Apologies for the noise. Feel free to ignore this, I had a new version with updated changelog. I'll post them shortly
On Mon, 18 Apr 2022 at 08:53, Ilias Apalodimas ilias.apalodimas@linaro.org wrote:
Currently we don't support sha384/512 for the X.509 certificate To-Be-Signed contents. Moreover if we come across such a hash we skip the check and approve the image, although the image might needs to be rejected.
It's worth noting here that efi_hash_regions() can now be reused from efi_signature_lookup_digest() and add sha348/512 support there as well
Signed-off-by: Ilias Apalodimas ilias.apalodimas@linaro.org
changes since v1:
- add an array of structs with the algo info info of a function
- checking hash_calculate result in efi_hash_regions()
include/efi_api.h | 6 +++ include/efi_loader.h | 7 +++ lib/efi_loader/efi_helper.c | 85 ++++++++++++++++++++++++++++++++++ lib/efi_loader/efi_signature.c | 76 +++++++++++++++++++++--------- 4 files changed, 151 insertions(+), 23 deletions(-)
diff --git a/include/efi_api.h b/include/efi_api.h index 982c2001728d..b9a04958f9ba 100644 --- a/include/efi_api.h +++ b/include/efi_api.h @@ -1873,6 +1873,12 @@ struct efi_system_resource_table { #define EFI_CERT_X509_SHA256_GUID \ EFI_GUID(0x3bd2a492, 0x96c0, 0x4079, 0xb4, 0x20, \ 0xfc, 0xf9, 0x8e, 0xf1, 0x03, 0xed) +#define EFI_CERT_X509_SHA384_GUID \
EFI_GUID(0x7076876e, 0x80c2, 0x4ee6, \0xaa, 0xd2, 0x28, 0xb3, 0x49, 0xa6, 0x86, 0x5b)+#define EFI_CERT_X509_SHA512_GUID \
EFI_GUID(0x446dbf63, 0x2502, 0x4cda, \0xbc, 0xfa, 0x24, 0x65, 0xd2, 0xb0, 0xfe, 0x9d)#define EFI_CERT_TYPE_PKCS7_GUID \ EFI_GUID(0x4aafd29d, 0x68df, 0x49ee, 0x8a, 0xa9, \ 0x34, 0x7d, 0x37, 0x56, 0x65, 0xa7) diff --git a/include/efi_loader.h b/include/efi_loader.h index af36639ec6a7..ce221ee9317b 100644 --- a/include/efi_loader.h +++ b/include/efi_loader.h @@ -300,6 +300,8 @@ extern const efi_guid_t efi_guid_image_security_database; extern const efi_guid_t efi_guid_sha256; extern const efi_guid_t efi_guid_cert_x509; extern const efi_guid_t efi_guid_cert_x509_sha256; +extern const efi_guid_t efi_guid_cert_x509_sha384; +extern const efi_guid_t efi_guid_cert_x509_sha512; extern const efi_guid_t efi_guid_cert_type_pkcs7;
/* GUID of RNG protocol */ @@ -671,6 +673,11 @@ efi_status_t efi_file_size(struct efi_file_handle *fh, efi_uintn_t *size); /* get a device path from a Boot#### option */ struct efi_device_path *efi_get_dp_from_boot(const efi_guid_t guid);
+/* get len, string (used in u-boot crypto from a guid */ +const char *guid_to_sha_str(const efi_guid_t *guid); +int guid_to_sha_len(const efi_guid_t *guid); +int algo_to_len(const char *algo);
/**
- efi_size_in_pages() - convert size in bytes to size in pages
diff --git a/lib/efi_loader/efi_helper.c b/lib/efi_loader/efi_helper.c index 802d39ed97b6..c186ba4a3c01 100644 --- a/lib/efi_loader/efi_helper.c +++ b/lib/efi_loader/efi_helper.c @@ -92,3 +92,88 @@ err: free(var_value); return NULL; }
+const struct guid_to_hash_map {
efi_guid_t guid;const char algo[32];u32 bits;+} guid_to_hash[] = {
{EFI_CERT_X509_SHA256_GUID,"sha256",256,},{EFI_CERT_SHA256_GUID,"sha256",256,},{EFI_CERT_X509_SHA384_GUID,"sha384",384,},{EFI_CERT_X509_SHA512_GUID,"sha512",512,},+};
+#define MAX_GUID_TO_HASH_COUNT ARRAY_SIZE(guid_to_hash)
+/** guid_to_sha_str - return the sha string e.g "sha256" for a given guid
used on EFI security databases
- @guid: guid to check
- Return: len or 0 if no match is found
- */
+const char *guid_to_sha_str(const efi_guid_t *guid) +{
size_t i;for (i = 0; i < MAX_GUID_TO_HASH_COUNT; i++) {if (!guidcmp(guid, &guid_to_hash[i].guid))return guid_to_hash[i].algo;}return NULL;+}
