source: MondoRescue/branches/stable/mindi-busybox/applets/applets.c @ 821

Last change on this file since 821 was 821, checked in by Bruno Cornec, 14 years ago

Addition of busybox 1.2.1 as a mindi-busybox new package
This should avoid delivering binary files in mindi not built there (Fedora and Debian are quite serious about that)

File size: 12.5 KB
Line 
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#if ENABLE_SHOW_USAGE && !ENABLE_FEATURE_COMPRESS_USAGE
21static const char usage_messages[] =
22#define MAKE_USAGE
23#include "usage.h"
24#include "applets.h"
25;
26#undef MAKE_USAGE
27#else
28#define usage_messages 0
29#endif /* ENABLE_SHOW_USAGE */
30
31#undef APPLET
32#undef APPLET_NOUSAGE
33#undef PROTOTYPES
34#include "applets.h"
35
36static struct BB_applet *applet_using;
37
38/* The -1 arises because of the {0,NULL,0,-1} entry above. */
39const size_t NUM_APPLETS = (sizeof (applets) / sizeof (struct BB_applet) - 1);
40
41
42#ifdef CONFIG_FEATURE_SUID_CONFIG
43
44#include <ctype.h>
45#include "pwd_.h"
46#include "grp_.h"
47
48#define CONFIG_FILE "/etc/busybox.conf"
49
50/* applets [] is const, so we have to define this "override" structure */
51static struct BB_suid_config
52{
53  struct BB_applet *m_applet;
54
55  uid_t m_uid;
56  gid_t m_gid;
57  mode_t m_mode;
58
59  struct BB_suid_config *m_next;
60} *suid_config;
61
62static int suid_cfg_readable;
63
64/* check if u is member of group g */
65static int ingroup (uid_t u, gid_t g)
66{
67  struct group *grp = getgrgid (g);
68
69  if (grp) {
70    char **mem;
71
72    for (mem = grp->gr_mem; *mem; mem++) {
73      struct passwd *pwd = getpwnam (*mem);
74
75      if (pwd && (pwd->pw_uid == u))
76        return 1;
77    }
78  }
79  return 0;
80}
81
82/* This should probably be a libbb routine.  In that case,
83 * I'd probably rename it to something like bb_trimmed_slice.
84 */
85static char *get_trimmed_slice(char *s, char *e)
86{
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. */
90    while (e-- > s) {
91        if (!isspace(*e)) {
92            break;
93        }
94    }
95    e[1] = 0;
96
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);
100}
101
102
103#define parse_error(x)  { err=x; goto pe_label; }
104
105/* Don't depend on the tools to combine strings. */
106static const char config_file[] = CONFIG_FILE;
107
108/* There are 4 chars + 1 nul for each of user/group/other. */
109static const char mode_chars[] = "Ssx-\0Ssx-\0Ttx-";
110
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. */
114static 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 */
119};
120
121static void parse_config_file(void)
122{
123    struct BB_suid_config *sct_head;
124    struct BB_suid_config *sct;
125    struct BB_applet *applet;
126    FILE *f;
127    char *err;
128    char *s;
129    char *e;
130    int i, lc, section;
131    char buffer[256];
132    struct stat st;
133
134    assert(!suid_config);       /* Should be set to NULL by bss init. */
135
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? */
141        ) {
142        return;
143    }
144
145    suid_cfg_readable = 1;
146    sct_head = NULL;
147    section = lc = 0;
148
149    do {
150        s = buffer;
151
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");
155            }
156            fclose(f);
157            suid_config = sct_head; /* Success, so set the pointer. */
158            return;
159        }
160
161        lc++;                   /* Got a (partial) line. */
162
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");
173        }
174
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, '#')))) {
178            continue;
179        }
180
181        /* Check for a section header. */
182
183        if (*s == '[') {
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? */
190                ) {
191                parse_error("section header");
192            }
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) {
200                section = 1;
201                continue;
202            }
