1 /* vi: set sw=4 ts=4: */
5 * Copyright (C) tons of folks. Tracking down who wrote what
6 * isn't something I'm going to worry about... If you wrote something
7 * here, please feel free to acknowledge your work.
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * General Public License for more details.
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 * Based in part on code from sash, Copyright (c) 1999 by David I. Bell
24 * Permission has been granted to redistribute this code under the GPL.
36 const char usage_messages[] =
46 #endif /* ENABLE_SHOW_USAGE */
53 static struct BB_applet *applet_using;
55 /* The -1 arises because of the {0,NULL,0,-1} entry above. */
56 const size_t NUM_APPLETS = (sizeof (applets) / sizeof (struct BB_applet) - 1);
59 #ifdef CONFIG_FEATURE_SUID_CONFIG
66 #define CONFIG_FILE "/etc/busybox.conf"
68 /* applets [] is const, so we have to define this "override" structure */
69 static struct BB_suid_config
71 struct BB_applet *m_applet;
77 struct BB_suid_config *m_next;
80 static int suid_cfg_readable;
82 /* check if u is member of group g */
83 static int ingroup (uid_t u, gid_t g)
85 struct group *grp = getgrgid (g);
90 for (mem = grp->gr_mem; *mem; mem++) {
91 struct passwd *pwd = getpwnam (*mem);
93 if (pwd && (pwd->pw_uid == u))
100 /* This should probably be a libbb routine. In that case,
101 * I'd probably rename it to something like bb_trimmed_slice.
103 static char *get_trimmed_slice(char *s, char *e)
105 /* First, consider the value at e to be nul and back up until we
106 * reach a non-space char. Set the char after that (possibly at
107 * the original e) to nul. */
115 /* Next, advance past all leading space and return a ptr to the
116 * first non-space char; possibly the terminating nul. */
117 return (char *) bb_skip_whitespace(s);
121 #define parse_error(x) { err=x; goto pe_label; }
123 /* Don't depend on the tools to combine strings. */
124 static const char config_file[] = CONFIG_FILE;
126 /* There are 4 chars + 1 nul for each of user/group/other. */
127 static const char mode_chars[] = "Ssx-\0Ssx-\0Ttx-";
129 /* We don't supply a value for the nul, so an index adjustment is
130 * necessary below. Also, we use unsigned short here to save some
131 * space even though these are really mode_t values. */
132 static const unsigned short mode_mask[] = {
133 /* SST sst xxx --- */
134 S_ISUID, S_ISUID|S_IXUSR, S_IXUSR, 0, /* user */
135 S_ISGID, S_ISGID|S_IXGRP, S_IXGRP, 0, /* group */
136 0, S_IXOTH, S_IXOTH, 0 /* other */
139 static void parse_config_file(void)
141 struct BB_suid_config *sct_head;
142 struct BB_suid_config *sct;
143 struct BB_applet *applet;
152 assert(!suid_config); /* Should be set to NULL by bss init. */
154 if ((stat(config_file, &st) != 0) /* No config file? */
155 || !S_ISREG(st.st_mode) /* Not a regular file? */
156 || (st.st_uid != 0) /* Not owned by root? */
157 || (st.st_mode & (S_IWGRP | S_IWOTH)) /* Writable by non-root? */
158 || !(f = fopen(config_file, "r")) /* Can not open? */
163 suid_cfg_readable = 1;
170 if (!fgets(s, sizeof(buffer), f)) { /* Are we done? */
171 if (ferror(f)) { /* Make sure it wasn't a read error. */
172 parse_error("reading");
175 suid_config = sct_head; /* Success, so set the pointer. */
179 lc++; /* Got a (partial) line. */
181 /* If a line is too long for our buffer, we consider it an error.
182 * The following test does mistreat one corner case though.
