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[mod_openssl] OCSP stapling (fixes #2469)

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Define ssl.stapling-file in lighttpd.conf in same scope as ssl.pemfile

x-ref:
  "OCSP Stapling"
  https://redmine.lighttpd.net/issues/2469
personal/stbuehler/ci-build
Glenn Strauss 3 years ago
parent 60ddaf26c4
commit b2b6257c7a
1 changed files with 427 additions and 6 deletions
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433
src/mod_openssl.c
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@ -6,8 +6,6 @@
* License: BSD 3-clause (same as lighttpd)
*/
/*
* future possible enhancements: OCSP stapling
*
* Note: If session tickets are -not- disabled with
* ssl.openssl.ssl-conf-cmd = ("Options" => "-SessionTicket")
* mod_openssl rotates server ticket encryption key (STEK) every 8 hours
@ -34,6 +32,7 @@
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
@ -71,6 +70,9 @@
#ifndef OPENSSL_NO_DH
#include <openssl/dh.h>
#endif
#ifndef OPENSSL_NO_OCSP
#include <openssl/ocsp.h>
#endif
#if ! defined OPENSSL_NO_TLSEXT && ! defined SSL_CTRL_SET_TLSEXT_HOSTNAME
#define OPENSSL_NO_TLSEXT
@ -113,8 +115,12 @@ typedef struct {
EVP_PKEY *ssl_pemfile_pkey;
X509 *ssl_pemfile_x509;
STACK_OF(X509) *ssl_pemfile_chain;
buffer *ssl_stapling;
const buffer *ssl_pemfile;
const buffer *ssl_privkey;
const buffer *ssl_stapling_file;
time_t ssl_stapling_loadts;
time_t ssl_stapling_nextts;
} plugin_cert;
typedef struct {
@ -437,6 +443,49 @@ mod_openssl_session_ticket_key_check (const plugin_data *p, const time_t cur_ts)
#endif /* TLSEXT_TYPE_session_ticket */
#ifndef OPENSSL_NO_OCSP
#ifndef BORINGSSL_API_VERSION /* BoringSSL suggests using different API */
static int
ssl_tlsext_status_cb(SSL *ssl, void *arg)
{
#ifdef SSL_get_tlsext_status_type
if (TLSEXT_STATUSTYPE_ocsp != SSL_get_tlsext_status_type(ssl))
return SSL_TLSEXT_ERR_NOACK; /* ignore if not client OCSP request */
#endif
handler_ctx *hctx = (handler_ctx *) SSL_get_app_data(ssl);
buffer *ssl_stapling = hctx->conf.pc->ssl_stapling;
if (NULL == ssl_stapling) return SSL_TLSEXT_ERR_NOACK;
UNUSED(arg);
int len = (int)buffer_string_length(ssl_stapling);
#ifdef WOLFSSL_VERSION /* WolfSSL does not require copy */
uint8_t *ocsp_resp = (uint8_t *)ssl_stapling->ptr;
#else
/* OpenSSL and LibreSSL require copy (BoringSSL, too, if using compat API)*/
uint8_t *ocsp_resp = OPENSSL_malloc(len);
if (NULL == ocsp_resp)
return SSL_TLSEXT_ERR_NOACK; /* ignore OCSP request if error occurs */
memcpy(ocsp_resp, ssl_stapling->ptr, len);
#endif
if (!SSL_set_tlsext_status_ocsp_resp(ssl, ocsp_resp, len)) {
log_error(hctx->r->conf.errh, __FILE__, __LINE__,
"SSL: failed to set OCSP response for TLS server name %s: %s",
hctx->r->uri.authority.ptr, ERR_error_string(ERR_get_error(), NULL));
#ifndef WOLFSSL_VERSION /* WolfSSL does not require copy */
OPENSSL_free(ocsp_resp);
#endif
return SSL_TLSEXT_ERR_NOACK; /* ignore OCSP request if error occurs */
/*return SSL_TLSEXT_ERR_ALERT_FATAL;*/
}
return SSL_TLSEXT_ERR_OK;
}
#endif
#endif
INIT_FUNC(mod_openssl_init)
{
plugin_data_singleton = (plugin_data *)calloc(1, sizeof(plugin_data));
@ -551,6 +600,7 @@ mod_openssl_free_config (server *srv, plugin_data * const p)
EVP_PKEY_free(pc->ssl_pemfile_pkey);
X509_free(pc->ssl_pemfile_x509);
