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danessl.c
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danessl.c
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/*
* Author: Viktor Dukhovni
* License: THIS CODE IS IN THE PUBLIC DOMAIN.
*/
#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <openssl/opensslv.h>
#include <openssl/err.h>
#include <openssl/crypto.h>
#include <openssl/safestack.h>
#include <openssl/objects.h>
#include <openssl/x509.h>
#include <openssl/x509v3.h>
#include <openssl/evp.h>
#include <openssl/bn.h>
#if OPENSSL_VERSION_NUMBER < 0x1000000fL
#error "OpenSSL 1.0.0 or higher required"
#endif
#if OPENSSL_VERSION_NUMBER < 0x10100000L
#define X509_up_ref(x) CRYPTO_add(&((x)->references), 1, CRYPTO_LOCK_X509)
#define X509_STORE_CTX_get0_cert(ctx) ((ctx)->cert)
#define X509_STORE_CTX_get0_untrusted(ctx) ((ctx)->untrusted)
#define X509_STORE_CTX_get0_chain(ctx) ((ctx)->chain)
#define X509_STORE_CTX_get_verify(ctx) ((ctx)->verify)
#define X509_STORE_CTX_get_verify_cb(ctx) ((ctx)->verify_cb)
#define X509_STORE_CTX_set0_verified_chain(ctx, xs) ((ctx)->chain = xs)
#define X509_STORE_CTX_set0_untrusted X509_STORE_CTX_set_chain
#define X509_STORE_CTX_set0_trusted_stack X509_STORE_CTX_trusted_stack
#define X509_STORE_CTX_set_verify(ctx, v) ((ctx)->verify = v)
#define X509_STORE_CTX_set_error_depth(ctx, d) ((ctx)->error_depth = d)
#define X509_STORE_CTX_set_current_cert(ctx, x) ((ctx)->current_cert = x)
#define ASN1_STRING_get0_data ASN1_STRING_data
#define X509_getm_notBefore X509_get_notBefore
#define X509_getm_notAfter X509_get_notAfter
#define CRYPTO_ONCE_STATIC_INIT 0
#define CRYPTO_THREAD_run_once run_once
typedef int CRYPTO_ONCE;
#endif
#if OPENSSL_VERSION_NUMBER < 0x10002000L
#warning "OpenSSL 1.0.1 and earlier are EOL, upgrade to 1.0.2 or later"
#define SSL_is_server(s) ((s)->server)
#define SSL_get0_param(s) ((s)->param)
#endif
#include "danessl.h"
#define DANESSL_F_ADD_SKID 100
#define DANESSL_F_ADD_TLSA 101
#define DANESSL_F_CHECK_END_ENTITY 102
#define DANESSL_F_CTX_INIT 103
#define DANESSL_F_DANESSL_VERIFY_CHAIN 113
#define DANESSL_F_GROW_CHAIN 104
#define DANESSL_F_INIT 105
#define DANESSL_F_LIBRARY_INIT 106
#define DANESSL_F_LIST_ALLOC 107
#define DANESSL_F_MATCH 108
#define DANESSL_F_ADD_EXT 109
#define DANESSL_F_SET_TRUST_ANCHOR 110
#define DANESSL_F_VERIFY_CERT 111
#define DANESSL_F_WRAP_CERT 112
#define DANESSL_R_BAD_CERT 100
#define DANESSL_R_BAD_CERT_PKEY 101
#define DANESSL_R_BAD_DATA_LENGTH 102
#define DANESSL_R_BAD_DIGEST 103
#define DANESSL_R_BAD_NULL_DATA 104
#define DANESSL_R_BAD_PKEY 105
#define DANESSL_R_BAD_SELECTOR 106
#define DANESSL_R_BAD_USAGE 107
#define DANESSL_R_INIT 108
#define DANESSL_R_LIBRARY_INIT 109
#define DANESSL_R_NOSIGN_KEY 110
#define DANESSL_R_SCTX_INIT 111
#define DANESSL_R_SUPPORT 112
#ifndef OPENSSL_NO_ERR
#define DANESSL_F_PLACEHOLDER 0 /* FIRST! Value TBD */
static ERR_STRING_DATA dane_str_functs[] = {
{DANESSL_F_PLACEHOLDER, "DANE library"}, /* FIRST!!! */
{DANESSL_F_ADD_SKID, "add_skid"},
{DANESSL_F_ADD_TLSA, "DANESSL_add_tlsa"},
{DANESSL_F_CHECK_END_ENTITY, "check_end_entity"},
{DANESSL_F_CTX_INIT, "DANESSL_CTX_init"},
{DANESSL_F_GROW_CHAIN, "grow_chain"},
{DANESSL_F_INIT, "DANESSL_init"},
{DANESSL_F_LIBRARY_INIT, "DANESSL_library_init"},
