creds: rename "tpm2-absent" encryption to "null" encryption

This is what it is after all: encryption with a NULL key. This is more
descriptive, but also relevant since we want to use this kind of
credentials in a different context soon: for carrying pcrlock data into
a UKI. In that case we don#t want encryption, since the pcrlock data is
intended to help unlocking secrets, hence should not be a secret itself.

This only changes the code labels and the way this is labelled in the
output. We retain compat with the old name.

diff --git a/man/systemd-creds.xml b/man/systemd-creds.xml
index 60f38f6bd997263bf93a9f3299a43734017ba8e5..5f52540e84e8728a0dd73ed470e2f0b1186f1e67 100644 (file)
--- a/man/systemd-creds.xml
+++ b/man/systemd-creds.xml
@@ -310,7 +310,7 @@
 
         <listitem><para>When specified with the <command>encrypt</command> command controls the
         encryption/signature key to use. Takes one of <literal>host</literal>, <literal>tpm2</literal>,
-        <literal>host+tpm2</literal>, <literal>tpm2-absent</literal>, <literal>auto</literal>,
+        <literal>host+tpm2</literal>, <literal>null</literal>, <literal>auto</literal>,
         <literal>auto-initrd</literal>. See above for details on the three key types. If set to
         <literal>auto</literal> (which is the default) the TPM2 key is used if a TPM2 device is found and not
         running in a container. The host key is used if <filename>/var/lib/systemd/</filename> is on
@@ -318,13 +318,13 @@
         chip and the OS installation, and both need to be available to decrypt the credential again. If
         <literal>auto</literal> is selected but neither TPM2 is available (or running in container) nor
         <filename>/var/lib/systemd/</filename> is on persistent media, encryption will fail. If set to
-        <literal>tpm2-absent</literal> a fixed zero length key is used (thus, in this mode no confidentiality
+        <literal>null</literal> a fixed zero length key is used (thus, in this mode no confidentiality
         nor authenticity are provided!). This logic is useful to cover for systems that lack a TPM2 chip but
         where credentials shall be generated. Note that decryption of such credentials is refused on systems
         that have a TPM2 chip and where UEFI SecureBoot is enabled (this is done so that such a locked down
         system cannot be tricked into loading a credential generated this way that lacks authentication
         information). If set to <literal>auto-initrd</literal> a TPM2 key is used if a TPM2 is found. If not
-        a fixed zero length key is used, equivalent to <literal>tpm2-absent</literal> mode. This option is
+        a fixed zero length key is used, equivalent to <literal>null</literal> mode. This option is
         particularly useful to generate credentials files that are encrypted/authenticated against TPM2 where
         available but still work on systems lacking support for this.</para>
 

diff --git a/src/creds/creds.c b/src/creds/creds.c
index 5586baff9a49c882318fa668828e6194fb0462c8..f84eee292bec178d80e9191f964dbd17ad88c678 100644 (file)
--- a/src/creds/creds.c
+++ b/src/creds/creds.c
@@ -843,8 +843,8 @@ static int parse_argv(int argc, char *argv[]) {
                                 arg_with_key = CRED_AES256_GCM_BY_HOST_AND_TPM2_HMAC;
                         else if (STR_IN_SET(optarg, "host+tpm2-with-public-key", "tpm2-with-public-key+host"))
                                 arg_with_key = CRED_AES256_GCM_BY_HOST_AND_TPM2_HMAC_WITH_PK;
-                        else if (streq(optarg, "tpm2-absent"))
-                                arg_with_key = CRED_AES256_GCM_BY_TPM2_ABSENT;
+                        else if (STR_IN_SET(optarg, "null", "tpm2-absent"))
+                                arg_with_key = CRED_AES256_GCM_BY_NULL;
                         else
                                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Unknown key type: %s", optarg);
 

diff --git a/src/shared/creds-util.c b/src/shared/creds-util.c
index 0026da5b48352fcabc7ebd73caeb0245989fad5a..1c12fdfa9fad7e1980b42e78ab02384f08d73a61 100644 (file)
--- a/src/shared/creds-util.c
+++ b/src/shared/creds-util.c
@@ -760,7 +760,7 @@ int encrypt_credential_and_warn(
                              CRED_AES256_GCM_BY_TPM2_HMAC_WITH_PK,
                              CRED_AES256_GCM_BY_HOST_AND_TPM2_HMAC,
                              CRED_AES256_GCM_BY_HOST_AND_TPM2_HMAC_WITH_PK,
-                             CRED_AES256_GCM_BY_TPM2_ABSENT))
+                             CRED_AES256_GCM_BY_NULL))
                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Invalid key type: " SD_ID128_FORMAT_STR, SD_ID128_FORMAT_VAL(with_key));
 
         if (name && !credential_name_valid(name))
@@ -911,14 +911,14 @@ int encrypt_credential_and_warn(
                 else if (host_key)
                         id = CRED_AES256_GCM_BY_HOST;
                 else if (sd_id128_equal(with_key, _CRED_AUTO_INITRD))
-                        id = CRED_AES256_GCM_BY_TPM2_ABSENT;
+                        id = CRED_AES256_GCM_BY_NULL;
                 else
                         return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE),
                                                "TPM2 not available and host key located on temporary file system, no encryption key available.");
         } else
                 id = with_key;
 
