v1.05: fail-fast if network is likely to be down
[hcoop/debian/libnss-afs.git] / nss_afs.c
1
2 /*****************************************************************************
3 * libnss-afs (nss_afs.c)
4 *
5 * Copyright 2008, licensed under GNU Library General Public License (LGPL)
6 * see COPYING file for details
7 *
8 * by Adam Megacz <megacz@hcoop.net>
9 * derived from Frank Burkhardt's libnss_ptdb,
10 * which was derived from Todd M. Lewis' libnss_pts
11 *****************************************************************************/
12
13 /*
14 * If you are reading this code for the first time, read the rest of
15 * this comment block, then start at the bottom of the file and work
16 * your way upwards.
17 *
18 * All functions which return an int use zero to signal success --
19 * except cpstr(), which returns zero on *failure*. This should be
20 * fixed.
21 *
22 * A note about memory allocation:
23 *
24 * NSS plugins generally ought to work without attempting to call
25 * malloc() (which may fail). Therefore, glibc allocates a buffer
26 * before calling NSS library functions, and passes that buffer to
27 * the NSS library; library functions store their results in the
28 * buffer and return pointers into that buffer.
29 *
30 * The convention used throughout this library is to pass around a
31 * char** which points to a pointer to the first unused byte in the
32 * provided buffer, and a size_t* which points to an int indicating
33 * how many bytes are left between the char** and the end of the
34 * available region.
35 */
36
37 #include <ctype.h>
38 #include <err.h>
39 #include <errno.h>
40 #include <fcntl.h>
41 #include <getopt.h>
42 #include <grp.h>
43 #include <netinet/in.h>
44 #include <nss.h>
45 #include <pthread.h>
46 #include <pwd.h>
47 #include <rx/rx.h>
48 #include <rx/xdr.h>
49 #include <signal.h>
50 #include <stdio.h>
51 #include <stdlib.h>
52 #include <string.h>
53 #include <sys/select.h>
54 #include <sys/socket.h>
55 #include <sys/stat.h>
56 #include <sys/time.h>
57 #include <sys/types.h>
58 #include <unistd.h>
59 #include <afs/afs.h>
60 #include <afs/afsutil.h>
61 #include <afs/cellconfig.h>
62 #include <afs/com_err.h>
63 #include <afs/param.h>
64 #include <afs/ptclient.h>
65 #include <afs/pterror.h>
66 #include <afs/stds.h>
67
68 #define HOMEDIR_AUTO 0
69 #define HOMEDIR_ADMINLINK 1
70 #define HOMEDIR_PREFIX 2
71 #define SHELL_BASH 0
72 #define SHELL_ADMINLINK 1
73 #define SHELL_USERLINK 2
74
75 #define AFS_MAGIC_ANONYMOUS_USERID 32766
76 #define MIN_PAG_GID 0x41000000L
77 #define MAX_PAG_GID 0x41FFFFFFL
78 #define MIN_OLDPAG_GID 0x3f00
79 #define MAX_OLDPAG_GID 0xff00
80
81 #define MAXCELLNAMELEN 256
82 #define MAXUSERNAMELEN 256
83
84 static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
85
86 extern struct ubik_client *pruclient;
87
88 int afs_initialized = 0;
89 char cellname[MAXCELLNAMELEN];
90 char homedir_prefix[MAXPATHLEN];
91 char cell_root[MAXPATHLEN];
92 int homedir_prefix_len=0;
93 char homedirs_method=0;
94 char shells_method=0;
95
96 /**
97 * The cpstr() function copies a null-terminated string from str*
98 * (the first argument) into buf and updates both buf and buflen. If
99 * the string would overflow the buffer, no action is taken. The
100 * number of bytes copied is returned (zero indicates failure).
101 */
102 int cpstr( char *str, char **buf, size_t *buflen) {
103 int len = strlen(str);
104 if ( len >= *buflen-1 ) return 0;
105 strcpy(*buf,str);
106 *buflen -= len + 1;
107 *buf += len + 1;
108 return len;
109 }
110
111 /**
112 * Look up the name corresponding to uid, store in buffer.
