source/smbd/session.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    session handling for utmp and PAM
   4
   5    Copyright (C) tridge@samba.org       2001
   6    Copyright (C) abartlet@samba.org     2001
   7    Copyright (C) Gerald (Jerry) Carter  2006
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  21 */
  22
  23 /* a "session" is claimed when we do a SessionSetupX operation
  24    and is yielded when the corresponding vuid is destroyed.
  25
  26    sessions are used to populate utmp and PAM session structures
  27 */
  28
  29 #include "includes.h"
  30
  31 /********************************************************************
  32 ********************************************************************/
  33
  34 static struct db_context *session_db_ctx(void)
  35 {
  36         static struct db_context *ctx;
  37
  38         if (ctx)
  39                 return ctx;
  40
  41         ctx = db_open(NULL, lock_path("sessionid.tdb"), 0,
  42                       TDB_CLEAR_IF_FIRST|TDB_DEFAULT,
  43                       O_RDWR | O_CREAT, 0644);
  44         return ctx;
  45 }
  46
  47 bool session_init(void)
  48 {
  49         if (session_db_ctx() == NULL) {
  50                 DEBUG(1,("session_init: failed to open sessionid tdb\n"));
  51                 return False;
  52         }
  53
  54         return True;
  55 }
  56
  57 /********************************************************************
  58  called when a session is created
  59 ********************************************************************/
  60
  61 bool session_claim(user_struct *vuser)
  62 {
  63         TDB_DATA key, data;
  64         int i = 0;
  65         struct sessionid sessionid;
  66         struct server_id pid = procid_self();
  67         fstring keystr;
  68         const char * hostname;
  69         struct db_context *ctx;
  70         struct db_record *rec;
  71         NTSTATUS status;
  72         char addr[INET6_ADDRSTRLEN];
  73
  74         vuser->session_keystr = NULL;
  75
  76         /* don't register sessions for the guest user - its just too
  77            expensive to go through pam session code for browsing etc */
  78         if (vuser->server_info->guest) {
  79                 return True;
  80         }
  81
  82         if (!(ctx = session_db_ctx())) {
  83                 return False;
  84         }
  85
  86         ZERO_STRUCT(sessionid);
  87
  88         data.dptr = NULL;
  89         data.dsize = 0;
  90
  91         if (lp_utmp()) {
  92
  93                 for (i=1;i<MAX_SESSION_ID;i++) {
  94
  95                         /*
  96                          * This is very inefficient and needs fixing -- vl
  97                          */
  98
  99                         struct server_id sess_pid;
 100
 101                         snprintf(keystr, sizeof(keystr), "ID/%d", i);
 102                         key = string_term_tdb_data(keystr);
 103
 104                         rec = ctx->fetch_locked(ctx, NULL, key);
 105
 106                         if (rec == NULL) {
 107                                 DEBUG(1, ("Could not lock \"%s\"\n", keystr));
 108                                 return False;
 109                         }
 110
 111                         if (rec->value.dsize != sizeof(sessionid)) {
 112                                 DEBUG(1, ("Re-using invalid record\n"));
 113                                 break;
 114                         }
 115
 116                         memcpy(&sess_pid,
 117                                ((char *)rec->value.dptr)
 118                                + offsetof(struct sessionid, pid),
 119                                sizeof(sess_pid));
 120
 121                         if (!process_exists(sess_pid)) {
 122                                 DEBUG(5, ("%s has died -- re-using session\n",
 123                                           procid_str_static(&sess_pid)));
 124                                 break;
 125                         }
 126
 127                         TALLOC_FREE(rec);
 128                 }
 129
 130                 if (i == MAX_SESSION_ID) {
 131                         SMB_ASSERT(rec == NULL);
 132                         DEBUG(1,("session_claim: out of session IDs "
 133                                  "(max is %d)\n", MAX_SESSION_ID));
 134                         return False;
 135                 }
 136
 137                 snprintf(sessionid.id_str, sizeof(sessionid.id_str),
 138                          SESSION_UTMP_TEMPLATE, i);
 139         } else
 140         {
 141                 snprintf(keystr, sizeof(keystr), "ID/%s/%u",
 142                          procid_str_static(&pid), vuser->vuid);
 143                 key = string_term_tdb_data(keystr);
 144
 145                 rec = ctx->fetch_locked(ctx, NULL, key);
 146
 147                 if (rec == NULL) {
 148                         DEBUG(1, ("Could not lock \"%s\"\n", keystr));
 149                         return False;
 150                 }
 151
 152                 snprintf(sessionid.id_str, sizeof(sessionid.id_str),
 153                          SESSION_TEMPLATE, (long unsigned int)sys_getpid(),
 154                          vuser->vuid);
 155         }
 156
 157         SMB_ASSERT(rec != NULL);
 158
 159         /* If 'hostname lookup' == yes, then do the DNS lookup.  This is
 160            needed because utmp and PAM both expect DNS names
 161
 162            client_name() handles this case internally.
