doc/README.ti-secure

   1 README on how boot images are created for secure TI devices
   2
   3 CONFIG_TI_SECURE_DEVICE:
   4 Secure TI devices require a boot image that is authenticated by ROM
   5 code to function. Without this, even JTAG remains locked and the
   6 device is essentially useless. In order to create a valid boot image for
   7 a secure device from TI, the initial public software image must be signed
   8 and combined with various headers, certificates, and other binary images.
   9
  10 Information on the details on the complete boot image format can be obtained
  11 from Texas Instruments. The tools used to generate boot images for secure
  12 devices are part of a secure development package (SECDEV) that can be
  13 downloaded from:
  14
  15         http://www.ti.com/mysecuresoftware (login required)
  16
  17 The secure development package is access controlled due to NDA and export
  18 control restrictions. Access must be requested and granted by TI before the
  19 package is viewable and downloadable. Contact TI, either online or by way
  20 of a local TI representative, to request access.
  21
  22 Booting of U-Boot SPL
  23 =====================
  24
  25         When CONFIG_TI_SECURE_DEVICE is set, the U-Boot SPL build process
  26         requires the presence and use of these tools in order to create a
  27         viable boot image. The build process will look for the environment
  28         variable TI_SECURE_DEV_PKG, which should be the path of the installed
  29         SECDEV package. If the TI_SECURE_DEV_PKG variable is not defined or
  30         if it is defined but doesn't point to a valid SECDEV package, a
  31         warning is issued during the build to indicate that a final secure
  32         bootable image was not created.
  33
  34         Within the SECDEV package exists an image creation script:
  35
  36         ${TI_SECURE_DEV_PKG}/scripts/create-boot-image.sh
  37
  38         This is called as part of the SPL/u-boot build process. As the secure
  39         boot image formats and requirements differ between secure SOC from TI,
  40         the purpose of this script is to abstract these details as much as
  41         possible.
  42
  43         The script is basically the only required interface to the TI SECDEV
  44         package for creating a bootable SPL image for secure TI devices.
  45
  46         Invoking the script for AM33xx Secure Devices
  47         =============================================
  48
  49         create-boot-image.sh \
  50                 <IMAGE_FLAG> <INPUT_FILE> <OUTPUT_FILE> <SPL_LOAD_ADDR>
  51
  52         <IMAGE_FLAG> is a value that specifies the type of the image to
  53         generate OR the action the image generation tool will take. Valid
  54         values are:
  55                 SPI_X-LOADER - Generates an image for SPI flash (byte swapped)
  56                 X-LOADER - Generates an image for non-XIP flash
  57                 MLO - Generates an image for SD/MMC/eMMC media
  58                 2ND - Generates an image for USB, UART and Ethernet
  59                 XIP_X-LOADER - Generates a single stage u-boot for NOR/QSPI XiP
  60
  61         <INPUT_FILE> is the full path and filename of the public world boot
  62         loaderbinary file (depending on the boot media, this is usually
  63         either u-boot-spl.bin or u-boot.bin).
  64
  65         <OUTPUT_FILE> is the full path and filename of the final secure
  66         image. The output binary images should be used in place of the standard
  67         non-secure binary images (see the platform-specific user's guides and
  68         releases notes for how the non-secure images are typically used)
  69         u-boot-spl_HS_SPI_X-LOADER - byte swapped boot image for SPI flash
  70         u-boot-spl_HS_X-LOADER - boot image for NAND or SD/MMC/eMMC rawmode
  71         u-boot-spl_HS_MLO - boot image for SD/MMC/eMMC media
  72         u-boot-spl_HS_2ND - boot image for USB, UART and Ethernet
  73         u-boot_HS_XIP_X-LOADER - boot image for NOR or QSPI Xip flash
  74
  75         <SPL_LOAD_ADDR> is the address at which SOC ROM should load the
  76         <INPUT_FILE>
  77
  78         Invoking the script for AM43xx Secure Devices
  79         =============================================
  80
  81         create-boot-image.sh \
  82                 <IMAGE_FLAG> <INPUT_FILE> <OUTPUT_FILE> <SPL_LOAD_ADDR>
  83
  84         <IMAGE_FLAG> is a value that specifies the type of the image to
  85         generate OR the action the image generation tool will take. Valid
  86         values are:
  87                 SPI_X-LOADER - Generates an image for SPI flash (byte
  88                         swapped)
  89                 XIP_X-LOADER - Generates a single stage u-boot for
  90                         NOR/QSPI XiP
  91                 ISSW - Generates an image for all other boot modes
  92
  93         <INPUT_FILE> is the full path and filename of the public world boot
  94         loaderbinary file (depending on the boot media, this is usually
  95         either u-boot-spl.bin or u-boot.bin).
