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openssl/crypto/x509/v3_purp.c
Tomas Mraz 67ecd65cc4 Rename check_chain_extensions to check_chain 
The function does much more than just checking extensions.

Reviewed-by: David von Oheimb <david.von.oheimb@siemens.com>
Reviewed-by: Nicola Tuveri <nic.tuv@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/12683)
2020-09-17 17:15:15 +02:00

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/*
* Copyright 1999-2020 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <stdio.h>
#include "internal/cryptlib.h"
#include "internal/numbers.h"
#include <openssl/x509v3.h>
#include <openssl/x509_vfy.h>
#include "crypto/x509.h"
#include "internal/tsan_assist.h"
#include "x509_local.h"
static int check_ssl_ca(const X509 *x);
static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
int ca);
static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x,
int ca);
static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x,
int ca);
static int purpose_smime(const X509 *x, int ca);
static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x,
int ca);
static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x,
int ca);
static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
int ca);
static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
int ca);
static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca);
static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca);
static int xp_cmp(const X509_PURPOSE *const *a, const X509_PURPOSE *const *b);
static void xptable_free(X509_PURPOSE *p);
static X509_PURPOSE xstandard[] = {
{X509_PURPOSE_SSL_CLIENT, X509_TRUST_SSL_CLIENT, 0,
check_purpose_ssl_client, "SSL client", "sslclient", NULL},
{X509_PURPOSE_SSL_SERVER, X509_TRUST_SSL_SERVER, 0,
check_purpose_ssl_server, "SSL server", "sslserver", NULL},
{X509_PURPOSE_NS_SSL_SERVER, X509_TRUST_SSL_SERVER, 0,
check_purpose_ns_ssl_server, "Netscape SSL server", "nssslserver", NULL},
{X509_PURPOSE_SMIME_SIGN, X509_TRUST_EMAIL, 0, check_purpose_smime_sign,
"S/MIME signing", "smimesign", NULL},
{X509_PURPOSE_SMIME_ENCRYPT, X509_TRUST_EMAIL, 0,
check_purpose_smime_encrypt, "S/MIME encryption", "smimeencrypt", NULL},
{X509_PURPOSE_CRL_SIGN, X509_TRUST_COMPAT, 0, check_purpose_crl_sign,
"CRL signing", "crlsign", NULL},
{X509_PURPOSE_ANY, X509_TRUST_DEFAULT, 0, no_check, "Any Purpose", "any",
NULL},
{X509_PURPOSE_OCSP_HELPER, X509_TRUST_COMPAT, 0, ocsp_helper,
"OCSP helper", "ocsphelper", NULL},
{X509_PURPOSE_TIMESTAMP_SIGN, X509_TRUST_TSA, 0,
check_purpose_timestamp_sign, "Time Stamp signing", "timestampsign",
NULL},
};
#define X509_PURPOSE_COUNT OSSL_NELEM(xstandard)
static STACK_OF(X509_PURPOSE) *xptable = NULL;
static int xp_cmp(const X509_PURPOSE *const *a, const X509_PURPOSE *const *b)
{
return (*a)->purpose - (*b)->purpose;
}
/*
* As much as I'd like to make X509_check_purpose use a "const" X509* I
* really can't because it does recalculate hashes and do other non-const
* things.
