Merge changes from topic "fec_avb" into rvc-dev

* changes:
  Allow building libfec without libavb
  Suport parsing hashtree and ecc data from avb

10 files changed, 389 insertions, 7 deletions

diff --git a/libfec/Android.bp b/libfec/Android.bp
index 78f2fedd..3da6fe7c 100644
--- a/libfec/Android.bp
+++ b/libfec/Android.bp
@@ -1,16 +1,22 @@
 // Copyright 2015 The Android Open Source Project
 
-cc_library {
-    name: "libfec",
-    host_supported: true,
-    recovery_available: true,
+cc_defaults {
+    name: "libfec_default",
+
+    cflags: [
+        "-Wall",
+        "-Werror",
+        "-O3",
+        "-D_LARGEFILE64_SOURCE",
+    ],
+
     srcs: [
         "fec_open.cpp",
         "fec_read.cpp",
         "fec_verity.cpp",
         "fec_process.cpp",
     ],
-    cflags: ["-Wall", "-Werror", "-O3", "-D_LARGEFILE64_SOURCE"],
+
     export_include_dirs: ["include"],
     // Exported header include/fec/io.h includes crypto_utils headers.
     export_shared_lib_headers: ["libcrypto_utils"],
@@ -30,7 +36,10 @@ cc_library {
 
