On Mon, Aug 25, 2025 at 04:38:39PM +0530, Sudhakar Kuppusamy wrote:
> Introducing the following db and dbx commands
>
> 1. append_list_db:
> Show the list of trusted certificates and binary hashes
> from the db list.
> 2. append_list_dbx:
> Show the list of distrusted certificates and binary/certificate
> hashes from the dbx list.
> 3. append_add_db_cert:
> Add the trusted certificate to the db list.
> 4. append_add_db_hash:
> Add the trusted binary hash to the db list.
> 5. append_add_dbx_cert:
> Add the distrusted certificate to the dbx list.
> 6. 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,
> 1. When append_add_db_cert or append_add_dbx_cert executes,
> then the certificate file must be signed with an appended signature.
> 2. When append_add_db_hash executes, then the binary hash file
> must be signed with an appended signature.
> 3. When append_add_dbx_hash executes, then the certificate/binary
> hash file must be signed with an appended signature.
>
> Signed-off-by: Sudhakar Kuppusamy <sudha...@linux.ibm.com>
> Reviewed-by: Avnish Chouhan <avn...@linux.ibm.com>
> ---
> grub-core/commands/appendedsig/appendedsig.c | 319 ++++++++++++++++++-
> include/grub/file.h | 2 +
> 2 files changed, 312 insertions(+), 9 deletions(-)
>
> diff --git a/grub-core/commands/appendedsig/appendedsig.c
> b/grub-core/commands/appendedsig/appendedsig.c
> index 5da603eb6..ea1937a7e 100644
> --- a/grub-core/commands/appendedsig/appendedsig.c
> +++ b/grub-core/commands/appendedsig/appendedsig.c
> @@ -49,6 +49,9 @@ GRUB_MOD_LICENSE ("GPLv3+");
> #define SIG_MAGIC "~Module signature appended~\n"
> #define SIG_MAGIC_SIZE ((sizeof(SIG_MAGIC) - 1))
>
> +#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.
> @@ -110,6 +113,13 @@ static bool check_sigs = false;
> /* 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 void
> register_appended_signatures_cmd (void);
> static void
> @@ -593,6 +603,53 @@ remove_cert_from_db (const grub_uint8_t *data, const
> grub_size_t data_size)
> return rc;
> }
>
> +static bool
> +is_cert_fingerprint_match (const grub_uint8_t *hash_data, const grub_size_t
> hash_data_size,
> + const struct x509_certificate *cert)
s/is_cert_fingerprint_match/cert_fingerprint_match/
> +{
> + if (grub_memcmp (cert->fingerprint[0], hash_data, hash_data_size) == 0
> + || grub_memcmp (cert->fingerprint[1], hash_data, hash_data_size) == 0
> + || grub_memcmp (cert->fingerprint[2], hash_data, hash_data_size) == 0)
Why are you comparing all hashes instead of chosen one?
> + 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 is_binary_hash)
s/is_binary_hash/bin_hash/
> +{
> + grub_uint32_t i;
> + struct x509_certificate *cert;
> +
> + if (is_binary_hash == true)
> + {
> + for (i = 0; i < db.hash_entries; i++)
> + {
> + 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_size[i] = 0;
> + break;
> + }
> + }
> + }
> + else
> + {
> + for (cert = db.certs; cert != NULL; cert = cert->next)
> + {
> + if (is_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)
> {
> @@ -913,6 +970,8 @@ grub_cmd_verify_signature (grub_command_t cmd
> __attribute__ ((unused)), int argc
>
> /*
> * Add the trusted certificate to the db list if it is not already present.
> + * Checks the trusted certificate against dbx list if dynamic key management
> is enabled.
> + * And add it to the db list if it is not already present.
> * Note:- When signature verification is enabled, this command only accepts
> the
> * trusted certificate that is signed with an appended signature.
> * The signature is verified by the appendedsig module. If verification
> succeeds,
> @@ -970,6 +1029,8 @@ grub_cmd_db_cert (grub_command_t cmd __attribute__
> ((unused)), int argc, char **
>
> /*
> * Remove the distrusted certificate from the db list if it is already
> present.
