libmap.c revision 270756 
1/*
2 * $FreeBSD: stable/10/libexec/rtld-elf/libmap.c 270756 2014-08-28 18:11:05Z pfg $
3 */
4
5#include <sys/types.h>
6#include <sys/param.h>
7#include <sys/fcntl.h>
8#include <sys/mman.h>
9#include <sys/queue.h>
10#include <sys/stat.h>
11#include <dirent.h>
12#include <errno.h>
13#include <stdlib.h>
14#include <string.h>
15
16#include "debug.h"
17#include "rtld.h"
18#include "libmap.h"
19
20#ifndef _PATH_LIBMAP_CONF
21#define	_PATH_LIBMAP_CONF	"/etc/libmap.conf"
22#endif
23
24#ifdef COMPAT_32BIT
25#undef _PATH_LIBMAP_CONF
26#define	_PATH_LIBMAP_CONF	"/etc/libmap32.conf"
27#endif
28
29TAILQ_HEAD(lm_list, lm);
30struct lm {
31	char *f;
32	char *t;
33	TAILQ_ENTRY(lm)	lm_link;
34};
35
36TAILQ_HEAD(lmp_list, lmp) lmp_head = TAILQ_HEAD_INITIALIZER(lmp_head);
37struct lmp {
38	char *p;
39	enum { T_EXACT=0, T_BASENAME, T_DIRECTORY } type;
40	struct lm_list lml;
41	TAILQ_ENTRY(lmp) lmp_link;
42};
43
44static TAILQ_HEAD(lmc_list, lmc) lmc_head = TAILQ_HEAD_INITIALIZER(lmc_head);
45struct lmc {
46	char *path;
47	TAILQ_ENTRY(lmc) next;
48};
49
50static int lm_count;
51
52static void lmc_parse(char *, size_t);
53static void lmc_parse_file(char *);
54static void lmc_parse_dir(char *);
55static void lm_add(const char *, const char *, const char *);
56static void lm_free(struct lm_list *);
57static char *lml_find(struct lm_list *, const char *);
58static struct lm_list *lmp_find(const char *);
59static struct lm_list *lmp_init(char *);
60static const char *quickbasename(const char *);
61
62#define	iseol(c)	(((c) == '#') || ((c) == '\0') || \
63			 ((c) == '\n') || ((c) == '\r'))
64
65/*
66 * Do not use ctype.h macros, which rely on working TLS.  It is
67 * too early to have thread-local variables functional.
68 */
69#define	rtld_isspace(c)	((c) == ' ' || (c) == '\t')
70
71int
72lm_init(char *libmap_override)
73{
74	char *p;
75
76	dbg("lm_init(\"%s\")", libmap_override);
77	TAILQ_INIT(&lmp_head);
78
79	lmc_parse_file(_PATH_LIBMAP_CONF);
80
81	if (libmap_override) {
82		/*
83		 * Do some character replacement to make $LDLIBMAP look
84		 * like a text file, then parse it.
85		 */
86		libmap_override = xstrdup(libmap_override);
87		for (p = libmap_override; *p; p++) {
88			switch (*p) {
89			case '=':
90				*p = ' ';
91				break;
92			case ',':
93				*p = '\n';
94				break;
95			}
96		}
97		lmc_parse(libmap_override, p - libmap_override);
98		free(libmap_override);
99	}
100
101	return (lm_count == 0);
102}
103
104static void
105lmc_parse_file(char *path)
106{
107	struct lmc *p;
108	struct stat st;
109	int fd;
110	char *rpath;
111	char *lm_map;
112
113	rpath = realpath(path, NULL);
114	if (rpath == NULL)
115		return;
116
117	TAILQ_FOREACH(p, &lmc_head, next) {
118		if (strcmp(p->path, rpath) == 0) {
119			free(rpath);
120			return;
121		}
122	}
123
124	fd = open(rpath, O_RDONLY | O_CLOEXEC);
125	if (fd == -1) {
126		dbg("lm_parse_file: open(\"%s\") failed, %s", rpath,
127		    rtld_strerror(errno));
128		free(rpath);
129		return;
130	}
131	if (fstat(fd, &st) == -1) {
132		close(fd);
133		dbg("lm_parse_file: fstat(\"%s\") failed, %s", rpath,
134		    rtld_strerror(errno));
