Message ID | 20200120023700.5373-10-erichte@linux.ibm.com |
---|---|
State | Superseded |
Headers | show |
Series | Add initial secure variable storage and backend drivers | expand |
Context | Check | Description |
---|---|---|
snowpatch_ozlabs/apply_patch | warning | Failed to apply on branch master (d75e82dbfbb9443efeb3f9a5921ac23605aab469) |
snowpatch_ozlabs/apply_patch | fail | Failed to apply to any branch |
On 1/19/20 9:36 PM, Eric Richter wrote: > From: Nayna Jain <nayna@linux.ibm.com> > > As part of secureboot key management, the scheme for handling key updates > is derived from tianocore reference implementation[1]. The wrappers for > holding the signed update is the Authentication Header and for holding > the public key certificate is ESL (EFI Signature List), both derived from > tianocore reference implementation[1]. > > This patch adds the support to process update queue. This involves: > 1. Verification of the update signature using the key authorized as per the > key hierarchy > 2. Handling addition/deletion of the keys > 3. Support for dbx(blacklisting of hashes) > 4. Validation checks for the updates > 5. Supporting multiple ESLs for single variable both for update/verification > 6. Timestamp check > 7. Allowing only single PK > 8. Failure Handling > > [1] https://github.com/tianocore/edk2-staging.git > > Signed-off-by: Nayna Jain <nayna@linux.ibm.com> > Signed-off-by: Eric Richter <erichte@linux.ibm.com> > --- > > V5: > - Finalizes the previous version to a complete version taking care > of validation, multiple ESLs, single PK, dbx support, timestamp checks and > failure handling. > > doc/secvar/edk2.rst | 49 ++ > include/secvar.h | 1 + > libstb/secvar/backend/Makefile.inc | 4 +- > libstb/secvar/backend/edk2-compat.c | 877 ++++++++++++++++++++++++++++ > libstb/secvar/backend/edk2.h | 243 ++++++++ > 5 files changed, 1172 insertions(+), 2 deletions(-) > create mode 100644 doc/secvar/edk2.rst > create mode 100644 libstb/secvar/backend/edk2-compat.c > create mode 100644 libstb/secvar/backend/edk2.h > > diff --git a/doc/secvar/edk2.rst b/doc/secvar/edk2.rst > new file mode 100644 > index 00000000..e0c29457 > --- /dev/null > +++ b/doc/secvar/edk2.rst > @@ -0,0 +1,49 @@ > +.. _secvar/edk2: > + > +Skiboot edk2-compatible Secure Variable Backend > +=============================================== > + > +Overview > +-------- > + > +The edk2 secure variable backend for skiboot borrows from edk2 concepts > +such as the three key hierarchy (PK, KEK, and db), and a similar > +structure. In general, variable updates must be signed with a key > +of a higher level. So, updates to the db must be signed with a key stored > +in the KEK; updates to the KEK must be signed with the PK. Updates to the > +PK must be signed with the previous PK (if any). > + > +Variables are stored in the efi signature list format, and updates are a > +signed variant that includes an authentication header. > + > +If no PK is currently enrolled, the system is considered to be in "Setup > +Mode". Any key can be enrolled without signature checks. However, once a > +PK is enrolled, the system switches to "User Mode", and each update must > +now be signed according to the hierarchy. Furthermore, when in "User > +Mode", the backend initialized the ``os-secure-mode`` device tree flag, > +signaling to the kernel that we are in secure mode. > + > +Updates are processed sequentially, in the order that they were provided > +in the update queue. If any update fails to validate, appears to be > +malformed, or any other error occurs, NO updates will not be applied. > +This includes updates that may have successfully applied prior to the > +error. The system will continue in an error state, reporting the error > +reason via the ``update-status`` device tree property. > + > +P9 Special Case for the Platform Key > +------------------------------------ > + > +Due to the powerful nature of the platform key and the lack of lockable > +flash, the edk2 backend will store the PK in TPM NV rather than PNOR on > +P9 systems. (TODO expand on this) > + > +Update Status Return Codes > +-------------------------- > + > +TODO, edk2 driver needs to actually return these properly first > + > + > +Device Tree Bindings > +-------------------- > + > +TODO You intend to fill these ? > diff --git a/include/secvar.h b/include/secvar.h > index 2875c700..8b701e00 100644 > --- a/include/secvar.h > +++ b/include/secvar.h > @@ -24,6 +24,7 @@ struct secvar_backend_driver { > }; > > extern struct secvar_storage_driver secboot_tpm_driver; > +extern struct secvar_backend_driver edk2_compatible_v1; > > int secvar_main(struct secvar_storage_driver, struct secvar_backend_driver); > > diff --git a/libstb/secvar/backend/Makefile.inc b/libstb/secvar/backend/Makefile.inc > index cc1a49fa..1c1896ab 100644 > --- a/libstb/secvar/backend/Makefile.inc > +++ b/libstb/secvar/backend/Makefile.inc > @@ -1,11 +1,11 @@ > # SPDX-License-Identifier: Apache-2.0 > # -*-Makefile-*- > > -SECVAR_BACKEND_DIR = libstb/secvar/backend > +SECVAR_BACKEND_DIR = $(SRC)/libstb/secvar/backend > > SUBDIRS += $(SECVAR_BACKEND_DIR) > > -SECVAR_BACKEND_SRCS = > +SECVAR_BACKEND_SRCS = edk2-compat.c > SECVAR_BACKEND_OBJS = $(SECVAR_BACKEND_SRCS:%.c=%.o) > SECVAR_BACKEND = $(SECVAR_BACKEND_DIR)/built-in.a > > diff --git a/libstb/secvar/backend/edk2-compat.c b/libstb/secvar/backend/edk2-compat.c > new file mode 100644 > index 00000000..b99738b1 > --- /dev/null > +++ b/libstb/secvar/backend/edk2-compat.c > @@ -0,0 +1,877 @@ > +// SPDX-License-Identifier: Apache-2.0 > +/* Copyright 2019 IBM Corp. */ > +#ifndef pr_fmt > +#define pr_fmt(fmt) "EDK2_COMPAT: " fmt > +#endif > + > +#include <opal.h> > +#include <string.h> > +#include <time.h> > +#include <unistd.h> > +#include <stdint.h> > +#include <ccan/endian/endian.h> > +#include "libstb/crypto/pkcs7/pkcs7.h" > +#include "edk2.h" > +#include "opal-api.h" > +#include "../secvar.h" > +#include "../secvar_devtree.h" > +#include "../secvar_tpmnv.h" > +#include <mbedtls/error.h> > + > +#define TPMNV_ID_EDK2_PK 0x4532504b // E2PK > + > +static bool setup_mode; > + > +//struct efi_time *timestamp_list; remove if not needed > + > +/* > + * Converts utf8 string to ucs2 > + */ > +static char *utf8_to_ucs2(const char *key, const char keylen) size_t keylen ? > +{ > + int i; > + char *str; > + str = zalloc(keylen * 2); str = NULL check ? > + > + for (i = 0; i < keylen*2; key++) { > + str[i++] = *key; > + str[i++] = '\0'; > + } > + return str; > +} > + > +/* > + * Returns true if key1 = key2 > + */ > +static bool key_equals(const char *key1, const char *key2) > +{ return !strcmp(key1, key2); > + if (memcmp(key1, key2, strlen(key2)+1) == 0) > + return true; > + > + return false; > +} > + > +/** > + * Returns the authority that can sign the given key update > + */ > +static void get_key_authority(const char *ret[3], const char *key) > +{ > + int i = 0; > + > + memset(ret, 0, sizeof(char *) * 3); Shouldn't be necessary since you are NULL-terminating the array and presumably all callers stop once they see the NULL. > + if (key_equals(key, "PK")) > + ret[i++] = "PK"; > + if (key_equals(key, "KEK")) > + ret[i++] = "PK"; > + if (key_equals(key, "db") || key_equals(key, "dbx")) { > + ret[i++] = "KEK"; > + ret[i++] = "PK"; > + } > + ret[i] = NULL; > +} > + > +/* > + * PK needs to be stored in the TPMNV space if on p9 > + * We store it using the form <u64:esl size><esl data>, the > + * extra secvar headers are unnecessary > + */ > +static int edk2_p9_load_pk(void) > +{ > + struct secvar_node *pkvar; > + uint64_t size; > + int rc; > + > + // Ensure it exists > + rc = secvar_tpmnv_alloc(TPMNV_ID_EDK2_PK, -1); check rc now that you have it > + > + // Peek to get the size > + rc = secvar_tpmnv_read(TPMNV_ID_EDK2_PK, &size, sizeof(size), 0); > + if (rc == OPAL_EMPTY) > + return 0; Is this OPAL_SUCCESS? > + else if (rc) > + return -1; Isn't there a better return code for 0 and -1. Below you return OPAL_* return codes. > + > + if (size > secvar_storage.max_var_size) > + return OPAL_RESOURCE; > + > + pkvar = alloc_secvar(size); NULL ptr check > + memcpy(pkvar->var->key, "PK", 3); > + pkvar->var->key_len = 3; > + pkvar->var->data_size = size; > + pkvar->flags |= SECVAR_FLAG_VOLATILE; > + > + rc = secvar_tpmnv_read(TPMNV_ID_EDK2_PK, pkvar->var->data, pkvar->var->data_size, sizeof(pkvar->var->data_size)); > + if (rc) > + return rc; this returns an OPAL_ error code following what I see in secvar_tpmnv_read > + > + list_add_tail(&variable_bank, &pkvar->link); > + > + return OPAL_SUCCESS; > +} > + > +/* > + * Writes the PK to the TPM. > + */ > +static int edk2_p9_write_pk(void) > +{ > + char *tmp; > + int32_t tmpsize; > + struct secvar_node *pkvar; > + int rc; > + > + pkvar = find_secvar("PK", 3, &variable_bank); find_secvar cannot do a strlen() + 1 on the name? All callers seem to have to pass the length of the string + 1. > + > + // Should not happen > + if (!pkvar) > + return OPAL_INTERNAL_ERROR; > + > + // Reset the pk flag to volatile on p9 > + pkvar->flags |= SECVAR_FLAG_VOLATILE; > + > + tmpsize = secvar_tpmnv_size(TPMNV_ID_EDK2_PK); > + if (tmpsize < 0) { > + prlog(PR_ERR, "TPMNV space for PK was not allocated