{DANESSL_F_LIST_ALLOC, "list_alloc"},
{DANESSL_F_MATCH, "match"},
{DANESSL_F_ADD_EXT, "add_ext"},
{DANESSL_F_SET_TRUST_ANCHOR, "set_trust_anchor"},
{DANESSL_F_VERIFY_CERT, "verify_cert"},
{DANESSL_F_WRAP_CERT, "wrap_cert"},
{0, NULL}
};
static ERR_STRING_DATA dane_str_reasons[] = {
{DANESSL_R_BAD_CERT, "Bad TLSA record certificate"},
{DANESSL_R_BAD_CERT_PKEY, "Bad TLSA record certificate public key"},
{DANESSL_R_BAD_DATA_LENGTH, "Bad TLSA record digest length"},
{DANESSL_R_BAD_DIGEST, "Bad TLSA record digest"},
{DANESSL_R_BAD_NULL_DATA, "Bad TLSA record null data"},
{DANESSL_R_BAD_PKEY, "Bad TLSA record public key"},
{DANESSL_R_BAD_SELECTOR, "Bad TLSA record selector"},
{DANESSL_R_BAD_USAGE, "Bad TLSA record usage"},
{DANESSL_R_INIT, "DANESSL_init() required"},
{DANESSL_R_LIBRARY_INIT, "DANESSL_library_init() required"},
{DANESSL_R_NOSIGN_KEY, "Certificate usage 2 requires EC support"},
{DANESSL_R_SCTX_INIT, "DANESSL_CTX_init() required"},
{DANESSL_R_SUPPORT, "DANE library features not supported"},
{0, NULL}
};
#endif
#define DANEerr(f, r) ERR_PUT_error(err_lib_dane, (f), (r), __FILE__, __LINE__)
static int err_lib_dane = -1;
static int dane_idx = -1;
#ifdef X509_V_FLAG_PARTIAL_CHAIN /* OpenSSL >= 1.0.2 */
static int wrap_to_root = 0;
#else
static int wrap_to_root = 1;
#endif
static void (*cert_free)(void *) = (void (*)(void *)) X509_free;
static void (*pkey_free)(void *) = (void (*)(void *)) EVP_PKEY_free;
typedef struct dane_list {
struct dane_list *next;
void *value;
} *dane_list;
#define LINSERT(h, e) do { (e)->next = (h); (h) = (e); } while (0)
typedef struct DANE_HOST_LIST {
struct DANE_HOST_LIST *next;
char *value;
} *DANE_HOST_LIST;
typedef struct dane_data {
size_t datalen;
unsigned char data[0];
} *dane_data;
typedef struct DANE_DATA_LIST {
struct DANE_DATA_LIST *next;
dane_data value;
} *DANE_DATA_LIST;
typedef struct dane_mtype {
int mdlen;
const EVP_MD *md;
DANE_DATA_LIST data;
} *dane_mtype;
typedef struct DANE_MTYPE_LIST {
struct DANE_MTYPE_LIST *next;
dane_mtype value;
} *DANE_MTYPE_LIST;
typedef struct dane_selector {
uint8_t selector;
DANE_MTYPE_LIST mtype;
} *dane_selector;
typedef struct DANE_SELECTOR_LIST {
struct DANE_SELECTOR_LIST *next;
dane_selector value;
} *DANE_SELECTOR_LIST;
typedef struct DANE_PKEY_LIST {
struct DANE_PKEY_LIST *next;
EVP_PKEY *value;
} *DANE_PKEY_LIST;
typedef struct DANE_CERT_LIST {
struct DANE_CERT_LIST *next;
X509 *value;
} *DANE_CERT_LIST;
typedef struct DANESSL {
int (*verify)(X509_STORE_CTX *);
STACK_OF(X509) *roots;
STACK_OF(X509) *chain;
X509 *match; /* Matched cert */
const char *thost; /* TLSA base domain */
char *mhost; /* Matched peer name */
DANE_PKEY_LIST pkeys;
DANE_CERT_LIST certs;
DANE_HOST_LIST hosts;
DANE_SELECTOR_LIST selectors[DANESSL_USAGE_LAST + 1];
int depth;
int mdpth; /* Depth of matched cert */
int multi; /* Multi-label wildcards? */
int count; /* Number of TLSA records */
} DANESSL;
#ifndef X509_V_ERR_HOSTNAME_MISMATCH
#define X509_V_ERR_HOSTNAME_MISMATCH X509_V_ERR_APPLICATION_VERIFICATION
#endif
static int match(DANE_SELECTOR_LIST slist, X509 *cert, int depth)
{
int matched;
/*
* Note, set_trust_anchor() needs to know whether the match was for a
* pkey digest or a certificate digest. We return MATCHED_PKEY or
* MATCHED_CERT accordingly.
