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Streamline TLS session ticket key handling (added in r1200040):

Browse Source 
- drop the SSLTicketKeyDefault directive, and only support a single
  ticket key per server/vhost
- rename the SSLTicketKeyFile directive to SSLSessionTicketKeyFile,
  remove the keyname parameter
- move ticket key parameters from SSLSrvConfigRec to modssl_ctx_t
- configure the tlsext_ticket_key_cb only when in server mode
- add documentation for SSLSessionTicketKeyFile


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1213380 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Kaspar Brand
2011-12-12 19:21:35 +00:00
parent 91ce790cd3
commit 8d37f73ce7
7 changed files with 199 additions and 203 deletions
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2
docs/log-message-tags/next-number
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@@ -1 +1 @@
2286
2291

36
docs/manual/mod/mod_ssl.xml
View File

@@ -2265,4 +2265,40 @@ Of potential use when going through a proxy for retrieving OCSP queries.</p>
</usage>
</directivesynopsis>
<directivesynopsis>
<name>SSLSessionTicketKeyFile</name>
<description>Persistent encryption/decryption key for TLS session tickets</description>
<syntax>SSLSessionTicketKeyFile <em>file-path</em></syntax>
<contextlist><context>server config</context>
<context>virtual host</context></contextlist>
<compatibility>Available in httpd 2.4.0 and later, if using OpenSSL 0.9.8h or later</compatibility>
<usage>
<p>Optionally configures a secret key for encrypting and decrypting
TLS session tickets, as defined in
<a href="http://www.ietf.org/rfc/rfc5077.txt">RFC 5077</a>.
Primarily suitable for clustered environments where TLS sessions information
should be shared between multiple nodes. For single-instance httpd setups,
it is recommended to <em>not</em> configure a ticket key file, but to
rely on (random) keys generated by mod_ssl at startup, instead.</p>
<p>The ticket key file must contain 48 bytes of random data,
preferrably created from a high-entropy source. On a Unix-based system,
a ticket key file can be created as follows:</p>
<example>
dd if=/dev/random of=/path/to/file.tkey bs=1 count=48
</example>
<p>Ticket keys should be rotated (replaced) on a frequent basis,
as this is the only way to invalidate an existing session ticket -
OpenSSL currently doesn't allow to specify a limit for ticket lifetimes.</p>
<note type="warning">
<p>The ticket key file contains sensitive keying material and should
be protected with file permissions similar to those used for
<directive module="mod_ssl">SSLCertificateKeyFile</directive>.</p>
</note>
</usage>
</directivesynopsis>
</modulesynopsis>

13
modules/ssl/mod_ssl.c
View File

@@ -79,14 +79,6 @@ static const command_rec ssl_config_cmds[] = {
SSL_CMD_SRV(FIPS, FLAG,
"Enable FIPS-140 mode "
"(`on', `off')")
#ifdef HAVE_TLSEXT_TICKETS
SSL_CMD_SRV(TicketKeyFile, TAKE2,
"Key file to use for encrypting and decrypting the client ticket (RFC 5077) "
"(keyname '/path/to/file')")
SSL_CMD_SRV(TicketKeyDefault, TAKE1,
"Set the key name used by default for new sessions "
"(keyname)")
#endif
SSL_CMD_ALL(CipherSuite, TAKE1,
"Colon-delimited list of permitted SSL Ciphers "
"('XXX:...:XXX' - see manual)")
@@ -102,6 +94,11 @@ static const command_rec ssl_config_cmds[] = {
SSL_CMD_SRV(PKCS7CertificateFile, TAKE1,
"PKCS#7 file containing server certificate and chain"
" certificates ('/path/to/file' - PEM encoded)")
#ifdef HAVE_TLS_SESSION_TICKETS
SSL_CMD_SRV(SessionTicketKeyFile, TAKE1,
"TLS session ticket encryption/decryption key file (RFC 5077) "
"('/path/to/file' - file with 48 bytes of random data)")
#endif
SSL_CMD_ALL(CACertificatePath, TAKE1,
"SSL CA Certificate path "
"('/path/to/dir' - contains PEM encoded files)")

