Fix potential memory leaks found by the Clang static analyzer.
[tinc] / src / fsck.c
1 /*
2     fsck.c -- Check the configuration files for problems
3     Copyright (C) 2014 Guus Sliepen <guus@tinc-vpn.org>
4
5     This program is free software; you can redistribute it and/or modify
6     it under the terms of the GNU General Public License as published by
7     the Free Software Foundation; either version 2 of the License, or
8     (at your option) any later version.
9
10     This program is distributed in the hope that it will be useful,
11     but WITHOUT ANY WARRANTY; without even the implied warranty of
12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13     GNU General Public License for more details.
14
15     You should have received a copy of the GNU General Public License along
16     with this program; if not, write to the Free Software Foundation, Inc.,
17     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
18 */
19
20 #include "system.h"
21
22 #include "crypto.h"
23 #include "ecdsa.h"
24 #include "ecdsagen.h"
25 #include "fsck.h"
26 #include "names.h"
27 #ifndef DISABLE_LEGACY
28 #include "rsa.h"
29 #include "rsagen.h"
30 #endif
31 #include "tincctl.h"
32 #include "utils.h"
33
34 static bool ask_fix(void) {
35         if(force)
36                 return true;
37         if(!tty)
38                 return false;
39 again:
40         fprintf(stderr, "Fix y/n? ");
41         char buf[1024];
42         if(!fgets(buf, sizeof buf, stdin)) {
43                 tty = false;
44                 return false;
45         }
46         if(buf[0] == 'y' || buf[0] == 'Y')
47                 return true;
48         if(buf[0] == 'n' || buf[0] == 'N')
49                 return false;
50         goto again;
51 }
52
53 static void print_tinc_cmd(const char *argv0, const char *format, ...) {
54         if(confbasegiven)
55                 fprintf(stderr, "%s -c %s ", argv0, confbase);
56         else if(netname)
57                 fprintf(stderr, "%s -n %s ", argv0, netname);
58         else
59                 fprintf(stderr, "%s ", argv0);
60         va_list va;
61         va_start(va, format);
62         vfprintf(stderr, format, va);
63         va_end(va);
64         fputc('\n', stderr);
65 }
66
67 static int strtailcmp(const char *str, const char *tail) {
68         size_t slen = strlen(str);
69         size_t tlen = strlen(tail);
70         if(tlen > slen)
71                 return -1;
72         return memcmp(str + slen - tlen, tail, tlen);
73 }
74
75 static void check_conffile(const char *fname, bool server) {
76         FILE *f = fopen(fname, "r");
77         if(!f) {
78                 fprintf(stderr, "ERROR: cannot read %s: %s\n", fname, strerror(errno));
79                 return;
80         }
81
82         char line[2048];
83         int lineno = 0;
84         bool skip = false;
85         const int maxvariables = 50;
86         int count[maxvariables];
87         memset(count, 0, sizeof count);
88
89         while(fgets(line, sizeof line, f)) {
90                 if(skip) {
91                         if(!strncmp(line, "-----END", 8))
92                                 skip = false;
93                         continue;
94                 } else {
95                         if(!strncmp(line, "-----BEGIN", 10)) {
96                                 skip = true;
97                                 continue;
98                         }
99                 }
100
101                 int len;
102                 char *variable, *value, *eol;
103                 variable = value = line;
104
105                 lineno++;
106
107                 eol = line + strlen(line);
108                 while(strchr("\t \r\n", *--eol))
109                         *eol = '\0';
110
111                 if(!line[0] || line[0] == '#')
112                         continue;
113
114                 len = strcspn(value, "\t =");
115                 value += len;
116                 value += strspn(value, "\t ");
117                 if(*value == '=') {
118                         value++;
119                         value += strspn(value, "\t ");
120                 }
121                 variable[len] = '\0';
122
123                 bool found = false;
124
125                 for(int i = 0; variables[i].name; i++) {
126                         if(strcasecmp(variables[i].name, variable))
127                                 continue;
128
129                         found = true;
130
131                         if(variables[i].type & VAR_OBSOLETE) {
132                                 fprintf(stderr, "WARNING: obsolete variable %s in %s line %d\n", variable, fname, lineno);
133                         }
134
135                         if(i < maxvariables)
136                                 count[i]++;
