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 * Based in part on code from sash, Copyright (c) 1999 by David I. Bell
10 * Permission has been granted to redistribute this code under the GPL.
12 * Licensed under GPLv2 or later, see file License in this tarball for details.
20 #if ENABLE_SHOW_USAGE && !ENABLE_FEATURE_COMPRESS_USAGE
21 static const char usage_messages[] =
28 #define usage_messages 0
29 #endif /* ENABLE_SHOW_USAGE */
36 static struct BB_applet *applet_using;
38 /* The -1 arises because of the {0,NULL,0,-1} entry above. */
39 const size_t NUM_APPLETS = (sizeof (applets) / sizeof (struct BB_applet) - 1);
42 #ifdef CONFIG_FEATURE_SUID_CONFIG
48 #define CONFIG_FILE "/etc/busybox.conf"
50 /* applets [] is const, so we have to define this "override" structure */
51 static struct BB_suid_config
53 struct BB_applet *m_applet;
59 struct BB_suid_config *m_next;
62 static int suid_cfg_readable;
64 /* check if u is member of group g */
65 static int ingroup (uid_t u, gid_t g)
67 struct group *grp = getgrgid (g);
72 for (mem = grp->gr_mem; *mem; mem++) {
73 struct passwd *pwd = getpwnam (*mem);
75 if (pwd && (pwd->pw_uid == u))
82 /* This should probably be a libbb routine. In that case,
83 * I'd probably rename it to something like bb_trimmed_slice.
85 static char *get_trimmed_slice(char *s, char *e)
87 /* First, consider the value at e to be nul and back up until we
88 * reach a non-space char. Set the char after that (possibly at
89 * the original e) to nul. */
97 /* Next, advance past all leading space and return a ptr to the
98 * first non-space char; possibly the terminating nul. */
99 return skip_whitespace(s);
103 #define parse_error(x) { err=x; goto pe_label; }
105 /* Don't depend on the tools to combine strings. */
106 static const char config_file[] = CONFIG_FILE;
108 /* There are 4 chars + 1 nul for each of user/group/other. */
109 static const char mode_chars[] = "Ssx-\0Ssx-\0Ttx-";
111 /* We don't supply a value for the nul, so an index adjustment is
112 * necessary below. Also, we use unsigned short here to save some
113 * space even though these are really mode_t values. */
114 static const unsigned short mode_mask[] = {
115 /* SST sst xxx --- */
116 S_ISUID, S_ISUID|S_IXUSR, S_IXUSR, 0, /* user */
117 S_ISGID, S_ISGID|S_IXGRP, S_IXGRP, 0, /* group */
118 0, S_IXOTH, S_IXOTH, 0 /* other */
121 static void parse_config_file(void)
123 struct BB_suid_config *sct_head;
124 struct BB_suid_config *sct;
125 struct BB_applet *applet;
134 assert(!suid_config); /* Should be set to NULL by bss init. */
136 if ((stat(config_file, &st) != 0) /* No config file? */
137 || !S_ISREG(st.st_mode) /* Not a regular file? */
138 || (st.st_uid != 0) /* Not owned by root? */
139 || (st.st_mode & (S_IWGRP | S_IWOTH)) /* Writable by non-root? */
140 || !(f = fopen(config_file, "r")) /* Can not open? */
145 suid_cfg_readable = 1;
152 if (!fgets(s, sizeof(buffer), f)) { /* Are we done? */
153 if (ferror(f)) { /* Make sure it wasn't a read error. */
154 parse_error("reading");
157 suid_config = sct_head; /* Success, so set the pointer. */
161 lc++; /* Got a (partial) line. */
163 /* If a line is too long for our buffer, we consider it an error.
164 * The following test does mistreat one corner case though.