99
modules/ssl/ssl_engine_config.c
View File

@@ -109,6 +109,10 @@ static void modssl_ctx_init(modssl_ctx_t *mctx)
mctx->pks = NULL;
mctx->pkp = NULL;
#ifdef HAVE_TLS_SESSION_TICKETS
mctx->ticket_key = NULL;
#endif
mctx->protocol = SSL_PROTOCOL_ALL;
mctx->pphrase_dialog_type = SSL_PPTYPE_UNSET;
@@ -177,6 +181,10 @@ static void modssl_ctx_init_server(SSLSrvConfigRec *sc,
mctx->pks = apr_pcalloc(p, sizeof(*mctx->pks));
/* mctx->pks->... certs/keys are set during module init */
#ifdef HAVE_TLS_SESSION_TICKETS
mctx->ticket_key = apr_pcalloc(p, sizeof(*mctx->ticket_key));
#endif
}
static SSLSrvConfigRec *ssl_config_server_new(apr_pool_t *p)
@@ -200,12 +208,6 @@ static SSLSrvConfigRec *ssl_config_server_new(apr_pool_t *p)
sc->fips = UNSET;
#endif
#ifdef HAVE_TLSEXT_TICKETS
sc->default_ticket_name = NULL;
sc->default_ticket = NULL;
sc->tickets = apr_array_make(p, 4, sizeof(modssl_ticket_t*));
#endif
modssl_ctx_init_proxy(sc, p);
modssl_ctx_init_server(sc, p);
@@ -297,6 +299,10 @@ static void modssl_ctx_cfg_merge_server(modssl_ctx_t *base,
cfgMergeString(pks->ca_name_path);
cfgMergeString(pks->ca_name_file);
#ifdef HAVE_TLS_SESSION_TICKETS
cfgMergeString(ticket_key->file_path);
#endif
}
/*
@@ -310,11 +316,6 @@ void *ssl_config_server_merge(apr_pool_t *p, void *basev, void *addv)
cfgMerge(mc, NULL);
cfgMerge(enabled, SSL_ENABLED_UNSET);
#ifdef HAVE_TLSEXT_TICKETS
cfgMergeString(default_ticket_name);
apr_array_cat(mrg->tickets, base->tickets);
apr_array_cat(mrg->tickets, add->tickets);
#endif
cfgMergeBool(proxy_enabled);
cfgMergeInt(session_cache_timeout);
cfgMergeBool(cipher_server_pref);
@@ -595,64 +596,6 @@ const char *ssl_cmd_SSLEngine(cmd_parms *cmd, void *dcfg, const char *arg)
return "Argument must be On, Off, or Optional";
}
const char *ssl_cmd_SSLTicketKeyDefault(cmd_parms *cmd, void *dcfg, const char *name)
{
#ifdef HAVE_TLSEXT_TICKETS
SSLSrvConfigRec *sc = mySrvConfig(cmd->server);
sc->default_ticket_name = name;
return NULL;
#else
return "TLS Ticket keys are not supported.";
#endif
}
const char *ssl_cmd_SSLTicketKeyFile(cmd_parms *cmd, void *dcfg, const char *name, const char *path)
{
#ifdef HAVE_TLSEXT_TICKETS
apr_status_t rv;
apr_file_t *fp;
apr_size_t len;
char buf[TLSEXT_TICKET_KEYLEN];
modssl_ticket_t* ticket = NULL;
SSLSrvConfigRec *sc = mySrvConfig(cmd->server);
path = ap_server_root_relative(cmd->pool, path);
rv = apr_file_open(&fp, path, APR_READ|APR_BINARY,
APR_OS_DEFAULT, cmd->temp_pool);
if (rv != APR_SUCCESS) {
return apr_psprintf(cmd->pool,
"Failed to open %s: (%d) %pm",
path, rv, &rv);
}
rv = apr_file_read_full(fp, &buf[0], TLSEXT_TICKET_KEYLEN, &len);
if (rv != APR_SUCCESS) {
return apr_psprintf(cmd->pool,
"Failed to read at least 48 bytes from %s: (%d) %pm",
path, rv, &rv);
}
ticket = apr_palloc(cmd->pool, sizeof(modssl_ticket_t));
ticket->conf_name = name;
memcpy(ticket->key_name, buf, 16);
memcpy(ticket->hmac_secret, buf + 16, 16);
memcpy(ticket->aes_key, buf + 32, 16);
APR_ARRAY_PUSH(sc->tickets, modssl_ticket_t*) = ticket;
return NULL;
#else
return "TLS Ticket keys are not supported.";
#endif
}
const char *ssl_cmd_SSLFIPS(cmd_parms *cmd, void *dcfg, int flag)
{
#ifdef HAVE_FIPS
@@ -863,6 +806,24 @@ const char *ssl_cmd_SSLPKCS7CertificateFile(cmd_parms *cmd,
return NULL;
}
#ifdef HAVE_TLS_SESSION_TICKETS
const char *ssl_cmd_SSLSessionTicketKeyFile(cmd_parms *cmd,
void *dcfg,
const char *arg)
{
SSLSrvConfigRec *sc = mySrvConfig(cmd->server);
const char *err;
if ((err = ssl_cmd_check_file(cmd, &arg))) {
return err;
}
sc->server->ticket_key->file_path = arg;
return NULL;
}
#endif
#define NO_PER_DIR_SSL_CA \
"Your SSL library does not have support for per-directory CA"

