libmap.c revision 290223 
1/*
2 * $FreeBSD: head/libexec/rtld-elf/libmap.c 290223 2015-10-31 04:39:55Z imp $
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#include "paths.h"
20
21TAILQ_HEAD(lm_list, lm);
22struct lm {
23	char *f;
24	char *t;
25	TAILQ_ENTRY(lm)	lm_link;
26};
27
28TAILQ_HEAD(lmp_list, lmp) lmp_head = TAILQ_HEAD_INITIALIZER(lmp_head);
29struct lmp {
30	char *p;
31	enum { T_EXACT=0, T_BASENAME, T_DIRECTORY } type;
32	struct lm_list lml;
33	TAILQ_ENTRY(lmp) lmp_link;
34};
35
36static TAILQ_HEAD(lmc_list, lmc) lmc_head = TAILQ_HEAD_INITIALIZER(lmc_head);
37struct lmc {
38	char *path;
39	TAILQ_ENTRY(lmc) next;
40};
41
42static int lm_count;
43
44static void lmc_parse(char *, size_t);
45static void lmc_parse_file(char *);
46static void lmc_parse_dir(char *);
47static void lm_add(const char *, const char *, const char *);
48static void lm_free(struct lm_list *);
49static char *lml_find(struct lm_list *, const char *);
50static struct lm_list *lmp_find(const char *);
51static struct lm_list *lmp_init(char *);
52static const char *quickbasename(const char *);
53
54#define	iseol(c)	(((c) == '#') || ((c) == '\0') || \
55			 ((c) == '\n') || ((c) == '\r'))
56
57/*
58 * Do not use ctype.h macros, which rely on working TLS.  It is
59 * too early to have thread-local variables functional.
60 */
61#define	rtld_isspace(c)	((c) == ' ' || (c) == '\t')
62
63int
64lm_init(char *libmap_override)
65{
66	char *p;
67
68	dbg("lm_init(\"%s\")", libmap_override);
69	TAILQ_INIT(&lmp_head);
70
71	lmc_parse_file(ld_path_libmap_conf);
72
73	if (libmap_override) {
74		/*
75		 * Do some character replacement to make $LDLIBMAP look
76		 * like a text file, then parse it.
77		 */
78		libmap_override = xstrdup(libmap_override);
79		for (p = libmap_override; *p; p++) {
80			switch (*p) {
81			case '=':
82				*p = ' ';
83				break;
84			case ',':
85				*p = '\n';
86				break;
87			}
88		}
89		lmc_parse(libmap_override, p - libmap_override);
90		free(libmap_override);
91	}
92
93	return (lm_count == 0);
94}
95
96static void
97lmc_parse_file(char *path)
98{
99	struct lmc *p;
100	struct stat st;
101	int fd;
102	char *rpath;
103	char *lm_map;
104
105	rpath = realpath(path, NULL);
106	if (rpath == NULL)
107		return;
108
109	TAILQ_FOREACH(p, &lmc_head, next) {
110		if (strcmp(p->path, rpath) == 0) {
111			free(rpath);
112			return;
113		}
114	}
115
116	fd = open(rpath, O_RDONLY | O_CLOEXEC);
117	if (fd == -1) {
118		dbg("lm_parse_file: open(\"%s\") failed, %s", rpath,
119		    rtld_strerror(errno));
120		free(rpath);
121		return;
122	}
123	if (fstat(fd, &st) == -1) {
124		close(fd);
125		dbg("lm_parse_file: fstat(\"%s\") failed, %s", rpath,
126		    rtld_strerror(errno));
127		free(rpath);
128		return;
129	}
130	lm_map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
131	if (lm_map == (const char *)MAP_FAILED) {
132		close(fd);
133		dbg("lm_parse_file: mmap(\"%s\") failed, %s", rpath,
134		    rtld_strerror(errno));
135		free(rpath);
136		return;
137	}
138	close(fd);
139	p = xmalloc(sizeof(struct lmc));
140	p->path = rpath;
141	TAILQ_INSERT_HEAD(&lmc_head, p, next);
142	lmc_parse(lm_map, st.st_size);
143	munmap(lm_map, st.st_size);
144}
145
146static void
147lmc_parse_dir(char *idir)
148{
149	DIR *d;
150	struct dirent *dp;
151	struct lmc *p;
152	char conffile[MAXPATHLEN];
153	char *ext;
154	char *rpath;
155
156	rpath = realpath(idir, NULL);
157	if (rpath == NULL)
158		return;
159
160	TAILQ_FOREACH(p, &lmc_head, next) {
161		if (strcmp(p->path, rpath) == 0) {
162			free(rpath);
