "private/asn1_decoder.h"
+
+int asn1_context::peek_byte() const {
+  if (length_ == 0) {
+    return -1;
+  }
+  return *p_;
+}
+
+int asn1_context::get_byte() {
+  if (length_ == 0) {
+    return -1;
+  }
+
+  int byte = *p_;
+  p_++;
+  length_--;
+  return byte;
+}
+
+bool asn1_context::skip_bytes(size_t num_skip) {
+  if (length_ < num_skip) {
+    return false;
+  }
+  p_ += num_skip;
+  length_ -= num_skip;
+  return true;
+}
+
+bool asn1_context::decode_length(size_t* out_len) {
+  int num_octets = get_byte();
+  if (num_octets == -1) {
+    return false;
+  }
+  if ((num_octets & 0x80) == 0x00) {
+    *out_len = num_octets;
+    return true;
+  }
+  num_octets &= kMaskTag;
+  if (static_cast<size_t>(num_octets) >= sizeof(size_t)) {
+    return false;
+  }
+  size_t length = 0;
+  for (int i = 0; i < num_octets; ++i) {
+    int byte = get_byte();
+    if (byte == -1) {
+      return false;
+    }
+    length <<= 8;
+    length += byte;
+  }
+  *out_len = length;
+  return true;
+}
+
+/**
+ * Returns the constructed type and advances the pointer. E.g. A0 -> 0
+ */
+asn1_context* asn1_context::asn1_constructed_get() {
+  int type = get_byte();
+  if (type == -1 || (type & kMaskConstructed) != kTagConstructed) {
+    return nullptr;
+  }
+  size_t length;
+  if (!decode_length(&length) || length > length_) {
+    return nullptr;
+  }
+  asn1_context* app_ctx = new asn1_context(p_, length);
+  app_ctx->app_type_ = type & kMaskAppType;
+  return app_ctx;
+}
+
+bool asn1_context::asn1_constructed_skip_all() {
+  int byte = peek_byte();
+  while (byte != -1 && (byte & kMaskConstructed) == kTagConstructed) {
+    skip_bytes(1);
+    size_t length;
+    if (!decode_length(&length) || !skip_bytes(length)) {
+      return false;
+    }
+    byte = peek_byte();
+  }
+  return byte != -1;
+}
+
+int asn1_context::asn1_constructed_type() const {
+  return app_type_;
+}
+
+asn1_context* asn1_context::asn1_sequence_get() {
+  if ((get_byte() & kMaskTag) != kTagSequence) {
+    return nullptr;
+  }
+  size_t length;
+  if (!decode_length(&length) || length > length_) {
+    return nullptr;
+  }
+  return new asn1_context(p_, length);
+}
+
+asn1_context* asn1_context::asn1_set_get() {
+  if ((get_byte() & kMaskTag) != kTagSet) {
+    return nullptr;
+  }
+  size_t length;
+  if (!decode_length(&length) || length > length_) {
+    return nullptr;
+  }
+  return new asn1_context(p_, length);
+}
+
+bool asn1_context::asn1_sequence_next() {
+  size_t length;
+  if (get_byte() == -1 || !decode_length(&length) || !skip_bytes(length)) {
+    return false;
+  }
+  return true;
+}
+
+bool asn1_context::asn1_oid_get(const uint8_t** oid, size_t* length) {
+  if (get_byte() != kTagOid) {
+    return false;
+  }
+  if (!decode_length(length) || *length == 0 || *length > length_) {
+    return false;
+  }
+  *oid = p_;
+  return true;
+}
+
+bool asn1_context::asn1_octet_string_get(const uint8_t** octet_string, size_t* length) {
+  if (get_byte() != kTagOctetString) {
+    return false;
+  }
+  if (!decode_length(length) || *length == 0 || *length > length_) {
+    return false;
+  }
+  *octet_string = p_;
+  return true;
+}
diff --git a/otautil/include/otautil/package.h b/otautil/include/otautil/package.h
new file mode 100644
index 000000000..f4f4d348b
--- /dev/null
+++ b/otautil/include/otautil/package.h
@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+#include <functional>
+#include <map>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include <ziparchive/zip_archive.h>
+
+#include "otautil/verifier.h"
+
+enum class PackageType {
+  kMemory,
+  kFile,
+};
+
+// This class serves as a wrapper for an OTA update package. It aims to provide the common
+// interface for both packages loaded in memory and packages read from fd.
+class Package : public VerifierInterface {
+ public:
+  static std::unique_ptr<Package> CreateMemoryPackage(
+      const std::string& path, const std::function<void(float)>& set_progress);
+  static std::unique_ptr<Package> CreateMemoryPackage(
+      std::vector<uint8_t> content, const std::function<void(float)>& set_progress);
+  static std::unique_ptr<Package> CreateFilePackage(const std::string& path,
+                                                    const std::function<void(float)>& set_progress);
+
+  virtual ~Package() = default;
+
+  virtual PackageType GetType() const = 0;
+
+  virtual std::string GetPath() const = 0;
+
+  // Opens the package as a zip file and returns the ZipArchiveHandle.
