/*
* Check for self-signedness in an X.509 cert and if found, check the signature
* immediately if we can.
*/
int x509_check_for_self_signed(struct x509_certificate *cert)
{
int ret = 0;
pr_devel("==>%s()\n", __func__);
if (cert->raw_subject_size != cert->raw_issuer_size ||
memcmp(cert->raw_subject, cert->raw_issuer,
cert->raw_issuer_size) != 0)
goto not_self_signed;
if (cert->sig->auth_ids[0] || cert->sig->auth_ids[1]) {
/* If the AKID is present it may have one or two parts. If
* both are supplied, both must match.
*/
bool a = asymmetric_key_id_same(cert->skid, cert->sig->auth_ids[1]);
bool b = asymmetric_key_id_same(cert->id, cert->sig->auth_ids[0]);
if (!a && !b)
goto not_self_signed;
ret = -EKEYREJECTED;
if (((a && !b) || (b && !a)) &&
cert->sig->auth_ids[0] && cert->sig->auth_ids[1])
goto out;
}
ret = -EKEYREJECTED;
if (strcmp(cert->pub->pkey_algo, cert->sig->pkey_algo) != 0)
goto out;
ret = public_key_verify_signature(cert->pub, cert->sig);
if (ret < 0) {
if (ret == -ENOPKG) {
cert->unsupported_sig = true;
ret = 0;
}
goto out;
}
pr_devel("Cert Self-signature verified");
cert->self_signed = true;
out:
pr_devel("<==%s() = %d\n", __func__, ret);
return ret;
not_self_signed:
pr_devel("<==%s() = 0 [not]\n", __func__);
return 0;
}
/*
* Attempt to parse a data blob for a key as an X509 certificate.
*/
static int x509_key_preparse(struct key_preparsed_payload *prep)
{
struct asymmetric_key_ids *kids;
struct x509_certificate *cert;
const char *q;
size_t srlen, sulen;
char *desc = NULL, *p;
int ret;
cert = x509_cert_parse(prep->data, prep->datalen);
if (IS_ERR(cert))
return PTR_ERR(cert);
pr_devel("Cert Issuer: %s\n", cert->issuer);
pr_devel("Cert Subject: %s\n", cert->subject);
if (cert->pub->pkey_algo >= PKEY_ALGO__LAST ||
cert->sig.pkey_algo >= PKEY_ALGO__LAST ||
cert->sig.pkey_hash_algo >= PKEY_HASH__LAST ||
!pkey_algo[cert->pub->pkey_algo] ||
!pkey_algo[cert->sig.pkey_algo] ||
!hash_algo_name[cert->sig.pkey_hash_algo]) {
ret = -ENOPKG;
goto error_free_cert;
}
pr_devel("Cert Key Algo: %s\n", pkey_algo_name[cert->pub->pkey_algo]);
pr_devel("Cert Valid From: %04ld-%02d-%02d %02d:%02d:%02d\n",
cert->valid_from.tm_year + 1900, cert->valid_from.tm_mon + 1,
cert->valid_from.tm_mday, cert->valid_from.tm_hour,
cert->valid_from.tm_min, cert->valid_from.tm_sec);
pr_devel("Cert Valid To: %04ld-%02d-%02d %02d:%02d:%02d\n",
cert->valid_to.tm_year + 1900, cert->valid_to.tm_mon + 1,
cert->valid_to.tm_mday, cert->valid_to.tm_hour,
cert->valid_to.tm_min, cert->valid_to.tm_sec);
pr_devel("Cert Signature: %s + %s\n",
pkey_algo_name[cert->sig.pkey_algo],
hash_algo_name[cert->sig.pkey_hash_algo]);
cert->pub->algo = pkey_algo[cert->pub->pkey_algo];
cert->pub->id_type = PKEY_ID_X509;
/* Check the signature on the key if it appears to be self-signed */
if (!cert->authority ||
asymmetric_key_id_same(cert->skid, cert->authority)) {
ret = x509_check_signature(cert->pub, cert); /* self-signed */
if (ret < 0)
goto error_free_cert;
} else if (!prep->trusted) {
ret = x509_validate_trust(cert, get_system_trusted_keyring());
if (!ret)
prep->trusted = 1;
}
/* Propose a description */
sulen = strlen(cert->subject);
if (cert->raw_skid) {
srlen = cert->raw_skid_size
/*
* Find the key (X.509 certificate) to use to verify a PKCS#7 message. PKCS#7
* uses the issuer's name and the issuing certificate serial number for
* matching purposes. These must match the certificate issuer's name (not
* subject's name) and the certificate serial number [RFC 2315 6.7].
*/
static int pkcs7_find_key(struct pkcs7_message *pkcs7,
struct pkcs7_signed_info *sinfo)
{
struct x509_certificate *x509;
unsigned certix = 1;
kenter("%u", sinfo->index);
for (x509 = pkcs7->certs; x509; x509 = x509->next, certix++) {
/* I'm _assuming_ that the generator of the PKCS#7 message will
* encode the fields from the X.509 cert in the same way in the
* PKCS#7 message - but I can't be 100% sure of that. It's
* possible this will need element-by-element comparison.