74
modules/ssl/ssl_engine_init.c
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@@ -1134,45 +1134,65 @@ static void ssl_init_server_certs(server_rec *s,
#endif
ssl_die();
}
#ifdef HAVE_TLSEXT_TICKETS
if (mctx->sc->tickets->nelts > 0) {
if (mctx->sc->default_ticket_name != NULL) {
int i;
modssl_ticket_t* ticket = NULL;
mctx->sc->default_ticket = NULL;
for (i = 0; i < mctx->sc->tickets->nelts; i++) {
ticket = APR_ARRAY_IDX(mctx->sc->tickets, i, modssl_ticket_t*);
if (strcmp(ticket->conf_name, mctx->sc->default_ticket_name) == 0) {
mctx->sc->default_ticket = ticket;
}
}
if (mctx->sc->default_ticket == NULL) {
ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(01912)
"Misconfigured TLS Tickets. Couldn't find key named '%s'",
mctx->sc->default_ticket_name);
#ifdef HAVE_TLS_SESSION_TICKETS
static void ssl_init_ticket_key(server_rec *s,
apr_pool_t *p,
apr_pool_t *ptemp,
modssl_ctx_t *mctx)
{
apr_status_t rv;
apr_file_t *fp;
apr_size_t len;
char buf[TLSEXT_TICKET_KEY_LEN];
char *path;
modssl_ticket_key_t *ticket_key = mctx->ticket_key;
if (!ticket_key->file_path) {
return;
}
path = ap_server_root_relative(p, ticket_key->file_path);
rv = apr_file_open(&fp, path, APR_READ|APR_BINARY,
APR_OS_DEFAULT, ptemp);
if (rv != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(02286)
"Failed to open ticket key file %s: (%d) %pm",
path, rv, &rv);
ssl_die();
}
}
else {
mctx->sc->default_ticket = APR_ARRAY_IDX(mctx->sc->tickets, 0, modssl_ticket_t*);
rv = apr_file_read_full(fp, &buf[0], TLSEXT_TICKET_KEY_LEN, &len);
if (rv != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(02287)
"Failed to read %d bytes from %s: (%d) %pm",
TLSEXT_TICKET_KEY_LEN, path, rv, &rv);
ssl_die();
}
if (!SSL_CTX_set_tlsext_ticket_key_cb(mctx->ssl_ctx, ssl_callback_tlsext_tickets)) {
memcpy(ticket_key->key_name, buf, 16);
memcpy(ticket_key->hmac_secret, buf + 16, 16);
memcpy(ticket_key->aes_key, buf + 32, 16);
if (!SSL_CTX_set_tlsext_ticket_key_cb(mctx->ssl_ctx,
ssl_callback_SessionTicket)) {
ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(01913)
"Unable to initialize TLS session ticket extension "
"Unable to initialize TLS session ticket key callback "
"(incompatible OpenSSL version?)");
ssl_log_ssl_error(SSLLOG_MARK, APLOG_EMERG, s);
ssl_die();
}
ap_log_error(APLOG_MARK, APLOG_INFO, 0, s, APLOGNO(02288)
"TLS session ticket key for %s successfully loaded from %s",
(mySrvConfig(s))->vhost_id, path);
}
#endif
}
static void ssl_init_proxy_certs(server_rec *s,
apr_pool_t *p,
apr_pool_t *ptemp,
@@ -1322,6 +1342,10 @@ static void ssl_init_server_ctx(server_rec *s,
ssl_init_ctx(s, p, ptemp, sc->server);
ssl_init_server_certs(s, p, ptemp, sc->server);
#ifdef HAVE_TLS_SESSION_TICKETS
ssl_init_ticket_key(s, p, ptemp, sc->server);
#endif
}
/*