+  virtual ZipArchiveHandle GetZipArchiveHandle() = 0;
+
+  // Updates the progress in fraction during package verification.
+  void SetProgress(float progress) override;
+
+ protected:
+  // An optional function to update the progress.
+  std::function<void(float)> set_progress_;
+};
diff --git a/otautil/include/otautil/verifier.h b/otautil/include/otautil/verifier.h
new file mode 100644
index 000000000..f9e947580
--- /dev/null
+++ b/otautil/include/otautil/verifier.h
@@ -0,0 +1,101 @@
+/*
+ * Copyright (C) 2008 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.
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+#include <functional>
+#include <memory>
+#include <vector>
+
+#include <openssl/ec_key.h>
+#include <openssl/rsa.h>
+#include <openssl/sha.h>
+
+constexpr size_t MiB = 1024 * 1024;
+
+using HasherUpdateCallback = std::function<void(const uint8_t* addr, uint64_t size)>;
+
+struct RSADeleter {
+  void operator()(RSA* rsa) const {
+    RSA_free(rsa);
+  }
+};
+
+struct ECKEYDeleter {
+  void operator()(EC_KEY* ec_key) const {
+    EC_KEY_free(ec_key);
+  }
+};
+
+struct Certificate {
+  typedef enum {
+    KEY_TYPE_RSA,
+    KEY_TYPE_EC,
+  } KeyType;
+
+  Certificate(int hash_len_, KeyType key_type_, std::unique_ptr<RSA, RSADeleter>&& rsa_,
+              std::unique_ptr<EC_KEY, ECKEYDeleter>&& ec_)
+      : hash_len(hash_len_), key_type(key_type_), rsa(std::move(rsa_)), ec(std::move(ec_)) {}
+
+  // SHA_DIGEST_LENGTH (SHA-1) or SHA256_DIGEST_LENGTH (SHA-256)
+  int hash_len;
+  KeyType key_type;
+  std::unique_ptr<RSA, RSADeleter> rsa;
+  std::unique_ptr<EC_KEY, ECKEYDeleter> ec;
+};
+
+class VerifierInterface {
+ public:
+  virtual ~VerifierInterface() = default;
+
+  // Returns the package size in bytes.
+  virtual uint64_t GetPackageSize() const = 0;
+
+  // Reads |byte_count| data starting from |offset|, and puts the result in |buffer|.
+  virtual bool ReadFullyAtOffset(uint8_t* buffer, uint64_t byte_count, uint64_t offset) = 0;
+
+  // Updates the hash contexts for |length| bytes data starting from |start|.
+  virtual bool UpdateHashAtOffset(const std::vector<HasherUpdateCallback>& hashers, uint64_t start,
+                                  uint64_t length) = 0;
+
+  // Updates the progress in fraction during package verification.
+  virtual void SetProgress(float progress) = 0;
+};
+
+//  Looks for an RSA signature embedded in the .ZIP file comment given the path to the zip.
+//  Verifies that it matches one of the given public keys. Returns VERIFY_SUCCESS or
+//  VERIFY_FAILURE (if any error is encountered or no key matches the signature).
+int verify_file(VerifierInterface* package, const std::vector<Certificate>& keys);
+
+// Checks that the RSA key has a modulus of 2048 or 4096 bits long, and public exponent is 3 or
+// 65537.
+bool CheckRSAKey(const std::unique_ptr<RSA, RSADeleter>& rsa);
+
+// Checks that the field size of the curve for the EC key is 256 bits.
+bool CheckECKey(const std::unique_ptr<EC_KEY, ECKEYDeleter>& ec_key);
+
+// Parses a PEM-encoded x509 certificate from the given buffer and saves it into |cert|. Returns
+// false if there is a parsing failure or the signature's encryption algorithm is not supported.
+bool LoadCertificateFromBuffer(const std::vector<uint8_t>& pem_content, Certificate* cert);
+
+// Iterates over the zip entries with the suffix "x509.pem" and returns a list of recognized
+// certificates. Returns an empty list if we fail to parse any of the entries.
+std::vector<Certificate> LoadKeysFromZipfile(const std::string& zip_name);
+
+#define VERIFY_SUCCESS 0
+#define VERIFY_FAILURE 1
diff --git a/otautil/include/private/asn1_decoder.h b/otautil/include/private/asn1_decoder.h
new file mode 100644
index 000000000..e5337d9c4
--- /dev/null
+++ b/otautil/include/private/asn1_decoder.h
@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2013 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.