*/
if (!asymmetric_key_id_same(x509->id, sinfo->signing_cert_id))
continue;
pr_devel("Sig %u: Found cert serial match X.509[%u]\n",
sinfo->index, certix);
if (x509->pub->pkey_algo != sinfo->sig.pkey_algo) {
pr_warn("Sig %u: X.509 algo and PKCS#7 sig algo don't match\n",
sinfo->index);
continue;
}
sinfo->signer = x509;
return 0;
}
/* The relevant X.509 cert isn't found here, but it might be found in
* the trust keyring.
*/
pr_debug("Sig %u: Issuing X.509 cert not found (#%*phN)\n",
sinfo->index,
sinfo->signing_cert_id->len, sinfo->signing_cert_id->data);
return 0;
}
/*
* Attempt to parse a data blob for a key as an X509 certificate.
*/
static int x509_key_preparse(struct key_preparsed_payload *prep)
{
struct asymmetric_key_ids *kids;
struct x509_certificate *cert;
const char *q;
size_t srlen, sulen;
char *desc = NULL, *p;
int ret;
cert = x509_cert_parse(prep->data, prep->datalen);
if (IS_ERR(cert))
return PTR_ERR(cert);
pr_devel("Cert Issuer: %s\n", cert->issuer);
pr_devel("Cert Subject: %s\n", cert->subject);
if (cert->pub->pkey_algo >= PKEY_ALGO__LAST ||
cert->sig.pkey_algo >= PKEY_ALGO__LAST ||
cert->sig.pkey_hash_algo >= PKEY_HASH__LAST ||
!pkey_algo[cert->pub->pkey_algo] ||
!pkey_algo[cert->sig.pkey_algo] ||
!hash_algo_name[cert->sig.pkey_hash_algo]) {
ret = -ENOPKG;
goto error_free_cert;
}
pr_devel("Cert Key Algo: %s\n", pkey_algo_name[cert->pub->pkey_algo]);
pr_devel("Cert Valid period: %lld-%lld\n", cert->valid_from, cert->valid_to);
pr_devel("Cert Signature: %s + %s\n",
pkey_algo_name[cert->sig.pkey_algo],
hash_algo_name[cert->sig.pkey_hash_algo]);
cert->pub->algo = pkey_algo[cert->pub->pkey_algo];
cert->pub->id_type = PKEY_ID_X509;
/* Check the signature on the key if it appears to be self-signed */
if (!cert->akid_skid ||
asymmetric_key_id_same(cert->skid, cert->akid_skid)) {
ret = x509_check_signature(cert->pub, cert); /* self-signed */
if (ret < 0)
goto error_free_cert;
} else if (!prep->trusted) {
ret = x509_validate_trust(cert, get_system_trusted_keyring());
if (!ret)
prep->trusted = 1;
}
/* Propose a description */
sulen = strlen(cert->subject);
if (cert->raw_skid) {
srlen = cert->raw_skid_size;
q = cert->raw_skid;
} else {
srlen = cert->raw_serial_size;
q = cert->raw_serial;
}
ret = -ENOMEM;
desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL);
if (!desc)
goto error_free_cert;
p = memcpy(desc, cert->subject, sulen);
p += sulen;
*p++ = ':';
*p++ = ' ';
p = bin2hex(p, q, srlen);
*p = 0;
kids = kmalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL);
if (!kids)
goto error_free_desc;
kids->id[0] = cert->id;
kids->id[1] = cert->skid;
/* We're pinning the module by being linked against it */
__module_get(public_key_subtype.owner);
prep->type_data[0] = &public_key_subtype;
prep->type_data[1] = kids;
prep->payload[0] = cert->pub;
prep->description = desc;
prep->quotalen = 100;
/* We've finished with the certificate */
cert->pub = NULL;
cert->id = NULL;
cert->skid = NULL;
desc = NULL;
ret = 0;
error_free_desc:
kfree(desc);
error_free_cert:
x509_free_certificate(cert);
return ret;
}
/*
* Verify the internal certificate chain as best we can.
*/
static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
struct pkcs7_signed_info *sinfo)
{
struct x509_certificate *x509 = sinfo->signer, *p;
struct asymmetric_key_id *auth;
int ret;
kenter("");
for (p = pkcs7->certs; p; p = p->next)
p->seen = false;
for (;;) {
pr_debug("verify %s: %*phN\n",
x509->subject,
x509->raw_serial_size, x509->raw_serial);
x509->seen = true;
ret = x509_get_sig_params(x509);
if (ret < 0)
goto maybe_missing_crypto_in_x509;
pr_debug("- issuer %s\n", x509->issuer);
if (x509->akid_id)
pr_debug("- authkeyid.id %*phN\n",
x509->akid_id->len, x509->akid_id->data);
if (x509->akid_skid)
pr_debug("- authkeyid.skid %*phN\n",
x509->akid_skid->len, x509->akid_skid->data);
if ((!x509->akid_id && !x509->akid_skid) ||
strcmp(x509->subject, x509->issuer) == 0) {
/* If there's no authority certificate specified, then
* the certificate must be self-signed and is the root
* of the chain. Likewise if the cert is its own
* authority.