*/
int X509_check_purpose(X509 *x, int id, int ca)
{
int idx;
const X509_PURPOSE *pt;
if (!x509v3_cache_extensions(x))
return -1;
/* Return if side-effect only call */
if (id == -1)
return 1;
idx = X509_PURPOSE_get_by_id(id);
if (idx == -1)
return -1;
pt = X509_PURPOSE_get0(idx);
return pt->check_purpose(pt, x, ca);
}
int X509_PURPOSE_set(int *p, int purpose)
{
if (X509_PURPOSE_get_by_id(purpose) == -1) {
X509V3err(X509V3_F_X509_PURPOSE_SET, X509V3_R_INVALID_PURPOSE);
return 0;
}
*p = purpose;
return 1;
}
int X509_PURPOSE_get_count(void)
{
if (!xptable)
return X509_PURPOSE_COUNT;
return sk_X509_PURPOSE_num(xptable) + X509_PURPOSE_COUNT;
}
X509_PURPOSE *X509_PURPOSE_get0(int idx)
{
if (idx < 0)
return NULL;
if (idx < (int)X509_PURPOSE_COUNT)
return xstandard + idx;
return sk_X509_PURPOSE_value(xptable, idx - X509_PURPOSE_COUNT);
}
int X509_PURPOSE_get_by_sname(const char *sname)
{
int i;
X509_PURPOSE *xptmp;
for (i = 0; i < X509_PURPOSE_get_count(); i++) {
xptmp = X509_PURPOSE_get0(i);
if (strcmp(xptmp->sname, sname) == 0)
return i;
}
return -1;
}
int X509_PURPOSE_get_by_id(int purpose)
{
X509_PURPOSE tmp;
int idx;
if ((purpose >= X509_PURPOSE_MIN) && (purpose <= X509_PURPOSE_MAX))
return purpose - X509_PURPOSE_MIN;
if (xptable == NULL)
return -1;
tmp.purpose = purpose;
idx = sk_X509_PURPOSE_find(xptable, &tmp);
if (idx < 0)
return -1;
return idx + X509_PURPOSE_COUNT;
}
int X509_PURPOSE_add(int id, int trust, int flags,
int (*ck) (const X509_PURPOSE *, const X509 *, int),
const char *name, const char *sname, void *arg)
{
int idx;
X509_PURPOSE *ptmp;
/*
* This is set according to what we change: application can't set it
*/
flags &= ~X509_PURPOSE_DYNAMIC;
/* This will always be set for application modified trust entries */
flags |= X509_PURPOSE_DYNAMIC_NAME;
/* Get existing entry if any */
idx = X509_PURPOSE_get_by_id(id);
/* Need a new entry */
if (idx == -1) {
if ((ptmp = OPENSSL_malloc(sizeof(*ptmp))) == NULL) {
X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
return 0;
}
ptmp->flags = X509_PURPOSE_DYNAMIC;
} else
ptmp = X509_PURPOSE_get0(idx);
/* OPENSSL_free existing name if dynamic */
if (ptmp->flags & X509_PURPOSE_DYNAMIC_NAME) {
OPENSSL_free(ptmp->name);
OPENSSL_free(ptmp->sname);
}
/* dup supplied name */
ptmp->name = OPENSSL_strdup(name);
ptmp->sname = OPENSSL_strdup(sname);
if (ptmp->name == NULL|| ptmp->sname == NULL) {
X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
goto err;
}
/* Keep the dynamic flag of existing entry */
ptmp->flags &= X509_PURPOSE_DYNAMIC;
/* Set all other flags */
ptmp->flags |= flags;
ptmp->purpose = id;
ptmp->trust = trust;
ptmp->check_purpose = ck;
ptmp->usr_data = arg;
/* If its a new entry manage the dynamic table */
if (idx == -1) {
if (xptable == NULL
&& (xptable = sk_X509_PURPOSE_new(xp_cmp)) == NULL) {
X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
goto err;
}
if (!sk_X509_PURPOSE_push(xptable, ptmp)) {
X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
goto err;
}
}
return 1;
err:
if (idx == -1) {
OPENSSL_free(ptmp->name);
OPENSSL_free(ptmp->sname);
OPENSSL_free(ptmp);
}
return 0;
}
static void xptable_free(X509_PURPOSE *p)
{
if (p == NULL)
return;
if (p->flags & X509_PURPOSE_DYNAMIC) {
if (p->flags & X509_PURPOSE_DYNAMIC_NAME) {
OPENSSL_free(p->name);
OPENSSL_free(p->sname);
}
OPENSSL_free(p);
}
}
void X509_PURPOSE_cleanup(void)
{
sk_X509_PURPOSE_pop_free(xptable, xptable_free);
xptable = NULL;
}
int X509_PURPOSE_get_id(const X509_PURPOSE *xp)
{
return xp->purpose;
}
char *X509_PURPOSE_get0_name(const X509_PURPOSE *xp)
{
return xp->name;
}
char *X509_PURPOSE_get0_sname(const X509_PURPOSE *xp)
{
return xp->sname;
}
int X509_PURPOSE_get_trust(const X509_PURPOSE *xp)
{
return xp->trust;
}
static int nid_cmp(const int *a, const int *b)
{
return *a - *b;
}
DECLARE_OBJ_BSEARCH_CMP_FN(int, int, nid);
IMPLEMENT_OBJ_BSEARCH_CMP_FN(int, int, nid);
int X509_supported_extension(X509_EXTENSION *ex)
{
/*
* This table is a list of the NIDs of supported extensions: that is
* those which are used by the verify process. If an extension is
* critical and doesn't appear in this list then the verify process will
* normally reject the certificate. The list must be kept in numerical
* order because it will be searched using bsearch.
