modules/m_sasl.c

   1 /* modules/m_sasl.c
   2  *   Copyright (C) 2006 Michael Tharp <gxti@partiallystapled.com>
   3  *   Copyright (C) 2006 charybdis development team
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met:
   8  *
   9  * 1.Redistributions of source code must retain the above copyright notice,
  10  *   this list of conditions and the following disclaimer.
  11  * 2.Redistributions in binary form must reproduce the above copyright
  12  *   notice, this list of conditions and the following disclaimer in the
  13  *   documentation and/or other materials provided with the distribution.
  14  * 3.The name of the author may not be used to endorse or promote products
  15  *   derived from this software without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  20  * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
  21  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  22  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  23  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  25  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  26  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  27  * POSSIBILITY OF SUCH DAMAGE.
  28  */
  29
  30 #include "stdinc.h"
  31
  32 #include "client.h"
  33 #include "hash.h"
  34 #include "send.h"
  35 #include "msg.h"
  36 #include "modules.h"
  37 #include "numeric.h"
  38 #include "reject.h"
  39 #include "s_serv.h"
  40 #include "s_stats.h"
  41 #include "string.h"
  42 #include "s_newconf.h"
  43 #include "s_conf.h"
  44
  45 static const char sasl_desc[] = "Provides SASL authentication support";
  46
  47 static void m_authenticate(struct MsgBuf *, struct Client *, struct Client *, int, const char **);
  48 static void me_sasl(struct MsgBuf *, struct Client *, struct Client *, int, const char **);
  49 static void me_mechlist(struct MsgBuf *, struct Client *, struct Client *, int, const char **);
  50
  51 static void abort_sasl(struct Client *);
  52 static void abort_sasl_exit(hook_data_client_exit *);
  53
  54 static void advertise_sasl(struct Client *);
  55 static void advertise_sasl_exit(hook_data_client_exit *);
  56
  57 static unsigned int CLICAP_SASL = 0;
  58 static char mechlist_buf[BUFSIZE];
  59
  60 struct Message authenticate_msgtab = {
  61         "AUTHENTICATE", 0, 0, 0, 0,
  62         {{m_authenticate, 2}, {m_authenticate, 2}, mg_ignore, mg_ignore, mg_ignore, {m_authenticate, 2}}
  63 };
  64 struct Message sasl_msgtab = {
  65         "SASL", 0, 0, 0, 0,
  66         {mg_ignore, mg_ignore, mg_ignore, mg_ignore, {me_sasl, 5}, mg_ignore}
  67 };
  68 struct Message mechlist_msgtab = {
  69         "MECHLIST", 0, 0, 0, 0,
  70         {mg_ignore, mg_ignore, mg_ignore, mg_ignore, {me_mechlist, 2}, mg_ignore}
  71 };
  72
  73 mapi_clist_av1 sasl_clist[] = {
  74         &authenticate_msgtab, &sasl_msgtab, &mechlist_msgtab, NULL
  75 };
  76 mapi_hfn_list_av1 sasl_hfnlist[] = {
  77         { "new_local_user",     (hookfn) abort_sasl },
  78         { "client_exit",        (hookfn) abort_sasl_exit },
  79         { "new_remote_user",    (hookfn) advertise_sasl },
  80         { "client_exit",        (hookfn) advertise_sasl_exit },
  81         { NULL, NULL }
  82 };
  83
  84 static bool
  85 sasl_visible(struct Client *client_p)
  86 {
  87         struct Client *agent_p = NULL;
  88
  89         if (ConfigFileEntry.sasl_service)
  90                 agent_p = find_named_client(ConfigFileEntry.sasl_service);
  91
  92         return agent_p != NULL && IsService(agent_p);
  93 }
  94
  95 static const char *
  96 sasl_data(struct Client *client_p)
  97 {
  98         return *mechlist_buf != 0 ? mechlist_buf : NULL;
  99 }
 100
 101 static struct ClientCapability capdata_sasl = {
 102         .visible = sasl_visible,
 103         .data = sasl_data,
 104         .flags = CLICAP_FLAGS_STICKY,
 105 };
 106
 107 static int
 108 _modinit(void)
 109 {
 110         memset(mechlist_buf, 0, sizeof mechlist_buf);
 111         CLICAP_SASL = capability_put(cli_capindex, "sasl", &capdata_sasl);
 112         return 0;
 113 }
 114
 115 static void
 116 _moddeinit(void)
 117 {
 118         capability_orphan(cli_capindex, "sasl");
 119 }
 120
 121 DECLARE_MODULE_AV2(sasl, _modinit, _moddeinit, sasl_clist, NULL, sasl_hfnlist, NULL, NULL, sasl_desc);
 122
 123 static void
 124 m_authenticate(struct MsgBuf *msgbuf_p, struct Client *client_p, struct Client *source_p,