113 */
114 enum nss_status ptsid2name(int uid, char **buffer, int *buflen) {
115 int ret, i;
116 idlist lid;
117 namelist lnames;
118
119 init_afs();
120
121 if (uid==AFS_MAGIC_ANONYMOUS_USERID) {
122 if (!cpstr("anonymous", buffer, buflen)) return NSS_STATUS_UNAVAIL;
123 return NSS_STATUS_SUCCESS;
124 }
125
126 if (pthread_mutex_lock(&mutex)) return NSS_STATUS_UNAVAIL;
127
128 lid.idlist_val = (afs_int32*)&uid;
129 lid.idlist_len = 1;
130 lnames.namelist_val = 0;
131 lnames.namelist_len = 0;
132
133 if (ubik_Call(PR_IDToName,pruclient,0,&lid,&lnames) != PRSUCCESS) {
134 pthread_mutex_unlock(&mutex);
135 return NSS_STATUS_UNAVAIL;
136 }
137
138 ret = NSS_STATUS_NOTFOUND;
139 for (i=0;i<lnames.namelist_len;i++) {
140 int delta = strlen(lnames.namelist_val[i]);
141 if ( (delta < buflen) && islower(*(lnames.namelist_val[i])) ) {
142 cpstr(lnames.namelist_val[i], buffer, buflen);
143 ret = NSS_STATUS_SUCCESS;
144 }
145 }
146 free(lnames.namelist_val);
147 /* free(lid.idlist_val); */
148 lid.idlist_val = 0;
149 lid.idlist_len = 0;
150
151 pthread_mutex_unlock(&mutex);
152 return ret;
153 }
154
155 /**
156 * Look up the uid corresponding to name in ptserver.
157 */
158 enum nss_status ptsname2id(char *name, uid_t* uid) {
159 int res;
160 idlist lid;
161 namelist lnames;
162 char uname[MAXUSERNAMELEN];
163
164 init_afs();
165
166 if (!strcmp(name,"anonymous")) {
167 *uid = AFS_MAGIC_ANONYMOUS_USERID;
168 return NSS_STATUS_SUCCESS;
169 }
170
171 if (pthread_mutex_lock(&mutex)) return NSS_STATUS_UNAVAIL;
172
173 lid.idlist_val = 0;
174 lid.idlist_len = 0;
175 lnames.namelist_val = (prname*)uname;
176 // apparently ubik expects to be able to modify this?
177 strncpy(uname, name, MAXUSERNAMELEN);
178 lnames.namelist_len = 1;
179
180 if (ubik_Call(PR_NameToID,pruclient,0,&lnames,&lid) != PRSUCCESS) {
181 pthread_mutex_unlock(&mutex);
182 return NSS_STATUS_UNAVAIL;
183 }
184 pthread_mutex_unlock(&mutex);
185
186 res = (uid_t)lid.idlist_val[0];
187 if (res == AFS_MAGIC_ANONYMOUS_USERID) return NSS_STATUS_NOTFOUND;
188 *uid = res;
189 return NSS_STATUS_SUCCESS;
190 }
191
192 /**
193 * Initialize the library; returns zero on success
194 */
195 int init_afs() {
196 FILE *thiscell;
197 int len;
198 struct stat statbuf;
199
200 if (afs_initialized) {
201 /* wait until /afs/@cell/ appears as a proxy for "the network is up" */
202 if (stat(cell_root, &statbuf)) return -1;
203 return 0;
204 }
205
206 if (pthread_mutex_lock(&mutex)) return -1;
207 do {
208 homedirs_method=HOMEDIR_PREFIX;
209 shells_method=SHELL_USERLINK;
210
211 len = snprintf(cellname, MAXCELLNAMELEN,
212 "%s/ThisCell", AFSDIR_CLIENT_ETC_DIRPATH);
213 if (len < 0 || len >= MAXCELLNAMELEN) return -1;
214
215 thiscell=fopen(cellname,"r");
216 if (thiscell == NULL) break;
217 len=fread(cellname,1,MAXCELLNAMELEN,thiscell);
218 if (!feof(thiscell)) {
219 // Cellname too long
220 fclose(thiscell);
221 strcpy(homedir_prefix,"/tmp/\0");
222 homedir_prefix_len=5;
223 break;
224 }
225 fclose(thiscell);
226
227 if (cellname[len-1] == '\n') len--;
228 cellname[len]='\0';
229
230 /* wait until /afs/@cell/ appears as a proxy for "the network is up" */
231 sprintf(cell_root,"/afs/%s/",cellname);
232 if (stat(cell_root, &statbuf)) break;
233
234 sprintf(homedir_prefix,"/afs/%s/user/",cellname);
235 homedir_prefix_len=strlen(homedir_prefix);
236
237 /* time out requests after 5 seconds to avoid hanging things */
238 rx_SetRxDeadTime(5);
239
240 if (pr_Initialize(0L,AFSDIR_CLIENT_ETC_DIRPATH, 0)) break;
241
242 afs_initialized = 1;
243 pthread_mutex_unlock(&mutex);
244 return 0;
245
246 } while(0);
247 pthread_mutex_unlock(&mutex);
248 return -1;
249 }
250
251
252 /**
253 * Retrieves the homedir for a given user; returns 0 on success.