*/
static const int supported_nids[] = {
NID_netscape_cert_type, /* 71 */
NID_key_usage, /* 83 */
NID_subject_alt_name, /* 85 */
NID_basic_constraints, /* 87 */
NID_certificate_policies, /* 89 */
NID_crl_distribution_points, /* 103 */
NID_ext_key_usage, /* 126 */
#ifndef OPENSSL_NO_RFC3779
NID_sbgp_ipAddrBlock, /* 290 */
NID_sbgp_autonomousSysNum, /* 291 */
#endif
NID_policy_constraints, /* 401 */
NID_proxyCertInfo, /* 663 */
NID_name_constraints, /* 666 */
NID_policy_mappings, /* 747 */
NID_inhibit_any_policy /* 748 */
};
int ex_nid = OBJ_obj2nid(X509_EXTENSION_get_object(ex));
if (ex_nid == NID_undef)
return 0;
if (OBJ_bsearch_nid(&ex_nid, supported_nids, OSSL_NELEM(supported_nids)))
return 1;
return 0;
}
/* return 1 on success, 0 if x is invalid, -1 on (internal) error */
static int setup_dp(const X509 *x, DIST_POINT *dp)
{
const X509_NAME *iname = NULL;
int i;
if (dp->distpoint == NULL && sk_GENERAL_NAME_num(dp->CRLissuer) <= 0) {
X509err(0, X509_R_INVALID_DISTPOINT);
return 0;
}
if (dp->reasons != NULL) {
if (dp->reasons->length > 0)
dp->dp_reasons = dp->reasons->data[0];
if (dp->reasons->length > 1)
dp->dp_reasons |= (dp->reasons->data[1] << 8);
dp->dp_reasons &= CRLDP_ALL_REASONS;
} else {
dp->dp_reasons = CRLDP_ALL_REASONS;
}
if (dp->distpoint == NULL || dp->distpoint->type != 1)
return 1;
/* handle name fragment given by nameRelativeToCRLIssuer */
/*
* Note that the below way of determining iname is not really compliant
* with https://tools.ietf.org/html/rfc5280#section-4.2.1.13
* According to it, sk_GENERAL_NAME_num(dp->CRLissuer) MUST be <= 1
* and any CRLissuer could be of type different to GEN_DIRNAME.
*/
for (i = 0; i < sk_GENERAL_NAME_num(dp->CRLissuer); i++) {
GENERAL_NAME *gen = sk_GENERAL_NAME_value(dp->CRLissuer, i);
if (gen->type == GEN_DIRNAME) {
iname = gen->d.directoryName;
break;
}
}
if (iname == NULL)
iname = X509_get_issuer_name(x);
return DIST_POINT_set_dpname(dp->distpoint, iname) ? 1 : -1;
}
/* return 1 on success, 0 if x is invalid, -1 on (internal) error */
static int setup_crldp(X509 *x)
{
int i;
x->crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, &i, NULL);
if (x->crldp == NULL && i != -1)
return 0;
for (i = 0; i < sk_DIST_POINT_num(x->crldp); i++) {
int res = setup_dp(x, sk_DIST_POINT_value(x->crldp, i));
if (res < 1)
return res;
}
return 1;
}
/* Check that issuer public key algorithm matches subject signature algorithm */
static int check_sig_alg_match(const EVP_PKEY *pkey, const X509 *subject)
{
int pkey_nid;
if (pkey == NULL)
return X509_V_ERR_NO_ISSUER_PUBLIC_KEY;
if (OBJ_find_sigid_algs(OBJ_obj2nid(subject->cert_info.signature.algorithm),
NULL, &pkey_nid) == 0)
return X509_V_ERR_UNSUPPORTED_SIGNATURE_ALGORITHM;
if (EVP_PKEY_type(pkey_nid) != EVP_PKEY_base_id(pkey))
return X509_V_ERR_SIGNATURE_ALGORITHM_MISMATCH;
return X509_V_OK;
}
#define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
#define ku_reject(x, usage) \
(((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
#define xku_reject(x, usage) \
(((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
#define ns_reject(x, usage) \
(((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))
/*
* Cache info on various X.509v3 extensions and further derived information,
* e.g., if cert 'x' is self-issued, in x->ex_flags and other internal fields.
