xref: /freebsd/sbin/ldconfig/elfhints.c (revision 643dcf40ee22ff8776918913e2c7ff6c9c0c4be8)
1 /*-
2  * Copyright (c) 1998 John D. Polstra
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  *
26  * $FreeBSD$
27  */
28 
29 #include <sys/param.h>
30 #include <sys/mman.h>
31 #include <sys/stat.h>
32 
33 #include <ctype.h>
34 #include <dirent.h>
35 #include <elf.h>
36 #include <err.h>
37 #include <errno.h>
38 #include <fcntl.h>
39 #include <stdio.h>
40 #include <stdlib.h>
41 #include <string.h>
42 #include <unistd.h>
43 
44 #include "ldconfig.h"
45 
46 #define MAXDIRS		1024		/* Maximum directories in path */
47 #define MAXFILESIZE	(16*1024)	/* Maximum hints file size */
48 
49 static void	add_dir(const char *, const char *, int);
50 static void	read_dirs_from_file(const char *, const char *);
51 static void	read_elf_hints(const char *, int);
52 static void	write_elf_hints(const char *);
53 
54 static const char	*dirs[MAXDIRS];
55 static int		 ndirs;
56 
57 static void
58 add_dir(const char *hintsfile, const char *name, int trusted)
59 {
60 	struct stat 	stbuf;
61 	int		i;
62 
63 	/* Do some security checks */
64 	if (!trusted && !insecure) {
65 		if (stat(name, &stbuf) == -1) {
66 			warn("%s", name);
67 			return;
68 		}
69 		if (stbuf.st_uid != 0) {
70 			warnx("%s: ignoring directory not owned by root", name);
71 			return;
72 		}
73 		if ((stbuf.st_mode & S_IWOTH) != 0) {
74 			warnx("%s: ignoring world-writable directory", name);
75 			return;
76 		}
77 	}
78 
79 	for (i = 0;  i < ndirs;  i++)
80 		if (strcmp(dirs[i], name) == 0)
81 			return;
82 	if (ndirs >= MAXDIRS)
83 		errx(1, "\"%s\": Too many directories in path", hintsfile);
84 	dirs[ndirs++] = name;
85 }
86 
87 void
88 list_elf_hints(const char *hintsfile)
89 {
90 	int	i;
91 	int	nlibs;
92 
93 	read_elf_hints(hintsfile, 1);
94 	printf("%s:\n", hintsfile);
95 	printf("\tsearch directories:");
96 	for (i = 0;  i < ndirs;  i++)
97 		printf("%c%s", i == 0 ? ' ' : ':', dirs[i]);
98 	printf("\n");
99 
100 	nlibs = 0;
101 	for (i = 0;  i < ndirs;  i++) {
102 		DIR		*dirp;
103 		struct dirent	*dp;
104 
105 		if ((dirp = opendir(dirs[i])) == NULL)
106 			continue;
107 		while ((dp = readdir(dirp)) != NULL) {
108 			int		 len;
109 			int		 namelen;
110 			const char	*name;
111 			const char	*vers;
112 
113 			/* Name can't be shorter than "libx.so.0" */
114 			if ((len = strlen(dp->d_name)) < 9 ||
115 			    strncmp(dp->d_name, "lib", 3) != 0)
116 				continue;
117 			name = dp->d_name + 3;
118 			vers = dp->d_name + len;
119 			while (vers > dp->d_name && isdigit(*(vers-1)))
120 				vers--;
121 			if (vers == dp->d_name + len)
122 				continue;
123 			if (vers < dp->d_name + 4 ||
124 			    strncmp(vers - 4, ".so.", 4) != 0)
125 				continue;
126 
127 			/* We have a valid shared library name. */
128 			namelen = (vers - 4) - name;
129 			printf("\t%d:-l%.*s.%s => %s/%s\n", nlibs,
130 			    namelen, name, vers, dirs[i], dp->d_name);
131 			nlibs++;
132 		}
133 		closedir(dirp);
134 	}
135 }
136 
137 static void
138 read_dirs_from_file(const char *hintsfile, const char *listfile)
139 {
140 	FILE	*fp;
141 	char	 buf[MAXPATHLEN];
142 	int	 linenum;
143 
144 	if ((fp = fopen(listfile, "r")) == NULL)
145 		err(1, "%s", listfile);
146 
147 	linenum = 0;
148 	while (fgets(buf, sizeof buf, fp) != NULL) {
149 		char	*cp, *sp;
150 
151 		linenum++;
152 		cp = buf;
153 		/* Skip leading white space. */
154 		while (isspace(*cp))
155 			cp++;
156 		if (*cp == '#' || *cp == '\0')
157 			continue;
158 		sp = cp;
159 		/* Advance over the directory name. */
160 		while (!isspace(*cp) && *cp != '\0')
161 			cp++;
162 		/* Terminate the string and skip trailing white space. */
163 		if (*cp != '\0') {
164 			*cp++ = '\0';
165 			while (isspace(*cp))
166 				cp++;
167 		}
168 		/* Now we had better be at the end of the line. */
169 		if (*cp != '\0')
170 			warnx("%s:%d: trailing characters ignored",
171 			    listfile, linenum);
172 
173 		if ((sp = strdup(sp)) == NULL)
174 			errx(1, "Out of memory");
175 		add_dir(hintsfile, sp, 0);
176 	}
177 
178 	fclose(fp);
179 }
180 
181 static void
182 read_elf_hints(const char *hintsfile, int must_exist)
183 {
184 	int	 		 fd;
185 	struct stat		 s;
186 	void			*mapbase;
187 	struct elfhints_hdr	*hdr;
188 	char			*strtab;
189 	char			*dirlist;
190 	char			*p;
191 
192 	if ((fd = open(hintsfile, O_RDONLY)) == -1) {
193 		if (errno == ENOENT && !must_exist)
194 			return;
195 		err(1, "Cannot open \"%s\"", hintsfile);
196 	}
197 	if (fstat(fd, &s) == -1)
198 		err(1, "Cannot stat \"%s\"", hintsfile);
199 	if (s.st_size > MAXFILESIZE)
200 		errx(1, "\"%s\" is unreasonably large", hintsfile);
201 	/*
202 	 * We use a read-write, private mapping so that we can null-terminate
203 	 * some strings in it without affecting the underlying file.
