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[nfs-utils.git] / utils / gssd / gssd_proc.c
1 /*
2   gssd_proc.c
3
4   Copyright (c) 2000-2004 The Regents of the University of Michigan.
5   All rights reserved.
6
7   Copyright (c) 2000 Dug Song <dugsong@UMICH.EDU>.
8   Copyright (c) 2001 Andy Adamson <andros@UMICH.EDU>.
9   Copyright (c) 2002 Marius Aamodt Eriksen <marius@UMICH.EDU>.
10   Copyright (c) 2002 Bruce Fields <bfields@UMICH.EDU>
11   Copyright (c) 2004 Kevin Coffman <kwc@umich.edu>
12   All rights reserved, all wrongs reversed.
13
14   Redistribution and use in source and binary forms, with or without
15   modification, are permitted provided that the following conditions
16   are met:
17
18   1. Redistributions of source code must retain the above copyright
19      notice, this list of conditions and the following disclaimer.
20   2. Redistributions in binary form must reproduce the above copyright
21      notice, this list of conditions and the following disclaimer in the
22      documentation and/or other materials provided with the distribution.
23   3. Neither the name of the University nor the names of its
24      contributors may be used to endorse or promote products derived
25      from this software without specific prior written permission.
26
27   THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
28   WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
29   MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
30   DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31   FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
32   CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
33   SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
34   BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
35   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
36   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
37   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
38
39 */
40
41 #ifndef _GNU_SOURCE
42 #define _GNU_SOURCE
43 #endif
44 #include "config.h"
45 #include <sys/param.h>
46 #include <rpc/rpc.h>
47 #include <sys/stat.h>
48 #include <sys/socket.h>
49 #include <arpa/inet.h>
50
51 #include <stdio.h>
52 #include <stdlib.h>
53 #include <pwd.h>
54 #include <grp.h>
55 #include <string.h>
56 #include <dirent.h>
57 #include <poll.h>
58 #include <fcntl.h>
59 #include <signal.h>
60 #include <unistd.h>
61 #include <errno.h>
62 #include <gssapi/gssapi.h>
63 #include <netdb.h>
64
65 #include "gssd.h"
66 #include "err_util.h"
67 #include "gss_util.h"
68 #include "gss_oids.h"
69 #include "krb5_util.h"
70 #include "context.h"
71
72 /*
73  * pollarray:
74  *      array of struct pollfd suitable to pass to poll. initialized to
75  *      zero - a zero struct is ignored by poll() because the events mask is 0.
76  *
77  * clnt_list:
78  *      linked list of struct clnt_info which associates a clntXXX directory
79  *      with an index into pollarray[], and other basic data about that client.
80  *
81  * Directory structure: created by the kernel nfs client
82  *      /pipefsdir/clntXX             : one per rpc_clnt struct in the kernel
83  *      /pipefsdir/clntXX/krb5        : read uid for which kernel wants
84  *                                       a context, write the resulting context
85  *      /pipefsdir/clntXX/info        : stores info such as server name
86  *
87  * Algorithm:
88  *      Poll all /pipefsdir/clntXX/krb5 files.  When ready, data read
89  *      is a uid; performs rpcsec_gss context initialization protocol to
90  *      get a cred for that user.  Writes result to corresponding krb5 file
91  *      in a form the kernel code will understand.
92  *      In addition, we make sure we are notified whenever anything is
93  *      created or destroyed in pipefsdir/ or in an of the clntXX directories,
94  *      and rescan the whole pipefsdir when this happens.