sk_X509_pop_free(pc->ssl_pemfile_chain, X509_free);
buffer_free(pc->ssl_stapling);
}
break;
case 2: /* ssl.ca-file */
@ -889,7 +939,9 @@ mod_openssl_merge_config_cpv (plugin_config * const pconf, const config_plugin_v
case 12:/* ssl.acme-tls-1 */
pconf->ssl_acme_tls_1 = cpv->v.b;
break;
case 13:/* debug.log-ssl-noise */
case 13:/* ssl.stapling-file */
break;
case 14:/* debug.log-ssl-noise */
pconf->ssl_log_noise = (0 != cpv->v.u);
break;
default:/* should not happen */
@ -1120,6 +1172,20 @@ mod_openssl_cert_cb (SSL *ssl, void *arg)
return 0;
}
#ifndef OPENSSL_NO_OCSP
#ifdef BORINGSSL_API_VERSION
/* BoringSSL suggests API different than SSL_CTX_set_tlsext_status_cb() */
buffer *ocsp_resp = pc->ssl_stapling;
if (NULL != ocsp_resp
&& !SSL_set_ocsp_response(ssl, (uint8_t *)CONST_BUF_LEN(ocsp_resp))) {
log_error(hctx->r->conf.errh, __FILE__, __LINE__,
"SSL: failed to set OCSP response for TLS server name %s: %s",
hctx->r->uri.authority.ptr, ERR_error_string(ERR_get_error(), NULL));
return 0;
}
#endif
#endif
if (hctx->conf.ssl_verifyclient) {
if (NULL == hctx->conf.ssl_ca_file) {
log_error(hctx->r->conf.errh, __FILE__, __LINE__,
@ -1303,8 +1369,327 @@ mod_openssl_evp_pkey_load_pem_file (const char *file, log_error_st *errh)
}
#ifndef OPENSSL_NO_OCSP
static buffer *
mod_openssl_load_stapling_file (const char *file, log_error_st *errh, buffer *b)
{
/* load stapling .der into buffer *b only if successful
*
* Note: for some TLS libs, the OCSP stapling response is not copied when
* assigned to a session (and is reasonable since not changed frequently)
* - BoringSSL SSL_set_ocsp_response()
* - WolfSSL SSL_set_tlsext_status_ocsp_resp() (differs from OpenSSL API)
* Therefore, there is a potential race condition if the OCSP response is
* assigned to the session during the handshake and the Server Hello is
* partially sent, AND (unlikely, if possible at all), the TLS library is
* in the middle of reading this OSCP response buffer. If the OCSP response
* is replaced due to an updated ssl.stapling-file (checked periodically),
* AND the buffer is resized, this would be a problem. Resizing the buffer
* is unlikely since updated OSCP response for same certificate are
* typically the same size with the signature and dates refreshed.
*/
#ifdef BORINGSSL_API_VERSION
/* load raw .der file */
/* (similar to mod_gnutls.c:mod_gnutls_load_file(), but some differences) */
int fd = -1;
uint32_t sz = 0;
char *buf = NULL;
do {
fd = fdevent_open_cloexec(file,1,O_RDONLY,0); /*(1: follows symlinks)*/
if (fd < 0) break;
struct stat st;
if (0 != fstat(fd, &st)) break;
if (st.st_size == 0) break;
if (st.st_size >= UINT32_MAX) { /*(file too large for buffer uint32_t)*/
errno = EOVERFLOW;
break;
}
sz = (uint32_t)st.st_size;
buf = malloc(sz+1); /*(+1 trailing '\0')*/
if (NULL == buf) break;
ssize_t rd = 0;
unsigned int off = 0;
do {
rd = read(fd, buf+off, sz-off);
} while (rd > 0 ? (off += (unsigned int)rd) != sz : errno == EINTR);
if (off != sz) { /*(file truncated?)*/
if (rd >= 0) errno = EIO;
break;
}
if (NULL == b) b = buffer_init();
buffer_copy_string_len(b, buf, sz);
memset(buf, 0, sz);
free(buf);
close(fd);
return b;
} while (0);
int errnum = errno;
log_perror(errh, __FILE__, __LINE__, "%s() %s", __func__, file);
if (fd >= 0) close(fd);
if (buf) {
memset(buf, 0, sz);
free(buf);
}
errno = errnum;
return NULL;;