204 	 */
205 	mapbase = mmap(NULL, s.st_size, PROT_READ|PROT_WRITE,
206 	    MAP_PRIVATE, fd, 0);
207 	if (mapbase == MAP_FAILED)
208 		err(1, "Cannot mmap \"%s\"", hintsfile);
209 	close(fd);
210 
211 	hdr = (struct elfhints_hdr *)mapbase;
212 	if (hdr->magic != ELFHINTS_MAGIC)
213 		errx(1, "\"%s\": invalid file format", hintsfile);
214 	if (hdr->version != 1)
215 		errx(1, "\"%s\": unrecognized file version (%d)", hintsfile,
216 		    hdr->version);
217 
218 	strtab = (char *)mapbase + hdr->strtab;
219 	dirlist = strtab + hdr->dirlist;
220 
221 	if (*dirlist != '\0')
222 		while ((p = strsep(&dirlist, ":")) != NULL)
223 			add_dir(hintsfile, p, 1);
224 }
225 
226 void
227 update_elf_hints(const char *hintsfile, int argc, char **argv, int merge)
228 {
229 	int	i;
230 
231 	if (merge)
232 		read_elf_hints(hintsfile, 0);
233 	for (i = 0;  i < argc;  i++) {
234 		struct stat	s;
235 
236 		if (stat(argv[i], &s) == -1)
237 			warn("warning: %s", argv[i]);
238 		else if (S_ISREG(s.st_mode))
239 			read_dirs_from_file(hintsfile, argv[i]);
240 		else
241 			add_dir(hintsfile, argv[i], 0);
242 	}
243 	write_elf_hints(hintsfile);
244 }
245 
246 static void
247 write_elf_hints(const char *hintsfile)
248 {
249 	struct elfhints_hdr	 hdr;
250 	char			*tempname;
251 	int			 fd;
252 	FILE			*fp;
253 	int			 i;
254 
255 	if (asprintf(&tempname, "%s.XXXXXX", hintsfile) == -1)
256 		errx(1, "Out of memory");
257 	if ((fd = mkstemp(tempname)) ==  -1)
258 		err(1, "mkstemp(%s)", tempname);
259 	if (fchmod(fd, 0444) == -1)
260 		err(1, "fchmod(%s)", tempname);
261 	if ((fp = fdopen(fd, "wb")) == NULL)
262 		err(1, "fdopen(%s)", tempname);
263 
264 	hdr.magic = ELFHINTS_MAGIC;
265 	hdr.version = 1;
266 	hdr.strtab = sizeof hdr;
267 	hdr.strsize = 0;
268 	hdr.dirlist = 0;
269 	memset(hdr.spare, 0, sizeof hdr.spare);
270 
271 	/* Count up the size of the string table. */
272 	if (ndirs > 0) {
273 		hdr.strsize += strlen(dirs[0]);
274 		for (i = 1;  i < ndirs;  i++)
275 			hdr.strsize += 1 + strlen(dirs[i]);
276 	}
277 	hdr.dirlistlen = hdr.strsize;
278 	hdr.strsize++;	/* For the null terminator */
279 
280 	/* Write the header. */
281 	if (fwrite(&hdr, 1, sizeof hdr, fp) != sizeof hdr)
282 		err(1, "%s: write error", tempname);
283 	/* Write the strings. */
284 	if (ndirs > 0) {
285 		if (fputs(dirs[0], fp) == EOF)
286 			err(1, "%s: write error", tempname);
287 		for (i = 1;  i < ndirs;  i++)
288 			if (fprintf(fp, ":%s", dirs[i]) < 0)
289 				err(1, "%s: write error", tempname);
290 	}
291 	if (putc('\0', fp) == EOF || fclose(fp) == EOF)
292 		err(1, "%s: write error", tempname);
293 
294 	if (rename(tempname, hintsfile) == -1)
295 		err(1, "rename %s to %s", tempname, hintsfile);
296 	free(tempname);
297 }
298