// L2TPNS Radius Stuff
-char const *cvs_id_radius = "$Id: radius.c,v 1.49 2006-04-13 11:14:35 bodea Exp $";
-
#include <time.h>
#include <stdio.h>
#include <sys/types.h>
#include <ctype.h>
#include <netinet/in.h>
#include <errno.h>
+
#include "md5.h"
#include "constants.h"
#include "l2tpns.h"
#include "util.h"
#include "cluster.h"
+#include "l2tplac.h"
+#include "pppoe.h"
+
extern radiust *radius;
extern sessiont *session;
extern tunnelt *tunnel;
void initrad(void)
{
int i;
+ uint16_t port = 0;
+ uint16_t min = config->radius_bind_min;
+ uint16_t max = config->radius_bind_max;
+ int inc = 1;
+ struct sockaddr_in addr;
+
+ if (min)
+ {
+ port = min;
+ if (!max)
+ max = ~0 - 1;
+ }
+ else if (max) /* no minimum specified, bind from max down */
+ {
+ port = max;
+ min = 1;
+ inc = -1;
+ }
+
LOG(3, 0, 0, "Creating %d sockets for RADIUS queries\n", RADIUS_FDS);
radfds = calloc(sizeof(int), RADIUS_FDS);
for (i = 0; i < RADIUS_FDS; i++)
radfds[i] = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
flags = fcntl(radfds[i], F_GETFL, 0);
fcntl(radfds[i], F_SETFL, flags | O_NONBLOCK);
+
+ if (port)
+ {
+ int b;
+
+ memset(&addr, 0, sizeof(addr));
+ addr.sin_family = AF_INET;
+ addr.sin_addr.s_addr = INADDR_ANY;
+
+ do {
+ addr.sin_port = htons(port);
+ if ((b = bind(radfds[i], (struct sockaddr *) &addr, sizeof(addr))) < 0)
+ {
+ if ((port += inc) < min || port > max)
+ {
+ LOG(0, 0, 0, "Can't bind RADIUS socket in range %u-%u\n", min, max);
+ exit(1);
+ }
+ }
+ } while (b < 0);
+ }
}
}
return;
}
- if (state != RADIUSAUTH && !config->radius_accounting)
+ if (state != RADIUSAUTH && state != RADIUSJUSTAUTH && !config->radius_accounting)
{
// Radius accounting is turned off
radiusclear(r, s);
{
if (s)
{
- if (state == RADIUSAUTH)
+ if (state == RADIUSAUTH || state == RADIUSJUSTAUTH)
sessionshutdown(s, "RADIUS timeout.", CDN_ADMIN_DISC, TERM_REAUTHENTICATION_FAILURE);
else
{
switch (state)
{
case RADIUSAUTH:
+ case RADIUSJUSTAUTH:
b[0] = AccessRequest; // access request
break;
case RADIUSSTART:
}
b[1] = r >> RADIUS_SHIFT; // identifier
memcpy(b + 4, radius[r].auth, 16);
+
p = b + 20;
if (s)
{
strcpy((char *) p + 2, session[s].user);
p += p[1];
}
- if (state == RADIUSAUTH)
+ if (state == RADIUSAUTH || state == RADIUSJUSTAUTH)
{
if (radius[r].chap)
{
}
}
+ if (session[s].classlen) {
+ *p = 25; // class
+ p[1] = session[s].classlen + 2;
+ memcpy(p + 2, session[s].class, session[s].classlen);
+ p += p[1];
+ }
+
{
struct param_radius_account acct = { &tunnel[session[s].tunnel], &session[s], &p };
run_plugins(PLUGIN_RADIUS_ACCOUNT, &acct);
}
}
}
+
if (s)
{
*p = 5; // NAS-Port
*p = 6; // Service-Type
p[1] = 6;
- *(uint32_t *) (p + 2) = htonl(2); // Framed-User
+ *(uint32_t *) (p + 2) = htonl((state == RADIUSJUSTAUTH ? 8 : 2)); // Authenticate only or Framed-User respectevily
p += p[1];
*p = 7; // Framed-Protocol
- p[1] = 6;
- *(uint32_t *) (p + 2) = htonl(1); // PPP
+ p[1] = htonl((state == RADIUSJUSTAUTH ? 0 : 6));
+ *(uint32_t *) (p + 2) = htonl((state == RADIUSJUSTAUTH ? 0 : 1)); // PPP
p += p[1];
- }
- if (s && session[s].ip)
- {