     target: {
         host: {
-            cflags: ["-D_GNU_SOURCE", "-DFEC_NO_KLOG"]
+            cflags: [
+                "-D_GNU_SOURCE",
+                "-DFEC_NO_KLOG",
+            ],
         },
         linux_glibc: {
             sanitize: {
@@ -39,3 +48,28 @@ cc_library {
         },
     },
 }
+
+cc_library {
+    name: "libfec",
+    defaults: ["libfec_default"],
+    host_supported: true,
+    recovery_available: true,
+
+    target: {
+        linux: {
+            srcs: [
+                "avb_utils.cpp",
+            ],
+            static_libs: [
+                "libavb",
+            ],
+        },
+
+        // libavb isn't available on mac.
+        darwin: {
+            srcs: [
+                "avb_utils_stub.cpp",
+            ],
+        },
+    },
+}
diff --git a/libfec/avb_utils.cpp b/libfec/avb_utils.cpp
new file mode 100644
index 00000000..8913f2a1
--- /dev/null
+++ b/libfec/avb_utils.cpp
@@ -0,0 +1,160 @@
+/*
+ * Copyright (C) 2020 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 "avb_utils.h"
+
+#include <android-base/strings.h>
+#include <libavb/libavb.h>
+
+#include "fec_private.h"
+
+int parse_vbmeta_from_footer(fec_handle *f, std::vector<uint8_t> *vbmeta) {
+    if (f->size <= AVB_FOOTER_SIZE) {
+        debug("file size not large enough to be avb images:" PRIu64, f->size);
+        return -1;
+    }
+
+    AvbFooter footer_read;
+    if (!raw_pread(f->fd, &footer_read, AVB_FOOTER_SIZE,
+                   f->size - AVB_FOOTER_SIZE)) {
+        error("failed to read footer: %s", strerror(errno));
+        return -1;
+    }
+
+    AvbFooter footer;
+    if (!avb_footer_validate_and_byteswap(&footer_read, &footer)) {
+        debug("invalid avb footer");
+        return -1;
+    }
+    uint64_t vbmeta_offset = footer.vbmeta_offset;
+    uint64_t vbmeta_size = footer.vbmeta_size;
+    check(vbmeta_offset <= f->size - sizeof(footer) - vbmeta_size);
+
+    std::vector<uint8_t> vbmeta_data(vbmeta_size, 0);
+    // TODO(xunchang) handle the sparse image with libsparse.
+    if (!raw_pread(f->fd, vbmeta_data.data(), vbmeta_data.size(),
+                   vbmeta_offset)) {
+        error("failed to read avb vbmeta: %s", strerror(errno));
+        return -1;
+    }
+
+    if (auto status = avb_vbmeta_image_verify(
+            vbmeta_data.data(), vbmeta_data.size(), nullptr, nullptr);
+        status != AVB_VBMETA_VERIFY_RESULT_OK &&
+        status != AVB_VBMETA_VERIFY_RESULT_OK_NOT_SIGNED) {
+        error("failed to verify avb vbmeta, status: %d", status);
+        return -1;
+    }
+    *vbmeta = std::move(vbmeta_data);
+    return 0;
+}
+
+int parse_avb_image(fec_handle *f, const std::vector<uint8_t> &vbmeta) {
+    // TODO(xunchang) check if avb verification or hashtree is disabled.
+
+    // Look for the hashtree descriptor, we expect exactly one descriptor in
+    // vbmeta.
+    // TODO(xunchang) handle the image with AvbHashDescriptor.
+    auto parse_descriptor = [](const AvbDescriptor *descriptor,
+                               void *user_data) {
+        if (descriptor &&
+            avb_be64toh(descriptor->tag) == AVB_DESCRIPTOR_TAG_HASHTREE) {
+            auto desp = static_cast<const AvbDescriptor **>(user_data);
+            *desp = descriptor;
+            return false;
+        }
+        return true;
+    };
+
+    const AvbHashtreeDescriptor *hashtree_descriptor_ptr = nullptr;
+    avb_descriptor_foreach(vbmeta.data(), vbmeta.size(), parse_descriptor,
+                           &hashtree_descriptor_ptr);
+
+    AvbHashtreeDescriptor hashtree_descriptor;
+    if (!avb_hashtree_descriptor_validate_and_byteswap(hashtree_descriptor_ptr,
+                                                       &hashtree_descriptor)) {
+        error("failed to verify avb hashtree descriptor");
+        return -1;
+    }
+
+    // The partition name, salt, root append right after the hashtree
+    // descriptor.
+    auto read_ptr = reinterpret_cast<const uint8_t *>(hashtree_descriptor_ptr);
+    // Calculate the offset with respect to the vbmeta; and check both the
+    // salt & root are within the range.
+    uint32_t salt_offset =
+        sizeof(AvbHashtreeDescriptor) + hashtree_descriptor.partition_name_len;
+    uint32_t root_offset = salt_offset + hashtree_descriptor.salt_len;
+    check(hashtree_descriptor.salt_len < vbmeta.size());
+    check(salt_offset < vbmeta.size() - hashtree_descriptor.salt_len);
+    check(hashtree_descriptor.root_digest_len < vbmeta.size());
+    check(root_offset < vbmeta.size() - hashtree_descriptor.root_digest_len);
+    std::vector<uint8_t> salt(
+        read_ptr + salt_offset,
+        read_ptr + salt_offset + hashtree_descriptor.salt_len);
+    std::vector<uint8_t> root_hash(
+        read_ptr + root_offset,
+        read_ptr + root_offset + hashtree_descriptor.root_digest_len);
+
+    // Expect the AVB image has the format:
+    // 1. hashtree
+    // 2. ecc data
+    // 3. vbmeta
+    // 4. avb footer
+    check(hashtree_descriptor.fec_offset ==
+          hashtree_descriptor.tree_offset + hashtree_descriptor.tree_size);
+    check(hashtree_descriptor.fec_offset <=
+          f->size - hashtree_descriptor.fec_size);
+
+    f->data_size = hashtree_descriptor.fec_offset;
+
+    f->ecc.blocks = fec_div_round_up(f->data_size, FEC_BLOCKSIZE);
+    f->ecc.rounds = fec_div_round_up(f->ecc.blocks, f->ecc.rsn);
+    f->ecc.size = hashtree_descriptor.fec_size;
+    f->ecc.start = hashtree_descriptor.fec_offset;
+    // TODO(xunchang) verify the integrity of the ecc data.
+    f->ecc.valid = true;
+
+    std::string hash_algorithm =
+        reinterpret_cast<char *>(hashtree_descriptor.hash_algorithm);
+    int nid = -1;
+    if (android::base::EqualsIgnoreCase(hash_algorithm, "sha1")) {
+        nid = NID_sha1;
+    } else if (android::base::EqualsIgnoreCase(hash_algorithm, "sha256")) {
+        nid = NID_sha256;
+    } else {
+        error("unsupported hash algorithm %s", hash_algorithm.c_str());
+    }
+
+    hashtree_info hashtree;
+    hashtree.initialize(hashtree_descriptor.tree_offset,
+                        hashtree_descriptor.tree_offset / FEC_BLOCKSIZE, salt,
+                        nid);
+    if (hashtree.verify_tree(f, root_hash.data()) != 0) {
+        error("failed to verify hashtree");
+        return -1;
+    }
+
+    // We have validate the hashtree,
+    f->data_size = hashtree.hash_start;
+    f->avb = {
+        .valid = true,
+        .vbmeta = vbmeta,
+        .hashtree = std::move(hashtree),
+    };
+
+    return 0;
+}
diff --git a/libfec/avb_utils.h b/libfec/avb_utils.h
new file mode 100644
index 00000000..78254508
--- /dev/null
+++ b/libfec/avb_utils.h
@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2020 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 <vector>
+
+struct fec_handle;
+
+// Checks if there is a valid AVB footer in the end of the image. If so, parses
+// the contents of vbmeta struct from the given AVB footer. Returns 0 on
+// success.
+int parse_vbmeta_from_footer(fec_handle *f, std::vector<uint8_t> *vbmeta);
+
+// Parses the AVB vbmeta for the information of hashtree and fec data.
+int parse_avb_image(fec_handle *f, const std::vector<uint8_t> &vbmeta);
diff --git a/libfec/avb_utils_stub.cpp b/libfec/avb_utils_stub.cpp
new file mode 100644
index 00000000..0b6061e5
--- /dev/null
+++ b/libfec/avb_utils_stub.cpp
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2020 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 "avb_utils.h"
+
+int parse_vbmeta_from_footer(fec_handle* /* f */,
+                             std::vector<uint8_t> * /* vbmeta */) {
+    return -1;
+}
+
+int parse_avb_image(fec_handle* /* f */,
+                    const std::vector<uint8_t>& /* vbmeta */) {
+    return -1;
+}
diff --git a/libfec/fec_open.cpp b/libfec/fec_open.cpp
index 18731f21..fe458097 100644
--- a/libfec/fec_open.cpp
+++ b/libfec/fec_open.cpp
@@ -29,6 +29,7 @@
     #define fdatasync(fd) fcntl((fd), F_FULLFSYNC)
 #endif
 