*/
#define MATCHED_CERT (DANESSL_SELECTOR_CERT + 1)
#define MATCHED_PKEY (DANESSL_SELECTOR_SPKI + 1)
/*
* Loop over each selector, mtype, and associated data element looking
* for a match.
*/
for (matched = 0; !matched && slist; slist = slist->next) {
DANE_MTYPE_LIST m;
unsigned char mdbuf[EVP_MAX_MD_SIZE];
unsigned char *buf;
unsigned char *buf2;
unsigned int len;
/*
* Extract ASN.1 DER form of certificate or public key.
*/
switch (slist->value->selector) {
case DANESSL_SELECTOR_CERT:
len = i2d_X509(cert, NULL);
buf2 = buf = (unsigned char *) OPENSSL_malloc(len);
if (buf)
i2d_X509(cert, &buf2);
break;
case DANESSL_SELECTOR_SPKI:
len = i2d_X509_PUBKEY(X509_get_X509_PUBKEY(cert), NULL);
buf2 = buf = (unsigned char *) OPENSSL_malloc(len);
if (buf)
i2d_X509_PUBKEY(X509_get_X509_PUBKEY(cert), &buf2);
break;
}
if (buf == NULL) {
DANEerr(DANESSL_F_MATCH, ERR_R_MALLOC_FAILURE);
return 0;
}
OPENSSL_assert(buf2 - buf == len);
/*
* Loop over each mtype and data element
*/
for (m = slist->value->mtype; !matched && m; m = m->next) {
DANE_DATA_LIST d;
unsigned char *cmpbuf = buf;
unsigned int cmplen = len;
/*
* If it is a digest, compute the corresponding digest of the
* DER data for comparison, otherwise, use the full object.
*/
if (m->value->md) {
cmpbuf = mdbuf;
if (!EVP_Digest(buf, len, cmpbuf, &cmplen, m->value->md, 0))
matched = -1;
}
for (d = m->value->data; !matched && d; d = d->next)
if (cmplen == d->value->datalen &&
memcmp(cmpbuf, d->value->data, cmplen) == 0)
matched = slist->value->selector + 1;
}
OPENSSL_free(buf);
}
return matched;
}
static int add_ext(X509 *issuer, X509 *subject, int ext_nid, char *ext_val)
{
int ret = 0;
X509V3_CTX v3ctx;
X509_EXTENSION *ext;
X509V3_set_ctx(&v3ctx, issuer, subject, 0, 0, 0);
if ((ext = X509V3_EXT_conf_nid(0, &v3ctx, ext_nid, ext_val)) != 0) {
ret = X509_add_ext(subject, ext, -1);
X509_EXTENSION_free(ext);
}
if (ret == 0)
DANEerr(DANESSL_F_ADD_EXT, ERR_R_MALLOC_FAILURE);
return ret;
}
static int set_serial(X509 *cert, AUTHORITY_KEYID *akid, X509 *subject)
{
int ret = 0;
BIGNUM *bn;
if (akid && akid->serial)
return (X509_set_serialNumber(cert, akid->serial));
/*
* Add one to subject's serial to avoid collisions between TA serial and
* serial of signing root.
*/
if ((bn = ASN1_INTEGER_to_BN(X509_get_serialNumber(subject), 0)) != 0
&& BN_add_word(bn, 1)
&& BN_to_ASN1_INTEGER(bn, X509_get_serialNumber(cert)))
ret = 1;
if (bn)
BN_free(bn);
return ret;
}
static int add_akid(X509 *cert, AUTHORITY_KEYID *akid)
{
int nid = NID_authority_key_identifier;
ASN1_OCTET_STRING *id;
unsigned char c = 0;
int ret = 0;
/*
* 0 will never be our subject keyid from a SHA-1 hash, but it could be
* our subject keyid if forced from child's akid. If so, set our
* authority keyid to 1. This way we are never self-signed, and thus
* exempt from any potential (off by default for now in OpenSSL)
* self-signature checks!
