Set libavb version into system property for Treble OTA

Set ro.boot.avb_version to "AVB_VERSION_MAJOR.AVB_VERSION_MINOR".
During Treble OTA match, the major version must be the same as that in
the avb metadata on disk, while the minor version can be equal or
greater to that in the avb metadata on disk.

See how avb versioning work on the following link:

  https://android-review.googlesource.com/#/c/342757/

Also renames AvbHashtreeDisabled() -> hashtree_disabled().

Bug: 35322304
Test: Early mount with AVB, checks [ro.boot.avb_version]: [1.0] exists.
Test: Not enable AVB, checks [ro.boot.avb_version] doesn't exists.

Change-Id: I5aaf476ca53c4fe817779518ba14b68ebcfdc6d6

3 files changed, 12 insertions, 3 deletions

diff --git a/fs_mgr/fs_mgr_avb.cpp b/fs_mgr/fs_mgr_avb.cpp
index 7c82bb1e6a..83bf8a7786 100644
--- a/fs_mgr/fs_mgr_avb.cpp
+++ b/fs_mgr/fs_mgr_avb.cpp
@@ -493,6 +493,10 @@ FsManagerAvbUniquePtr FsManagerAvbHandle::Open(const std::string& device_file_by
         return nullptr;
     }
 
+    // Sets the MAJOR.MINOR for init to set it into "ro.boot.avb_version".
+    avb_handle->avb_version_ =
+        android::base::StringPrintf("%d.%d", AVB_VERSION_MAJOR, AVB_VERSION_MINOR);
+
     // Verifies vbmeta images against the digest passed from bootloader.
     if (!avb_verifier->VerifyVbmetaImages(*avb_handle->avb_slot_data_)) {
         LERROR << "VerifyVbmetaImages failed";
diff --git a/fs_mgr/include/fs_mgr_avb.h b/fs_mgr/include/fs_mgr_avb.h
index 526a5ce065..a66ff42cca 100644
--- a/fs_mgr/include/fs_mgr_avb.h
+++ b/fs_mgr/include/fs_mgr_avb.h
@@ -72,7 +72,8 @@ class FsManagerAvbHandle {
     // Otherwise, returns false.
     bool SetUpAvb(fstab_rec* fstab_entry, bool wait_for_verity_dev);
 
-    bool AvbHashtreeDisabled() { return status_ == kFsManagerAvbHandleHashtreeDisabled; }
+    bool hashtree_disabled() const { return status_ == kFsManagerAvbHandleHashtreeDisabled; }
+    const std::string& avb_version() const { return avb_version_; }
 
     FsManagerAvbHandle(const FsManagerAvbHandle&) = delete;             // no copy
     FsManagerAvbHandle& operator=(const FsManagerAvbHandle&) = delete;  // no assignment
@@ -92,6 +93,7 @@ class FsManagerAvbHandle {
   private:
     AvbSlotVerifyData* avb_slot_data_;
     FsManagerAvbHandleStatus status_;
+    std::string avb_version_;
 };
 
 #endif /* __CORE_FS_MGR_AVB_H */
diff --git a/init/init.cpp b/init/init.cpp
index 6c1c541282..181b18d0b4 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -1010,10 +1010,11 @@ static bool vboot_2_0_mount_partitions(const std::vector<fstab_rec*>& fstab_recs
         return false;
     }
 
+    setenv("INIT_AVB_VERSION", avb_handle->avb_version().c_str(), 1);
     for (auto rec : fstab_recs) {
         bool need_create_dm_device = false;
         if (fs_mgr_is_avb(rec)) {
-            if (avb_handle->AvbHashtreeDisabled()) {
+            if (avb_handle->hashtree_disabled()) {
                 LOG(INFO) << "avb hashtree disabled for '" << rec->mount_point << "'";
             } else if (avb_handle->SetUpAvb(rec, false /* wait_for_verity_dev */)) {
                 need_create_dm_device = true;
@@ -1362,12 +1363,14 @@ int main(int argc, char** argv) {
     property_set("ro.boottime.init.selinux", getenv("INIT_SELINUX_TOOK"));
 
     // Set libavb version for Framework-only OTA match in Treble build.
-    property_set("ro.boot.init.avb_version", std::to_string(AVB_MAJOR_VERSION).c_str());
+    const char* avb_version = getenv("INIT_AVB_VERSION");
+    if (avb_version) property_set("ro.boot.avb_version", avb_version);
 
     // Clean up our environment.
     unsetenv("INIT_SECOND_STAGE");
     unsetenv("INIT_STARTED_AT");
     unsetenv("INIT_SELINUX_TOOK");
+    unsetenv("INIT_AVB_VERSION");
 
     // Now set up SELinux for second stage.
     selinux_initialize(false);