#else
BIO *in = BIO_new_rdonly_file(file);
if (NULL == in) {
log_error(errh, __FILE__, __LINE__,
"SSL: BIO_new/BIO_read_filename('%s') failed", file);
return NULL;
}
OCSP_RESPONSE *x = d2i_OCSP_RESPONSE_bio(in, NULL);
BIO_free(in);
if (NULL == x) {
log_error(errh, __FILE__, __LINE__,
"SSL: OCSP stapling file read error: %s %s",
ERR_error_string(ERR_get_error(), NULL), file);
return NULL;
}
unsigned char *rspder = NULL;
int rspderlen = i2d_OCSP_RESPONSE(x, &rspder);
if (rspderlen > 0) {
if (NULL == b) b = buffer_init();
buffer_copy_string_len(b, (char *)rspder, (uint32_t)rspderlen);
}
OPENSSL_free(rspder);
OCSP_RESPONSE_free(x);
return rspderlen ? b : NULL;
#endif
}
static time_t
mod_openssl_asn1_time_to_posix (ASN1_TIME *asn1time)
{
#ifdef LIBRESSL_VERSION_NUMBER
/* LibreSSL was forked from OpenSSL 1.0.1; does not have ASN1_TIME_diff */
/*(Note: all certificate times are expected to use UTC)*/
/*(Note: does not strictly validate string contains appropriate digits)*/
/*(Note: incorrectly assumes GMT if 'Z' or offset not provided)*/
/*(Note: incorrectly ignores if local timezone might be in DST)*/
if (NULL == asn1time || NULL == asn1time->data) return (time_t)-1;
const char *s = (const char *)asn1time->data;
size_t len = strlen(s);
struct tm x;
x.tm_isdst = 0;
x.tm_yday = 0;
x.tm_wday = 0;
switch (asn1time->type) {
case V_ASN1_UTCTIME: /* 2-digit year */
if (len < 8) return (time_t)-1;
len -= 8;
x.tm_year = (s[0]-'0')*10 + (s[1]-'0');
x.tm_year += (x.tm_year < 50 ? 2000 : 1900);
s += 2;
break;
case V_ASN1_GENERALIZEDTIME: /* 4-digit year */
if (len < 10) return (time_t)-1;
len -= 10;
x.tm_year = (s[0]-'0')*1000+(s[1]-'0')*100+(s[2]-'0')*10+(s[3]-'0');
s += 4;
break;
default:
return (time_t)-1;
}
x.tm_mon = (s[0]-'0')*10 + (s[1]-'0');
x.tm_mday = (s[2]-'0')*10 + (s[3]-'0');
x.tm_hour = (s[4]-'0')*10 + (s[5]-'0');
x.tm_min = 0;
x.tm_sec = 0;
s += 6;
if (len >= 2 && s[0] != '+' && s[0] != '-' && s[0] != 'Z') {
len -= 2;
x.tm_min = (s[0]-'0')*10 + (s[1]-'0');
s += 2;
if (len >= 2 && s[0] != '+' && s[0] != '-' && s[0] != 'Z') {
len -= 2;
x.tm_sec = (s[0]-'0')*10 + (s[1]-'0');
s += 2;
if (len && s[0] == '.') {
/*(ignore .fff fractional seconds;
* should be up to 3 digits but we ignore more)*/
do { ++s; --len; } while (*s >= '0' && *s <= '9');
}
}
}
int offset = 0;
if ((*s == '-' || *s == '+') && len != 5) {
offset = ((s[1]-'0')*10 + (s[2]-'0')) * 3600
+ ((s[3]-'0')*10 + (s[4]-'0')) * 60;
if (*s == '-') offset = -offset;
}
else if (s[0] != '\0' && (s[0] != 'Z' || s[1] != '\0'))
return (time_t)-1;
if (x.tm_year == 9999 && x.tm_mon == 12 && x.tm_mday == 31
&& x.tm_hour == 23 && x.tm_min == 59 && x.tm_sec == 59 && s[0] == 'Z')
return (time_t)-1; // 99991231235959Z RFC 5280
#if 0
#if defined(_WIN32) && !defined(__CYGWIN__)
#define timegm(x) _mkgmtime(x)
#endif
/* timegm() might not be available, and mktime() is sensitive to TZ */
x.tm_year-= 1900;
x.tm_mon -= 1;
time_t t = timegm(&d);
return (t != (time_t)-1) ? t + offset : t;
#else
int y = x.tm_year;
int m = x.tm_mon;
int d = x.tm_mday;
/* days_from_civil() http://howardhinnant.github.io/date_algorithms.html */
y -= m <= 2;
int era = y / 400;
int yoe = y - era * 400; // [0, 399]
int doy = (153 * (m + (m > 2 ? -3 : 9)) + 2) / 5 + d - 1; // [0, 365]
int doe = yoe * 365 + yoe / 4 - yoe / 100 + doy; // [0, 146096]