properly\n"); > + return OPAL_RESOURCE; > + } > + if (tmpsize < pkvar->var->data_size + sizeof(pkvar->var->data_size)) { > + prlog(PR_ERR, "TPMNV PK space is insufficient, %d < %llu\n", tmpsize, > + // Cast needed because x86 compiler complains building the test > + (long long unsigned) pkvar->var->data_size + sizeof(pkvar->var->data_size)); > + return OPAL_RESOURCE; > + } > + > + tmp = zalloc(tmpsize); a rare NULL pointer check; good > + if (!tmp) > + return OPAL_NO_MEM; > + > + memcpy(tmp, &pkvar->var->data_size, sizeof(pkvar->var->data_size)); > + memcpy(tmp + sizeof(pkvar->var->data_size), > + pkvar->var->data, > + pkvar->var->data_size); > + > + tmpsize = pkvar->var->data_size + sizeof(pkvar->var->data_size); > + > + rc = secvar_tpmnv_write(TPMNV_ID_EDK2_PK, tmp, tmpsize, 0); > + > + free(tmp); > + > + return rc; > +} > + > +/* > + * Returns the size of the ESL. > + */ > +static int get_esl_signature_list_size(char *buf) should probably have a size_t buflen ... > +{ > + EFI_SIGNATURE_LIST list; > + > + memcpy(&list, buf, sizeof(EFI_SIGNATURE_LIST)); ... so you know you enough bytes to copy ... > + > + prlog(PR_DEBUG, "size of signature list size is %u\n", le32_to_cpu(list.SignatureListSize)); > + > + return le32_to_cpu(list.SignatureListSize); ... and access this field here > +} > + > +/* > + * Returns the size of the certificate contained in the ESL. > + */ > +static int get_esl_cert_size(char *buf) Same thing here: size_t buflen > +{ > + EFI_SIGNATURE_LIST list; > + uint32_t sigsize; > + > + memcpy(&list, buf, sizeof(EFI_SIGNATURE_LIST)); > + > + sigsize = le32_to_cpu(list.SignatureListSize) - sizeof(list) > + - le32_to_cpu(list.SignatureHeaderSize) - sizeof(uuid_t); > + > + prlog(PR_DEBUG, "sig size is %u\n", sigsize); > + return sigsize; > +} > + > +/* > + * Copies the certificate from the ESL into cert buffer. > + */ > +static int get_esl_cert(char *buf, char **cert) Also here... > +{ > + int sig_data_offset; > + int size; > + EFI_SIGNATURE_LIST list; > + > + memset(&list, 0, sizeof(EFI_SIGNATURE_LIST)); > + memcpy(&list, buf, sizeof(EFI_SIGNATURE_LIST)); Memset above seems useless ; just heats up memory :-) > + > + prlog(PR_DEBUG,"size of signature list size is %u\n", le32_to_cpu(list.SignatureListSize)); > + prlog(PR_DEBUG, "size of signature header size is %u\n", le32_to_cpu(list.SignatureHeaderSize)); > + prlog(PR_DEBUG, "size of signature size is %u\n", le32_to_cpu(list.SignatureSize)); > + sig_data_offset = sizeof(list.SignatureType) > + + sizeof(list.SignatureListSize) > + + sizeof(list.SignatureHeaderSize) > + + sizeof(list.SignatureSize) > + + le32_to_cpu(list.SignatureHeaderSize) > + + 16 * sizeof(uint8_t); > + > + size = le32_to_cpu(list.SignatureSize) - sizeof(uuid_t); > + > + memcpy(*cert, buf + sig_data_offset, size); Why do you need **cert here is you don't allocated the memory for it? Do you know *cert is big enough for this size? > + > + return size; > +} > + > +/* > + * Extracts size of the PKCS7 signed data embedded in the > + * struct Authentication 2 Descriptor Header. > + */ > +static int get_pkcs7_len(struct efi_variable_authentication_2 *auth) > +{ > + uint32_t dw_length = le32_to_cpu(auth->auth_info.hdr.dw_length); > + int size; ssize_t here or size_t ? > + > + size = dw_length - (sizeof(auth->auth_info.hdr.dw_length) > + + sizeof(auth->auth_info.hdr.w_revision) > + + sizeof(auth->auth_info.hdr.w_certificate_type) > + + sizeof(auth->auth_info.cert_type)); > + > + return size; Better not be <0 ? > +} > + > +/* > + * Return the timestamp from the Authentication 2 Descriptor. > + */ > +static int get_timestamp_from_auth(char *data, struct efi_time **timestamp) > +{ > + *timestamp = (struct efi_time *) data; I trust you can just cast it like this. Without any checks it that it does it could just be struct efi_time *get_timestamp_from_auth(char *data) But this is just a simple cast you could do where it appears. So I doubt you need the function unless you wanted to do some sanity checks here. > + > + return 0; > +} > + > +/* > + * This function outputs the Authentication 2 Descriptor in the > + * auth_buffer and returns the size of the buffer. > + */ > +static int get_auth_descriptor2(void *data, char **auth_buffer) size_t datalen ?? > +{ > + struct efi_variable_authentication_2 *auth = data; > + uint64_t auth_buffer_size; > + int len; ssize_t len > + > + if (!auth_buffer) > + return OPAL_PARAMETER; > + > + len = get_pkcs7_len(auth); > + if (len < 0) > + return OPAL_NO_MEM; > + > + auth_buffer_size = sizeof(auth->timestamp) + sizeof(auth->auth_info.hdr) > + + sizeof(auth->auth_info.cert_type) + len; > + > + *auth_buffer = zalloc(auth_buffer_size); > + if (!(*auth_buffer)) > + return OPAL_NO_MEM; > + > + memcpy(*auth_buffer, data, auth_buffer_size); Are you sure you have enough bytes in data? > + > + return auth_buffer_size; > +} > + > +/* Check that PK has single ESL */ > +static bool is_single_pk(char *data, uint64_t data_size) > +{ > + char *auth_buffer = NULL; > + uint64_t auth_buffer_size = 0; > + char *newesl = NULL; > + uint64_t new_data_size = 0; > + int esllistsize; > + > + auth_buffer_size = get_auth_descriptor2(data, &auth_buffer); > + printf("auth buffer size is %d\n", (int)auth_buffer_size); this is probably debug-only output > + free(auth_buffer); > + if (auth_buffer_size <= 0) > + return false; > + > + /* Calculate the size of new ESL data */ > + new_data_size = data_size - auth_buffer_size; > + printf("new data size is %d\n", (int)new_data_size); > + > + if (!new_data_size) > + return true; > + > + newesl = zalloc(new_data_size); NULL check > + memcpy(newesl, data + auth_buffer_size, new_data_size); > + > + esllistsize = get_esl_signature_list_size(newesl); > + printf("esl list size is %d\n", esllistsize); > + free(newesl); > + if (new_data_size > esllistsize) > + return false; > + > + return true; > +} > + > +/* > + * Initializes supported variables as empty if not loaded from > + * storage. Variables are initialized as volatile if not found. > + * Updates should clear this flag. > +ec* > + * Returns OPAL Error if anything fails in initialization > + */ > +static int edk2_compat_pre_process(void) > +{ > + struct secvar_node *pkvar; > + struct secvar_node *kekvar; > + struct secvar_node *dbvar; > + struct secvar_node *dbxvar; > + struct secvar_node *tsvar; > + > + // If we are on p9, we need to store the PK in write-lockable > + // TPMNV space, as we determine our secure mode based on if this > + // variable exists. > + // NOTE: Activation of this behavior is subject to change in a later > + // patch version, ideally the platform should be able to configure > + // whether it wants this extra protection, or to instead store > + // everything via the storage driver. > + if (proc_gen == proc_gen_p9) > + edk2_p9_load_pk(); > + > + pkvar = find_secvar("PK", 3, &variable_bank); > + if (!pkvar) { > + pkvar = alloc_secvar(0); > + if (!pkvar) > + return OPAL_NO_MEM; > + > + memcpy(pkvar->var->key, "PK", 3); > + pkvar->var->key_len = 3; a helper function like secvar_new(0, "PK", 3, SECVAR_FLAG_VOLATILE) would be good ... better yet: don't pass '3' but let alloc_secvar run strlen(). Is there a reason why pkvar->var->key_len is needed? It looks like key always has a string and key_len is strlen() + 1. Seems redundant to have to set key_len. > + pkvar->flags |= SECVAR_FLAG_VOLATILE; > + list_add_tail(&variable_bank, &pkvar->link); > + } > + if (pkvar->var->data_size == 0) > + setup_mode = true; > + else > + setup_mode = false; > + > + kekvar = find_secvar("KEK", 4, &variable_bank); > + if (!kekvar) { > + kekvar = alloc_secvar(0); > + if (!kekvar) > + return OPAL_NO_MEM; > + > + memcpy(kekvar->var->key, "KEK", 4); > + kekvar->var->key_len = 4; > + kekvar->flags |= SECVAR_FLAG_VOLATILE; ... would save some code > + list_add_tail(&variable_bank, &kekvar->link); > + } > + > + dbvar = find_secvar("db", 3, &variable_bank); > + if (!dbvar) { > + dbvar = alloc_secvar(0); > + if (!dbvar) > + return OPAL_NO_MEM; > + > + memcpy(dbvar->var->key, "db", 3); > + dbvar->var->key_len = 3; > + dbvar->flags |= SECVAR_FLAG_VOLATILE; again > + list_add_tail(&variable_bank, &dbvar->link); > + } > + > + dbxvar = find_secvar("dbx", 4, &variable_bank); > + if (!dbxvar) { > + dbxvar = alloc_secvar(0); > + if (!dbxvar) > + return OPAL_NO_MEM; > + > + memcpy(dbxvar->var->key, "dbx", 4); > + dbxvar->var->key_len = 4; > + dbxvar->flags |= SECVAR_FLAG_VOLATILE; and again > + list_add_tail(&variable_bank, &dbxvar->link); > + } > + > + tsvar = find_secvar("TS", 3, &variable_bank); > + // Should only ever happen on first boot > + if (!tsvar) { > + tsvar = alloc_secvar(sizeof(struct efi_time) * 4); > + if (!tsvar) > + return OPAL_NO_MEM; > + > + memcpy(tsvar->var->key, "TS", 3); > + tsvar->var->key_len = 3; yet again > + tsvar->var->data_size = sizeof(struct efi_time) * 4; > + memset(tsvar->var->data, 0, tsvar->var->data_size); also allow passing data_size and data to this secvar_new() > + //tsvar->flags |= SECVAR_FLAG_VOLATILE; commented ? > + list_add_tail(&variable_bank, &tsvar->link); > + } > + > + return OPAL_SUCCESS; > +}; > + > +/** > + * Returns true if we are in Setup Mode > + * > + * Setup Mode is active if we have no