1 /*
2  * Copyright (c) 2022 Stefan Sperling <stsp@openbsd.org>
3  * Copyright (c) 2016-2019, 2020-2021 Tracey Emery <tracey@traceyemery.net>
4  * Copyright (c) 2004, 2005 Esben Norby <norby@openbsd.org>
5  * Copyright (c) 2004 Ryan McBride <mcbride@openbsd.org>
6  * Copyright (c) 2002, 2003, 2004 Henning Brauer <henning@openbsd.org>
7  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
8  * Copyright (c) 2001 Daniel Hartmeier.  All rights reserved.
9  * Copyright (c) 2001 Theo de Raadt.  All rights reserved.
10  *
11  * Permission to use, copy, modify, and distribute this software for any
12  * purpose with or without fee is hereby granted, provided that the above
13  * copyright notice and this permission notice appear in all copies.
14  *
15  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
16  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
17  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
18  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
19  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
20  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
21  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
22  */
23 
24 %{
25 #include <sys/time.h>
26 #include <sys/types.h>
27 #include <sys/queue.h>
28 #include <sys/stat.h>
29 
30 #include <ctype.h>
31 #include <err.h>
32 #include <errno.h>
33 #include <event.h>
34 #include <imsg.h>
35 #include <limits.h>
36 #include <sha1.h>
37 #include <stdarg.h>
38 #include <stdlib.h>
39 #include <stdio.h>
40 #include <string.h>
41 #include <syslog.h>
42 #include <unistd.h>
43 
44 #include "got_error.h"
45 #include "got_path.h"
46 
47 #include "log.h"
48 #include "gotd.h"
49 
50 TAILQ_HEAD(files, file)		 files = TAILQ_HEAD_INITIALIZER(files);
51 static struct file {
52 	TAILQ_ENTRY(file)	 entry;
53 	FILE			*stream;
54 	char			*name;
55 	int			 lineno;
56 	int			 errors;
57 } *file;
58 struct file	*newfile(const char *, int);
59 static void	 closefile(struct file *);
60 int		 check_file_secrecy(int, const char *);
61 int		 yyparse(void);
62 int		 yylex(void);
63 int		 yyerror(const char *, ...)
64     __attribute__((__format__ (printf, 1, 2)))
65     __attribute__((__nonnull__ (1)));
66 int		 kw_cmp(const void *, const void *);
67 int		 lookup(char *);
68 int		 lgetc(int);
69 int		 lungetc(int);
70 int		 findeol(void);
71 
72 TAILQ_HEAD(symhead, sym)	 symhead = TAILQ_HEAD_INITIALIZER(symhead);
73 struct sym {
74 	TAILQ_ENTRY(sym)	 entry;
75 	int			 used;
76 	int			 persist;
77 	char			*nam;
78 	char			*val;
79 };
80 
81 int	 symset(const char *, const char *, int);
82 char	*symget(const char *);
83 
84 static int		 errors;
85 
86 static struct gotd		*gotd;
87 static struct gotd_repo		*new_repo;
88 static struct gotd_repo		*conf_new_repo(const char *);
89 static enum gotd_procid		 gotd_proc_id;
90 
91 typedef struct {
92 	union {
93 		long long	 number;
94 		char		*string;
95 	} v;
96 	int lineno;
97 } YYSTYPE;
98 
99 %}
100 
101 %token	PATH ERROR ON UNIX_SOCKET UNIX_GROUP USER REPOSITORY PERMIT DENY
102 
103 %token	<v.string>	STRING
104 %token	<v.number>	NUMBER
105 %type	<v.number>	boolean
106 
107 %%
108 
109 grammar		:
110 		| grammar '\n'
111 		| grammar main '\n'
112 		| grammar repository '\n'
113 		;
114 
115 boolean		: STRING {
116 			if (strcasecmp($1, "1") == 0 ||
117 			    strcasecmp($1, "yes") == 0 ||
118 			    strcasecmp($1, "on") == 0)
119 				$$ = 1;
120 			else if (strcasecmp($1, "0") == 0 ||