-        if (sd_id128_equal(id, CRED_AES256_GCM_BY_TPM2_ABSENT))
+        if (sd_id128_equal(id, CRED_AES256_GCM_BY_NULL))
                 log_warning("Using a null key for encryption and signing. Confidentiality or authenticity will not be provided.");
 
         /* Let's now take the host key and the TPM2 key and hash it together, to use as encryption key for the data */
@@ -1092,7 +1092,7 @@ int decrypt_credential_and_warn(
         struct encrypted_credential_header *h;
         struct metadata_credential_header *m;
         uint8_t md[SHA256_DIGEST_LENGTH];
-        bool with_tpm2, with_host_key, is_tpm2_absent, with_tpm2_pk;
+        bool with_tpm2, with_tpm2_pk, with_host_key, with_null;
         const EVP_CIPHER *cc;
         int r, added;
 
@@ -1109,9 +1109,9 @@ int decrypt_credential_and_warn(
         with_host_key = sd_id128_in_set(h->id, CRED_AES256_GCM_BY_HOST, CRED_AES256_GCM_BY_HOST_AND_TPM2_HMAC, CRED_AES256_GCM_BY_HOST_AND_TPM2_HMAC_WITH_PK);
         with_tpm2_pk = sd_id128_in_set(h->id, CRED_AES256_GCM_BY_TPM2_HMAC_WITH_PK, CRED_AES256_GCM_BY_HOST_AND_TPM2_HMAC_WITH_PK);
         with_tpm2 = sd_id128_in_set(h->id, CRED_AES256_GCM_BY_TPM2_HMAC, CRED_AES256_GCM_BY_HOST_AND_TPM2_HMAC) || with_tpm2_pk;
-        is_tpm2_absent = sd_id128_equal(h->id, CRED_AES256_GCM_BY_TPM2_ABSENT);
+        with_null = sd_id128_equal(h->id, CRED_AES256_GCM_BY_NULL);
 
-        if (!with_host_key && !with_tpm2 && !is_tpm2_absent)
+        if (!with_host_key && !with_tpm2 && !with_null)
                 return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "Unknown encryption format, or corrupted data: %m");
 
         if (with_tpm2_pk) {
@@ -1120,7 +1120,7 @@ int decrypt_credential_and_warn(
                         return log_error_errno(r, "Failed to load pcr signature: %m");
         }
 
-        if (is_tpm2_absent) {
+        if (with_null) {
                 /* So this is a credential encrypted with a zero length key. We support this to cover for the
                  * case where neither a host key not a TPM2 are available (specifically: initrd environments
                  * where the host key is not yet accessible and no TPM2 chip exists at all), to minimize
@@ -1257,7 +1257,7 @@ int decrypt_credential_and_warn(
                         return log_error_errno(r, "Failed to determine local credential key: %m");
         }
 
-        if (is_tpm2_absent)
+        if (with_null)
                 log_warning("Warning: using a null key for decryption and authentication. Confidentiality or authenticity are not provided.");
 
         sha256_hash_host_and_tpm2_key(host_key, host_key_size, tpm2_key, tpm2_key_size, md);

diff --git a/src/shared/creds-util.h b/src/shared/creds-util.h
index 36ca0fb61009a8b18e559267d12a900c5b228c72..b34dba7cc2fc5c2fadd18fbef86060c7cf62ba04 100644 (file)
--- a/src/shared/creds-util.h
+++ b/src/shared/creds-util.h
@@ -67,7 +67,7 @@ int get_credential_user_password(const char *username, char **ret_password, bool
 #define CRED_AES256_GCM_BY_HOST_AND_TPM2_HMAC SD_ID128_MAKE(93,a8,94,09,48,74,44,90,90,ca,f2,fc,93,ca,b5,53)
 #define CRED_AES256_GCM_BY_HOST_AND_TPM2_HMAC_WITH_PK           \
                                               SD_ID128_MAKE(af,49,50,a8,49,13,4e,b1,a7,38,46,30,4f,f3,0c,05)
-#define CRED_AES256_GCM_BY_TPM2_ABSENT        SD_ID128_MAKE(05,84,69,da,f6,f5,43,24,80,05,49,da,0f,8e,a2,fb)
+#define CRED_AES256_GCM_BY_NULL               SD_ID128_MAKE(05,84,69,da,f6,f5,43,24,80,05,49,da,0f,8e,a2,fb)
 
 /* Two special IDs to pick a general automatic mode (i.e. tpm2+host if TPM2 exists, only host otherwise) or
  * an initrd-specific automatic mode (i.e. tpm2 if firmware can do it, otherwise fixed zero-length key, and