PK. > + * Otherwise, we are in user mode. > + */ > +/** > +static int is_setup_mode(void) bool would be better because you say you want to return 'true' > +{ > + struct secvar_node *setup; > + > + setup = find_secvar((char *)"PK", 3, &variable_bank); why cast ? > + > + // Not sure why this wouldn't exist > + if (!setup) > + return 1; true ? > + > + return !setup->var->data_size; > +} > +**/ > + > +/** > + * Update the variable with the new value. > + */ > +static int add_to_variable_bank(struct secvar *secvar, void *data, uint64_t dsize) > +{ > + struct secvar_node *node; > + > + node = find_secvar(secvar->key, secvar->key_len, &variable_bank); > + if (!node) > + return OPAL_INTERNAL_ERROR; > + > + // Expand the secvar allocated memory if needed > + if (node->size < dsize) > + if (realloc_secvar(node, dsize)) Is this call correct? Shouldn't it be node = realloc_secvar(node, dsize) or realloc_secvar(&node, dsize)? > + return OPAL_NO_MEM; > + > + node->var->data_size = dsize; > + memcpy(node->var->data, data, dsize); > + node->flags &= ~SECVAR_FLAG_VOLATILE; // Clear the volatile bit when updated > + > + return 0; OPAL_SUCCESS? > +} > + > +static struct efi_time *get_last_timestamp(char *key) const char *key > +{ > + struct secvar_node *node; > + struct efi_time *prev; > + char *timestamp_list; > + u8 off; > + > + node = find_secvar("TS", 3, &variable_bank); node NULL check ? > + if (!strncmp(key, "PK", 3)) > + off = 0; > + else if (!strncmp(key, "KEK", 4)) > + off = 1; > + else if (!strncmp(key, "db", 3)) > + off = 2; > + else if (!strncmp(key, "dbx", 4)) > + off = 3; > + else > + return NULL; // unexpected variable name? > + > + timestamp_list = node->var->data; > + if (!timestamp_list) > + return NULL; > + > + prev = (struct efi_time *) (timestamp_list + (off * sizeof(struct efi_time))); Looks like you are accessing an array return &((struct efi_time *)timestamplist)[index]; > + > + return prev; > +} > + > +// Update the TS variable with the new timestamp Sometimes comments are with /* */, this one is //. I guess you need to be more consistent. > +static int update_timestamp(char *key, struct efi_time *timestamp) > +{ > + struct efi_time *prev; > + > + prev = get_last_timestamp(key); > + if (prev == NULL) > + return OPAL_PARAMETER; > + > + memcpy(prev, timestamp, sizeof(struct efi_time)); > + > + printf("updated prev year is %d month %d day %d\n", le16_to_cpu(prev->year), prev->month, prev->day); > +// add_to_variable_bank(node->var, timestamp_list, node->var->data_size); remove if not needed > + > + return OPAL_SUCCESS; > +} > + > +static int check_timestamp(char *key, struct efi_time *timestamp) > +{ > + struct efi_time *prev; > + char *current = NULL; > + char *last =NULL; > + int s1 = 0; > + > + prev = get_last_timestamp(key); > + if (prev == NULL) > + return OPAL_PARAMETER; > + > + printf("timestamp year is %d month %d day %d\n", le16_to_cpu(timestamp->year), timestamp->month, timestamp->day); > + printf("prev year is %d month %d day %d\n", le16_to_cpu(prev->year), prev->month, prev->day); > + if (le16_to_cpu(timestamp->year) > le16_to_cpu(prev->year)) > + return OPAL_SUCCESS; > + if (le16_to_cpu(timestamp->year) < le16_to_cpu(prev->year)) > + return OPAL_PERMISSION; > + > + current = &(timestamp->month); > + last = &(prev->month); > + > + s1 = memcmp(current, last, 5); there must be something better than magic '5'; some sizeof() would look better. What are you comparing? Put a comment there. It seems to be the order of month, day, hours, minutes and seconds. > + if (s1 <= 0) { > + printf("s1 is %d\n", s1); remove debug output Equal time is reason for OPAL_PERMISSION? > + return OPAL_PERMISSION; > + } > + > + return OPAL_SUCCESS; > +} > + > +/* > + * Verify the PKCS7 signature on the signed data. > + */ > +static int verify_signature(void *auth_buffer, char *newcert, > + uint64_t new_data_size, struct secvar *avar) > +{ > + struct efi_variable_authentication_2 *auth; > + mbedtls_pkcs7 *pkcs7; > + mbedtls_x509_crt x509; > + char *checkpkcs7cert; > + char *signing_cert = NULL; > + char *x509_buf; > + int len; > + int signing_cert_size; > + int rc; > + char *errbuf; > + int eslvarsize; > + int offset = 0; > + > + auth = auth_buffer; you know you have enough bytes for this cast here ? you cannot just pass in struct efi_variable_..._2 * ? > + len = get_pkcs7_len(auth); above you compare if (len < 0) --- do this also here. > + pkcs7 = malloc(sizeof(struct mbedtls_pkcs7)); NULL pointer check > + mbedtls_pkcs7_init(pkcs7); > + > + rc = mbedtls_pkcs7_parse_der( > + (const unsigned char *)auth->auth_info.cert_data, > + (const unsigned int)len, pkcs7); > + if (rc) { > + prlog(PR_ERR, "Parsing pkcs7 failed %04x\n", rc); > + goto pkcs7out; > + } > + > + checkpkcs7cert = zalloc(2048); NULL pointer check > + mbedtls_x509_crt_info(checkpkcs7cert, 2048, "CRT:", &(pkcs7->signed_data.certs)); Does this have a return value? > + prlog(PR_DEBUG, "%s \n", checkpkcs7cert); > + free(checkpkcs7cert); > + > + prlog(PR_INFO, "Load the signing certificate from the keystore"); > + > + eslvarsize = avar->data_size; > + > + while (eslvarsize > 0) { > + prlog(PR_DEBUG, "esl var size size is %d offset is %d\n", eslvarsize, offset); > + if (eslvarsize < sizeof(EFI_SIGNATURE_LIST)) > + break; > + > + signing_cert_size = get_esl_cert_size(avar->data + offset); > + if (!signing_cert_size) { > + rc = OPAL_PERMISSION; > + break; > + } > + > + signing_cert = zalloc(signing_cert_size); NULL pointer check... also further below. > + get_esl_cert(avar->data + offset, &signing_cert); > + > + mbedtls_x509_crt_init(&x509); > + rc = mbedtls_x509_crt_parse(&x509, signing_cert, signing_cert_size); > + > + /* If failure in parsing the certificate, try next */ > + if(rc) { > + prlog(PR_INFO, "X509 certificate parsing failed %04x\n", rc); > + goto next; > + } > + > + x509_buf = zalloc(2048); unsigned char x509_buf[2048]; > + mbedtls_x509_crt_info(x509_buf, 2048, "CRT:", &x509); Check return code ? > + prlog(PR_INFO, "%s \n", x509_buf); > + free(x509_buf); > + rc = mbedtls_pkcs7_signed_data_verify(pkcs7, &x509, newcert, new_data_size); > + > + /* If find a signing certificate, you are done */ If you find ... > + if (rc == 0) { > + if (signing_cert) > + free(signing_cert); No need to check for NULL. > + mbedtls_x509_crt_free(&x509); > + prlog(PR_INFO, "Signature Verification passed\n"); > + break; > + } > + > + errbuf = zalloc(1024); this one you could have allocated above char errbuf[1024]; > + mbedtls_strerror(rc, errbuf, 1024); > + prlog(PR_INFO, "Signature Verification failed %02x %s\n", rc, errbuf); > + free(errbuf); > + > +next: > + offset += get_esl_signature_list_size(avar->data + offset); > + eslvarsize = eslvarsize - offset; > + mbedtls_x509_crt_free(&x509); > + if (signing_cert) > + free(signing_cert); again no need to check, just free() > + > + } > + > +pkcs7out: > + mbedtls_pkcs7_free(pkcs7); IMO, this function should also free(pkcs7). > + free(pkcs7); this should not be necessary > + > + return rc; > +} > + > + > +/** > + * Create the single buffer > + * name || vendor guid || attributes || timestamp || newcontent > + * which is submitted as signed by the user. > + */ > +static int get_data_to_verify(char *key, char *new_data, Return type should be char *, returning NULL if OOM. > + uint64_t new_data_size, size_t > + char **buffer, > + uint64_t *buffer_size, struct efi_time *timestamp) size_t > +{ > + le32 attr = cpu_to_le32(SECVAR_ATTRIBUTES); > + int size = 0; > + int varlen; > + char *wkey; > + uuid_t guid; > + > + if (key_equals(key, "PK") > + || key_equals(key, "KEK")) > + guid = EFI_GLOBAL_VARIABLE_GUID; > + > + if (key_equals(key, "db") else if > + || key_equals(key, "dbx")) > + guid = EFI_IMAGE_SECURITY_DATABASE_GUID; > + > + // Convert utf8 name to ucs2 width > + varlen = strlen(key) * 2; varlen should be size_t > + wkey = utf8_to_ucs2(key, strlen(key)); > + > + // Prepare the single buffer > + *buffer_size = varlen + UUID_SIZE + sizeof(attr) > + + sizeof(struct efi_time) + new_data_size; > + *buffer = zalloc(*buffer_size); null ptr check > + > + memcpy(*buffer + size, wkey, varlen); rename size to offset, probably of type off_t ? > + size = size + varlen; > + memcpy(*buffer + size, &guid, sizeof(guid)); > + size = size + sizeof(guid); > + memcpy(*buffer + size, &attr, sizeof(attr)); > + size = size + sizeof(attr); > + memcpy(*buffer + size, timestamp , sizeof(struct efi_time)); > + size = size + sizeof(struct efi_time); > + > + memcpy(*buffer + size, new_data, new_data_size); > + size = size + new_data_size; this last one isn't necessary anymore > + > + free(wkey); > + > + return 0; > +} > + > +static int edk2_compat_process(void) > +{ > + char *auth_buffer = NULL; > + uint64_t auth_buffer_size = 0; size_t > + struct efi_time *timestamp = NULL; > + const char *key_authority[3]; > + char *newesl = NULL; > + uint64_t new_data_size = 0; size_t > + char *tbhbuffer = NULL; > + uint64_t tbhbuffersize = 0; > + struct secvar_node *anode = NULL; > + struct secvar_node *node = NULL; > + int rc = 0; > + int pk_updated = 0; > + int i; > + > + //setup_mode = is_setup_mode(); > + prlog(PR_INFO, "Setup mode = %d\n", setup_mode); > + > + /* Loop through each command in the