95  */
96
97 struct pollfd * pollarray;
98
99 int pollsize;  /* the size of pollaray (in pollfd's) */
100
101 /* XXX buffer problems: */
102 static int
103 read_service_info(char *info_file_name, char **servicename, char **servername,
104                   int *prog, int *vers, char **protocol) {
105 #define INFOBUFLEN 256
106         char            buf[INFOBUFLEN];
107         static char     dummy[128];
108         int             nbytes;
109         static char     service[128];
110         static char     address[128];
111         char            program[16];
112         char            version[16];
113         char            protoname[16];
114         in_addr_t       inaddr;
115         int             fd = -1;
116         struct hostent  *ent = NULL;
117         int             numfields;
118
119         *servicename = *servername = *protocol = NULL;
120
121         if ((fd = open(info_file_name, O_RDONLY)) == -1) {
122                 printerr(0, "ERROR: can't open %s: %s\n", info_file_name,
123                          strerror(errno));
124                 goto fail;
125         }
126         if ((nbytes = read(fd, buf, INFOBUFLEN)) == -1)
127                 goto fail;
128         close(fd);
129
130         numfields = sscanf(buf,"RPC server: %s\n"
131                    "service: %s %s version %s\n"
132                    "address: %s\n"
133                    "protocol: %s\n",
134                    dummy,
135                    service, program, version,
136                    address,
137                    protoname);
138
139         if (numfields == 5) {
140                 strcpy(protoname, "tcp");
141         } else if (numfields != 6) {
142                 goto fail;
143         }
144
145         /* check service, program, and version */
146         if(memcmp(service, "nfs", 3)) return -1;
147         *prog = atoi(program + 1); /* skip open paren */
148         *vers = atoi(version);
149         if((*prog != 100003) || ((*vers != 2) && (*vers != 3) && (*vers != 4)))
150                 goto fail;
151
152         /* create service name */
153         inaddr = inet_addr(address);
154         if (!(ent = gethostbyaddr(&inaddr, sizeof(inaddr), AF_INET))) {
155                 printerr(0, "ERROR: can't resolve server %s name\n", address);
156                 goto fail;
157         }
158         if (!(*servername = calloc(strlen(ent->h_name) + 1, 1)))
159                 goto fail;
160         memcpy(*servername, ent->h_name, strlen(ent->h_name));
161         snprintf(buf, INFOBUFLEN, "%s@%s", service, ent->h_name);
162         if (!(*servicename = calloc(strlen(buf) + 1, 1)))
163                 goto fail;
164         memcpy(*servicename, buf, strlen(buf));
165
166         if (!(*protocol = strdup(protoname)))
167                 goto fail;
168         return 0;
169 fail:
170         printerr(0, "ERROR: failed to read service info\n");
171         if (fd != -1) close(fd);
172         if (*servername) free(*servername);
173         if (*servicename) free(*servicename);
174         if (*protocol) free(*protocol);
175         return -1;
176 }
177
178 static void
179 destroy_client(struct clnt_info *clp)
180 {
181         if (clp->dir_fd != -1) close(clp->dir_fd);
182         if (clp->krb5_fd != -1) close(clp->krb5_fd);
183         if (clp->spkm3_fd != -1) close(clp->spkm3_fd);
184         if (clp->dirname) free(clp->dirname);
185         if (clp->servicename) free(clp->servicename);
186         if (clp->servername) free(clp->servername);
187         if (clp->protocol) free(clp->protocol);
188         free(clp);
189 }
190
191 static struct clnt_info *
192 insert_new_clnt(void)
193 {
194         struct clnt_info        *clp = NULL;
195
196         if (!(clp = (struct clnt_info *)calloc(1,sizeof(struct clnt_info)))) {
197                 printerr(0, "ERROR: can't malloc clnt_info: %s\n",
198                          strerror(errno));
199                 goto out;
200         }
201         clp->krb5_poll_index = -1;
202         clp->spkm3_poll_index = -1;
203         clp->krb5_fd = -1;
204         clp->spkm3_fd = -1;
205         clp->dir_fd = -1;
206
207         TAILQ_INSERT_HEAD(&clnt_list, clp, list);
208 out:
209         return clp;
210 }
211
