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text data bss dec hex filename 861791 11264 1039140 1912195 1d2d83 busybox.have-terse-usage 854799 11264 1039140 1905203 1d1233 busybox.no-terse
473 lines
12 KiB
C
473 lines
12 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Utility routines.
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*
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* Copyright (C) tons of folks. Tracking down who wrote what
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* isn't something I'm going to worry about... If you wrote something
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* here, please feel free to acknowledge your work.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* Based in part on code from sash, Copyright (c) 1999 by David I. Bell
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* Permission has been granted to redistribute this code under the GPL.
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*
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*/
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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#include "busybox.h"
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#if ENABLE_SHOW_USAGE
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const char usage_messages[] =
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#define MAKE_USAGE
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#include "usage.h"
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#include "applets.h"
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;
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#undef MAKE_USAGE
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#endif /* ENABLE_SHOW_USAGE */
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#undef APPLET
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#undef APPLET_NOUSAGE
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#undef PROTOTYPES
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#include "applets.h"
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static struct BB_applet *applet_using;
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/* The -1 arises because of the {0,NULL,0,-1} entry above. */
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const size_t NUM_APPLETS = (sizeof (applets) / sizeof (struct BB_applet) - 1);
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#ifdef CONFIG_FEATURE_SUID_CONFIG
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#include <sys/stat.h>
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#include <ctype.h>
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#include "pwd_.h"
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#include "grp_.h"
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#define CONFIG_FILE "/etc/busybox.conf"
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/* applets [] is const, so we have to define this "override" structure */
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static struct BB_suid_config
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{
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struct BB_applet *m_applet;
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uid_t m_uid;
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gid_t m_gid;
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mode_t m_mode;
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struct BB_suid_config *m_next;
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} *suid_config;
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static int suid_cfg_readable;
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/* 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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{
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struct group *grp = getgrgid (g);
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if (grp) {
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char **mem;
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for (mem = grp->gr_mem; *mem; mem++) {
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struct passwd *pwd = getpwnam (*mem);
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if (pwd && (pwd->pw_uid == u))
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return 1;
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}
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}
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return 0;
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}
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/* This should probably be a libbb routine. In that case,
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* I'd probably rename it to something like bb_trimmed_slice.
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*/
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static char *get_trimmed_slice(char *s, char *e)
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{
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/* First, consider the value at e to be nul and back up until we
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* reach a non-space char. Set the char after that (possibly at
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* the original e) to nul. */
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while (e-- > s) {
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if (!isspace(*e)) {
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break;
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}
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}
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e[1] = 0;
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/* Next, advance past all leading space and return a ptr to the
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* first non-space char; possibly the terminating nul. */
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return (char *) bb_skip_whitespace(s);
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}
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#define parse_error(x) { err=x; goto pe_label; }
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/* Don't depend on the tools to combine strings. */
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static const char config_file[] = CONFIG_FILE;
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/* There are 4 chars + 1 nul for each of user/group/other. */
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static const char mode_chars[] = "Ssx-\0Ssx-\0Ttx-";
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/* We don't supply a value for the nul, so an index adjustment is
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* necessary below. Also, we use unsigned short here to save some
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* space even though these are really mode_t values. */
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static const unsigned short mode_mask[] = {
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/* SST sst xxx --- */
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S_ISUID, S_ISUID|S_IXUSR, S_IXUSR, 0, /* user */
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S_ISGID, S_ISGID|S_IXGRP, S_IXGRP, 0, /* group */
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0, S_IXOTH, S_IXOTH, 0 /* other */
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};
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static void parse_config_file(void)
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{
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struct BB_suid_config *sct_head;
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struct BB_suid_config *sct;
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struct BB_applet *applet;
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FILE *f;
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char *err;
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char *s;
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char *e;
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int i, lc, section;
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char buffer[256];
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struct stat st;
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assert(!suid_config); /* Should be set to NULL by bss init. */
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if ((stat(config_file, &st) != 0) /* No config file? */
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|| !S_ISREG(st.st_mode) /* Not a regular file? */
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|| (st.st_uid != 0) /* Not owned by root? */
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|| (st.st_mode & (S_IWGRP | S_IWOTH)) /* Writable by non-root? */
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|| !(f = fopen(config_file, "r")) /* Can not open? */
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) {
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return;
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}
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suid_cfg_readable = 1;
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sct_head = NULL;
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section = lc = 0;
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do {
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s = buffer;
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if (!fgets(s, sizeof(buffer), f)) { /* Are we done? */
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if (ferror(f)) { /* Make sure it wasn't a read error. */
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parse_error("reading");
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}
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fclose(f);
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suid_config = sct_head; /* Success, so set the pointer. */
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return;
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}
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lc++; /* Got a (partial) line. */
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/* If a line is too long for our buffer, we consider it an error.
