Introducing the following GRUB commands to manage certificate/binary
hashes.
1. append_list_dbx:
Show the list of distrusted certificates and binary/certificate
hashes from the dbx list.
2. append_add_db_hash:
Add the trusted binary hash to the db list.
3. append_add_dbx_hash:
Add the distrusted certificate/binary hash to the dbx list.
Note that if signature verification (check_appended_signature) is set to
enforce,
the append_add_db_hash and append_add_dbx_hash commands only accept the
file ‘hash_file’ that is signed with an appended signature.
Signed-off-by: Sudhakar Kuppusamy <sudha...@linux.ibm.com>
---
grub-core/commands/appendedsig/appendedsig.c | 276 +++++++++++++++++++
include/grub/file.h | 2 +
2 files changed, 278 insertions(+)
diff --git a/grub-core/commands/appendedsig/appendedsig.c
b/grub-core/commands/appendedsig/appendedsig.c
index 45075991e..c523a7acb 100644
--- a/grub-core/commands/appendedsig/appendedsig.c
+++ b/grub-core/commands/appendedsig/appendedsig.c
@@ -52,6 +52,9 @@ GRUB_MOD_LICENSE ("GPLv3+");
#define SHA384_HASH_LEN 48
#define SHA512_HASH_LEN 64
+#define OPTION_BINARY_HASH 0
+#define OPTION_CERT_HASH 1
+
/*
* This structure is extracted from scripts/sign-file.c in the linux kernel
* source. It was licensed as LGPLv2.1+, which is GPLv3+ compatible.
@@ -125,6 +128,13 @@ static grub_pks_t *pks_keystore;
/* Appended signature size. */
static grub_size_t append_sig_len = 0;
+static const struct grub_arg_option options[] =
+{
+ {"binary-hash", 'b', 0, N_("hash file of the binary."), 0,
ARG_TYPE_PATHNAME},
+ {"cert-hash", 'c', 1, N_("hash file of the certificate."), 0,
ARG_TYPE_PATHNAME},
+ {0, 0, 0, 0, 0, 0}
+};
+
static grub_ssize_t
pseudo_read (struct grub_file *file, char *buf, grub_size_t len)
{
@@ -546,6 +556,69 @@ remove_cert_from_db (const grub_uint8_t *data, const
grub_size_t data_size)
return rc;
}
+static bool
+cert_fingerprint_match (const grub_uint8_t *hash_data, const grub_size_t
hash_data_size,
+ const grub_x509_cert_t *cert)
+{
+ grub_int32_t type;
+
+ if (hash_data_size == SHA256_HASH_LEN)
+ type = GRUB_FINGERPRINT_SHA256;
+ else if (hash_data_size == SHA384_HASH_LEN)
+ type = GRUB_FINGERPRINT_SHA384;
+ else if (hash_data_size == SHA512_HASH_LEN)
+ type = GRUB_FINGERPRINT_SHA512;
+ else
+ {
+ grub_dprintf ("appendedsig", "unsupported fingerprint hash type "
+ "(%" PRIuGRUB_SIZE ") \n", hash_data_size);
+ return false;
+ }
+
+ if (grub_memcmp (cert->fingerprint[type], hash_data, hash_data_size) == 0)
+ return true;
+
+ return false;
+}
+
+static void
+remove_hash_from_db (const grub_uint8_t *hash_data, const grub_size_t
hash_data_size,
+ const bool bin_hash)
+{
+ grub_uint32_t i;
+ grub_x509_cert_t *cert;
+
+ if (bin_hash == true)
+ {
+ for (i = 0; i < db.hash_entries; i++)
+ {
+ if (db.hashes[i] == NULL)
+ continue;
+
+ if (grub_memcmp (db.hashes[i], hash_data, hash_data_size) == 0)
+ {
+ grub_dprintf ("appendedsig", "removed distrusted hash
%02x%02x%02x%02x.. from the db list\n",
+ db.hashes[i][0], db.hashes[i][1], db.hashes[i][2],
db.hashes[i][3]);
+ grub_free (db.hashes[i]);
+ db.hashes[i] = NULL;
+ db.hash_sizes[i] = 0;
+ break;
+ }
+ }
+ }
+ else
+ {
+ for (cert = db.certs; cert != NULL; cert = cert->next)