203            section = -1;   /* Unknown section so set to skip. */
204            continue;
205        }
206
207        /* Process sections. */
208
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. */
214
215            /* First get the key (an applet name in our case). */
216            if (!!(e = strchr(s, '='))) {
217                s = get_trimmed_slice(s, e);
218            }
219            if (!e || !*s) {    /* Missing '=' or empty key. */
220                parse_error("keyword");
221            }
222
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;
234                sct->m_mode = 0;
235                sct->m_next = sct_head;
236                sct_head = sct;
237
238                /* Get the specified mode. */
239
240                e = skip_whitespace(e+1);
241
242                for (i=0 ; i < 3 ; i++) {
243                    const char *q;
244                    if (!*(q = strchrnul(mode_chars + 5*i, *e++))) {
245                        parse_error("mode");
246                    }
247                    /* Adjust by -i to account for nul. */
248                    sct->m_mode |= mode_mask[(q - mode_chars) - i];
249                }
250
251                /* Now get the the user/group info. */
252
253                s = skip_whitespace(e);
254
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>");
259                }
260                *e++ = 0;
261
262                /* We can't use get_ug_id here since it would exit()
263                 * if a uid or gid was not found.  Oh well... */
264                {
265                    char *e2;
266
267                    sct->m_uid = strtoul(s, &e2, 10);
268                    if (*e2 || (s == e2)) {
269                        struct passwd *pwd;
270                        if (!(pwd = getpwnam(s))) {
271                            parse_error("user");
272                        }
273                        sct->m_uid = pwd->pw_uid;
274                    }
275
276                    sct->m_gid = strtoul(e, &e2, 10);
277                    if (*e2 || (e == e2)) {
278                        struct group *grp;
279                        if (!(grp = getgrnam(e))) {
280                            parse_error("group");
281                        }
282                        sct->m_gid = grp->gr_gid;
283                    }
284                }
285            }
286            continue;
287        }
288
289        /* Unknown sections are ignored. */
290
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. */
296        if (!section) {
297            parse_error("keyword outside section");
298        }
299
300    } while (1);
301
302 pe_label:
303    fprintf(stderr, "Parse error in %s, line %d: %s\n",
304            config_file, lc, err);
305
306    fclose(f);
307    /* Release any allocated memory before returning. */
308    while (sct_head) {
309        sct = sct_head->m_next;
310        free(sct_head);
311        sct_head = sct;
312    }
313    return;
314}
315
316#else
317#define parse_config_file()
318#endif /* CONFIG_FEATURE_SUID_CONFIG */
319
320#ifdef CONFIG_FEATURE_SUID
321static void check_suid (struct BB_applet *applet)
322{
323  uid_t ruid = getuid ();               /* real [ug]id */
324  uid_t rgid = getgid ();
325
326#ifdef CONFIG_FEATURE_SUID_CONFIG
327  if (suid_cfg_readable) {
328    struct BB_suid_config *sct;
329
330    for (sct = suid_config; sct; sct = sct->m_next) {
331      if (sct->m_applet == applet)
332        break;
333    }
334    if (sct) {
335      mode_t m = sct->m_mode;
336
337      if (sct->m_uid == ruid)       /* same uid */
338        m >>= 6;
339      else if ((sct->m_gid == rgid) || ingroup (ruid, sct->m_gid))  /* same group / in group */
340        m >>= 3;
341
342      if (!(m & S_IXOTH))           /* is x bit not set ? */
343        bb_error_msg_and_die ("You have no permission to run this applet!");
344
345      if ((sct->m_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {     /* *both* have to be set for sgid */
346        if (setegid (sct->m_gid))
347          bb_error_msg_and_die