* X509_SIG_INFO_VALID is set in x->flags if x->siginf was filled successfully.
* Set EXFLAG_INVALID and return 0 in case the certificate is invalid.
*/
int x509v3_cache_extensions(X509 *x)
{
BASIC_CONSTRAINTS *bs;
PROXY_CERT_INFO_EXTENSION *pci;
ASN1_BIT_STRING *usage;
ASN1_BIT_STRING *ns;
EXTENDED_KEY_USAGE *extusage;
int i;
int res;
#ifdef tsan_ld_acq
/* fast lock-free check, see end of the function for details. */
if (tsan_ld_acq((TSAN_QUALIFIER int *)&x->ex_cached))
return (x->ex_flags & EXFLAG_INVALID) == 0;
#endif
CRYPTO_THREAD_write_lock(x->lock);
if (x->ex_flags & EXFLAG_SET) { /* cert has already been processed */
CRYPTO_THREAD_unlock(x->lock);
return (x->ex_flags & EXFLAG_INVALID) == 0;
}
ERR_set_mark();
/* Cache the SHA1 digest of the cert */
if (!X509_digest(x, EVP_sha1(), x->sha1_hash, NULL))
/*
* Note that the cert is marked invalid also on internal malloc failure
* or on failure of EVP_MD_fetch(), potentially called by X509_digest().
*/
x->ex_flags |= EXFLAG_INVALID;
/* V1 should mean no extensions ... */
if (X509_get_version(x) == 0)
x->ex_flags |= EXFLAG_V1;
/* Handle basic constraints */
x->ex_pathlen = -1;
if ((bs = X509_get_ext_d2i(x, NID_basic_constraints, &i, NULL)) != NULL) {
if (bs->ca)
x->ex_flags |= EXFLAG_CA;
if (bs->pathlen != NULL) {
/*
* the error case !bs->ca is checked by check_chain()
* in case ctx->param->flags & X509_V_FLAG_X509_STRICT
*/
if (bs->pathlen->type == V_ASN1_NEG_INTEGER) {
X509err(0, X509V3_R_NEGATIVE_PATHLEN);
x->ex_flags |= EXFLAG_INVALID;
} else {
x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
}
}
BASIC_CONSTRAINTS_free(bs);
x->ex_flags |= EXFLAG_BCONS;
} else if (i != -1) {
x->ex_flags |= EXFLAG_INVALID;
}
/* Handle proxy certificates */
if ((pci = X509_get_ext_d2i(x, NID_proxyCertInfo, &i, NULL)) != NULL) {
if (x->ex_flags & EXFLAG_CA
|| X509_get_ext_by_NID(x, NID_subject_alt_name, -1) >= 0
|| X509_get_ext_by_NID(x, NID_issuer_alt_name, -1) >= 0) {
x->ex_flags |= EXFLAG_INVALID;
}
if (pci->pcPathLengthConstraint != NULL)
x->ex_pcpathlen = ASN1_INTEGER_get(pci->pcPathLengthConstraint);
else
x->ex_pcpathlen = -1;
PROXY_CERT_INFO_EXTENSION_free(pci);
x->ex_flags |= EXFLAG_PROXY;
} else if (i != -1) {
x->ex_flags |= EXFLAG_INVALID;
}
/* Handle (basic) key usage */
if ((usage = X509_get_ext_d2i(x, NID_key_usage, &i, NULL)) != NULL) {
x->ex_kusage = 0;
if (usage->length > 0) {
x->ex_kusage = usage->data[0];
if (usage->length > 1)
x->ex_kusage |= usage->data[1] << 8;
}
x->ex_flags |= EXFLAG_KUSAGE;
ASN1_BIT_STRING_free(usage);
/* Check for empty key usage according to RFC 5280 section 4.2.1.3 */
if (x->ex_kusage == 0) {
X509err(0, X509V3_R_EMPTY_KEY_USAGE);
x->ex_flags |= EXFLAG_INVALID;
}
} else if (i != -1) {
x->ex_flags |= EXFLAG_INVALID;
}
/* Handle extended key usage */
x->ex_xkusage = 0;
if ((extusage = X509_get_ext_d2i(x, NID_ext_key_usage, &i, NULL)) != NULL) {
x->ex_flags |= EXFLAG_XKUSAGE;
for (i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
switch (OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage, i))) {
case NID_server_auth:
x->ex_xkusage |= XKU_SSL_SERVER;
break;
case NID_client_auth:
x->ex_xkusage |= XKU_SSL_CLIENT;
break;
case NID_email_protect:
x->ex_xkusage |= XKU_SMIME;
break;
case NID_code_sign:
x->ex_xkusage |= XKU_CODE_SIGN;
break;
case NID_ms_sgc:
case NID_ns_sgc:
x->ex_xkusage |= XKU_SGC;