137                 }
138
139                 if(!found)
140                         fprintf(stderr, "WARNING: unknown variable %s in %s line %d\n", variable, fname, lineno);
141
142                 if(!*value)
143                         fprintf(stderr, "ERROR: no value for variable %s in %s line %d\n", variable, fname, lineno);
144         }
145
146         for(int i = 0; variables[i].name && i < maxvariables; i++) {
147                 if(count[i] > 1 && !(variables[i].type & VAR_MULTIPLE))
148                         fprintf(stderr, "WARNING: multiple instances of variable %s in %s\n", variables[i].name, fname);
149         }
150
151         if(ferror(f))
152                 fprintf(stderr, "ERROR: while reading %s: %s\n", fname, strerror(errno));
153
154         fclose(f);
155 }
156
157 int fsck(const char *argv0) {
158 #ifdef HAVE_MINGW
159         int uid = 0;
160 #else
161         uid_t uid = getuid();
162 #endif
163
164         // Check that tinc.conf is readable.
165
166         if(access(tinc_conf, R_OK)) {
167                 fprintf(stderr, "ERROR: cannot read %s: %s\n", tinc_conf, strerror(errno));
168                 if(errno == ENOENT) {
169                         fprintf(stderr, "No tinc configuration found. Create a new one with:\n\n");
170                         print_tinc_cmd(argv0, "init");
171                 } else if(errno == EACCES) {
172                         if(uid != 0)
173                                 fprintf(stderr, "You are currently not running tinc as root. Use sudo?\n");
174                         else
175                                 fprintf(stderr, "Check the permissions of each component of the path %s.\n", tinc_conf);
176                 }
177                 return 1;
178         }
179
180         char *name = get_my_name(true);
181         if(!name) {
182                 fprintf(stderr, "ERROR: tinc cannot run without a valid Name.\n");
183                 return 1;
184         }
185
186         // Check for private keys.
187         // TODO: use RSAPrivateKeyFile and Ed25519PrivateKeyFile variables if present.
188
189         struct stat st;
190         char fname[PATH_MAX];
191         char dname[PATH_MAX];
192
193 #ifndef DISABLE_LEGACY
194         rsa_t *rsa_priv = NULL;
195         snprintf(fname, sizeof fname, "%s/rsa_key.priv", confbase);
196
197         if(stat(fname, &st)) {
198                 if(errno != ENOENT) {
199                         // Something is seriously wrong here. If we can access the directory with tinc.conf in it, we should certainly be able to stat() an existing file.
200                         fprintf(stderr, "ERROR: cannot read %s: %s\n", fname, strerror(errno));
201                         fprintf(stderr, "Please correct this error.\n");
202                         return 1;
203                 }
204         } else {
205                 FILE *f = fopen(fname, "r");
206                 if(!f) {
207                         fprintf(stderr, "ERROR: could not open %s: %s\n", fname, strerror(errno));
208                         return 1;
209                 }
210                 rsa_priv = rsa_read_pem_private_key(f);
211                 fclose(f);
212                 if(!rsa_priv) {
213                         fprintf(stderr, "ERROR: No key or unusable key found in %s.\n", fname);
214                         fprintf(stderr, "You can generate a new RSA key with:\n\n");
215                         print_tinc_cmd(argv0, "generate-rsa-keys");
216                         return 1;
217                 }
218
219 #if !defined(HAVE_MINGW) && !defined(HAVE_CYGWIN)
220                 if(st.st_mode & 077) {
221                         fprintf(stderr, "WARNING: unsafe file permissions on %s.\n", fname);
222                         if(st.st_uid != uid) {
223                                 fprintf(stderr, "You are not running %s as the same uid as %s.\n", argv0, fname);
224                         } else if(ask_fix()) {
225                                 if(chmod(fname, st.st_mode & ~077))
226                                         fprintf(stderr, "ERROR: could not change permissions of %s: %s\n", fname, strerror(errno));
227                                 else
228                                         fprintf(stderr, "Fixed permissions of %s.\n", fname);
229                         }
230                 }
231 #endif
232         }
233 #endif
234
235         ecdsa_t *ecdsa_priv = NULL;
236         snprintf(fname, sizeof fname, "%s/ed25519_key.priv", confbase);
237
238         if(stat(fname, &st)) {
239                 if(errno != ENOENT) {
240                         // Something is seriously wrong here. If we can access the directory with tinc.conf in it, we should certainly be able to stat() an existing file.
