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-rw-r--r--applets/applets.c483
1 files changed, 483 insertions, 0 deletions
diff --git a/applets/applets.c b/applets/applets.c
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1/* vi: set sw=4 ts=4: */
2/*
3 * Utility routines.
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.
8 *
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.
11 *
12 * Licensed under GPLv2 or later, see file License in this tarball for details.
13 */
14
15#include "busybox.h"
16#include <unistd.h>
17#include <string.h>
18#include <assert.h>
19
20/* Apparently uclibc defines __GLIBC__ (compat trick?). Oh well. */
21#if ENABLE_STATIC && defined(__GLIBC__) && !defined(__UCLIBC__)
22#warning Static linking against glibc produces buggy executables
23#warning (glibc does not cope well with ld --gc-sections).
24#warning See sources.redhat.com/bugzilla/show_bug.cgi?id=3400
25#warning Note that glibc is utterly unsuitable for static linking anyway.
26#endif
27
28#if ENABLE_SHOW_USAGE && !ENABLE_FEATURE_COMPRESS_USAGE
29static const char usage_messages[] =
30#define MAKE_USAGE
31#include "usage.h"
32#include "applets.h"
33;
34#undef MAKE_USAGE
35#else
36#define usage_messages 0
37#endif /* ENABLE_SHOW_USAGE */
38
39#undef APPLET
40#undef APPLET_NOUSAGE
41#undef PROTOTYPES
42#include "applets.h"
43
44static struct BB_applet *applet_using;
45
46/* The -1 arises because of the {0,NULL,0,-1} entry above. */
47const size_t NUM_APPLETS = (sizeof (applets) / sizeof (struct BB_applet) - 1);
48
49
50#ifdef CONFIG_FEATURE_SUID_CONFIG
51
52#include <ctype.h>
53
54#define CONFIG_FILE "/etc/busybox.conf"
55
56/* applets [] is const, so we have to define this "override" structure */
57static struct BB_suid_config
58{
59 struct BB_applet *m_applet;
60
61 uid_t m_uid;
62 gid_t m_gid;
63 mode_t m_mode;
64
65 struct BB_suid_config *m_next;
66} *suid_config;
67
68static int suid_cfg_readable;
69
70/* check if u is member of group g */
71static int ingroup(uid_t u, gid_t g)
72{
73 struct group *grp = getgrgid(g);
74
75 if (grp) {
76 char **mem;
77
78 for (mem = grp->gr_mem; *mem; mem++) {
79 struct passwd *pwd = getpwnam(*mem);
80
81 if (pwd && (pwd->pw_uid == u))
82 return 1;
83 }
84 }
85 return 0;
86}
87
88/* This should probably be a libbb routine. In that case,
89 * I'd probably rename it to something like bb_trimmed_slice.
90 */
91static char *get_trimmed_slice(char *s, char *e)
92{
93 /* First, consider the value at e to be nul and back up until we
94 * reach a non-space char. Set the char after that (possibly at
95 * the original e) to nul. */
96 while (e-- > s) {
97 if (!isspace(*e)) {
98 break;
99 }
100 }
101 e[1] = 0;
102
103 /* Next, advance past all leading space and return a ptr to the
104 * first non-space char; possibly the terminating nul. */
105 return skip_whitespace(s);
106}
107
108
109#define parse_error(x) { err=x; goto pe_label; }
110
111/* Don't depend on the tools to combine strings. */
112static const char config_file[] = CONFIG_FILE;
113
114/* There are 4 chars + 1 nul for each of user/group/other. */
115static const char mode_chars[] = "Ssx-\0Ssx-\0Ttx-";
116
117/* We don't supply a value for the nul, so an index adjustment is
118 * necessary below. Also, we use unsigned short here to save some
119 * space even though these are really mode_t values. */
120static const unsigned short mode_mask[] = {
121 /* SST sst xxx --- */
122 S_ISUID, S_ISUID|S_IXUSR, S_IXUSR, 0, /* user */
123 S_ISGID, S_ISGID|S_IXGRP, S_IXGRP, 0, /* group */