- *p = 8; // Framed-IP-Address
- p[1] = 6;
- *(uint32_t *) (p + 2) = htonl(session[s].ip);
- p += p[1];
- }
- if (s && session[s].route[0].ip)
- {
- int r;
- for (r = 0; s && r < MAXROUTE && session[s].route[r].ip; r++)
+
+ if (session[s].ip)
{
- int width = 32;
- if (session[s].route[r].mask)
+ *p = 8; // Framed-IP-Address
+ p[1] = 6;
+ *(uint32_t *) (p + 2) = htonl(session[s].ip);
+ p += p[1];
+ }
+
+ if (session[s].route[0].ip)
+ {
+ int r;
+ for (r = 0; s && r < MAXROUTE && session[s].route[r].ip; r++)
{
- int mask = session[s].route[r].mask;
- while (!(mask & 1))
- {
- width--;
- mask >>= 1;
- }
+ *p = 22; // Framed-Route
+ p[1] = sprintf((char *) p + 2, "%s/%d %s 1",
+ fmtaddr(htonl(session[s].route[r].ip), 0),
+ session[s].route[r].prefixlen,
+ fmtaddr(htonl(session[s].ip), 1)) + 2;
+
+ p += p[1];
}
+ }
- *p = 22; // Framed-Route
- p[1] = sprintf((char *) p + 2, "%s/%d %s 1",
- fmtaddr(htonl(session[s].route[r].ip), 0),
- width, fmtaddr(htonl(session[s].ip), 1)) + 2;
+ if (session[s].session_timeout)
+ {
+ *p = 27; // Session-Timeout
+ p[1] = 6;
+ *(uint32_t *) (p + 2) = htonl(session[s].session_timeout);
+ p += p[1];
+ }
+ if (session[s].idle_timeout)
+ {
+ *p = 28; // Idle-Timeout
+ p[1] = 6;
+ *(uint32_t *) (p + 2) = htonl(session[s].idle_timeout);
+ p += p[1];
+ }
+
+ if (*session[s].called)
+ {
+ *p = 30; // called
+ p[1] = strlen(session[s].called) + 2;
+ strcpy((char *) p + 2, session[s].called);
+ p += p[1];
+ }
+
+ if (*session[s].calling)
+ {
+ *p = 31; // calling
+ p[1] = strlen(session[s].calling) + 2;
+ strcpy((char *) p + 2, session[s].calling);
p += p[1];
}
}
- if (*session[s].called)
- {
- *p = 30; // called
- p[1] = strlen(session[s].called) + 2;
- strcpy((char *) p + 2, session[s].called);
- p += p[1];
- }
- if (*session[s].calling)
- {
- *p = 31; // calling
- p[1] = strlen(session[s].calling) + 2;
- strcpy((char *) p + 2, session[s].calling);
- p += p[1];
- }
+
// NAS-IP-Address
*p = 4;
p[1] = 6;
// All AVpairs added
*(uint16_t *) (b + 2) = htons(p - b);
- if (state != RADIUSAUTH)
+ if (state != RADIUSAUTH && state != RADIUSJUSTAUTH)
{
// Build auth for accounting packet
calc_auth(b, p - b, zero, b + 4);
// get radius port
uint16_t port = config->radiusport[(radius[r].try - 1) % config->numradiusservers];
// assume RADIUS accounting port is the authentication port +1
- addr.sin_port = htons((state == RADIUSAUTH) ? port : port+1);
+ addr.sin_port = htons((state == RADIUSAUTH || state == RADIUSJUSTAUTH) ? port : port+1);
}
LOG_HEX(5, "RADIUS Send", b, (p - b));
uint8_t routes = 0;
int r_code;
int r_id;
+ int OpentunnelReq = 0;
CSTAT(processrad);
LOG(1, s, session[s].tunnel, " Unexpected RADIUS response\n");
return;
}
- if (radius[r].state != RADIUSAUTH && radius[r].state != RADIUSSTART
+ if (radius[r].state != RADIUSAUTH && radius[r].state != RADIUSJUSTAUTH && radius[r].state != RADIUSSTART
&& radius[r].state != RADIUSSTOP && radius[r].state != RADIUSINTERIM)
{
LOG(1, s, session[s].tunnel, " Unexpected RADIUS response\n");
return; // Do nothing. On timeout, it will try the next radius server.