break;
case NID_OCSP_sign:
x->ex_xkusage |= XKU_OCSP_SIGN;
break;
case NID_time_stamp:
x->ex_xkusage |= XKU_TIMESTAMP;
break;
case NID_dvcs:
x->ex_xkusage |= XKU_DVCS;
break;
case NID_anyExtendedKeyUsage:
x->ex_xkusage |= XKU_ANYEKU;
break;
default:
/* ignore unknown extended key usage */
break;
}
}
sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
} else if (i != -1) {
x->ex_flags |= EXFLAG_INVALID;
}
/* Handle legacy Netscape extension */
if ((ns = X509_get_ext_d2i(x, NID_netscape_cert_type, &i, NULL)) != NULL) {
if (ns->length > 0)
x->ex_nscert = ns->data[0];
else
x->ex_nscert = 0;
x->ex_flags |= EXFLAG_NSCERT;
ASN1_BIT_STRING_free(ns);
} else if (i != -1) {
x->ex_flags |= EXFLAG_INVALID;
}
/* Handle subject key identifier and issuer/authority key identifier */
x->skid = X509_get_ext_d2i(x, NID_subject_key_identifier, &i, NULL);
if (x->skid == NULL && i != -1)
x->ex_flags |= EXFLAG_INVALID;
x->akid = X509_get_ext_d2i(x, NID_authority_key_identifier, &i, NULL);
if (x->akid == NULL && i != -1)
x->ex_flags |= EXFLAG_INVALID;
/* Check if subject name matches issuer */
if (X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x)) == 0) {
x->ex_flags |= EXFLAG_SI; /* cert is self-issued */
if (X509_check_akid(x, x->akid) == X509_V_OK /* SKID matches AKID */
/* .. and the signature alg matches the PUBKEY alg: */
&& check_sig_alg_match(X509_get0_pubkey(x), x) == X509_V_OK)
x->ex_flags |= EXFLAG_SS; /* indicate self-signed */
/* This is very related to x509_likely_issued(x, x) == X509_V_OK */
}
/* Handle subject alternative names and various other extensions */
x->altname = X509_get_ext_d2i(x, NID_subject_alt_name, &i, NULL);
if (x->altname == NULL && i != -1)
x->ex_flags |= EXFLAG_INVALID;
x->nc = X509_get_ext_d2i(x, NID_name_constraints, &i, NULL);
if (x->nc == NULL && i != -1)
x->ex_flags |= EXFLAG_INVALID;
/* Handle CRL distribution point entries */
res = setup_crldp(x);
if (res == 0)
x->ex_flags |= EXFLAG_INVALID;
else if (res < 0)
goto err;
#ifndef OPENSSL_NO_RFC3779
x->rfc3779_addr = X509_get_ext_d2i(x, NID_sbgp_ipAddrBlock, &i, NULL);
if (x->rfc3779_addr == NULL && i != -1)
x->ex_flags |= EXFLAG_INVALID;
x->rfc3779_asid = X509_get_ext_d2i(x, NID_sbgp_autonomousSysNum, &i, NULL);
if (x->rfc3779_asid == NULL && i != -1)
x->ex_flags |= EXFLAG_INVALID;
#endif
for (i = 0; i < X509_get_ext_count(x); i++) {
X509_EXTENSION *ex = X509_get_ext(x, i);
int nid = OBJ_obj2nid(X509_EXTENSION_get_object(ex));
if (nid == NID_freshest_crl)
x->ex_flags |= EXFLAG_FRESHEST;
if (!X509_EXTENSION_get_critical(ex))
continue;
if (!X509_supported_extension(ex)) {
x->ex_flags |= EXFLAG_CRITICAL;
break;
}
switch (nid) {
case NID_basic_constraints:
x->ex_flags |= EXFLAG_BCONS_CRITICAL;
break;
case NID_authority_key_identifier:
x->ex_flags |= EXFLAG_AKID_CRITICAL;
break;
case NID_subject_key_identifier:
x->ex_flags |= EXFLAG_SKID_CRITICAL;
break;
case NID_subject_alt_name:
x->ex_flags |= EXFLAG_SAN_CRITICAL;
break;
default:
break;
}
}
/* Set x->siginf, ignoring errors due to unsupported algos */
(void)x509_init_sig_info(x);
x->ex_flags |= EXFLAG_SET; /* indicate that cert has been processed */
#ifdef tsan_st_rel
tsan_st_rel((TSAN_QUALIFIER int *)&x->ex_cached, 1);
/*
* Above store triggers fast lock-free check in the beginning of the
* function. But one has to ensure that the structure is "stable", i.e.