+ {
+ if (cert_fingerprint_match (hash_data, hash_data_size, cert) == true)
+ {
+ _remove_cert_from_db (cert);
+ break;
+ }
+ }
+ }
+}
+
static grub_err_t
file_read_whole (grub_file_t file, grub_uint8_t **buf, grub_size_t *len)
{
@@ -1020,6 +1093,194 @@ grub_cmd_list_db (grub_command_t cmd __attribute__
((unused)), int argc __attrib
return GRUB_ERR_NONE;
}
+static grub_err_t
+grub_cmd_list_dbx (grub_command_t cmd __attribute__((unused)),
+ int argc __attribute__((unused)), char **args
__attribute__((unused)))
+{
+ struct x509_certificate *cert;
+ grub_uint32_t i, cert_num = 1;
+
+ if (append_key_mgmt == false)
+ return grub_error (GRUB_ERR_ACCESS_DENIED,
+ "append_list_dbx command is unsupported in static key
mode");
+
+ for (cert = dbx.certs; cert != NULL; cert = cert->next, cert_num++)
+ print_certificate (cert, cert_num);
+
+ for (i = 0; i < dbx.hash_entries; i++)
+ {
+ if (dbx.hashes[i] != NULL)
+ {
+ grub_printf ("\nCertificate/Binary hash: %u\n", i + 1);
+ grub_printf (" Hash: sha%" PRIuGRUB_SIZE "\n ",
dbx.hash_sizes[i] * 8);
+ hexdump_colon (dbx.hashes[i], dbx.hash_sizes[i]);
+ }
+ }
+
+ return GRUB_ERR_NONE;
+}
+
+/*
+ * Remove the trusted binary hash from the dbx list if present.
+ * And add them to the db list if it is not already present.
+ * Note:- When signature verification is enabled, this command only accepts
+ * the binary hash file that is signed with an appended signature.
+ * The signature is verified by the appendedsig module. If verification
succeeds,
+ * the binary hash is added to the db list. Otherwise, an error is posted and
+ * the binary hash is not added.
+ * When signature verification is disabled, it accepts the binary hash file
without
+ * an appended signature and adds it to the db list.
+ *
+ * Also, note that the adding of the trusted binary hash using this command
does
+ * not persist across reboots.
+ */
+static grub_err_t
+grub_cmd_db_hash (grub_command_t cmd __attribute__((unused)), int argc,
char**args)
+{
+ grub_err_t rc;
+ grub_file_t hash_file;
+ grub_uint8_t *hash_data = NULL;
+ grub_size_t hash_data_size = 0;
+
+ if (append_key_mgmt == false)
+ return grub_error (GRUB_ERR_ACCESS_DENIED,
+ "append_add_db_hash command is unsupported in static
key mode");
+
+ if (argc != 1)
+ return grub_error (GRUB_ERR_BAD_ARGUMENT,
+ "a trusted binary hash file is expected in Binary
format (.bin)\n"
+ "Example:\n\tappend_add_db_hash <BINARY HASH FILE>\n");
+
+ if (!grub_strlen (args[0]))
+ return grub_error (GRUB_ERR_BAD_FILENAME, "missing trusted binary hash
file");
+
+ hash_file = grub_file_open (args[0], GRUB_FILE_TYPE_HASH_TRUST |
GRUB_FILE_TYPE_NO_DECOMPRESS);
+ if (hash_file == NULL)
+ return grub_error (GRUB_ERR_FILE_NOT_FOUND, "unable to open %s file",
args[0]);
+
+ rc = file_read_whole (hash_file, &hash_data, &hash_data_size);
+ grub_file_close (hash_file);
+ if (rc != GRUB_ERR_NONE)
+ return rc;
+
+ /*
+ * If signature verification is enabled,
+ * obtain the actual hash data size by subtracting the appended
+ * signature size from the hash data size because
+ * the hash has an appended signature, and this actual hash data size is
+ * used to get the hash data.