*/
id = (akid && akid->keyid) ? akid->keyid : 0;
if (id && ASN1_STRING_length(id) == 1 && *ASN1_STRING_get0_data(id) == c)
c = 1;
if ((akid = AUTHORITY_KEYID_new()) != 0
&& (akid->keyid = ASN1_OCTET_STRING_new()) != 0
&& ASN1_OCTET_STRING_set(akid->keyid, (void *) &c, 1)
&& X509_add1_ext_i2d(cert, nid, akid, 0, X509V3_ADD_APPEND))
ret = 1;
if (akid)
AUTHORITY_KEYID_free(akid);
return ret;
}
static int add_skid(X509 *cert, AUTHORITY_KEYID *akid)
{
int nid = NID_subject_key_identifier;
if (!akid || !akid->keyid)
return add_ext(0, cert, nid, "hash");
return X509_add1_ext_i2d(cert, nid, akid->keyid, 0, X509V3_ADD_APPEND) > 0;
}
static X509_NAME *akid_issuer_name(AUTHORITY_KEYID *akid)
{
if (akid && akid->issuer) {
int i;
GENERAL_NAMES *gens = akid->issuer;
for (i = 0; i < sk_GENERAL_NAME_num(gens); ++i) {
GENERAL_NAME *gn = sk_GENERAL_NAME_value(gens, i);
if (gn->type == GEN_DIRNAME)
return (gn->d.dirn);
}
}
return 0;
}
static int set_issuer_name(X509 *cert, AUTHORITY_KEYID *akid, X509_NAME *subj)
{
X509_NAME *name = akid_issuer_name(akid);
/*
* If subject's akid specifies an authority key identifer issuer name, we
* must use that.
*/
if (name)
return X509_set_issuer_name(cert, name);
return X509_set_issuer_name(cert, subj);
}
static int grow_chain(DANESSL *dane, int trusted, X509 *cert)
{
STACK_OF(X509) **xs = trusted ? &dane->roots : &dane->chain;
static ASN1_OBJECT *serverAuth = 0;
#define UNTRUSTED 0
#define TRUSTED 1
if (trusted && serverAuth == 0 &&
(serverAuth = OBJ_nid2obj(NID_server_auth)) == 0) {
DANEerr(DANESSL_F_GROW_CHAIN, ERR_R_MALLOC_FAILURE);
return 0;
}
if (!*xs && (*xs = sk_X509_new_null()) == 0) {
DANEerr(DANESSL_F_GROW_CHAIN, ERR_R_MALLOC_FAILURE);
return 0;
}
if (cert) {
if (trusted && !X509_add1_trust_object(cert, serverAuth))
return 0;
X509_up_ref(cert);
if (!sk_X509_push(*xs, cert)) {
X509_free(cert);
DANEerr(DANESSL_F_GROW_CHAIN, ERR_R_MALLOC_FAILURE);
return 0;
}
}
return 1;
}
static int wrap_issuer(
DANESSL *dane,
EVP_PKEY *key,
X509 *subject,
int depth,
int top
)
{
int ret = 1;
X509 *cert = 0;
AUTHORITY_KEYID *akid;
X509_NAME *name = X509_get_issuer_name(subject);
EVP_PKEY *newkey = key ? key : X509_get_pubkey(subject);
#define WRAP_MID 0 /* Ensure intermediate. */
#define WRAP_TOP 1 /* Ensure self-signed. */
if (name == 0 || newkey == 0 || (cert = X509_new()) == 0)
return 0;
/*
* Record the depth of the trust-anchor certificate.
*/
if (dane->depth < 0)
dane->depth = depth + 1;
/*
* XXX: Uncaught error condition:
*
* The return value is NULL both when the extension is missing, and when
* OpenSSL rans out of memory while parsing the extension.
*/
ERR_clear_error();
akid = X509_get_ext_d2i(subject, NID_authority_key_identifier, 0, 0);
/* XXX: Should we peek at the error stack here??? */
/*
* If top is true generate a self-issued root CA, otherwise an
* intermediate CA and possibly its self-signed issuer.