}
- if ((radius[r].state == RADIUSAUTH && r_code != AccessAccept && r_code != AccessReject) ||
+ if (((radius[r].state == RADIUSAUTH ||radius[r].state == RADIUSJUSTAUTH) && r_code != AccessAccept && r_code != AccessReject) ||
((radius[r].state == RADIUSSTART || radius[r].state == RADIUSSTOP || radius[r].state == RADIUSINTERIM) && r_code != AccountingResponse))
{
LOG(1, s, session[s].tunnel, " Unexpected RADIUS response %s\n", radius_code(r_code));
// care off finishing the radius session if that's really correct.
}
- if (radius[r].state == RADIUSAUTH)
+ if (radius[r].state == RADIUSAUTH || radius[r].state == RADIUSJUSTAUTH)
{
// run post-auth plugin
struct param_post_auth packet = {
run_plugins(PLUGIN_POST_AUTH, &packet);
r_code = packet.auth_allowed ? AccessAccept : AccessReject;
+#ifndef LAC
// process auth response
if (radius[r].chap)
{
// CHAP
- uint8_t *p = makeppp(b, sizeof(b), 0, 0, s, t, PPPCHAP);
+ uint8_t *p = makeppp(b, sizeof(b), 0, 0, s, t, PPPCHAP, 0, 0, 0);
if (!p) return; // Abort!
*p = (r_code == AccessAccept) ? 3 : 4; // ack/nak
else
{
// PAP
- uint8_t *p = makeppp(b, sizeof(b), 0, 0, s, t, PPPPAP);
+ uint8_t *p = makeppp(b, sizeof(b), 0, 0, s, t, PPPPAP, 0, 0, 0);
if (!p) return; // Abort!
// ack/nak
LOG(3, s, session[s].tunnel, " PAP User %s authentication %s.\n", session[s].user,
(r_code == AccessAccept) ? "allowed" : "denied");
}
+#endif
if (r_code == AccessAccept)
{
// Extract IP, routes, etc
uint8_t *p = buf + 20;
uint8_t *e = buf + len;
+ uint8_t tag;
+ uint8_t strtemp[256];
+ lac_reset_rad_tag_tunnel_ctxt();
+
for (; p + 2 <= e && p[1] && p + p[1] <= e; p += p[1])
{
+ if (*p == 26 && p[1] >= 7)
+ {
+ // Vendor-Specific Attribute
+ uint32_t vendor = ntohl(*(int *)(p + 2));
+ uint8_t attrib = *(p + 6);
+ int attrib_length = *(p + 7) - 2;
+
+ LOG(4, s, session[s].tunnel, " Radius reply contains Vendor-Specific. Vendor=%u Attrib=%u Length=%d\n", vendor, attrib, attrib_length);
+ if (vendor == 9 && attrib == 1) // Cisco-AVPair
+ {
+ if (attrib_length < 0) continue;
+ LOG(3, s, session[s].tunnel, " Cisco-AVPair value: %.*s\n",
+ attrib_length, p + 8);
+
+ handle_avpair(s, p + 8, attrib_length);
+ continue;
+ }
+ else if (vendor == 529 && attrib >= 135 && attrib <= 136) // Ascend
+ {
+ // handle old-format ascend DNS attributes below
+ p += 6;
+ }
+ else
+ {
+ LOG(3, s, session[s].tunnel, " Unknown vendor-specific\n");
+ continue;
+ }
+ }
+
if (*p == 8)
{
// Framed-IP-Address
else if (*p == 22)
{
// Framed-Route
- in_addr_t ip = 0, mask = 0;
+ in_addr_t ip = 0;
uint8_t u = 0;
uint8_t bits = 0;
uint8_t *n = p + 2;
n++;
while (n < e && isdigit(*n))
bits = bits * 10 + *n++ - '0';
- mask = (( -1) << (32 - bits));
}
else if ((ip >> 24) < 128)
- mask = 0xFF0000;
+ bits = 8;
else if ((ip >> 24) < 192)
- mask = 0xFFFF0000;
+ bits = 16;
else
- mask = 0xFFFFFF00;