> + * And add it to the dbx list if not present when dynamic key management is
> + * enabled.
> * Note:- When signature verification is enabled, this command only accepts
> the
> * distrusted certificate that is signed with an appended signature.
> * The signature is verified by the appended sig module. If verification
> succeeds,
> @@ -979,7 +1040,9 @@ grub_cmd_db_cert (grub_command_t cmd __attribute__
> ((unused)), int argc, char **
> * without an appended signature and removes it from the db list.
> *
> * Also, note that the removal of the distrusted certificate using this
> command
> - * does not persist across reboots.
> + * does not persist across reboots. If static key management is enabled, the
> + * append_rm_dbx_cert command is only available in the GRUB console. Else the
> + * append_add_dbx_cert command is available in the GRUB console.
> */
> static grub_err_t
> grub_cmd_dbx_cert (grub_command_t cmd __attribute__ ((unused)), int argc,
> char **args)
> @@ -991,8 +1054,10 @@ grub_cmd_dbx_cert (grub_command_t cmd __attribute__
> ((unused)), int argc, char *
>
> if (argc != 1)
> return grub_error (GRUB_ERR_BAD_ARGUMENT,
> - "a distrusted X.509 certificate file is expected in
> DER format\n"
> - "Example:\n\tappend_rm_dbx_cert
> <X509_CERTIFICATE>\n");
> + "a distrusted X.509 certificate file is expected in
> DER format\n%s",
> + ((grub_pks_keystore.use_keystore == true) ?
> + "Example:\n\tappend_add_dbx_cert
> <X509_CERTIFICATE>\n" :
> + "Example:\n\tappend_rm_dbx_cert
> <X509_CERTIFICATE>\n"));
>
> if (!grub_strlen (args[0]))
> return grub_error (GRUB_ERR_BAD_FILENAME, "missing distrusted X.509
> certificate file");
> @@ -1019,9 +1084,21 @@ grub_cmd_dbx_cert (grub_command_t cmd __attribute__
> ((unused)), int argc, char *
>
> /* Remove distrusted certificate from the db list if present. */
> err = remove_cert_from_db (cert_data, cert_data_size);
> - grub_free (cert_data);
> if (err != GRUB_ERR_NONE)
> - return err;
> + {
> + grub_free (cert_data);
> + return err;
> + }
> +
> + /* Only add the certificate to the dbx list if dynamic key management is
> enabled. */
> + if (grub_pks_keystore.use_keystore == true)
> + {
> + err = add_certificate (cert_data, cert_data_size, &dbx, false);
> + if (err != GRUB_ERR_NONE)
> + return err;
> + }
> +
> + grub_free (cert_data);
>
> return GRUB_ERR_NONE;
> }
> @@ -1036,9 +1113,196 @@ grub_cmd_list_db (grub_command_t cmd __attribute__
> ((unused)), int argc __attrib
> for (cert = db.certs; cert != NULL; cert = cert->next, cert_num++)
> print_certificate (cert, cert_num);
>
> + /* Only list the binary hash if dynamic key management is enabled. */
Why?
> + if (grub_pks_keystore.use_keystore == true)
> + {
> + for (i = 0; i < db.hash_entries; i++)
> + {
> + if (db.hashes[i] != NULL)
> + {
> + grub_printf ("\nBinary hash: %u\n", i + 1);
> + grub_printf (" Hash: sha%" PRIuGRUB_SIZE "\n ",
> db.hash_size[i] * 8);
> + dump_data_to_hex (db.hashes[i], db.hash_size[i]);
> + }
> + }
> + }
This change does not seem to belong to this patch...