update bank. > + * If any command fails, it just loops out of the update bank. > + * It should also clear the update bank. > + */ > + list_for_each(&update_bank, node, link) { > + > + /* Submitted data is auth_2 descriptor + new ESL data > + * Extract the auth_2 2 descriptor > + */ > + printf("setup mode is %d\n", setup_mode); > + prlog(PR_INFO, "update for %s\n", node->var->key); > + auth_buffer_size = get_auth_descriptor2(node->var->data, &auth_buffer); > + if (auth_buffer_size <= 0) > + return OPAL_PARAMETER; > + > + if (node->var->data_size < auth_buffer_size) { > + rc = OPAL_PARAMETER; > + goto out; > + } > + > + rc = get_timestamp_from_auth(auth_buffer, ×tamp); > + if (rc < 0) > + goto out; > + > + rc = check_timestamp(node->var->key, timestamp); > + if (rc) > + goto out; > + > + /* Calculate the size of new ESL data */ > + new_data_size = node->var->data_size - auth_buffer_size; > + newesl = zalloc(new_data_size); > + memcpy(newesl, node->var->data + auth_buffer_size, new_data_size); > + > + if (!setup_mode) { > + /* Prepare the data to be verified */ > + rc = get_data_to_verify(node->var->key, newesl, > + new_data_size, &tbhbuffer, > + &tbhbuffersize, timestamp); > + > + /* Get the authority to verify the signature */ > + get_key_authority(key_authority, node->var->key); > + i = 0; > + > + /* Try for all the authorities that are allowed to sign. > + * For eg. db/dbx can be signed by both PK or KEK > + */ > + while (key_authority[i] != NULL) { > + prlog(PR_DEBUG, "key is %s\n", node->var->key); > + prlog(PR_DEBUG, "key authority is %s\n", key_authority[i]); > + anode = find_secvar(key_authority[i], strlen(key_authority[i]) + 1, > + &variable_bank); > + if (!anode) { > + rc = OPAL_PERMISSION; > + goto out; > + } > + if (anode->var->data_size == 0) { > + rc = OPAL_PERMISSION; > + goto out; > + } > + > + /* Verify the signature */ > + rc = verify_signature(auth_buffer, tbhbuffer, > + tbhbuffersize, anode->var); > + > + /* Break if signature verification is successful */ > + if (!rc) > + break; > + i++; > + } > + } > + > + if (rc) > + goto out; > + > + /* > + * If reached here means, signature is verified so update the > + * value in the variable bank > + */ > + add_to_variable_bank(node->var, newesl, new_data_size); Check return code ? > + // Update the TS variable with the new timestamp > + update_timestamp(node->var->key, timestamp); Check return code? > + > + /* If the PK is updated, update the secure boot state of the > + * system at the end of processing */ > + if (key_equals(node->var->key, "PK")) { > + pk_updated = 1; > + if(new_data_size == 0) > + setup_mode = true; > + else > + setup_mode = false; > + printf("setup mode is %d\n", setup_mode); > + } > + } > + > + if (pk_updated) { > + // Store the updated pk in TPMNV on p9 > + if (proc_gen == proc_gen_p9) { > + rc = edk2_p9_write_pk(); > + prlog(PR_INFO, "edk2_p9_write rc=%d\n", rc); > + } > + } > + > +out: > + if (auth_buffer) > + free(auth_buffer); > + if (newesl) > + free(newesl); > + if (tbhbuffer) > + free(tbhbuffer); no need to check > + > + clear_bank_list(&update_bank); > + > + return rc; > +} > + > +static int edk2_compat_post_process(void) > +{ > + printf("setup mode is %d\n", setup_mode); > + if (!setup_mode) { > + secvar_set_secure_mode(); > + prlog(PR_INFO, "Enforcing OS secure mode\n"); > + } > + > + return 0; > +} > + > +static bool is_pkcs7_sig_format(void *data) > +{ > + struct efi_variable_authentication_2 *auth = data; Why does this function take a void as input rather than the concrete type? > + uuid_t pkcs7_guid = EFI_CERT_TYPE_PKCS7_GUID; > + > + if(!(memcmp(&auth->auth_info.cert_type, &pkcs7_guid, 16) == 0)) 16 -> sizeof(pkcs7_guid) You first check that memcmp() returns 0 and then you invert it . Seems unnecessary and you could just invert the return value below. > + return false; > + > + return true; > +} > + > +static int edk2_compat_validate(struct secvar *var) What does this validate and what does it have to do with edk2 ? Can it return a bool? > +{ > + > + /* > + * Checks if the update is for supported > + * Non-volatile secure variales variables > + */ > + if (!key_equals(var->key, "PK") > + && !key_equals(var->key, "KEK") > + && !key_equals(var->key, "db") > + && !key_equals(var->key, "dbx")) > + return -1; > + > + /* > + * PK update should contain single ESL. > + */ > + //Not sure if we need to restrict it but, am adding as of now. > + //Feel free to remove it if you don't it as good idea Uh? > + if (key_equals(var->key, "PK")) { > + printf("check if single PK\n"); > + if (!is_single_pk(var->data, var->data_size)) { > + printf("not single pk\n"); > + return -1; > + } > + } > + > + /* > + * Check that signature type is PKCS7 > + */ > + if (!is_pkcs7_sig_format(var->data)) > + return -1; > + //Some more checks needs to be added: > + // - check guid > + // - check auth struct > + // - possibly check signature? can't add but can validate > + > + return 0; > +}; > + > +struct secvar_backend_driver edk2_compatible_v1 = { > + .pre_process = edk2_compat_pre_process, > + .process = edk2_compat_process, > + .post_process = edk2_compat_post_process, > + .validate = edk2_compat_validate, > + .compatible = "ibm,edk2-compat-v1", > +}; > diff --git a/libstb/secvar/backend/edk2.h b/libstb/secvar/backend/edk2.h > new file mode 100644 > index 00000000..29874ef7 > --- /dev/null > +++ b/libstb/secvar/backend/edk2.h > @@ -0,0 +1,243 @@ > +/* Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved. This > + * program and the accompanying materials are licensed and made available > + * under the terms and conditions of the 2-Clause BSD License which > + * accompanies this distribution. > + * > + * Redistribution and use in source and binary forms, with or without > + * modification, are permitted provided that the following conditions are met: > + * > + * 1. Redistributions of source code must retain the above copyright notice, > + * this list of conditions and the following disclaimer. > + * > + * 2. Redistributions in binary form must reproduce the above copyright > + * notice, this list of conditions and the following disclaimer in the > + * documentation and/or other materials provided with the distribution. > + * > + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" > + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE > + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE > + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE > + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR > + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF > + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS > + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN > + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) > + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE > + * POSSIBILITY OF SUCH DAMAGE. > + * > + * This file is derived from the following files referred from edk2-staging[1] repo > + * of tianocore > + * > + * MdePkg/Include/Guid/GlobalVariable.h > + * MdePkg/Include/Guid/WinCertificate.h > + * MdePkg/Include/Uefi/UefiMultiPhase.h > + * MdePkg/Include/Uefi/UefiBaseType.h > + * MdePkg/Include/Guid/ImageAuthentication.h > + * > + * [1] https://github.com/tianocore/edk2-staging > + * > + * Copyright 2019 IBM Corp. > + */ > + > +#ifndef __EDK2_H__ > +#define __EDK2_H__ > + > +#define UUID_SIZE 16 > + > +typedef struct { > + u8 b[UUID_SIZE]; This may be the first time I see u8; would think uint8_t > +} uuid_t; > + > +#define EFI_GLOBAL_VARIABLE_GUID (uuid_t){{0x61, 0xDF, 0xe4, 0x8b, 0xca, 0x93, 0xd2, 0x11, 0xaa, \ > + 0x0d, 0x00, 0xe0, 0x98, 0x03, 0x2b, 0x8c}} > + > +#define EFI_IMAGE_SECURITY_DATABASE_GUID (uuid_t){{0xcb, 0xb2, 0x19, 0xd7, 0x3a, 0x3d, 0x96, 0x45, \ > + 0xa3, 0xbc, 0xda, 0xd0, 0x0e, 0x67, 0x65, 0x6f}} > + > +#define SECVAR_ATTRIBUTES 39 > + > +/// > +/// This identifies a signature based on an X.509 certificate. If the signature is an X.509 > +/// certificate then verification of the signature of an image should validate the public > +/// key certificate in the image using certificate path verification, up to this X.509 > +/// certificate as a trusted root. The SignatureHeader size shall always be 0. The > +/// SignatureSize may vary but shall always be 16 (size of the SignatureOwner component) + > +/// the size of the certificate itself. > +/// Note: This means that each certificate will normally be in a separate EFI_SIGNATURE_LIST. > +/// > + > +#define EFI_CERT_RSA2048_GUID \ > + (UUID_INIT) (0x3c5766e8, 0x269c, 0x4e34, 0xaa, 0x14, 0xed, 0x77, 0x6e, 0x85, 0xb3, 0xb6) > + > +#define EFI_CERT_TYPE_PKCS7_GUID (uuid_t){{0x9d, 0xd2, 0xaf, 0x4a, 0xdf, 0x68, 0xee, 0x49, \ > + 0x8a, 0xa9, 0x34, 0x7d, 0x37, 0x56, 0x65, 0xa7}} > + > +#define EFI_VARIABLE_NON_VOLATILE 0x00000001 > +#define EFI_VARIABLE_BOOTSERVICE_ACCESS 0x00000002 > +#define EFI_VARIABLE_RUNTIME_ACCESS 0x00000004 > + > +/* > + * Attributes of Authenticated Variable > + */ > +#define EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS 0x00000020 > +#define EFI_VARIABLE_APPEND_WRITE 0x00000040 > +/* > + * NOTE: EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS is deprecated and should be > + * considered reserved. > + */ > +#define EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS 0x00000010 > + > +/* > + * win_certificate.w_certificate_type > + */ > +#define WIN_CERT_TYPE_PKCS_SIGNED_DATA 0x0002 > + > +#define SECURE_BOOT_MODE_ENABLE 1 > +#define SECURE_BOOT_MODE_DISABLE 0 > +/// > +/// Depricated value definition for SetupMode variable > +/// > +#define SETUP_MODE 1 > +#define USER_MODE 0 > + > +/* > + * EFI Time Abstraction: > + * Year: 1900 - 9999 > + * Month: 1 - 12 > + * Day: 1 - 31 > + * Hour: 0 - 23 > + * Minute: 0 - 59 > + * Second: 0 - 59 > + * Nanosecond: 0 - 999,999,999 > + * TimeZone: -1440 to 1440 or 2047 > + */ > +struct efi_time { > + u16 year; > + u8 month; > + u8 day; > + u8 hour; > + u8 minute; > + u8 second; > + u8 pad1; > + u32 nanosecond; > + s16 timezone; > + u8 daylight; > + u8 pad2; > +}; > +//*********************************************************************** > +// Signature Database > +//*********************************************************************** > +/// > +/// The format of a signature database. > +/// > +#pragma pack(1) > + > +typedef struct { > + /// > + /// An identifier which identifies the agent which added the signature to the list. > + /// > + uuid_t SignatureOwner; > + /// > + /// The format of the signature is defined by the SignatureType. > + /// > + unsigned char SignatureData[0]; > +} EFI_SIGNATURE_DATA; > + > +typedef struct { > + /// > + /// Type of the signature. GUID signature types are defined in below. > + /// > + uuid_t SignatureType; > + /// > + /// Total size of the signature list, including this header. > + /// > + uint32_t SignatureListSize; u32 nad uint32_t in the same file... I would go for uint(8|16|32)_t in this file just because I saw them most often being used. > + /// > + /// Size of the signature header which precedes the array of signatures. > + /// > + uint32_t SignatureHeaderSize; > + /// > + /// Size of each signature. > + /// > + uint32_t SignatureSize; > + /// > + /// Header before the array of signatures. The format of this header is specified > + /// by the SignatureType. > + /// UINT8 SignatureHeader[SignatureHeaderSize]; > + /// > + /// An array of signatures. Each signature is SignatureSize bytes in length. > + /// EFI_SIGNATURE_DATA Signatures[][SignatureSize]; > + /// > +} EFI_SIGNATURE_LIST; > + > + > +/* > + * The win_certificate structure is part of the PE/COFF specification. > + */ > +struct win_certificate { > + /* > + * The length of the entire certificate, including the length of the > + * header, in bytes. > + */ > + u32 dw_length; > + /* > + * The revision level of the WIN_CERTIFICATE structure. The current > + * revision level is 0x0200. > + */ > + u16 w_revision; > + /* > + * The certificate type. See WIN_CERT_TYPE_xxx for the UEFI certificate > + * types. The UEFI specification reserves the range of certificate type > + * values from 0x0EF0 to 0x0EFF. > + */ > + u16 w_certificate_type; > + /* > + * The following is the actual certificate. The format of > + * the certificate depends on wCertificateType. > + */ > + /// UINT8 bCertificate[ANYSIZE_ARRAY]; > +}; > + > +/* > + * Certificate which encapsulates a GUID-specific digital signature > + */ > +struct win_certificate_uefi_guid { > + /* > + * This is the standard win_certificate header, where w_certificate_type > + * is set to WIN_CERT_TYPE_EFI_GUID. > + */ > + struct win_certificate hdr; > + /* > + * This is the unique id which determines the format of the cert_data. > + */ > + uuid_t cert_type; > + /* > + * The following is the certificate data. The format of the data is > + * determined by the @cert_type. If @cert_type is > + * EFI_CERT_TYPE_RSA2048_SHA256_GUID, the @cert_data will be > + * EFI_CERT_BLOCK_RSA_2048_SHA256 structure. > + */ > + u8 cert_data[1]; > +}; > +/* > + * When the attribute EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS is set, > + * then the Data buffer shall begin with an instance of a complete (and > + * serialized) EFI_VARIABLE_AUTHENTICATION_2 descriptor. The descriptor shall be > + * followed by the new variable value and DataSize shall reflect the combined > + * size of the descriptor and the new variable value. The authentication > + * descriptor is not part of the variable data and is not returned by subsequent > + * calls to GetVariable(). > + */ > +struct efi_variable_authentication_2 { > + /* > + * For the TimeStamp value, components Pad1, Nanosecond, TimeZone, Daylight and > + * Pad2 shall be set to 0. This means that the time shall always be expressed in GMT. > + */ > + struct efi_time timestamp; > + /* > + * Only a CertType of EFI_CERT_TYPE_PKCS7_GUID is accepted. > + */ > + struct win_certificate_uefi_guid auth_info; > +}; > + > +#endif
diff --git a/doc/secvar/edk2.rst b/doc/secvar/edk2.rst new file mode 100644 index 00000000..e0c29457 --- /dev/null +++ b/doc/secvar/edk2.rst @@ -0,0 +1,49 @@ +.. _secvar/edk2: + +Skiboot edk2-compatible Secure Variable Backend +=============================================== + +Overview +-------- + +The edk2 secure variable backend for skiboot borrows from edk2 concepts +such as the three key hierarchy (PK, KEK, and db), and a similar +structure. In general, variable updates must be signed with a key +of a higher level. So, updates to the db must be signed with a key stored +in the KEK; updates to the KEK must be signed with the PK. Updates to the +PK must be signed with the previous PK (if any). + +Variables are stored in the efi signature list format, and updates are a +signed variant that includes an authentication header. + +If no PK is currently enrolled, the system is considered to be in "Setup +Mode". Any key can be enrolled without signature checks. However, once a +PK is enrolled, the system switches to "User Mode", and each update must +now be signed according to the hierarchy. Furthermore, when in "User +Mode", the backend initialized the ``os-secure-mode`` device tree flag, +signaling to the kernel that we are in secure mode. + +Updates are processed sequentially, in the order that they were provided +in the update queue. If any update fails to validate, appears to be +malformed, or any other error occurs, NO updates will not be applied. +This includes updates that may have successfully applied prior to the +error. The system will continue in an error state, reporting the error +reason via the ``update-status`` device tree property. + +P9 Special Case for the Platform Key +------------------------------------ + +Due to the powerful nature of the platform key and the lack of lockable +flash, the edk2 backend will store the PK in TPM NV rather than PNOR on +P9 systems. (TODO expand on this) + +Update Status Return Codes +-------------------------- + +TODO, edk2 driver needs to actually return these properly first + + +Device Tree Bindings +-------------------- + +TODO diff --git a/include/secvar.h b/include/secvar.h index 2875c700..8b701e00 100644 --- a/include/secvar.h +++ b/include/secvar.h @@ -24,6 +24,7 @@ struct secvar_backend_driver { }; extern struct secvar_storage_driver secboot_tpm_driver; +extern struct secvar_backend_driver edk2_compatible_v1; int secvar_main(struct secvar_storage_driver, struct secvar_backend_driver); diff --git a/libstb/secvar/backend/Makefile.inc b/libstb/secvar/backend/Makefile.inc index cc1a49fa..1c1896ab 100644 --- a/libstb/secvar/backend/Makefile.inc +++ b/libstb/secvar/backend/Makefile.inc @@ -1,11 +1,11 @@ # SPDX-License-Identifier: Apache-2.0 # -*-Makefile-*- -SECVAR_BACKEND_DIR = libstb/secvar/backend +SECVAR_BACKEND_DIR = $(SRC)/libstb/secvar/backend SUBDIRS += $(SECVAR_BACKEND_DIR) -SECVAR_BACKEND_SRCS = +SECVAR_BACKEND_SRCS = edk2-compat.c SECVAR_BACKEND_OBJS = $(SECVAR_BACKEND_SRCS:%.c=%.o) SECVAR_BACKEND = $(SECVAR_BACKEND_DIR)/built-in.a diff --git a/libstb/secvar/backend/edk2-compat.c b/libstb/secvar/backend/edk2-compat.c new file mode 100644 index 00000000..b99738b1 --- /dev/null +++ b/libstb/secvar/backend/edk2-compat.c @@ -0,0 +1,877 @@ +// SPDX-License-Identifier: Apache-2.0 +/* Copyright 2019 IBM Corp. */ +#ifndef pr_fmt +#define pr_fmt(fmt) "EDK2_COMPAT: " fmt +#endif + +#include <opal.h> +#include <string.h> +#include <time.h> +#include <unistd.h> +#include <stdint.h> +#include <ccan/endian/endian.h> +#include "libstb/crypto/pkcs7/pkcs7.h" +#include "edk2.h" +#include "opal-api.h" +#include "../secvar.h" +#include "../secvar_devtree.h" +#include "../secvar_tpmnv.h" +#include <mbedtls/error.h> + +#define TPMNV_ID_EDK2_PK 0x4532504b // E2PK + +static bool setup_mode; + +//struct efi_time *timestamp_list; + +/* + * Converts utf8 string to ucs2 + */ +static char *utf8_to_ucs2(const char *key, const char keylen) +{ + int i; + char *str; + str = zalloc(keylen * 2); + + for (i = 0; i < keylen*2; key++) { + str[i++] = *key; + str[i++] = '\0'; + } + return str; +} + +/* + * Returns true if key1 = key2 + */ +static bool key_equals(const char *key1, const char *key2) +{ + if (memcmp(key1, key2, strlen(key2)+1) == 0) + return true; + + return false; +} + +/** + * Returns the authority that can sign the given key update + */ +static void get_key_authority(const char *ret[3], const char *key) +{ + int i = 0; + + memset(ret, 0, sizeof(char *) * 3); + if (key_equals(key, "PK")) + ret[i++] = "PK"; + if (key_equals(key, "KEK")) + ret[i++] = "PK"; + if (key_equals(key, "db") || key_equals(key, "dbx")) { + ret[i++] = "KEK"; + ret[i++] = "PK"; + } + ret[i] = NULL; +} + +/* + * PK needs to be stored in the TPMNV space if on p9 + * We store it using the form <u64:esl size><esl data>, the + * extra secvar headers are unnecessary + */ +static int edk2_p9_load_pk(void) +{ + struct secvar_node *pkvar; + uint64_t size; + int rc; + + // Ensure it exists + rc = secvar_tpmnv_alloc(TPMNV_ID_EDK2_PK, -1); + + // Peek to get the size + rc = secvar_tpmnv_read(TPMNV_ID_EDK2_PK, &size, sizeof(size), 0); + if (rc == OPAL_EMPTY) + return 0; + else if (rc) + return -1; + + if (size > secvar_storage.max_var_size) + return OPAL_RESOURCE; + + pkvar = alloc_secvar(size); + memcpy(pkvar->var->key, "PK", 3); + pkvar->var->key_len = 3; + pkvar->var->data_size = size; + pkvar->flags |= SECVAR_FLAG_VOLATILE; + + rc = secvar_tpmnv_read(TPMNV_ID_EDK2_PK, pkvar->var->data, pkvar->var->data_size, sizeof(pkvar->var->data_size)); + if (rc) + return rc; + + list_add_tail(&variable_bank, &pkvar->link); + + return OPAL_SUCCESS; +} + +/* + * Writes the PK to the TPM. + */ +static int edk2_p9_write_pk(void) +{ + char *tmp; + int32_t tmpsize; + struct secvar_node *pkvar; + int rc; + + pkvar = find_secvar("PK", 3, &variable_bank); + + // Should not happen + if (!pkvar) + return OPAL_INTERNAL_ERROR; + + // Reset the pk flag to volatile on p9 + pkvar->flags |= SECVAR_FLAG_VOLATILE; + + tmpsize = secvar_tpmnv_size(TPMNV_ID_EDK2_PK); + if (tmpsize < 0) { + prlog(PR_ERR, "TPMNV space for PK was not allocated properly\n"); + return OPAL_RESOURCE; + } + if (tmpsize < pkvar->var->data_size + sizeof(pkvar->var->data_size)) { + prlog(PR_ERR, "TPMNV PK space is insufficient, %d < %llu\n", tmpsize, + // Cast needed because x86 compiler complains building the test + (long long unsigned) pkvar->var->data_size + sizeof(pkvar->var->data_size)); + return OPAL_RESOURCE; + } + + tmp = zalloc(tmpsize); + if (!tmp) + return OPAL_NO_MEM; + + memcpy(tmp, &pkvar->var->data_size, sizeof(pkvar->var->data_size)); + memcpy(tmp + sizeof(pkvar->var->data_size), + pkvar->var->data, + pkvar->var->data_size); + + tmpsize = pkvar->var->data_size + sizeof(pkvar->var->data_size); + + rc = secvar_tpmnv_write(TPMNV_ID_EDK2_PK, tmp, tmpsize, 0); + + free(tmp); + + return rc; +} + +/* + * Returns the size of the ESL. + */ +static int get_esl_signature_list_size(char *buf) +{ + EFI_SIGNATURE_LIST list; + + memcpy(&list, buf, sizeof(EFI_SIGNATURE_LIST)); + + prlog(PR_DEBUG, "size of signature list size is %u\n", le32_to_cpu(list.SignatureListSize)); + + return le32_to_cpu(list.SignatureListSize); +} + +/* + * Returns the size of the certificate contained in the ESL. + */ +static int get_esl_cert_size(char *buf) +{ + EFI_SIGNATURE_LIST list; + uint32_t sigsize; + + memcpy(&list, buf, sizeof(EFI_SIGNATURE_LIST)); + + sigsize = le32_to_cpu(list.SignatureListSize) - sizeof(list) + - le32_to_cpu(list.SignatureHeaderSize) - sizeof(uuid_t); + + prlog(PR_DEBUG, "sig size is %u\n", sigsize); + return sigsize; +} + +/* + * Copies the certificate from the ESL into cert buffer. + */ +static int get_esl_cert(char *buf, char **cert) +{ + int sig_data_offset; + int size; + EFI_SIGNATURE_LIST list; + + memset(&list, 0, sizeof(EFI_SIGNATURE_LIST)); + memcpy(&list, buf, sizeof(EFI_SIGNATURE_LIST)); + + prlog(PR_DEBUG,"size of signature list size is %u\n", le32_to_cpu(list.SignatureListSize)); + prlog(PR_DEBUG, "size of signature header size is %u\n", le32_to_cpu(list.SignatureHeaderSize)); + prlog(PR_DEBUG, "size of signature size is %u\n", le32_to_cpu(list.SignatureSize)); + sig_data_offset = sizeof(list.SignatureType) + + sizeof(list.SignatureListSize) + + sizeof(list.SignatureHeaderSize) + + sizeof(list.SignatureSize) + + le32_to_cpu(list.SignatureHeaderSize) + + 16 * sizeof(uint8_t); + + size = le32_to_cpu(list.SignatureSize) - sizeof(uuid_t); + + memcpy(*cert, buf + sig_data_offset, size); + + return size; +} + +/* + * Extracts size of the PKCS7 signed data embedded in the + * struct Authentication 2 Descriptor Header. + */ +static int get_pkcs7_len(struct efi_variable_authentication_2 *auth) +{ + uint32_t dw_length = le32_to_cpu(auth->auth_info.hdr.dw_length); + int size; + + size = dw_length - (sizeof(auth->auth_info.hdr.dw_length) + + sizeof(auth->auth_info.hdr.w_revision) + + sizeof(auth->auth_info.hdr.w_certificate_type) + + sizeof(auth->auth_info.cert_type)); + + return size; +} + +/* + * Return the timestamp from the Authentication 2 Descriptor. + */ +static int get_timestamp_from_auth(char *data, struct efi_time **timestamp) +{ + *timestamp = (struct efi_time *) data; + + return 0; +} + +/* + * This function outputs the Authentication 2 Descriptor in the + * auth_buffer and returns the size of the buffer. + */ +static int get_auth_descriptor2(void *data, char **auth_buffer) +{ + struct efi_variable_authentication_2 *auth = data; + uint64_t auth_buffer_size; + int len; + + if (!auth_buffer) + return OPAL_PARAMETER; + + len = get_pkcs7_len(auth); + if (len < 0) + return OPAL_NO_MEM; + + auth_buffer_size = sizeof(auth->timestamp) + sizeof(auth->auth_info.hdr) + + sizeof(auth->auth_info.cert_type) + len; + + *auth_buffer = zalloc(auth_buffer_size); + if (!(*auth_buffer)) + return OPAL_NO_MEM; + + memcpy(*auth_buffer, data, auth_buffer_size); + + return auth_buffer_size; +} + +/* Check that PK has single ESL */ +static bool is_single_pk(char *data, uint64_t data_size) +{ + char *auth_buffer = NULL; + uint64_t auth_buffer_size = 0; + char *newesl = NULL; + uint64_t new_data_size = 0; + int esllistsize; + + auth_buffer_size = get_auth_descriptor2(data, &auth_buffer); + printf("auth buffer size is %d\n", (int)auth_buffer_size); + free(auth_buffer); + if (auth_buffer_size <= 0) + return false; + + /* Calculate the size of new ESL data */ + new_data_size = data_size - auth_buffer_size; + printf("new data size is %d\n", (int)new_data_size); + + if (!new_data_size) + return true; + + newesl = zalloc(new_data_size); + memcpy(newesl, data + auth_buffer_size, new_data_size); + + esllistsize = get_esl_signature_list_size(newesl); + printf("esl list size is %d\n", esllistsize); + free(newesl); + if (new_data_size > esllistsize) + return false; + + return true; +} + +/* + * Initializes supported variables as empty if not loaded from + * storage. Variables are initialized as volatile if not found. + * Updates should clear this flag. +ec* + * Returns OPAL Error if anything fails in initialization + */ +static int edk2_compat_pre_process(void) +{ + struct secvar_node *pkvar; + struct secvar_node *kekvar; + struct secvar_node *dbvar; + struct secvar_node *dbxvar; + struct secvar_node *tsvar; + + // If we are on p9, we need to store the PK in write-lockable + // TPMNV space, as we determine our secure mode based on if this + // variable exists. + // NOTE: Activation of this behavior is subject to change in a later + // patch version, ideally the platform should be able to configure + // whether it wants this extra protection, or to instead store + // everything via the storage driver. + if (proc_gen == proc_gen_p9) + edk2_p9_load_pk(); + + pkvar = find_secvar("PK", 3, &variable_bank); + if (!pkvar) { + pkvar = alloc_secvar(0); + if (!pkvar) + return OPAL_NO_MEM; + + memcpy(pkvar->var->key, "PK", 3); + pkvar->var->key_len = 3; + pkvar->flags |= SECVAR_FLAG_VOLATILE; + list_add_tail(&variable_bank, &pkvar->link); + } + if (pkvar->var->data_size == 0) + setup_mode = true; + else + setup_mode = false; + + kekvar = find_secvar("KEK", 4, &variable_bank); + if (!kekvar) { + kekvar = alloc_secvar(0); + if (!kekvar) + return OPAL_NO_MEM; + + memcpy(kekvar->var->key, "KEK", 4); + kekvar->var->key_len = 4; + kekvar->flags |= SECVAR_FLAG_VOLATILE; + list_add_tail(&variable_bank, &kekvar->link); + } + + dbvar = find_secvar("db", 3, &variable_bank); + if (!dbvar) { + dbvar = alloc_secvar(0); + if (!dbvar) + return OPAL_NO_MEM; + + memcpy(dbvar->var->key, "db", 3); + dbvar->var->key_len = 3; + dbvar->flags |= SECVAR_FLAG_VOLATILE; + list_add_tail(&variable_bank, &dbvar->link); + } + + dbxvar = find_secvar("dbx", 4, &variable_bank); + if (!dbxvar) { + dbxvar = alloc_secvar(0); + if (!dbxvar) + return OPAL_NO_MEM; + + memcpy(dbxvar->var->key, "dbx", 4); + dbxvar->var->key_len = 4; + dbxvar->flags |= SECVAR_FLAG_VOLATILE; + list_add_tail(&variable_bank, &dbxvar->link); + } + + tsvar = find_secvar("TS", 3, &variable_bank); + // Should only ever happen on first boot + if (!tsvar) { + tsvar = alloc_secvar(sizeof(struct efi_time) * 4); + if (!tsvar) + return OPAL_NO_MEM; + + memcpy(tsvar->var->key, "TS", 3); + tsvar->var->key_len = 3; + tsvar->var->data_size = sizeof(struct efi_time) * 4; + memset(tsvar->var->data, 0, tsvar->var->data_size); + //tsvar->flags |= SECVAR_FLAG_VOLATILE; + list_add_tail(&variable_bank, &tsvar->link); + } + + return OPAL_SUCCESS; +}; + +/** + * Returns true if we are in Setup Mode + * + * Setup Mode is active if we have no PK. + * Otherwise, we are in user mode. + */ +/** +static int is_setup_mode(void) +{ + struct secvar_node *setup; + + setup = find_secvar((char *)"PK", 3, &variable_bank); + + // Not sure