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* The following test does mistreat one corner case though.
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* If the final line of the file does not end with a newline and
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* yet exactly fills the buffer, it will be treated as too long
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* even though there isn't really a problem. But it isn't really
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* worth adding code to deal with such an unlikely situation, and
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* we do err on the side of caution. Besides, the line would be
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* too long if it did end with a newline. */
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if (!strchr(s, '\n') && !feof(f)) {
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parse_error("line too long");
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}
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/* Trim leading and trailing whitespace, ignoring comments, and
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* check if the resulting string is empty. */
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if (!*(s = get_trimmed_slice(s, strchrnul(s, '#')))) {
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continue;
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}
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/* Check for a section header. */
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if (*s == '[') {
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/* Unlike the old code, we ignore leading and trailing
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* whitespace for the section name. We also require that
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* there are no stray characters after the closing bracket. */
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if (!(e = strchr(s, ']')) /* Missing right bracket? */
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|| e[1] /* Trailing characters? */
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|| !*(s = get_trimmed_slice(s+1, e)) /* Missing name? */
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) {
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parse_error("section header");
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}
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/* Right now we only have one section so just check it.
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* If more sections are added in the future, please don't
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* resort to cascading ifs with multiple strcasecmp calls.
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* That kind of bloated code is all too common. A loop
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* and a string table would be a better choice unless the
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* number of sections is very small. */
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if (strcasecmp(s, "SUID") == 0) {
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section = 1;
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continue;
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}
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section = -1; /* Unknown section so set to skip. */
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continue;
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}
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/* Process sections. */
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if (section == 1) { /* SUID */
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/* Since we trimmed leading and trailing space above, we're
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* now looking for strings of the form
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* <key>[::space::]*=[::space::]*<value>
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* where both key and value could contain inner whitespace. */
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/* First get the key (an applet name in our case). */
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if (!!(e = strchr(s, '='))) {
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s = get_trimmed_slice(s, e);
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}
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if (!e || !*s) { /* Missing '=' or empty key. */
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parse_error("keyword");
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}
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/* Ok, we have an applet name. Process the rhs if this
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* applet is currently built in and ignore it otherwise.
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* Note: This can hide config file bugs which only pop
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* up when the busybox configuration is changed. */
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if ((applet = find_applet_by_name(s))) {
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/* Note: We currently don't check for duplicates!
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* The last config line for each applet will be the
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* one used since we insert at the head of the list.
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* I suppose this could be considered a feature. */
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sct = xmalloc(sizeof(struct BB_suid_config));
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sct->m_applet = applet;
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sct->m_mode = 0;
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sct->m_next = sct_head;
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sct_head = sct;
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/* Get the specified mode. */
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e = (char *) bb_skip_whitespace(e+1);
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for (i=0 ; i < 3 ; i++) {
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const char *q;
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if (!*(q = strchrnul(mode_chars + 5*i, *e++))) {
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parse_error("mode");
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}
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/* Adjust by -i to account for nul. */
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sct->m_mode |= mode_mask[(q - mode_chars) - i];
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}
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/* Now get the the user/group info. */
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s = (char *) bb_skip_whitespace(e);
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/* Note: We require whitespace between the mode and the
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* user/group info. */
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if ((s == e) || !(e = strchr(s, '.'))) {
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parse_error("<uid>.<gid>");
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}
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*e++ = 0;
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/* We can't use get_ug_id here since it would exit()
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* if a uid or gid was not found. Oh well... */
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{
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char *e2;
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sct->m_uid = strtoul(s, &e2, 10);
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if (*e2 || (s == e2)) {
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struct passwd *pwd;
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if (!(pwd = getpwnam(s))) {
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parse_error("user");
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}
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sct->m_uid = pwd->pw_uid;
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}
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sct->m_gid = strtoul(e, &e2, 10);
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if (*e2 || (e == e2)) {
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struct group *grp;
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if (!(grp = getgrnam(e))) {
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parse_error("group");
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}
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sct->m_gid = grp->gr_gid;
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}
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}
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}
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continue;
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}
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/* Unknown sections are ignored. */
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/* Encountering configuration lines prior to seeing a
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* section header is treated as an error. This is how
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* the old code worked, but it may not be desirable.
