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Commit 10bec65c authored by Tianjie's avatar Tianjie
Browse files

Dump the root digest of hashtree for dm-verity partitions 

It's requested by the partner engineering team to uniquely
identify a partition.

Bug: 197973981
Test: boot the device and check props
Change-Id: I0f7aa34dd0087f0698fe90b9df6c0eae06fc4f5d
parent c3f73cbd

fs_mgr/fs_mgr.cpp

+8 −7
Original line number Diff line number Diff line
@@ -2231,16 +2231,16 @@ bool fs_mgr_is_verity_enabled(const FstabEntry& entry) { 
    return false;

}



std::string fs_mgr_get_hashtree_algorithm(const android::fs_mgr::FstabEntry& entry) {

std::optional<HashtreeInfo> fs_mgr_get_hashtree_info(const android::fs_mgr::FstabEntry& entry) {

    if (!entry.fs_mgr_flags.verify && !entry.fs_mgr_flags.avb) {

        return "";

        return {};

    }

    DeviceMapper& dm = DeviceMapper::Instance();

    std::string device = GetVerityDeviceName(entry);



    std::vector<DeviceMapper::TargetInfo> table;

    if (dm.GetState(device) == DmDeviceState::INVALID || !dm.GetTableInfo(device, &table)) {

        return "";

        return {};

    }

    for (const auto& target : table) {

        if (strcmp(target.spec.target_type, "verity") != 0) {
@@ -2256,14 +2256,15 @@ std::string fs_mgr_get_hashtree_algorithm(const android::fs_mgr::FstabEntry& ent 
        std::vector<std::string> tokens = android::base::Split(target.data, " \t\r\n");

        if (tokens[0] != "0" && tokens[0] != "1") {

            LOG(WARNING) << "Unrecognized device mapper version in " << target.data;

            return "";

            return {};

        }



        // Hashtree algorithm is the 8th token in the output

        return android::base::Trim(tokens[7]);

        // Hashtree algorithm & root digest are the 8th & 9th token in the output.

        return HashtreeInfo{.algorithm = android::base::Trim(tokens[7]),

                            .root_digest = android::base::Trim(tokens[8])};

    }



    return "";

    return {};

}



bool fs_mgr_verity_is_check_at_most_once(const android::fs_mgr::FstabEntry& entry) {

fs_mgr/include/fs_mgr.h

+11 −3
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#include <linux/dm-ioctl.h>



#include <functional>

#include <optional>

#include <string>



#include <fstab/fstab.h>
@@ -68,6 +69,13 @@ struct MountAllResult { 
    bool userdata_mounted;

};



struct HashtreeInfo {

    // The hash algorithm used to build the merkle tree.

    std::string algorithm;

    // The root digest of the merkle tree.

    std::string root_digest;

};



// fs_mgr_mount_all() updates fstab entries that reference device-mapper.

// Returns a |MountAllResult|. The first element is one of the FS_MNG_MNTALL_* return codes

// defined above, and the second element tells whether this call to fs_mgr_mount_all was responsible
@@ -88,9 +96,9 @@ int fs_mgr_do_tmpfs_mount(const char *n_name); 
bool fs_mgr_load_verity_state(int* mode);

// Returns true if verity is enabled on this particular FstabEntry.

bool fs_mgr_is_verity_enabled(const android::fs_mgr::FstabEntry& entry);

// Returns the hash algorithm used to build the hashtree of this particular FstabEntry. Returns an

// empty string if the input isn't a dm-verity entry, or if there is an error.

std::string fs_mgr_get_hashtree_algorithm(const android::fs_mgr::FstabEntry& entry);

// Returns the verity hashtree information of this particular FstabEntry. Returns std::nullopt

// if the input isn't a dm-verity entry, or if there is an error.

std::optional<HashtreeInfo> fs_mgr_get_hashtree_info(const android::fs_mgr::FstabEntry& entry);



bool fs_mgr_swapon_all(const android::fs_mgr::Fstab& fstab);

bool fs_mgr_update_logical_partition(android::fs_mgr::FstabEntry* entry);

init/builtins.cpp

+5 −3
Original line number Diff line number Diff line
@@ -894,9 +894,11 @@ static Result<void> do_verity_update_state(const BuiltinArguments& args) { 
        std::string partition = entry.mount_point == "/" ? "system" : Basename(entry.mount_point);

        SetProperty("partition." + partition + ".verified", std::to_string(mode));



        std::string hash_alg = fs_mgr_get_hashtree_algorithm(entry);

        if (!hash_alg.empty()) {

            SetProperty("partition." + partition + ".verified.hash_alg", hash_alg);

        auto hashtree_info = fs_mgr_get_hashtree_info(entry);

        if (hashtree_info) {

            SetProperty("partition." + partition + ".verified.hash_alg", hashtree_info->algorithm);

            SetProperty("partition." + partition + ".verified.root_digest",

                        hashtree_info->root_digest);

        }

    }