On Tue, Jul 29, 2025 at 08:21:52PM +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 properly signed.
> 2. When append_add_db_hash executes, then the binary hash file
> must be properly signed.
> 3. When append_add_dbx_hash executes, then the certificate/binary
> hash file must be signed.
>
> Signed-off-by: Sudhakar Kuppusamy <[email protected]>
> Reviewed-by: Avnish Chouhan <[email protected]>
> ---
> grub-core/commands/appendedsig/appendedsig.c | 377 ++++++++++++++++++-
> include/grub/file.h | 2 +
> 2 files changed, 362 insertions(+), 17 deletions(-)
>
> diff --git a/grub-core/commands/appendedsig/appendedsig.c
> b/grub-core/commands/appendedsig/appendedsig.c
> index fa908b963..1d7dc7ba1 100644
> --- a/grub-core/commands/appendedsig/appendedsig.c
> +++ b/grub-core/commands/appendedsig/appendedsig.c
> @@ -42,6 +42,9 @@ GRUB_MOD_LICENSE ("GPLv3+");
> /* Public key type. */
> #define GRUB_PKEY_ID_PKCS7 2
>
> +#define OPTION_BINARY_HASH 0
> +#define OPTION_CERT_HASH 1
> +
> /* Appended signature magic string. */
> static const char magic[] = "~Module signature appended~\n";
>
> @@ -106,6 +109,13 @@ static grub_size_t append_sig_len = 0;
> */
> static bool check_sigs = false;
>
> +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 const char *
> grub_env_read_sec (struct grub_env_var *var __attribute__ ((unused)),
> const char *val __attribute__ ((unused)))
> @@ -648,8 +658,8 @@ is_cert_present_in_db (const struct x509_certificate
> *cert_in)
> return false;
> }
>
> -static bool
> -is_cert_removed_from_db (const struct x509_certificate *cert)
> +static void
> +remove_cert_from_db (const struct x509_certificate *cert)
This...
> {
> int i = 1;
> struct x509_certificate *curr_cert, *prev_cert;
> @@ -664,17 +674,64 @@ is_cert_removed_from_db (const struct x509_certificate
> *cert)
> prev_cert->next = curr_cert->next;
>
> grub_dprintf ("appendedsig",
> - "removed certificate with CN: %s from the db
> list\n", curr_cert->subject);
> + "removed distrused certificate with CN: %s from the
> db list\n",
> + curr_cert->subject);
... this...
> curr_cert->next = NULL;
> certificate_release (curr_cert);
> grub_free (curr_cert);
> - return true;
> + break;
... and this change does not belong to this patch...
> }
> else
> prev_cert = curr_cert;
>
> i++;
> }
> +}
> +
> +/*
> + * We cannot use hexdump() to display hash data because it is typically
> + * displayed in hexadecimal format, along with an ASCII representation of
> + * the same data.
> + * Example: sha256 hash data
> + * 00000000 52 b5 90 49 64 de 22 d7 4e 5f 4f b4 1b 51 9c 34
> |R..Id.".N_O..Q.4|
> + * 00000010 b1 96 21 7c 91 78 a5 0d 20 8c e9 5c 22 54 53 f7 |..!|.x..
> ..\"TS.|
> + *
> + * An appended signature only required to display the hexadecimal of the
> hash data
> + * by separating each byte with ":". So, we introduced a new method
> dump_ascii_to_hex
> + * to display it.
> + * Example: Sha256 hash data
> + * 52:b5:90:49:64:de:22:d7:4e:5f:4f:b4:1b:51:9c:34:
> + * b1:96:21:7c:91:78:a5:0d:20:8c:e9:5c:22:54:53:f7
> + */
> +static void
> +dump_ascii_to_hex (const grub_uint8_t *data, const grub_size_t length)
s/dump_ascii_to_hex/dump_data_hex/
> +{
> + grub_size_t i, count = 0;
> +
> + for (i = 0; i < length - 1; i++)
> + {
> + grub_printf ("%02x:", data[i]);
> + count++;
> + if (count == 16)
> + {
> + grub_printf ("\n\t ");
> + count = 0;
> + }
> + }
> +
> + grub_printf ("%02x\n", data[i]);
> +}
> +
> +static bool
> +is_cert_present_in_dbx (const struct x509_certificate *cert_in)
> +{
> + struct x509_certificate *cert;
> +
> + for (cert = dbx.certs; cert; cert = cert->next)
> + {
> + if (is_cert_match (cert, cert_in) == true)
> + return true;
> + }
>
> return false;
> }
> @@ -738,12 +795,21 @@ grub_cmd_db_cert (grub_command_t cmd __attribute__
> ((unused)), int argc, char **
> return err;
> }
>
> - if (is_cert_present_in_db (cert) == true)
> + if (is_cert_present_in_dbx (cert) == false)
> + {
> + if (is_cert_present_in_db (cert) == true)
> + err = grub_error (GRUB_ERR_STILL_REFERENCED,
s/GRUB_ERR_STILL_REFERENCED/GRUB_ERR_EXISTS/? And probably in other
similar places too...