+ */
+
+#ifndef ASN1_DECODER_H_
+#define ASN1_DECODER_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+class asn1_context {
+ public:
+  asn1_context(const uint8_t* buffer, size_t length) : p_(buffer), length_(length), app_type_(0) {}
+  int asn1_constructed_type() const;
+  asn1_context* asn1_constructed_get();
+  bool asn1_constructed_skip_all();
+  asn1_context* asn1_sequence_get();
+  asn1_context* asn1_set_get();
+  bool asn1_sequence_next();
+  bool asn1_oid_get(const uint8_t** oid, size_t* length);
+  bool asn1_octet_string_get(const uint8_t** octet_string, size_t* length);
+
+ private:
+  static constexpr int kMaskConstructed = 0xE0;
+  static constexpr int kMaskTag = 0x7F;
+  static constexpr int kMaskAppType = 0x1F;
+
+  static constexpr int kTagOctetString = 0x04;
+  static constexpr int kTagOid = 0x06;
+  static constexpr int kTagSequence = 0x30;
+  static constexpr int kTagSet = 0x31;
+  static constexpr int kTagConstructed = 0xA0;
+
+  int peek_byte() const;
+  int get_byte();
+  bool skip_bytes(size_t num_skip);
+  bool decode_length(size_t* out_len);
+
+  const uint8_t* p_;
+  size_t length_;
+  int app_type_;
+};
+
+#endif /* ASN1_DECODER_H_ */
diff --git a/otautil/package.cpp b/otautil/package.cpp
new file mode 100644
index 000000000..242204ee6
--- /dev/null
+++ b/otautil/package.cpp
@@ -0,0 +1,278 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+#include "otautil/package.h"
+
+#include <string.h>
+#include <unistd.h>
+
+#include <android-base/file.h>
+#include <android-base/logging.h>
+#include <android-base/stringprintf.h>
+#include <android-base/unique_fd.h>
+
+#include "otautil/error_code.h"
+#include "otautil/sysutil.h"
+
+// This class wraps the package in memory, i.e. a memory mapped package, or a package loaded
+// to a string/vector.
+class MemoryPackage : public Package {
+ public:
+  // Constructs the class from a file. We will memory maps the file later.
+  MemoryPackage(const std::string& path, std::unique_ptr<MemMapping> map,
+                const std::function<void(float)>& set_progress);
+
+  // Constructs the class from the package bytes in |content|.
+  MemoryPackage(std::vector<uint8_t> content, const std::function<void(float)>& set_progress);
+
+  ~MemoryPackage() override;
+
+  PackageType GetType() const override {
+    return PackageType::kMemory;
+  }
+
+  // Memory maps the package file if necessary. Initializes the start address and size of the
+  // package.
+  uint64_t GetPackageSize() const override {
+    return package_size_;
+  }
+
+  std::string GetPath() const override {
+    return path_;
+  }
+
+  bool ReadFullyAtOffset(uint8_t* buffer, uint64_t byte_count, uint64_t offset) override;
+
+  ZipArchiveHandle GetZipArchiveHandle() override;
+
+  bool UpdateHashAtOffset(const std::vector<HasherUpdateCallback>& hashers, uint64_t start,
+                          uint64_t length) override;
+
+ private:
+  const uint8_t* addr_;    // Start address of the package in memory.
+  uint64_t package_size_;  // Package size in bytes.
+
+  // The memory mapped package.
+  std::unique_ptr<MemMapping> map_;
+  // A copy of the package content, valid only if we create the class with the exact bytes of
+  // the package.
+  std::vector<uint8_t> package_content_;
+  // The physical path to the package, empty if we create the class with the package content.
+  std::string path_;
+
+  // The ZipArchiveHandle of the package.
+  ZipArchiveHandle zip_handle_;
+};
+
+void Package::SetProgress(float progress) {
+  if (set_progress_) {
+    set_progress_(progress);
+  }
+}
+
+class FilePackage : public Package {
+ public:
+  FilePackage(android::base::unique_fd&& fd, uint64_t file_size, const std::string& path,
+              const std::function<void(float)>& set_progress);
+
+  ~FilePackage() override;
+
+  PackageType GetType() const override {
+    return PackageType::kFile;
+  }
+
+  uint64_t GetPackageSize() const override {
+    return package_size_;
+  }
+
+  std::string GetPath() const override {
+    return path_;
+  }
+
+  bool ReadFullyAtOffset(uint8_t* buffer, uint64_t byte_count, uint64_t offset) override;
+
+  ZipArchiveHandle GetZipArchiveHandle() override;
+
+  bool UpdateHashAtOffset(const std::vector<HasherUpdateCallback>& hashers, uint64_t start,
+                          uint64_t length) override;
+
+ private:
+  android::base::unique_fd fd_;  // The underlying fd to the open package.
+  uint64_t package_size_;
+  std::string path_;  // The physical path to the package.
