EXPORTED int backend_starttls( struct backend *s,
struct tls_cmd_t *tls_cmd,
const char *c_cert_file,
const char *c_key_file)
{
#ifndef HAVE_SSL
return -1;
#else
char *auth_id = NULL;
int *layerp = NULL;
int r = 0;
if (tls_cmd) {
char buf[2048];
/* send starttls command */
prot_printf(s->out, "%s\r\n", tls_cmd->cmd);
prot_flush(s->out);
/* check response */
if (!prot_fgets(buf, sizeof(buf), s->in) ||
strncmp(buf, tls_cmd->ok, strlen(tls_cmd->ok)))
return -1;
}
r = tls_init_clientengine(5, c_cert_file, c_key_file);
if (r == -1) return -1;
/* SASL and openssl have different ideas about whether ssf is signed */
layerp = (int *) &s->ext_ssf;
r = tls_start_clienttls(s->in->fd, s->out->fd, layerp, &auth_id,
&s->tlsconn, &s->tlssess);
if (r == -1) return -1;
if (s->saslconn) {
r = sasl_setprop(s->saslconn, SASL_SSF_EXTERNAL, &s->ext_ssf);
if (r == SASL_OK)
r = sasl_setprop(s->saslconn, SASL_AUTH_EXTERNAL, auth_id);
if (auth_id) free(auth_id);
if (r != SASL_OK) return -1;
}
prot_settls(s->in, s->tlsconn);
prot_settls(s->out, s->tlsconn);
ask_capability(s, /*dobanner*/1, tls_cmd->auto_capa);
return 0;
#endif /* HAVE_SSL */
}
static int do_starttls(struct backend *s)
{
#ifndef HAVE_SSL
return -1;
#else
const struct tls_cmd_t *tls_cmd = &s->prot->tls_cmd;
char buf[2048];
int r;
int *layerp;
char *auth_id;
sasl_ssf_t ssf;
/* send starttls command */
prot_printf(s->out, "%s\r\n", tls_cmd->cmd);
prot_flush(s->out);
/* check response */
if (!prot_fgets(buf, sizeof(buf), s->in) ||
strncmp(buf, tls_cmd->ok, strlen(tls_cmd->ok)))
return -1;
r = tls_init_clientengine(5, "", "");
if (r == -1) return -1;
/* SASL and openssl have different ideas about whether ssf is signed */
layerp = (int *) &ssf;
r = tls_start_clienttls(s->in->fd, s->out->fd, layerp, &auth_id,
&s->tlsconn, &s->tlssess);
if (r == -1) return -1;
r = sasl_setprop(s->saslconn, SASL_SSF_EXTERNAL, &ssf);
if (r == SASL_OK)
r = sasl_setprop(s->saslconn, SASL_AUTH_EXTERNAL, auth_id);
if (auth_id) free(auth_id);
if (r != SASL_OK) return -1;
prot_settls(s->in, s->tlsconn);
prot_settls(s->out, s->tlsconn);
ask_capability(s, /*dobanner*/1, s->prot->tls_cmd.auto_capa);
return 0;
#endif /* HAVE_SSL */
}
struct backend *backend_connect(struct backend *ret_backend, const char *server,
struct protocol_t *prot, const char *userid,
sasl_callback_t *cb, const char **auth_status)
{
/* need to (re)establish connection to server or create one */
int sock = -1;
int r;
int err = -1;
int ask = 1; /* should we explicitly ask for capabilities? */
struct addrinfo hints, *res0 = NULL, *res;
struct sockaddr_un sunsock;
char buf[2048];
struct sigaction action;
struct backend *ret;
char rsessionid[MAX_SESSIONID_SIZE];
if (!ret_backend) {
ret = xzmalloc(sizeof(struct backend));
strlcpy(ret->hostname, server, sizeof(ret->hostname));
ret->timeout = NULL;
}
else
ret = ret_backend;
if (server[0] == '/') { /* unix socket */
res0 = &hints;
memset(res0, 0, sizeof(struct addrinfo));
res0->ai_family = PF_UNIX;
res0->ai_socktype = SOCK_STREAM;
res0->ai_addr = (struct sockaddr *) &sunsock;
res0->ai_addrlen = sizeof(sunsock.sun_family) + strlen(server) + 1;
#ifdef SIN6_LEN
res0->ai_addrlen += sizeof(sunsock.sun_len);
sunsock.sun_len = res0->ai_addrlen;
#endif
sunsock.sun_family = AF_UNIX;
strlcpy(sunsock.sun_path, server, sizeof(sunsock.sun_path));
/* XXX set that we are preauthed */
/* change hostname to 'config_servername' */
strlcpy(ret->hostname, config_servername, sizeof(ret->hostname));
}
else { /* inet socket */
memset(&hints, 0, sizeof(hints));
hints.ai_family = PF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
err = getaddrinfo(server, prot->service, &hints, &res0);
if (err) {
syslog(LOG_ERR, "getaddrinfo(%s) failed: %s",
server, gai_strerror(err));
goto error;
}
}
/* Setup timeout */
timedout = 0;
action.sa_flags = 0;
action.sa_handler = timed_out;