*
* CA cert valid for +/- 30 days
*/
if (!X509_set_version(cert, 2)
|| !set_serial(cert, akid, subject)
|| !set_issuer_name(cert, akid, name)
|| !X509_gmtime_adj(X509_getm_notBefore(cert), -30 * 86400L)
|| !X509_gmtime_adj(X509_getm_notAfter(cert), 30 * 86400L)
|| !X509_set_subject_name(cert, name)
|| !X509_set_pubkey(cert, newkey)
|| !add_ext(0, cert, NID_basic_constraints, "CA:TRUE")
|| (!top && !add_akid(cert, akid))
|| !add_skid(cert, akid)
|| (!top && wrap_to_root &&
!wrap_issuer(dane, newkey, cert, depth, WRAP_TOP))) {
ret = 0;
}
if (akid)
AUTHORITY_KEYID_free(akid);
if (!key)
EVP_PKEY_free(newkey);
if (ret) {
if (!top && wrap_to_root)
ret = grow_chain(dane, UNTRUSTED, cert);
else
ret = grow_chain(dane, TRUSTED, cert);
}
if (cert)
X509_free(cert);
return ret;
}
static int wrap_cert(DANESSL *dane, X509 *tacert, int depth)
{
if (dane->depth < 0)
dane->depth = depth + 1;
/*
* If the TA certificate is self-issued, or need not be, use it directly.
* Otherwise, synthesize requisuite ancestors.
*/
if (!wrap_to_root
|| X509_check_issued(tacert, tacert) == X509_V_OK)
return grow_chain(dane, TRUSTED, tacert);
if (wrap_issuer(dane, 0, tacert, depth, WRAP_MID))
return grow_chain(dane, UNTRUSTED, tacert);
return 0;
}
static int ta_signed(DANESSL *dane, X509 *cert, int depth)
{
DANE_CERT_LIST x;
DANE_PKEY_LIST k;
EVP_PKEY *pk;
int done = 0;
/*
* First check whether issued and signed by a TA cert, this is cheaper
* than the bare-public key checks below, since we can determine whether
* the candidate TA certificate issued the certificate to be checked
* first (name comparisons), before we bother with signature checks
* (public key operations).
*/
for (x = dane->certs; !done && x; x = x->next) {
if (X509_check_issued(x->value, cert) == X509_V_OK) {
if ((pk = X509_get_pubkey(x->value)) == 0) {
/*
* The cert originally contained a valid pkey, which does
* not just vanish, so this is most likely a memory error.
*/
done = -1;
break;
}
/* Check signature, since some other TA may work if not this. */
if (X509_verify(cert, pk) > 0)
done = wrap_cert(dane, x->value, depth) ? 1 : -1;
EVP_PKEY_free(pk);
}
}
/*
* With bare TA public keys, we can't check whether the trust chain is
* issued by the key, but we can determine whether it is signed by the
* key, so we go with that.
*
* Ideally, the corresponding certificate was presented in the chain, and we
* matched it by its public key digest one level up. This code is here
* to handle adverse conditions imposed by sloppy administrators of
* receiving systems with poorly constructed chains.
*
* We'd like to optimize out keys that should not match when the cert's
* authority key id does not match the key id of this key computed via
* the RFC keyid algorithm (SHA-1 digest of public key bit-string sans
* ASN1 tag and length thus also excluding the unused bits field that is
* logically part of the length). However, some CAs have a non-standard
* authority keyid, so we lose. Too bad.
*
* This may push errors onto the stack when the certificate signature is
* not of the right type or length, throw these away,
*/
for (k = dane->pkeys; !done && k; k = k->next)
if (X509_verify(cert, k->value) > 0)
done = wrap_issuer(dane, k->value, cert, depth, WRAP_MID) ? 1 : -1;
else
ERR_clear_error();
return done;
}
static int set_trust_anchor(X509_STORE_CTX *ctx, DANESSL *dane, X509 *cert)
{
int matched = 0;
int n;
int i;
int depth = 0;
EVP_PKEY *takey;
X509 *ca;
STACK_OF(X509) *in = X509_STORE_CTX_get0_untrusted(ctx);
if (!grow_chain(dane, UNTRUSTED, 0))
return -1;
/*
* Accept a degenerate case: depth 0 self-signed trust-anchor.
*/
if (X509_check_issued(cert, cert) == X509_V_OK) {
dane->depth = 0;
matched = match(dane->selectors[DANESSL_USAGE_DANE_TA], cert, 0);
if (matched > 0 && !grow_chain(dane, TRUSTED, cert))
matched = -1;
return matched;
}
/* Make a shallow copy of the input untrusted chain. */
if ((in = sk_X509_dup(in)) == 0) {
DANEerr(DANESSL_F_SET_TRUST_ANCHOR, ERR_R_MALLOC_FAILURE);
return -1;
}
/*
* At each iteration we consume the issuer of the current cert. This
* reduces the length of the "in" chain by one. If no issuer is found,
* we are done. We also stop when a certificate matches a TA in the
* peer's TLSA RRset.