+
+  ZipArchiveHandle zip_handle_;
+};
+
+std::unique_ptr<Package> Package::CreateMemoryPackage(
+    const std::string& path, const std::function<void(float)>& set_progress) {
+  std::unique_ptr<MemMapping> mmap = std::make_unique<MemMapping>();
+  if (!mmap->MapFile(path)) {
+    LOG(ERROR) << "failed to map file";
+    return nullptr;
+  }
+
+  return std::make_unique<MemoryPackage>(path, std::move(mmap), set_progress);
+}
+
+std::unique_ptr<Package> Package::CreateFilePackage(
+    const std::string& path, const std::function<void(float)>& set_progress) {
+  android::base::unique_fd fd(open(path.c_str(), O_RDONLY));
+  if (fd == -1) {
+    PLOG(ERROR) << "Failed to open " << path;
+    return nullptr;
+  }
+
+  off64_t file_size = lseek64(fd.get(), 0, SEEK_END);
+  if (file_size == -1) {
+    PLOG(ERROR) << "Failed to get the package size";
+    return nullptr;
+  }
+
+  return std::make_unique<FilePackage>(std::move(fd), file_size, path, set_progress);
+}
+
+std::unique_ptr<Package> Package::CreateMemoryPackage(
+    std::vector<uint8_t> content, const std::function<void(float)>& set_progress) {
+  return std::make_unique<MemoryPackage>(std::move(content), set_progress);
+}
+
+MemoryPackage::MemoryPackage(const std::string& path, std::unique_ptr<MemMapping> map,
+                             const std::function<void(float)>& set_progress)
+    : map_(std::move(map)), path_(path), zip_handle_(nullptr) {
+  addr_ = map_->addr;
+  package_size_ = map_->length;
+  set_progress_ = set_progress;
+}
+
+MemoryPackage::MemoryPackage(std::vector<uint8_t> content,
+                             const std::function<void(float)>& set_progress)
+    : package_content_(std::move(content)), zip_handle_(nullptr) {
+  CHECK(!package_content_.empty());
+  addr_ = package_content_.data();
+  package_size_ = package_content_.size();
+  set_progress_ = set_progress;
+}
+
+MemoryPackage::~MemoryPackage() {
+  if (zip_handle_) {
+    CloseArchive(zip_handle_);
+  }
+}
+
+bool MemoryPackage::ReadFullyAtOffset(uint8_t* buffer, uint64_t byte_count, uint64_t offset) {
+  if (byte_count > package_size_ || offset > package_size_ - byte_count) {
+    LOG(ERROR) << "Out of bound read, offset: " << offset << ", size: " << byte_count
+               << ", total package_size: " << package_size_;
+    return false;
+  }
+  memcpy(buffer, addr_ + offset, byte_count);
+  return true;
+}
+
+bool MemoryPackage::UpdateHashAtOffset(const std::vector<HasherUpdateCallback>& hashers,
+                                       uint64_t start, uint64_t length) {
+  if (length > package_size_ || start > package_size_ - length) {
+    LOG(ERROR) << "Out of bound read, offset: " << start << ", size: " << length
+               << ", total package_size: " << package_size_;
+    return false;
+  }
+
+  for (const auto& hasher : hashers) {
+    hasher(addr_ + start, length);
+  }
+  return true;
+}
+
+ZipArchiveHandle MemoryPackage::GetZipArchiveHandle() {
+  if (zip_handle_) {
+    return zip_handle_;
+  }
+
+  if (auto err = OpenArchiveFromMemory(const_cast<uint8_t*>(addr_), package_size_, path_.c_str(),
+                                       &zip_handle_);
+      err != 0) {
+    LOG(ERROR) << "Can't open package" << path_ << " : " << ErrorCodeString(err);
+    return nullptr;
+  }
+
+  return zip_handle_;
+}
+
+FilePackage::FilePackage(android::base::unique_fd&& fd, uint64_t file_size, const std::string& path,
+                         const std::function<void(float)>& set_progress)
+    : fd_(std::move(fd)), package_size_(file_size), path_(path), zip_handle_(nullptr) {
+  set_progress_ = set_progress;
+}
+
+FilePackage::~FilePackage() {
+  if (zip_handle_) {
+    CloseArchive(zip_handle_);
+  }
+}
+
+bool FilePackage::ReadFullyAtOffset(uint8_t* buffer, uint64_t byte_count, uint64_t offset) {
+  if (byte_count > package_size_ || offset > package_size_ - byte_count) {
+    LOG(ERROR) << "Out of bound read, offset: " << offset << ", size: " << byte_count
+               << ", total package_size: " << package_size_;
+    return false;
+  }
+
+  if (!android::base::ReadFullyAtOffset(fd_.get(), buffer, byte_count, offset)) {
+    PLOG(ERROR) << "Failed to read " << byte_count << " bytes data at offset " << offset;
+    return false;
+  }
+
+  return true;
+}
+
+bool FilePackage::UpdateHashAtOffset(const std::vector<HasherUpdateCallback>& hashers,
+                                     uint64_t start, uint64_t length) {
+  if (length > package_size_ || start > package_size_ - length) {
+    LOG(ERROR) << "Out of bound read, offset: " << start << ", size: " << length
+               << ", total package_size: " << package_size_;
+    return false;
+  }
+
+  uint64_t so_far = 0;
+  while (so_far < length) {
+    uint64_t read_size = std::min<uint64_t>(length - so_far, 16 * MiB);
+    std::vector<uint8_t> buffer(read_size);
+    if (!ReadFullyAtOffset(buffer.data(), read_size, start + so_far)) {
+      return false;
+    }
+
+    for (const auto& hasher : hashers) {
+      hasher(buffer.data(), read_size);
+    }
+    so_far += read_size;
+  }
+
+  return true;
+}
+
+ZipArchiveHandle FilePackage::GetZipArchiveHandle() {
+  if (zip_handle_) {
+    return zip_handle_;
+  }
+
+  if (auto err = OpenArchiveFd(fd_.get(), path_.c_str(), &zip_handle_, false); err != 0) {
+    LOG(ERROR) << "Can't open package" << path_ << " : " << ErrorCodeString(err);
+    return nullptr;
+  }
+
+  return zip_handle_;
+}
diff --git a/otautil/verifier.cpp b/otautil/verifier.cpp
new file mode 100644
index 000000000..92b9faf29
--- /dev/null
+++ b/otautil/verifier.cpp
@@ -0,0 +1,472 @@
+/*
+ * Copyright (C) 2008 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.