 125         int parc, const char *parv[])
 126 {
 127         struct Client *agent_p = NULL;
 128         struct Client *saslserv_p = NULL;
 129
 130         /* They really should use CAP for their own sake. */
 131         if(!IsCapable(source_p, CLICAP_SASL))
 132                 return;
 133
 134         if(source_p->localClient->sasl_next_retry > rb_current_time())
 135         {
 136                 sendto_one(source_p, form_str(RPL_LOAD2HI), me.name, EmptyString(source_p->name) ? "*" : source_p->name, msgbuf_p->cmd);
 137                 return;
 138         }
 139
 140         if(strlen(client_p->id) == 3)
 141         {
 142                 exit_client(client_p, client_p, client_p, "Mixing client and server protocol");
 143                 return;
 144         }
 145
 146         if (*parv[1] == ':' || strchr(parv[1], ' '))
 147         {
 148                 exit_client(client_p, client_p, client_p, "Malformed AUTHENTICATE");
 149                 return;
 150         }
 151
 152         saslserv_p = find_named_client(ConfigFileEntry.sasl_service);
 153         if(saslserv_p == NULL || !IsService(saslserv_p))
 154         {
 155                 sendto_one(source_p, form_str(ERR_SASLABORTED), me.name, EmptyString(source_p->name) ? "*" : source_p->name);
 156                 return;
 157         }
 158
 159         if(source_p->localClient->sasl_complete)
 160         {
 161                 *source_p->localClient->sasl_agent = '\0';
 162                 source_p->localClient->sasl_complete = 0;
 163         }
 164
 165         if(strlen(parv[1]) > 400)
 166         {
 167                 sendto_one(source_p, form_str(ERR_SASLTOOLONG), me.name, EmptyString(source_p->name) ? "*" : source_p->name);
 168                 return;
 169         }
 170
 171         if(!*source_p->id)
 172         {
 173                 /* Allocate a UID. */
 174                 rb_strlcpy(source_p->id, generate_uid(), sizeof(source_p->id));
 175                 add_to_id_hash(source_p->id, source_p);
 176         }
 177
 178         if(*source_p->localClient->sasl_agent)
 179                 agent_p = find_id(source_p->localClient->sasl_agent);
 180
 181         if(agent_p == NULL)
 182         {
 183                 sendto_one(saslserv_p, ":%s ENCAP %s SASL %s %s H %s %s",
 184                                         me.id, saslserv_p->servptr->name, source_p->id, saslserv_p->id,
 185                                         source_p->host, source_p->sockhost);
 186
 187                 if (source_p->certfp != NULL)
 188                         sendto_one(saslserv_p, ":%s ENCAP %s SASL %s %s S %s %s",
 189                                                 me.id, saslserv_p->servptr->name, source_p->id, saslserv_p->id,
 190                                                 parv[1], source_p->certfp);
 191                 else
 192                         sendto_one(saslserv_p, ":%s ENCAP %s SASL %s %s S %s",
 193                                                 me.id, saslserv_p->servptr->name, source_p->id, saslserv_p->id,
 194                                                 parv[1]);
 195
 196                 rb_strlcpy(source_p->localClient->sasl_agent, saslserv_p->id, IDLEN);
 197         }
 198         else
 199                 sendto_one(agent_p, ":%s ENCAP %s SASL %s %s C %s",
 200                                 me.id, agent_p->servptr->name, source_p->id, agent_p->id,
 201                                 parv[1]);
 202         source_p->localClient->sasl_out++;
 203 }
 204
 205 static void
 206 me_sasl(struct MsgBuf *msgbuf_p, struct Client *client_p, struct Client *source_p,
 207         int parc, const char *parv[])
 208 {
 209         struct Client *target_p, *agent_p;
 210
 211         /* Let propagate if not addressed to us, or if broadcast.
 212          * Only SASL agents can answer global requests.
 213          */
 214         if(strncmp(parv[2], me.id, 3))
 215                 return;
 216
 217         if((target_p = find_id(parv[2])) == NULL)
 218                 return;
 219
 220         if((agent_p = find_id(parv[1])) == NULL)
 221                 return;
 222
 223         if(source_p != agent_p->servptr) /* WTF?! */
 224                 return;
 225
 226         /* We only accept messages from SASL agents; these must have umode +S
 227          * (so the server must be listed in a service{} block).
