diff options
Diffstat (limited to 'firmware/2lib/2kernel.c')
| -rw-r--r-- | firmware/2lib/2kernel.c | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/firmware/2lib/2kernel.c b/firmware/2lib/2kernel.c new file mode 100644 index 00000000..f49b6dea --- /dev/null +++ b/firmware/2lib/2kernel.c @@ -0,0 +1,193 @@ +/* Copyright 2020 The Chromium OS Authors. All rights reserved. + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + * + * Kernel selection, loading, verification, and booting. + */ + +#include "2common.h" +#include "2kernel.h" +#include "2misc.h" +#include "2nvstorage.h" +#include "2rsa.h" +#include "2secdata.h" +#include "vb2_common.h" +#include "vboot_kernel.h" + +/** + * Reset any NVRAM requests. + * + * @param ctx Vboot context + * @return 1 if a reboot is required, 0 otherwise. + */ +static int vb2_reset_nv_requests(struct vb2_context *ctx) +{ + int need_reboot = 0; + + if (vb2_nv_get(ctx, VB2_NV_DISPLAY_REQUEST)) { + VB2_DEBUG("Unset display request (undo display init)\n"); + vb2_nv_set(ctx, VB2_NV_DISPLAY_REQUEST, 0); + need_reboot = 1; + } + + if (vb2_nv_get(ctx, VB2_NV_DIAG_REQUEST)) { + VB2_DEBUG("Unset diagnostic request (undo display init)\n"); + vb2_nv_set(ctx, VB2_NV_DIAG_REQUEST, 0); + need_reboot = 1; + } + + return need_reboot; +} + +vb2_error_t vb2_normal_boot(struct vb2_context *ctx) +{ + struct vb2_shared_data *sd = vb2_get_sd(ctx); + uint32_t max_rollforward = vb2_nv_get(ctx, + VB2_NV_KERNEL_MAX_ROLLFORWARD); + + /* Boot from fixed disk only */ + VB2_DEBUG("Entering\n"); + + if (vb2_reset_nv_requests(ctx)) { + VB2_DEBUG("Normal mode: reboot to reset NVRAM requests\n"); + return VBERROR_REBOOT_REQUIRED; + } + + vb2_error_t rv = VbTryLoadKernel(ctx, VB_DISK_FLAG_FIXED); + + VB2_DEBUG("Checking if TPM kernel version needs advancing\n"); + + /* + * Special case for when we're trying a slot with new firmware. + * Firmware updates also usually change the kernel key, which means + * that the new firmware can only boot a new kernel, and the old + * firmware in the previous slot can only boot the previous kernel. + * + * Don't roll-forward the kernel version, because we don't yet know if + * the new kernel will successfully boot. + */ + if (vb2_nv_get(ctx, VB2_NV_FW_RESULT) == VB2_FW_RESULT_TRYING) { + VB2_DEBUG("Trying new FW; skip kernel version roll-forward.\n"); + return rv; + } + + /* + * Limit kernel version rollforward if needed. 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 < sd->kernel_version_secdata) + max_rollforward = sd->kernel_version_secdata; + + if (sd->kernel_version > max_rollforward) { + VB2_DEBUG("Limiting TPM kernel version roll-forward " + "to %#x < %#x\n", + max_rollforward, sd->kernel_version); + + sd->kernel_version = max_rollforward; + } + + if (sd->kernel_version > sd->kernel_version_secdata) { + vb2_secdata_kernel_set(ctx, VB2_SECDATA_KERNEL_VERSIONS, + sd->kernel_version); + } + + return rv; +} + +int vb2api_is_developer_signed(struct vb2_context *ctx) +{ + struct vb2_shared_data *sd = vb2_get_sd(ctx); + + if (!sd->kernel_key_offset || !sd->kernel_key_size) { + VB2_REC_OR_DIE(ctx, "Cannot call this before kernel_phase1!\n"); + return 0; + } + + struct vb2_public_key key; + if (vb2_unpack_key(&key, vb2_member_of(sd, sd->kernel_key_offset))) + return 0; + + /* This is a debugging aid, not a security-relevant feature. There's no + reason to hardcode the whole key or waste time computing a hash. Just + spot check the starting bytes of the pseudorandom part of the key. */ + uint32_t devkey_n0inv = ctx->flags & VB2_CONTEXT_RECOVERY_MODE ? + 0x18cebcf5 : /* recovery_key.vbpubk @0x24 */ + 0xe0cd87d9; /* kernel_subkey.vbpubk @0x24 */ + + if (key.n0inv == devkey_n0inv) + return 1; + + return 0; +} + +vb2_error_t vb2api_kernel_phase1(struct vb2_context *ctx) +{ + struct vb2_shared_data *sd = vb2_get_sd(ctx); + struct vb2_workbuf wb; + struct vb2_packed_key *packed_key; + vb2_error_t rv; + + vb2_workbuf_from_ctx(ctx, &wb); + + /* + * Init secdata_kernel and secdata_fwmp spaces. No need to init + * secdata_firmware, since it was already read during firmware + * verification. Ignore errors in recovery mode. + */ + rv = vb2_secdata_kernel_init(ctx); + if (rv && !(ctx->flags & VB2_CONTEXT_RECOVERY_MODE)) { + VB2_DEBUG("TPM: init secdata_kernel returned %#x\n", rv); + vb2api_fail(ctx, VB2_RECOVERY_SECDATA_KERNEL_INIT, rv); + return rv; + } + rv = vb2_secdata_fwmp_init(ctx); + if (rv && !(ctx->flags & VB2_CONTEXT_RECOVERY_MODE)) { + VB2_DEBUG("TPM: init secdata_fwmp returned %#x\n", rv); + vb2api_fail(ctx, VB2_RECOVERY_SECDATA_FWMP_INIT, rv); + return rv; + } + + /* Read kernel version from secdata. */ + sd->kernel_version_secdata = + vb2_secdata_kernel_get(ctx, VB2_SECDATA_KERNEL_VERSIONS); + sd->kernel_version = sd->kernel_version_secdata; + + /* Find the key to use to verify the kernel keyblock */ + if ((ctx->flags & VB2_CONTEXT_RECOVERY_MODE)) { + /* Load recovery key from GBB. */ + rv = vb2_gbb_read_recovery_key(ctx, &packed_key, NULL, &wb); + if (rv) { + if (vb2_allow_recovery(ctx)) + VB2_DIE("GBB read recovery key failed.\n"); + else + /* + * If we're headed for the BROKEN screen, + * we won't need the recovery key. Just + * short-circuit with success. + */ + return VB2_SUCCESS; + } + } else { + /* Kernel subkey from firmware preamble */ + struct vb2_fw_preamble *pre; + + /* Make sure we have a firmware preamble loaded */ + if (!sd->preamble_size) + return VB2_ERROR_API_KPHASE1_PREAMBLE; + + pre = (struct vb2_fw_preamble *) + vb2_member_of(sd, sd->preamble_offset); + packed_key = &pre->kernel_subkey; + } + + sd->kernel_key_offset = vb2_offset_of(sd, packed_key); + sd->kernel_key_size = packed_key->key_offset + packed_key->key_size; + + vb2_set_workbuf_used(ctx, vb2_offset_of(sd, wb.buf)); + + if (vb2api_is_developer_signed(ctx)) + VB2_DEBUG("This is developer-signed firmware.\n"); + + return VB2_SUCCESS; +} |