*
* Caller ensures that the initial certificate is not self-signed.
*/
for (n = sk_X509_num(in); n > 0; --n, ++depth) {
for (i = 0; i < n; ++i)
if (X509_check_issued(sk_X509_value(in, i), cert) == X509_V_OK)
break;
/*
* Final untrusted element with no issuer in the peer's chain, it may
* however be signed by a pkey or cert obtained via a TLSA RR.
*/
if (i == n)
break;
/* Peer's chain contains an issuer ca. */
ca = sk_X509_delete(in, i);
/* If not a trust anchor, record untrusted ca and continue. */
if ((matched = match(dane->selectors[DANESSL_USAGE_DANE_TA], ca,
depth + 1)) == 0) {
if (grow_chain(dane, UNTRUSTED, ca)) {
if (X509_check_issued(ca, ca) != X509_V_OK) {
/* Restart with issuer as subject */
cert = ca;
continue;
}
/* Final self-signed element, skip ta_signed() check. */
cert = 0;
} else
matched = -1;
} else if (matched == MATCHED_CERT) {
if (!wrap_cert(dane, ca, depth))
matched = -1;
} else if (matched == MATCHED_PKEY) {
if ((takey = X509_get_pubkey(ca)) == 0)
DANEerr(DANESSL_F_SET_TRUST_ANCHOR, ERR_R_MALLOC_FAILURE);
if (takey == 0 ||
!wrap_issuer(dane, takey, cert, depth, WRAP_MID))
matched = -1;
if (takey)
EVP_PKEY_free(takey);
}
break;
}
/* Shallow free the duplicated input untrusted chain. */
sk_X509_free(in);
/*
* When the loop exits, if "cert" is set, it is not self-signed and has
* no issuer in the chain, we check for a possible signature via a DNS
* obtained TA cert or public key.
*/
if (matched == 0 && cert)
matched = ta_signed(dane, cert, depth);
return matched;
}
static int check_end_entity(X509_STORE_CTX *ctx, DANESSL *dane, X509 *cert)
{
int matched;
matched = match(dane->selectors[DANESSL_USAGE_DANE_EE], cert, 0);
if (matched > 0) {
dane->mdpth = 0;
dane->match = cert;
X509_up_ref(cert);
if (X509_STORE_CTX_get0_chain(ctx) == 0) {
STACK_OF(X509) *chain = sk_X509_new_null();
if (chain && sk_X509_push(chain, cert)) {
X509_up_ref(cert);
X509_STORE_CTX_set0_verified_chain(ctx, chain);
} else {
if (chain)
sk_X509_free(chain);
DANEerr(DANESSL_F_CHECK_END_ENTITY, ERR_R_MALLOC_FAILURE);
return -1;
}
}
}
return matched;
}
static int match_name(const char *certid, DANESSL *dane)
{
int multi = dane->multi;
DANE_HOST_LIST hosts = dane->hosts;
for (/* NOP */; hosts; hosts = hosts->next) {
int match_subdomain = 0;
const char *domain = hosts->value;
const char *parent;
int idlen;
int domlen;
if (*domain == '.' && domain[1] != '\0') {
++domain;
match_subdomain = 1;
}
/*
* Sub-domain match: certid is any sub-domain of hostname.
*/
if (match_subdomain) {
if ((idlen = strlen(certid)) > (domlen = strlen(domain)) + 1
&& certid[idlen - domlen - 1] == '.'
&& !strcasecmp(certid + (idlen - domlen), domain))
return 1;
else
continue;
}
/*
* Exact match and initial "*" match. The initial "*" in a certid
* matches one (if multi is false) or more hostname components under
* the condition that the certid contains multiple hostname components.
