src/shared/creds-util.h

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2 #pragma once
   3
   4 #include <inttypes.h>
   5 #include <stdbool.h>
   6 #include <sys/types.h>
   7
   8 #include "sd-id128.h"
   9
  10 #include "fd-util.h"
  11 #include "time-util.h"
  12
  13 #define CREDENTIAL_NAME_MAX FDNAME_MAX
  14
  15 /* Put a size limit on the individual credential */
  16 #define CREDENTIAL_SIZE_MAX (1024U*1024U)
  17
  18 /* Refuse to store more than 1M per service, after all this is unswappable memory. Note that for now we put
  19  * this to the same limit as the per-credential limit, i.e. if the user has n > 1 credentials instead of 1 it
  20  * won't get them more space. */
  21 #define CREDENTIALS_TOTAL_SIZE_MAX CREDENTIAL_SIZE_MAX
  22
  23 /* Put a size limit on encrypted credentials (which is the same as the unencrypted size plus a spacious 128K of extra
  24  * space for headers, IVs, exported TPM2 key material and so on. */
  25 #define CREDENTIAL_ENCRYPTED_SIZE_MAX (CREDENTIAL_SIZE_MAX + 128U*1024U)
  26
  27 bool credential_name_valid(const char *s);
  28
  29 /* Where creds have been passed to the local execution context */
  30 int get_credentials_dir(const char **ret);
  31 int get_encrypted_credentials_dir(const char **ret);
  32
  33 /* Where creds have been passed to the system */
  34 #define SYSTEM_CREDENTIALS_DIRECTORY "/run/credentials/@system"
  35 #define ENCRYPTED_SYSTEM_CREDENTIALS_DIRECTORY "/run/credentials/@encrypted"
  36
  37 int read_credential(const char *name, void **ret, size_t *ret_size);
  38
  39 typedef enum CredentialSecretFlags {
  40         CREDENTIAL_SECRET_GENERATE             = 1 << 0,
  41         CREDENTIAL_SECRET_WARN_NOT_ENCRYPTED   = 1 << 1,
  42         CREDENTIAL_SECRET_FAIL_ON_TEMPORARY_FS = 1 << 2,
  43 } CredentialSecretFlags;
  44
  45 int get_credential_host_secret(CredentialSecretFlags flags, void **ret, size_t *ret_size);
  46
  47 int get_credential_user_password(const char *username, char **ret_password, bool *ret_is_hashed);
  48
  49 /* The four modes we support: keyed only by on-disk key, only by TPM2 HMAC key, and by the combination of
  50  * both, as well as one with a fixed zero length key if TPM2 is missing (the latter of course provides no
  51  * authenticity or confidentiality, but is still useful for integrity protection, and makes things simpler
  52  * for us to handle). */
  53 #define CRED_AES256_GCM_BY_HOST               SD_ID128_MAKE(5a,1c,6a,86,df,9d,40,96,b1,d5,a6,5e,08,62,f1,9a)
  54 #define CRED_AES256_GCM_BY_TPM2_HMAC          SD_ID128_MAKE(0c,7c,c0,7b,11,76,45,91,9c,4b,0b,ea,08,bc,20,fe)
  55 #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)
  56 #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)
  57
  58 /* Two special IDs to pick a general automatic mode (i.e. tpm2+host if TPM2 exists, only host otherwise) or
  59  * an initrd-specific automatic mode (i.e. tpm2 if firmware can do it, otherwise fixed zero-length key, and
  60  * never involve host keys). These IDs will never be stored on disk, but are useful only internally while
  61  * figuring out what precisely to write to disk. To mark that these aren't a "real" type, we'll prefix them
  62  * with an underscore. */
  63 #define _CRED_AUTO                            SD_ID128_MAKE(a2,19,cb,07,85,b2,4c,04,b1,6d,18,ca,b9,d2,ee,01)
  64 #define _CRED_AUTO_INITRD                     SD_ID128_MAKE(02,dc,8e,de,3a,02,43,ab,a9,ec,54,9c,05,e6,a0,71)
  65
  66 int encrypt_credential_and_warn(sd_id128_t with_key, const char *name, usec_t timestamp, usec_t not_after, const char *tpm2_device, uint32_t tpm2_pcr_mask, const void *input, size_t input_size, void **ret, size_t *ret_size);
  67 int decrypt_credential_and_warn(const char *validate_name, usec_t validate_timestamp, const char *tpm2_device, const void *input, size_t input_size, void **ret, size_t *ret_size);