+/** guid_to_sha_len - return the sha size in bytes for a given guid
used on EFI security databases
- @guid: guid to check
- Return: len or 0 if no match is found
- */
+int guid_to_sha_len(const efi_guid_t *guid) +{
size_t i;for (i = 0; i < MAX_GUID_TO_HASH_COUNT; i++) {if (!guidcmp(guid, &guid_to_hash[i].guid))return guid_to_hash[i].bits / 8;}return 0;+}
+/** algo_to_len - return the sha size in bytes for a given string
- @guid: string to check
- Return: len or 0 if no match is found
- */
+int algo_to_len(const char *algo) +{
size_t i;for (i = 0; i < MAX_GUID_TO_HASH_COUNT; i++) {if (!strcmp(algo, guid_to_hash[i].algo))return guid_to_hash[i].bits / 8;}return 0;+} diff --git a/lib/efi_loader/efi_signature.c b/lib/efi_loader/efi_signature.c index 79ed077ae7dd..cf01f21b4d04 100644 --- a/lib/efi_loader/efi_signature.c +++ b/lib/efi_loader/efi_signature.c @@ -24,6 +24,8 @@ const efi_guid_t efi_guid_sha256 = EFI_CERT_SHA256_GUID; const efi_guid_t efi_guid_cert_rsa2048 = EFI_CERT_RSA2048_GUID; const efi_guid_t efi_guid_cert_x509 = EFI_CERT_X509_GUID; const efi_guid_t efi_guid_cert_x509_sha256 = EFI_CERT_X509_SHA256_GUID; +const efi_guid_t efi_guid_cert_x509_sha384 = EFI_CERT_X509_SHA384_GUID; +const efi_guid_t efi_guid_cert_x509_sha512 = EFI_CERT_X509_SHA512_GUID; const efi_guid_t efi_guid_cert_type_pkcs7 = EFI_CERT_TYPE_PKCS7_GUID;
static u8 pkcs7_hdr[] = { @@ -124,23 +126,32 @@ struct pkcs7_message *efi_parse_pkcs7_header(const void *buf,
- Return: true on success, false on error
*/ static bool efi_hash_regions(struct image_region *regs, int count,
void **hash, size_t *size)
void **hash, const char *hash_algo, int *len){
int ret;if (!hash_algo || !len)return false;*len = algo_to_len(hash_algo);if (!*len)return false;if (!*hash) {
*hash = calloc(1, SHA256_SUM_LEN);
*hash = calloc(1, *len); if (!*hash) { EFI_PRINT("Out of memory\n"); return false; } }
if (size)*size = SHA256_SUM_LEN;hash_calculate("sha256", regs, count, *hash);
ret = hash_calculate(hash_algo, regs, count, *hash);if (ret)return false;#ifdef DEBUG EFI_PRINT("hash calculated:\n"); print_hex_dump(" ", DUMP_PREFIX_OFFSET, 16, 1,
*hash, SHA256_SUM_LEN, false);
*hash, *len, false);#endif
return true;@@ -190,7 +201,6 @@ bool efi_signature_lookup_digest(struct efi_image_regions *regs, struct efi_signature_store *siglist; struct efi_sig_data *sig_data; void *hash = NULL;
size_t size = 0; bool found = false; bool hash_done = false;@@ -200,6 +210,8 @@ bool efi_signature_lookup_digest(struct efi_image_regions *regs, goto out;
for (siglist = db; siglist; siglist = siglist->next) {
int len = 0;const char *hash_algo = NULL; /* * if the hash algorithm is unsupported and we get an entry in * dbx reject the image@@ -215,8 +227,14 @@ bool efi_signature_lookup_digest(struct efi_image_regions *regs, if (guidcmp(&siglist->sig_type, &efi_guid_sha256)) continue;
hash_algo = guid_to_sha_str(&efi_guid_sha256);/** We could check size and hash_algo but efi_hash_regions()* will do that for us*/ if (!hash_done &&
!efi_hash_regions(regs->reg, regs->num, &hash, &size)) {
!efi_hash_regions(regs->reg, regs->num, &hash, hash_algo,&len)) { EFI_PRINT("Digesting an image failed\n"); break; }@@ -229,8 +247,8 @@ bool efi_signature_lookup_digest(struct efi_image_regions *regs, print_hex_dump(" ", DUMP_PREFIX_OFFSET, 16, 1, sig_data->data, sig_data->size, false); #endif
if (sig_data->size == size &&!memcmp(sig_data->data, hash, size)) {
if (sig_data->size == len &&!memcmp(sig_data->data, hash, len)) { found = true; free(hash); goto out;@@ -263,8 +281,9 @@ static bool efi_lookup_certificate(struct x509_certificate *cert, struct efi_sig_data *sig_data; struct image_region reg[1]; void *hash = NULL, *hash_tmp = NULL;