241                         fprintf(stderr, "ERROR: cannot read %s: %s\n", fname, strerror(errno));
242                         fprintf(stderr, "Please correct this error.\n");
243                         return 1;
244                 }
245         } else {
246                 FILE *f = fopen(fname, "r");
247                 if(!f) {
248                         fprintf(stderr, "ERROR: could not open %s: %s\n", fname, strerror(errno));
249                         return 1;
250                 }
251                 ecdsa_priv = ecdsa_read_pem_private_key(f);
252                 fclose(f);
253                 if(!ecdsa_priv) {
254                         fprintf(stderr, "ERROR: No key or unusable key found in %s.\n", fname);
255                         fprintf(stderr, "You can generate a new Ed25519 key with:\n\n");
256                         print_tinc_cmd(argv0, "generate-ed25519-keys");
257                         return 1;
258                 }
259
260 #if !defined(HAVE_MINGW) && !defined(HAVE_CYGWIN)
261                 if(st.st_mode & 077) {
262                         fprintf(stderr, "WARNING: unsafe file permissions on %s.\n", fname);
263                         if(st.st_uid != uid) {
264                                 fprintf(stderr, "You are not running %s as the same uid as %s.\n", argv0, fname);
265                         } else if(ask_fix()) {
266                                 if(chmod(fname, st.st_mode & ~077))
267                                         fprintf(stderr, "ERROR: could not change permissions of %s: %s\n", fname, strerror(errno));
268                                 else
269                                         fprintf(stderr, "Fixed permissions of %s.\n", fname);
270                         }
271                 }
272 #endif
273         }
274
275 #ifdef DISABLE_LEGACY
276         if(!ecdsa_priv) {
277                 fprintf(stderr, "ERROR: No Ed25519 private key found.\n");
278 #else
279         if(!rsa_priv && !ecdsa_priv) {
280                 fprintf(stderr, "ERROR: Neither RSA or Ed25519 private key found.\n");
281 #endif
282                 fprintf(stderr, "You can generate new keys with:\n\n");
283                 print_tinc_cmd(argv0, "generate-keys");
284                 return 1;
285         }
286
287         // Check for public keys.
288         // TODO: use RSAPublicKeyFile variable if present.
