Currently Verified Boot fails if there is a signature verification failure using required key in U-boot DTB. This patch adds support for multiple required keys. This means if verified boot passes with one of the required keys, u-boot will continue the OS hand off.

There was a prior attempt to resolve this with the following patch: https://lists.denx.de/pipermail/u-boot/2019-April/366047.html The above patch was failing "make tests".

Signed-off-by: Thirupathaiah Annapureddy thiruan@linux.microsoft.com --- common/image-fit-sig.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/common/image-fit-sig.c b/common/image-fit-sig.c index cc1967109e..4d25d4c541 100644 --- a/common/image-fit-sig.c +++ b/common/image-fit-sig.c @@ -416,6 +416,8 @@ int fit_config_verify_required_sigs(const void *fit, int conf_noffset, { int noffset; int sig_node; + int verified = 0; + int reqd_sigs = 0;

/* Work out what we need to verify */ sig_node = fdt_subnode_offset(sig_blob, 0, FIT_SIG_NODENAME); @@ -433,15 +435,23 @@ int fit_config_verify_required_sigs(const void *fit, int conf_noffset, NULL); if (!required || strcmp(required, "conf")) continue; + + reqd_sigs++; + ret = fit_config_verify_sig(fit, conf_noffset, sig_blob, noffset); if (ret) { printf("Failed to verify required signature '%s'\n", fit_get_name(sig_blob, noffset, NULL)); - return ret; + } else { + verified = 1; + break; } }

+ if (reqd_sigs && !verified) + return -EPERM; + return 0; }

Add a test to verify the support for multiple required keys. This patch also fixes existing test where dev key is assumed to be marked as not required, although it is marked as required.

Note that this patch re-added sign_fit_norequire(). sign_fit_norequire() was removed as part of the following: commit b008677daf2a ("test: vboot: Fix pylint errors"). This patch leverages sign_fit_norequire() to fix the existing bug.

Signed-off-by: Thirupathaiah Annapureddy thiruan@linux.microsoft.com --- test/py/tests/test_vboot.py | 33 +++++++++++++++++++++++++++++++-- 1 file changed, 31 insertions(+), 2 deletions(-)

diff --git a/test/py/tests/test_vboot.py b/test/py/tests/test_vboot.py index 6b998cfd70..9773ee3509 100644 --- a/test/py/tests/test_vboot.py +++ b/test/py/tests/test_vboot.py @@ -126,6 +126,23 @@ def test_vboot(u_boot_console, sha_algo, padding, sign_options, required): cons.log.action('%s: Sign images' % sha_algo) util.run_and_log(cons, args)

+ def sign_fit_norequire(sha_algo, options): + """Sign the FIT + + Signs the FIT and writes the signature into it. It also writes the + public key into the dtb. It does not mark key as 'required' in dtb. + + Args: + sha_algo: Either 'sha1' or 'sha256', to select the algorithm to + use. + options: Options to provide to mkimage. + """ + args = [mkimage, '-F', '-k', tmpdir, '-K', dtb, fit] + if options: + args += options.split(' ') + cons.log.action('%s: Sign images' % sha_algo) + util.run_and_log(cons, args) + def replace_fit_totalsize(size): """Replace FIT header's totalsize with something greater.

@@ -279,15 +296,27 @@ def test_vboot(u_boot_console, sha_algo, padding, sign_options, required): # Build the FIT with dev key (keys NOT required). This adds the # signature into sandbox-u-boot.dtb, NOT marked 'required'. make_fit('sign-configs-%s%s.its' % (sha_algo, padding)) - sign_fit(sha_algo, sign_options) + sign_fit_norequire(sha_algo, sign_options)

# So now sandbox-u-boot.dtb two signatures, for the prod and dev keys. # Only the prod key is set as 'required'. But FIT we just built has - # a dev signature only (sign_fit() overwrites the FIT). + # a dev signature only (sign_fit_norequire() overwrites the FIT). # Try to boot the FIT with dev key. This FIT should not be accepted by # U-Boot because the prod key is required. run_bootm(sha_algo, 'required key', '', False)

+ # Build the FIT with dev key (keys required) and sign it. This puts the + # signature into sandbox-u-boot.dtb, marked 'required'. + make_fit('sign-configs-%s%s.its' % (sha_algo, padding)) + sign_fit(sha_algo, sign_options) + + # So now sandbox-u-boot.dtb two signatures, for the prod and dev keys. + # Both the dev and prod key are set as 'required'. But FIT we just built has + # a dev signature only (sign_fit() overwrites the FIT). + # Try to boot the FIT with dev key. This FIT should be accepted by + # U-Boot because the dev key is required. + run_bootm(sha_algo, 'multi required key', '', True) + cons = u_boot_console tmpdir = cons.config.result_dir + '/' datadir = cons.config.source_dir + '/test/py/tests/vboot/'