124 0, S_IXOTH, S_IXOTH, 0 /* other */
125};
126
127static void parse_config_file(void)
128{
129 struct BB_suid_config *sct_head;
130 struct BB_suid_config *sct;
131 struct BB_applet *applet;
132 FILE *f;
133 char *err;
134 char *s;
135 char *e;
136 int i, lc, section;
137 char buffer[256];
138 struct stat st;
139
140 assert(!suid_config); /* Should be set to NULL by bss init. */
141
142 if ((stat(config_file, &st) != 0) /* No config file? */
143 || !S_ISREG(st.st_mode) /* Not a regular file? */
144 || (st.st_uid != 0) /* Not owned by root? */
145 || (st.st_mode & (S_IWGRP | S_IWOTH)) /* Writable by non-root? */
146 || !(f = fopen(config_file, "r")) /* Cannot open? */
147 ) {
148 return;
149 }
150
151 suid_cfg_readable = 1;
152 sct_head = NULL;
153 section = lc = 0;
154
155 do {
156 s = buffer;
157
158 if (!fgets(s, sizeof(buffer), f)) { /* Are we done? */
159 if (ferror(f)) { /* Make sure it wasn't a read error. */
160 parse_error("reading");
161 }
162 fclose(f);
163 suid_config = sct_head; /* Success, so set the pointer. */
164 return;
165 }
166
167 lc++; /* Got a (partial) line. */
168
169 /* If a line is too long for our buffer, we consider it an error.
170 * The following test does mistreat one corner case though.
171 * If the final line of the file does not end with a newline and
172 * yet exactly fills the buffer, it will be treated as too long
173 * even though there isn't really a problem. But it isn't really
174 * worth adding code to deal with such an unlikely situation, and
175 * we do err on the side of caution. Besides, the line would be
176 * too long if it did end with a newline. */
177 if (!strchr(s, '\n') && !feof(f)) {
178 parse_error("line too long");
179 }
180
181 /* Trim leading and trailing whitespace, ignoring comments, and
182 * check if the resulting string is empty. */
183 if (!*(s = get_trimmed_slice(s, strchrnul(s, '#')))) {
184 continue;
185 }
186
187 /* Check for a section header. */
188
189 if (*s == '[') {
190 /* Unlike the old code, we ignore leading and trailing
191 * whitespace for the section name. We also require that
192 * there are no stray characters after the closing bracket. */
193 if (!(e = strchr(s, ']')) /* Missing right bracket? */
194 || e[1] /* Trailing characters? */
195 || !*(s = get_trimmed_slice(s+1, e)) /* Missing name? */
196 ) {
197 parse_error("section header");
198 }
199 /* Right now we only have one section so just check it.
200 * If more sections are added in the future, please don't
201 * resort to cascading ifs with multiple strcasecmp calls.
202 * That kind of bloated code is all too common. A loop
203 * and a string table would be a better choice unless the
204 * number of sections is very small. */
205 if (strcasecmp(s, "SUID") == 0) {
206 section = 1;
207 continue;
208 }
209 section = -1; /* Unknown section so set to skip. */
210 continue;
211 }
212
213 /* Process sections. */
214
215 if (section == 1) { /* SUID */
216 /* Since we trimmed leading and trailing space above, we're
217 * now looking for strings of the form
218 * <key>[::space::]*=[::space::]*<value>
219 * where both key and value could contain inner whitespace. */
220
221 /* First get the key (an applet name in our case). */
222 if (!!(e = strchr(s, '='))) {
223 s = get_trimmed_slice(s, e);
224 }
225 if (!e || !*s) { /* Missing '=' or empty key. */
226 parse_error("keyword");
227 }
228
229 /* Ok, we have an applet name. Process the rhs if this
230 * applet is currently built in and ignore it otherwise.
