Currently we don't support sha384/512 for the X.509 certificate in dbx. Moreover if we come across such a hash we skip the check and approve the image, although the image might needs to be rejected.

Rework the code a bit and fix it by adding an array of structs with the supported GUIDs, len and literal used in the U-Boot crypto APIs instead of hardcoding the GUID types.

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 v3: - Get rid of guid_to_sha_len() - define a local variable to efi_hash_regions() so we can use it with a NULL ptr for len changes since v2: - updated changelog (there was no v1) changes since RFC: - 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 | 6 +++ lib/efi_loader/efi_helper.c | 66 +++++++++++++++++++++++++++++ lib/efi_loader/efi_signature.c | 76 ++++++++++++++++++++++++---------- 4 files changed, 131 insertions(+), 23 deletions(-)

diff --git a/include/efi_api.h b/include/efi_api.h index c7f7873b5d48..83c01085fded 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 effb43369d96..733ee03cd77a 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 */ @@ -677,6 +679,10 @@ 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 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..849658d47bc7 100644 --- a/lib/efi_loader/efi_helper.c +++ b/lib/efi_loader/efi_helper.c @@ -92,3 +92,69 @@ 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", + SHA256_SUM_LEN * 8, + }, + { + EFI_CERT_SHA256_GUID, + "sha256", + SHA256_SUM_LEN * 8, + }, + { + EFI_CERT_X509_SHA384_GUID, + "sha384", + SHA384_SUM_LEN * 8, + }, + { + EFI_CERT_X509_SHA512_GUID, + "sha512", + SHA512_SUM_LEN * 8, + }, +}; + +#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; +} + +/** 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..ddac751d128e 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 +126,35 @@ 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, hash_len; + + if (!hash_algo) + return false; + + hash_len = algo_to_len(hash_algo); + if (!hash_len) + return false; + if (!*hash) { - *hash = calloc(1, SHA256_SUM_LEN); + *hash = calloc(1, hash_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; + + if (len) + *len = hash_len; #ifdef DEBUG EFI_PRINT("hash calculated:\n"); print_hex_dump(" ", DUMP_PREFIX_OFFSET, 16, 1, - *hash, SHA256_SUM_LEN, false); + *hash, hash_len, false); #endif

return true; @@ -190,7 +204,6 @@ 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 +213,8 @@ 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 +230,14 @@ 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 +250,8 @@ 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 +284,9 @@ 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 +300,10 @@ 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); + if (!efi_hash_regions(reg, 1, &hash, hash_algo, &len)) goto out;

EFI_PRINT("%s: searching for %s\n", __func__, cert->subject); @@ -300,12 +325,13 @@ 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, + NULL)) 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 +426,10 @@ 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 +438,14 @@ 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 +457,18 @@ 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); /* @@ -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), + NULL)) { EFI_PRINT("Digesting an image failed\n"); goto out; }