+#include "avb_utils.h"
 #include "fec_private.h"
 
 /* used by `find_offset'; returns metadata size for a file size `size' and
@@ -546,6 +547,23 @@ int fec_open(struct fec_handle **handle, const char *path, int mode, int flags,
 
     f->data_size = f->size; /* until ecc and/or verity are loaded */
 
+    // Don't parse the avb image if FEC_NO_AVB is set. It's used when libavb is
+    // not supported on mac.
+    std::vector<uint8_t> vbmeta;
+    if (parse_vbmeta_from_footer(f.get(), &vbmeta) == 0) {
+        if (parse_avb_image(f.get(), vbmeta) != 0) {
+            error("failed to parse avb image.");
+            return -1;
+        }
+
+        *handle = f.release();
+        return 0;
+    }
+    // TODO(xunchang) For android, handle the case when vbmeta is in a separate
+    // image. We could use avb_slot_verify() && AvbOps from libavb_user.
+
+    // Fall back to use verity format.
+
     if (load_ecc(f.get()) == -1) {
         debug("error-correcting codes not found from '%s'", path);
     }
diff --git a/libfec/fec_private.h b/libfec/fec_private.h
index 62687994..b28c4294 100644
--- a/libfec/fec_private.h
+++ b/libfec/fec_private.h
@@ -124,6 +124,12 @@ struct verity_info {
     verity_header ecc_header;
 };
 