212 static int
213 process_clnt_dir_files(struct clnt_info * clp)
214 {
215         char    kname[32];
216         char    sname[32];
217         char    info_file_name[32];
218
219         snprintf(kname, sizeof(kname), "%s/krb5", clp->dirname);
220         clp->krb5_fd = open(kname, O_RDWR);
221         snprintf(sname, sizeof(sname), "%s/spkm3", clp->dirname);
222         clp->spkm3_fd = open(sname, O_RDWR);
223         if((clp->krb5_fd == -1) && (clp->spkm3_fd == -1))
224                 return -1;
225         snprintf(info_file_name, sizeof(info_file_name), "%s/info",
226                         clp->dirname);
227         if (read_service_info(info_file_name, &clp->servicename,
228                                 &clp->servername, &clp->prog, &clp->vers,
229                                 &clp->protocol))
230                 return -1;
231         return 0;
232 }
233
234 static int
235 get_poll_index(int *ind)
236 {
237         int i;
238
239         *ind = -1;
240         for (i=0; i<FD_ALLOC_BLOCK; i++) {
241                 if (pollarray[i].events == 0) {
242                         *ind = i;
243                         break;
244                 }
245         }
246         if (*ind == -1) {
247                 printerr(0, "ERROR: No pollarray slots open\n");
248                 return -1;
249         }
250         return 0;
251 }
252
253 static void
254 process_clnt_dir(char *dir)
255 {
256         struct clnt_info *      clp;
257
258         if (!(clp = insert_new_clnt()))
259                 goto fail_destroy_client;
260
261         if (!(clp->dirname = calloc(strlen(dir) + 1, 1))) {
262                 goto fail_destroy_client;
263         }
264         memcpy(clp->dirname, dir, strlen(dir));
265         if ((clp->dir_fd = open(clp->dirname, O_RDONLY)) == -1) {
266                 printerr(0, "ERROR: can't open %s: %s\n",
267                          clp->dirname, strerror(errno));
268                 goto fail_destroy_client;
269         }
270         fcntl(clp->dir_fd, F_SETSIG, DNOTIFY_SIGNAL);
271         fcntl(clp->dir_fd, F_NOTIFY, DN_CREATE | DN_DELETE | DN_MULTISHOT);
272
273         if (process_clnt_dir_files(clp))
274                 goto fail_keep_client;
275
276         if(clp->krb5_fd != -1) {
277                 if (get_poll_index(&clp->krb5_poll_index)) {
278                         printerr(0, "ERROR: Too many krb5 clients\n");
279                         goto fail_destroy_client;
280                 }
281                 pollarray[clp->krb5_poll_index].fd = clp->krb5_fd;
282                 pollarray[clp->krb5_poll_index].events |= POLLIN;
283         }
284
285         if(clp->spkm3_fd != -1) {
286                 if (get_poll_index(&clp->spkm3_poll_index)) {
287                         printerr(0, "ERROR: Too many spkm3 clients\n");
288                         goto fail_destroy_client;
289                 }
290                 pollarray[clp->spkm3_poll_index].fd = clp->spkm3_fd;
291                 pollarray[clp->spkm3_poll_index].events |= POLLIN;
292         }
293
294         return;
295
296 fail_destroy_client:
297         if (clp) {
298                 TAILQ_REMOVE(&clnt_list, clp, list);
299                 destroy_client(clp);
300         }
301 fail_keep_client:
302         /* We couldn't find some subdirectories, but we keep the client
303          * around in case we get a notification on the directory when the
304          * subdirectories are created. */
305         return;
306 }
307
308 void
309 init_client_list(void)
310 {
311         TAILQ_INIT(&clnt_list);
312         /* Eventually plan to grow/shrink poll array: */
313         pollsize = FD_ALLOC_BLOCK;
314         pollarray = calloc(pollsize, sizeof(struct pollfd));
315 }
316
317 static void
318 destroy_client_list(void)
319 {
320         struct clnt_info        *clp;
321
322         printerr(1, "processing client list\n");
323
324         while (clnt_list.tqh_first != NULL) {
325                 clp = clnt_list.tqh_first;
326                 TAILQ_REMOVE(&clnt_list, clp, list);
327                 destroy_client(clp);
328         }
329 }
330
331 /* Used to read (and re-read) list of clients, set up poll array. */
332 int
333 update_client_list(void)
334 {