*/
if (!strcasecmp(certid, domain)
|| (certid[0] == '*' && certid[1] == '.' && certid[2] != 0
&& (parent = strchr(domain, '.')) != 0
&& (idlen = strlen(certid + 1)) <= (domlen = strlen(parent))
&& strcasecmp(multi ? parent + domlen - idlen : parent,
certid + 1) == 0))
return 1;
}
return 0;
}
static const char *check_name(const char *name, int len)
{
register const char *cp = name + len;
while (len > 0 && *--cp == 0)
--len; /* Ignore trailing NULs */
if (len <= 0)
return 0;
for (cp = name; *cp; cp++) {
register char c = *cp;
if (!((c >= 'a' && c <= 'z') ||
(c >= '0' && c <= '9') ||
(c >= 'A' && c <= 'Z') ||
(c == '.' || c == '-') ||
(c == '*')))
return 0; /* Only LDH, '.' and '*' */
}
if (cp - name != len) /* Guard against internal NULs */
return 0;
return name;
}
static const char *parse_dns_name(const GENERAL_NAME *gn)
{
if (gn->type != GEN_DNS)
return 0;
if (ASN1_STRING_type(gn->d.ia5) != V_ASN1_IA5STRING)
return 0;
return check_name((const char *)ASN1_STRING_get0_data(gn->d.ia5),
ASN1_STRING_length(gn->d.ia5));
}
static char *parse_subject_name(X509 *cert)
{
X509_NAME *name = X509_get_subject_name(cert);
X509_NAME_ENTRY *entry;
ASN1_STRING *entry_str;
unsigned char *namebuf;
int nid = NID_commonName;
int len;
int i;
if (name == 0 || (i = X509_NAME_get_index_by_NID(name, nid, -1)) < 0)
return 0;
if ((entry = X509_NAME_get_entry(name, i)) == 0)
return 0;
if ((entry_str = X509_NAME_ENTRY_get_data(entry)) == 0)
return 0;
if ((len = ASN1_STRING_to_UTF8(&namebuf, entry_str)) < 0)
return 0;
if (len <= 0 || check_name((char *) namebuf, len) == 0) {
OPENSSL_free(namebuf);
return 0;
}
return (char *) namebuf;
}
static int name_check(DANESSL *dane, X509 *cert)
{
int matched = 0;
int got_altname = 0;
GENERAL_NAMES *gens;
gens = X509_get_ext_d2i(cert, NID_subject_alt_name, 0, 0);
if (gens) {
int n = sk_GENERAL_NAME_num(gens);
int i;
for (i = 0; i < n; ++i) {
const GENERAL_NAME *gn = sk_GENERAL_NAME_value(gens, i);
const char *certid;
if (gn->type != GEN_DNS)
continue;
got_altname = 1;
certid = parse_dns_name(gn);
if (certid && *certid) {
if ((matched = match_name(certid, dane)) == 0)
continue;
if ((dane->mhost = OPENSSL_strdup(certid)) == 0)
matched = -1;
break;
}
}
GENERAL_NAMES_free(gens);
}
/*
* XXX: Should the subjectName be skipped when *any* altnames are present,
* or only when DNS altnames are present?
*/
if (got_altname == 0) {
char *certid = parse_subject_name(cert);
if (certid != 0 && *certid
&& (matched = match_name(certid, dane)) != 0)
dane->mhost = OPENSSL_strdup(certid);
if (certid)
OPENSSL_free(certid);
}
return matched;
}
static int verify_chain(X509_STORE_CTX *ctx)
{
DANE_SELECTOR_LIST issuer_rrs;
DANE_SELECTOR_LIST leaf_rrs;
int (*cb)(int, X509_STORE_CTX *) = X509_STORE_CTX_get_verify_cb(ctx);
int ssl_idx = SSL_get_ex_data_X509_STORE_CTX_idx();
SSL *ssl = X509_STORE_CTX_get_ex_data(ctx, ssl_idx);
DANESSL *dane = SSL_get_ex_data(ssl, dane_idx);
X509 *cert = X509_STORE_CTX_get0_cert(ctx);
STACK_OF(X509) *chain = X509_STORE_CTX_get0_chain(ctx);
int chain_length = sk_X509_num(chain);
int matched = 0;
issuer_rrs = dane->selectors[DANESSL_USAGE_PKIX_TA];
leaf_rrs = dane->selectors[DANESSL_USAGE_PKIX_EE];
/* Restore OpenSSL's internal_verify() as the signature check function */
X509_STORE_CTX_set_verify(ctx, dane->verify);
if ((matched = name_check(dane, cert)) < 0) {
X509_STORE_CTX_set_error(ctx, X509_V_ERR_OUT_OF_MEM);
return 0;
}
if (!matched) {
X509_STORE_CTX_set_error_depth(ctx, 0);
X509_STORE_CTX_set_current_cert(ctx, cert);
X509_STORE_CTX_set_error(ctx, X509_V_ERR_HOSTNAME_MISMATCH);
if (!cb(0, ctx))
return 0;
}
matched = 0;
/*
* Satisfy at least one usage 0 or 1 constraint, unless we've already
* matched a usage 2 trust anchor.