121 			    strcasecmp($1, "off") == 0 ||
122 			    strcasecmp($1, "no") == 0)
123 				$$ = 0;
124 			else {
125 				yyerror("invalid boolean value '%s'", $1);
126 				free($1);
127 				YYERROR;
128 			}
129 			free($1);
130 		}
131 		| ON { $$ = 1; }
132 		| NUMBER { $$ = $1; }
133 		;
134 
135 main		: UNIX_SOCKET STRING {
136 			if (gotd_proc_id == PROC_GOTD) {
137 				if (strlcpy(gotd->unix_socket_path, $2,
138 				    sizeof(gotd->unix_socket_path)) >=
139 				    sizeof(gotd->unix_socket_path)) {
140 					yyerror("%s: unix socket path too long",
141 					    __func__);
142 					free($2);
143 					YYERROR;
144 				}
145 			}
146 			free($2);
147 		}
148 		| UNIX_GROUP STRING {
149 			if (strlcpy(gotd->unix_group_name, $2,
150 			    sizeof(gotd->unix_group_name)) >=
151 			    sizeof(gotd->unix_group_name)) {
152 				yyerror("%s: unix group name too long",
153 				    __func__);
154 				free($2);
155 				YYERROR;
156 			}
157 			free($2);
158 		}
159 		| USER STRING {
160 			if (strlcpy(gotd->user_name, $2,
161 			    sizeof(gotd->user_name)) >=
162 			    sizeof(gotd->user_name)) {
163 				yyerror("%s: user name too long", __func__);
164 				free($2);
165 				YYERROR;
166 			}
167 			free($2);
168 		}
169 		;
170 
171 repository	: REPOSITORY STRING {
172 			struct gotd_repo *repo;
173 
174 			TAILQ_FOREACH(repo, &gotd->repos, entry) {
175 				if (strcmp(repo->name, $2) == 0) {
176 					yyerror("duplicate repository '%s'", $2);
177 					free($2);
178 					YYERROR;
179 				}
180 			}
181 
182 			if (gotd_proc_id == PROC_GOTD) {
183 				new_repo = conf_new_repo($2);
184 			}
185 			free($2);
186 		}
187 		| REPOSITORY STRING {
188 			struct gotd_repo *repo;
189 
190 			TAILQ_FOREACH(repo, &gotd->repos, entry) {
191 				if (strcmp(repo->name, $2) == 0) {
192 					yyerror("duplicate repository '%s'", $2);
193 					free($2);
194 					YYERROR;
195 				}
196 			}
197 
198 			if (gotd_proc_id == PROC_GOTD) {
199 				new_repo = conf_new_repo($2);
200 			}
201 			free($2);
202 		} '{' optnl repoopts2 '}' {
203 		}
204 		;
205 
206 repoopts1	: PATH STRING {
207 			if (gotd_proc_id == PROC_GOTD) {
208 				if (!got_path_is_absolute($2)) {
209 					yyerror("%s: path %s is not absolute",
210 					    __func__, $2);
211 					free($2);
212 					YYERROR;
213 				}
214 				if (strlcpy(new_repo->path, $2,
215 				    sizeof(new_repo->path)) >=
216 				    sizeof(new_repo->path)) {
217 					yyerror("%s: path truncated", __func__);
218 					free($2);
219 					YYERROR;
220 				}
221 			}
222 			free($2);
223 		}
224 		| PERMIT RO STRING {
225 			if (gotd_proc_id == PROC_GOTD) {
226 				conf_new_access_rule(new_repo,
227 				    GOTD_ACCESS_PERMITTED, GOTD_AUTH_READ, $3);
228 			}
229 		}
230 		| PERMIT RW STRING {
231 			if (gotd_proc_id == PROC_GOTD) {
232 				conf_new_access_rule(new_repo,
233 				    GOTD_ACCESS_PERMITTED,
234 				    GOTD_AUTH_READ | GOTD_AUTH_WRITE, $3);
235 			}
236 		}
237 		| DENY STRING {
238 			if (gotd_proc_id == PROC_GOTD) {
239 				conf_new_access_rule(new_repo,
240 				    GOTD_ACCESS_DENIED, 0, $2);
241 			}
242 		}
243 		;
244 
245 repoopts2	: repoopts2 repoopts1 nl
246 		| repoopts1 optnl
247 		;
248 
249 nl		: '\n' optnl
250 		;
251 
252 optnl		: '\n' optnl		/* zero or more newlines */
253 		| /* empty */
254 		;
255 
256 %%
257 
258 struct keywords {
259 	const char	*k_name;
260 	int		 k_val;
261 };
262 
263 int
264 yyerror(const char *fmt, ...)