335         struct dirent **namelist;
336         int i,j;
337
338         destroy_client_list();
339
340         if (chdir(pipefsdir) < 0) {
341                 printerr(0, "ERROR: can't chdir to %s: %s\n",
342                          pipefsdir, strerror(errno));
343                 return -1;
344         }
345
346         memset(pollarray, 0, pollsize * sizeof(struct pollfd));
347
348         j = scandir(pipefsdir, &namelist, NULL, alphasort);
349         if (j < 0) {
350                 printerr(0, "ERROR: can't scandir %s: %s\n",
351                          pipefsdir, strerror(errno));
352                 return -1;
353         }
354         for (i=0; i < j; i++) {
355                 if (i < FD_ALLOC_BLOCK
356                                 && !strncmp(namelist[i]->d_name, "clnt", 4))
357                         process_clnt_dir(namelist[i]->d_name);
358                 free(namelist[i]);
359         }
360
361         free(namelist);
362         return 0;
363 }
364
365 static int
366 do_downcall(int k5_fd, uid_t uid, struct authgss_private_data *pd,
367             gss_buffer_desc *context_token)
368 {
369         char    buf[2048];
370         char    *p = buf, *end = buf + 2048;
371         unsigned int timeout = 0; /* XXX decide on a reasonable value */
372
373         printerr(1, "doing downcall\n");
374
375         if (WRITE_BYTES(&p, end, uid)) goto out_err;
376         /* Not setting any timeout for now: */
377         if (WRITE_BYTES(&p, end, timeout)) goto out_err;
378         if (WRITE_BYTES(&p, end, pd->pd_seq_win)) goto out_err;
379         if (write_buffer(&p, end, &pd->pd_ctx_hndl)) goto out_err;
380         if (write_buffer(&p, end, context_token)) goto out_err;
381
382         if (write(k5_fd, buf, p - buf) < p - buf) goto out_err;
383         return 0;
384 out_err:
385         printerr(0, "Failed to write downcall!\n");
386         return -1;
387 }
388
389 static int
390 do_error_downcall(int k5_fd, uid_t uid, int err)
391 {
392         char    buf[1024];
393         char    *p = buf, *end = buf + 1024;
394         unsigned int timeout = 0;
395         int     zero = 0;
396
397         printerr(1, "doing error downcall\n");
398
399         if (WRITE_BYTES(&p, end, uid)) goto out_err;
400         if (WRITE_BYTES(&p, end, timeout)) goto out_err;
401         /* use seq_win = 0 to indicate an error: */
402         if (WRITE_BYTES(&p, end, zero)) goto out_err;
403         if (WRITE_BYTES(&p, end, err)) goto out_err;
404
405         if (write(k5_fd, buf, p - buf) < p - buf) goto out_err;
406         return 0;
407 out_err:
408         printerr(0, "Failed to write error downcall!\n");
409         return -1;
410 }
411
412 /*
413  * Create an RPC connection and establish an authenticated
414  * gss context with a server.
415  */
416 int create_auth_rpc_client(struct clnt_info *clp,
417                            AUTH **auth_return,
418                            uid_t uid,
419                            int authtype)
420 {
421         CLIENT                  *rpc_clnt = NULL;
422         struct rpc_gss_sec      sec;
423         AUTH                    *auth = NULL;
424         uid_t                   save_uid = -1;
425         int                     retval = -1;
426         OM_uint32               min_stat;
427
428         sec.qop = GSS_C_QOP_DEFAULT;
429         sec.svc = RPCSEC_GSS_SVC_NONE;
430         sec.cred = GSS_C_NO_CREDENTIAL;
431         sec.req_flags = 0;
432         if (authtype == AUTHTYPE_KRB5) {
433                 sec.mech = (gss_OID)&krb5oid;
434                 sec.req_flags = GSS_C_MUTUAL_FLAG;
435         }
436         else if (authtype == AUTHTYPE_SPKM3) {
437                 sec.mech = (gss_OID)&spkm3oid;
438                 sec.req_flags = GSS_C_ANON_FLAG;
439         }
440         else {
441                 printerr(0, "ERROR: Invalid authentication type (%d) "
442                         "in create_auth_rpc_client\n", authtype);
443                 goto out_fail;
444         }
445
446
447         if (authtype == AUTHTYPE_KRB5) {
448 #ifdef HAVE_SET_ALLOWABLE_ENCTYPES
449                 /*
450                  * Do this before creating rpc connection since we won't need
451                  * rpc connection if it fails!