  96
  97         <OUTPUT_FILE> is the full path and filename of the final secure
  98         image. The output binary images should be used in place of the standard
  99         non-secure binary images (see the platform-specific user's guides and
 100         releases notes for how the non-secure images are typically used)
 101         u-boot-spl_HS_SPI_X-LOADER - byte swapped boot image for SPI flash
 102         u-boot_HS_XIP_X-LOADER - boot image for NOR or QSPI flash
 103         u-boot-spl_HS_ISSW - boot image for all other boot media
 104
 105         <SPL_LOAD_ADDR> is the address at which SOC ROM should load the
 106         <INPUT_FILE>
 107
 108         Invoking the script for DRA7xx/AM57xx Secure Devices
 109         ====================================================
 110
 111         create-boot-image.sh <IMAGE_TYPE> <INPUT_FILE> <OUTPUT_FILE>
 112
 113         <IMAGE_TYPE> is a value that specifies the type of the image to
 114         generate OR the action the image generation tool will take. Valid
 115         values are:
 116                 X-LOADER - Generates an image for NOR or QSPI boot modes
 117                 MLO - Generates an image for SD/MMC/eMMC boot modes
 118                 ULO - Generates an image for USB/UART peripheral boot modes
 119                 Note: ULO is not yet used by the u-boot build process
 120
 121         <INPUT_FILE> is the full path and filename of the public world boot
 122         loader binary file (for this platform, this is always u-boot-spl.bin).
 123
 124         <OUTPUT_FILE> is the full path and filename of the final secure image.
 125         The output binary images should be used in place of the standard
 126         non-secure binary images (see the platform-specific user's guides
 127         and releases notes for how the non-secure images are typically used)
 128         u-boot-spl_HS_MLO - boot image for SD/MMC/eMMC. This image is
 129                 copied to a file named MLO, which is the name that
 130                 the device ROM bootloader requires for loading from
 131                 the FAT partition of an SD card (same as on
 132                 non-secure devices)
 133         u-boot-spl_HS_X-LOADER - boot image for all other flash memories
 134                 including QSPI and NOR flash
 135
 136         Invoking the script for Keystone2 Secure Devices
 137         =============================================
 138
 139         create-boot-image.sh \
 140                 <UNUSED> <INPUT_FILE> <OUTPUT_FILE> <UNUSED>
 141
 142         <UNUSED> is currently ignored and reserved for future use.
 143
 144         <INPUT_FILE> is the full path and filename of the public world boot
 145         loader binary file (only u-boot.bin is currently supported on
 146         Keystone2 devices, u-boot-spl.bin is not currently supported).
 147
 148         <OUTPUT_FILE> is the full path and filename of the final secure image.
 149         The output binary images should be used in place of the standard
 150         non-secure binary images (see the platform-specific user's guides
 151         and releases notes for how the non-secure images are typically used)
 152         u-boot_HS_MLO - signed and encrypted boot image that can be used to
 153                 boot from all media. Secure boot from SPI NOR flash is not
 154                 currently supported.
 155
 156 Booting of Primary U-Boot (u-boot.img)
 157 ======================================
 158
 159         The SPL image is responsible for loading the next stage boot loader,
 160         which is the main u-boot image. For secure TI devices, the SPL will
 161         be authenticated, as described above, as part of the particular
 162         device's ROM boot process. In order to continue the secure boot
 163         process, the authenticated SPL must authenticate the main u-boot
 164         image that it loads.
 165
 166         The configurations for secure TI platforms are written to make the boot
 167         process use the FIT image format for the u-boot.img (CONFIG_SPL_FRAMEWORK
 168         and CONFIG_SPL_LOAD_FIT). With these configurations the binary
 169         components that the SPL loads include a specific DTB image and u-boot
 170         image. These DTB image may be one of many available to the boot
 171         process. In order to secure these components so that they can be
 172         authenticated by the SPL as they are loaded from the FIT image, the
 173         build procedure for secure TI devices will secure these images before
 174         they are integrated into the FIT image. When those images are extracted
 175         from the FIT image at boot time, they are post-processed to verify that
 176         they are still secure. The outlined security-related SPL post-processing
 177         is enabled through the CONFIG_SPL_FIT_IMAGE_POST_PROCESS option which
 178         must be enabled for the secure boot scheme to work. In order to allow
 179         verifying proper operation of the secure boot chain in case of successful
 180         authentication messages like "Authentication passed: CERT_U-BOOT-NOD" are
 181         output by the SPL to the console for each blob that got extracted from the
 182         FIT image. Note that the last part of this log message is the (truncated)
 183         name of the signing certificate embedded into the blob that got processed.
 184
 185         The exact details of the how the images are secured is handled by the
 186         SECDEV package. Within the SECDEV package exists a script to process
 187         an input binary image:
 188
 189         ${TI_SECURE_DEV_PKG}/scripts/secure-binary-image.sh
 190
 191         This is called as part of the u-boot build process. As the secure
 192         image formats and requirements can differ between the various secure
 193         SOCs from TI, this script in the SECDEV package abstracts these
 194         details. This script is essentially the only required interface to the
 195         TI SECDEV package for creating a u-boot.img image for secure TI
 196         devices.
 197
 198         The SPL/u-boot code contains calls to dedicated secure ROM functions
 199         to perform the validation on the secured images. The details of the
 200         interface to those functions is shown in the code. The summary
 201         is that they are accessed by invoking an ARM secure monitor call to
 202         the device's secure ROM (fixed read-only-memory that is secure and
 203         only accessible when the ARM core is operating in the secure mode).
 204
 205         Invoking the secure-binary-image script for Secure Devices
 206         ==========================================================
 207
 208         secure-binary-image.sh <INPUT_FILE> <OUTPUT_FILE>
 209
 210         <INPUT_FILE> is the full path and filename of the input binary image
 211
 212         <OUTPUT_FILE> is the full path and filename of the output secure image.