289
290         snprintf(fname, sizeof fname, "%s/hosts/%s", confbase, name);
291         if(access(fname, R_OK))
292                 fprintf(stderr, "WARNING: cannot read %s\n", fname);
293
294         FILE *f;
295
296 #ifndef DISABLE_LEGACY
297         rsa_t *rsa_pub = NULL;
298
299         f = fopen(fname, "r");
300         if(f)
301                 rsa_pub = rsa_read_pem_public_key(f);
302         fclose(f);
303
304         if(rsa_priv) {
305                 if(!rsa_pub) {
306                         fprintf(stderr, "WARNING: No (usable) public RSA key found.\n");
307                         if(ask_fix()) {
308                                 FILE *f = fopen(fname, "a");
309                                 if(f) {
310                                         if(rsa_write_pem_public_key(rsa_priv, f))
311                                                 fprintf(stderr, "Wrote RSA public key to %s.\n", fname);
312                                         else
313                                                 fprintf(stderr, "ERROR: could not write RSA public key to %s.\n", fname);
314                                         fclose(f);
315                                 } else {
316                                         fprintf(stderr, "ERROR: could not append to %s: %s\n", fname, strerror(errno));
317                                 }
318                         }
319                 } else {
320                         // TODO: suggest remedies
321                         size_t len = rsa_size(rsa_priv);
322                         if(len != rsa_size(rsa_pub)) {
323                                 fprintf(stderr, "ERROR: public and private RSA keys do not match.\n");
324                                 return 1;
325                         }
326                         char buf1[len], buf2[len], buf3[len];
327                         randomize(buf1, sizeof buf1);
328                         buf1[0] &= 0x7f;
329                         memset(buf2, 0, sizeof buf2);
330                         memset(buf3, 0, sizeof buf2);
331                         if(!rsa_public_encrypt(rsa_pub, buf1, sizeof buf1, buf2)) {
332                                 fprintf(stderr, "ERROR: public RSA key does not work.\n");
333                                 return 1;
334                         }
335                         if(!rsa_private_decrypt(rsa_priv, buf2, sizeof buf2, buf3)) {
336                                 fprintf(stderr, "ERROR: private RSA key does not work.\n");
337                                 return 1;
338                         }
339                         if(memcmp(buf1, buf3, sizeof buf1)) {
340                                 fprintf(stderr, "ERROR: public and private RSA keys do not match.\n");
341                                 return 1;
342                         }
343                 }
344         } else {
345                 if(rsa_pub)
346                         fprintf(stderr, "WARNING: A public RSA key was found but no private key is known.\n");
347         }
348 #endif
349
350         ecdsa_t *ecdsa_pub = NULL;
351
352         f = fopen(fname, "r");
353         if(f) {
354                 ecdsa_pub = get_pubkey(f);
355                 if(!f) {
356                         rewind(f);
357                         ecdsa_pub = ecdsa_read_pem_public_key(f);
358                 }
359         }
360         fclose(f);
361
362         if(ecdsa_priv) {
363                 if(!ecdsa_pub) {
364                         fprintf(stderr, "WARNING: No (usable) public Ed25519 key found.\n");
365                         if(ask_fix()) {
366                                 FILE *f = fopen(fname, "a");
367                                 if(f) {
368                                         if(ecdsa_write_pem_public_key(ecdsa_priv, f))
369                                                 fprintf(stderr, "Wrote Ed25519 public key to %s.\n", fname);
370                                         else
371                                                 fprintf(stderr, "ERROR: could not write Ed25519 public key to %s.\n", fname);
372                                         fclose(f);
373                                 } else {
374                                         fprintf(stderr, "ERROR: could not append to %s: %s\n", fname, strerror(errno));
375                                 }
376                         }
377                 } else {
378                         // TODO: suggest remedies
379                         char *key1 = ecdsa_get_base64_public_key(ecdsa_pub);
380                         if(!key1) {
381                                 fprintf(stderr, "ERROR: public Ed25519 key does not work.\n");
382                                 return 1;
383                         }
384                         char *key2 = ecdsa_get_base64_public_key(ecdsa_priv);
385                         if(!key2) {
386                                 free(key1);
387                                 fprintf(stderr, "ERROR: private Ed25519 key does not work.\n");