> +
> 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;
> +
> + 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_size[i] * 8);
> + dump_data_to_hex (dbx.hashes[i], dbx.hash_size[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 (argc != 1)
> + return grub_error (GRUB_ERR_BAD_ARGUMENT,
> + "a trusted binary hash file is expected in ASCII text
> format\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 and GRUB is locked down,
> + * 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 && grub_is_lockdown () == GRUB_LOCKDOWN_ENABLED)
> + 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 != 32 && hash_data_size != 48 && hash_data_size != 64)
> + {
> + 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, true);
> + 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 (!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 ASCII text format\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 and GRUB is locked down,
> + * 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 && grub_is_lockdown () == GRUB_LOCKDOWN_ENABLED)
> + 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 != 32 && hash_data_size != 48 && hash_data_size !=
> 64)
> + {
> + 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, false);
> + grub_free (hash_data);
> +
> + return rc;
> +}
> +
> /* Add the X.509 certificates/binary hash to the db list from PKS. */
> static grub_err_t
> create_db_list (void)
> @@ -1297,10 +1561,16 @@ grub_env_write_key_mgmt (struct grub_env_var *var
> __attribute__ ((unused)), cons
> if (grub_pks_keystore.pks_supported == true &&
> grub_pks_keystore.use_keystore == false)
> build_pks_keystore ();
>
> + unregister_appended_signatures_cmd ();
> grub_pks_keystore.use_keystore = true;
> + register_appended_signatures_cmd ();
> }
> else if ((*val == '0') || (*val == 's'))
> - grub_pks_keystore.use_keystore = false;
> + {
> + unregister_appended_signatures_cmd ();
> + grub_pks_keystore.use_keystore = false;
> + register_appended_signatures_cmd ();
> + }
>
> ret = grub_strdup (grub_env_read_key_mgmt (NULL, NULL));
> if (ret == NULL)
> @@ -1369,7 +1639,9 @@ struct grub_file_verifier grub_appendedsig_verifier = {
> .write = appendedsig_write,
> };
>
> -static grub_command_t cmd_verify, cmd_list_db, cmd_dbx_cert, cmd_db_cert;
> +static grub_extcmd_t cmd_dbx_hash;
> +static grub_command_t cmd_verify, cmd_list_db, cmd_db_cert, cmd_db_hash,
> + cmd_list_dbx, cmd_dbx_cert;
>
> /* It registers the appended signatures GRUB commands. */
> static void
> @@ -1381,8 +1653,27 @@ register_appended_signatures_cmd (void)
> N_("Show the list of trusted X.509
> certificates from the db list"));
> cmd_db_cert = grub_register_command ("append_add_db_cert",
> grub_cmd_db_cert, N_("X509_CERTIFICATE"),
> N_("Add trusted X509_CERTIFICATE to
> the db list"));
> - cmd_dbx_cert = grub_register_command ("append_rm_dbx_cert",
> grub_cmd_dbx_cert, N_("X509_CERTIFICATE"),
> - N_("Remove distrusted
> X509_CERTIFICATE from the db list"));
> + /*
> + * If signature verification is enabled with dynamic key management mode,
> + * register dynamic secure boot GRUB commands.
> + */
> + if (grub_pks_keystore.use_keystore == true)
> + {
> + 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);
> + }
> + else
> + cmd_dbx_cert = grub_register_command ("append_rm_dbx_cert",
> grub_cmd_dbx_cert, N_("X509_CERTIFICATE"),
> + N_("Remove distrusted
> X509_CERTIFICATE from the db list"));
> }
>
> /* It unregisters the appended signatures GRUB commands. */
> @@ -1393,6 +1684,16 @@ unregister_appended_signatures_cmd (void)
> grub_unregister_command (cmd_list_db);
> grub_unregister_command (cmd_db_cert);
> grub_unregister_command (cmd_dbx_cert);
> + /*
> + * If signature verification is enabled with dynamic key management mode,
> + * unregister dynamic secure boot GRUB commands.
Why? I think these commands should be always enabled and do not print
anything if relevant databases are empty. It is also worth considering
a command which would print state of PKS and static keys.
> + */
> + if (grub_pks_keystore.use_keystore == true)
> + {
> + grub_unregister_command (cmd_list_dbx);
> + grub_unregister_command (cmd_db_hash);
> + grub_unregister_extcmd (cmd_dbx_hash);
> + }
> }
Daniel
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