348            ("BusyBox binary has insufficient rights to set proper GID for applet!");
349      } else
350        setgid (rgid);                  /* no sgid -> drop */
351
352      if (sct->m_mode & S_ISUID) {
353        if (seteuid (sct->m_uid))
354          bb_error_msg_and_die
355            ("BusyBox binary has insufficient rights to set proper UID for applet!");
356      } else
357        setuid (ruid);                  /* no suid -> drop */
358    } else {
359        /* default: drop all privileges */
360      setgid (rgid);
361      setuid (ruid);
362    }
363    return;
364  } else {
365#ifndef CONFIG_FEATURE_SUID_CONFIG_QUIET
366    static int onetime = 0;
367
368    if (!onetime) {
369      onetime = 1;
370      fprintf (stderr, "Using fallback suid method\n");
371    }
372#endif
373  }
374#endif
375
376  if (applet->need_suid == _BB_SUID_ALWAYS) {
377    if (geteuid () != 0)
378      bb_error_msg_and_die ("This applet requires root privileges!");
379  } else if (applet->need_suid == _BB_SUID_NEVER) {
380    setgid (rgid);                          /* drop all privileges */
381    setuid (ruid);
382  }
383}
384#else
385#define check_suid(x)
386#endif /* CONFIG_FEATURE_SUID */
387
388
389
390#if ENABLE_FEATURE_COMPRESS_USAGE
391
392#include "usage_compressed.h"
393#include "unarchive.h"
394
395static const char *unpack_usage_messages(void)
396{
397    int input[2], output[2], pid;
398    char *buf;
399
400    if(pipe(input) < 0 || pipe(output) < 0)
401        exit(1);
402
403    pid = fork();
404    switch (pid) {
405    case -1: /* error */
406        exit(1);
407    case 0: /* child */
408        close(input[1]);
409        close(output[0]);
410        uncompressStream(input[0], output[1]);
411        exit(0);
412    }
413    /* parent */
414
415    close(input[0]);
416    close(output[1]);
417    pid = fork();
418    switch (pid) {
419    case -1: /* error */
420        exit(1);
421    case 0: /* child */
422        bb_full_write(input[1], packed_usage, sizeof(packed_usage));
423        exit(0);
424    }
425    /* parent */
426    close(input[1]);
427
428    buf = xmalloc(SIZEOF_usage_messages);
429    bb_full_read(output[0], buf, SIZEOF_usage_messages);
430    return buf;
431}
432
433#else
434#define unpack_usage_messages() usage_messages
435#endif /* ENABLE_FEATURE_COMPRESS_USAGE */
436
437void bb_show_usage (void)
438{
439    if (ENABLE_SHOW_USAGE) {
440        const char *format_string;
441        const char *usage_string = unpack_usage_messages();
442        int i;
443
444        for (i = applet_using - applets; i > 0;)
445            if (!*usage_string++) --i;
446
447        format_string = "%s\n\nUsage: %s %s\n\n";
448        if (*usage_string == '\b')
449            format_string = "%s\n\nNo help available.\n\n";
450        fprintf (stderr, format_string, bb_msg_full_version,
451            applet_using->name, usage_string);
452    }
453
454  exit (bb_default_error_retval);
455}
456
457static int applet_name_compare (const void *x, const void *y)
458{
459  const char *name = x;
460  const struct BB_applet *applet = y;
461
462  return strcmp (name, applet->name);
463}
464
465extern const size_t NUM_APPLETS;
466
467struct BB_applet *find_applet_by_name (const char *name)
468{
469  return bsearch (name, applets, NUM_APPLETS, sizeof (struct BB_applet),
470                  applet_name_compare);
471}
472
473void run_applet_by_name (const char *name, int argc, char **argv)
474{
475    if(ENABLE_FEATURE_SUID_CONFIG) parse_config_file ();
476
477    if(!strncmp(name, "busybox", 7)) busybox_main(argc, argv);
478    /* Do a binary search to find the applet entry given the name. */
479    applet_using = find_applet_by_name(name);
480    if(applet_using) {
481        bb_applet_name = applet_using->name;
482        if(argc==2 && !strcmp(argv[1], "--help")) bb_show_usage ();
483        if(ENABLE_FEATURE_SUID) check_suid (applet_using);
484        exit ((*(applet_using->main)) (argc, argv));
485    }
486}
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