163			return;
164		}
165	}
166	d = opendir(idir);
167	if (d == NULL) {
168		free(rpath);
169		return;
170	}
171
172	p = xmalloc(sizeof(struct lmc));
173	p->path = rpath;
174	TAILQ_INSERT_HEAD(&lmc_head, p, next);
175
176	while ((dp = readdir(d)) != NULL) {
177		if (dp->d_ino == 0)
178			continue;
179		if (dp->d_type != DT_REG)
180			continue;
181		ext = strrchr(dp->d_name, '.');
182		if (ext == NULL)
183			continue;
184		if (strcmp(ext, ".conf") != 0)
185			continue;
186		if (strlcpy(conffile, idir, MAXPATHLEN) >= MAXPATHLEN)
187			continue; /* too long */
188		if (strlcat(conffile, "/", MAXPATHLEN) >= MAXPATHLEN)
189			continue; /* too long */
190		if (strlcat(conffile, dp->d_name, MAXPATHLEN) >= MAXPATHLEN)
191			continue; /* too long */
192		lmc_parse_file(conffile);
193	}
194	closedir(d);
195}
196
197static void
198lmc_parse(char *lm_p, size_t lm_len)
199{
200	char *cp, *f, *t, *c, *p;
201	char prog[MAXPATHLEN];
202	/* allow includedir + full length path */
203	char line[MAXPATHLEN + 13];
204	size_t cnt;
205	int i;
206
207	cnt = 0;
208	p = NULL;
209	while (cnt < lm_len) {
210		i = 0;
211		while (cnt < lm_len && lm_p[cnt] != '\n' &&
212		    i < sizeof(line) - 1) {
213			line[i] = lm_p[cnt];
214			cnt++;
215			i++;
216		}
217		line[i] = '\0';
218		while (cnt < lm_len && lm_p[cnt] != '\n')
219			cnt++;
220		/* skip over nl */
221		cnt++;
222
223		cp = &line[0];
224		t = f = c = NULL;
225
226		/* Skip over leading space */
227		while (rtld_isspace(*cp)) cp++;
228
229		/* Found a comment or EOL */
230		if (iseol(*cp)) continue;
231
232		/* Found a constraint selector */
233		if (*cp == '[') {
234			cp++;
235
236			/* Skip leading space */
237			while (rtld_isspace(*cp)) cp++;
238
239			/* Found comment, EOL or end of selector */
240			if  (iseol(*cp) || *cp == ']')
241				continue;
242
243			c = cp++;
244			/* Skip to end of word */
245			while (!rtld_isspace(*cp) && !iseol(*cp) && *cp != ']')
246				cp++;
247
248			/* Skip and zero out trailing space */
249			while (rtld_isspace(*cp)) *cp++ = '\0';
250
251			/* Check if there is a closing brace */
252			if (*cp != ']') continue;
253
254			/* Terminate string if there was no trailing space */
255			*cp++ = '\0';
256
257			/*
258			 * There should be nothing except whitespace or comment
259			  from this point to the end of the line.
260			 */
261			while(rtld_isspace(*cp)) cp++;
262			if (!iseol(*cp)) continue;
263
264			if (strlcpy(prog, c, sizeof prog) >= sizeof prog)
265				continue;
266			p = prog;
267			continue;
268		}
269
270		/* Parse the 'from' candidate. */
271		f = cp++;
272		while (!rtld_isspace(*cp) && !iseol(*cp)) cp++;
273
274		/* Skip and zero out the trailing whitespace */
275		while (rtld_isspace(*cp)) *cp++ = '\0';
276
277		/* Found a comment or EOL */
278		if (iseol(*cp)) continue;
279
280		/* Parse 'to' mapping */
281		t = cp++;
282		while (!rtld_isspace(*cp) && !iseol(*cp)) cp++;
283
284		/* Skip and zero out the trailing whitespace */
285		while (rtld_isspace(*cp)) *cp++ = '\0';
286
287		/* Should be no extra tokens at this point */
288		if (!iseol(*cp)) continue;
289
290		*cp = '\0';
291		if (strcmp(f, "includedir") == 0)
292			lmc_parse_dir(t);
293		else if (strcmp(f, "include") == 0)
294			lmc_parse_file(t);
295		else
296			lm_add(p, f, t);
297	}
298}
299
300static void
301lm_free (struct lm_list *lml)
302{
303	struct lm *lm;
304
305	dbg("%s(%p)", __func__, lml);
306
307	while (!TAILQ_EMPTY(lml)) {
308		lm = TAILQ_FIRST(lml);
309		TAILQ_REMOVE(lml, lm, lm_link);
310		free(lm->f);
