busybox/applets/applets.c

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/* vi: set sw=4 ts=4: */
/*
* Utility routines.
*
* Copyright (C) tons of folks. Tracking down who wrote what
* isn't something I'm going to worry about... If you wrote something
* here, please feel free to acknowledge your work.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
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* Based in part on code from sash, Copyright (c) 1999 by David I. Bell
* Permission has been granted to redistribute this code under the GPL.
*
*/
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
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#include <string.h>
#include "busybox.h"
#undef APPLET
#undef APPLET_NOUSAGE
#undef PROTOTYPES
#include "applets.h"
struct BB_applet *applet_using;
/* The -1 arises because of the {0,NULL,0,-1} entry above. */
const size_t NUM_APPLETS = (sizeof (applets) / sizeof (struct BB_applet) - 1);
#ifdef CONFIG_FEATURE_SUID
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static void check_suid (struct BB_applet *app);
#ifdef CONFIG_FEATURE_SUID_CONFIG
#include <sys/stat.h>
#include <ctype.h>
#include "pwd_.h"
#include "grp_.h"
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static int parse_config_file (void);
static int config_ok;
#define CONFIG_FILE "/etc/busybox.conf"
/* applets [] is const, so we have to define this "override" structure */
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struct BB_suid_config
{
struct BB_applet *m_applet;
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uid_t m_uid;
gid_t m_gid;
mode_t m_mode;
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struct BB_suid_config *m_next;
};
static struct BB_suid_config *suid_config;
#endif /* CONFIG_FEATURE_SUID_CONFIG */
#endif /* CONFIG_FEATURE_SUID */
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extern void
bb_show_usage (void)
{
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const char *format_string;
const char *usage_string = usage_messages;
int i;
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for (i = applet_using - applets; i > 0;) {
if (!*usage_string++) {
--i;
}
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}
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format_string = "%s\n\nUsage: %s %s\n\n";
if (*usage_string == '\b')
format_string = "%s\n\nNo help available.\n\n";
fprintf (stderr, format_string, bb_msg_full_version, applet_using->name,
usage_string);
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exit (EXIT_FAILURE);
}
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static int
applet_name_compare (const void *x, const void *y)
{
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const char *name = x;
const struct BB_applet *applet = y;
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return strcmp (name, applet->name);
}
extern const size_t NUM_APPLETS;
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struct BB_applet *
find_applet_by_name (const char *name)
{
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return bsearch (name, applets, NUM_APPLETS, sizeof (struct BB_applet),
applet_name_compare);
}
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void
run_applet_by_name (const char *name, int argc, char **argv)
{
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static int recurse_level = 0;
extern int been_there_done_that; /* From busybox.c */
#ifdef CONFIG_FEATURE_SUID_CONFIG
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if (recurse_level == 0)
config_ok = parse_config_file ();
#endif
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recurse_level++;
/* Do a binary search to find the applet entry given the name. */
if ((applet_using = find_applet_by_name (name)) != NULL) {
bb_applet_name = applet_using->name;
if (argv[1] && strcmp (argv[1], "--help") == 0) {
if (strcmp (applet_using->name, "busybox") == 0) {
if (argv[2])
applet_using = find_applet_by_name (argv[2]);
else
applet_using = NULL;
}
if (applet_using)
bb_show_usage ();
been_there_done_that = 1;
busybox_main (0, NULL);
}
#ifdef CONFIG_FEATURE_SUID
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check_suid (applet_using);
#endif
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exit ((*(applet_using->main)) (argc, argv));
}
/* Just in case they have renamed busybox - Check argv[1] */
if (recurse_level == 1) {
run_applet_by_name ("busybox", argc, argv);
}
recurse_level--;
}
#ifdef CONFIG_FEATURE_SUID
#ifdef CONFIG_FEATURE_SUID_CONFIG
/* check if u is member of group g */
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static int
ingroup (uid_t u, gid_t g)
{
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struct group *grp = getgrgid (g);
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if (grp) {
char **mem;
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for (mem = grp->gr_mem; *mem; mem++) {
struct passwd *pwd = getpwnam (*mem);
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if (pwd && (pwd->pw_uid == u))
return 1;
}
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}
return 0;
}
#endif
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void
check_suid (struct BB_applet *applet)
{
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uid_t ruid = getuid (); /* real [ug]id */