452                  */
453                 if (limit_krb5_enctypes(&sec, uid)) {
454                         printerr(1, "WARNING: Failed while limiting krb5 "
455                                     "encryption types for user with uid %d\n",
456                                  uid);
457                         goto out_fail;
458                 }
459 #endif
460         }
461
462         /* Create the context as the user (not as root) */
463         save_uid = geteuid();
464         if (seteuid(uid) != 0) {
465                 printerr(0, "WARNING: Failed to seteuid for "
466                             "user with uid %d\n", uid);
467                 goto out_fail;
468         }
469         printerr(2, "creating context using euid %d (save_uid %d)\n",
470                         geteuid(), save_uid);
471
472         /* create an rpc connection to the nfs server */
473
474         printerr(2, "creating %s client for server %s\n", clp->protocol,
475                         clp->servername);
476         if ((rpc_clnt = clnt_create(clp->servername, clp->prog, clp->vers,
477                                         clp->protocol)) == NULL) {
478                 printerr(0, "WARNING: can't create rpc_clnt for server "
479                             "%s for user with uid %d\n",
480                         clp->servername, uid);
481                 goto out_fail;
482         }
483
484         printerr(2, "creating context with server %s\n", clp->servicename);
485         auth = authgss_create_default(rpc_clnt, clp->servicename, &sec);
486         if (!auth) {
487                 /* Our caller should print appropriate message */
488                 printerr(2, "WARNING: Failed to create krb5 context for "
489                             "user with uid %d for server %s\n",
490                          uid, clp->servername);
491                 goto out_fail;
492         }
493
494         /* Restore euid to original value */
495         if (seteuid(save_uid) != 0) {
496                 printerr(0, "WARNING: Failed to restore euid"
497                             " to uid %d\n", save_uid);
498                 goto out_fail;
499         }
500         save_uid = -1;
501
502         /* Success !!! */
503         *auth_return = auth;
504         retval = 0;
505
506   out_fail:
507         if (sec.cred != GSS_C_NO_CREDENTIAL)
508                 gss_release_cred(&min_stat, &sec.cred);
509         if (rpc_clnt) clnt_destroy(rpc_clnt);
510
511         return retval;
512 }
513
514
515 /*
516  * this code uses the userland rpcsec gss library to create a krb5
517  * context on behalf of the kernel
518  */
519 void
520 handle_krb5_upcall(struct clnt_info *clp)
521 {
522         uid_t                   uid;
523         AUTH                    *auth;
524         struct authgss_private_data pd;
525         gss_buffer_desc         token;
526         char                    **credlist = NULL;
527         char                    **ccname;
528
529         printerr(1, "handling krb5 upcall\n");
530
531         token.length = 0;
532         token.value = NULL;
533
534         if (read(clp->krb5_fd, &uid, sizeof(uid)) < sizeof(uid)) {
535                 printerr(0, "WARNING: failed reading uid from krb5 "
536                             "upcall pipe: %s\n", strerror(errno));
537                 goto out;
538         }
539
540         if (uid == 0) {
541                 int success = 0;
542
543                 /*
544                  * Get a list of credential cache names and try each
545                  * of them until one works or we've tried them all
546                  */
547                 if (gssd_get_krb5_machine_cred_list(&credlist)) {
548                         printerr(0, "WARNING: Failed to obtain machine "
549                                     "credentials for connection to "
550                                     "server %s\n", clp->servername);
551                                 goto out_return_error;
552                 }
553                 for (ccname = credlist; ccname && *ccname; ccname++) {
554                         gssd_setup_krb5_machine_gss_ccache(*ccname);
555                         if ((create_auth_rpc_client(clp, &auth, uid,
556                                                     AUTHTYPE_KRB5)) == 0) {
557                                 /* Success! */
