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         char * hostname;
  69         struct db_context *ctx;
  70         struct db_record *rec;
  71         NTSTATUS status;
  72
  73         vuser->session_keystr = NULL;
  74
  75         /* don't register sessions for the guest user - its just too
  76            expensive to go through pam session code for browsing etc */
  77         if (vuser->guest) {
  78                 return True;
  79         }
  80
  81         if (!(ctx = session_db_ctx())) {
  82                 return False;
  83         }
  84
  85         ZERO_STRUCT(sessionid);
  86
  87         data.dptr = NULL;
  88         data.dsize = 0;
  89
  90         if (lp_utmp()) {
  91
  92                 for (i=1;i<MAX_SESSION_ID;i++) {
  93
  94                         /*
  95                          * This is very inefficient and needs fixing -- vl
  96                          */
  97
  98                         struct server_id sess_pid;
  99
 100                         snprintf(keystr, sizeof(keystr), "ID/%d", i);
 101                         key = string_term_tdb_data(keystr);
 102
 103                         rec = ctx->fetch_locked(ctx, NULL, key);
 104
 105                         if (rec == NULL) {
 106                                 DEBUG(1, ("Could not lock \"%s\"\n", keystr));
 107                                 return False;
 108                         }
 109
 110                         if (rec->value.dsize != sizeof(sessionid)) {
 111                                 DEBUG(1, ("Re-using invalid record\n"));
 112                                 break;
 113                         }
 114
 115                         sess_pid = ((struct sessionid *)rec->value.dptr)->pid;
 116
 117                         if (!process_exists(sess_pid)) {
 118                                 DEBUG(5, ("%s has died -- re-using session\n",
 119                                           procid_str_static(&sess_pid)));
 120                                 break;
 121                         }
 122
 123                         TALLOC_FREE(rec);
 124                 }
 125
 126                 if (i == MAX_SESSION_ID) {
 127                         SMB_ASSERT(rec == NULL);
 128                         DEBUG(1,("session_claim: out of session IDs "
 129                                  "(max is %d)\n", MAX_SESSION_ID));
 130                         return False;
 131                 }
 132
 133                 snprintf(sessionid.id_str, sizeof(sessionid.id_str),
 134                          SESSION_UTMP_TEMPLATE, i);
 135         } else
 136         {
 137                 snprintf(keystr, sizeof(keystr), "ID/%s/%u",
 138                          procid_str_static(&pid), vuser->vuid);
 139                 key = string_term_tdb_data(keystr);
 140
 141                 rec = ctx->fetch_locked(ctx, NULL, key);
 142
 143                 if (rec == NULL) {
 144                         DEBUG(1, ("Could not lock \"%s\"\n", keystr));
 145                         return False;
 146                 }
 147
 148                 snprintf(sessionid.id_str, sizeof(sessionid.id_str),
 149                          SESSION_TEMPLATE, (long unsigned int)sys_getpid(),
 150                          vuser->vuid);
 151         }
 152
 153         SMB_ASSERT(rec != NULL);
 154
 155         /* If 'hostname lookup' == yes, then do the DNS lookup.  This is
 156            needed because utmp and PAM both expect DNS names
 157
 158            client_name() handles this case internally.