+struct avb_info {
+    bool valid = false;
+    std::vector<uint8_t> vbmeta;
+    hashtree_info hashtree;
+};
+
 struct fec_handle {
     ecc_info ecc;
     int fd;
@@ -134,10 +140,12 @@ struct fec_handle {
     uint64_t data_size;
     uint64_t pos;
     uint64_t size;
+    // TODO(xunchang) switch to std::optional
     verity_info verity;
+    avb_info avb;
 
     hashtree_info hashtree() const {
-        return verity.hashtree;
+        return avb.valid ? avb.hashtree : verity.hashtree;
     }
 };
 
diff --git a/libfec/test/Android.bp b/libfec/test/Android.bp
index 1bbad077..75182a27 100644
--- a/libfec/test/Android.bp
+++ b/libfec/test/Android.bp
@@ -24,6 +24,7 @@ cc_test_host {
     static_libs: [
         "libfec",
         "libfec_rs",
+        "libavb",
         "libcrypto_utils",
         "libcrypto",
         "libext4_utils",
@@ -47,12 +48,14 @@ cc_test_host {
 
     gtest: true,
     required: [
+        "avbtool",
         "fec",
     ],
     static_libs: [
         "libverity_tree",
         "libfec",
         "libfec_rs",
+        "libavb",
         "libcrypto_utils",
         "libext4_utils",
         "libsquashfs_utils",
diff --git a/libfec/test/fec_unittest.cpp b/libfec/test/fec_unittest.cpp
index ca5d91a8..421eb501 100644
--- a/libfec/test/fec_unittest.cpp
+++ b/libfec/test/fec_unittest.cpp
@@ -102,6 +102,20 @@ class FecUnitTest : public ::testing::Test {
         ASSERT_EQ(0, std::system(android::base::Join(cmd, ' ').c_str()));
     }
 