91
modules/ssl/ssl_engine_kernel.c
View File

@@ -2088,91 +2088,72 @@ static int ssl_find_vhost(void *servername, conn_rec *c, server_rec *s)
}
#endif
#ifdef HAVE_TLSEXT_TICKETS
#ifndef tlsext_tick_md
#ifdef OPENSSL_NO_SHA256
#define tlsext_tick_md EVP_sha1
#else
#define tlsext_tick_md EVP_sha256
#endif
#endif
int ssl_callback_tlsext_tickets(SSL *ssl,
#ifdef HAVE_TLS_SESSION_TICKETS
/*
* This callback function is executed when OpenSSL needs a key for encrypting/
* decrypting a TLS session ticket (RFC 5077) and a ticket key file has been
* configured through SSLSessionTicketKeyFile.
*/
int ssl_callback_SessionTicket(SSL *ssl,
unsigned char *keyname,
unsigned char *iv,
EVP_CIPHER_CTX *cipher_ctx,
HMAC_CTX *hctx,
int mode)
{
conn_rec *conn = (conn_rec *)SSL_get_app_data(ssl);
server_rec *s = mySrvFromConn(conn);
conn_rec *c = (conn_rec *)SSL_get_app_data(ssl);
server_rec *s = mySrvFromConn(c);
SSLSrvConfigRec *sc = mySrvConfig(s);
SSLConnRec *sslconn = myConnConfig(c);
modssl_ctx_t *mctx = myCtxConfig(sslconn, sc);
modssl_ticket_key_t *ticket_key = mctx->ticket_key;
if (mode == 1) {
modssl_ticket_t* ticket = sc->default_ticket;
/* Setting up the stuff for encrypting:
* - keyname contains at least 16 bytes we can write to.
* - iv contains at least EVP_MAX_IV_LENGTH (16) bytes we can write to.
* - hctx is already allocated, we just need to set the
* secret key via HMAC_Init_ex.
* - cipher_ctx is also allocated, and we need to configure
* the cipher and private key.
/*
* OpenSSL is asking for a key for encrypting a ticket,
* see s3_srvr.c:ssl3_send_newsession_ticket()
*/
if (ticket == NULL) {
/* this should not happen, we always set the default
* ticket.
*/
if (ticket_key == NULL) {
/* should never happen, but better safe than sorry */
return -1;
}
memcpy(keyname, ticket->key_name, 16);
memcpy(keyname, ticket_key->key_name, 16);
RAND_pseudo_bytes(iv, EVP_MAX_IV_LENGTH);
EVP_EncryptInit_ex(cipher_ctx, EVP_aes_128_cbc(), NULL,
ticket->aes_key, iv);
ticket_key->aes_key, iv);
HMAC_Init_ex(hctx, ticket_key->hmac_secret, 16, tlsext_tick_md(), NULL);
HMAC_Init_ex(hctx, ticket->hmac_secret, 16, tlsext_tick_md(), NULL);
ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, c, APLOGNO(02289)
"TLS session ticket key for %s successfully set, "
"creating new session ticket", sc->vhost_id);
return 0;
}
else if (mode == 0) {
/* Setup contextes for decryption, based on the keyname input */
int i;
modssl_ticket_t* ticket = NULL;
/*
* OpenSSL is asking for the decryption key,
* see t1_lib.c:tls_decrypt_ticket()
*/
for (i = 0; i < sc->tickets->nelts; i++) {
modssl_ticket_t* itticket = APR_ARRAY_IDX(sc->tickets, i, modssl_ticket_t*);
if (memcmp(keyname, itticket->key_name, 16) == 0) {
ticket = itticket;
break;
}
}
if (ticket == NULL) {
/* Ticket key not found, but no error */
/* check key name */
if (ticket_key == NULL || memcmp(keyname, ticket_key->key_name, 16)) {
return 0;
}
EVP_DecryptInit_ex(cipher_ctx, EVP_aes_128_cbc(), NULL, ticket->aes_key, iv);
EVP_DecryptInit_ex(cipher_ctx, EVP_aes_128_cbc(), NULL,
ticket_key->aes_key, iv);
HMAC_Init_ex(hctx, ticket_key->hmac_secret, 16, tlsext_tick_md(), NULL);
HMAC_Init_ex(hctx, ticket->hmac_secret, 16, tlsext_tick_md(), NULL);
ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, c, APLOGNO(02290)
"TLS session ticket key for %s successfully set, "
"decrypting existing session ticket", sc->vhost_id);
if (ticket != sc->default_ticket) {
/* Ticket key found, we did our stuff, but didn't use the default,
* re-issue a ticket with the default ticket */
return 2;
}
else {
return 1;
}
}
/* TODO: log invalid use */
/* OpenSSL is not expected to call us with modes other than 1 or 0 */
return -1;
}
#endif