*/
pr_debug("- no auth?\n");
if (x509->raw_subject_size != x509->raw_issuer_size ||
memcmp(x509->raw_subject, x509->raw_issuer,
x509->raw_issuer_size) != 0)
return 0;
ret = x509_check_signature(x509->pub, x509);
if (ret < 0)
goto maybe_missing_crypto_in_x509;
x509->signer = x509;
pr_debug("- self-signed\n");
return 0;
}
/* Look through the X.509 certificates in the PKCS#7 message's
* list to see if the next one is there.
*/
auth = x509->akid_id;
if (auth) {
pr_debug("- want %*phN\n", auth->len, auth->data);
for (p = pkcs7->certs; p; p = p->next) {
pr_debug("- cmp [%u] %*phN\n",
p->index, p->id->len, p->id->data);
if (asymmetric_key_id_same(p->id, auth))
goto found_issuer_check_skid;
}
} else {
auth = x509->akid_skid;
pr_debug("- want %*phN\n", auth->len, auth->data);
for (p = pkcs7->certs; p; p = p->next) {
if (!p->skid)
continue;
pr_debug("- cmp [%u] %*phN\n",
p->index, p->skid->len, p->skid->data);
if (asymmetric_key_id_same(p->skid, auth))
goto found_issuer;
}
}
/* We didn't find the root of this chain */
pr_debug("- top\n");
return 0;
found_issuer_check_skid:
/* We matched issuer + serialNumber, but if there's an
* authKeyId.keyId, that must match the CA subjKeyId also.
*/
if (x509->akid_skid &&
!asymmetric_key_id_same(p->skid, x509->akid_skid)) {
pr_warn("Sig %u: X.509 chain contains auth-skid nonmatch (%u->%u)\n",
sinfo->index, x509->index, p->index);
return -EKEYREJECTED;
}
found_issuer:
pr_debug("- subject %s\n", p->subject);
if (p->seen) {
pr_warn("Sig %u: X.509 chain contains loop\n",
sinfo->index);
return 0;
}
ret = x509_check_signature(p->pub, x509);
if (ret < 0)
return ret;
x509->signer = p;
if (x509 == p) {
pr_debug("- self-signed\n");
return 0;
}
x509 = p;
might_sleep();
}
maybe_missing_crypto_in_x509:
/* Just prune the certificate chain at this point if we lack some
* crypto module to go further. Note, however, we don't want to set
* sinfo->missing_crypto as the signed info block may still be
* validatable against an X.509 cert lower in the chain that we have a
* trusted copy of.
*/
if (ret == -ENOPKG)
return 0;
return ret;
}
/**
* x509_request_asymmetric_key - Request a key by X.509 certificate params.
* @keyring: The keys to search.
* @id: The issuer & serialNumber to look for or NULL.
* @skid: The subjectKeyIdentifier to look for or NULL.
* @partial: Use partial match if true, exact if false.
*
* Find a key in the given keyring by identifier. The preferred identifier is
* the issuer + serialNumber and the fallback identifier is the
* subjectKeyIdentifier. If both are given, the lookup is by the former, but
* the latter must also match.
*/
struct key *x509_request_asymmetric_key(struct key *keyring,
const struct asymmetric_key_id *id,
const struct asymmetric_key_id *skid,
bool partial)
{
struct key *key;
key_ref_t ref;
const char *lookup;
char *req, *p;
int len;
if (id) {
lookup = id->data;
len = id->len;
} else {
lookup = skid->data;
len = skid->len;
}
/* Construct an identifier "id:<keyid>". */
p = req = kmalloc(2 + 1 + len * 2 + 1, GFP_KERNEL);
if (!req)
return ERR_PTR(-ENOMEM);
if (partial) {
*p++ = 'i';
*p++ = 'd';
} else {
*p++ = 'e';
*p++ = 'x';
}
*p++ = ':';
p = bin2hex(p, lookup, len);
*p = 0;
pr_debug("Look up: \"%s\"\n", req);
ref = keyring_search(make_key_ref(keyring, 1),
&key_type_asymmetric, req);
if (IS_ERR(ref))
pr_debug("Request for key '%s' err %ld\n", req, PTR_ERR(ref));
kfree(req);
if (IS_ERR(ref)) {
switch (PTR_ERR(ref)) {
/* Hide some search errors */
case -EACCES:
case -ENOTDIR:
case -EAGAIN:
return ERR_PTR(-ENOKEY);
default:
return ERR_CAST(ref);
}
}
key = key_ref_to_ptr(ref);
if (id && skid) {
const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
if (!kids->id[1]) {
pr_debug("issuer+serial match, but expected SKID missing\n");
goto reject;
}
if (!asymmetric_key_id_same(skid, kids->id[1])) {
pr_debug("issuer+serial match, but SKID does not\n");
goto reject;
}
}
pr_devel("<==%s() = 0 [%x]\n", __func__, key_serial(key));
return key;
reject:
key_put(key);
return ERR_PTR(-EKEYREJECTED);
}