+ */
+
+#include "otautil/verifier.h"
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <algorithm>
+#include <functional>
+#include <memory>
+#include <vector>
+
+#include <android-base/logging.h>
+#include <openssl/bio.h>
+#include <openssl/bn.h>
+#include <openssl/ecdsa.h>
+#include <openssl/evp.h>
+#include <openssl/obj_mac.h>
+#include <openssl/pem.h>
+#include <openssl/rsa.h>
+#include <ziparchive/zip_archive.h>
+
+#include "otautil/print_sha1.h"
+#include "private/asn1_decoder.h"
+
+/*
+ * Simple version of PKCS#7 SignedData extraction. This extracts the
+ * signature OCTET STRING to be used for signature verification.
+ *
+ * For full details, see http://www.ietf.org/rfc/rfc3852.txt
+ *
+ * The PKCS#7 structure looks like:
+ *
+ *   SEQUENCE (ContentInfo)
+ *     OID (ContentType)
+ *     [0] (content)
+ *       SEQUENCE (SignedData)
+ *         INTEGER (version CMSVersion)
+ *         SET (DigestAlgorithmIdentifiers)
+ *         SEQUENCE (EncapsulatedContentInfo)
+ *         [0] (CertificateSet OPTIONAL)
+ *         [1] (RevocationInfoChoices OPTIONAL)
+ *         SET (SignerInfos)
+ *           SEQUENCE (SignerInfo)
+ *             INTEGER (CMSVersion)
+ *             SEQUENCE (SignerIdentifier)
+ *             SEQUENCE (DigestAlgorithmIdentifier)
+ *             SEQUENCE (SignatureAlgorithmIdentifier)
+ *             OCTET STRING (SignatureValue)
+ */
+static bool read_pkcs7(const uint8_t* pkcs7_der, size_t pkcs7_der_len,
+                       std::vector<uint8_t>* sig_der) {
+  CHECK(sig_der != nullptr);
+  sig_der->clear();
+
+  asn1_context ctx(pkcs7_der, pkcs7_der_len);
+
+  std::unique_ptr<asn1_context> pkcs7_seq(ctx.asn1_sequence_get());
+  if (pkcs7_seq == nullptr || !pkcs7_seq->asn1_sequence_next()) {
+    return false;
+  }
+
+  std::unique_ptr<asn1_context> signed_data_app(pkcs7_seq->asn1_constructed_get());
+  if (signed_data_app == nullptr) {
+    return false;
+  }
+
+  std::unique_ptr<asn1_context> signed_data_seq(signed_data_app->asn1_sequence_get());
+  if (signed_data_seq == nullptr || !signed_data_seq->asn1_sequence_next() ||
+      !signed_data_seq->asn1_sequence_next() || !signed_data_seq->asn1_sequence_next() ||
+      !signed_data_seq->asn1_constructed_skip_all()) {
+    return false;
+  }
+
+  std::unique_ptr<asn1_context> sig_set(signed_data_seq->asn1_set_get());
+  if (sig_set == nullptr) {
+    return false;
+  }
+
+  std::unique_ptr<asn1_context> sig_seq(sig_set->asn1_sequence_get());
+  if (sig_seq == nullptr || !sig_seq->asn1_sequence_next() || !sig_seq->asn1_sequence_next() ||
+      !sig_seq->asn1_sequence_next() || !sig_seq->asn1_sequence_next()) {
+    return false;
+  }
+
+  const uint8_t* sig_der_ptr;
+  size_t sig_der_length;
+  if (!sig_seq->asn1_octet_string_get(&sig_der_ptr, &sig_der_length)) {
+    return false;
+  }
+
+  sig_der->resize(sig_der_length);
+  std::copy(sig_der_ptr, sig_der_ptr + sig_der_length, sig_der->begin());
+  return true;
+}
+
+int verify_file(VerifierInterface* package, const std::vector<Certificate>& keys) {
+  CHECK(package);
+  package->SetProgress(0.0);
+
+  // An archive with a whole-file signature will end in six bytes:
+  //
+  //   (2-byte signature start) $ff $ff (2-byte comment size)
+  //
+  // (As far as the ZIP format is concerned, these are part of the archive comment.) We start by
+  // reading this footer, this tells us how far back from the end we have to start reading to find
+  // the whole comment.