165 * If the final line of the file does not end with a newline and
166 * yet exactly fills the buffer, it will be treated as too long
167 * even though there isn't really a problem. But it isn't really
168 * worth adding code to deal with such an unlikely situation, and
169 * we do err on the side of caution. Besides, the line would be
170 * too long if it did end with a newline. */
171 if (!strchr(s, '\n') && !feof(f)) {
172 parse_error("line too long");
175 /* Trim leading and trailing whitespace, ignoring comments, and
176 * check if the resulting string is empty. */
177 if (!*(s = get_trimmed_slice(s, strchrnul(s, '#')))) {
181 /* Check for a section header. */
184 /* Unlike the old code, we ignore leading and trailing
185 * whitespace for the section name. We also require that
186 * there are no stray characters after the closing bracket. */
187 if (!(e = strchr(s, ']')) /* Missing right bracket? */
188 || e[1] /* Trailing characters? */
189 || !*(s = get_trimmed_slice(s+1, e)) /* Missing name? */
191 parse_error("section header");
193 /* Right now we only have one section so just check it.
194 * If more sections are added in the future, please don't
195 * resort to cascading ifs with multiple strcasecmp calls.
196 * That kind of bloated code is all too common. A loop
197 * and a string table would be a better choice unless the
198 * number of sections is very small. */
199 if (strcasecmp(s, "SUID") == 0) {
203 section = -1; /* Unknown section so set to skip. */
207 /* Process sections. */
209 if (section == 1) { /* SUID */
210 /* Since we trimmed leading and trailing space above, we're
211 * now looking for strings of the form
212 * <key>[::space::]*=[::space::]*<value>
213 * where both key and value could contain inner whitespace. */
215 /* First get the key (an applet name in our case). */
216 if (!!(e = strchr(s, '='))) {
217 s = get_trimmed_slice(s, e);
219 if (!e || !*s) { /* Missing '=' or empty key. */
220 parse_error("keyword");
223 /* Ok, we have an applet name. Process the rhs if this
224 * applet is currently built in and ignore it otherwise.
225 * Note: This can hide config file bugs which only pop
226 * up when the busybox configuration is changed. */
227 if ((applet = find_applet_by_name(s))) {
228 /* Note: We currently don't check for duplicates!
229 * The last config line for each applet will be the
230 * one used since we insert at the head of the list.
231 * I suppose this could be considered a feature. */
232 sct = xmalloc(sizeof(struct BB_suid_config));
233 sct->m_applet = applet;
235 sct->m_next = sct_head;
238 /* Get the specified mode. */
240 e = skip_whitespace(e+1);
242 for (i=0 ; i < 3 ; i++) {
244 if (!*(q = strchrnul(mode_chars + 5*i, *e++))) {
247 /* Adjust by -i to account for nul. */
248 sct->m_mode |= mode_mask[(q - mode_chars) - i];
251 /* Now get the the user/group info. */
253 s = skip_whitespace(e);
255 /* Note: We require whitespace between the mode and the
256 * user/group info. */
257 if ((s == e) || !(e = strchr(s, '.'))) {
258 parse_error("<uid>.<gid>");
262 /* We can't use get_ug_id here since it would exit()
263 * if a uid or gid was not found. Oh well... */
267 sct->m_uid = strtoul(s, &e2, 10);
268 if (*e2 || (s == e2)) {
270 if (!(pwd = getpwnam(s))) {
273 sct->m_uid = pwd->pw_uid;
276 sct->m_gid = strtoul(e, &e2, 10);
277 if (*e2 || (e == e2)) {
279 if (!(grp = getgrnam(e))) {
280 parse_error("group");
282 sct->m_gid = grp->gr_gid;
289 /* Unknown sections are ignored. */
291 /* Encountering configuration lines prior to seeing a
292 * section header is treated as an error. This is how
293 * the old code worked, but it may not be desirable.