* all stores are visible on all processors. Hence the release fence.
*/
#endif
ERR_pop_to_mark();
if ((x->ex_flags & EXFLAG_INVALID) == 0) {
CRYPTO_THREAD_unlock(x->lock);
return 1;
}
X509err(0, X509V3_R_INVALID_CERTIFICATE);
err:
x->ex_flags |= EXFLAG_SET; /* indicate that cert has been processed */
CRYPTO_THREAD_unlock(x->lock);
return 0;
}
/*-
* CA checks common to all purposes
* return codes:
* 0 not a CA
* 1 is a CA
* 2 Only possible in older versions of openSSL when basicConstraints are absent
* new versions will not return this value. May be a CA
* 3 basicConstraints absent but self-signed V1.
* 4 basicConstraints absent but keyUsage present and keyCertSign asserted.
* 5 Netscape specific CA Flags present
*/
static int check_ca(const X509 *x)
{
/* keyUsage if present should allow cert signing */
if (ku_reject(x, KU_KEY_CERT_SIGN))
return 0;
if (x->ex_flags & EXFLAG_BCONS) {
if (x->ex_flags & EXFLAG_CA)
return 1;
/* If basicConstraints says not a CA then say so */
else
return 0;
} else {
/* we support V1 roots for... uh, I don't really know why. */
if ((x->ex_flags & V1_ROOT) == V1_ROOT)
return 3;
/*
* If key usage present it must have certSign so tolerate it
*/
else if (x->ex_flags & EXFLAG_KUSAGE)
return 4;
/* Older certificates could have Netscape-specific CA types */
else if (x->ex_flags & EXFLAG_NSCERT && x->ex_nscert & NS_ANY_CA)
return 5;
/* can this still be regarded a CA certificate? I doubt it */
return 0;
}
}
void X509_set_proxy_flag(X509 *x)
{
x->ex_flags |= EXFLAG_PROXY;
}
void X509_set_proxy_pathlen(X509 *x, long l)
{
x->ex_pcpathlen = l;
}
int X509_check_ca(X509 *x)
{
/* Note 0 normally means "not a CA" - but in this case means error. */
if (!x509v3_cache_extensions(x))
return 0;
return check_ca(x);
}
/* Check SSL CA: common checks for SSL client and server */
static int check_ssl_ca(const X509 *x)
{
int ca_ret;
ca_ret = check_ca(x);
if (!ca_ret)
return 0;
/* check nsCertType if present */
if (ca_ret != 5 || x->ex_nscert & NS_SSL_CA)
return ca_ret;
else
return 0;
}
static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
int ca)
{
if (xku_reject(x, XKU_SSL_CLIENT))
return 0;
if (ca)
return check_ssl_ca(x);
/* We need to do digital signatures or key agreement */
if (ku_reject(x, KU_DIGITAL_SIGNATURE | KU_KEY_AGREEMENT))
return 0;
/* nsCertType if present should allow SSL client use */
if (ns_reject(x, NS_SSL_CLIENT))
return 0;
return 1;
}
/*
* Key usage needed for TLS/SSL server: digital signature, encipherment or
* key agreement. The ssl code can check this more thoroughly for individual
* key types.