sigemptyset(&action.sa_mask);
if(sigaction(SIGALRM, &action, NULL) < 0)
{
syslog(LOG_ERR, "Setting timeout in backend_connect failed: sigaction: %m");
/* continue anyway */
}
for (res = res0; res; res = res->ai_next) {
sock = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
if (sock < 0)
continue;
alarm(config_getint(IMAPOPT_CLIENT_TIMEOUT));
if (connect(sock, res->ai_addr, res->ai_addrlen) >= 0)
break;
if(errno == EINTR && timedout == 1)
errno = ETIMEDOUT;
close(sock);
sock = -1;
}
/* Remove timeout code */
alarm(0);
signal(SIGALRM, SIG_IGN);
if (sock < 0) {
if (res0 != &hints)
freeaddrinfo(res0);
syslog(LOG_ERR, "connect(%s) failed: %m", server);
goto error;
}
memcpy(&ret->addr, res->ai_addr, res->ai_addrlen);
if (res0 != &hints)
freeaddrinfo(res0);
ret->in = prot_new(sock, 0);
ret->out = prot_new(sock, 1);
ret->sock = sock;
prot_setflushonread(ret->in, ret->out);
ret->prot = prot;
/* use literal+ to send literals */
prot_setisclient(ret->in, 1);
prot_setisclient(ret->out, 1);
if (prot->banner.auto_capa) {
/* try to get the capabilities from the banner */
r = ask_capability(ret, /*dobanner*/1, AUTO_CAPA_BANNER);
if (r) {
/* found capabilities in banner -> don't ask */
ask = 0;
}
}
else {
do { /* read the initial greeting */
if (!prot_fgets(buf, sizeof(buf), ret->in)) {
syslog(LOG_ERR,
"backend_connect(): couldn't read initial greeting: %s",
ret->in->error ? ret->in->error : "(null)");
goto error;
}
} while (strncasecmp(buf, prot->banner.resp,
strlen(prot->banner.resp)));
strncpy(ret->banner, buf, 2048);
}
if (ask) {
/* get the capabilities */
ask_capability(ret, /*dobanner*/0, AUTO_CAPA_NO);
}
/* now need to authenticate to backend server,
unless we're doing LMTP/CSYNC on a UNIX socket (deliver/sync_client) */
if ((server[0] != '/') ||
(strcmp(prot->sasl_service, "lmtp") &&
strcmp(prot->sasl_service, "csync"))) {
char *old_mechlist = backend_get_cap_params(ret, CAPA_AUTH);
const char *my_status;
if ((r = backend_authenticate(ret, userid, cb, &my_status))) {
syslog(LOG_ERR, "couldn't authenticate to backend server: %s",
sasl_errstring(r, NULL, NULL));
free(old_mechlist);
goto error;
}
else {
const void *ssf;
sasl_getprop(ret->saslconn, SASL_SSF, &ssf);
if (*((sasl_ssf_t *) ssf)) {
/* if we have a SASL security layer, compare SASL mech lists
before/after AUTH to check for a MITM attack */
char *new_mechlist;
int auto_capa = (prot->sasl_cmd.auto_capa == AUTO_CAPA_AUTH_SSF);
if (!strcmp(prot->service, "sieve")) {
/* XXX Hack to handle ManageSieve servers.
* No way to tell from protocol if server will
* automatically send capabilities, so we treat it
* as optional.
*/
char ch;
/* wait and probe for possible auto-capability response */
usleep(250000);
prot_NONBLOCK(ret->in);
if ((ch = prot_getc(ret->in)) != EOF) {
prot_ungetc(ch, ret->in);
} else {
auto_capa = AUTO_CAPA_AUTH_NO;
}
prot_BLOCK(ret->in);
}
ask_capability(ret, /*dobanner*/0, auto_capa);
new_mechlist = backend_get_cap_params(ret, CAPA_AUTH);
if (new_mechlist &&
old_mechlist &&
strcmp(new_mechlist, old_mechlist)) {
syslog(LOG_ERR, "possible MITM attack:"
"list of available SASL mechanisms changed");
free(new_mechlist);
free(old_mechlist);
goto error;
}
free(new_mechlist);
}
else if (prot->sasl_cmd.auto_capa == AUTO_CAPA_AUTH_OK) {
/* try to get the capabilities from the AUTH success response */
forget_capabilities(ret);
parse_capability(ret, my_status);
post_parse_capability(ret);
}
if (!(strcmp(prot->service, "imap") &&
(strcmp(prot->service, "pop3")))) {
parse_sessionid(my_status, rsessionid);
syslog(LOG_NOTICE, "proxy %s sessionid=<%s> remote=<%s>", userid, session_id(), rsessionid);
}
}
if (auth_status) *auth_status = my_status;
free(old_mechlist);
}
/* start compression if requested and both client/server support it */
if (config_getswitch(IMAPOPT_PROXY_COMPRESS) && ret &&
CAPA(ret, CAPA_COMPRESS) &&