294 * We may want to simply ignore such lines in case they
295 * are used in some future version of busybox. */
297 parse_error("keyword outside section");
303 fprintf(stderr, "Parse error in %s, line %d: %s\n",
304 config_file, lc, err);
307 /* Release any allocated memory before returning. */
309 sct = sct_head->m_next;
317 #define parse_config_file()
318 #endif /* CONFIG_FEATURE_SUID_CONFIG */
320 #ifdef CONFIG_FEATURE_SUID
321 static void check_suid (struct BB_applet *applet)
323 uid_t ruid = getuid (); /* real [ug]id */
324 uid_t rgid = getgid ();
326 #ifdef CONFIG_FEATURE_SUID_CONFIG
327 if (suid_cfg_readable) {
328 struct BB_suid_config *sct;
330 for (sct = suid_config; sct; sct = sct->m_next) {
331 if (sct->m_applet == applet)
335 mode_t m = sct->m_mode;
337 if (sct->m_uid == ruid) /* same uid */
339 else if ((sct->m_gid == rgid) || ingroup (ruid, sct->m_gid)) /* same group / in group */
342 if (!(m & S_IXOTH)) /* is x bit not set ? */
343 bb_error_msg_and_die ("You have no permission to run this applet!");
345 if ((sct->m_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { /* *both* have to be set for sgid */
347 } else xsetgid(rgid); /* no sgid -> drop */
349 if (sct->m_mode & S_ISUID) xsetuid(sct->m_uid);
350 else xsetuid(ruid); /* no suid -> drop */
352 /* default: drop all privileges */
358 #ifndef CONFIG_FEATURE_SUID_CONFIG_QUIET
359 static int onetime = 0;
363 fprintf (stderr, "Using fallback suid method\n");
369 if (applet->need_suid == _BB_SUID_ALWAYS) {
370 if (geteuid()) bb_error_msg_and_die("Applet requires root privileges!");
371 } else if (applet->need_suid == _BB_SUID_NEVER) {
372 xsetgid(rgid); /* drop all privileges */
377 #define check_suid(x)
378 #endif /* CONFIG_FEATURE_SUID */
382 #if ENABLE_FEATURE_COMPRESS_USAGE
384 #include "usage_compressed.h"
385 #include "unarchive.h"
387 static const char *unpack_usage_messages(void)
389 int input[2], output[2], pid;
392 if(pipe(input) < 0 || pipe(output) < 0)
402 uncompressStream(input[0], output[1]);
414 full_write(input[1], packed_usage, sizeof(packed_usage));
420 buf = xmalloc(SIZEOF_usage_messages);
421 full_read(output[0], buf, SIZEOF_usage_messages);
426 #define unpack_usage_messages() usage_messages
427 #endif /* ENABLE_FEATURE_COMPRESS_USAGE */
429 void bb_show_usage (void)
431 if (ENABLE_SHOW_USAGE) {
432 const char *format_string;
433 const char *usage_string = unpack_usage_messages();
436 for (i = applet_using - applets; i > 0;)
437 if (!*usage_string++) --i;
439 format_string = "%s\n\nUsage: %s %s\n\n";
440 if (*usage_string == '\b')
441 format_string = "%s\n\nNo help available.\n\n";
442 fprintf (stderr, format_string, bb_msg_full_version,
443 applet_using->name, usage_string);
446 exit (bb_default_error_retval);
449 static int applet_name_compare(const void *name, const void *vapplet)
451 const struct BB_applet *applet = vapplet;
453 return strcmp(name, applet->name);
456 extern const size_t NUM_APPLETS;
458 struct BB_applet *find_applet_by_name(const char *name)
460 return bsearch(name, applets, NUM_APPLETS, sizeof(struct BB_applet),
461 applet_name_compare);
464 void run_applet_by_name(const char *name, int argc, char **argv)
466 if (ENABLE_FEATURE_SUID_CONFIG) parse_config_file();
468 if (!strncmp(name, "busybox", 7)) busybox_main(argc, argv);
469 /* Do a binary search to find the applet entry given the name. */
470 applet_using = find_applet_by_name(name);
472 bb_applet_name = applet_using->name;
473 if(argc==2 && !strcmp(argv[1], "--help")) bb_show_usage();
474 if(ENABLE_FEATURE_SUID) check_suid(applet_using);
475 exit((*(applet_using->main))(argc, argv));