+ bits = 24;
if (routes == MAXROUTE)
{
}
else if (ip)
{
- LOG(3, s, session[s].tunnel, " Radius reply contains route for %s/%s\n",
- fmtaddr(htonl(ip), 0), fmtaddr(htonl(mask), 1));
+ LOG(3, s, session[s].tunnel, " Radius reply contains route for %s/%d\n",
+ fmtaddr(htonl(ip), 0), bits);
session[s].route[routes].ip = ip;
- session[s].route[routes].mask = mask;
+ session[s].route[routes].prefixlen = bits;
routes++;
}
}
ip_filters[f].used++;
}
}
- else if (*p == 26 && p[1] >= 7)
+ else if (*p == 27)
{
- // Vendor-Specific Attribute
- int vendor = ntohl(*(int *)(p + 2));
- char attrib = *(p + 6);
- int attrib_length = *(p + 7) - 2;
-
- LOG(3, s, session[s].tunnel, " Radius reply contains Vendor-Specific. Vendor=%d Attrib=%d Length=%d\n", vendor, attrib, attrib_length);
- if (vendor != 9 || attrib != 1)
- {
- LOG(3, s, session[s].tunnel, " Unknown vendor-specific\n");
- continue;
- }
-
- if (attrib_length > 0)
- {
- LOG(3, s, session[s].tunnel, " Cisco-AVPair value: %.*s\n",
- attrib_length, p + 8);
-
- handle_avpair(s, p + 8, attrib_length);
- }
+ // Session-Timeout
+ if (p[1] < 6) continue;
+ session[s].session_timeout = ntohl(*(uint32_t *)(p + 2));
+ LOG(3, s, session[s].tunnel, " Radius reply contains Session-Timeout = %u\n", session[s].session_timeout);
+ if(!session[s].session_timeout && config->kill_timedout_sessions)
+ sessionshutdown(s, "Session timeout is zero", CDN_ADMIN_DISC, 0);
+ }
+ else if (*p == 28)
+ {
+ // Idle-Timeout
+ if (p[1] < 6) continue;
+ session[s].idle_timeout = ntohl(*(uint32_t *)(p + 2));
+ LOG(3, s, session[s].tunnel, " Radius reply contains Idle-Timeout = %u\n", session[s].idle_timeout);
}
else if (*p == 99)
{
session[s].ipv6prefixlen = prefixlen;
}
}
+ else if (*p == 25)
+ {
+ // Class
+ if (p[1] < 3) continue;
+ session[s].classlen = p[1] - 2;
+ if (session[s].classlen > MAXCLASS)
+ session[s].classlen = MAXCLASS;
+ memcpy(session[s].class, p + 2, session[s].classlen);
+ }
+ else if (*p == 64)
+ {
+ // Tunnel-Type
+ if (p[1] != 6) continue;
+ tag = p[2];
+ LOG(3, s, session[s].tunnel, " Radius reply Tunnel-Type:%d %d\n",
+ tag, ntohl(*(uint32_t *)(p + 2)) & 0xFFFFFF);
+ // Fill context
+ lac_set_rad_tag_tunnel_type(tag, ntohl(*(uint32_t *)(p + 2)) & 0xFFFFFF);
+ /* Request open tunnel to remote LNS*/
+ OpentunnelReq = 1;
+ }
+ else if (*p == 65)
+ {
+ // Tunnel-Medium-Type
+ if (p[1] < 6) continue;
+ tag = p[2];
+ LOG(3, s, session[s].tunnel, " Radius reply Tunnel-Medium-Type:%d %d\n",
+ tag, ntohl(*(uint32_t *)(p + 2)) & 0xFFFFFF);
+ // Fill context
+ lac_set_rad_tag_tunnel_medium_type(tag, ntohl(*(uint32_t *)(p + 2)) & 0xFFFFFF);
+ }
+ else if (*p == 67)
+ {
+ // Tunnel-Server-Endpoint
+ if (p[1] < 3) continue;
+ tag = p[2];
+ //If the Tag field is greater than 0x1F,
+ // it SHOULD be interpreted as the first byte of the following String field.