135		free(rpath);
136		return;
137	}
138	lm_map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
139	if (lm_map == (const char *)MAP_FAILED) {
140		close(fd);
141		dbg("lm_parse_file: mmap(\"%s\") failed, %s", rpath,
142		    rtld_strerror(errno));
143		free(rpath);
144		return;
145	}
146	close(fd);
147	p = xmalloc(sizeof(struct lmc));
148	p->path = rpath;
149	TAILQ_INSERT_HEAD(&lmc_head, p, next);
150	lmc_parse(lm_map, st.st_size);
151	munmap(lm_map, st.st_size);
152}
153
154static void
155lmc_parse_dir(char *idir)
156{
157	DIR *d;
158	struct dirent *dp;
159	struct lmc *p;
160	char conffile[MAXPATHLEN];
161	char *ext;
162	char *rpath;
163
164	rpath = realpath(idir, NULL);
165	if (rpath == NULL)
166		return;
167
168	TAILQ_FOREACH(p, &lmc_head, next) {
169		if (strcmp(p->path, rpath) == 0) {
170			free(rpath);
171			return;
172		}
173	}
174	d = opendir(idir);
175	if (d == NULL) {
176		free(rpath);
177		return;
178	}
179
180	p = xmalloc(sizeof(struct lmc));
181	p->path = rpath;
182	TAILQ_INSERT_HEAD(&lmc_head, p, next);
183
184	while ((dp = readdir(d)) != NULL) {
185		if (dp->d_ino == 0)
186			continue;
187		if (dp->d_type != DT_REG)
188			continue;
189		ext = strrchr(dp->d_name, '.');
190		if (ext == NULL)
191			continue;
192		if (strcmp(ext, ".conf") != 0)
193			continue;
194		if (strlcpy(conffile, idir, MAXPATHLEN) >= MAXPATHLEN)
195			continue; /* too long */
196		if (strlcat(conffile, "/", MAXPATHLEN) >= MAXPATHLEN)
197			continue; /* too long */
198		if (strlcat(conffile, dp->d_name, MAXPATHLEN) >= MAXPATHLEN)
199			continue; /* too long */
200		lmc_parse_file(conffile);
201	}
202	closedir(d);
203}
204
205static void
206lmc_parse(char *lm_p, size_t lm_len)
207{
208	char *cp, *f, *t, *c, *p;
209	char prog[MAXPATHLEN];
210	/* allow includedir + full length path */
211	char line[MAXPATHLEN + 13];
212	size_t cnt;
213	int i;
214
215	cnt = 0;
216	p = NULL;
217	while (cnt < lm_len) {
218		i = 0;
219		while (cnt < lm_len && lm_p[cnt] != '\n' &&
220		    i < sizeof(line) - 1) {
221			line[i] = lm_p[cnt];
222			cnt++;
223			i++;
224		}
225		line[i] = '\0';
226		while (cnt < lm_len && lm_p[cnt] != '\n')
227			cnt++;
228		/* skip over nl */
229		cnt++;
230
231		cp = &line[0];
232		t = f = c = NULL;
233
234		/* Skip over leading space */
235		while (rtld_isspace(*cp)) cp++;
236
237		/* Found a comment or EOL */
238		if (iseol(*cp)) continue;
239
240		/* Found a constraint selector */
241		if (*cp == '[') {
242			cp++;
243
244			/* Skip leading space */
245			while (rtld_isspace(*cp)) cp++;
246
247			/* Found comment, EOL or end of selector */
248			if  (iseol(*cp) || *cp == ']')
249				continue;
250
251			c = cp++;
252			/* Skip to end of word */
253			while (!rtld_isspace(*cp) && !iseol(*cp) && *cp != ']')
254				cp++;
255
256			/* Skip and zero out trailing space */
257			while (rtld_isspace(*cp)) *cp++ = '\0';
258
259			/* Check if there is a closing brace */
260			if (*cp != ']') continue;
261
262			/* Terminate string if there was no trailing space */
263			*cp++ = '\0';
264
265			/*
266			 * There should be nothing except whitespace or comment
267			  from this point to the end of the line.