+ */
+ if (check_sigs == true)
+ hash_data_size -= append_sig_len;
+
+ grub_dprintf ("appendedsig",
+ "adding a trusted binary hash %02x%02x%02x%02x...\n with size
of %" PRIuGRUB_SIZE "\n",
+ hash_data[0], hash_data[1], hash_data[2], hash_data[3],
hash_data_size);
+
+ /* Only accept SHA256, SHA384 and SHA512 binary hash */
+ if (hash_data_size != SHA256_HASH_LEN && hash_data_size != SHA384_HASH_LEN &&
+ hash_data_size != SHA512_HASH_LEN)
+ {
+ grub_free (hash_data);
+ return grub_error (GRUB_ERR_BAD_SIGNATURE, "unacceptable trusted binary
hash type");
+ }
+
+ rc = add_hash (hash_data, hash_data_size, &db);
+
+ grub_free (hash_data);
+
+ return rc;
+}
+
+/*
+ * Remove the distrusted binary/certificate hash from the db list if present.
+ * And add them to the dbx list if it is not already present.
+ * Note:- When signature verification is enabled, this command only accepts
+ * the binary/certificate hash file that is signed with an appended signature.
+ * The signature is verified by the appendedsig module. If verification
succeeds,
+ * the binary/certificate hash is added to the dbx list. Otherwise, an error
is posted and
+ * the binary/certificate hash is not added.
+ * When signature verification is disabled, it accepts the binary/certificate
hash file without
+ * an appended signature and adds it to the dbx list.
+ *
+ * Also, note that the adding of the distrusted binary/certificate hash using
this command does
+ * not persist across reboots.
+ */
+static grub_err_t
+grub_cmd_dbx_hash (grub_extcmd_context_t ctxt, int argc __attribute__
((unused)),
+ char **args __attribute__ ((unused)))
+{
+ grub_err_t rc;
+ grub_file_t hash_file;
+ grub_uint8_t *hash_data = NULL;
+ grub_size_t hash_data_size = 0;
+ char *file_path;
+
+ if (append_key_mgmt == false)
+ return grub_error (GRUB_ERR_ACCESS_DENIED,
+ "append_add_dbx_hash command is unsupported in static
key mode");
+
+ if (!ctxt->state[OPTION_BINARY_HASH].set &&
!ctxt->state[OPTION_CERT_HASH].set)
+ return grub_error (GRUB_ERR_BAD_ARGUMENT,
+ "a distrusted certificate/binary hash file is expected
in Binary format (.bin)\n"
+ "Example:\n\tappend_add_dbx_hash [option] <FILE>\n"
+ "option:\n[-b|--binary-hash] FILE [BINARY HASH FILE]\n"
+ "[-c|--cert-hash] FILE [CERTFICATE HASH FILE]\n");
+
+ if (ctxt->state[OPTION_BINARY_HASH].arg == NULL &&
ctxt->state[OPTION_CERT_HASH].arg == NULL)
+ return grub_error (GRUB_ERR_BAD_FILENAME, "missing distrusted
certificate/binary hash file");
+
+ if (ctxt->state[OPTION_BINARY_HASH].arg != NULL)
+ file_path = ctxt->state[OPTION_BINARY_HASH].arg;
+ else
+ file_path = ctxt->state[OPTION_CERT_HASH].arg;
+
+ hash_file = grub_file_open (file_path, GRUB_FILE_TYPE_HASH_TRUST |
GRUB_FILE_TYPE_NO_DECOMPRESS);
+ if (hash_file == NULL)
+ return grub_error (GRUB_ERR_FILE_NOT_FOUND, "unable to open %s file",
file_path);
+
+ rc = file_read_whole (hash_file, &hash_data, &hash_data_size);
+ grub_file_close (hash_file);
+ if (rc != GRUB_ERR_NONE)
+ return rc;
+
+ /*
+ * If signature verification is enabled,
+ * obtain the actual hash data size by subtracting the appended
+ * signature size from the hash data size because
+ * the hash has an appended signature, and this actual hash data size is
+ * used to get the hash data.