+ memset(strtemp, 0, 256);
+ if (tag > 0x1F)
+ {
+ tag = 0;
+ memcpy(strtemp, (p + 2), p[1]-2);
+ }
+ else
+ memcpy(strtemp, (p + 3), p[1]-3);
+
+ LOG(3, s, session[s].tunnel, " Radius reply Tunnel-Server-Endpoint:%d %s\n", tag, strtemp);
+ // Fill context
+ lac_set_rad_tag_tunnel_serv_endpt(tag, (char *) strtemp);
+ }
+ else if (*p == 69)
+ {
+ // Tunnel-Password
+ size_t lentemp;
+
+ if (p[1] < 5) continue;
+ tag = p[2];
+
+ memset(strtemp, 0, 256);
+ lentemp = p[1]-3;
+ memcpy(strtemp, (p + 3), lentemp);
+ if (!rad_tunnel_pwdecode(strtemp, &lentemp, config->radiussecret, radius[r].auth))
+ {
+ LOG_HEX(3, "Error Decode Tunnel-Password, Dump Radius reponse:", p, p[1]);
+ continue;
+ }
+
+ LOG(3, s, session[s].tunnel, " Radius reply Tunnel-Password:%d %s\n", tag, strtemp);
+ if (strlen((char *) strtemp) > 63)
+ {
+ LOG(1, s, session[s].tunnel, "tunnel password is too long (>63)\n");
+ continue;
+ }
+ // Fill context
+ lac_set_rad_tag_tunnel_password(tag, (char *) strtemp);
+ }
+ else if (*p == 82)
+ {
+ // Tunnel-Assignment-Id
+ if (p[1] < 3) continue;
+ tag = p[2];
+ //If the Tag field is greater than 0x1F,
+ // it SHOULD be interpreted as the first byte of the following String field.
+ memset(strtemp, 0, 256);
+ if (tag > 0x1F)
+ {
+ tag = 0;
+ memcpy(strtemp, (p + 2), p[1]-2);
+ }
+ else
+ memcpy(strtemp, (p + 3), p[1]-3);
+
+ LOG(3, s, session[s].tunnel, " Radius reply Tunnel-Assignment-Id:%d %s\n", tag, strtemp);
+ // Fill context
+ lac_set_rad_tag_tunnel_assignment_id(tag, (char *) strtemp);
+ }
}
}
else if (r_code == AccessReject)
break;
}
+ if ((!config->disable_lac_func) && OpentunnelReq)
+ {
+ char assignment_id[256];
+ // Save radius tag context to conf
+ lac_save_rad_tag_tunnels(s);
+
+ memset(assignment_id, 0, 256);
+ if (!lac_rad_select_assignment_id(s, assignment_id))
+ break; // Error no assignment_id
+
+ LOG(3, s, session[s].tunnel, "Select Tunnel Remote LNS for assignment_id == %s\n", assignment_id);
+
+ if (lac_rad_forwardtoremotelns(s, assignment_id, session[s].user))
+ {
+ int ro;
+ // Sanity check, no local IP to session forwarded
+ session[s].ip = 0;
+ for (ro = 0; r < MAXROUTE && session[s].route[ro].ip; r++)
+ {
+ session[s].route[ro].ip = 0;
+ }
+ break;
+ }
+ }
+
+ // process auth response
+ if (radius[r].chap)
+ {
+ // CHAP
+ uint8_t *p = makeppp(b, sizeof(b), 0, 0, s, t, PPPCHAP, 0, 0, 0);
+ if (!p) return; // Abort!
+
+ *p = (r_code == AccessAccept) ? 3 : 4; // ack/nak
+ p[1] = radius[r].id;
+ *(uint16_t *) (p + 2) = ntohs(4); // no message
+ tunnelsend(b, (p - b) + 4, t); // send it
+
+ LOG(3, s, session[s].tunnel, " CHAP User %s authentication %s.\n", session[s].user,
+ (r_code == AccessAccept) ? "allowed" : "denied");
+ }
+ else
+ {
+ // PAP
+ uint8_t *p = makeppp(b, sizeof(b), 0, 0, s, t, PPPPAP, 0, 0, 0);
+ if (!p) return; // Abort!