int days_since_1970 = era * 146097 + doe - 719468;
return 60*(60*(24L*days_since_1970+x.tm_hour)+x.tm_min)+x.tm_sec+offset;
#endif
#else
/* Note: this does not check for integer overflow of time_t! */
int day, sec;
return ASN1_TIME_diff(&day, &sec, NULL, asn1time)
? log_epoch_secs + day*86400 + sec
: (time_t)-1;
#endif
}
static time_t
mod_openssl_ocsp_next_update (plugin_cert *pc)
{
#ifdef BORINGSSL_API_VERSION
UNUSED(pc);
return (time_t)-1; /*(not implemented)*/
#else
buffer *der = pc->ssl_stapling;
const unsigned char *p = (unsigned char *)der->ptr; /*(p gets modified)*/
OCSP_RESPONSE *ocsp = d2i_OCSP_RESPONSE(NULL,&p,buffer_string_length(der));
if (NULL == ocsp) return (time_t)-1;
OCSP_BASICRESP *bs = OCSP_response_get1_basic(ocsp);
if (NULL == bs) {
OCSP_RESPONSE_free(ocsp);
return (time_t)-1;
}
/* XXX: should save and evaluate cert status returned by these calls */
ASN1_TIME *nextupd = NULL;
#ifdef WOLFSSL_VERSION /* WolfSSL limitation */
/* WolfSSL does not provide OCSP_resp_get0() OCSP_single_get0_status() */
OCSP_CERTID *id = (NULL != pc->ssl_pemfile_chain)
? OCSP_cert_to_id(NULL, pc->ssl_pemfile_x509,
sk_X509_value(pc->ssl_pemfile_chain, 0))
: NULL;
if (id == NULL) {
OCSP_BASICRESP_free(bs);
OCSP_RESPONSE_free(ocsp);
return (time_t)-1;
}
OCSP_resp_find_status(bs, id, NULL, NULL, NULL, NULL, &nextupd);
OCSP_CERTID_free(id);
#else
OCSP_single_get0_status(OCSP_resp_get0(bs, 0), NULL, NULL, NULL, &nextupd);
#endif
time_t t = nextupd ? mod_openssl_asn1_time_to_posix(nextupd) : (time_t)-1;
/* Note: trust external process which creates ssl.stapling-file to verify
* (as well as to validate certificate status)
* future: verify OCSP response here to double-check */
OCSP_BASICRESP_free(bs);
OCSP_RESPONSE_free(ocsp);
return t;
#endif
}
static int
mod_openssl_reload_stapling_file (server *srv, plugin_cert *pc, const time_t cur_ts)
{
buffer *b = mod_openssl_load_stapling_file(pc->ssl_stapling_file->ptr,
srv->errh, pc->ssl_stapling);
if (!b) return 0;
pc->ssl_stapling = b; /*(unchanged unless orig was NULL)*/
pc->ssl_stapling_loadts = cur_ts;
pc->ssl_stapling_nextts = mod_openssl_ocsp_next_update(pc);
if (pc->ssl_stapling_nextts == (time_t)-1) {
/* "Next Update" might not be provided by OCSP responder
* Use 3600 sec (1 hour) in that case. */
/* retry in 1 hour if unable to determine Next Update */
pc->ssl_stapling_nextts = cur_ts + 3600;
pc->ssl_stapling_loadts = 0;
}
return 1;
}
static int
mod_openssl_refresh_stapling_file (server *srv, plugin_cert *pc, const time_t cur_ts)
{
if (pc->ssl_stapling && pc->ssl_stapling_nextts - 256 > cur_ts)
return 1; /* skip check for refresh unless close to expire */
struct stat st;
if (0 != stat(pc->ssl_stapling_file->ptr, &st)
|| st.st_mtime <= pc->ssl_stapling_loadts) {
if (pc->ssl_stapling_nextts < cur_ts) {
/* discard expired OCSP stapling response */
buffer_free(pc->ssl_stapling);
pc->ssl_stapling = NULL;
}
return 1;
}
return mod_openssl_reload_stapling_file(srv, pc, cur_ts);
}
static void
mod_openssl_refresh_stapling_files (server *srv, const plugin_data *p, const time_t cur_ts)
{
/* future: might construct array of (plugin_cert *) at startup
* to avoid the need to search for them here */
for (int i = 0, used = p->nconfig; i < used; ++i) {
const config_plugin_value_t *cpv = p->cvlist + p->cvlist[i].v.u2[0];