231 * Note: This can hide config file bugs which only pop
232 * up when the busybox configuration is changed. */
233 if ((applet = find_applet_by_name(s))) {
234 /* Note: We currently don't check for duplicates!
235 * The last config line for each applet will be the
236 * one used since we insert at the head of the list.
237 * I suppose this could be considered a feature. */
238 sct = xmalloc(sizeof(struct BB_suid_config));
239 sct->m_applet = applet;
240 sct->m_mode = 0;
241 sct->m_next = sct_head;
242 sct_head = sct;
243
244 /* Get the specified mode. */
245
246 e = skip_whitespace(e+1);
247
248 for (i=0 ; i < 3 ; i++) {
249 const char *q;
250 if (!*(q = strchrnul(mode_chars + 5*i, *e++))) {
251 parse_error("mode");
252 }
253 /* Adjust by -i to account for nul. */
254 sct->m_mode |= mode_mask[(q - mode_chars) - i];
255 }
256
257 /* Now get the the user/group info. */
258
259 s = skip_whitespace(e);
260
261 /* Note: We require whitespace between the mode and the
262 * user/group info. */
263 if ((s == e) || !(e = strchr(s, '.'))) {
264 parse_error("<uid>.<gid>");
265 }
266 *e++ = 0;
267
268 /* We can't use get_ug_id here since it would exit()
269 * if a uid or gid was not found. Oh well... */
270 {
271 char *e2;
272
273 sct->m_uid = strtoul(s, &e2, 10);
274 if (*e2 || (s == e2)) {
275 struct passwd *pwd = getpwnam(s);
276 if (!pwd) {
277 parse_error("user");
278 }
279 sct->m_uid = pwd->pw_uid;
280 }
281
282 sct->m_gid = strtoul(e, &e2, 10);
283 if (*e2 || (e == e2)) {
284 struct group *grp;
285 if (!(grp = getgrnam(e))) {
286 parse_error("group");
287 }
288 sct->m_gid = grp->gr_gid;
289 }
290 }
291 }
292 continue;
293 }
294
295 /* Unknown sections are ignored. */
296
297 /* Encountering configuration lines prior to seeing a
298 * section header is treated as an error. This is how
299 * the old code worked, but it may not be desirable.
300 * We may want to simply ignore such lines in case they
301 * are used in some future version of busybox. */
302 if (!section) {
303 parse_error("keyword outside section");
304 }
305
306 } while (1);
307
308 pe_label:
309 fprintf(stderr, "Parse error in %s, line %d: %s\n",
310 config_file, lc, err);
311
312 fclose(f);
313 /* Release any allocated memory before returning. */
314 while (sct_head) {
315 sct = sct_head->m_next;
316 free(sct_head);
317 sct_head = sct;
318 }
319 return;
320}
321
322#else
323#define parse_config_file()
324#endif /* CONFIG_FEATURE_SUID_CONFIG */
325
326#ifdef CONFIG_FEATURE_SUID
327static void check_suid(struct BB_applet *applet)
328{
329 uid_t ruid = getuid(); /* real [ug]id */
330 uid_t rgid = getgid();
331
332#ifdef CONFIG_FEATURE_SUID_CONFIG
333 if (suid_cfg_readable) {
334 struct BB_suid_config *sct;
335
336 for (sct = suid_config; sct; sct = sct->m_next) {
337 if (sct->m_applet == applet)
338 break;
339 }
340 if (sct) {
341 mode_t m = sct->m_mode;
342
343 if (sct->m_uid == ruid) /* same uid */
344 m >>= 6;
345 else if ((sct->m_gid == rgid) || ingroup(ruid, sct->m_gid)) /* same group / in group */
346 m >>= 3;
347
348 if (!(m & S_IXOTH)) /* is x bit not set ? */
349 bb_error_msg_and_die("you have no permission to run this applet!");
350
351 if ((sct->m_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { /* *both* have to be set for sgid */