+
+#define FOOTER_SIZE 6
+  uint64_t length = package->GetPackageSize();
+
+  if (length < FOOTER_SIZE) {
+    LOG(ERROR) << "not big enough to contain footer";
+    return VERIFY_FAILURE;
+  }
+
+  uint8_t footer[FOOTER_SIZE];
+  if (!package->ReadFullyAtOffset(footer, FOOTER_SIZE, length - FOOTER_SIZE)) {
+    LOG(ERROR) << "Failed to read footer";
+    return VERIFY_FAILURE;
+  }
+
+  if (footer[2] != 0xff || footer[3] != 0xff) {
+    LOG(ERROR) << "footer is wrong";
+    return VERIFY_FAILURE;
+  }
+
+  size_t comment_size = footer[4] + (footer[5] << 8);
+  size_t signature_start = footer[0] + (footer[1] << 8);
+  LOG(INFO) << "comment is " << comment_size << " bytes; signature is " << signature_start
+            << " bytes from end";
+
+  if (signature_start > comment_size) {
+    LOG(ERROR) << "signature start: " << signature_start
+               << " is larger than comment size: " << comment_size;
+    return VERIFY_FAILURE;
+  }
+
+  if (signature_start <= FOOTER_SIZE) {
+    LOG(ERROR) << "Signature start is in the footer";
+    return VERIFY_FAILURE;
+  }
+
+#define EOCD_HEADER_SIZE 22
+
+  // The end-of-central-directory record is 22 bytes plus any comment length.
+  size_t eocd_size = comment_size + EOCD_HEADER_SIZE;
+
+  if (length < eocd_size) {
+    LOG(ERROR) << "not big enough to contain EOCD";
+    return VERIFY_FAILURE;
+  }
+
+  // Determine how much of the file is covered by the signature. This is everything except the
+  // signature data and length, which includes all of the EOCD except for the comment length field
+  // (2 bytes) and the comment data.
+  uint64_t signed_len = length - eocd_size + EOCD_HEADER_SIZE - 2;
+
+  uint8_t eocd[eocd_size];
+  if (!package->ReadFullyAtOffset(eocd, eocd_size, length - eocd_size)) {
+    LOG(ERROR) << "Failed to read EOCD of " << eocd_size << " bytes";
+    return VERIFY_FAILURE;
+  }
+
+  // If this is really is the EOCD record, it will begin with the magic number $50 $4b $05 $06.
+  if (eocd[0] != 0x50 || eocd[1] != 0x4b || eocd[2] != 0x05 || eocd[3] != 0x06) {
+    LOG(ERROR) << "signature length doesn't match EOCD marker";
+    return VERIFY_FAILURE;
+  }
+
+  for (size_t i = 4; i < eocd_size - 3; ++i) {
+    if (eocd[i] == 0x50 && eocd[i + 1] == 0x4b && eocd[i + 2] == 0x05 && eocd[i + 3] == 0x06) {
+      // If the sequence $50 $4b $05 $06 appears anywhere after the real one, libziparchive will
+      // find the later (wrong) one, which could be exploitable. Fail the verification if this
+      // sequence occurs anywhere after the real one.
+      LOG(ERROR) << "EOCD marker occurs after start of EOCD";
+      return VERIFY_FAILURE;
+    }
+  }
+
+  bool need_sha1 = false;
+  bool need_sha256 = false;
+  for (const auto& key : keys) {
+    switch (key.hash_len) {
+      case SHA_DIGEST_LENGTH:
+        need_sha1 = true;
+        break;
+      case SHA256_DIGEST_LENGTH:
+        need_sha256 = true;
+        break;
+    }
+  }
+
+  SHA_CTX sha1_ctx;
+  SHA256_CTX sha256_ctx;
+  SHA1_Init(&sha1_ctx);
+  SHA256_Init(&sha256_ctx);
+
+  std::vector<HasherUpdateCallback> hashers;
+  if (need_sha1) {
+    hashers.emplace_back(
+        std::bind(&SHA1_Update, &sha1_ctx, std::placeholders::_1, std::placeholders::_2));
+  }
+  if (need_sha256) {
+    hashers.emplace_back(
+        std::bind(&SHA256_Update, &sha256_ctx, std::placeholders::_1, std::placeholders::_2));
+  }
+
+  double frac = -1.0;
+  uint64_t so_far = 0;
+  while (so_far < signed_len) {
+    // On a Nexus 5X, experiment showed 16MiB beat 1MiB by 6% faster for a 1196MiB full OTA and
+    // 60% for an 89MiB incremental OTA. http://b/28135231.
