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creds-util.c
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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <sys/file.h>
#if HAVE_OPENSSL
#include <openssl/err.h>
#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(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 r;
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 r;
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,
&tpm2_policy);
if (r < 0)
return r;
r = tpm2_seal(tpm2_context,
&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 r;
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",