/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include #if HAVE_OPENSSL #include #endif #include "sd-id128.h" #include "blockdev-util.h" #include "capability-util.h" #include "chattr-util.h" #include "constants.h" #include "creds-util.h" #include "efi-api.h" #include "env-util.h" #include "fd-util.h" #include "fileio.h" #include "fs-util.h" #include "io-util.h" #include "memory-util.h" #include "mkdir.h" #include "openssl-util.h" #include "parse-util.h" #include "path-util.h" #include "random-util.h" #include "sparse-endian.h" #include "stat-util.h" #include "tpm2-util.h" #include "virt.h" #define PUBLIC_KEY_MAX (UINT32_C(1024) * UINT32_C(1024)) bool credential_name_valid(const char *s) { /* We want that credential names are both valid in filenames (since that's our primary way to pass * them around) and as fdnames (which is how we might want to pass them around eventually) */ return filename_is_valid(s) && fdname_is_valid(s); } bool credential_glob_valid(const char *s) { const char *e, *a; size_t n; /* Checks if a credential glob expression is valid. Note that this is more restrictive than * fnmatch()! We only allow trailing asterisk matches for now (simply because we want some freedom * with automatically extending the pattern in a systematic way to cover for unit instances getting * per-instance credentials or similar. Moreover, credential globbing expressions are also more * restrictive then credential names: we don't allow *, ?, [, ] in them (except for the asterisk * match at the end of the string), simply to not allow ambiguity. After all, we want the flexibility * to one day add full globbing should the need arise. */ if (isempty(s)) return false; /* Find first glob (or NUL byte) */ n = strcspn(s, "*?[]"); e = s + n; /* For now, only allow asterisk wildcards, and only at the end of the string. If it's anything else, refuse. */ if (isempty(e)) return credential_name_valid(s); if (!streq(e, "*")) /* only allow trailing "*", no other globs */ return false; if (n == 0) /* Explicitly allow the complete wildcard. */ return true; if (n > NAME_MAX + strlen(e)) /* before we make a copy on the stack, let's check this is not overly large */ return false; /* Make a copy of the string without the '*' suffix */ a = strndupa_safe(s, n); return credential_name_valid(a); } static int get_credentials_dir_internal(const char *envvar, const char **ret) { const char *e; assert(ret); e = secure_getenv(envvar); if (!e) return -ENXIO; if (!path_is_absolute(e) || !path_is_normalized(e)) return -EINVAL; *ret = e; return 0; } int get_credentials_dir(const char **ret) { return get_credentials_dir_internal("CREDENTIALS_DIRECTORY", ret); } int get_encrypted_credentials_dir(const char **ret) { return get_credentials_dir_internal("ENCRYPTED_CREDENTIALS_DIRECTORY", ret); } int read_credential(const char *name, void **ret, size_t *ret_size) { _cleanup_free_ char *fn = NULL; const char *d; int r; assert(ret); if (!credential_name_valid(name)) return -EINVAL; r = get_credentials_dir(&d); if (r < 0) return r; fn = path_join(d, name); if (!fn) return -ENOMEM; return read_full_file_full( AT_FDCWD, fn, UINT64_MAX, SIZE_MAX, READ_FULL_FILE_SECURE, NULL, (char**) ret, ret_size); } int read_credential_with_decryption(const char *name, void **ret, size_t *ret_size) { _cleanup_(erase_and_freep) void *data = NULL; _cleanup_free_ char *fn = NULL; size_t sz = 0; const char *d; int r; assert(ret); /* Just like read_credential() but will also look for encrypted credentials. Note that services only * receive decrypted credentials, hence use read_credential() for those. This helper here is for * generators, i.e. code that runs outside of service context, and thus has no decrypted credentials * yet. * * Note that read_credential_harder_and_warn() logs on its own, while read_credential() does not! * (It's a lot more complex and error prone given its TPM2 connectivity, and is generally called from * generators only where logging is OK). * * Error handling is also a bit different: if we can't find a credential we'll return 0 and NULL * pointers/zero size, rather than -ENXIO/-ENOENT. */ if (!credential_name_valid(name)) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Invalid credential name: %s", name); r = read_credential(name, ret, ret_size); if (r >= 0) return 1; /* found */ if (!IN_SET(r, -ENXIO, -ENOENT)) return log_error_errno(r, "Failed read unencrypted credential '%s': %m", name); r = get_encrypted_credentials_dir(&d); if (r == -ENXIO) goto not_found; if (r < 0) return log_error_errno(r, "Failed to determine encrypted credentials directory: %m"); fn = path_join(d, name); if (!fn) return log_oom(); r = read_full_file_full( AT_FDCWD, fn, UINT64_MAX, SIZE_MAX, READ_FULL_FILE_SECURE, NULL, (char**) &data, &sz); if (r == -ENOENT) goto not_found; if (r < 0) return log_error_errno(r, "Failed to read encrypted credential data: %m"); r = decrypt_credential_and_warn( name, now(CLOCK_REALTIME), /* tpm2_device = */ NULL, /* tpm2_signature_path = */ NULL, data, sz, ret, ret_size); if (r < 0) return r; return 1; /* found */ not_found: *ret = NULL; if (ret_size) *ret_size = 0; return 0; /* not found */ } int read_credential_strings_many_internal( const char *first_name, char **first_value, ...) { _cleanup_free_ void *b = NULL; int r, ret = 0; /* Reads a bunch of credentials into the specified buffers. If the specified buffers are already * non-NULL frees them if a credential is found. Only supports string-based credentials * (i.e. refuses embedded NUL bytes). * * 0 is returned when some or all credentials are missing. */ if (!first_name) return 0; r = read_credential(first_name, &b, NULL); if (r == -ENXIO) /* No creds passed at all? Bail immediately. */ return 0; if (r < 0) { if (r != -ENOENT) ret = r; } else free_and_replace(*first_value, b); va_list ap; va_start(ap, first_value); for (;;) { _cleanup_free_ void *bb = NULL; const char *name; char **value; name = va_arg(ap, const char *); if (!name) break; value = va_arg(ap, char **); if (*value) continue; r = read_credential(name, &bb, NULL); if (r < 0) { if (ret >= 0 && r != -ENOENT) ret = r; } else free_and_replace(*value, bb); } va_end(ap); return ret; } int read_credential_bool(const char *name) { _cleanup_free_ void *data = NULL; int r; r = read_credential(name, &data, NULL); if (r < 0) return IN_SET(r, -ENXIO, -ENOENT) ? 