+    void AddAvbHashtreeFooter(const std::string &image_name,
+                              std::string algorithm = "sha256") {
+        salt_ = std::vector<uint8_t>(64, 10);
+        std::vector<std::string> cmd = {
+            "avbtool",          "add_hashtree_footer",
+            "--salt",           HashTreeBuilder::BytesArrayToString(salt_),
+            "--hash_algorithm", algorithm,
+            "--image",          image_name,
+        };
+        ASSERT_EQ(0, std::system(android::base::Join(cmd, ' ').c_str()));
+
+        BuildHashtree(algorithm);
+    }
+
     std::vector<uint8_t> image_;
     std::vector<uint8_t> salt_;
     std::vector<uint8_t> root_hash_;
@@ -202,3 +216,85 @@ TEST_F(FecUnitTest, VerityImage_FecRead) {
     ASSERT_EQ(1024, fec_pread(handle, read_data.data(), 1024, corrupt_offset));
     ASSERT_EQ(std::vector<uint8_t>(1024, 255), read_data);
 }
+
+TEST_F(FecUnitTest, LoadAvbImage_HashtreeFooter) {
+    TemporaryFile avb_image;
+    ASSERT_TRUE(
+        android::base::WriteFully(avb_image.fd, image_.data(), image_.size()));
+    AddAvbHashtreeFooter(avb_image.path);
+
+    struct fec_handle *handle = nullptr;
+    ASSERT_EQ(0, fec_open(&handle, avb_image.path, O_RDWR, FEC_FS_EXT4, 2));
+    std::unique_ptr<fec_handle> guard(handle);
+
+    ASSERT_EQ(1024 * 1024, handle->data_size);  // filesystem size
+
+    ASSERT_TRUE(handle->avb.valid);
+
+    // check the hashtree.
+    ASSERT_EQ(salt_, handle->hashtree().salt);
+    ASSERT_EQ(1024 * 1024, handle->hashtree().hash_start);
+    // the fec hashtree only stores the hash of the lowest level.
+    ASSERT_EQ(std::vector<uint8_t>(hashtree_content_.begin() + 4096,
+                                   hashtree_content_.end()),
+              handle->hashtree().hash_data);
+    uint64_t hash_size =
+        verity_get_size(handle->hashtree().data_blocks * FEC_BLOCKSIZE, nullptr,
+                        nullptr, SHA256_DIGEST_LENGTH);
+    ASSERT_EQ(hashtree_content_.size(), hash_size);
+
+    fec_ecc_metadata ecc_metadata{};
+    ASSERT_EQ(0, fec_ecc_get_metadata(handle, &ecc_metadata));
+    ASSERT_TRUE(ecc_metadata.valid);
+    ASSERT_EQ(1024 * 1024 + hash_size, ecc_metadata.start);
+    ASSERT_EQ(259, ecc_metadata.blocks);
+}
+
+TEST_F(FecUnitTest, LoadAvbImage_CorrectHashtree) {
+    TemporaryFile avb_image;
+    ASSERT_TRUE(
+        android::base::WriteFully(avb_image.fd, image_.data(), image_.size()));
+    AddAvbHashtreeFooter(avb_image.path);
+
+    uint64_t corrupt_offset = 1024 * 1024 + 2 * 4096 + 50;
+    ASSERT_EQ(corrupt_offset, lseek64(avb_image.fd, corrupt_offset, 0));
+    std::vector<uint8_t> corruption(20, 5);
+    ASSERT_TRUE(android::base::WriteFully(avb_image.fd, corruption.data(),
+                                          corruption.size()));
+
+    struct fec_handle *handle = nullptr;
+    ASSERT_EQ(0, fec_open(&handle, avb_image.path, O_RDWR, FEC_FS_EXT4, 2));
+    std::unique_ptr<fec_handle> guard(handle);
+
+    ASSERT_EQ(1024 * 1024, handle->data_size);  // filesystem size
+    fec_ecc_metadata ecc_metadata{};
+    ASSERT_EQ(0, fec_ecc_get_metadata(handle, &ecc_metadata));
+    ASSERT_TRUE(ecc_metadata.valid);
+}
+
+TEST_F(FecUnitTest, AvbImage_FecRead) {
+    TemporaryFile avb_image;
+    ASSERT_TRUE(
+        android::base::WriteFully(avb_image.fd, image_.data(), image_.size()));
+    AddAvbHashtreeFooter(avb_image.path, "sha1");
+
+    uint64_t corrupt_offset = 4096 * 10;
+    ASSERT_EQ(corrupt_offset, lseek64(avb_image.fd, corrupt_offset, 0));
+    std::vector<uint8_t> corruption(50, 99);
+    ASSERT_TRUE(android::base::WriteFully(avb_image.fd, corruption.data(),
+                                          corruption.size()));
+
+    std::vector<uint8_t> read_data(1024, 0);
+    struct fec_handle *handle = nullptr;
+    ASSERT_EQ(0, fec_open(&handle, avb_image.path, O_RDWR, FEC_FS_EXT4, 2));
+    std::unique_ptr<fec_handle> guard(handle);
+
+    // Verify the hashtree has the expected content.
+    ASSERT_EQ(std::vector<uint8_t>(hashtree_content_.begin() + 4096,
+                                   hashtree_content_.end()),
+              handle->hashtree().hash_data);
+
+    // Verify the corruption gets corrected.
+    ASSERT_EQ(1024, fec_pread(handle, read_data.data(), 1024, corrupt_offset));
+    ASSERT_EQ(std::vector<uint8_t>(1024, 10), read_data);
+}
diff --git a/verity/Android.bp b/verity/Android.bp
index 1158c77d..5d0a80c0 100644
--- a/verity/Android.bp
+++ b/verity/Android.bp
@@ -51,6 +51,7 @@ cc_binary_host {
     static_libs: [
         "libfec",
         "libfec_rs",
+        "libavb",
         "libcrypto_utils",
         "libcrypto",
         "libext4_utils",
diff --git a/verity/fec/Android.bp b/verity/fec/Android.bp
index a6bcef95..4bcecb09 100644
--- a/verity/fec/Android.bp
+++ b/verity/fec/Android.bp
@@ -7,6 +7,11 @@ cc_binary_host {
                 misc_undefined: ["integer"],
             },
         },
+        linux: {
+            static_libs: [
+                "libavb",
+            ],
+        },
     },
 
     srcs: [