388                                 return 1;
389                         }
390                         int result = strcmp(key1, key2);
391                         free(key1);
392                         free(key2);
393                         if(result) {
394                                 fprintf(stderr, "ERROR: public and private Ed25519 keys do not match.\n");
395                                 return 1;
396                         }
397                 }
398         } else {
399                 if(ecdsa_pub)
400                         fprintf(stderr, "WARNING: A public Ed25519 key was found but no private key is known.\n");
401         }
402
403         // Check whether scripts are executable
404
405         struct dirent *ent;
406         DIR *dir = opendir(confbase);
407         if(!dir) {
408                 fprintf(stderr, "ERROR: cannot read directory %s: %s\n", confbase, strerror(errno));
409                 return 1;
410         }
411
412         while((ent = readdir(dir))) {
413                 if(strtailcmp(ent->d_name, "-up") && strtailcmp(ent->d_name, "-down"))
414                         continue;
415
416                 strncpy(fname, ent->d_name, sizeof fname);
417                 char *dash = strrchr(fname, '-');
418                 if(!dash)
419                         continue;
420                 *dash = 0;
421
422                 if(strcmp(fname, "tinc") && strcmp(fname, "host") && strcmp(fname, "subnet")) {
423                         static bool explained = false;
424                         fprintf(stderr, "WARNING: Unknown script %s" SLASH "%s found.\n", confbase, ent->d_name);
425                         if(!explained) {
426                                 fprintf(stderr, "The only scripts in %s executed by tinc are:\n", confbase);
427                                 fprintf(stderr, "tinc-up, tinc-down, host-up, host-down, subnet-up and subnet-down.\n");
428                                 explained = true;
429                         }
430                         continue;
431                 }
432
433                 snprintf(fname, sizeof fname, "%s" SLASH "%s", confbase, ent->d_name);
434                 if(access(fname, R_OK | X_OK)) {
435                         if(errno != EACCES) {
436                                 fprintf(stderr, "ERROR: cannot access %s: %s\n", fname, strerror(errno));
437                                 continue;
438                         }
439                         fprintf(stderr, "WARNING: cannot read and execute %s: %s\n", fname, strerror(errno));
440                         if(ask_fix()) {
441                                 if(chmod(fname, 0755))
442                                         fprintf(stderr, "ERROR: cannot change permissions on %s: %s\n", fname, strerror(errno));
443                         }
444                 }
445         }
446         closedir(dir);
447
448         snprintf(dname, sizeof dname, "%s" SLASH "hosts", confbase);
449         dir = opendir(dname);
450         if(!dir) {
451                 fprintf(stderr, "ERROR: cannot read directory %s: %s\n", dname, strerror(errno));
452                 return 1;
453         }
454
455         while((ent = readdir(dir))) {
456                 if(strtailcmp(ent->d_name, "-up") && strtailcmp(ent->d_name, "-down"))
457                         continue;
458
459                 strncpy(fname, ent->d_name, sizeof fname);
460                 char *dash = strrchr(fname, '-');
461                 if(!dash)
462                         continue;
463                 *dash = 0;
464
465                 snprintf(fname, sizeof fname, "%s" SLASH "hosts" SLASH "%s", confbase, ent->d_name);
466                 if(access(fname, R_OK | X_OK)) {
467                         if(errno != EACCES) {
468                                 fprintf(stderr, "ERROR: cannot access %s: %s\n", fname, strerror(errno));
469                                 continue;
470                         }
471                         fprintf(stderr, "WARNING: cannot read and execute %s: %s\n", fname, strerror(errno));
472                         if(ask_fix()) {
473                                 if(chmod(fname, 0755))
474                                         fprintf(stderr, "ERROR: cannot change permissions on %s: %s\n", fname, strerror(errno));
475                         }
476                 }
477         }
478         closedir(dir);
479         
480         // Check for obsolete / unsafe / unknown configuration variables.
481
482         check_conffile(tinc_conf, true);
483
484         dir = opendir(dname);
485         if(dir) {
486                 while((ent = readdir(dir))) {
487                         if(!check_id(ent->d_name))
488                                 continue;
489
490                         snprintf(fname, sizeof fname, "%s" SLASH "hosts" SLASH "%s", confbase, ent->d_name);
491                         check_conffile(fname, false);
492                 }
493                 closedir(dir);
494         }
495
496         return 0;
497 }
498