0 : r; return parse_boolean(data); } int get_credential_user_password(const char *username, char **ret_password, bool *ret_is_hashed) { _cleanup_(erase_and_freep) char *creds_password = NULL; _cleanup_free_ char *cn = NULL; int r; /* Try to pick up the password for this account via the credentials logic */ cn = strjoin("passwd.hashed-password.", username); if (!cn) return -ENOMEM; r = read_credential(cn, (void**) &creds_password, NULL); if (r == -ENOENT) { free(cn); cn = strjoin("passwd.plaintext-password.", username); if (!cn) return -ENOMEM; r = read_credential(cn, (void**) &creds_password, NULL); if (r < 0) log_debug_errno(r, "Couldn't read credential '%s', ignoring: %m", cn); else *ret_is_hashed = false; } else if (r < 0) log_debug_errno(r, "Couldn't read credential '%s', ignoring: %m", cn); else *ret_is_hashed = true; *ret_password = TAKE_PTR(creds_password); return r; } #if HAVE_OPENSSL #define CREDENTIAL_HOST_SECRET_SIZE 4096 static const sd_id128_t credential_app_id = SD_ID128_MAKE(d3,ac,ec,ba,0d,ad,4c,df,b8,c9,38,15,28,93,6c,58); struct credential_host_secret_format { /* The hashed machine ID of the machine this belongs to. Why? We want to ensure that each machine * gets its own secret, even if people forget to flush out this secret file. Hence we bind it to the * machine ID, for which there's hopefully a better chance it will be flushed out. We use a hashed * machine ID instead of the literal one, because it's trivial to, and it might be a good idea not * being able to directly associate a secret key file with a host. */ sd_id128_t machine_id; /* The actual secret key */ uint8_t data[CREDENTIAL_HOST_SECRET_SIZE]; } _packed_; static void warn_not_encrypted(int fd, CredentialSecretFlags flags, const char *dirname, const char *filename) { int r; assert(fd >= 0); assert(dirname); assert(filename); if (!FLAGS_SET(flags, CREDENTIAL_SECRET_WARN_NOT_ENCRYPTED)) return; r = fd_is_encrypted(fd); if (r < 0) log_debug_errno(r, "Failed to determine if credential secret file '%s/%s' is encrypted.", dirname, filename); else if (r == 0) log_warning("Credential secret file '%s/%s' is not located on encrypted media, using anyway.", dirname, filename); } static int make_credential_host_secret( int dfd, const sd_id128_t machine_id, CredentialSecretFlags flags, const char *dirname, const char *fn, void **ret_data, size_t *ret_size) { _cleanup_free_ char *t = NULL; _cleanup_close_ int fd = -EBADF; int r; assert(dfd >= 0); assert(fn); /* For non-root users creating a temporary file using the openat(2) over "." will fail later, in the * linkat(2) step at the end. The reason is that linkat(2) requires the CAP_DAC_READ_SEARCH * capability when it uses the AT_EMPTY_PATH flag. */ if (have_effective_cap(CAP_DAC_READ_SEARCH) > 0) { fd = openat(dfd, ".", O_CLOEXEC|O_WRONLY|O_TMPFILE, 0400); if (fd < 0) log_debug_errno(errno, "Failed to create temporary credential file with O_TMPFILE, proceeding without: %m"); } if (fd < 0) { if (asprintf(&t, "credential.secret.%016" PRIx64, random_u64()) < 0) return -ENOMEM; fd = openat(dfd, t, O_CLOEXEC|O_WRONLY|O_CREAT|O_EXCL|O_NOFOLLOW, 0400); if (fd < 0) return -errno; } r = chattr_secret(fd, 0); if (r < 0) log_debug_errno(r, "Failed to set file attributes for secrets file, ignoring: %m"); struct credential_host_secret_format buf = { .machine_id = machine_id, }; CLEANUP_ERASE(buf); r = crypto_random_bytes(buf.data, sizeof(buf.data)); if (r < 0) goto fail; r = loop_write(fd, &buf, sizeof(buf)); if (r < 0) goto fail; if (fsync(fd) < 0) { r = -errno; goto fail; } warn_not_encrypted(fd, flags, dirname, fn); if (t) { r = rename_noreplace(dfd, t, dfd, fn); if (r < 0) goto fail; t = mfree(t); } else if (linkat(fd, "", dfd, fn, AT_EMPTY_PATH) < 0) { r = -errno; goto fail; } if (fsync(dfd) < 0) { r = -errno; goto fail; } if (ret_data) { void *copy; copy = memdup(buf.data, sizeof(buf.data)); if (!copy) { r = -ENOMEM; goto fail; } *ret_data = copy; } if (ret_size) *ret_size = sizeof(buf.data); return 0; fail: if (t && unlinkat(dfd, t, 0) < 0) log_debug_errno(errno, "Failed to remove temporary credential key: %m"); return r; } int get_credential_host_secret(CredentialSecretFlags flags, void **ret, size_t *ret_size) { _cleanup_free_ char *_dirname = NULL, *_filename = NULL; _cleanup_close_ int dfd = -EBADF; sd_id128_t machine_id; const char *dirname, *filename; int r; r = sd_id128_get_machine_app_specific(credential_app_id, &machine_id); if (r < 0) return r; const char *e = secure_getenv("SYSTEMD_CREDENTIAL_SECRET"); if (e) { if (!path_is_normalized(e)) return -EINVAL; if (!path_is_absolute(e)) return -EINVAL; r = path_extract_directory(e, &_dirname); if (r < 0) return r; r = path_extract_filename(e, &_filename); if (r < 0) return r; dirname = _dirname; filename = _filename; } else { dirname = "/var/lib/systemd"; filename = "credential.secret"; } assert(dirname); assert(filename); mkdir_parents(dirname, 0755); dfd = open_mkdir_at(AT_FDCWD, dirname, O_CLOEXEC, 0755); if (dfd < 0) return log_debug_errno(dfd, "Failed to create or open directory '%s': %m", dirname); if (FLAGS_SET(flags, CREDENTIAL_SECRET_FAIL_ON_TEMPORARY_FS)) { r = fd_is_temporary_fs(dfd); if (r < 0) return log_debug_errno(r, "Failed to check directory '%s': %m", dirname); if (r > 0) return log_debug_errno(SYNTHETIC_ERRNO(ENOMEDIUM), "Directory '%s' is on a temporary file system, refusing.", dirname); } for (unsigned attempt = 0;; attempt++) { _cleanup_(erase_and_freep) struct credential_host_secret_format *f = NULL; _cleanup_close_ int fd = -EBADF; size_t l = 0; ssize_t n = 0; struct stat st; if (attempt >= 3) /* Somebody is playing games with us */ return log_debug_errno(SYNTHETIC_ERRNO(EIO), "All attempts to create secret store in %s failed.", dirname); fd = openat(dfd, filename, O_CLOEXEC|O_RDONLY|O_NOCTTY|O_NOFOLLOW); if (fd < 0) { if (errno != ENOENT || !FLAGS_SET(flags, CREDENTIAL_SECRET_GENERATE)) return log_debug_errno(errno, "Failed to open %s/%s: %m", dirname, filename); r = make_credential_host_secret(dfd, machine_id, flags, dirname, filename, ret, ret_size); if (r == -EEXIST) { log_debug_errno(r, "Credential secret %s/%s appeared while we were creating it, rereading.", dirname, filename); continue; } if (r < 0) return log_debug_errno(r, "Failed to create credential secret %s/%s: %m", dirname, filename); return 0; } if (fstat(fd, &st) < 0) return log_debug_errno(errno, "Failed to stat %s/%s: %m", dirname, filename); r = stat_verify_regular(&st); if (r < 0) return log_debug_errno(r, "%s/%s is not a regular file: %m", dirname, filename); if (st.st_nlink == 0) /* Deleted by now, try again */ continue; if (st.st_nlink > 1) /* Our deletion check won't work if hardlinked somewhere else */ return log_debug_errno(SYNTHETIC_ERRNO(EPERM), "%s/%s has too many links, refusing.", dirname, filename); if ((st.st_mode & 07777) != 0400) /* Don't use file if not 0400 access mode */ return log_debug_errno(SYNTHETIC_ERRNO(EPERM), "%s/%s has permissive access mode, refusing.", dirname, filename); l = st.st_size; if (l < offsetof(struct credential_host_secret_format, data) + 1) return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "%s/%s is too small, refusing.", dirname, filename); if (l > 16*1024*1024) return log_debug_errno(SYNTHETIC_ERRNO(E2BIG), "%s/%s is too big, refusing.", dirname, filename); f = malloc(l+1); if (!f) return log_oom_debug(); n = read(fd, f, l+1); if (n < 0) return log_debug_errno(errno, "Failed to read %s/%s: %m", dirname, filename); if ((size_t) n != l) /* What? The size changed? */ return log_debug_errno(SYNTHETIC_ERRNO(EIO), "Failed to read %s/%s: %m", dirname, filename); if (sd_id128_equal(machine_id, f->machine_id)) { size_t sz; warn_not_encrypted(fd, flags, dirname, filename); sz = l - offsetof(struct credential_host_secret_format, data); assert(sz > 0); if (ret) { void *copy; assert(sz <= sizeof(f->data)); /* Ensure we don't read past f->data bounds */ copy = memdup(f->data, sz); if (!copy) return log_oom_debug(); *ret = copy; } if (ret_size) *ret_size = sz; return 0; } /* Hmm, this secret is from somewhere else. Let's delete the file. Let's first acquire a lock * to ensure we are the only ones accessing the file while we delete it. */ if (flock(fd, LOCK_EX) < 0) return log_debug_errno(errno, "Failed to flock %s/%s: %m", dirname, filename); /* Before we delete it check that the file is still linked into the file system */ if (fstat(fd, &st) < 0) return log_debug_errno(errno, "Failed to stat %s/%s: %m", dirname, filename); if (st.st_nlink == 0) /* Already deleted by now? */ continue; if (st.st_nlink != 1) /* Safety check, someone is playing games with us */ return log_debug_errno(SYNTHETIC_ERRNO(EPERM), "%s/%s unexpectedly has too many links.", dirname, filename); if (unlinkat(dfd, filename, 0) < 0) return log_debug_errno(errno, "Failed to unlink %s/%s: %m", dirname, filename); /* And now try again */ } } /* Construction is like this: * * A symmetric encryption key is derived from: * * 1. Either the "host" key (a key stored in /var/lib/credential.secret) * * 2. A key generated by letting the TPM2 calculate an HMAC hash of some nonce we pass to it, keyed * by a key derived from its internal seed key. * * 3. The concatenation of the above. * * 4. Or a fixed "empty" key. This will not provide confidentiality or authenticity, of course, but is * useful to encode credentials for the initrd on TPM-less systems, where we simply have no better * concept to bind things to. Note that decryption of a key set up like this will be refused on * systems that have a TPM and have SecureBoot enabled. * * The above is hashed with SHA256 which is then used as encryption key for AES256-GCM. The encrypted * credential is a short (unencrypted) header describing which of the three keys to use, the IV to use for * AES256-GCM and some more meta information (sizes of certain objects) that is strictly speaking redundant, * but kinda nice to have since we can have a more generic parser. If the TPM2 key is used this is followed * by another (unencrypted) header, with information about the TPM2 policy used (specifically: the PCR mask * to bind against, and a hash of the resulting policy — the latter being redundant, but speeding up things a * bit, since we can more quickly refuse PCR state), followed by a sealed/exported TPM2 HMAC key. This is * then followed