254 */
255 int get_homedir(char *name, char **buffer, size_t *buflen) {
256 char buf[256];
257 int temp;
258 char *b;
259 b=*buffer;
260 switch (homedirs_method) {
261 case HOMEDIR_PREFIX:
262 homedir_prefix[homedir_prefix_len+0]=name[0];
263 homedir_prefix[homedir_prefix_len+1]='/';
264 homedir_prefix[homedir_prefix_len+2]=name[0];
265 homedir_prefix[homedir_prefix_len+3]=name[1];
266 homedir_prefix[homedir_prefix_len+4]='/';
267 homedir_prefix[homedir_prefix_len+5]=0;
268 strncpy(&homedir_prefix[homedir_prefix_len+5],name,40);
269 if (! cpstr(homedir_prefix,buffer,buflen) ) return -1;
270 break;
271 case HOMEDIR_AUTO:
272 homedir_prefix[homedir_prefix_len]=0;
273 strncpy(&homedir_prefix[homedir_prefix_len],name,40);
274 if (! cpstr(homedir_prefix,buffer,buflen) ) return -1;
275 break;
276 case HOMEDIR_ADMINLINK:
277 if ( snprintf(buf,256,"/afs/%s/admin/homedirs/%s",cellname,name) > 0 ) {
278 temp=readlink(buf,*buffer,*buflen);
279 if ( temp > -1) {
280 b[temp]=0;
281 *buflen = *buflen - temp - 1;
282 return -1;
283 }
284 }
285 if (! cpstr("/tmp",buffer,buflen) ) return -1;
286 break;
287 }
288 return 0;
289 }
290
291 /**
292 * Retrieves the shell for a given user; returns 0 on success.
293 */
294 int get_shell(char *name, char **buffer, size_t *buflen) {
295 char buf[256];
296 int temp;
297 char *b;
298 char* bufx = buf;
299 int bufxlen = 256;
300 b=*buffer;
301
302 switch (shells_method) {
303 case SHELL_BASH:
304 break;
305
306 case SHELL_ADMINLINK:
307 if (snprintf(buf,256,"/afs/%s/admin/shells/%s",cellname,name)<=0) break;
308 temp = readlink(buf,*buffer,*buflen);
309 if (temp < 0) break;
310 b[temp]=0;
311 *buflen = *buflen - temp - 1;
312 return 0;
313
314 case SHELL_USERLINK:
315 if (get_homedir(name, &bufx, &bufxlen)) break;
316 if (strncpy(buf+strlen(buf),"/.loginshell",bufxlen)<=0) break;
317 temp = readlink(buf,*buffer,*buflen);
318 if (temp < 0) break;
319 b[temp]=0;
320 *buflen = *buflen - temp - 1;
321 return 0;
322 }
323 if (! cpstr("/bin/bash",buffer,buflen) )
324 return -1;
325 return 0;
326 }
327
328
329 /*
330 * This function is exported; glibc will invoke it in order to find
331 * the name and list of members of a group specified by a numerical
332 * groupid.