*/
#define KU_TLS \
KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT|KU_KEY_AGREEMENT
static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x,
int ca)
{
if (xku_reject(x, XKU_SSL_SERVER | XKU_SGC))
return 0;
if (ca)
return check_ssl_ca(x);
if (ns_reject(x, NS_SSL_SERVER))
return 0;
if (ku_reject(x, KU_TLS))
return 0;
return 1;
}
static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x,
int ca)
{
int ret;
ret = check_purpose_ssl_server(xp, x, ca);
if (!ret || ca)
return ret;
/* We need to encipher or Netscape complains */
if (ku_reject(x, KU_KEY_ENCIPHERMENT))
return 0;
return ret;
}
/* common S/MIME checks */
static int purpose_smime(const X509 *x, int ca)
{
if (xku_reject(x, XKU_SMIME))
return 0;
if (ca) {
int ca_ret;
ca_ret = check_ca(x);
if (!ca_ret)
return 0;
/* check nsCertType if present */
if (ca_ret != 5 || x->ex_nscert & NS_SMIME_CA)
return ca_ret;
else
return 0;
}
if (x->ex_flags & EXFLAG_NSCERT) {
if (x->ex_nscert & NS_SMIME)
return 1;
/* Workaround for some buggy certificates */
if (x->ex_nscert & NS_SSL_CLIENT)
return 2;
return 0;
}
return 1;
}
static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x,
int ca)
{
int ret;
ret = purpose_smime(x, ca);
if (!ret || ca)
return ret;
if (ku_reject(x, KU_DIGITAL_SIGNATURE | KU_NON_REPUDIATION))
return 0;
return ret;
}
static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x,
int ca)
{
int ret;
ret = purpose_smime(x, ca);
if (!ret || ca)
return ret;
if (ku_reject(x, KU_KEY_ENCIPHERMENT))
return 0;
return ret;
}
static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
int ca)
{
if (ca) {
int ca_ret;
if ((ca_ret = check_ca(x)) != 2)
return ca_ret;
else
return 0;
}
if (ku_reject(x, KU_CRL_SIGN))
return 0;
return 1;
}
/*
* OCSP helper: this is *not* a full OCSP check. It just checks that each CA
* is valid. Additional checks must be made on the chain.
*/
static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
{
/*
* Must be a valid CA. Should we really support the "I don't know" value
* (2)?
*/
if (ca)
return check_ca(x);
/* leaf certificate is checked in OCSP_verify() */
return 1;
}
static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
int ca)
{
int i_ext;
/* If ca is true we must return if this is a valid CA certificate. */
if (ca)
return check_ca(x);
/*
* Check the optional key usage field:
* if Key Usage is present, it must be one of digitalSignature
* and/or nonRepudiation (other values are not consistent and shall
* be rejected).
*/
if ((x->ex_flags & EXFLAG_KUSAGE)
&& ((x->ex_kusage & ~(KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE)) ||
!(x->ex_kusage & (KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE))))
return 0;
/* Only time stamp key usage is permitted and it's required. */
if (!(x->ex_flags & EXFLAG_XKUSAGE) || x->ex_xkusage != XKU_TIMESTAMP)
return 0;
/* Extended Key Usage MUST be critical */
i_ext = X509_get_ext_by_NID(x, NID_ext_key_usage, -1);
if (i_ext >= 0) {
X509_EXTENSION *ext = X509_get_ext((X509 *)x, i_ext);
if (!X509_EXTENSION_get_critical(ext))
return 0;
}
return 1;
}
static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
{
return 1;
}
/*-
* Various checks to see if one certificate potentially issued the second.
* This can be used to prune a set of possible issuer certificates which
* have been looked up using some simple method such as by subject name.
* These are:
* 1. Check issuer_name(subject) == subject_name(issuer)
* 2. If akid(subject) exists, check that it matches issuer
* 3. Check that issuer public key algorithm matches subject signature algorithm
* 4. Check that any key_usage(issuer) allows certificate signing
* Note that this does not include actually checking the signature.
* Returns 0 for OK, or positive for reason for mismatch
* where reason codes match those for X509_verify_cert().
*/
int X509_check_issued(X509 *issuer, X509 *subject)
{
int ret;
if ((ret = x509_likely_issued(issuer, subject)) != X509_V_OK)
return ret;
return x509_signing_allowed(issuer, subject);
}
/* do the checks 1., 2., and 3. as described above for X509_check_issued() */
int x509_likely_issued(X509 *issuer, X509 *subject)
{
int ret;
if (X509_NAME_cmp(X509_get_subject_name(issuer),
X509_get_issuer_name(subject)) != 0)
return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
/* set issuer->skid and subject->akid */
if (!x509v3_cache_extensions(issuer)
|| !x509v3_cache_extensions(subject))
return X509_V_ERR_UNSPECIFIED;
ret = X509_check_akid(issuer, subject->akid);
if (ret != X509_V_OK)
return ret;
/* check if the subject signature alg matches the issuer's PUBKEY alg */
return check_sig_alg_match(X509_get0_pubkey(issuer), subject);
}
/*-
* Check if certificate I<issuer> is allowed to issue certificate I<subject>
* according to the B<keyUsage> field of I<issuer> if present
* depending on any proxyCertInfo extension of I<subject>.