51
modules/ssl/ssl_private.h
View File

@@ -158,8 +158,16 @@
#endif
#ifndef OPENSSL_NO_TLSEXT
#ifdef SSL_CTX_set_tlsext_ticket_key_cb
#define HAVE_TLSEXT_TICKETS
#ifdef SSL_CTRL_SET_TLSEXT_TICKET_KEY_CB
#define HAVE_TLS_SESSION_TICKETS
#define TLSEXT_TICKET_KEY_LEN 48
#ifndef tlsext_tick_md
#ifdef OPENSSL_NO_SHA256
#define tlsext_tick_md EVP_sha1
#else
#define tlsext_tick_md EVP_sha256
#endif
#endif
#endif
#endif
@@ -559,19 +567,13 @@ typedef struct {
ssl_verify_t verify_mode;
} modssl_auth_ctx_t;
#ifdef HAVE_TLSEXT_TICKETS
/* 48 bytes: 16 for keyname, 16 for HMAC secret, 16 for AES private key */
#define TLSEXT_TICKET_KEYLEN (48)
#ifdef HAVE_TLS_SESSION_TICKETS
typedef struct {
/* Human readable name, used in the configuration */
const char *conf_name;
char key_name[16];
const char *file_path;
unsigned char key_name[16];
unsigned char hmac_secret[16];
unsigned char aes_key[16];
} modssl_ticket_t;
} modssl_ticket_key_t;
#endif
typedef struct SSLSrvConfigRec SSLSrvConfigRec;
@@ -584,6 +586,10 @@ typedef struct {
modssl_pk_server_t *pks;
modssl_pk_proxy_t *pkp;
#ifdef HAVE_TLS_SESSION_TICKETS
modssl_ticket_key_t *ticket_key;
#endif
ssl_proto_t protocol;
/** config for handling encrypted keys */
@@ -642,11 +648,6 @@ struct SSLSrvConfigRec {
#ifdef HAVE_FIPS
BOOL fips;
#endif
#ifdef HAVE_TLSEXT_TICKETS
const char *default_ticket_name;
modssl_ticket_t* default_ticket;
apr_array_header_t* tickets;
#endif
};
/**
@@ -727,6 +728,9 @@ const char *ssl_cmd_SSLProxyCARevocationCheck(cmd_parms *, void *, const char *
const char *ssl_cmd_SSLProxyMachineCertificatePath(cmd_parms *, void *, const char *);
const char *ssl_cmd_SSLProxyMachineCertificateFile(cmd_parms *, void *, const char *);
const char *ssl_cmd_SSLProxyMachineCertificateChainFile(cmd_parms *, void *, const char *);
#ifdef HAVE_TLS_SESSION_TICKETS
const char *ssl_cmd_SSLSessionTicketKeyFile(cmd_parms *cmd, void *dcfg, const char *arg);
#endif
const char *ssl_cmd_SSLProxyCheckPeerExpire(cmd_parms *cmd, void *dcfg, int flag);
const char *ssl_cmd_SSLProxyCheckPeerCN(cmd_parms *cmd, void *dcfg, int flag);
@@ -738,8 +742,6 @@ const char *ssl_cmd_SSLOCSPResponderTimeout(cmd_parms *cmd, void *dcfg, const ch
const char *ssl_cmd_SSLOCSPEnable(cmd_parms *cmd, void *dcfg, int flag);
const char *ssl_cmd_SSLFIPS(cmd_parms *cmd, void *dcfg, int flag);
const char *ssl_cmd_SSLTicketKeyDefault(cmd_parms *cmd, void *dcfg, const char *name);
const char *ssl_cmd_SSLTicketKeyFile(cmd_parms *cmd, void *dcfg, const char *name, const char *path);
/** module initialization */
int ssl_init_Module(apr_pool_t *, apr_pool_t *, apr_pool_t *, server_rec *);
@@ -780,14 +782,9 @@ void ssl_callback_Info(const SSL *, int, int);
#ifndef OPENSSL_NO_TLSEXT
int ssl_callback_ServerNameIndication(SSL *, int *, modssl_ctx_t *);
#endif
#ifdef HAVE_TLSEXT_TICKETS
int ssl_callback_tlsext_tickets(SSL *ssl,
unsigned char *keyname,
unsigned char *iv,
EVP_CIPHER_CTX *cipher_ctx,
HMAC_CTX *hctx,
int mode);
#ifdef HAVE_TLS_SESSION_TICKETS
int ssl_callback_SessionTicket(SSL *, unsigned char *, unsigned char *,
EVP_CIPHER_CTX *, HMAC_CTX *, int);
#endif
/** Session Cache Support */