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* We may want to simply ignore such lines in case they
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* are used in some future version of busybox. */
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if (!section) {
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parse_error("keyword outside section");
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}
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} while (1);
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pe_label:
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fprintf(stderr, "Parse error in %s, line %d: %s\n",
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config_file, lc, err);
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fclose(f);
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/* Release any allocated memory before returning. */
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while (sct_head) {
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sct = sct_head->m_next;
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free(sct_head);
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sct_head = sct;
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}
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return;
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}
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#else
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#define parse_config_file()
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#endif /* CONFIG_FEATURE_SUID_CONFIG */
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#ifdef CONFIG_FEATURE_SUID
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static void check_suid (struct BB_applet *applet)
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{
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uid_t ruid = getuid (); /* real [ug]id */
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uid_t rgid = getgid ();
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#ifdef CONFIG_FEATURE_SUID_CONFIG
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if (suid_cfg_readable) {
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struct BB_suid_config *sct;
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for (sct = suid_config; sct; sct = sct->m_next) {
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if (sct->m_applet == applet)
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break;
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}
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if (sct) {
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mode_t m = sct->m_mode;
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if (sct->m_uid == ruid) /* same uid */
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m >>= 6;
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else if ((sct->m_gid == rgid) || ingroup (ruid, sct->m_gid)) /* same group / in group */
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m >>= 3;
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if (!(m & S_IXOTH)) /* is x bit not set ? */
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bb_error_msg_and_die ("You have no permission to run this applet!");
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if ((sct->m_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { /* *both* have to be set for sgid */
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if (setegid (sct->m_gid))
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bb_error_msg_and_die
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("BusyBox binary has insufficient rights to set proper GID for applet!");
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} else
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setgid (rgid); /* no sgid -> drop */
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if (sct->m_mode & S_ISUID) {
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if (seteuid (sct->m_uid))
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bb_error_msg_and_die
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("BusyBox binary has insufficient rights to set proper UID for applet!");
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} else
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setuid (ruid); /* no suid -> drop */
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} else {
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/* default: drop all privileges */
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setgid (rgid);
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setuid (ruid);
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}
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return;
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} else {
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#ifndef CONFIG_FEATURE_SUID_CONFIG_QUIET
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static int onetime = 0;
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if (!onetime) {
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onetime = 1;
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fprintf (stderr, "Using fallback suid method\n");
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}
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#endif
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}
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#endif
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if (applet->need_suid == _BB_SUID_ALWAYS) {
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if (geteuid () != 0)
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bb_error_msg_and_die ("This applet requires root privileges!");
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} else if (applet->need_suid == _BB_SUID_NEVER) {
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setgid (rgid); /* drop all privileges */
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setuid (ruid);
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}
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}
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#else
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#define check_suid(x)
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#endif /* CONFIG_FEATURE_SUID */
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void bb_show_usage (void)
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{
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#if ENABLE_SHOW_USAGE
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const char *format_string;
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const char *usage_string = usage_messages;
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int i;
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for (i = applet_using - applets; i > 0;) {
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if (!*usage_string++) {
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--i;
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}
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}
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format_string = "%s\n\nUsage: %s %s\n\n";
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if (*usage_string == '\b')
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format_string = "%s\n\nNo help available.\n\n";
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fprintf (stderr, format_string, bb_msg_full_version, applet_using->name,
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usage_string);
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#endif /* ENABLE_SHOW_USAGE */
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exit (bb_default_error_retval);
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}
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static int applet_name_compare (const void *x, const void *y)
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{
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const char *name = x;
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const struct BB_applet *applet = y;
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return strcmp (name, applet->name);
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}
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extern const size_t NUM_APPLETS;
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struct BB_applet *find_applet_by_name (const char *name)
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{
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return bsearch (name, applets, NUM_APPLETS, sizeof (struct BB_applet),
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applet_name_compare);
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}
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void run_applet_by_name (const char *name, int argc, char **argv)
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{
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if(ENABLE_FEATURE_SUID_CONFIG) parse_config_file ();
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if(!strncmp(name, "busybox", 7)) busybox_main(argc, argv);
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/* Do a binary search to find the applet entry given the name. */
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applet_using = find_applet_by_name(name);
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if(applet_using) {
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bb_applet_name = applet_using->name;
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if(argc==2 && !strcmp(argv[1], "--help")) bb_show_usage ();
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if(ENABLE_FEATURE_SUID) check_suid (applet_using);
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exit ((*(applet_using->main)) (argc, argv));
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}
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}
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/* END CODE */
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/*
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Local Variables:
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c-file-style: "linux"
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c-basic-offset: 4
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tab-width: 4
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End:
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*/
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