+    uint64_t read_size = std::min<uint64_t>(signed_len - so_far, 16 * MiB);
+    package->UpdateHashAtOffset(hashers, so_far, read_size);
+    so_far += read_size;
+
+    double f = so_far / static_cast<double>(signed_len);
+    if (f > frac + 0.02 || read_size == so_far) {
+      package->SetProgress(f);
+      frac = f;
+    }
+  }
+
+  uint8_t sha1[SHA_DIGEST_LENGTH];
+  SHA1_Final(sha1, &sha1_ctx);
+  uint8_t sha256[SHA256_DIGEST_LENGTH];
+  SHA256_Final(sha256, &sha256_ctx);
+
+  const uint8_t* signature = eocd + eocd_size - signature_start;
+  size_t signature_size = signature_start - FOOTER_SIZE;
+
+  LOG(INFO) << "signature (offset: " << std::hex << (length - signature_start)
+            << ", length: " << signature_size << "): " << print_hex(signature, signature_size);
+
+  std::vector<uint8_t> sig_der;
+  if (!read_pkcs7(signature, signature_size, &sig_der)) {
+    LOG(ERROR) << "Could not find signature DER block";
+    return VERIFY_FAILURE;
+  }
+
+  // Check to make sure at least one of the keys matches the signature. Since any key can match,
+  // we need to try each before determining a verification failure has happened.
+  size_t i = 0;
+  for (const auto& key : keys) {
+    const uint8_t* hash;
+    int hash_nid;
+    switch (key.hash_len) {
+      case SHA_DIGEST_LENGTH:
+        hash = sha1;
+        hash_nid = NID_sha1;
+        break;
+      case SHA256_DIGEST_LENGTH:
+        hash = sha256;
+        hash_nid = NID_sha256;
+        break;
+      default:
+        continue;
+    }
+
+    // The 6 bytes is the "(signature_start) $ff $ff (comment_size)" that the signing tool appends
+    // after the signature itself.
+    if (key.key_type == Certificate::KEY_TYPE_RSA) {
+      if (!RSA_verify(hash_nid, hash, key.hash_len, sig_der.data(), sig_der.size(),
+                      key.rsa.get())) {
+        LOG(INFO) << "failed to verify against RSA key " << i;
+        continue;
+      }
+
+      LOG(INFO) << "whole-file signature verified against RSA key " << i;
+      return VERIFY_SUCCESS;
+    } else if (key.key_type == Certificate::KEY_TYPE_EC && key.hash_len == SHA256_DIGEST_LENGTH) {
+      if (!ECDSA_verify(0, hash, key.hash_len, sig_der.data(), sig_der.size(), key.ec.get())) {
+        LOG(INFO) << "failed to verify against EC key " << i;
+        continue;
+      }
+
+      LOG(INFO) << "whole-file signature verified against EC key " << i;
+      return VERIFY_SUCCESS;
+    } else {
+      LOG(INFO) << "Unknown key type " << key.key_type;
+    }
+    i++;
+  }
+
+  if (need_sha1) {
+    LOG(INFO) << "SHA-1 digest: " << print_hex(sha1, SHA_DIGEST_LENGTH);
+  }
+  if (need_sha256) {
+    LOG(INFO) << "SHA-256 digest: " << print_hex(sha256, SHA256_DIGEST_LENGTH);
+  }
+  LOG(ERROR) << "failed to verify whole-file signature";
+  return VERIFY_FAILURE;
+}
+
+static std::vector<Certificate> IterateZipEntriesAndSearchForKeys(const ZipArchiveHandle& handle) {
+  void* cookie;
+  int32_t iter_status = StartIteration(handle, &cookie, "", "x509.pem");
+  if (iter_status != 0) {
+    LOG(ERROR) << "Failed to iterate over entries in the certificate zipfile: "
+               << ErrorCodeString(iter_status);
+    return {};
+  }
+
+  std::vector<Certificate> result;
+
+  std::string_view name;
+  ZipEntry64 entry;
+  while ((iter_status = Next(cookie, &entry, &name)) == 0) {
+    if (entry.uncompressed_length > std::numeric_limits<size_t>::max()) {
+      LOG(ERROR) << "Failed to extract " << name
+                 << " because's uncompressed size exceeds size of address space. "
+                 << entry.uncompressed_length;
+      return {};
+    }
+    std::vector<uint8_t> pem_content(entry.uncompressed_length);
+    if (int32_t extract_status =
+            ExtractToMemory(handle, &entry, pem_content.data(), pem_content.size());
+        extract_status != 0) {
+      LOG(ERROR) << "Failed to extract " << name;
+      return {};
+    }
+
+    Certificate cert(0, Certificate::KEY_TYPE_RSA, nullptr, nullptr);
+    // Aborts the parsing if we fail to load one of the key file.