311		free(lm->t);
312		free(lm);
313	}
314	return;
315}
316
317void
318lm_fini (void)
319{
320	struct lmp *lmp;
321	struct lmc *p;
322
323	dbg("%s()", __func__);
324
325	while (!TAILQ_EMPTY(&lmc_head)) {
326		p = TAILQ_FIRST(&lmc_head);
327		TAILQ_REMOVE(&lmc_head, p, next);
328		free(p->path);
329		free(p);
330	}
331
332	while (!TAILQ_EMPTY(&lmp_head)) {
333		lmp = TAILQ_FIRST(&lmp_head);
334		TAILQ_REMOVE(&lmp_head, lmp, lmp_link);
335		free(lmp->p);
336		lm_free(&lmp->lml);
337		free(lmp);
338	}
339	return;
340}
341
342static void
343lm_add (const char *p, const char *f, const char *t)
344{
345	struct lm_list *lml;
346	struct lm *lm;
347
348	if (p == NULL)
349		p = "$DEFAULT$";
350
351	dbg("%s(\"%s\", \"%s\", \"%s\")", __func__, p, f, t);
352
353	if ((lml = lmp_find(p)) == NULL)
354		lml = lmp_init(xstrdup(p));
355
356	lm = xmalloc(sizeof(struct lm));
357	lm->f = xstrdup(f);
358	lm->t = xstrdup(t);
359	TAILQ_INSERT_HEAD(lml, lm, lm_link);
360	lm_count++;
361}
362
363char *
364lm_find (const char *p, const char *f)
365{
366	struct lm_list *lml;
367	char *t;
368
369	dbg("%s(\"%s\", \"%s\")", __func__, p, f);
370
371	if (p != NULL && (lml = lmp_find(p)) != NULL) {
372		t = lml_find(lml, f);
373		if (t != NULL) {
374			/*
375			 * Add a global mapping if we have
376			 * a successful constrained match.
377			 */
378			lm_add(NULL, f, t);
379			return (t);
380		}
381	}
382	lml = lmp_find("$DEFAULT$");
383	if (lml != NULL)
384		return (lml_find(lml, f));
385	else
386		return (NULL);
387}
388
389/* Given a libmap translation list and a library name, return the
390   replacement library, or NULL */
391char *
392lm_findn (const char *p, const char *f, const int n)
393{
394	char pathbuf[64], *s, *t;
395
396	if (n < sizeof(pathbuf) - 1)
397		s = pathbuf;
398	else
399		s = xmalloc(n + 1);
400	memcpy(s, f, n);
401	s[n] = '\0';
402	t = lm_find(p, s);
403	if (s != pathbuf)
404		free(s);
405	return (t);
406}
407
408static char *
409lml_find (struct lm_list *lmh, const char *f)
410{
411	struct lm *lm;
412
413	dbg("%s(%p, \"%s\")", __func__, lmh, f);
414
415	TAILQ_FOREACH(lm, lmh, lm_link)
416		if (strcmp(f, lm->f) == 0)
417			return (lm->t);
418	return (NULL);
419}
420
421/* Given an executable name, return a pointer to the translation list or
422   NULL if no matches */
423static struct lm_list *
424lmp_find (const char *n)
425{
426	struct lmp *lmp;
427
428	dbg("%s(\"%s\")", __func__, n);
429
430	TAILQ_FOREACH(lmp, &lmp_head, lmp_link)
431		if ((lmp->type == T_EXACT && strcmp(n, lmp->p) == 0) ||
432		    (lmp->type == T_DIRECTORY && strncmp(n, lmp->p, strlen(lmp->p)) == 0) ||
433		    (lmp->type == T_BASENAME && strcmp(quickbasename(n), lmp->p) == 0))
434			return (&lmp->lml);
435	return (NULL);
436}
437
438static struct lm_list *
439lmp_init (char *n)
440{
441	struct lmp *lmp;
442
443	dbg("%s(\"%s\")", __func__, n);
444
445	lmp = xmalloc(sizeof(struct lmp));
446	lmp->p = n;
447	if (n[strlen(n)-1] == '/')
448		lmp->type = T_DIRECTORY;
449	else if (strchr(n,'/') == NULL)
450		lmp->type = T_BASENAME;
451	else
452		lmp->type = T_EXACT;
453	TAILQ_INIT(&lmp->lml);
454	TAILQ_INSERT_HEAD(&lmp_head, lmp, lmp_link);
455
456	return (&lmp->lml);
457}
458
459/* libc basename is overkill.  Return a pointer to the character after the
460   last /, or the original string if there are no slashes. */
461static const char *
462quickbasename (const char *path)
463{
464	const char *p = path;
465	for (; *path; path++) {
466		if (*path == '/')
467			p = path+1;
468	}
469	return (p);
470}
471