265 {
266 	va_list ap;
267 	char *msg;
268 
269 	file->errors++;
270 	va_start(ap, fmt);
271 	if (vasprintf(&msg, fmt, ap) == -1)
272 		fatalx("yyerror vasprintf");
273 	va_end(ap);
274 	logit(LOG_CRIT, "%s:%d: %s", file->name, yylval.lineno, msg);
275 	free(msg);
276 	return (0);
277 }
278 
279 int
280 kw_cmp(const void *k, const void *e)
281 {
282 	return (strcmp(k, ((const struct keywords *)e)->k_name));
283 }
284 
285 int
286 lookup(char *s)
287 {
288 	/* This has to be sorted always. */
289 	static const struct keywords keywords[] = {
290 		{ "deny",			DENY },
291 		{ "on",				ON },
292 		{ "path",			PATH },
293 		{ "permit",			PERMIT },
294 		{ "repository",			REPOSITORY },
295 		{ "ro",				RO },
296 		{ "rw",				RW },
297 		{ "unix_group",			UNIX_GROUP },
298 		{ "unix_socket",		UNIX_SOCKET },
299 		{ "user",			USER },
300 	};
301 	const struct keywords *p;
302 
303 	p = bsearch(s, keywords, sizeof(keywords)/sizeof(keywords[0]),
304 	    sizeof(keywords[0]), kw_cmp);
305 
306 	if (p)
307 		return (p->k_val);
308 	else
309 		return (STRING);
310 }
311 
312 #define MAXPUSHBACK	128
313 
314 unsigned char *parsebuf;
315 int parseindex;
316 unsigned char pushback_buffer[MAXPUSHBACK];
317 int pushback_index = 0;
318 
319 int
320 lgetc(int quotec)
321 {
322 	int c, next;
323 
324 	if (parsebuf) {
325 		/* Read character from the parsebuffer instead of input. */
326 		if (parseindex >= 0) {
327 			c = parsebuf[parseindex++];
328 			if (c != '\0')
329 				return (c);
330 			parsebuf = NULL;
331 		} else
332 			parseindex++;
333 	}
334 
335 	if (pushback_index)
336 		return (pushback_buffer[--pushback_index]);
337 
338 	if (quotec) {
339 		c = getc(file->stream);
340 		if (c == EOF)
341 			yyerror("reached end of file while parsing "
342 			    "quoted string");
343 		return (c);
344 	}
345 
346 	c = getc(file->stream);
347 	while (c == '\\') {
348 		next = getc(file->stream);
349 		if (next != '\n') {
350 			c = next;
351 			break;
352 		}
353 		yylval.lineno = file->lineno;
354 		file->lineno++;
355 		c = getc(file->stream);
356 	}
357 
358 	return (c);
359 }
360 
361 int
362 lungetc(int c)
363 {
364 	if (c == EOF)
365 		return (EOF);
366 	if (parsebuf) {
367 		parseindex--;
368 		if (parseindex >= 0)
369 			return (c);
370 	}
371 	if (pushback_index < MAXPUSHBACK-1)
372 		return (pushback_buffer[pushback_index++] = c);
373 	else
374 		return (EOF);
375 }
376 
377 int
378 findeol(void)
379 {
380 	int c;
381 
382 	parsebuf = NULL;
383 
384 	/* Skip to either EOF or the first real EOL. */
385 	while (1) {
386 		if (pushback_index)
387 			c = pushback_buffer[--pushback_index];
388 		else
389 			c = lgetc(0);
390 		if (c == '\n') {
391 			file->lineno++;
392 			break;
393 		}
394 		if (c == EOF)
395 			break;
396 	}
397 	return (ERROR);
398 }
399 
400 int
401 yylex(void)
402 {
403 	unsigned char buf[8096];
404 	unsigned char *p, *val;
405 	int quotec, next, c;
406 	int token;
407 
408 top:
409 	p = buf;
410 	c = lgetc(0);
411 	while (c == ' ' || c == '\t')
412 		c = lgetc(0); /* nothing */
413 
414 	yylval.lineno = file->lineno;
415 	if (c == '#') {
416 		c = lgetc(0);
417 		while (c != '\n' && c != EOF)
418 			c = lgetc(0); /* nothing */
419 	}
420 	if (c == '$' && parsebuf == NULL) {
421 		while (1) {
422 			c = lgetc(0);
423 			if (c == EOF)
424 				return (0);
425 
426 			if (p + 1 >= buf + sizeof(buf) - 1) {
427 				yyerror("string too long");
428 				return (findeol());
429 			}
430 			if (isalnum(c) || c == '_') {
431 				*p++ = c;
432 				continue;
433 			}
434 			*p = '\0';
435 			lungetc(c);
436 			break;
437 		}
438 		val = symget(buf);
439 		if (val == NULL) {
440 			yyerror("macro '%s' not defined", buf);
441 			return (findeol());
442 		}
443 		parsebuf = val;
444 		parseindex = 0;
445 		goto top;
446 	}
447 
448 	switch (c) {
449 	case '\'':
450 	case '"':
451 		quotec = c;
452 		while (1) {
453 			c = lgetc(quotec);
454 			if (c == EOF)
455 				return (0);
456 			if (c == '\n') {
457 				file->lineno++;
458 				continue;
459 			} else if (c == '\\') {
460 				next = lgetc(quotec);
461 				if (next == EOF)
462 					return (0);
463 				if (next == quotec || c == ' ' || c == '\t')
464 					c = next;
465 				else if (next == '\n') {
466 					file->lineno++;
467 					continue;
468 				} else
469 					lungetc(next);
470 			} else if (c == quotec) {
471 				*p = '\0';
472 				break;
473 			} else if (c == '\0') {
474 				yyerror("syntax error");
475 				return (findeol());
476 			}
477 			if (p + 1 >= buf + sizeof(buf) - 1) {
478 				yyerror("string too long");
479 				return (findeol());
480 			}
481 			*p++ = c;
482 		}
483 		yylval.v.string = strdup(buf);
484 		if (yylval.v.string == NULL)
485 			err(1, "yylex: strdup");
486 		return (STRING);
487 	}
488 
489 #define allowed_to_end_number(x) \
490 	(isspace(x) || x == ')' || x ==',' || x == '/' || x == '}' || x == '=')
491 
492 	if (c == '-' || isdigit(c)) {
493 		do {
494 			*p++ = c;
495 			if ((unsigned)(p-buf) >= sizeof(buf)) {
496 				yyerror("string too long");
497 				return (findeol());
498 			}
499 			c = lgetc(0);
500 		} while (c != EOF && isdigit(c));
501 		lungetc(c);
502 		if (p == buf + 1 && buf[0] == '-')
503 			goto nodigits;
504 		if (c == EOF || allowed_to_end_number(c)) {
505 			const char *errstr = NULL;
506 
507 			*p = '\0';
508 			yylval.v.number = strtonum(buf, LLONG_MIN,
509 			    LLONG_MAX, &errstr);
510 			if (errstr) {
511 				yyerror("\"%s\" invalid number: %s",
512 				    buf, errstr);
513 				return (findeol());
514 			}
515 			return (NUMBER);
516 		} else {
517 nodigits:
518 			while (p > buf + 1)
519 				lungetc(*--p);
520 			c = *--p;
521 			if (c == '-')
522 				return (c);
523 		}
524 	}
525 
526 #define allowed_in_string(x) \
527 	(isalnum(x) || (ispunct(x) && x != '(' && x != ')' && \
528 	x != '{' && x != '}' && \
529 	x != '!' && x != '=' && x != '#' && \
530 	x != ','))
531 