+
+ // ack/nak
+ *p = r_code;
+ p[1] = radius[r].id;
+ *(uint16_t *) (p + 2) = ntohs(5);
+ p[4] = 0; // no message
+ tunnelsend(b, (p - b) + 5, t); // send it
+
+ LOG(3, s, session[s].tunnel, " PAP User %s authentication %s.\n", session[s].user,
+ (r_code == AccessAccept) ? "allowed" : "denied");
+ }
+
if (!session[s].dns1 && config->default_dns1)
{
session[s].dns1 = ntohl(config->default_dns1);
sendchap(s, t);
break;
case RADIUSAUTH: // sending auth to RADIUS server
+ case RADIUSJUSTAUTH: // sending auth to RADIUS server
case RADIUSSTART: // sending start accounting to RADIUS server
case RADIUSSTOP: // sending stop accounting to RADIUS server
case RADIUSINTERIM: // sending interim accounting to RADIUS server
if (sendtofrom(daefd, buf, len, MSG_DONTWAIT | MSG_NOSIGNAL, (struct sockaddr *) addr, alen, local) < 0)
LOG(0, 0, 0, "Error sending DAE response packet: %s\n", strerror(errno));
}
+
+// Decrypte the encrypted Tunnel Password.
+// Defined in RFC-2868.
+// the pl2tpsecret buffer must set to 256 characters.
+// return 0 on decoding error else length of decoded l2tpsecret
+int rad_tunnel_pwdecode(uint8_t *pl2tpsecret, size_t *pl2tpsecretlen,
+ const char *radiussecret, const uint8_t * auth)
+{
+ MD5_CTX ctx, oldctx;
+ hasht hash;
+ int secretlen;
+ unsigned i, n, len, decodedlen;
+
+/* 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 6 7
+* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Salt | Salt | String ..........
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+*/
+
+ len = *pl2tpsecretlen;
+
+ if (len < 2)
+ {
+ LOG(1, 0, 0, "tunnel password is too short, We need at least a salt\n");
+ return 0;
+ }
+
+ if (len <= 3)
+ {
+ pl2tpsecret[0] = 0;
+ *pl2tpsecretlen = 0;
+ LOG(1, 0, 0, "tunnel passwd is empty !!!\n");
+ return 0;
+ }
+
+ len -= 2; /* discount the salt */
+
+ //Use the secret to setup the decryption
+ secretlen = strlen(radiussecret);
+
+ MD5_Init(&ctx);
+ MD5_Update(&ctx, (void *) radiussecret, secretlen);
+ oldctx = ctx; /* save intermediate work */
+
+ // Set up the initial key:
+ // b(1) = MD5(radiussecret + auth + salt)
+ MD5_Update(&ctx, (void *) auth, 16);
+ MD5_Update(&ctx, pl2tpsecret, 2);
+
+ decodedlen = 0;
+ for (n = 0; n < len; n += 16)
+ {
+ int base = 0;
+
+ if (n == 0)
+ {
+ MD5_Final(hash, &ctx);
+
+ ctx = oldctx;
+
+ // the first octet, it's the 'data_len'
+ // Check is correct
+ decodedlen = pl2tpsecret[2] ^ hash[0];
+ if (decodedlen >= len)
+ {
+ LOG(1, 0, 0, "tunnel password is too long !!!\n");
+ return 0;
+ }
+
+ MD5_Update(&ctx, pl2tpsecret + 2, 16);
+ base = 1;
+ } else
+ {
+ MD5_Final(hash, &ctx);
+
+ ctx = oldctx;
+ MD5_Update(&ctx, pl2tpsecret + n + 2, 16);
+ }
+
+ for (i = base; i < 16; i++)
+ {
+ pl2tpsecret[n + i - 1] = pl2tpsecret[n + i + 2] ^ hash[i];
+ }
+ }
+
+ if (decodedlen > 239) decodedlen = 239;
+
+ *pl2tpsecretlen = decodedlen;
+ pl2tpsecret[decodedlen] = 0;
+
+ return decodedlen;
+};
projects / l2tpns.git / blobdiff