*
* XXX: internal_verify() doesn't callback with top certs that are not
* self-issued. This is fixed in OpenSSL 1.1.0.
*/
if (dane->roots && sk_X509_num(dane->roots)) {
X509 *top = sk_X509_value(chain, dane->depth);
dane->mdpth = dane->depth;
dane->match = top;
X509_up_ref(top);
#if OPENSSL_VERSION_NUMBER < 0x10100000L
if (X509_check_issued(top, top) != X509_V_OK) {
X509_STORE_CTX_set_error_depth(ctx, dane->depth);
X509_STORE_CTX_set_current_cert(ctx, top);
if (!cb(1, ctx))
return 0;
}
#endif
/* Pop synthetic trust-anchor ancestors off the chain! */
while (--chain_length > dane->depth)
X509_free(sk_X509_pop(chain));
} else {
int n = 0;
X509 *xn = cert;
/*
* Check for an EE match, then a CA match at depths > 0, and
* finally, if the EE cert is self-issued, for a depth 0 CA match.
*/
if (leaf_rrs)
matched = match(leaf_rrs, xn, 0);
if (!matched && issuer_rrs) {
for (n = chain_length-1; !matched && n >= 0; --n) {
xn = sk_X509_value(chain, n);
if (n > 0 || X509_check_issued(xn, xn) == X509_V_OK)
matched = match(issuer_rrs, xn, n);
}
}
if (matched < 0) {
X509_STORE_CTX_set_error(ctx, X509_V_ERR_OUT_OF_MEM);
return 0;
}
if (!matched) {
X509_STORE_CTX_set_current_cert(ctx, cert);
X509_STORE_CTX_set_error_depth(ctx, 0);
X509_STORE_CTX_set_error(ctx, X509_V_ERR_CERT_UNTRUSTED);
if (!cb(0, ctx))
return 0;
} else {
dane->mdpth = n;
dane->match = xn;
X509_up_ref(xn);
}
}
/* Tail recurse into OpenSSL's internal_verify */
return dane->verify(ctx);
}
static void dane_reset(DANESSL *dane)
{
dane->depth = -1;
if (dane->mhost) {
OPENSSL_free(dane->mhost);
dane->mhost = 0;
}
if (dane->roots) {
sk_X509_pop_free(dane->roots, X509_free);
dane->roots = 0;
}
if (dane->chain) {
sk_X509_pop_free(dane->chain, X509_free);
dane->chain = 0;
}
if (dane->match) {
X509_free(dane->match);
dane->match = 0;
}
dane->mdpth = -1;
}
static
int verify_cert(X509_STORE_CTX *ctx, void *unused_ctx)
{
static int ssl_idx = -1;
SSL *ssl;
DANESSL *dane;
int (*cb)(int, X509_STORE_CTX *) = X509_STORE_CTX_get_verify_cb(ctx);
X509 *cert = X509_STORE_CTX_get0_cert(ctx);
int matched;
if (ssl_idx < 0)
ssl_idx = SSL_get_ex_data_X509_STORE_CTX_idx();
if (dane_idx < 0) {
DANEerr(DANESSL_F_VERIFY_CERT, ERR_R_MALLOC_FAILURE);
return -1;
}
ssl = X509_STORE_CTX_get_ex_data(ctx, ssl_idx);
if ((dane = SSL_get_ex_data(ssl, dane_idx)) == 0 || cert == 0)
return X509_verify_cert(ctx);
/* Reset for verification of a new chain, perhaps a renegotiation. */
dane_reset(dane);
if (dane->selectors[DANESSL_USAGE_DANE_EE]) {
if ((matched = check_end_entity(ctx, dane, cert)) > 0) {
X509_STORE_CTX_set_error_depth(ctx, 0);
X509_STORE_CTX_set_current_cert(ctx, cert);
return cb(1, ctx);
}
if (matched < 0) {
X509_STORE_CTX_set_error(ctx, X509_V_ERR_OUT_OF_MEM);
return -1;
}
/* Fail now, if all we have is DANE-EE TLSA records */
if (!matched
&& !dane->selectors[DANESSL_USAGE_DANE_TA]
&& !dane->selectors[DANESSL_USAGE_PKIX_EE]
&& !dane->selectors[DANESSL_USAGE_PKIX_TA]) {
X509_STORE_CTX_set_current_cert(ctx, cert);
X509_STORE_CTX_set_error_depth(ctx, 0);
X509_STORE_CTX_set_error(ctx, X509_V_ERR_CERT_UNTRUSTED);
return cb(0, ctx);
}
}