by the encrypted data, which begins with a metadata header (which contains validity * timestamps as well as the credential name), followed by the actual credential payload. The file ends in * the AES256-GCM tag. To make things simple, the AES256-GCM AAD covers the main and the TPM2 header in * full. This means the whole file is either protected by AAD, or is ciphertext, or is the tag. No * unprotected data is included. */ struct _packed_ encrypted_credential_header { sd_id128_t id; le32_t key_size; le32_t block_size; le32_t iv_size; le32_t tag_size; uint8_t iv[]; /* Followed by NUL bytes until next 8 byte boundary */ }; struct _packed_ tpm2_credential_header { le64_t pcr_mask; /* Note that the spec for PC Clients only mandates 24 PCRs, and that's what systems * generally have. But keep the door open for more. */ le16_t pcr_bank; /* For now, either TPM2_ALG_SHA256 or TPM2_ALG_SHA1 */ le16_t primary_alg; /* Primary key algorithm (either TPM2_ALG_RSA or TPM2_ALG_ECC for now) */ le32_t blob_size; le32_t policy_hash_size; uint8_t policy_hash_and_blob[]; /* Followed by NUL bytes until next 8 byte boundary */ }; struct _packed_ tpm2_public_key_credential_header { le64_t pcr_mask; /* PCRs used for the public key PCR policy (usually just PCR 11, i.e. the unified kernel) */ le32_t size; /* Size of DER public key */ uint8_t data[]; /* DER public key */ /* Followed by NUL bytes until next 8 byte boundary */ }; struct _packed_ metadata_credential_header { le64_t timestamp; le64_t not_after; le32_t name_size; char name[]; /* Followed by NUL bytes until next 8 byte boundary */ }; /* Some generic limit for parts of the encrypted credential for which we don't know the right size ahead of * time, but where we are really sure it won't be larger than this. Should be larger than any possible IV, * padding, tag size and so on. This is purely used for early filtering out of invalid sizes. */ #define CREDENTIAL_FIELD_SIZE_MAX (16U*1024U) static int sha256_hash_host_and_tpm2_key( const void *host_key, size_t host_key_size, const void *tpm2_key, size_t tpm2_key_size, uint8_t ret[static SHA256_DIGEST_LENGTH]) { _cleanup_(EVP_MD_CTX_freep) EVP_MD_CTX *md = NULL; unsigned l; assert(host_key_size == 0 || host_key); assert(tpm2_key_size == 0 || tpm2_key); assert(ret); /* Combines the host key and the TPM2 HMAC hash into a SHA256 hash value we'll use as symmetric encryption key. */ md = EVP_MD_CTX_new(); if (!md) return log_oom(); if (EVP_DigestInit_ex(md, EVP_sha256(), NULL) != 1) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to initial SHA256 context."); if (host_key && EVP_DigestUpdate(md, host_key, host_key_size) != 1) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to hash host key."); if (tpm2_key && EVP_DigestUpdate(md, tpm2_key, tpm2_key_size) != 1) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to hash TPM2 key."); assert(EVP_MD_CTX_size(md) == SHA256_DIGEST_LENGTH); if (EVP_DigestFinal_ex(md, ret, &l) != 1) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to finalize SHA256 hash."); assert(l == SHA256_DIGEST_LENGTH); return 0; } 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_hash_pcr_mask, const char *tpm2_pubkey_path, uint32_t tpm2_pubkey_pcr_mask, const void *input, size_t input_size, void **ret, size_t *ret_size) { _cleanup_(EVP_CIPHER_CTX_freep) EVP_CIPHER_CTX *context = NULL; _cleanup_(erase_and_freep) void *host_key = NULL, *tpm2_key = NULL; size_t host_key_size = 0, tpm2_key_size = 0, tpm2_blob_size = 0, tpm2_policy_hash_size = 0, output_size, p, ml; _cleanup_free_ void *tpm2_blob = NULL, *tpm2_policy_hash = NULL, *iv = NULL, *output = NULL; _cleanup_free_ struct metadata_credential_header *m = NULL; uint16_t tpm2_pcr_bank = 0, tpm2_primary_alg = 0; struct encrypted_credential_header *h; int ksz, bsz, ivsz, tsz, added, r; _cleanup_free_ void *pubkey = NULL; size_t pubkey_size = 0; uint8_t md[SHA256_DIGEST_LENGTH]; const EVP_CIPHER *cc; sd_id128_t id; assert(input || input_size == 0); assert(ret); assert(ret_size); if (!sd_id128_in_set(with_key, _CRED_AUTO, _CRED_AUTO_INITRD, CRED_AES256_GCM_BY_HOST, CRED_AES256_GCM_BY_TPM2_HMAC, 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)) 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)) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Invalid credential name: %s", name); if (not_after != USEC_INFINITY && timestamp != USEC_INFINITY && not_after < timestamp) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Credential is invalidated before it is valid (" USEC_FMT " < " USEC_FMT ").", not_after, timestamp); if (DEBUG_LOGGING) { char buf[FORMAT_TIMESTAMP_MAX]; if (name) log_debug("Including credential name '%s' in encrypted credential.", name); if (timestamp != USEC_INFINITY) log_debug("Including timestamp '%s' in encrypted credential.", format_timestamp(buf, sizeof(buf), timestamp)); if (not_after != USEC_INFINITY) log_debug("Including not-after timestamp '%s' in encrypted credential.", format_timestamp(buf, sizeof(buf), not_after)); } if (sd_id128_in_set(with_key, _CRED_AUTO, CRED_AES256_GCM_BY_HOST, CRED_AES256_GCM_BY_HOST_AND_TPM2_HMAC, CRED_AES256_GCM_BY_HOST_AND_TPM2_HMAC_WITH_PK)) { r = get_credential_host_secret( CREDENTIAL_SECRET_GENERATE| CREDENTIAL_SECRET_WARN_NOT_ENCRYPTED| (sd_id128_equal(with_key, _CRED_AUTO) ? CREDENTIAL_SECRET_FAIL_ON_TEMPORARY_FS : 0), &host_key, &host_key_size); if (r == -ENOMEDIUM && sd_id128_equal(with_key, _CRED_AUTO)) log_debug_errno(r, "Credential host secret location on temporary file system, not using."); else if (r < 0) return log_error_errno(r, "Failed