> + "could not add trusted certificate, as it is
> present in the db list");
> + }
> + else
> + err = grub_error (GRUB_ERR_STILL_REFERENCED,
s/GRUB_ERR_STILL_REFERENCED/GRUB_ERR_ACCESS_DENIED/? And probably in other
similar places too...
> + "could not add trusted certificate, as it is present
> in the dbx list");
> +
> + if (err != GRUB_ERR_NONE)
> {
> certificate_release (cert);
> grub_free (cert);
> - return grub_error (GRUB_ERR_STILL_REFERENCED,
> - "could not add the certificate, as it is present in
> the db list");
> + return err;
> }
>
> grub_dprintf ("appendedsig", "added certificate with CN: %s\n",
> cert->subject);
> @@ -765,7 +831,7 @@ 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");
> + "Example:\n\tappend_add_dbx_cert
> <X509_CERTIFICATE>\n");
Hmmm... This looks strange for me...
>
> if (*args == NULL)
> return grub_error (GRUB_ERR_BAD_FILENAME, "missing distrusted X.509
> certificate file");
> @@ -780,12 +846,24 @@ grub_cmd_dbx_cert (grub_command_t cmd __attribute__
> ((unused)), int argc, char *
> if (err != GRUB_ERR_NONE)
> grub_free (cert);
>
> - if (is_cert_removed_from_db (cert) == false)
> - err = grub_error (GRUB_ERR_EOF,
> - "not found certificate with CN:%s in the db list",
> cert->subject);
> + if (is_cert_present_in_dbx (cert) == true)
> + {
> + certificate_release (cert);
> + grub_free (cert);
> + return grub_error (GRUB_ERR_STILL_REFERENCED,
> + "could not add distrusted certificate, as it is
> present in the dbx list");
> + }
> +
> + /* remove distrusted certificate from the db list if present. */
s/remove/Remove/
> + remove_cert_from_db (cert);
> +
> + grub_dprintf ("appendedsig", "added distrusted certificate with CN: %s to
> the dbx list\n",
> + cert->subject);
> +
> + cert->next = dbx.certs;
> + dbx.certs = cert;
> + dbx.cert_entries++;
>
> - certificate_release (cert);
> - grub_free (cert);
>
> return err;
> }
> @@ -812,9 +890,255 @@ grub_cmd_list_db (grub_command_t cmd __attribute__
> ((unused)), int argc __attrib
> cert_num++;
> }
>
> + for (i = 0; i < db.signature_entries; i++)
> + {
> + if (db.signatures[i] != NULL)
> + {
> + grub_printf ("Binary hash %" PRIuGRUB_SIZE ":\n", i + 1);
> + grub_printf ("\thash: ");
> + dump_ascii_to_hex (db.signatures[i], db.signature_size[i]);
> + }
> + }
> +
> + 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_size_t i, cert_num = 1;
It seems to me this is defined as grub_size_t due to
dbx.signature_entries being grub_size_t. However, I do not think it
should be larger than grub_uint32_t. So, please change all of this
everywhere to grub_uint32_t...
> + for (cert = dbx.certs; cert; cert = cert->next)
for (cert = dbx.certs; cert; cert = cert->next, cert_num++)
... and you can drop "cert_num++" below...