532 	if (isalnum(c) || c == ':' || c == '_') {
533 		do {
534 			*p++ = c;
535 			if ((unsigned)(p-buf) >= sizeof(buf)) {
536 				yyerror("string too long");
537 				return (findeol());
538 			}
539 			c = lgetc(0);
540 		} while (c != EOF && (allowed_in_string(c)));
541 		lungetc(c);
542 		*p = '\0';
543 		token = lookup(buf);
544 		if (token == STRING) {
545 			yylval.v.string = strdup(buf);
546 			if (yylval.v.string == NULL)
547 				err(1, "yylex: strdup");
548 		}
549 		return (token);
550 	}
551 	if (c == '\n') {
552 		yylval.lineno = file->lineno;
553 		file->lineno++;
554 	}
555 	if (c == EOF)
556 		return (0);
557 	return (c);
558 }
559 
560 int
561 check_file_secrecy(int fd, const char *fname)
562 {
563 	struct stat st;
564 
565 	if (fstat(fd, &st)) {
566 		log_warn("cannot stat %s", fname);
567 		return (-1);
568 	}
569 	if (st.st_uid != 0 && st.st_uid != getuid()) {
570 		log_warnx("%s: owner not root or current user", fname);
571 		return (-1);
572 	}
573 	if (st.st_mode & (S_IWGRP | S_IXGRP | S_IRWXO)) {
574 		log_warnx("%s: group writable or world read/writable", fname);
575 		return (-1);
576 	}
577 	return (0);
578 }
579 
580 struct file *
581 newfile(const char *name, int secret)
582 {
583 	struct file *nfile;
584 
585 	nfile = calloc(1, sizeof(struct file));
586 	if (nfile == NULL) {
587 		log_warn("calloc");
588 		return (NULL);
589 	}
590 	nfile->name = strdup(name);
591 	if (nfile->name == NULL) {
592 		log_warn("strdup");
593 		free(nfile);
594 		return (NULL);
595 	}
596 	nfile->stream = fopen(nfile->name, "r");
597 	if (nfile->stream == NULL) {
598 		/* no warning, we don't require a conf file */
599 		free(nfile->name);
600 		free(nfile);
601 		return (NULL);
602 	} else if (secret &&
603 	    check_file_secrecy(fileno(nfile->stream), nfile->name)) {
604 		fclose(nfile->stream);
605 		free(nfile->name);
606 		free(nfile);
607 		return (NULL);
608 	}
609 	nfile->lineno = 1;
610 	return (nfile);
611 }
612 
613 static void
614 closefile(struct file *xfile)
615 {
616 	fclose(xfile->stream);
617 	free(xfile->name);
618 	free(xfile);
619 }
620 
621 int
622 parse_config(const char *filename, enum gotd_procid proc_id,
623     struct gotd *env)
624 {
625 	struct sym *sym, *next;
626 
627 	memset(env, 0, sizeof(*env));
628 
629 	gotd = env;
630 	gotd_proc_id = proc_id;
631 	TAILQ_INIT(&gotd->repos);
632 
633 	/* Apply default values. */
634 	if (strlcpy(gotd->unix_socket_path, GOTD_UNIX_SOCKET,
635 	    sizeof(gotd->unix_socket_path)) >= sizeof(gotd->unix_socket_path)) {
636 		fprintf(stderr, "%s: unix socket path too long", __func__);
637 		return -1;
638 	}
639 	if (strlcpy(gotd->unix_group_name, GOTD_UNIX_GROUP,
640 	    sizeof(gotd->unix_group_name)) >= sizeof(gotd->unix_group_name)) {
641 		fprintf(stderr, "%s: unix group name too long", __func__);
642 		return -1;
643 	}
644 	if (strlcpy(gotd->user_name, GOTD_USER,
645 	    sizeof(gotd->user_name)) >= sizeof(gotd->user_name)) {