 159         */
 160
 161         hostname = client_name();
 162         if (strcmp(hostname, "UNKNOWN") == 0) {
 163                 hostname = client_addr();
 164         }
 165
 166         fstrcpy(sessionid.username, vuser->user.unix_name);
 167         fstrcpy(sessionid.hostname, hostname);
 168         sessionid.id_num = i;  /* Only valid for utmp sessions */
 169         sessionid.pid = pid;
 170         sessionid.uid = vuser->uid;
 171         sessionid.gid = vuser->gid;
 172         fstrcpy(sessionid.remote_machine, get_remote_machine_name());
 173         fstrcpy(sessionid.ip_addr_str, client_addr());
 174         sessionid.connect_start = time(NULL);
 175
 176         if (!smb_pam_claim_session(sessionid.username, sessionid.id_str,
 177                                    sessionid.hostname)) {
 178                 DEBUG(1,("pam_session rejected the session for %s [%s]\n",
 179                                 sessionid.username, sessionid.id_str));
 180
 181                 TALLOC_FREE(rec);
 182                 return False;
 183         }
 184
 185         data.dptr = (uint8 *)&sessionid;
 186         data.dsize = sizeof(sessionid);
 187
 188         status = rec->store(rec, data, TDB_REPLACE);
 189
 190         TALLOC_FREE(rec);
 191
 192         if (!NT_STATUS_IS_OK(status)) {
 193                 DEBUG(1,("session_claim: unable to create session id "
 194                          "record: %s\n", nt_errstr(status)));
 195                 return False;
 196         }
 197
 198         if (lp_utmp()) {
 199                 sys_utmp_claim(sessionid.username, sessionid.hostname,
 200                                sessionid.ip_addr_str,
 201                                sessionid.id_str, sessionid.id_num);
 202         }
 203
 204         TALLOC_FREE(rec);
 205
 206         vuser->session_keystr = talloc_strdup(vuser, keystr);
 207         if (!vuser->session_keystr) {
 208                 DEBUG(0, ("session_claim:  talloc_strdup() failed for "
 209                           "session_keystr\n"));
 210                 return False;
 211         }
 212         return True;
 213 }
 214
 215 /********************************************************************
 216  called when a session is destroyed
 217 ********************************************************************/
 218
 219 void session_yield(user_struct *vuser)
 220 {
 221         TDB_DATA key;
 222         struct sessionid sessionid;
 223         struct db_context *ctx;
 224         struct db_record *rec;
 225
 226         if (!(ctx = session_db_ctx())) return;
 227
 228         if (!vuser->session_keystr) {
 229                 return;
 230         }
 231
 232         key = string_term_tdb_data(vuser->session_keystr);
 233
 234         if (!(rec = ctx->fetch_locked(ctx, NULL, key))) {
 235                 return;
 236         }
 237
 238         if (rec->value.dsize != sizeof(sessionid))
 239                 return;
 240
 241         memcpy(&sessionid, rec->value.dptr, sizeof(sessionid));
 242
 243         if (lp_utmp()) {
 244                 sys_utmp_yield(sessionid.username, sessionid.hostname,
 245                                sessionid.ip_addr_str,
 246                                sessionid.id_str, sessionid.id_num);
 247         }
 248
 249         smb_pam_close_session(sessionid.username, sessionid.id_str,
 250                               sessionid.hostname);
 251
 252         rec->delete_rec(rec);
 253
 254         TALLOC_FREE(rec);
 255 }
 256
 257 /********************************************************************
 258 ********************************************************************/
 259
 260 static BOOL session_traverse(int (*fn)(struct db_record *db,
 261                                        void *private_data),
 262                              void *private_data)
 263 {
 264         struct db_context *ctx;
 265
 266         if (!(ctx = session_db_ctx())) {
 267                 DEBUG(3, ("No tdb opened\n"));
 268                 return False;
 269         }
 270
 271         ctx->traverse_read(ctx, fn, private_data);
 272         return True;
 273 }
 274
 275 /********************************************************************
 276 ********************************************************************/
 277
 278 struct session_list {
 279         TALLOC_CTX *mem_ctx;
 280         int count;
 281         struct sessionid *sessions;
 282 };
 283
 284 static int gather_sessioninfo(struct db_record *rec, void *state)
 285 {
 286         struct session_list *sesslist = (struct session_list *) state;
 287         const struct sessionid *current =
 288                 (const struct sessionid *) rec->value.dptr;
 289
 290         sesslist->sessions = TALLOC_REALLOC_ARRAY(
 291                 sesslist->mem_ctx, sesslist->sessions, struct sessionid,
 292                 sesslist->count+1);
 293
 294         if (!sesslist->sessions) {
 295                 sesslist->count = 0;
 296                 return -1;
 297         }
 298
 299         memcpy(&sesslist->sessions[sesslist->count], current,
 300                sizeof(struct sessionid));
 301
 302         sesslist->count++;
 303
 304         DEBUG(7,("gather_sessioninfo session from %s@%s\n",
 305                  current->username, current->remote_machine));
 306
 307         return 0;
 308 }
 309
 310 /********************************************************************
 311 ********************************************************************/
 312
 313 int list_sessions(TALLOC_CTX *mem_ctx, struct sessionid **session_list)
 314 {
 315         struct session_list sesslist;
 316
 317         sesslist.mem_ctx = mem_ctx;
 318         sesslist.count = 0;
 319         sesslist.sessions = NULL;
 320
 321         if (!session_traverse(gather_sessioninfo, (void *) &sesslist)) {
 322                 DEBUG(3, ("Session traverse failed\n"));
 323                 SAFE_FREE(sesslist.sessions);
 324                 *session_list = NULL;
 325                 return 0;
 326         }
 327
 328         *session_list = sesslist.sessions;
 329         return sesslist.count;
 330 }