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Commit 4bdf83e1 authored by David Anderson's avatar David Anderson Committed by Automerger Merge Worker
Browse files

Merge "snapuserd: Restrict where reads/writes to dm_user_header happen." into main am: 80afdc08 

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2633930



Change-Id: Ib093314db4a768d500804fdfc68ff06b76985750
Signed-off-by: default avatarAutomerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
parents 5d00d08c 80afdc08

fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_core.h

+0 −1
Original line number Diff line number Diff line
@@ -119,7 +119,6 @@ class Worker { 
    }



    // Functions interacting with dm-user

    bool ReadDmUserHeader();

    bool WriteDmUserPayload(size_t size);

    bool DmuserReadRequest();

fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_dm_user.cpp

+34 −50
Original line number Diff line number Diff line
@@ -290,21 +290,6 @@ bool Worker::RunThread() { 
    return true;

}



// Read Header from dm-user misc device. This gives

// us the sector number for which IO is issued by dm-snapshot device

bool Worker::ReadDmUserHeader() {

    if (!android::base::ReadFully(ctrl_fd_, bufsink_.GetBufPtr(), sizeof(struct dm_user_header))) {

        if (errno != ENOTBLK) {

            SNAP_PLOG(ERROR) << "Control-read failed";

        }



        SNAP_PLOG(DEBUG) << "ReadDmUserHeader failed....";

        return false;

    }



    return true;

}



// Send the payload/data back to dm-user misc device.

bool Worker::WriteDmUserPayload(size_t size) {

    size_t payload_size = size;
@@ -345,19 +330,15 @@ bool Worker::ReadDataFromBaseDevice(sector_t sector, size_t read_size) { 
}



bool Worker::ReadAlignedSector(sector_t sector, size_t sz) {

    struct dm_user_header* header = bufsink_.GetHeaderPtr();

    size_t remaining_size = sz;

    std::vector<std::pair<sector_t, const CowOperation*>>& chunk_vec = snapuserd_->GetChunkVec();

    bool io_error = false;

    int ret = 0;



    do {

        // Process 1MB payload at a time

        size_t read_size = std::min(PAYLOAD_BUFFER_SZ, remaining_size);



        header->type = DM_USER_RESP_SUCCESS;

        size_t total_bytes_read = 0;

        io_error = false;

        bufsink_.ResetBufferOffset();



        while (read_size) {
@@ -375,7 +356,7 @@ bool Worker::ReadAlignedSector(sector_t sector, size_t sz) { 
                // device.

                if (!ReadDataFromBaseDevice(sector, size)) {

                    SNAP_LOG(ERROR) << "ReadDataFromBaseDevice failed";

                    header->type = DM_USER_RESP_ERROR;

                    return false;

                }



                ret = size;
@@ -384,26 +365,18 @@ bool Worker::ReadAlignedSector(sector_t sector, size_t sz) { 
                // process it.

                if (!ProcessCowOp(it->second)) {

                    SNAP_LOG(ERROR) << "ProcessCowOp failed";

                    header->type = DM_USER_RESP_ERROR;

                    return false;

                }



                ret = BLOCK_SZ;

            }



            // Just return the header if it is an error

            if (header->type == DM_USER_RESP_ERROR) {

                RespondIOError();

                io_error = true;

                break;

            }



            read_size -= ret;

            total_bytes_read += ret;

            sector += (ret >> SECTOR_SHIFT);

            bufsink_.UpdateBufferOffset(ret);

        }



        if (!io_error) {

        if (!WriteDmUserPayload(total_bytes_read)) {

            return false;

        }
@@ -411,8 +384,7 @@ bool Worker::ReadAlignedSector(sector_t sector, size_t sz) { 
        SNAP_LOG(DEBUG) << "WriteDmUserPayload success total_bytes_read: " << total_bytes_read

                        << " remaining_size: " << remaining_size;

        remaining_size -= total_bytes_read;

        }

    } while (remaining_size > 0 && !io_error);

    } while (remaining_size > 0);



    return true;

}
@@ -453,8 +425,6 @@ int Worker::ReadUnalignedSector( 
}



bool Worker::ReadUnalignedSector(sector_t sector, size_t size) {

    struct dm_user_header* header = bufsink_.GetHeaderPtr();

    header->type = DM_USER_RESP_SUCCESS;

    bufsink_.ResetBufferOffset();

    std::vector<std::pair<sector_t, const CowOperation*>>& chunk_vec = snapuserd_->GetChunkVec();
@@ -622,9 +592,15 @@ bool Worker::DmuserReadRequest() { 
}



bool Worker::ProcessIORequest() {

    // Read Header from dm-user misc device. This gives

    // us the sector number for which IO is issued by dm-snapshot device

    struct dm_user_header* header = bufsink_.GetHeaderPtr();

    if (!android::base::ReadFully(ctrl_fd_, header, sizeof(*header))) {

        if (errno != ENOTBLK) {

            SNAP_PLOG(ERROR) << "Control-read failed";

        }



    if (!ReadDmUserHeader()) {

        SNAP_PLOG(DEBUG) << "ReadDmUserHeader failed....";

        return false;

    }
@@ -634,26 +610,34 @@ bool Worker::ProcessIORequest() { 
    SNAP_LOG(DEBUG) << "Daemon: msg->type: " << std::dec << header->type;

    SNAP_LOG(DEBUG) << "Daemon: msg->flags: " << std::dec << header->flags;



    // Use the same header buffer as the response header.

    int request_type = header->type;

    header->type = DM_USER_RESP_SUCCESS;

    header_response_ = true;



    switch (header->type) {

        case DM_USER_REQ_MAP_READ: {

            if (!DmuserReadRequest()) {

                return false;

            }

    bool ok;

    switch (request_type) {

        case DM_USER_REQ_MAP_READ:

            ok = DmuserReadRequest();

            break;

        }



        case DM_USER_REQ_MAP_WRITE: {

        case DM_USER_REQ_MAP_WRITE:

            // TODO: We should not get any write request

            // to dm-user as we mount all partitions

            // as read-only. Need to verify how are TRIM commands

            // handled during mount.

            return false;

        }

            ok = false;

            break;



        default:

            ok = false;

            break;

    }



    return true;

    if (!ok && header->type != DM_USER_RESP_ERROR) {

        RespondIOError();

    }

    return ok;

}



}  // namespace snapshot