 163         */
 164
 165         hostname = client_name(get_client_fd());
 166         if (strcmp(hostname, "UNKNOWN") == 0) {
 167                 hostname = client_addr(get_client_fd(),addr,sizeof(addr));
 168         }
 169
 170         fstrcpy(sessionid.username, vuser->server_info->unix_name);
 171         fstrcpy(sessionid.hostname, hostname);
 172         sessionid.id_num = i;  /* Only valid for utmp sessions */
 173         sessionid.pid = pid;
 174         sessionid.uid = vuser->server_info->utok.uid;
 175         sessionid.gid = vuser->server_info->utok.gid;
 176         fstrcpy(sessionid.remote_machine, get_remote_machine_name());
 177         fstrcpy(sessionid.ip_addr_str,
 178                 client_addr(get_client_fd(),addr,sizeof(addr)));
 179         sessionid.connect_start = time(NULL);
 180
 181         if (!smb_pam_claim_session(sessionid.username, sessionid.id_str,
 182                                    sessionid.hostname)) {
 183                 DEBUG(1,("pam_session rejected the session for %s [%s]\n",
 184                                 sessionid.username, sessionid.id_str));
 185
 186                 TALLOC_FREE(rec);
 187                 return False;
 188         }
 189
 190         data.dptr = (uint8 *)&sessionid;
 191         data.dsize = sizeof(sessionid);
 192
 193         status = rec->store(rec, data, TDB_REPLACE);
 194
 195         TALLOC_FREE(rec);
 196
 197         if (!NT_STATUS_IS_OK(status)) {
 198                 DEBUG(1,("session_claim: unable to create session id "
 199                          "record: %s\n", nt_errstr(status)));
 200                 return False;
 201         }
 202
 203         if (lp_utmp()) {
 204                 sys_utmp_claim(sessionid.username, sessionid.hostname,
 205                                sessionid.ip_addr_str,
 206                                sessionid.id_str, sessionid.id_num);
 207         }
 208
 209         vuser->session_keystr = talloc_strdup(vuser, keystr);
 210         if (!vuser->session_keystr) {
 211                 DEBUG(0, ("session_claim:  talloc_strdup() failed for session_keystr\n"));
 212                 return False;
 213         }
 214         return True;
 215 }
 216
 217 /********************************************************************
 218  called when a session is destroyed
 219 ********************************************************************/
 220
 221 void session_yield(user_struct *vuser)
 222 {
 223         TDB_DATA key;
 224         struct sessionid sessionid;
 225         struct db_context *ctx;
 226         struct db_record *rec;
 227
 228         if (!(ctx = session_db_ctx())) return;
 229
 230         if (!vuser->session_keystr) {
 231                 return;
 232         }
 233
 234         key = string_term_tdb_data(vuser->session_keystr);
 235
 236         if (!(rec = ctx->fetch_locked(ctx, NULL, key))) {
 237                 return;
 238         }
 239
 240         if (rec->value.dsize != sizeof(sessionid))
 241                 return;
 242
 243         memcpy(&sessionid, rec->value.dptr, sizeof(sessionid));
 244
 245         if (lp_utmp()) {
 246                 sys_utmp_yield(sessionid.username, sessionid.hostname,
 247                                sessionid.ip_addr_str,
 248                                sessionid.id_str, sessionid.id_num);
 249         }
 250
 251         smb_pam_close_session(sessionid.username, sessionid.id_str,
 252                               sessionid.hostname);
 253
 254         rec->delete_rec(rec);
 255
 256         TALLOC_FREE(rec);
 257 }
 258
 259 /********************************************************************
 260 ********************************************************************/
 261
 262 static bool session_traverse(int (*fn)(struct db_record *db,
 263                                        void *private_data),
 264                              void *private_data)
 265 {
 266         struct db_context *ctx;
 267
 268         if (!(ctx = session_db_ctx())) {
 269                 DEBUG(3, ("No tdb opened\n"));
 270                 return False;
 271         }
 272
 273         ctx->traverse_read(ctx, fn, private_data);
 274         return True;
 275 }
 276
 277 /********************************************************************
 278 ********************************************************************/
 279
 280 struct session_list {
 281         TALLOC_CTX *mem_ctx;
 282         int count;
 283         struct sessionid *sessions;
 284 };
 285
 286 static int gather_sessioninfo(struct db_record *rec, void *state)
 287 {
 288         struct session_list *sesslist = (struct session_list *) state;
 289         const struct sessionid *current =
 290                 (const struct sessionid *) rec->value.dptr;
 291
 292         sesslist->sessions = TALLOC_REALLOC_ARRAY(
 293                 sesslist->mem_ctx, sesslist->sessions, struct sessionid,
 294                 sesslist->count+1);
 295
 296         if (!sesslist->sessions) {
 297                 sesslist->count = 0;
 298                 return -1;
 299         }
 300
 301         memcpy(&sesslist->sessions[sesslist->count], current,
 302                sizeof(struct sessionid));
 303
 304         sesslist->count++;
 305
 306         DEBUG(7,("gather_sessioninfo session from %s@%s\n",
 307                  current->username, current->remote_machine));
 308
 309         return 0;
 310 }
 311
 312 /********************************************************************
 313 ********************************************************************/
 314
 315 int list_sessions(TALLOC_CTX *mem_ctx, struct sessionid **session_list)
 316 {
 317         struct session_list sesslist;
 318
 319         sesslist.mem_ctx = mem_ctx;
 320         sesslist.count = 0;
 321         sesslist.sessions = NULL;
 322
 323         if (!session_traverse(gather_sessioninfo, (void *) &sesslist)) {
 324                 DEBUG(3, ("Session traverse failed\n"));
 325                 SAFE_FREE(sesslist.sessions);
 326                 *session_list = NULL;
 327                 return 0;
 328         }
 329
 330         *session_list = sesslist.sessions;
 331         return sesslist.count;
 332 }