183 * If the final line of the file does not end with a newline and
184 * yet exactly fills the buffer, it will be treated as too long
185 * even though there isn't really a problem. But it isn't really
186 * worth adding code to deal with such an unlikely situation, and
187 * we do err on the side of caution. Besides, the line would be
188 * too long if it did end with a newline. */
189 if (!strchr(s, '\n') && !feof(f)) {
190 parse_error("line too long");
193 /* Trim leading and trailing whitespace, ignoring comments, and
194 * check if the resulting string is empty. */
195 if (!*(s = get_trimmed_slice(s, strchrnul(s, '#')))) {
199 /* Check for a section header. */
202 /* Unlike the old code, we ignore leading and trailing
203 * whitespace for the section name. We also require that
204 * there are no stray characters after the closing bracket. */
205 if (!(e = strchr(s, ']')) /* Missing right bracket? */
206 || e[1] /* Trailing characters? */
207 || !*(s = get_trimmed_slice(s+1, e)) /* Missing name? */
209 parse_error("section header");
211 /* Right now we only have one section so just check it.
212 * If more sections are added in the future, please don't
213 * resort to cascading ifs with multiple strcasecmp calls.
214 * That kind of bloated code is all too common. A loop
215 * and a string table would be a better choice unless the
216 * number of sections is very small. */
217 if (strcasecmp(s, "SUID") == 0) {
221 section = -1; /* Unknown section so set to skip. */
225 /* Process sections. */
227 if (section == 1) { /* SUID */
228 /* Since we trimmed leading and trailing space above, we're
229 * now looking for strings of the form
230 * <key>[::space::]*=[::space::]*<value>
231 * where both key and value could contain inner whitespace. */
233 /* First get the key (an applet name in our case). */
234 if (!!(e = strchr(s, '='))) {
235 s = get_trimmed_slice(s, e);
237 if (!e || !*s) { /* Missing '=' or empty key. */
238 parse_error("keyword");
241 /* Ok, we have an applet name. Process the rhs if this
242 * applet is currently built in and ignore it otherwise.
243 * Note: This can hide config file bugs which only pop
244 * up when the busybox configuration is changed. */
245 if ((applet = find_applet_by_name(s))) {
246 /* Note: We currently don't check for duplicates!
247 * The last config line for each applet will be the
248 * one used since we insert at the head of the list.
249 * I suppose this could be considered a feature. */
250 sct = xmalloc(sizeof(struct BB_suid_config));
251 sct->m_applet = applet;
253 sct->m_next = sct_head;
256 /* Get the specified mode. */
258 e = (char *) bb_skip_whitespace(e+1);
260 for (i=0 ; i < 3 ; i++) {
262 if (!*(q = strchrnul(mode_chars + 5*i, *e++))) {
265 /* Adjust by -i to account for nul. */
266 sct->m_mode |= mode_mask[(q - mode_chars) - i];
269 /* Now get the the user/group info. */
271 s = (char *) bb_skip_whitespace(e);
273 /* Note: We require whitespace between the mode and the
274 * user/group info. */
275 if ((s == e) || !(e = strchr(s, '.'))) {
276 parse_error("<uid>.<gid>");
280 /* We can't use get_ug_id here since it would exit()
281 * if a uid or gid was not found. Oh well... */
285 sct->m_uid = strtoul(s, &e2, 10);
286 if (*e2 || (s == e2)) {
288 if (!(pwd = getpwnam(s))) {
291 sct->m_uid = pwd->pw_uid;
294 sct->m_gid = strtoul(e, &e2, 10);
295 if (*e2 || (e == e2)) {
297 if (!(grp = getgrnam(e))) {
298 parse_error("group");
300 sct->m_gid = grp->gr_gid;
307 /* Unknown sections are ignored. */
309 /* Encountering configuration lines prior to seeing a
310 * section header is treated as an error. This is how
311 * the old code worked, but it may not be desirable.
