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Commit b6ea435a authored by David Zeuthen's avatar David Zeuthen
Browse files

fastboot: Add --disable-verity and --disable-verification options. 

This can be used to disable verity and/or verification when flashing a
build to a device. It works with both 'fastboot flashall' and
'fastboot flash vbmeta /path/to/vbmeta.img'.

Bug: 62903976
Test: Manually tested.
Change-Id: Iad22d42a9dd5befd70ecd0224803721a10a28d90
parent 69ff5009

fastboot/fastboot.cpp

+58 −0
Original line number Diff line number Diff line
@@ -93,6 +93,9 @@ static unsigned ramdisk_offset = 0x01000000; 
static unsigned second_offset  = 0x00f00000;

static unsigned tags_offset    = 0x00000100;



static bool g_disable_verity = false;

static bool g_disable_verification = false;



static const std::string convert_fbe_marker_filename("convert_fbe");



enum fb_buffer_type {
@@ -419,6 +422,10 @@ static int show_help() { 
            "  --skip-reboot                            Will not reboot the device when\n"

            "                                           performing commands that normally\n"

            "                                           trigger a reboot.\n"

            "  --disable-verity                         Set the disable-verity flag in the\n"

            "                                           the vbmeta image being flashed.\n"

            "  --disable-verification                   Set the disable-verification flag in"

            "                                           the vbmeta image being flashed.\n"

#if !defined(_WIN32)

            "  --wipe-and-use-fbe                       On devices which support it,\n"

            "                                           erase userdata and cache, and\n"
@@ -858,10 +865,55 @@ static bool load_buf(Transport* transport, const char* fname, struct fastboot_bu 
    return load_buf_fd(transport, fd.release(), buf);

}



static void rewrite_vbmeta_buffer(struct fastboot_buffer* buf) {

    // Buffer needs to be at least the size of the VBMeta struct which

    // is 256 bytes.

    if (buf->sz < 256) {

        return;

    }



    int fd = make_temporary_fd();

    if (fd == -1) {

        die("Failed to create temporary file for vbmeta rewriting");

    }



    std::string data;

    if (!android::base::ReadFdToString(buf->fd, &data)) {

        die("Failed reading from vbmeta");

    }



    // There's a 32-bit big endian |flags| field at offset 120 where

    // bit 0 corresponds to disable-verity and bit 1 corresponds to

    // disable-verification.

    //

    // See external/avb/libavb/avb_vbmeta_image.h for the layout of

    // the VBMeta struct.

    if (g_disable_verity) {

        data[123] |= 0x01;

    }

    if (g_disable_verification) {

        data[123] |= 0x02;

    }



    if (!android::base::WriteStringToFd(data, fd)) {

        die("Failed writing to modified vbmeta");

    }

    close(buf->fd);

    buf->fd = fd;

    lseek(fd, 0, SEEK_SET);

}



static void flash_buf(const char *pname, struct fastboot_buffer *buf)

{

    sparse_file** s;



    // Rewrite vbmeta if that's what we're flashing and modification has been requested.

    if ((g_disable_verity || g_disable_verification) &&

        (strcmp(pname, "vbmeta") == 0 || strcmp(pname, "vbmeta_a") == 0 ||

         strcmp(pname, "vbmeta_b") == 0)) {

        rewrite_vbmeta_buffer(buf);

    }



    switch (buf->type) {

        case FB_BUFFER_SPARSE: {

            std::vector<std::pair<sparse_file*, int64_t>> sparse_files;
@@ -1470,6 +1522,8 @@ int main(int argc, char **argv) 
        {"set-active", optional_argument, 0, 'a'},

        {"skip-secondary", no_argument, 0, 0},

        {"skip-reboot", no_argument, 0, 0},

        {"disable-verity", no_argument, 0, 0},

        {"disable-verification", no_argument, 0, 0},

#if !defined(_WIN32)

        {"wipe-and-use-fbe", no_argument, 0, 0},

#endif
@@ -1555,6 +1609,10 @@ int main(int argc, char **argv) 
                skip_secondary = true;

            } else if (strcmp("skip-reboot", longopts[longindex].name) == 0 ) {

                skip_reboot = true;

            } else if (strcmp("disable-verity", longopts[longindex].name) == 0 ) {

                g_disable_verity = true;

            } else if (strcmp("disable-verification", longopts[longindex].name) == 0 ) {

                g_disable_verification = true;

#if !defined(_WIN32)

            } else if (strcmp("wipe-and-use-fbe", longopts[longindex].name) == 0) {

                wants_wipe = true;