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                         sess_pid = ((struct sessionid *)rec->value.dptr)->pid;
 117
 118                         if (!process_exists(sess_pid)) {
 119                                 DEBUG(5, ("%s has died -- re-using session\n",
 120                                           procid_str_static(&sess_pid)));
 121                                 break;
 122                         }
 123
 124                         TALLOC_FREE(rec);
 125                 }
 126
 127                 if (i == MAX_SESSION_ID) {
 128                         SMB_ASSERT(rec == NULL);
 129                         DEBUG(1,("session_claim: out of session IDs "
 130                                  "(max is %d)\n", MAX_SESSION_ID));
 131                         return False;
 132                 }
 133
 134                 snprintf(sessionid.id_str, sizeof(sessionid.id_str),
 135                          SESSION_UTMP_TEMPLATE, i);
 136         } else
 137         {
 138                 snprintf(keystr, sizeof(keystr), "ID/%s/%u",
 139                          procid_str_static(&pid), vuser->vuid);
 140                 key = string_term_tdb_data(keystr);
 141
 142                 rec = ctx->fetch_locked(ctx, NULL, key);
 143
 144                 if (rec == NULL) {
 145                         DEBUG(1, ("Could not lock \"%s\"\n", keystr));
 146                         return False;
 147                 }
 148
 149                 snprintf(sessionid.id_str, sizeof(sessionid.id_str),
 150                          SESSION_TEMPLATE, (long unsigned int)sys_getpid(),
 151                          vuser->vuid);
 152         }
 153
 154         SMB_ASSERT(rec != NULL);
 155
 156         /* If 'hostname lookup' == yes, then do the DNS lookup.  This is
 157            needed because utmp and PAM both expect DNS names
 158
 159            client_name() handles this case internally.
 160         */
 161
 162         hostname = client_name(get_client_fd());
 163         if (strcmp(hostname, "UNKNOWN") == 0) {
 164                 hostname = client_addr(get_client_fd(),addr,sizeof(addr));
 165         }
 166
 167         fstrcpy(sessionid.username, vuser->server_info->unix_name);
 168         fstrcpy(sessionid.hostname, hostname);
 169         sessionid.id_num = i;  /* Only valid for utmp sessions */
 170         sessionid.pid = pid;
 171         sessionid.uid = vuser->server_info->utok.uid;
 172         sessionid.gid = vuser->server_info->utok.gid;
 173         fstrcpy(sessionid.remote_machine, get_remote_machine_name());
 174         fstrcpy(sessionid.ip_addr_str,
 175                 client_addr(get_client_fd(),addr,sizeof(addr)));
 176         sessionid.connect_start = time(NULL);
 177
 178         if (!smb_pam_claim_session(sessionid.username, sessionid.id_str,
 179                                    sessionid.hostname)) {
 180                 DEBUG(1,("pam_session rejected the session for %s [%s]\n",
 181                                 sessionid.username, sessionid.id_str));
 182
 183                 TALLOC_FREE(rec);
 184                 return False;
 185         }
 186
 187         data.dptr = (uint8 *)&sessionid;
 188         data.dsize = sizeof(sessionid);
 189
 190         status = rec->store(rec, data, TDB_REPLACE);
 191
 192         TALLOC_FREE(rec);
 193
 194         if (!NT_STATUS_IS_OK(status)) {
 195                 DEBUG(1,("session_claim: unable to create session id "
 196                          "record: %s\n", nt_errstr(status)));
 197                 return False;
 198         }
 199
 200         if (lp_utmp()) {
 201                 sys_utmp_claim(sessionid.username, sessionid.hostname,
 202                                sessionid.ip_addr_str,
 203                                sessionid.id_str, sessionid.id_num);
 204         }
 205
 206         vuser->session_keystr = talloc_strdup(vuser, keystr);
 207         if (!vuser->session_keystr) {
 208                 DEBUG(0, ("session_claim:  talloc_strdup() failed for session_keystr\n"));
 209                 return False;
 210         }
 211         return True;
 212 }
 213
 214 /********************************************************************
 215  called when a session is destroyed
 216 ********************************************************************/
 217
 218 void session_yield(user_struct *vuser)
 219 {
 220         TDB_DATA key;
 221         struct sessionid sessionid;
 222         struct db_context *ctx;
 223         struct db_record *rec;
 224
 225         if (!(ctx = session_db_ctx())) return;
 226
 227         if (!vuser->session_keystr) {
 228                 return;
 229         }
 230
 231         key = string_term_tdb_data(vuser->session_keystr);
 232
 233         if (!(rec = ctx->fetch_locked(ctx, NULL, key))) {
 234                 return;
 235         }
 236
 237         if (rec->value.dsize != sizeof(sessionid))
 238                 return;
 239
 240         memcpy(&sessionid, rec->value.dptr, sizeof(sessionid));
 241
 242         if (lp_utmp()) {
 243                 sys_utmp_yield(sessionid.username, sessionid.hostname,
 244                                sessionid.ip_addr_str,
 245                                sessionid.id_str, sessionid.id_num);
 246         }
 247
 248         smb_pam_close_session(sessionid.username, sessionid.id_str,
 249                               sessionid.hostname);
 250
 251         rec->delete_rec(rec);
 252
 253         TALLOC_FREE(rec);
 254 }
 255
 256 /********************************************************************
 257 ********************************************************************/
 258
 259 static bool session_traverse(int (*fn)(struct db_record *db,
 260                                        void *private_data),
 261                              void *private_data)
 262 {
 263         struct db_context *ctx;
 264
 265         if (!(ctx = session_db_ctx())) {
 266                 DEBUG(3, ("No tdb opened\n"));
 267                 return False;
 268         }
 269
 270         ctx->traverse_read(ctx, fn, private_data);
 271         return True;
 272 }
 273
 274 /********************************************************************
 275 ********************************************************************/
 276
 277 struct session_list {
 278         TALLOC_CTX *mem_ctx;
 279         int count;
 280         struct sessionid *sessions;
 281 };
 282
 283 static int gather_sessioninfo(struct db_record *rec, void *state)
 284 {
 285         struct session_list *sesslist = (struct session_list *) state;
 286         const struct sessionid *current =
 287                 (const struct sessionid *) rec->value.dptr;
 288
 289         sesslist->sessions = TALLOC_REALLOC_ARRAY(
 290                 sesslist->mem_ctx, sesslist->sessions, struct sessionid,
 291                 sesslist->count+1);
 292
 293         if (!sesslist->sessions) {
 294                 sesslist->count = 0;
 295                 return -1;
 296         }
 297
 298         memcpy(&sesslist->sessions[sesslist->count], current,
 299                sizeof(struct sessionid));
 300
 301         sesslist->count++;
 302
 303         DEBUG(7,("gather_sessioninfo session from %s@%s\n",
 304                  current->username, current->remote_machine));
 305
 306         return 0;
 307 }
 308
 309 /********************************************************************
 310 ********************************************************************/
 311
 312 int list_sessions(TALLOC_CTX *mem_ctx, struct sessionid **session_list)
 313 {
 314         struct session_list sesslist;
 315
 316         sesslist.mem_ctx = mem_ctx;
 317         sesslist.count = 0;
 318         sesslist.sessions = NULL;
 319
 320         if (!session_traverse(gather_sessioninfo, (void *) &sesslist)) {
 321                 DEBUG(3, ("Session traverse failed\n"));
 322                 SAFE_FREE(sesslist.sessions);
 323                 *session_list = NULL;
 324                 return 0;
 325         }
 326
 327         *session_list = sesslist.sessions;
 328         return sesslist.count;
 329 }