312 * We may want to simply ignore such lines in case they
313 * are used in some future version of busybox. */
315 parse_error("keyword outside section");
321 fprintf(stderr, "Parse error in %s, line %d: %s\n",
322 config_file, lc, err);
325 /* Release any allocated memory before returning. */
327 sct = sct_head->m_next;
335 #define parse_config_file()
336 #endif /* CONFIG_FEATURE_SUID_CONFIG */
338 #ifdef CONFIG_FEATURE_SUID
339 static void check_suid (struct BB_applet *applet)
341 uid_t ruid = getuid (); /* real [ug]id */
342 uid_t rgid = getgid ();
344 #ifdef CONFIG_FEATURE_SUID_CONFIG
345 if (suid_cfg_readable) {
346 struct BB_suid_config *sct;
348 for (sct = suid_config; sct; sct = sct->m_next) {
349 if (sct->m_applet == applet)
353 mode_t m = sct->m_mode;
355 if (sct->m_uid == ruid) /* same uid */
357 else if ((sct->m_gid == rgid) || ingroup (ruid, sct->m_gid)) /* same group / in group */
360 if (!(m & S_IXOTH)) /* is x bit not set ? */
361 bb_error_msg_and_die ("You have no permission to run this applet!");
363 if ((sct->m_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { /* *both* have to be set for sgid */
364 if (setegid (sct->m_gid))
366 ("BusyBox binary has insufficient rights to set proper GID for applet!");
368 setgid (rgid); /* no sgid -> drop */
370 if (sct->m_mode & S_ISUID) {
371 if (seteuid (sct->m_uid))
373 ("BusyBox binary has insufficient rights to set proper UID for applet!");
375 setuid (ruid); /* no suid -> drop */
377 /* default: drop all privileges */
383 #ifndef CONFIG_FEATURE_SUID_CONFIG_QUIET
384 static int onetime = 0;
388 fprintf (stderr, "Using fallback suid method\n");
394 if (applet->need_suid == _BB_SUID_ALWAYS) {
396 bb_error_msg_and_die ("This applet requires root privileges!");
397 } else if (applet->need_suid == _BB_SUID_NEVER) {
398 setgid (rgid); /* drop all privileges */
403 #define check_suid(x)
404 #endif /* CONFIG_FEATURE_SUID */
410 void bb_show_usage (void)
412 #if ENABLE_SHOW_USAGE
413 const char *format_string;
414 const char *usage_string = usage_messages;
417 for (i = applet_using - applets; i > 0;) {
418 if (!*usage_string++) {
423 format_string = "%s\n\nUsage: %s %s\n\n";
424 if (*usage_string == '\b')
425 format_string = "%s\n\nNo help available.\n\n";
426 fprintf (stderr, format_string, bb_msg_full_version, applet_using->name,
428 #endif /* ENABLE_SHOW_USAGE */
430 exit (bb_default_error_retval);
433 static int applet_name_compare (const void *x, const void *y)
435 const char *name = x;
436 const struct BB_applet *applet = y;
438 return strcmp (name, applet->name);
441 extern const size_t NUM_APPLETS;
443 struct BB_applet *find_applet_by_name (const char *name)
445 return bsearch (name, applets, NUM_APPLETS, sizeof (struct BB_applet),
446 applet_name_compare);
449 void run_applet_by_name (const char *name, int argc, char **argv)
451 if(ENABLE_FEATURE_SUID_CONFIG) parse_config_file ();
453 if(!strncmp(name, "busybox", 7)) busybox_main(argc, argv);
454 /* Do a binary search to find the applet entry given the name. */
455 applet_using = find_applet_by_name(name);
457 bb_applet_name = applet_using->name;
458 if(argc==2 && !strcmp(argv[1], "--help")) bb_show_usage ();
459 if(ENABLE_FEATURE_SUID) check_suid (applet_using);
460 exit ((*(applet_using->main)) (argc, argv));
468 c-file-style: "linux"