558                                 success++;
559                                 break;
560                         }
561                         printerr(2, "WARNING: Failed to create krb5 context "
562                                     "for user with uid %d with credentials "
563                                     "cache %s for server %s\n",
564                                  uid, *ccname, clp->servername);
565                 }
566                 gssd_free_krb5_machine_cred_list(credlist);
567                 if (!success) {
568                         printerr(0, "WARNING: Failed to create krb5 context "
569                                     "for user with uid %d with any "
570                                     "credentials cache for server %s\n",
571                                  uid, clp->servername);
572                         goto out_return_error;
573                 }
574         }
575         else {
576                 /* Tell krb5 gss which credentials cache to use */
577                 gssd_setup_krb5_user_gss_ccache(uid, clp->servername);
578
579                 if (create_auth_rpc_client(clp, &auth, uid, AUTHTYPE_KRB5)) {
580                         printerr(0, "WARNING: Failed to create krb5 context "
581                                     "for user with uid %d for server %s\n",
582                                  uid, clp->servername);
583                         goto out_return_error;
584                 }
585         }
586
587         if (!authgss_get_private_data(auth, &pd)) {
588                 printerr(0, "WARNING: Failed to obtain authentication "
589                             "data for user with uid %d for server %s\n",
590                          uid, clp->servername);
591                 goto out_return_error;
592         }
593
594         if (serialize_context_for_kernel(pd.pd_ctx, &token)) {
595                 printerr(0, "WARNING: Failed to serialize krb5 context for "
596                             "user with uid %d for server %s\n",
597                          uid, clp->servername);
598                 goto out_return_error;
599         }
600
601         do_downcall(clp->krb5_fd, uid, &pd, &token);
602
603         if (token.value)
604                 free(token.value);
605 out:
606         return;
607
608 out_return_error:
609         do_error_downcall(clp->krb5_fd, uid, -1);
610         return;
611 }
612
613 /*
614  * this code uses the userland rpcsec gss library to create an spkm3
615  * context on behalf of the kernel
616  */
617 void
618 handle_spkm3_upcall(struct clnt_info *clp)
619 {
620         uid_t                   uid;
621         AUTH                    *auth;
622         struct authgss_private_data pd;
623         gss_buffer_desc         token;
624
625         printerr(2, "handling spkm3 upcall\n");
626
627         token.length = 0;
628         token.value = NULL;
629
630         if (read(clp->spkm3_fd, &uid, sizeof(uid)) < sizeof(uid)) {
631                 printerr(0, "WARNING: failed reading uid from spkm3 "
632                          "upcall pipe: %s\n", strerror(errno));
633                 goto out;
634         }
635
636         if (create_auth_rpc_client(clp, &auth, uid, AUTHTYPE_SPKM3)) {
637                 printerr(0, "WARNING: Failed to create spkm3 context for "
638                             "user with uid %d\n", uid);
639                 goto out_return_error;
640         }
641
642         if (!authgss_get_private_data(auth, &pd)) {
643                 printerr(0, "WARNING: Failed to obtain authentication "
644                             "data for user with uid %d for server %s\n",
645                          uid, clp->servername);
646                 goto out_return_error;
647         }
648
649         if (serialize_context_for_kernel(pd.pd_ctx, &token)) {
650                 printerr(0, "WARNING: Failed to serialize spkm3 context for "
651                             "user with uid %d for server\n",
652                          uid, clp->servername);
653                 goto out_return_error;
654         }
655
656         do_downcall(clp->spkm3_fd, uid, &pd, &token);
657
658         if (token.value)
659                 free(token.value);
660 out:
661         return;
662
663 out_return_error:
664         do_error_downcall(clp->spkm3_fd, uid, -1);
665         return;
666 }