646 		fprintf(stderr, "%s: user name too long", __func__);
647 		return -1;
648 	}
649 
650 	file = newfile(filename, 0);
651 	if (file == NULL) {
652 		/* just return, as we don't require a conf file */
653 		return (0);
654 	}
655 
656 	yyparse();
657 	errors = file->errors;
658 	closefile(file);
659 
660 	/* Free macros and check which have not been used. */
661 	TAILQ_FOREACH_SAFE(sym, &symhead, entry, next) {
662 		if ((gotd->verbosity > 1) && !sym->used)
663 			fprintf(stderr, "warning: macro '%s' not used\n",
664 			    sym->nam);
665 		if (!sym->persist) {
666 			free(sym->nam);
667 			free(sym->val);
668 			TAILQ_REMOVE(&symhead, sym, entry);
669 			free(sym);
670 		}
671 	}
672 
673 	if (errors)
674 		return (-1);
675 
676 	return (0);
677 }
678 
679 static struct gotd_repo *
680 conf_new_repo(const char *name)
681 {
682 	struct gotd_repo *repo;
683 
684 	if (strchr(name, '\n') != NULL) {
685 		fatalx("%s: repository names must not contain linefeeds: %s",
686 		    getprogname(), name);
687 	}
688 
689 	repo = calloc(1, sizeof(*repo));
690 	if (repo == NULL)
691 		fatalx("%s: calloc", __func__);
692 
693 	STAILQ_INIT(&repo->rules);
694 
695 	if (strlcpy(repo->name, name, sizeof(repo->name)) >=
696 	    sizeof(repo->name))
697 		fatalx("%s: strlcpy", __func__);
698 
699 	TAILQ_INSERT_TAIL(&gotd->repos, repo, entry);
700 	gotd->nrepos++;
701 
702 	return repo;
703 };
704 
705 static void
706 conf_new_access_rule(struct gotd_repo *repo, enum gotd_access access,
707     int authorization, char *identifier)
708 {
709 	struct gotd_access_rule *rule;
710 
711 	rule = calloc(1, sizeof(*rule));
712 	if (rule == NULL)
713 		fatal("calloc");
714 
715 	rule->access = access;
716 	rule->authorization = authorization;
717 	rule->identifier = identifier;
718 
719 	STAILQ_INSERT_TAIL(&repo->rules, rule, entry);
720 }
721 
722 int
723 symset(const char *nam, const char *val, int persist)
724 {
725 	struct sym *sym;
726 
727 	TAILQ_FOREACH(sym, &symhead, entry) {
728 		if (strcmp(nam, sym->nam) == 0)
729 			break;
730 	}
731 
732 	if (sym != NULL) {
733 		if (sym->persist == 1)
734 			return (0);
735 		else {
736 			free(sym->nam);
737 			free(sym->val);
738 			TAILQ_REMOVE(&symhead, sym, entry);
739 			free(sym);
740 		}
741 	}
742 	sym = calloc(1, sizeof(*sym));
743 	if (sym == NULL)
744 		return (-1);
745 
746 	sym->nam = strdup(nam);
747 	if (sym->nam == NULL) {
748 		free(sym);
749 		return (-1);
750 	}
751 	sym->val = strdup(val);
752 	if (sym->val == NULL) {
753 		free(sym->nam);
754 		free(sym);
755 		return (-1);
756 	}
757 	sym->used = 0;
758 	sym->persist = persist;
759 	TAILQ_INSERT_TAIL(&symhead, sym, entry);
760 	return (0);
761 }
762 
763 char *
764 symget(const char *nam)
765 {
766 	struct sym *sym;
767 
768 	TAILQ_FOREACH(sym, &symhead, entry) {
769 		if (strcmp(nam, sym->nam) == 0) {
770 			sym->used = 1;
771 			return (sym->val);
772 		}
773 	}
774 	return (NULL);
775 }