uid_t rgid = getgid ();
#ifdef CONFIG_FEATURE_SUID_CONFIG
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if (config_ok) {
struct BB_suid_config *sct;
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for (sct = suid_config; sct; sct = sct->m_next) {
if (sct->m_applet == applet)
break;
}
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if (sct) {
mode_t m = sct->m_mode;
if (sct->m_uid == ruid) /* same uid */
m >>= 6;
else if ((sct->m_gid == rgid) || ingroup (ruid, sct->m_gid)) /* same group / in group */
m >>= 3;
if (!(m & S_IXOTH)) /* is x bit not set ? */
bb_error_msg_and_die ("You have no permission to run this applet!");
if ((sct->m_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { /* *both* have to be set for sgid */
if (setegid (sct->m_gid))
bb_error_msg_and_die
("BusyBox binary has insufficient rights to set proper GID for applet!");
} else
setgid (rgid); /* no sgid -> drop */
if (sct->m_mode & S_ISUID) {
if (seteuid (sct->m_uid))
bb_error_msg_and_die
("BusyBox binary has insufficient rights to set proper UID for applet!");
} else
setuid (ruid); /* no suid -> drop */
} else {
/* default: drop all priviledges */
setgid (rgid);
setuid (ruid);
}
return;
} else {
#ifndef CONFIG_FEATURE_SUID_CONFIG_QUIET
static int onetime = 0;
if (!onetime) {
onetime = 1;
fprintf (stderr, "Using fallback suid method\n");
}
#endif
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}
#endif
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if (applet->need_suid == _BB_SUID_ALWAYS) {
if (geteuid () != 0)
bb_error_msg_and_die ("This applet requires root priviledges!");
} else if (applet->need_suid == _BB_SUID_NEVER) {
setgid (rgid); /* drop all priviledges */
setuid (ruid);
}
}
#ifdef CONFIG_FEATURE_SUID_CONFIG
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#define parse_error(x) { err=x; goto pe_label; }
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int
parse_config_file (void)
{
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struct stat st;
char *err = 0;
FILE *f = 0;
int lc = 0;
suid_config = 0;
/* is there a config file ? */
if (stat (CONFIG_FILE, &st) == 0) {
/* is it owned by root with no write perm. for group and others ? */
if (S_ISREG (st.st_mode) && (st.st_uid == 0)
&& (!(st.st_mode & (S_IWGRP | S_IWOTH)))) {
/* that's ok .. then try to open it */
f = fopen (CONFIG_FILE, "r");
if (f) {
char buffer[256];
int section = 0;
while (fgets (buffer, sizeof (buffer) - 1, f)) {
char c = buffer[0];
char *p;
lc++;
p = strchr (buffer, '#');
if (p)
*p = 0;
p = buffer + bb_strlen (buffer);
while ((p > buffer) && isspace (*--p))
*p = 0;
if (p == buffer)
continue;
if (c == '[') {
p = strchr (buffer, ']');
if (!p || (p == (buffer + 1))) /* no matching ] or empty [] */
parse_error ("malformed section header");
*p = 0;
if (strcasecmp (buffer + 1, "SUID") == 0)
section = 1;
else
section = -1; /* unknown section - just skip */
} else if (section) {
switch (section) {
case 1:{ /* SUID */
int l;
struct BB_applet *applet;
p = strchr (buffer, '='); /* <key>[::space::]*=[::space::]*<value> */
if (!p || (p == (buffer + 1))) /* no = or key is empty */
parse_error ("malformed keyword");
l = p - buffer;
while (isspace (buffer[--l])) {
/* skip whitespace */
}
buffer[l + 1] = 0;
if ((applet = find_applet_by_name (buffer))) {
struct BB_suid_config *sct =
xmalloc (sizeof (struct BB_suid_config));
sct->m_applet = applet;
sct->m_next = suid_config;
suid_config = sct;
while (isspace (*++p)) {
/* skip whitespace */
}
sct->m_mode = 0;
switch (*p++) {
case 'S':
sct->m_mode |= S_ISUID;
break;
case 's':
sct->m_mode |= S_ISUID;
/* no break */
case 'x':
sct->m_mode |= S_IXUSR;
break;
case '-':
break;
default:
parse_error ("invalid user mode");
}
switch (*p++) {
case 's':
sct->m_mode |= S_ISGID;
/* no break */
case 'x':
sct->m_mode |= S_IXGRP;
break;
case 'S':
break;
case '-':
break;
default:
parse_error ("invalid group mode");
}
switch (*p) {
case 't':
case 'x':
sct->m_mode |= S_IXOTH;
break;
case 'T':
case '-':
break;
default:
parse_error ("invalid other mode");
}
while (isspace (*++p)) {
/* skip whitespace */
}
if (isdigit (*p)) {
sct->m_uid = strtol (p, &p, 10);
if (*p++ != '.')
parse_error ("parsing <uid>.<gid>");
} else {
struct passwd *pwd;
char *p2 = strchr (p, '.');
if (!p2)
parse_error ("parsing <uid>.<gid>");
*p2 = 0;
pwd = getpwnam (p);
if (!pwd)
parse_error ("invalid user name");
sct->m_uid = pwd->pw_uid;
p = p2 + 1;
}
if (isdigit (*p))
sct->m_gid = strtol (p, &p, 10);
else {
struct group *grp = getgrnam (p);
if (!grp)
parse_error ("invalid group name");
sct->m_gid = grp->gr_gid;
}
}
break;
}
default: /* unknown - skip */
break;
}
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} else
parse_error ("keyword not within section");
}
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fclose (f);
return 1;
}
}
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}
return 0; /* no config file or not readable (not an error) */
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pe_label:
fprintf (stderr, "Parse error in %s, line %d: %s\n", CONFIG_FILE, lc, err);
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if (f)
fclose (f);
return 0;
}
#endif
#endif
/* END CODE */
/*
Local Variables:
c-file-style: "linux"
c-basic-offset: 4
tab-width: 4
End:
*/