 228          */
 229         if(!IsService(agent_p))
 230                 return;
 231
 232         /* Reject if someone has already answered. */
 233         if(*target_p->localClient->sasl_agent && strncmp(parv[1], target_p->localClient->sasl_agent, IDLEN))
 234                 return;
 235         else if(!*target_p->localClient->sasl_agent)
 236                 rb_strlcpy(target_p->localClient->sasl_agent, parv[1], IDLEN);
 237
 238         if(*parv[3] == 'C')
 239         {
 240                 sendto_one(target_p, "AUTHENTICATE %s", parv[4]);
 241                 target_p->localClient->sasl_messages++;
 242         }
 243         else if(*parv[3] == 'D')
 244         {
 245                 if(*parv[4] == 'F')
 246                 {
 247                         sendto_one(target_p, form_str(ERR_SASLFAIL), me.name, EmptyString(target_p->name) ? "*" : target_p->name);
 248                         /* Failures with zero messages are just "unknown mechanism" errors; don't count those. */
 249                         if(target_p->localClient->sasl_messages > 0)
 250                         {
 251                                 if(*target_p->name)
 252                                 {
 253                                         /* Allow 2 tries before rate-limiting as some clients try EXTERNAL
 254                                          * then PLAIN right after it if the auth failed, causing the client to be
 255                                          * rate-limited immediately and not being able to login with SASL.
 256                                          */
 257                                         if (target_p->localClient->sasl_failures++ > 0)
 258                                                 target_p->localClient->sasl_next_retry = rb_current_time() + (1 << MIN(target_p->localClient->sasl_failures + 1, 8));
 259                                 }
 260                                 else if(throttle_add((struct sockaddr*)&target_p->localClient->ip))
 261                                 {
 262                                         exit_client(target_p, target_p, &me, "Too many failed authentication attempts");
 263                                         return;
 264                                 }
 265                         }
 266                 }
 267                 else if(*parv[4] == 'S')
 268                 {
 269                         sendto_one(target_p, form_str(RPL_SASLSUCCESS), me.name, EmptyString(target_p->name) ? "*" : target_p->name);
 270                         target_p->localClient->sasl_failures = 0;
 271                         target_p->localClient->sasl_complete = 1;
 272                         ServerStats.is_ssuc++;
 273                 }
 274                 *target_p->localClient->sasl_agent = '\0'; /* Blank the stored agent so someone else can answer */
 275                 target_p->localClient->sasl_messages = 0;
 276         }
 277         else if(*parv[3] == 'M')
 278                 sendto_one(target_p, form_str(RPL_SASLMECHS), me.name, EmptyString(target_p->name) ? "*" : target_p->name, parv[4]);
 279 }
 280
 281 static void
 282 me_mechlist(struct MsgBuf *msgbuf_p, struct Client *client_p, struct Client *source_p,
 283             int parc, const char *parv[])
 284 {
 285         rb_strlcpy(mechlist_buf, parv[1], sizeof mechlist_buf);
 286 }
 287
 288 /* If the client never finished authenticating but is
 289  * registering anyway, abort the exchange.
 290  */
 291 static void
 292 abort_sasl(struct Client *data)
 293 {
 294         if(data->localClient->sasl_out == 0 || data->localClient->sasl_complete)
 295                 return;
 296
 297         data->localClient->sasl_out = data->localClient->sasl_complete = 0;
 298         ServerStats.is_sbad++;
 299
 300         if(!IsClosing(data))
 301                 sendto_one(data, form_str(ERR_SASLABORTED), me.name, EmptyString(data->name) ? "*" : data->name);
 302
 303         if(*data->localClient->sasl_agent)
 304         {
 305                 struct Client *agent_p = find_id(data->localClient->sasl_agent);
 306                 if(agent_p)
 307                 {
 308                         sendto_one(agent_p, ":%s ENCAP %s SASL %s %s D A", me.id, agent_p->servptr->name,
 309                                         data->id, agent_p->id);
 310                         return;
 311                 }
 312         }
 313
 314         sendto_server(NULL, NULL, CAP_TS6|CAP_ENCAP, NOCAPS, ":%s ENCAP * SASL %s * D A", me.id,
 315                         data->id);
 316 }
 317
 318 static void
 319 abort_sasl_exit(hook_data_client_exit *data)
 320 {
 321         if (data->target->localClient)
 322                 abort_sasl(data->target);
 323 }
 324
 325 static void
 326 advertise_sasl(struct Client *client_p)
 327 {
 328         if (!ConfigFileEntry.sasl_service)
 329                 return;
 330
 331         if (irccmp(client_p->name, ConfigFileEntry.sasl_service))
 332                 return;
 333
 334         sendto_local_clients_with_capability(CLICAP_CAP_NOTIFY, ":%s CAP * NEW :sasl", me.name);
 335 }
 336
 337 static void
 338 advertise_sasl_exit(hook_data_client_exit *data)
 339 {
 340         if (!ConfigFileEntry.sasl_service)
 341                 return;
 342
 343         if (irccmp(data->target->name, ConfigFileEntry.sasl_service))
 344                 return;
 345
 346         sendto_local_clients_with_capability(CLICAP_CAP_NOTIFY, ":%s CAP * DEL :sasl", me.name);
 347 }