* Returns 0 for OK, or positive for reason for rejection
* where reason codes match those for X509_verify_cert().
*/
int x509_signing_allowed(const X509 *issuer, const X509 *subject)
{
if (subject->ex_flags & EXFLAG_PROXY) {
if (ku_reject(issuer, KU_DIGITAL_SIGNATURE))
return X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE;
} else if (ku_reject(issuer, KU_KEY_CERT_SIGN))
return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
return X509_V_OK;
}
int X509_check_akid(const X509 *issuer, const AUTHORITY_KEYID *akid)
{
if (akid == NULL)
return X509_V_OK;
/* Check key ids (if present) */
if (akid->keyid && issuer->skid &&
ASN1_OCTET_STRING_cmp(akid->keyid, issuer->skid))
return X509_V_ERR_AKID_SKID_MISMATCH;
/* Check serial number */
if (akid->serial &&
ASN1_INTEGER_cmp(X509_get0_serialNumber(issuer), akid->serial))
return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
/* Check issuer name */
if (akid->issuer) {
/*
* Ugh, for some peculiar reason AKID includes SEQUENCE OF
* GeneralName. So look for a DirName. There may be more than one but
* we only take any notice of the first.
*/
GENERAL_NAMES *gens;
GENERAL_NAME *gen;
X509_NAME *nm = NULL;
int i;
gens = akid->issuer;
for (i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
gen = sk_GENERAL_NAME_value(gens, i);
if (gen->type == GEN_DIRNAME) {
nm = gen->d.dirn;
break;
}
}
if (nm != NULL && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)) != 0)
return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
}
return X509_V_OK;
}
uint32_t X509_get_extension_flags(X509 *x)
{
/* Call for side-effect of computing hash and caching extensions */
X509_check_purpose(x, -1, -1);
return x->ex_flags;
}
uint32_t X509_get_key_usage(X509 *x)
{
/* Call for side-effect of computing hash and caching extensions */
if (X509_check_purpose(x, -1, -1) != 1)
return 0;
if (x->ex_flags & EXFLAG_KUSAGE)
return x->ex_kusage;
return UINT32_MAX;
}
uint32_t X509_get_extended_key_usage(X509 *x)
{
/* Call for side-effect of computing hash and caching extensions */
if (X509_check_purpose(x, -1, -1) != 1)
return 0;
if (x->ex_flags & EXFLAG_XKUSAGE)
return x->ex_xkusage;
return UINT32_MAX;
}
const ASN1_OCTET_STRING *X509_get0_subject_key_id(X509 *x)
{
/* Call for side-effect of computing hash and caching extensions */
if (X509_check_purpose(x, -1, -1) != 1)
return NULL;
return x->skid;
}
const ASN1_OCTET_STRING *X509_get0_authority_key_id(X509 *x)
{
/* Call for side-effect of computing hash and caching extensions */
if (X509_check_purpose(x, -1, -1) != 1)
return NULL;
return (x->akid != NULL ? x->akid->keyid : NULL);
}
const GENERAL_NAMES *X509_get0_authority_issuer(X509 *x)
{
/* Call for side-effect of computing hash and caching extensions */
if (X509_check_purpose(x, -1, -1) != 1)
return NULL;
return (x->akid != NULL ? x->akid->issuer : NULL);
}
const ASN1_INTEGER *X509_get0_authority_serial(X509 *x)
{
/* Call for side-effect of computing hash and caching extensions */
if (X509_check_purpose(x, -1, -1) != 1)
return NULL;
return (x->akid != NULL ? x->akid->serial : NULL);
}
long X509_get_pathlen(X509 *x)
{
/* Called for side effect of caching extensions */
if (X509_check_purpose(x, -1, -1) != 1
|| (x->ex_flags & EXFLAG_BCONS) == 0)
return -1;
return x->ex_pathlen;
}
long X509_get_proxy_pathlen(X509 *x)
{
/* Called for side effect of caching extensions */
if (X509_check_purpose(x, -1, -1) != 1
|| (x->ex_flags & EXFLAG_PROXY) == 0)
return -1;
return x->ex_pcpathlen;
}
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