268			 */
269			while(rtld_isspace(*cp)) cp++;
270			if (!iseol(*cp)) continue;
271
272			if (strlcpy(prog, c, sizeof prog) >= sizeof prog)
273				continue;
274			p = prog;
275			continue;
276		}
277
278		/* Parse the 'from' candidate. */
279		f = cp++;
280		while (!rtld_isspace(*cp) && !iseol(*cp)) cp++;
281
282		/* Skip and zero out the trailing whitespace */
283		while (rtld_isspace(*cp)) *cp++ = '\0';
284
285		/* Found a comment or EOL */
286		if (iseol(*cp)) continue;
287
288		/* Parse 'to' mapping */
289		t = cp++;
290		while (!rtld_isspace(*cp) && !iseol(*cp)) cp++;
291
292		/* Skip and zero out the trailing whitespace */
293		while (rtld_isspace(*cp)) *cp++ = '\0';
294
295		/* Should be no extra tokens at this point */
296		if (!iseol(*cp)) continue;
297
298		*cp = '\0';
299		if (strcmp(f, "includedir") == 0)
300			lmc_parse_dir(t);
301		else if (strcmp(f, "include") == 0)
302			lmc_parse_file(t);
303		else
304			lm_add(p, f, t);
305	}
306}
307
308static void
309lm_free (struct lm_list *lml)
310{
311	struct lm *lm;
312
313	dbg("%s(%p)", __func__, lml);
314
315	while (!TAILQ_EMPTY(lml)) {
316		lm = TAILQ_FIRST(lml);
317		TAILQ_REMOVE(lml, lm, lm_link);
318		free(lm->f);
319		free(lm->t);
320		free(lm);
321	}
322	return;
323}
324
325void
326lm_fini (void)
327{
328	struct lmp *lmp;
329	struct lmc *p;
330
331	dbg("%s()", __func__);
332
333	while (!TAILQ_EMPTY(&lmc_head)) {
334		p = TAILQ_FIRST(&lmc_head);
335		TAILQ_REMOVE(&lmc_head, p, next);
336		free(p->path);
337		free(p);
338	}
339
340	while (!TAILQ_EMPTY(&lmp_head)) {
341		lmp = TAILQ_FIRST(&lmp_head);
342		TAILQ_REMOVE(&lmp_head, lmp, lmp_link);
343		free(lmp->p);
344		lm_free(&lmp->lml);
345		free(lmp);
346	}
347	return;
348}
349
350static void
351lm_add (const char *p, const char *f, const char *t)
352{
353	struct lm_list *lml;
354	struct lm *lm;
355
356	if (p == NULL)
357		p = "$DEFAULT$";
358
359	dbg("%s(\"%s\", \"%s\", \"%s\")", __func__, p, f, t);
360
361	if ((lml = lmp_find(p)) == NULL)
362		lml = lmp_init(xstrdup(p));
363
364	lm = xmalloc(sizeof(struct lm));
365	lm->f = xstrdup(f);
366	lm->t = xstrdup(t);
367	TAILQ_INSERT_HEAD(lml, lm, lm_link);
368	lm_count++;
369}
370
371char *
372lm_find (const char *p, const char *f)
373{
374	struct lm_list *lml;
375	char *t;
376
377	dbg("%s(\"%s\", \"%s\")", __func__, p, f);
378
379	if (p != NULL && (lml = lmp_find(p)) != NULL) {
380		t = lml_find(lml, f);
381		if (t != NULL) {
382			/*
383			 * Add a global mapping if we have
384			 * a successful constrained match.
385			 */
386			lm_add(NULL, f, t);
387			return (t);
388		}
389	}
390	lml = lmp_find("$DEFAULT$");
391	if (lml != NULL)
392		return (lml_find(lml, f));
393	else
394		return (NULL);
395}
396
397/* Given a libmap translation list and a library name, return the
398   replacement library, or NULL */
399char *
400lm_findn (const char *p, const char *f, const int n)
401{
402	char pathbuf[64], *s, *t;
403
404	if (n < sizeof(pathbuf) - 1)
405		s = pathbuf;
406	else
407		s = xmalloc(n + 1);
408	memcpy(s, f, n);
409	s[n] = '\0';
410	t = lm_find(p, s);
411	if (s != pathbuf)
412		free(s);
413	return (t);
414}
415
416static char *
417lml_find (struct lm_list *lmh, const char *f)
418{
419	struct lm *lm;
420
421	dbg("%s(%p, \"%s\")", __func__, lmh, f);
422
423	TAILQ_FOREACH(lm, lmh, lm_link)
424		if (strcmp(f, lm->f) == 0)
425			return (lm->t);
426	return (NULL);
427}
428
429/* Given an executable name, return a pointer to the translation list or
430   NULL if no matches */
431static struct lm_list *
432lmp_find (const char *n)
433{
434	struct lmp *lmp;
435
436	dbg("%s(\"%s\")", __func__, n);
437
438	TAILQ_FOREACH(lmp, &lmp_head, lmp_link)
439		if ((lmp->type == T_EXACT && strcmp(n, lmp->p) == 0) ||
440		    (lmp->type == T_DIRECTORY && strncmp(n, lmp->p, strlen(lmp->p)) == 0) ||
441		    (lmp->type == T_BASENAME && strcmp(quickbasename(n), lmp->p) == 0))
442			return (&lmp->lml);
443	return (NULL);
444}
445
446static struct lm_list *
447lmp_init (char *n)
448{
449	struct lmp *lmp;
450
451	dbg("%s(\"%s\")", __func__, n);
452
453	lmp = xmalloc(sizeof(struct lmp));
454	lmp->p = n;
455	if (n[strlen(n)-1] == '/')
456		lmp->type = T_DIRECTORY;
457	else if (strchr(n,'/') == NULL)
458		lmp->type = T_BASENAME;
459	else
460		lmp->type = T_EXACT;
461	TAILQ_INIT(&lmp->lml);
462	TAILQ_INSERT_HEAD(&lmp_head, lmp, lmp_link);
463
464	return (&lmp->lml);
465}
466
467/* libc basename is overkill.  Return a pointer to the character after the
468   last /, or the original string if there are no slashes. */
469static const char *
470quickbasename (const char *path)
471{
472	const char *p = path;
473	for (; *path; path++) {
474		if (*path == '/')
475			p = path+1;
476	}
477	return (p);
478}
479