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vboot: Use kernel max rollforward NV storage field

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Kernel verification will now roll forward the minimum allowable
version in the TPM no farther than the kernel_max_rollforward setting.

Note that CL:765573 changes chromeos-setgoodkernel so it always sets
kernel_max_rollforward to 0xfffffffe when marking a kernel as good.
That ensures that firmware with this setting will behave the same for
now as existing firmware.

BUG=chromium:783997
BRANCH=none
CQ-DEPEND=CL:765573
TEST=make runtests
     Manual testing:
     crossystem tpm_kernvel --> print current kernel version in TPM
     - Resign the kernel with a higher version
     - Reboot
     - Wait a minute for chromeos-setgoodkernel to run
     crossystem kernel_max_rollforward=0
     - Reboot
     crossystem tpm_kernvel --> has not changed
     - Wait a minute for chromeos-setgoodkernel to run
     crossystem kernel_max_rollforward -> 0xfffffffe
     - Reboot
     crossystem tpm_kernvel --> has changed to the higher version

Change-Id: Ia32ecb7fa4078548cd311541ccbe120570cf1bc5
Reviewed-on: https://chromium-review.googlesource.com/765574
Commit-Ready: Randall Spangler <rspangler@chromium.org>
Tested-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Stefan Reinauer <reinauer@google.com>
This commit is contained in:
Randall Spangler
2017-10-30 15:28:53 -07:00
committed by chrome-bot
parent 4aaaeca130
commit 17fb34b647
2 changed files with 36 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

20
firmware/lib/vboot_api_kernel.c
View File

@@ -188,6 +188,7 @@ VbError_t VbBootNormal(struct vb2_context *ctx, VbCommonParams *cparams)
{
VbSharedDataHeader *shared =
(VbSharedDataHeader *)cparams->shared_data_blob;
uint32_t max_rollforward;
/* Boot from fixed disk only */
VB2_DEBUG("Entering\n");
@@ -224,6 +225,25 @@ VbError_t VbBootNormal(struct vb2_context *ctx, VbCommonParams *cparams)
return rv;
}
/* Limit kernel version rollforward if needed */
if (0 == VbNvGet(&vnc, VBNV_KERNEL_MAX_ROLLFORWARD, &max_rollforward)) {
/*
* Can't limit kernel version to less than the version
* currently in the TPM. That is, we're limiting rollforward,
* not allowing rollback.
*/
if (max_rollforward < shared->kernel_version_tpm_start)
max_rollforward = shared->kernel_version_tpm_start;
if (shared->kernel_version_tpm > max_rollforward) {
VB2_DEBUG("Limiting TPM kernel version roll-forward "
"to 0x%x < 0x%x\n",
max_rollforward, shared->kernel_version_tpm);
shared->kernel_version_tpm = max_rollforward;
}
}
if ((shared->kernel_version_tpm > shared->kernel_version_tpm_start) &&
RollbackKernelWrite(shared->kernel_version_tpm)) {
VB2_DEBUG("Error writing kernel versions to TPM.\n");

17
tests/vboot_api_kernel4_tests.c
View File

@@ -53,6 +53,7 @@ static void ResetMocks(void)
memset(&vnc, 0, sizeof(vnc));
VbNvSetup(&vnc);
VbNvSet(&vnc, VBNV_KERNEL_MAX_ROLLFORWARD, 0xffffffff);
VbNvTeardown(&vnc); /* So CRC gets generated */
memset(&shared_data, 0, sizeof(shared_data));
@@ -88,7 +89,6 @@ uint32_t RollbackKernelRead(uint32_t *version)
uint32_t RollbackKernelWrite(uint32_t version)
{
TEST_EQ(version, new_version, "RollbackKernelWrite new version");
rkr_version = version;
return rkw_retval;
}
@@ -150,6 +150,7 @@ static void VbSlkTest(void)
{
ResetMocks();
test_slk(0, 0, "Normal");
TEST_EQ(rkr_version, 0x10002, " version");
/*
* If shared->flags doesn't ask for software sync, we won't notice
@@ -182,6 +183,20 @@ static void VbSlkTest(void)
test_slk(0, 0, "Don't roll forward during try B");
TEST_EQ(rkr_version, 0x10002, " version");
ResetMocks();
VbNvSet(&vnc, VBNV_KERNEL_MAX_ROLLFORWARD, 0x30005);
VbNvTeardown(&vnc);
new_version = 0x40006;
test_slk(0, 0, "Limit max roll forward");
TEST_EQ(rkr_version, 0x30005, " version");
ResetMocks();
VbNvSet(&vnc, VBNV_KERNEL_MAX_ROLLFORWARD, 0x10001);
VbNvTeardown(&vnc);
new_version = 0x40006;
test_slk(0, 0, "Max roll forward can't rollback");
TEST_EQ(rkr_version, 0x10002, " version");
ResetMocks();
vbboot_retval = VBERROR_INVALID_KERNEL_FOUND;
VbNvSet(&vnc, VBNV_RECOVERY_REQUEST, 123);