image_types_phosphor.bbclass: Add a mmc-verity image type

Add support to create a rootfs image setup with dm-verity
which allows for secure boot of a BMC’s userspace.

This image type can be enabled by adding 'IMAGE_FSTYPES = "mmc-verity"'
to a machine's conf file.

Tested: Booted an image on QEMU.

(From meta-phosphor rev: 86cfbd54a3ef9c7379e044723253a38f850bab56)

Change-Id: If866a71cb031abfef6b1ab3c5ebe0869b1595300
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Adriana Kobylak <anoo@us.ibm.com>
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>

1 files changed, 99 insertions, 2 deletions

diff --git a/meta-phosphor/classes/image_types_phosphor.bbclass b/meta-phosphor/classes/image_types_phosphor.bbclass
index e29f4ff47..10388d257 100644
--- a/meta-phosphor/classes/image_types_phosphor.bbclass
+++ b/meta-phosphor/classes/image_types_phosphor.bbclass
@@ -19,15 +19,19 @@ FLASH_UBI_OVERLAY_BASETYPE ?= "ubifs"
 FLASH_EXT4_BASETYPE ?= "ext4"
 FLASH_EXT4_OVERLAY_BASETYPE ?= "ext4"
 
-IMAGE_TYPES += "mtd-static mtd-static-alltar mtd-static-tar mtd-ubi mtd-ubi-tar mmc-ext4-tar"
+IMAGE_TYPES += "mtd-static mtd-static-alltar mtd-static-tar mtd-ubi mtd-ubi-tar mmc-verity mmc-ext4-tar"
 
 IMAGE_TYPEDEP_mtd-static = "${IMAGE_BASETYPE}"
 IMAGE_TYPEDEP_mtd-static-tar = "${IMAGE_BASETYPE}"
 IMAGE_TYPEDEP_mtd-static-alltar = "mtd-static"
 IMAGE_TYPEDEP_mtd-ubi = "${FLASH_UBI_BASETYPE}"
 IMAGE_TYPEDEP_mtd-ubi-tar = "${FLASH_UBI_BASETYPE}"
+IMAGE_TYPEDEP_mmc-verity = "${FLASH_EXT4_BASETYPE}"
 IMAGE_TYPEDEP_mmc-ext4-tar = "${FLASH_EXT4_BASETYPE}"
-IMAGE_TYPES_MASKED += "mtd-static mtd-static-alltar mtd-static-tar mtd-ubi mtd-ubi-tar mmc-ext4-tar"
+IMAGE_TYPES_MASKED += "mtd-static mtd-static-alltar mtd-static-tar mtd-ubi mtd-ubi-tar mmc-verity mmc-ext4-tar"
+
+IMAGE_BLOCK_SIZE ?= "4096"
+EXTRA_IMAGECMD_ext4 = "-b ${IMAGE_BLOCK_SIZE}"
 
 # Flash characteristics in KB unless otherwise noted
 DISTROOVERRIDES .= ":flash-${FLASH_SIZE}"
@@ -216,6 +220,95 @@ do_make_ubi[depends] += " \
         mtd-utils-native:do_populate_sysroot \
         "
 
