diff options
| -rw-r--r-- | Kconfig | 10 | ||||
| -rw-r--r-- | common/image-sig.c | 5 | ||||
| -rw-r--r-- | test/py/tests/test_vboot.py | 33 | ||||
| -rw-r--r-- | tools/Makefile | 1 |
4 files changed, 49 insertions, 0 deletions
@@ -267,6 +267,16 @@ config FIT_SIGNATURE format support in this case, enable it using CONFIG_IMAGE_FORMAT_LEGACY. +config FIT_SIGNATURE_MAX_SIZE + hex "Max size of signed FIT structures" + depends on FIT_SIGNATURE + default 0x10000000 + help + This option sets a max size in bytes for verified FIT uImages. + A sane value of 256MB protects corrupted DTB structures from overlapping + device memory. Assure this size does not extend past expected storage + space. + config FIT_VERBOSE bool "Show verbose messages when FIT images fail" help diff --git a/common/image-sig.c b/common/image-sig.c index f65d883994..8d2fd10db6 100644 --- a/common/image-sig.c +++ b/common/image-sig.c @@ -156,6 +156,11 @@ static int fit_image_setup_verify(struct image_sign_info *info, { char *algo_name; + if (fdt_totalsize(fit) > CONFIG_FIT_SIGNATURE_MAX_SIZE) { + *err_msgp = "Total size too large"; + return 1; + } + if (fit_image_hash_get_algo(fit, noffset, &algo_name)) { *err_msgp = "Can't get hash algo property"; return -1; diff --git a/test/py/tests/test_vboot.py b/test/py/tests/test_vboot.py index ee939f2034..3d25ec3d66 100644 --- a/test/py/tests/test_vboot.py +++ b/test/py/tests/test_vboot.py @@ -26,6 +26,7 @@ Tests run with both SHA1 and SHA256 hashing. import pytest import sys +import struct import u_boot_utils as util @pytest.mark.boardspec('sandbox') @@ -105,6 +106,26 @@ def test_vboot(u_boot_console): util.run_and_log(cons, [mkimage, '-F', '-k', tmpdir, '-K', dtb, '-r', fit]) + def replace_fit_totalsize(size): + """Replace FIT header's totalsize with something greater. + + The totalsize must be less than or equal to FIT_SIGNATURE_MAX_SIZE. + If the size is greater, the signature verification should return false. + + Args: + size: The new totalsize of the header + + Returns: + prev_size: The previous totalsize read from the header + """ + total_size = 0 + with open(fit, 'r+b') as handle: + handle.seek(4) + total_size = handle.read(4) + handle.seek(4) + handle.write(struct.pack(">I", size)) + return struct.unpack(">I", total_size)[0] + def test_with_algo(sha_algo): """Test verified boot with the given hash algorithm. @@ -146,6 +167,18 @@ def test_vboot(u_boot_console): util.run_and_log(cons, [fit_check_sign, '-f', fit, '-k', tmpdir, '-k', dtb]) + # Replace header bytes + bcfg = u_boot_console.config.buildconfig + max_size = int(bcfg.get('config_fit_signature_max_size', 0x10000000), 0) + existing_size = replace_fit_totalsize(max_size + 1) + run_bootm(sha_algo, 'Signed config with bad hash', 'Bad Data Hash', False) + cons.log.action('%s: Check overflowed FIT header totalsize' % sha_algo) + + # Replace with existing header bytes + replace_fit_totalsize(existing_size) + run_bootm(sha_algo, 'signed config', 'dev+', True) + cons.log.action('%s: Check default FIT header totalsize' % sha_algo) + # Increment the first byte of the signature, which should cause failure sig = util.run_and_log(cons, 'fdtget -t bx %s %s value' % (fit, sig_node)) diff --git a/tools/Makefile b/tools/Makefile index 5dd33ed4d5..0c3341e695 100644 --- a/tools/Makefile +++ b/tools/Makefile @@ -133,6 +133,7 @@ ifdef CONFIG_FIT_SIGNATURE # This affects include/image.h, but including the board config file # is tricky, so manually define this options here. HOST_EXTRACFLAGS += -DCONFIG_FIT_SIGNATURE +HOST_EXTRACFLAGS += -DCONFIG_FIT_SIGNATURE_MAX_SIZE=$(CONFIG_FIT_SIGNATURE_MAX_SIZE) endif ifdef CONFIG_SYS_U_BOOT_OFFS |