why this wouldn't exist + if (!setup) + return 1; + + return !setup->var->data_size; +} +**/ + +/** + * Update the variable with the new value. + */ +static int add_to_variable_bank(struct secvar *secvar, void *data, uint64_t dsize) +{ + struct secvar_node *node; + + node = find_secvar(secvar->key, secvar->key_len, &variable_bank); + if (!node) + return OPAL_INTERNAL_ERROR; + + // Expand the secvar allocated memory if needed + if (node->size < dsize) + if (realloc_secvar(node, dsize)) + return OPAL_NO_MEM; + + node->var->data_size = dsize; + memcpy(node->var->data, data, dsize); + node->flags &= ~SECVAR_FLAG_VOLATILE; // Clear the volatile bit when updated + + return 0; +} + +static struct efi_time *get_last_timestamp(char *key) +{ + struct secvar_node *node; + struct efi_time *prev; + char *timestamp_list; + u8 off; + + node = find_secvar("TS", 3, &variable_bank); + if (!strncmp(key, "PK", 3)) + off = 0; + else if (!strncmp(key, "KEK", 4)) + off = 1; + else if (!strncmp(key, "db", 3)) + off = 2; + else if (!strncmp(key, "dbx", 4)) + off = 3; + else + return NULL; // unexpected variable name? + + timestamp_list = node->var->data; + if (!timestamp_list) + return NULL; + + prev = (struct efi_time *) (timestamp_list + (off * sizeof(struct efi_time))); + + return prev; +} + +// Update the TS variable with the new timestamp +static int update_timestamp(char *key, struct efi_time *timestamp) +{ + struct efi_time *prev; + + prev = get_last_timestamp(key); + if (prev == NULL) + return OPAL_PARAMETER; + + memcpy(prev, timestamp, sizeof(struct efi_time)); + + printf("updated prev year is %d month %d day %d\n", le16_to_cpu(prev->year), prev->month, prev->day); +// add_to_variable_bank(node->var, timestamp_list, node->var->data_size); + + return OPAL_SUCCESS; +} + +static int check_timestamp(char *key, struct efi_time *timestamp) +{ + struct efi_time *prev; + char *current = NULL; + char *last =NULL; + int s1 = 0; + + prev = get_last_timestamp(key); + if (prev == NULL) + return OPAL_PARAMETER; + + printf("timestamp year is %d month %d day %d\n", le16_to_cpu(timestamp->year), timestamp->month, timestamp->day); + printf("prev year is %d month %d day %d\n", le16_to_cpu(prev->year), prev->month, prev->day); + if (le16_to_cpu(timestamp->year) > le16_to_cpu(prev->year)) + return OPAL_SUCCESS; + if (le16_to_cpu(timestamp->year) < le16_to_cpu(prev->year)) + return OPAL_PERMISSION; + + current = &(timestamp->month); + last = &(prev->month); + + s1 = memcmp(current, last, 5); + if (s1 <= 0) { + printf("s1 is %d\n", s1); + return OPAL_PERMISSION; + } + + return OPAL_SUCCESS; +} + +/* + * Verify the PKCS7 signature on the signed data. + */ +static int verify_signature(void *auth_buffer, char *newcert, + uint64_t new_data_size, struct secvar *avar) +{ + struct efi_variable_authentication_2 *auth; + mbedtls_pkcs7 *pkcs7; + mbedtls_x509_crt x509; + char *checkpkcs7cert; + char *signing_cert = NULL; + char *x509_buf; + int len; + int signing_cert_size; + int rc; + char *errbuf; + int eslvarsize; + int offset = 0; + + auth = auth_buffer; + len = get_pkcs7_len(auth); + pkcs7 = malloc(sizeof(struct mbedtls_pkcs7)); + mbedtls_pkcs7_init(pkcs7); + + rc = mbedtls_pkcs7_parse_der( + (const unsigned char *)auth->auth_info.cert_data, + (const unsigned int)len, pkcs7); + if (rc) { + prlog(PR_ERR, "Parsing pkcs7 failed %04x\n", rc); + goto pkcs7out; + } + + checkpkcs7cert = zalloc(2048); + mbedtls_x509_crt_info(checkpkcs7cert, 2048, "CRT:", &(pkcs7->signed_data.certs)); + prlog(PR_DEBUG, "%s \n", checkpkcs7cert); + free(checkpkcs7cert); + + prlog(PR_INFO, "Load the signing certificate from the keystore"); + + eslvarsize = avar->data_size; + + while (eslvarsize > 0) { + prlog(PR_DEBUG, "esl var size size is %d offset is %d\n", eslvarsize, offset); + if (eslvarsize < sizeof(EFI_SIGNATURE_LIST)) + break; + + signing_cert_size = get_esl_cert_size(avar->data + offset); + if (!signing_cert_size) { + rc = OPAL_PERMISSION; + break; + } + + signing_cert = zalloc(signing_cert_size); + get_esl_cert(avar->data + offset, &signing_cert); + + mbedtls_x509_crt_init(&x509); + rc = mbedtls_x509_crt_parse(&x509, signing_cert, signing_cert_size); + + /* If failure in parsing the certificate, try next */ + if(rc) { + prlog(PR_INFO, "X509 certificate parsing failed %04x\n", rc); + goto next; + } + + x509_buf = zalloc(2048); + mbedtls_x509_crt_info(x509_buf, 2048, "CRT:", &x509); + prlog(PR_INFO, "%s \n", x509_buf); + free(x509_buf); + rc = mbedtls_pkcs7_signed_data_verify(pkcs7, &x509, newcert, new_data_size); + + /* If find a signing certificate, you are done */ + if (rc == 0) { + if (signing_cert) + free(signing_cert); + mbedtls_x509_crt_free(&x509); + prlog(PR_INFO, "Signature Verification passed\n"); + break; + } + + errbuf = zalloc(1024); + mbedtls_strerror(rc, errbuf, 1024); + prlog(PR_INFO, "Signature Verification failed %02x %s\n", rc, errbuf); + free(errbuf); + +next: + offset += get_esl_signature_list_size(avar->data + offset); + eslvarsize = eslvarsize - offset; + mbedtls_x509_crt_free(&x509); + if (signing_cert) + free(signing_cert); + + } + +pkcs7out: + mbedtls_pkcs7_free(pkcs7); + free(pkcs7); + + return rc; +} + + +/** + * Create the single buffer + * name || vendor guid || attributes || timestamp || newcontent + * which is submitted as signed by the user. + */ +static int get_data_to_verify(char *key, char *new_data, + uint64_t new_data_size, + char **buffer, + uint64_t *buffer_size, struct efi_time *timestamp) +{ + le32 attr = cpu_to_le32(SECVAR_ATTRIBUTES); + int size = 0; + int varlen; + char *wkey; + uuid_t guid; + + if (key_equals(key, "PK") + || key_equals(key, "KEK")) + guid = EFI_GLOBAL_VARIABLE_GUID; + + if (key_equals(key, "db") + || key_equals(key, "dbx")) + guid = EFI_IMAGE_SECURITY_DATABASE_GUID; + + // Convert utf8 name to ucs2 width + varlen = strlen(key) * 2; + wkey = utf8_to_ucs2(key, strlen(key)); + + // Prepare the single buffer + *buffer_size = varlen + UUID_SIZE + sizeof(attr) + + sizeof(struct efi_time) + new_data_size; + *buffer = zalloc(*buffer_size); + + memcpy(*buffer + size, wkey, varlen); + size = size + varlen; + memcpy(*buffer + size, &guid, sizeof(guid)); + size = size + sizeof(guid); + memcpy(*buffer + size, &attr, sizeof(attr)); + size = size + sizeof(attr); + memcpy(*buffer + size, timestamp , sizeof(struct efi_time)); + size = size + sizeof(struct efi_time); + + memcpy(*buffer + size, new_data, new_data_size); + size = size + new_data_size; + + free(wkey); + + return 0; +} + +static int edk2_compat_process(void) +{ + char *auth_buffer = NULL; + uint64_t auth_buffer_size = 0; + struct efi_time *timestamp = NULL; + const char *key_authority[3]; + char *newesl = NULL; + uint64_t new_data_size = 0; + char *tbhbuffer = NULL; + uint64_t tbhbuffersize = 0; + struct secvar_node *anode = NULL; + struct secvar_node *node = NULL; + int rc = 0; + int pk_updated = 0; + int i; + + //setup_mode = is_setup_mode(); + prlog(PR_INFO, "Setup mode = %d\n", setup_mode); + + /* Loop through each command in the update bank. + * If any command fails, it just loops out of the update bank. + * It should also clear the update bank. + */ + list_for_each(&update_bank, node, link) { + + /* Submitted data is auth_2 descriptor + new ESL data + * Extract the auth_2 2 descriptor + */ + printf("setup mode is %d\n", setup_mode); + prlog(PR_INFO, "update for %s\n", node->var->key); + auth_buffer_size = get_auth_descriptor2(node->var->data, &auth_buffer); + if (auth_buffer_size <= 0) + return OPAL_PARAMETER; + + if (node->var->data_size < auth_buffer_size) { + rc = OPAL_PARAMETER; + goto out; + } + + rc = get_timestamp_from_auth(auth_buffer, ×tamp); + if (rc < 0) + goto out; + + rc = check_timestamp(node->var->key, timestamp); + if (rc) + goto out; + + /* Calculate the size of new ESL data */ + new_data_size = node->var->data_size - auth_buffer_size; + newesl = zalloc(new_data_size); + memcpy(newesl, node->var->data + auth_buffer_size, new_data_size); + + if (!setup_mode) { + /* Prepare the data to be verified */ + rc = get_data_to_verify(node->var->key, newesl, + new_data_size, &tbhbuffer, + &tbhbuffersize, timestamp); + + /* Get the authority to verify the signature */ + get_key_authority(key_authority, node->var->key); + i = 0; + + /* Try for all the authorities that are allowed to sign. + * For eg. db/dbx can be signed by both PK or KEK + */ + while (key_authority[i] != NULL) { + prlog(PR_DEBUG, "key is %s\n", node->var->key); + prlog(PR_DEBUG, "key authority is %s\n", key_authority[i]); + anode = find_secvar(key_authority[i], strlen(key_authority[i]) + 1, + &variable_bank); + if (!anode) { + rc = OPAL_PERMISSION; + goto out; + } + if (anode->var->data_size == 0) { + rc = OPAL_PERMISSION; + goto out; + } + + /* Verify the signature */ + rc = verify_signature(auth_buffer, tbhbuffer, + tbhbuffersize, anode->var); + + /* Break if signature verification is successful */ + if (!rc) + break; + i++; + } + } + + if (rc) + goto out; + + /* + * If reached here means, signature is verified so update the + * value in the variable bank + */ + add_to_variable_bank(node->var, newesl, new_data_size); + // Update the TS variable with the new timestamp + update_timestamp(node->var->key, timestamp); + + /* If the PK is updated, update the secure boot state of the + * system at the end of processing */ + if (key_equals(node->var->key, "PK")) { + pk_updated = 1; + if(new_data_size == 0) + setup_mode = true; + else + setup_mode = false; + printf("setup mode is %d\n", setup_mode); + } + } + + if (pk_updated) { + // Store the updated pk in TPMNV on p9 + if (proc_gen == proc_gen_p9) { + rc = edk2_p9_write_pk(); + prlog(PR_INFO, "edk2_p9_write rc=%d\n", rc); + } + } + +out: + if (auth_buffer) + free(auth_buffer); + if (newesl) + free(newesl); + if (tbhbuffer) + free(tbhbuffer); + + clear_bank_list(&update_bank); + + return rc; +} + +static int edk2_compat_post_process(void) +{ + printf("setup mode is %d\n", setup_mode); + if (!setup_mode) { + secvar_set_secure_mode(); + prlog(PR_INFO, "Enforcing OS secure mode\n"); + } + + return 0; +} + +static bool is_pkcs7_sig_format(void *data) +{ + struct efi_variable_authentication_2 *auth = data; + uuid_t pkcs7_guid = EFI_CERT_TYPE_PKCS7_GUID; + + if(!