for (; cpv->k_id != -1; ++cpv) {
if (cpv->k_id != 0) continue; /* k_id == 0 for ssl.pemfile */
if (cpv->vtype != T_CONFIG_LOCAL) continue;
plugin_cert *pc = cpv->v.v;
if (!buffer_string_is_empty(pc->ssl_stapling_file))
mod_openssl_refresh_stapling_file(srv, pc, cur_ts);
}
}
}
#endif
static plugin_cert *
network_openssl_load_pemfile (server *srv, const buffer *pemfile, const buffer *privkey)
network_openssl_load_pemfile (server *srv, const buffer *pemfile, const buffer *privkey, const buffer *ssl_stapling_file)
{
if (!mod_openssl_init_once_openssl(srv)) return NULL;
@ -1340,6 +1725,23 @@ network_openssl_load_pemfile (server *srv, const buffer *pemfile, const buffer *
pc->ssl_pemfile_chain= ssl_pemfile_chain;
pc->ssl_pemfile = pemfile;
pc->ssl_privkey = privkey;
pc->ssl_stapling = NULL;
pc->ssl_stapling_file= ssl_stapling_file;
pc->ssl_stapling_loadts = 0;
pc->ssl_stapling_nextts = 0;
if (!buffer_string_is_empty(pc->ssl_stapling_file)) {
#ifndef OPENSSL_NO_OCSP
if (!mod_openssl_reload_stapling_file(srv, pc, log_epoch_secs)) {
/* continue without OCSP response if there is an error */
}
#else
log_error(srv->errh, __FILE__, __LINE__, "SSL:"
"OCSP stapling not supported; ignoring %s",
pc->ssl_stapling_file->ptr);
#endif
}
return pc;
}
@ -1858,6 +2260,12 @@ network_init_ssl (server *srv, plugin_config_socket *s, plugin_data *p)
SSL_CTX_set_tlsext_ticket_key_cb(s->ssl_ctx, ssl_tlsext_ticket_key_cb);
#endif
#ifndef OPENSSL_NO_OCSP
#ifndef BORINGSSL_API_VERSION /* BoringSSL suggests using different API */
SSL_CTX_set_tlsext_status_cb(s->ssl_ctx, ssl_tlsext_status_cb);
#endif
#endif
#if OPENSSL_VERSION_NUMBER >= 0x10002000 \
&& !defined(LIBRESSL_VERSION_NUMBER)
@ -2259,6 +2667,9 @@ SETDEFAULTS_FUNC(mod_openssl_set_defaults)
,{ CONST_STR_LEN("ssl.acme-tls-1"),
T_CONFIG_STRING,
T_CONFIG_SCOPE_CONNECTION }
,{ CONST_STR_LEN("ssl.stapling-file"),
T_CONFIG_STRING,
T_CONFIG_SCOPE_CONNECTION }
,{ CONST_STR_LEN("debug.log-ssl-noise"),
T_CONFIG_BOOL,
T_CONFIG_SCOPE_CONNECTION }
@ -2281,6 +2692,7 @@ SETDEFAULTS_FUNC(mod_openssl_set_defaults)
config_plugin_value_t *cpv = p->cvlist + p->cvlist[i].v.u2[0];
config_plugin_value_t *pemfile = NULL;
config_plugin_value_t *privkey = NULL;
const buffer *ssl_stapling_file = NULL;
const buffer *ssl_ca_file = NULL;
const buffer *ssl_ca_dn_file = NULL;
const buffer *ssl_ca_crl_file = NULL;
@ -2345,7 +2757,11 @@ SETDEFAULTS_FUNC(mod_openssl_set_defaults)
case 10:/* ssl.verifyclient.username */
case 11:/* ssl.verifyclient.exportcert */
case 12:/* ssl.acme-tls-1 */
case 13:/* debug.log-ssl-noise */
break;
case 13:/* ssl.stapling-file */
ssl_stapling_file = cpv->v.b;
break;
case 14:/* debug.log-ssl-noise */
break;
default:/* should not happen */
break;
@ -2408,7 +2824,8 @@ SETDEFAULTS_FUNC(mod_openssl_set_defaults)
#endif
if (NULL == privkey) privkey = pemfile;
pemfile->v.v =
network_openssl_load_pemfile(srv, pemfile->v.b, privkey->v.b);
network_openssl_load_pemfile(srv, pemfile->v.b, privkey->v.b,
ssl_stapling_file);
if (pemfile->v.v)
pemfile->vtype = T_CONFIG_LOCAL;
else
@ -3174,6 +3591,10 @@ TRIGGER_FUNC(mod_openssl_handle_trigger) {
mod_openssl_session_ticket_key_check(p, cur_ts);
#endif
#ifndef OPENSSL_NO_OCSP
mod_openssl_refresh_stapling_files(srv, p, cur_ts);
#endif
return HANDLER_GO_ON;
}

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