+    if (!LoadCertificateFromBuffer(pem_content, &cert)) {
+      LOG(ERROR) << "Failed to load keys from " << name;
+      return {};
+    }
+
+    result.emplace_back(std::move(cert));
+  }
+
+  if (iter_status != -1) {
+    LOG(ERROR) << "Error while iterating over zip entries: " << ErrorCodeString(iter_status);
+    return {};
+  }
+
+  return result;
+}
+
+std::vector<Certificate> LoadKeysFromZipfile(const std::string& zip_name) {
+  ZipArchiveHandle handle;
+  if (int32_t open_status = OpenArchive(zip_name.c_str(), &handle); open_status != 0) {
+    LOG(ERROR) << "Failed to open " << zip_name << ": " << ErrorCodeString(open_status);
+    return {};
+  }
+
+  std::vector<Certificate> result = IterateZipEntriesAndSearchForKeys(handle);
+  CloseArchive(handle);
+  return result;
+}
+
+bool CheckRSAKey(const std::unique_ptr<RSA, RSADeleter>& rsa) {
+  if (!rsa) {
+    return false;
+  }
+
+  const BIGNUM* out_n;
+  const BIGNUM* out_e;
+  RSA_get0_key(rsa.get(), &out_n, &out_e, nullptr /* private exponent */);
+  auto modulus_bits = BN_num_bits(out_n);
+  if (modulus_bits != 2048 && modulus_bits != 4096) {
+    LOG(ERROR) << "Modulus should be 2048 or 4096 bits long, actual: " << modulus_bits;
+    return false;
+  }
+
+  BN_ULONG exponent = BN_get_word(out_e);
+  if (exponent != 3 && exponent != 65537) {
+    LOG(ERROR) << "Public exponent should be 3 or 65537, actual: " << exponent;
+    return false;
+  }
+
+  return true;
+}
+
+bool CheckECKey(const std::unique_ptr<EC_KEY, ECKEYDeleter>& ec_key) {
+  if (!ec_key) {
+    return false;
+  }
+
+  const EC_GROUP* ec_group = EC_KEY_get0_group(ec_key.get());
+  if (!ec_group) {
+    LOG(ERROR) << "Failed to get the ec_group from the ec_key";
+    return false;
+  }
+  auto degree = EC_GROUP_get_degree(ec_group);
+  if (degree != 256) {
+    LOG(ERROR) << "Field size of the ec key should be 256 bits long, actual: " << degree;
+    return false;
+  }
+
+  return true;
+}
+
+bool LoadCertificateFromBuffer(const std::vector<uint8_t>& pem_content, Certificate* cert) {
+  std::unique_ptr<BIO, decltype(&BIO_free)> content(
+      BIO_new_mem_buf(pem_content.data(), pem_content.size()), BIO_free);
+
+  std::unique_ptr<X509, decltype(&X509_free)> x509(
+      PEM_read_bio_X509(content.get(), nullptr, nullptr, nullptr), X509_free);
+  if (!x509) {
+    LOG(ERROR) << "Failed to read x509 certificate";
+    return false;
+  }
+
+  int nid = X509_get_signature_nid(x509.get());
+  switch (nid) {
+    // SignApk has historically accepted md5WithRSA certificates, but treated them as
+    // sha1WithRSA anyway. Continue to do so for backwards compatibility.
+    case NID_md5WithRSA:
+    case NID_md5WithRSAEncryption:
+    case NID_sha1WithRSA:
+    case NID_sha1WithRSAEncryption:
+      cert->hash_len = SHA_DIGEST_LENGTH;
+      break;
+    case NID_sha256WithRSAEncryption:
+    case NID_ecdsa_with_SHA256:
+      cert->hash_len = SHA256_DIGEST_LENGTH;
+      break;
+    default:
+      LOG(ERROR) << "Unrecognized signature nid " << OBJ_nid2ln(nid);
+      return false;
+  }
+
+  std::unique_ptr<EVP_PKEY, decltype(&EVP_PKEY_free)> public_key(X509_get_pubkey(x509.get()),
+                                                                 EVP_PKEY_free);
+  if (!public_key) {
+    LOG(ERROR) << "Failed to extract the public key from x509 certificate";
+    return false;
+  }
+
+  int key_type = EVP_PKEY_id(public_key.get());
+  if (key_type == EVP_PKEY_RSA) {
+    cert->key_type = Certificate::KEY_TYPE_RSA;
+    cert->ec.reset();
+    cert->rsa.reset(EVP_PKEY_get1_RSA(public_key.get()));
+    if (!cert->rsa || !CheckRSAKey(cert->rsa)) {
+      LOG(ERROR) << "Failed to validate the rsa key info from public key";
+      return false;
+    }
+  } else if (key_type == EVP_PKEY_EC) {
+    cert->key_type = Certificate::KEY_TYPE_EC;
+    cert->rsa.reset();
+    cert->ec.reset(EVP_PKEY_get1_EC_KEY(public_key.get()));
+    if (!cert->ec || !CheckECKey(cert->ec)) {
+      LOG(ERROR) << "Failed to validate the ec key info from the public key";
+      return false;
+    }
+  } else {
+    LOG(ERROR) << "Unrecognized public key type " << OBJ_nid2ln(key_type);
+    return false;
+  }
+
+  return true;
+}