(memcmp(&auth->auth_info.cert_type, &pkcs7_guid, 16) == 0)) + return false; + + return true; +} + +static int edk2_compat_validate(struct secvar *var) +{ + + /* + * Checks if the update is for supported + * Non-volatile secure variales + */ + if (!key_equals(var->key, "PK") + && !key_equals(var->key, "KEK") + && !key_equals(var->key, "db") + && !key_equals(var->key, "dbx")) + return -1; + + /* + * PK update should contain single ESL. + */ + //Not sure if we need to restrict it but, am adding as of now. + //Feel free to remove it if you don't it as good idea + if (key_equals(var->key, "PK")) { + printf("check if single PK\n"); + if (!is_single_pk(var->data, var->data_size)) { + printf("not single pk\n"); + return -1; + } + } + + /* + * Check that signature type is PKCS7 + */ + if (!is_pkcs7_sig_format(var->data)) + return -1; + //Some more checks needs to be added: + // - check guid + // - check auth struct + // - possibly check signature? can't add but can validate + + return 0; +}; + +struct secvar_backend_driver edk2_compatible_v1 = { + .pre_process = edk2_compat_pre_process, + .process = edk2_compat_process, + .post_process = edk2_compat_post_process, + .validate = edk2_compat_validate, + .compatible = "ibm,edk2-compat-v1", +}; diff --git a/libstb/secvar/backend/edk2.h b/libstb/secvar/backend/edk2.h new file mode 100644 index 00000000..29874ef7 --- /dev/null +++ b/libstb/secvar/backend/edk2.h @@ -0,0 +1,243 @@ +/* Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved. This + * program and the accompanying materials are licensed and made available + * under the terms and conditions of the 2-Clause BSD License which + * accompanies this distribution. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + * This file is derived from the following files referred from edk2-staging[1] repo + * of tianocore + * + * MdePkg/Include/Guid/GlobalVariable.h + * MdePkg/Include/Guid/WinCertificate.h + * MdePkg/Include/Uefi/UefiMultiPhase.h + * MdePkg/Include/Uefi/UefiBaseType.h + * MdePkg/Include/Guid/ImageAuthentication.h + * + * [1] https://github.com/tianocore/edk2-staging + * + * Copyright 2019 IBM Corp. + */ + +#ifndef __EDK2_H__ +#define __EDK2_H__ + +#define UUID_SIZE 16 + +typedef struct { + u8 b[UUID_SIZE]; +} uuid_t; + +#define EFI_GLOBAL_VARIABLE_GUID (uuid_t){{0x61, 0xDF, 0xe4, 0x8b, 0xca, 0x93, 0xd2, 0x11, 0xaa, \ + 0x0d, 0x00, 0xe0, 0x98, 0x03, 0x2b, 0x8c}} + +#define EFI_IMAGE_SECURITY_DATABASE_GUID (uuid_t){{0xcb, 0xb2, 0x19, 0xd7, 0x3a, 0x3d, 0x96, 0x45, \ + 0xa3, 0xbc, 0xda, 0xd0, 0x0e, 0x67, 0x65, 0x6f}} + +#define SECVAR_ATTRIBUTES 39 + +/// +/// This identifies a signature based on an X.509 certificate. If the signature is an X.509 +/// certificate then verification of the signature of an image should validate the public +/// key certificate in the image using certificate path verification, up to this X.509 +/// certificate as a trusted root. The SignatureHeader size shall always be 0. The +/// SignatureSize may vary but shall always be 16 (size of the SignatureOwner component) + +/// the size of the certificate itself. +/// Note: This means that each certificate will normally be in a separate EFI_SIGNATURE_LIST. +/// + +#define EFI_CERT_RSA2048_GUID \ + (UUID_INIT) (0x3c5766e8, 0x269c, 0x4e34, 0xaa, 0x14, 0xed, 0x77, 0x6e, 0x85, 0xb3, 0xb6) + +#define EFI_CERT_TYPE_PKCS7_GUID (uuid_t){{0x9d, 0xd2, 0xaf, 0x4a, 0xdf, 0x68, 0xee, 0x49, \ + 0x8a, 0xa9, 0x34, 0x7d, 0x37, 0x56, 0x65, 0xa7}} + +#define EFI_VARIABLE_NON_VOLATILE 0x00000001 +#define EFI_VARIABLE_BOOTSERVICE_ACCESS 0x00000002 +#define EFI_VARIABLE_RUNTIME_ACCESS 0x00000004 + +/* + * Attributes of Authenticated Variable + */ +#define EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS 0x00000020 +#define EFI_VARIABLE_APPEND_WRITE 0x00000040 +/* + * NOTE: EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS is deprecated and should be + * considered reserved. + */ +#define EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS 0x00000010 + +/* + * win_certificate.w_certificate_type + */ +#define WIN_CERT_TYPE_PKCS_SIGNED_DATA 0x0002 + +#define SECURE_BOOT_MODE_ENABLE 1 +#define SECURE_BOOT_MODE_DISABLE 0 +/// +/// Depricated value definition for SetupMode variable +/// +#define SETUP_MODE 1 +#define USER_MODE 0 + +/* + * EFI Time Abstraction: + * Year: 1900 - 9999 + * Month: 1 - 12 + * Day: 1 - 31 + * Hour: 0 - 23 + * Minute: 0 - 59 + * Second: 0 - 59 + * Nanosecond: 0 - 999,999,999 + * TimeZone: -1440 to 1440 or 2047 + */ +struct efi_time { + u16 year; + u8 month; + u8 day; + u8 hour; + u8 minute; + u8 second; + u8 pad1; + u32 nanosecond; + s16 timezone; + u8 daylight; + u8 pad2; +}; +//*********************************************************************** +// Signature Database +//*********************************************************************** +/// +/// The format of a signature database. +/// +#pragma pack(1) + +typedef struct { + /// + /// An identifier which identifies the agent which added the signature to the list. + /// + uuid_t SignatureOwner; + /// + /// The format of the signature is defined by the SignatureType. + /// + unsigned char SignatureData[0]; +} EFI_SIGNATURE_DATA; + +typedef struct { + /// + /// Type of the signature. GUID signature types are defined in below. + /// + uuid_t SignatureType; + /// + /// Total size of the signature list, including this header. + /// + uint32_t SignatureListSize; + /// + /// Size of the signature header which precedes the array of signatures. + /// + uint32_t SignatureHeaderSize; + /// + /// Size of each signature. + /// + uint32_t SignatureSize; + /// + /// Header before the array of signatures. The format of this header is specified + /// by the SignatureType. + /// UINT8 SignatureHeader[SignatureHeaderSize]; + /// + /// An array of signatures. Each signature is SignatureSize bytes in length. + /// EFI_SIGNATURE_DATA Signatures[][SignatureSize]; + /// +} EFI_SIGNATURE_LIST; + + +/* + * The win_certificate structure is part of the PE/COFF specification. + */ +struct win_certificate { + /* + * The length of the entire certificate, including the length of the + * header, in bytes. + */ + u32 dw_length; + /* + * The revision level of the WIN_CERTIFICATE structure. The current + * revision level is 0x0200. + */ + u16 w_revision; + /* + * The certificate type. See WIN_CERT_TYPE_xxx for the UEFI certificate + * types. The UEFI specification reserves the range of certificate type + * values from 0x0EF0 to 0x0EFF. + */ + u16 w_certificate_type; + /* + * The following is the actual certificate. The format of + * the certificate depends on wCertificateType. + */ + /// UINT8 bCertificate[ANYSIZE_ARRAY]; +}; + +/* + * Certificate which encapsulates a GUID-specific digital signature + */ +struct win_certificate_uefi_guid { + /* + * This is the standard win_certificate header, where w_certificate_type + * is set to WIN_CERT_TYPE_EFI_GUID. + */ + struct win_certificate hdr; + /* + * This is the unique id which determines the format of the cert_data. + */ + uuid_t cert_type; + /* + * The following is the certificate data. The format of the data is + * determined by the @cert_type. If @cert_type is + * EFI_CERT_TYPE_RSA2048_SHA256_GUID, the @cert_data will be + * EFI_CERT_BLOCK_RSA_2048_SHA256 structure. + */ + u8 cert_data[1]; +}; +/* + * When the attribute EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS is set, + * then the Data buffer shall begin with an instance of a complete (and + * serialized) EFI_VARIABLE_AUTHENTICATION_2 descriptor. The descriptor shall be + * followed by the new variable value and DataSize shall reflect the combined + * size of the descriptor and the new variable value. The authentication + * descriptor is not part of the variable data and is not returned by subsequent + * calls to GetVariable(). + */ +struct efi_variable_authentication_2 { + /* + * For the TimeStamp value, components Pad1, Nanosecond, TimeZone, Daylight and + * Pad2 shall be set to 0. This means that the time shall always be expressed in GMT. + */ + struct efi_time timestamp; + /* + * Only a CertType of EFI_CERT_TYPE_PKCS7_GUID is accepted. + */ + struct win_certificate_uefi_guid auth_info; +}; + +#endif