to determine local credential host secret: %m"); } #if HAVE_TPM2 bool try_tpm2; if (sd_id128_in_set(with_key, _CRED_AUTO, _CRED_AUTO_INITRD)) { /* If automatic mode is selected lets see if a TPM2 it is present. If we are running in a * container tpm2_support will detect this, and will return a different flag combination of * TPM2_SUPPORT_FULL, effectively skipping the use of TPM2 when inside one. */ try_tpm2 = tpm2_support() == TPM2_SUPPORT_FULL; if (!try_tpm2) log_debug("System lacks TPM2 support or running in a container, not attempting to use TPM2."); } else try_tpm2 = sd_id128_in_set(with_key, CRED_AES256_GCM_BY_TPM2_HMAC, 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); if (try_tpm2) { if (sd_id128_in_set(with_key, _CRED_AUTO, _CRED_AUTO_INITRD, CRED_AES256_GCM_BY_TPM2_HMAC_WITH_PK, CRED_AES256_GCM_BY_HOST_AND_TPM2_HMAC_WITH_PK)) { /* Load public key for PCR policies, if one is specified, or explicitly requested */ r = tpm2_load_pcr_public_key(tpm2_pubkey_path, &pubkey, &pubkey_size); if (r < 0) { if (tpm2_pubkey_path || r != -ENOENT || !sd_id128_in_set(with_key, _CRED_AUTO, _CRED_AUTO_INITRD)) return log_error_errno(r, "Failed read TPM PCR public key: %m"); log_debug_errno(r, "Failed to read TPM2 PCR public key, proceeding without: %m"); } } if (!pubkey) tpm2_pubkey_pcr_mask = 0; _cleanup_(tpm2_context_unrefp) Tpm2Context *tpm2_context = NULL; r = tpm2_context_new_or_warn(tpm2_device, &tpm2_context); if (r < 0) return r; r = tpm2_get_best_pcr_bank(tpm2_context, tpm2_hash_pcr_mask | tpm2_pubkey_pcr_mask, &tpm2_pcr_bank); if (r < 0) return log_error_errno(r, "Could not find best pcr bank: %m"); TPML_PCR_SELECTION tpm2_hash_pcr_selection; tpm2_tpml_pcr_selection_from_mask(tpm2_hash_pcr_mask, tpm2_pcr_bank, &tpm2_hash_pcr_selection); _cleanup_free_ Tpm2PCRValue *tpm2_hash_pcr_values = NULL; size_t tpm2_n_hash_pcr_values; r = tpm2_pcr_read(tpm2_context, &tpm2_hash_pcr_selection, &tpm2_hash_pcr_values, &tpm2_n_hash_pcr_values); if (r < 0) return log_error_errno(r, "Could not read PCR values: %m"); TPM2B_PUBLIC public; if (pubkey) { r = tpm2_tpm2b_public_from_pem(pubkey, pubkey_size, &public); if (r < 0) return log_error_errno(r, "Could not convert public key to TPM2B_PUBLIC: %m"); } TPM2B_DIGEST tpm2_policy = TPM2B_DIGEST_MAKE(NULL, TPM2_SHA256_DIGEST_SIZE); r = tpm2_calculate_sealing_policy( tpm2_hash_pcr_values, tpm2_n_hash_pcr_values, pubkey ? &public : NULL, /* use_pin= */ false, /* pcrlock_policy= */ NULL, &tpm2_policy); if (r < 0) return log_error_errno(r, "Could not calculate sealing policy digest: %m"); r = tpm2_seal(tpm2_context, /* seal_key_handle= */ 0, &tpm2_policy, /* pin= */ NULL, &tpm2_key, &tpm2_key_size, &tpm2_blob, &tpm2_blob_size, &tpm2_primary_alg, /* ret_srk_buf= */ NULL, /* ret_srk_buf_size= */ NULL); if (r < 0) { if (sd_id128_equal(with_key, _CRED_AUTO_INITRD)) log_warning("TPM2 present and used, but we didn't manage to talk to it. Credential will be refused if SecureBoot is enabled."); else if (!sd_id128_equal(with_key, _CRED_AUTO)) return log_error_errno(r, "Failed to seal to TPM2: %m"); log_notice_errno(r, "TPM2 sealing didn't work, continuing without TPM2: %m"); } tpm2_policy_hash_size = tpm2_policy.size; tpm2_policy_hash = malloc(tpm2_policy_hash_size); if (!tpm2_policy_hash) return log_oom(); memcpy(tpm2_policy_hash, tpm2_policy.buffer, tpm2_policy_hash_size); assert(tpm2_blob_size <= CREDENTIAL_FIELD_SIZE_MAX); assert(tpm2_policy_hash_size <= CREDENTIAL_FIELD_SIZE_MAX); } #endif if (sd_id128_in_set(with_key, _CRED_AUTO, _CRED_AUTO_INITRD)) { /* Let's settle the key type in auto mode now. */ if (host_key && tpm2_key) id = pubkey ? CRED_AES256_GCM_BY_HOST_AND_TPM2_HMAC_WITH_PK : CRED_AES256_GCM_BY_HOST_AND_TPM2_HMAC; else if (tpm2_key) id = pubkey ? CRED_AES256_GCM_BY_TPM2_HMAC_WITH_PK : CRED_AES256_GCM_BY_TPM2_HMAC; 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; 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)) 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 */ r = sha256_hash_host_and_tpm2_key(host_key, host_key_size, tpm2_key, tpm2_key_size, md); if (r < 0) return r; assert_se(cc = EVP_aes_256_gcm()); ksz = EVP_CIPHER_key_length(cc); assert(ksz == sizeof(md)); bsz = EVP_CIPHER_block_size(cc); assert(bsz > 0); assert((size_t) bsz <= CREDENTIAL_FIELD_SIZE_MAX); ivsz = EVP_CIPHER_iv_length(cc); if (ivsz > 0) { assert((size_t) ivsz <= CREDENTIAL_FIELD_SIZE_MAX); iv = malloc(ivsz); if (!iv) return log_oom(); r = crypto_random_bytes(iv, ivsz); if (r < 0) return log_error_errno(r, "Failed to acquired randomized IV: %m"); } tsz = 16; /* FIXME: On OpenSSL 3 there is EVP_CIPHER_CTX_get_tag_length(), until then let's hardcode this */ context = EVP_CIPHER_CTX_new(); if (!context) return log_error_errno(SYNTHETIC_ERRNO(ENOMEM), "Failed to allocate encryption object: %s", ERR_error_string(ERR_get_error(), NULL)); if (EVP_EncryptInit_ex(context, cc, NULL, md, iv) != 1) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to initialize encryption context: %s", ERR_error_string(ERR_get_error(), NULL)); /* Just an upper estimate */ output_size = ALIGN8(offsetof(struct encrypted_credential_header, iv) + ivsz) + ALIGN8(tpm2_key ? offsetof(struct tpm2_credential_header, policy_hash_and_blob) + tpm2_blob_size + tpm2_policy_hash_size : 0) + ALIGN8(pubkey ? offsetof(struct tpm2_public_key_credential_header, data) + pubkey_size : 0) + ALIGN8(offsetof(struct metadata_credential_header, name) + strlen_ptr(name)) + input_size + 2U * (size_t) bsz + tsz; output = malloc0(output_size); if (!output) return log_oom(); h = (struct encrypted_credential_header*) output; h->id = id; h->block_size = htole32(bsz); h->key_size = htole32(ksz); h->tag_size = htole32(tsz); h->iv_size = htole32(ivsz); memcpy(h->iv, iv, ivsz); p = ALIGN8(offsetof(struct encrypted_credential_header, iv) + ivsz); if (tpm2_key) { struct tpm2_credential_header *t; t = (struct tpm2_credential_header*) ((uint8_t*) output + p); t->pcr_mask = htole64(tpm2_hash_pcr_mask); t->pcr_bank = htole16(tpm2_pcr_bank); t->primary_alg = htole16(tpm2_primary_alg); t->blob_size = htole32(tpm2_blob_size); t->policy_hash_size = htole32(tpm2_policy_hash_size); memcpy(t->policy_hash_and_blob, tpm2_blob, tpm2_blob_size); memcpy(t->policy_hash_and_blob + tpm2_blob_size, tpm2_policy_hash, tpm2_policy_hash_size); p += ALIGN8(offsetof(struct tpm2_credential_header, policy_hash_and_blob) + tpm2_blob_size + tpm2_policy_hash_size); } if (pubkey) { struct tpm2_public_key_credential_header *z; z = (struct tpm2_public_key_credential_header*) ((uint8_t*) output + p); z->pcr_mask = htole64(tpm2_pubkey_pcr_mask); z->size = htole32(pubkey_size); memcpy(z->data, pubkey, pubkey_size); p += ALIGN8(offsetof(struct tpm2_public_key_credential_header, data) + pubkey_size); } /* Pass the encrypted + TPM2 header as AAD */ if (EVP_EncryptUpdate(context, NULL, &added, output, p) != 1) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to write AAD data: %s", ERR_error_string(ERR_get_error(), NULL)); /* Now construct the metadata header */ ml = strlen_ptr(name); m = malloc0(ALIGN8(offsetof(struct metadata_credential_header, name) + ml)); if (!m) return log_oom(); m->timestamp = htole64(timestamp); m->not_after = htole64(not_after); m->name_size = htole32(ml); memcpy_safe(m->name, name, ml); /* And encrypt the metadata header */ if (EVP_EncryptUpdate(context, (uint8_t*) output + p, &added, (const unsigned char*) m, ALIGN8(offsetof(struct metadata_credential_header, name) + ml)) != 1) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to encrypt metadata header: %s", ERR_error_string(ERR_get_error(), NULL)); assert(added >= 0); assert((size_t) added <= output_size - p); p += added; /* Then encrypt the plaintext */ if (EVP_EncryptUpdate(context, (uint8_t*) output + p, &added, input, input_size) != 1) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to encrypt data: %s", ERR_error_string(ERR_get_error(), NULL)); assert(added >= 0); assert((size_t) added <= output_size - p); p += added; /* Finalize */ if (EVP_EncryptFinal_ex(context, (uint8_t*) output + p, &added) != 1) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to finalize data encryption: %s", ERR_error_string(ERR_get_error(), NULL)); assert(added >= 0); assert((size_t) added <= output_size - p); p += added; assert(p <= output_size - tsz); /* Append tag */ if (EVP_CIPHER_CTX_ctrl(context, EVP_CTRL_GCM_GET_TAG, tsz, (uint8_t*) output + p) != 1) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to get tag: %s", ERR_error_string(ERR_get_error(), NULL)); p += tsz; assert(p <= output_size); if (DEBUG_LOGGING && input_size > 0) { size_t base64_size; base64_size = DIV_ROUND_UP(p * 4, 3); /* Include base64 size increase in debug output */ assert(base64_size >= input_size); log_debug("Input of %zu bytes grew to output of %zu bytes (+%2zu%%).", input_size, base64_size, base64_size * 100 / input_size - 100); } *ret = TAKE_PTR(output); *ret_size = p; return 0; } int decrypt_credential_and_warn( const char *validate_name, usec_t validate_timestamp, const char *tpm2_device, const char *tpm2_signature_path, const void *input, size_t input_size, void **ret, size_t *ret_size) { _cleanup_(erase_and_freep) void *host_key = NULL, *tpm2_key = NULL, *plaintext = NULL; _cleanup_(json_variant_unrefp) JsonVariant *signature_json = NULL; _cleanup_(EVP_CIPHER_CTX_freep) EVP_CIPHER_CTX *context = NULL; size_t host_key_size = 0, tpm2_key_size = 0, plaintext_size, p, hs; 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; const EVP_CIPHER *cc; int r, added; assert(input || input_size == 0); assert(ret); assert(ret_size); h = (struct encrypted_credential_header*) input; /* The ID must fit in, for the current and all future formats */ if (input_size < sizeof(h->id)) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Encrypted file too short."); 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); if (!with_host_key && !with_tpm2 && !is_tpm2_absent) return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "Unknown encryption format, or corrupted data: %m"); if (with_tpm2_pk) { r = tpm2_load_pcr_signature(tpm2_signature_path, &signature_json); if (r < 0) return log_error_errno(r, "Failed to load pcr signature: %m"); } if (is_tpm2_absent) { /* 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 * different codeflow for TPM2 and non-TPM2 codepaths. Of course, credentials encoded this * way offer no confidentiality nor authenticity. Because of that it's important we refuse to * use them on systems that actually *do* have a TPM2 chip – if we are in SecureBoot * mode. Otherwise an attacker could hand us credentials like this and we'd use them thinking * they are trusted, even though they are not. */ if (efi_has_tpm2()) { if (is_efi_secure_boot()) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Credential uses fixed key for fallback use when TPM2 is absent — but TPM2 is present, and SecureBoot is enabled, refusing."); log_warning("Credential uses fixed key for use when TPM2 is absent, but TPM2 is present! Accepting anyway, since SecureBoot is disabled."); } else log_debug("Credential uses fixed key for use