> + {
> + grub_printf ("Certificate %" PRIuGRUB_SIZE ":\n", cert_num);
> + grub_printf ("\tserial: ");
> +
> + for (i = 0; i < cert->serial_len - 1; i++)
> + grub_printf ("%02x:", cert->serial[i]);
> +
> + grub_printf ("%02x\n", cert->serial[cert->serial_len - 1]);
> + grub_printf ("\tissuer: %s\n", cert->issuer);
> + grub_printf ("\tCN: %s\n\n", cert->subject);
> + cert_num++;
> + }
> +
> + for (i = 0; i < dbx.signature_entries; i++)
> + {
> + if (dbx.signatures[i] != NULL)
> + {
> + grub_printf ("Certificate/Binary hash %" PRIuGRUB_SIZE ":\n", i +
> 1);
> + grub_printf ("\thash: ");
> + dump_ascii_to_hex (dbx.signatures[i], dbx.signature_size[i]);
> + }
> + }
> +
> return GRUB_ERR_NONE;
> }
>
> +static grub_err_t
> +read_hash_from_file (char *file_path, grub_uint8_t **hash_data, grub_size_t
> *hash_data_size)
> +{
> + grub_err_t rc;
> + grub_file_t hash_file;
> +
> + 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 (check_sigs == true)
> + *hash_data_size -= append_sig_len;
Please comment this "if"...
> + return rc;
> +}
> +
> +static bool
> +is_hash_present_in_db (const grub_uint8_t *hash_data, const grub_size_t
> hash_data_size)
> +{
> + int i;
> +
> + for (i = 0; i < db.signature_entries; i++)
> + {
> + if (grub_memcmp (db.signatures[i], hash_data, hash_data_size) == 0)
> + return true;
> + }
You can drop curly braces here...
> + return false;
> +}
> +
> +static bool
> +is_hash_present_in_dbx (const grub_uint8_t *hash_data, const grub_size_t
> hash_data_size)
> +{
> + int i;
> +
> + for (i = 0; i < dbx.signature_entries; i++)
> + {
> + if (grub_memcmp (dbx.signatures[i], hash_data, hash_data_size) == 0)
> + return true;
> + }
Ditto...
> + return false;
> +}
> +
> +static void
> +remove_hash_from_db (const grub_uint8_t *hash_data, const grub_size_t
> hash_data_size)
> +{
> + int i;
> +
> + for (i = 0; i < db.signature_entries; i++)
> + {
> + if (grub_memcmp (db.signatures[i], hash_data, hash_data_size) == 0)
> + {
> + grub_dprintf ("appendedsig", "removed distrusted hash
> %02x%02x%02x%02x.. from the db list\n",
> + db.signatures[i][0], db.signatures[i][1],
> db.signatures[i][2],
> + db.signatures[i][3]);
> + grub_free (db.signatures[i]);
> + db.signatures[i] = NULL;
> + db.signature_size[i] = 0;
> + break;
> + }
Something is off with indention here...
> + }
> +}
> +
> +static grub_err_t
> +grub_cmd_db_hash (grub_command_t cmd __attribute__((unused)), int argc,
> char**args)
> +{
> + grub_err_t rc;
> + 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 (*args == NULL)
> + return grub_error (GRUB_ERR_BAD_FILENAME, "missing trusted binary hash
> file");
> +
> + rc = read_hash_from_file (args[0], &hash_data, &hash_data_size);
> + if (rc == GRUB_ERR_NONE)
> + {
> + 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");
> + }
> +
> + if (is_hash_present_in_dbx (hash_data, hash_data_size) == true)
> + {
> + grub_free (hash_data);
> + return grub_error (GRUB_ERR_STILL_REFERENCED,
> + "could not add trusted binary hash, as it is
> present in the dbx list");
> + }
> +
> + if (is_hash_present_in_db (hash_data, hash_data_size) == false)
> + {
> + rc = add_hash ((const grub_uint8_t **) &hash_data, hash_data_size,
> &db.signatures,
> + &db.signature_size, &db.signature_entries);
> + if (rc != GRUB_ERR_NONE)
> + {
> + free_db_list ();
> + free_dbx_list ();
Again, please do not free partial db/dbx... I think this should not be
done in almost everywhere...
> + rc = grub_error (rc, "adding of trusted binary hash failed");
> + }
> + else
> + grub_dprintf ("appendedsig",
> + "added trusted binary hash %02x%02x%02x%02x...\n
> to the db list\n",
> + hash_data[0], hash_data[1], hash_data[2],
> hash_data[3]);
> + }
> + else
> + rc = grub_error (GRUB_ERR_STILL_REFERENCED,
> + "could not add trusted binary hash, as it is
> present in the db list");
> + }
> +
> + grub_free (hash_data);
> +
> + return rc;
> +}
Daniel
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