333 */
334 enum nss_status _nss_afs_getgrgid_r (gid_t gid,
335 struct group *result,
336 char *buffer,
337 size_t buflen,
338 int *errnop) {
339 int length;
340 int showgid = 0;
341 if (gid >= MIN_PAG_GID && gid <= MAX_PAG_GID) {
342 showgid = gid-MIN_PAG_GID;
343 } else if (gid >= MIN_OLDPAG_GID && gid <= MAX_OLDPAG_GID) {
344 showgid = gid-MIN_OLDPAG_GID;
345 } else {
346 *errnop=ENOENT;
347 return NSS_STATUS_NOTFOUND;
348 }
349 do {
350 result->gr_gid=gid;
351
352 result->gr_name=buffer;
353 length=snprintf(buffer,buflen,"AfsPag-%x",showgid);
354
355 if (length < 0) break;
356 length += 1;
357 buflen -= length;
358 buffer += length;
359
360 result->gr_passwd=buffer;
361
362 if (!cpstr("x",&buffer,&buflen)) break;
363
364 if (buflen < sizeof(char*)) break;
365 result->gr_mem=buffer;
366 result->gr_mem[0] = NULL;
367
368 *errnop=errno;
369 return NSS_STATUS_SUCCESS;
370
371 } while(0);
372 *errnop=ENOENT;
373 return NSS_STATUS_UNAVAIL;
374 }
375
376 /**
377 * A helper function to fill in the fields of "struct passwd"; used by
378 * both _nss_afs_getpwuid_r() and _nss_afs_getpwnam_r().
379 */
380 enum nss_status fill_result_buf(uid_t uid,
381 char* name,
382 struct passwd *result_buf,
383 char *buffer,
384 size_t buflen,
385 int *errnop) {
386 result_buf->pw_name = name;
387 do {
388 /* set the password to "x" */
389 result_buf->pw_passwd = buffer;
390 if ( ! cpstr("x",&buffer, &buflen) ) break;
391
392 /* the uid and gid are both the uid passed in */
393 result_buf->pw_uid = uid;
394 result_buf->pw_gid = 65534;
395
396 /* make the gecos the same as the PTS name */
397 result_buf->pw_gecos = buffer;
398 if ( ! cpstr(result_buf->pw_name, &buffer, &buflen ) ) break;
399
400 // Set the homedirectory
401 result_buf->pw_dir = buffer;
402 if ( get_homedir(result_buf->pw_name,&buffer,&buflen) ) break;
403
404 // Set the login shell
405 result_buf->pw_shell = buffer;
406 if ( get_shell(result_buf->pw_name,&buffer,&buflen) ) break;
407
408 *errnop = errno;
409 return NSS_STATUS_SUCCESS;
410 } while(0);
411
412 *errnop = ERANGE;
413 return NSS_STATUS_UNAVAIL;
414 }
415
416
417 /**
418 * This function is exported; glibc will invoke it in order to gather
419 * the user information (userid, homedir, shell) associated with a
420 * numerical userid.
421 */
422 enum nss_status _nss_afs_getpwuid_r (uid_t uid,
423 struct passwd *result_buf,
424 char *buffer,
425 size_t buflen,
426 int *errnop) {
427 int temp;
428 char* name;
429
430 if (init_afs()) return NSS_STATUS_UNAVAIL;
431
432 name = buffer;
433 temp = ptsid2name( uid, &buffer, &buflen);
434 if (temp != NSS_STATUS_SUCCESS) {
435 *errnop = ENOENT;
436 return temp;
437 }
438
439 #ifdef LIMIT_USERNAME_CHARS
440 if ( strlen(result_buf->pw_name) > LIMIT_USERNAME_CHARS ) {
441 result_buf->pw_name[LIMIT_USERNAME_CHARS] = '\0';
442 buflen = buflen + ( buffer - &result_buf->pw_name[LIMIT_USERNAME_CHARS+1] );
443 buffer = &result_buf->pw_name[LIMIT_USERNAME_CHARS+1];
444 }
445 #endif
446
447 return fill_result_buf(uid, name, result_buf, buffer, buflen, errnop);
448 }
449
450 /**
451 * This function is exported; glibc will invoke it in order to gather
452 * the user information (userid, homedir, shell) associated with a
453 * username.
454 */
455 enum nss_status _nss_afs_getpwnam_r (char *name,
456 struct passwd *result_buf,
457 char *buffer,
458 size_t buflen,
459 int *errnop) {
460 uid_t uid;
461 int temp;
462
463 if (init_afs()) return NSS_STATUS_UNAVAIL;
464
465 temp = ptsname2id(name,&uid);
466 if (temp != NSS_STATUS_SUCCESS) {
467 *errnop = ENOENT;
468 return temp;
469 }
470
471 return fill_result_buf(uid, name, result_buf, buffer, buflen, errnop);
472 }
473