when TPM2 is absent, and TPM2 indeed is absent. Accepting."); } /* Now we know the minimum header size */ if (input_size < offsetof(struct encrypted_credential_header, iv)) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Encrypted file too short."); /* Verify some basic header values */ if (le32toh(h->key_size) != sizeof(md)) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Unexpected key size in header."); if (le32toh(h->block_size) <= 0 || le32toh(h->block_size) > CREDENTIAL_FIELD_SIZE_MAX) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Unexpected block size in header."); if (le32toh(h->iv_size) > CREDENTIAL_FIELD_SIZE_MAX) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "IV size too large."); if (le32toh(h->tag_size) != 16) /* FIXME: On OpenSSL 3, let's verify via EVP_CIPHER_CTX_get_tag_length() */ return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Unexpected tag size in header."); /* Ensure we have space for the full header now (we don't know the size of the name hence this is a * lower limit only) */ if (input_size < ALIGN8(offsetof(struct encrypted_credential_header, iv) + le32toh(h->iv_size)) + ALIGN8(with_tpm2 ? offsetof(struct tpm2_credential_header, policy_hash_and_blob) : 0) + ALIGN8(with_tpm2_pk ? offsetof(struct tpm2_public_key_credential_header, data) : 0) + ALIGN8(offsetof(struct metadata_credential_header, name)) + le32toh(h->tag_size)) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Encrypted file too short."); p = ALIGN8(offsetof(struct encrypted_credential_header, iv) + le32toh(h->iv_size)); if (with_tpm2) { #if HAVE_TPM2 struct tpm2_credential_header* t = (struct tpm2_credential_header*) ((uint8_t*) input + p); struct tpm2_public_key_credential_header *z = NULL; if (!TPM2_PCR_MASK_VALID(t->pcr_mask)) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "TPM2 PCR mask out of range."); if (!tpm2_hash_alg_to_string(le16toh(t->pcr_bank))) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "TPM2 PCR bank invalid or not supported"); if (!tpm2_asym_alg_to_string(le16toh(t->primary_alg))) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "TPM2 primary key algorithm invalid or not supported."); if (le32toh(t->blob_size) > CREDENTIAL_FIELD_SIZE_MAX) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Unexpected TPM2 blob size."); if (le32toh(t->policy_hash_size) > CREDENTIAL_FIELD_SIZE_MAX) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Unexpected TPM2 policy hash size."); /* Ensure we have space for the full TPM2 header now (still don't know the name, and its size * though, hence still just a lower limit test only) */ if (input_size < ALIGN8(offsetof(struct encrypted_credential_header, iv) + le32toh(h->iv_size)) + ALIGN8(offsetof(struct tpm2_credential_header, policy_hash_and_blob) + le32toh(t->blob_size) + le32toh(t->policy_hash_size)) + ALIGN8(with_tpm2_pk ? offsetof(struct tpm2_public_key_credential_header, data) : 0) + ALIGN8(offsetof(struct metadata_credential_header, name)) + le32toh(h->tag_size)) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Encrypted file too short."); p += ALIGN8(offsetof(struct tpm2_credential_header, policy_hash_and_blob) + le32toh(t->blob_size) + le32toh(t->policy_hash_size)); if (with_tpm2_pk) { z = (struct tpm2_public_key_credential_header*) ((uint8_t*) input + p); if (!TPM2_PCR_MASK_VALID(le64toh(z->pcr_mask)) || le64toh(z->pcr_mask) == 0) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "TPM2 PCR mask out of range."); if (le32toh(z->size) > PUBLIC_KEY_MAX) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Unexpected public key size."); if (input_size < ALIGN8(offsetof(struct encrypted_credential_header, iv) + le32toh(h->iv_size)) + ALIGN8(offsetof(struct tpm2_credential_header, policy_hash_and_blob) + le32toh(t->blob_size) + le32toh(t->policy_hash_size)) + ALIGN8(offsetof(struct tpm2_public_key_credential_header, data) + le32toh(z->size)) + ALIGN8(offsetof(struct metadata_credential_header, name)) + le32toh(h->tag_size)) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Encrypted file too short."); p += ALIGN8(offsetof(struct tpm2_public_key_credential_header, data) + le32toh(z->size)); } _cleanup_(tpm2_context_unrefp) Tpm2Context *tpm2_context = NULL; r = tpm2_context_new(tpm2_device, &tpm2_context); if (r < 0) return r; // TODO: Add the SRK data to the credential structure so it can be plumbed // through and used to verify the TPM session. r = tpm2_unseal(tpm2_context, le64toh(t->pcr_mask), le16toh(t->pcr_bank), z ? z->data : NULL, z ? le32toh(z->size) : 0, z ? le64toh(z->pcr_mask) : 0, signature_json, /* pin= */ NULL, /* pcrlock_policy= */ NULL, le16toh(t->primary_alg), t->policy_hash_and_blob, le32toh(t->blob_size), t->policy_hash_and_blob + le32toh(t->blob_size), le32toh(t->policy_hash_size), /* srk_buf= */ NULL, /* srk_buf_size= */ 0, &tpm2_key, &tpm2_key_size); if (r < 0) return log_error_errno(r, "Failed to unseal secret using TPM2: %m"); #else return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "Credential requires TPM2 support, but TPM2 support not available."); #endif } if (with_host_key) { r = get_credential_host_secret( 0, &host_key, &host_key_size); if (r < 0) return log_error_errno(r, "Failed to determine local credential key: %m"); } if (is_tpm2_absent) 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); assert_se(cc = EVP_aes_256_gcm()); /* Make sure cipher expectations match the header */ if (EVP_CIPHER_key_length(cc) != (int) le32toh(h->key_size)) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Unexpected key size in header."); if (EVP_CIPHER_block_size(cc) != (int) le32toh(h->block_size)) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Unexpected block size in header."); context = EVP_CIPHER_CTX_new(); if (!context) return log_error_errno(SYNTHETIC_ERRNO(ENOMEM), "Failed to allocate decryption object: %s", ERR_error_string(ERR_get_error(), NULL)); if (EVP_DecryptInit_ex(context, cc, NULL, NULL, NULL) != 1) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to initialize decryption context: %s", ERR_error_string(ERR_get_error(), NULL)); if (EVP_CIPHER_CTX_ctrl(context, EVP_CTRL_GCM_SET_IVLEN, le32toh(h->iv_size), NULL) != 1) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to set IV size on decryption context: %s", ERR_error_string(ERR_get_error(), NULL)); if (EVP_DecryptInit_ex(context, NULL, NULL, md, h->iv) != 1) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to set IV and key: %s", ERR_error_string(ERR_get_error(), NULL)); if (EVP_DecryptUpdate(context, NULL, &added, input, p) != 1) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to write AAD data: %s", ERR_error_string(ERR_get_error(), NULL)); plaintext = malloc(input_size - p - le32toh(h->tag_size)); if (!plaintext) return -ENOMEM; if (EVP_DecryptUpdate( context, plaintext, &added, (uint8_t*) input + p, input_size - p - le32toh(h->tag_size)) != 1) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to decrypt data: %s", ERR_error_string(ERR_get_error(), NULL)); assert(added >= 0); assert((size_t) added <= input_size - p - le32toh(h->tag_size)); plaintext_size = added; if (EVP_CIPHER_CTX_ctrl(context, EVP_CTRL_GCM_SET_TAG, le32toh(h->tag_size), (uint8_t*) input + input_size - le32toh(h->tag_size)) != 1) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to set tag: %s", ERR_error_string(ERR_get_error(), NULL)); if (EVP_DecryptFinal_ex(context, (uint8_t*) plaintext + plaintext_size, &added) != 1) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Decryption failed (incorrect key?): %s", ERR_error_string(ERR_get_error(), NULL)); plaintext_size += added; if (plaintext_size < ALIGN8(offsetof(struct metadata_credential_header, name))) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Metadata header incomplete."); m = plaintext; if (le64toh(m->timestamp) != USEC_INFINITY && le64toh(m->not_after) != USEC_INFINITY && le64toh(m->timestamp) >= le64toh(m->not_after)) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Timestamps of credential are not in order, refusing."); if (le32toh(m->name_size) > CREDENTIAL_NAME_MAX) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Embedded credential name too long, refusing."); hs = ALIGN8(offsetof(struct metadata_credential_header, name) + le32toh(m->name_size)); if (plaintext_size < hs) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Metadata header incomplete."); if (le32toh(m->name_size) > 0) { _cleanup_free_ char *embedded_name = NULL; r = make_cstring(m->name, le32toh(m->name_size), MAKE_CSTRING_REFUSE_TRAILING_NUL, &embedded_name); if (r < 0) return log_error_errno(r, "Unable to convert embedded credential name to C string: %m"); if (!credential_name_valid(embedded_name)) return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "Embedded credential name is not valid, refusing."); if (validate_name && !streq(embedded_name, validate_name)) { r = getenv_bool_secure("SYSTEMD_CREDENTIAL_VALIDATE_NAME"); if (r < 0 && r != -ENXIO) log_debug_errno(r, "Failed to parse $SYSTEMD_CREDENTIAL_VALIDATE_NAME: %m"); if (r != 0) return log_error_errno(SYNTHETIC_ERRNO(EREMOTE), "Embedded credential name '%s' does not match filename '%s', refusing.", embedded_name, validate_name); log_debug("Embedded credential name '%s' does not match expected name '%s', but configured to use credential anyway.", embedded_name, validate_name); } } if (validate_timestamp != USEC_INFINITY) { if (le64toh(m->timestamp) != USEC_INFINITY && le64toh(m->timestamp) > validate_timestamp) log_debug("Credential timestamp is from the future, assuming clock skew."); if (le64toh(m->not_after) != USEC_INFINITY && le64toh(m->not_after) < validate_timestamp) { r = getenv_bool_secure("SYSTEMD_CREDENTIAL_VALIDATE_NOT_AFTER"); if (r < 0 && r != -ENXIO) log_debug_errno(r, "Failed to parse $SYSTEMD_CREDENTIAL_VALIDATE_NOT_AFTER: %m"); if (r != 0) return log_error_errno(SYNTHETIC_ERRNO(ESTALE), "Credential's time passed, refusing to use."); log_debug("Credential not-after timestamp has passed, but configured to use credential anyway."); } } if (ret) { char *without_metadata; without_metadata = memdup((uint8_t*) plaintext + hs, plaintext_size - hs); if (!without_metadata) return log_oom(); *ret = without_metadata; } if (ret_size) *ret_size = plaintext_size - hs; return 0; } #else int get_credential_host_secret(CredentialSecretFlags flags, void **ret, size_t *ret_size) { return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "Support for encrypted credentials not available."); } 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_hash_pcr_mask, const char *tpm2_pubkey_path, uint32_t tpm2_pubkey_pcr_mask, const void *input, size_t input_size, void **ret, size_t *ret_size) { return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "Support for encrypted credentials not available."); } int decrypt_credential_and_warn(const char *validate_name, usec_t validate_timestamp, const char *tpm2_device, const char *tpm2_signature_path, const void *input, size_t input_size, void **ret, size_t *ret_size) { return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "Support for encrypted credentials not available."); } #endif