352 xsetgid(sct->m_gid);
353 } else xsetgid(rgid); /* no sgid -> drop */
354
355 if (sct->m_mode & S_ISUID) xsetuid(sct->m_uid);
356 else xsetuid(ruid); /* no suid -> drop */
357 } else {
358 /* default: drop all privileges */
359 xsetgid(rgid);
360 xsetuid(ruid);
361 }
362 return;
363 } else {
364#ifndef CONFIG_FEATURE_SUID_CONFIG_QUIET
365 static int onetime = 0;
366
367 if (!onetime) {
368 onetime = 1;
369 fprintf(stderr, "Using fallback suid method\n");
370 }
371#endif
372 }
373#endif
374
375 if (applet->need_suid == _BB_SUID_ALWAYS) {
376 if (geteuid()) bb_error_msg_and_die("applet requires root privileges!");
377 } else if (applet->need_suid == _BB_SUID_NEVER) {
378 xsetgid(rgid); /* drop all privileges */
379 xsetuid(ruid);
380 }
381}
382#else
383#define check_suid(x)
384#endif /* CONFIG_FEATURE_SUID */
385
386
387
388#ifdef CONFIG_FEATURE_COMPRESS_USAGE
389
390#include "usage_compressed.h"
391#include "unarchive.h"
392
393static const char *unpack_usage_messages(void)
394{
395 int input[2], output[2], pid;
396 char *buf;
397
398 if(pipe(input) < 0 || pipe(output) < 0)
399 exit(1);
400
401 pid = fork();
402 switch (pid) {
403 case -1: /* error */
404 exit(1);
405 case 0: /* child */
406 close(input[1]);
407 close(output[0]);
408 uncompressStream(input[0], output[1]);
409 exit(0);
410 }
411 /* parent */
412
413 close(input[0]);
414 close(output[1]);
415 pid = fork();
416 switch (pid) {
417 case -1: /* error */
418 exit(1);
419 case 0: /* child */
420 full_write(input[1], packed_usage, sizeof(packed_usage));
421 exit(0);
422 }
423 /* parent */
424 close(input[1]);
425
426 buf = xmalloc(SIZEOF_usage_messages);
427 full_read(output[0], buf, SIZEOF_usage_messages);
428 return buf;
429}
430
431#else
432#define unpack_usage_messages() usage_messages
433#endif /* ENABLE_FEATURE_COMPRESS_USAGE */
434
435void bb_show_usage(void)
436{
437 if (ENABLE_SHOW_USAGE) {
438 const char *format_string;
439 const char *usage_string = unpack_usage_messages();
440 int i;
441
442 for (i = applet_using - applets; i > 0;)
443 if (!*usage_string++) --i;
444
445 format_string = "%s\n\nUsage: %s %s\n\n";
446 if (*usage_string == '\b')
447 format_string = "%s\n\nNo help available.\n\n";
448 fprintf(stderr, format_string, bb_msg_full_version,
449 applet_using->name, usage_string);
450 }
451
452 exit(xfunc_error_retval);
453}
454
455static int applet_name_compare(const void *name, const void *vapplet)
456{
457 const struct BB_applet *applet = vapplet;
458
459 return strcmp(name, applet->name);
460}
461
462extern const size_t NUM_APPLETS;
463
464struct BB_applet *find_applet_by_name(const char *name)
465{
466 return bsearch(name, applets, NUM_APPLETS, sizeof(struct BB_applet),
467 applet_name_compare);
468}
469
470void run_applet_by_name(const char *name, int argc, char **argv)
471{
472 if (ENABLE_FEATURE_SUID_CONFIG) parse_config_file();
473
474 if (!strncmp(name, "busybox", 7)) busybox_main(argc, argv);
475 /* Do a binary search to find the applet entry given the name. */
476 applet_using = find_applet_by_name(name);
477 if (applet_using) {
478 applet_name = applet_using->name;
479 if(argc==2 && !strcmp(argv[1], "--help")) bb_show_usage();
480 if(ENABLE_FEATURE_SUID) check_suid(applet_using);
481 exit((*(applet_using->main))(argc, argv));
482 }
483}