+ */
+ if (check_sigs == true)
+ hash_data_size -= append_sig_len;
+
+ grub_dprintf ("appendedsig",
+ "adding a distrusted certificate/binary hash
%02x%02x%02x%02x...\n"
+ " with size of %" PRIuGRUB_SIZE "\n", hash_data[0],
hash_data[1],
+ hash_data[2], hash_data[3], hash_data_size);
+
+ if (ctxt->state[OPTION_BINARY_HASH].set || ctxt->state[OPTION_CERT_HASH].set)
+ {
+ /* Only accept SHA256, SHA384 and SHA512 certificate/binary hash */
+ if (hash_data_size != SHA256_HASH_LEN && hash_data_size !=
SHA384_HASH_LEN &&
+ hash_data_size != SHA512_HASH_LEN)
+ {
+ grub_free (hash_data);
+ return grub_error (GRUB_ERR_BAD_SIGNATURE,
+ "unacceptable distrusted certificate/binary hash
type");
+ }
+ }
+
+ /* Remove distrusted binary hash/certificate from the db list if present. */
+ remove_hash_from_db (hash_data, hash_data_size,
+ ((ctxt->state[OPTION_BINARY_HASH].set) ? true : false));
+ rc = add_hash (hash_data, hash_data_size, &dbx);
+
+ grub_free (hash_data);
+
+ return rc;
+}
+
/* Add the X.509 certificates/binary hash to the db list from PKS. */
static grub_err_t
load_pks2db (void)
@@ -1344,6 +1605,8 @@ struct grub_file_verifier grub_appendedsig_verifier = {
};
static grub_command_t cmd_verify, cmd_list_db, cmd_dbx_cert, cmd_db_cert;
+static grub_command_t cmd_list_dbx, cmd_db_hash;
+static grub_extcmd_t cmd_dbx_hash;
GRUB_MOD_INIT (appendedsig)
{
@@ -1422,6 +1685,16 @@ GRUB_MOD_INIT (appendedsig)
cmd_dbx_cert = grub_register_command ("append_add_dbx_cert",
grub_cmd_dbx_cert, N_("<X509_CERTIFICATE>"),
N_("Add distrusted X509_CERTIFICATE to
the dbx list"));
+ cmd_list_dbx = grub_register_command ("append_list_dbx", grub_cmd_list_dbx,
0,
+ N_("Show the list of distrusted
certificates and"
+ " certificate/binary hashes from the
dbx list"));
+ cmd_db_hash = grub_register_command ("append_add_db_hash", grub_cmd_db_hash,
N_("BINARY HASH FILE"),
+ N_("Add trusted BINARY HASH to the db
list."));
+ cmd_dbx_hash = grub_register_extcmd ("append_add_dbx_hash",
grub_cmd_dbx_hash, 0,
+ N_("[-b|--binary-hash] FILE [BINARY
HASH FILE]\n"
+ "[-c|--cert-hash] FILE [CERTFICATE HASH
FILE]"),
+ N_("Add distrusted CERTFICATE/BINARY
HASH to the dbx list."), options);
+
grub_verifier_register (&grub_appendedsig_verifier);
grub_dl_set_persistent (mod);
}
@@ -1444,4 +1717,7 @@ GRUB_MOD_FINI (appendedsig)
grub_unregister_command (cmd_list_db);
grub_unregister_command (cmd_db_cert);
grub_unregister_command (cmd_dbx_cert);
+ grub_unregister_command (cmd_list_dbx);
+ grub_unregister_command (cmd_db_hash);
+ grub_unregister_extcmd (cmd_dbx_hash);
}
diff --git a/include/grub/file.h b/include/grub/file.h
index d678de063..16a4b7d26 100644
--- a/include/grub/file.h
+++ b/include/grub/file.h
@@ -115,6 +115,8 @@ enum grub_file_type
GRUB_FILE_TYPE_HASHLIST,
/* File hashed by hashsum. */
GRUB_FILE_TYPE_TO_HASH,
+ /* File holding certificiate/binary hash to add to db/dbx. */
+ GRUB_FILE_TYPE_HASH_TRUST,
/* Keyboard layout. */
GRUB_FILE_TYPE_KEYBOARD_LAYOUT,
/* Picture file. */
--
2.39.5 (Apple Git-154)
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