prot->compress_cmd.cmd &&
do_compress(ret, &prot->compress_cmd)) {
syslog(LOG_ERR, "couldn't enable compression on backend server");
goto error;
}
return ret;
error:
forget_capabilities(ret);
if (ret->in) {
prot_free(ret->in);
ret->in = NULL;
}
if (ret->out) {
prot_free(ret->out);
ret->out = NULL;
}
if (sock >= 0)
close(sock);
if (ret->saslconn) {
sasl_dispose(&ret->saslconn);
ret->saslconn = NULL;
}
if (!ret_backend)
free(ret);
return NULL;
}
static int backend_login(struct backend *ret, const char *userid,
sasl_callback_t *cb, const char **auth_status,
int noauth)
{
int r = 0;
int ask = 1; /* should we explicitly ask for capabilities? */
char buf[2048];
struct protocol_t *prot = ret->prot;
if (prot->type != TYPE_STD) return -1;
if (prot->u.std.banner.auto_capa) {
/* try to get the capabilities from the banner */
r = ask_capability(ret, /*dobanner*/1, AUTO_CAPA_BANNER);
if (r) {
/* found capabilities in banner -> don't ask */
ask = 0;
}
}
else {
do { /* read the initial greeting */
if (!prot_fgets(buf, sizeof(buf), ret->in)) {
syslog(LOG_ERR,
"backend_login(): couldn't read initial greeting: %s",
ret->in->error ? ret->in->error : "(null)");
return -1;
}
} while (strncasecmp(buf, prot->u.std.banner.resp,
strlen(prot->u.std.banner.resp)));
xstrncpy(ret->banner, buf, 2048);
}
if (ask) {
/* get the capabilities */
ask_capability(ret, /*dobanner*/0, AUTO_CAPA_NO);
}
/* now need to authenticate to backend server,
unless we're doing LMTP/CSYNC on a UNIX socket (deliver/sync_client) */
if (!noauth) {
char *old_mechlist = backend_get_cap_params(ret, CAPA_AUTH);
const char *my_status;
if ((r = backend_authenticate(ret, userid, cb, &my_status))) {
syslog(LOG_ERR, "couldn't authenticate to backend server: %s",
sasl_errstring(r, NULL, NULL));
free(old_mechlist);
return -1;
}
else {
const void *ssf;
sasl_getprop(ret->saslconn, SASL_SSF, &ssf);
if (*((sasl_ssf_t *) ssf)) {
/* if we have a SASL security layer, compare SASL mech lists
before/after AUTH to check for a MITM attack */
char *new_mechlist;
int auto_capa = (prot->u.std.sasl_cmd.auto_capa == AUTO_CAPA_AUTH_SSF);
if (!strcmp(prot->service, "sieve")) {
/* XXX Hack to handle ManageSieve servers.
* No way to tell from protocol if server will
* automatically send capabilities, so we treat it
* as optional.
*/
char ch;
/* wait and probe for possible auto-capability response */
usleep(250000);
prot_NONBLOCK(ret->in);
if ((ch = prot_getc(ret->in)) != EOF) {
prot_ungetc(ch, ret->in);
} else {
auto_capa = AUTO_CAPA_AUTH_NO;
}
prot_BLOCK(ret->in);
}
ask_capability(ret, /*dobanner*/0, auto_capa);
new_mechlist = backend_get_cap_params(ret, CAPA_AUTH);
if (new_mechlist &&
old_mechlist &&
strcmp(new_mechlist, old_mechlist)) {
syslog(LOG_ERR, "possible MITM attack:"
"list of available SASL mechanisms changed");
if (new_mechlist) free(new_mechlist);
if (old_mechlist) free(old_mechlist);
return -1;
}
free(new_mechlist);
}
else if (prot->u.std.sasl_cmd.auto_capa == AUTO_CAPA_AUTH_OK) {
/* try to get the capabilities from the AUTH success response */
forget_capabilities(ret);
parse_capability(ret, my_status);
post_parse_capability(ret);
}
if (!(strcmp(prot->service, "imap") &&
(strcmp(prot->service, "pop3")))) {
char rsessionid[MAX_SESSIONID_SIZE];
parse_sessionid(my_status, rsessionid);
syslog(LOG_NOTICE, "auditlog: proxy %s sessionid=<%s> remote=<%s>", userid, session_id(), rsessionid);
}
}
if (auth_status) *auth_status = my_status;
free(old_mechlist);
}
/* start compression if requested and both client/server support it */
if (config_getswitch(IMAPOPT_PROXY_COMPRESS) &&
CAPA(ret, CAPA_COMPRESS) &&
prot->u.std.compress_cmd.cmd) {
r = do_compress(ret, &prot->u.std.compress_cmd);
if (r) {
syslog(LOG_NOTICE, "couldn't enable compression on backend server: %s", error_message(r));
r = 0; /* not a fail-level error */
}
}
return 0;
}