size_t size = 0;
int len = 0; bool found = false;const char *hash_algo = NULL; EFI_PRINT("%s: Enter, %p, %p\n", __func__, cert, db);@@ -278,7 +297,11 @@ static bool efi_lookup_certificate(struct x509_certificate *cert, /* calculate hash of TBSCertificate */ reg[0].data = cert->tbs; reg[0].size = cert->tbs_size;
if (!efi_hash_regions(reg, 1, &hash, &size))
/* We just need any sha256 algo to start the matching */hash_algo = guid_to_sha_str(&efi_guid_sha256);len = guid_to_sha_len(&efi_guid_sha256);if (!efi_hash_regions(reg, 1, &hash, hash_algo, &len)) goto out; EFI_PRINT("%s: searching for %s\n", __func__, cert->subject);@@ -290,6 +313,7 @@ static bool efi_lookup_certificate(struct x509_certificate *cert, for (sig_data = siglist->sig_data_list; sig_data; sig_data = sig_data->next) { struct x509_certificate *cert_tmp;
int len_tmp; cert_tmp = x509_cert_parse(sig_data->data, sig_data->size);@@ -300,12 +324,13 @@ static bool efi_lookup_certificate(struct x509_certificate *cert, cert_tmp->subject); reg[0].data = cert_tmp->tbs; reg[0].size = cert_tmp->tbs_size;
if (!efi_hash_regions(reg, 1, &hash_tmp, NULL))
if (!efi_hash_regions(reg, 1, &hash_tmp, hash_algo,&len_tmp)) goto out; x509_free_certificate(cert_tmp);
if (!memcmp(hash, hash_tmp, size)) {
if (!memcmp(hash, hash_tmp, len)) { found = true; goto out; }@@ -400,9 +425,10 @@ static bool efi_signature_check_revocation(struct pkcs7_signed_info *sinfo, struct efi_sig_data *sig_data; struct image_region reg[1]; void *hash = NULL;
size_t size = 0;
int len = 0; time64_t revoc_time; bool revoked = false;const char *hash_algo = NULL; EFI_PRINT("%s: Enter, %p, %p, %p\n", __func__, sinfo, cert, dbx);@@ -411,13 +437,14 @@ static bool efi_signature_check_revocation(struct pkcs7_signed_info *sinfo,
EFI_PRINT("Checking revocation against %s\n", cert->subject); for (siglist = dbx; siglist; siglist = siglist->next) {
if (guidcmp(&siglist->sig_type, &efi_guid_cert_x509_sha256))
hash_algo = guid_to_sha_str(&siglist->sig_type);if (!hash_algo) continue; /* calculate hash of TBSCertificate */ reg[0].data = cert->tbs; reg[0].size = cert->tbs_size;
if (!efi_hash_regions(reg, 1, &hash, &size))
if (!efi_hash_regions(reg, 1, &hash, hash_algo, &len)) goto out; for (sig_data = siglist->sig_data_list; sig_data;@@ -429,18 +456,18 @@ static bool efi_signature_check_revocation(struct pkcs7_signed_info *sinfo, * }; */ #ifdef DEBUG
if (sig_data->size >= size) {
if (sig_data->size >= len) { EFI_PRINT("hash in db:\n"); print_hex_dump(" ", DUMP_PREFIX_OFFSET, 16, 1,
sig_data->data, size, false);
sig_data->data, len, false); }#endif
if ((sig_data->size < size + sizeof(time64_t)) ||memcmp(sig_data->data, hash, size))
if ((sig_data->size < len + sizeof(time64_t)) ||memcmp(sig_data->data, hash, len)) continue;
memcpy(&revoc_time, sig_data->data + size,
memcpy(&revoc_time, sig_data->data + len, sizeof(revoc_time)); EFI_PRINT("revocation time: 0x%llx\n", revoc_time); /*@@ -488,6 +515,7 @@ bool efi_signature_verify(struct efi_image_regions *regs, goto out;
for (sinfo = msg->signed_infos; sinfo; sinfo = sinfo->next) {
int len; EFI_PRINT("Signed Info: digest algo: %s, pkey algo: %s\n", sinfo->sig->hash_algo, sinfo->sig->pkey_algo);@@ -500,7 +528,9 @@ bool efi_signature_verify(struct efi_image_regions *regs, */ if (!msg->data && !efi_hash_regions(regs->reg, regs->num,
(void **)&sinfo->sig->digest, NULL)) {
(void **)&sinfo->sig->digest,guid_to_sha_str(&efi_guid_sha256),&len)) { EFI_PRINT("Digesting an image failed\n"); goto out; }-- 2.32.0