+python do_generate_mmc_verity() {
+    import os
+    import subprocess
+
+    rootfs_image = os.path.join(d.getVar('IMGDEPLOYDIR', True),
+                                '%s.%s' % (
+                                    d.getVar('IMAGE_LINK_NAME', True),
+                                    d.getVar('FLASH_EXT4_BASETYPE', True)))
+
+    verity_image = 'verity-%s.%s' % (
+                            d.getVar('IMAGE_LINK_NAME', True),
+                            d.getVar('FLASH_EXT4_BASETYPE', True))
+
+    subprocess.check_call(['dd',
+                           'if=%s' % rootfs_image,
+                           'of=%s' % verity_image])
+
+    # dm-verity values
+    sector_size = 512
+    block_size = int(d.getVar('IMAGE_BLOCK_SIZE', True))
+    verity_algo = "sha256"
+    rootfs_image_size = os.stat(rootfs_image).st_size
+
+    def align_up(number, boundary):
+        return ((number + (boundary - 1)) // boundary) * boundary
+
+    # verity metadata must be aligned on the block boundary subsequent to the
+    # end of the data
+    verity_hash_offset = align_up(rootfs_image_size, block_size)
+
+    verity_hash_blocks = verity_hash_offset // block_size
+
+    # the output of 'veritysetup format' looks like:
+    # VERITY header information for obmc-phosphor-image-witherspoon.squashfs-xz
+    # UUID:                269b5934-de5b-45b0-99a3-56b219a7b544
+    # Hash type:           1
+    # Data blocks:         4523
+    # Data block size:     4096
+    # Hash block size:     4096
+    # Hash algorithm:      sha256
+    # Salt:                8fca9eff342fc0cf2964057257ea80813a223cb2e540a38458142edeb190e12e
+    # Root hash:           38ef00d23fa89300dcf66e7494d25246d03bf846b4119b34e7b1587c0b6fe1d9
+    verity_hash_file = "verity-hash-verification-data"
+    with open(verity_hash_file, 'w') as f:
+       subprocess.check_call(['veritysetup',
+                              'format',
+                              '--hash=%s'% verity_algo,
+                              '--data-block-size=%i' % block_size,
+                              '--hash-block-size=%i' % block_size,
+                              '--hash-offset=%i' % verity_hash_offset,
+                              '%s' % verity_image,
+                              '%s' % verity_image], stdout=f, stderr=f)
+
+    for line in open(verity_hash_file, "r"):
+        if "Salt" in line:
+            verity_salt = line.split()[-1]
+        if "Root" in line:
+            verity_root = line.split()[-1]
+
+    verity_image_size = os.stat(verity_image).st_size
+
+    # Make an appropriately sized image for MMC
+    mmc_image_name = "%s.mmc" % d.getVar('IMAGE_NAME', True)
+    mmc_image_path = os.path.join(d.getVar('IMGDEPLOYDIR', True),
+                                    '%s' % mmc_image_name)
+
+    # CSD size accommodates MMC limitations that are relevant to QEMU
+    csd_size = (1 << (9 + 9 - 1 + 2))
+
+    with open(mmc_image_path, 'w') as fd:
+        os.posix_fallocate(fd.fileno(), 0, align_up(verity_image_size, csd_size))
+    subprocess.check_call(['dd',
+                           'if=%s' % verity_image,
+                           'of=%s' % mmc_image_path,
+                           'conv=notrunc'])
+
+    os.chdir("%s" % d.getVar('IMGDEPLOYDIR', True))
+    mmc_link_name = os.path.join(d.getVar('IMGDEPLOYDIR', True),
+                                '%s.mmc' % d.getVar('IMAGE_LINK_NAME', True))
+    if os.path.lexists(mmc_link_name):
+        os.remove(mmc_link_name)
+    os.symlink(mmc_image_name, mmc_link_name)
+}
+do_generate_mmc_verity[dirs] = "${S}/mmc"
+do_generate_mmc_verity[depends] += " \
+    ${PN}:do_image_${FLASH_EXT4_BASETYPE} \
+    cryptsetup-native:do_populate_sysroot \
+    "
+
 do_mk_static_nor_image() {
 	# Assemble the flash image
 	mk_empty_image ${IMGDEPLOYDIR}/${IMAGE_NAME}.static.mtd ${FLASH_SIZE}
@@ -483,6 +576,10 @@ python() {
                 'do_image_complete',
                 'do_generate_rwfs_ubi do_generate_phosphor_manifest', d)
 
+    if 'mmc-verity' in types:
+        bb.build.addtask(
+                'do_generate_mmc_verity',
+                'do_image_complete','', d)
     if 'mmc-ext4-tar' in types:
         bb.build.addtask(
                 'do_generate_ext4_tar',