Diff of /trunk/mkinitrd-magellan/busybox/applets/applets.c

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	revision 815 by niro, Sat Sep 1 22:45:15 2007 UTC	revision 816 by niro, Fri Apr 24 18:33:46 2009 UTC
#	Line 1	Line 1
1	/* vi: set sw=4 ts=4: */	/* vi: set sw=4 ts=4: */
2	/*	/*
3	* Utility routines.	* Stub for linking busybox binary against libbusybox.
4	*	*
5	* Copyright (C) tons of folks.  Tracking down who wrote what	* Copyright (C) 2007 Denys Vlasenko <vda.linux@googlemail.com>
	* isn't something I'm going to worry about...  If you wrote something
	* here, please feel free to acknowledge your work.
6	*	*
7	* Based in part on code from sash, Copyright (c) 1999 by David I. Bell	* Licensed under GPLv2, see file License in this tarball for details.
	* Permission has been granted to redistribute this code under the GPL.
	*
	* Licensed under GPLv2 or later, see file License in this tarball for details.
8	*/	*/
9
	#include "busybox.h"
10	#include <assert.h>	#include <assert.h>
11		#include "busybox.h"
12
13	/* Apparently uclibc defines __GLIBC__ (compat trick?). Oh well. */	#if ENABLE_BUILD_LIBBUSYBOX
14	#if ENABLE_STATIC && defined(__GLIBC__) && !defined(__UCLIBC__)	int main(int argc UNUSED_PARAM, char **argv)
	#warning Static linking against glibc produces buggy executables
	#warning (glibc does not cope well with ld --gc-sections).
	#warning See sources.redhat.com/bugzilla/show_bug.cgi?id=3400
	#warning Note that glibc is unsuitable for static linking anyway.
	#warning If you still want to do it, remove -Wl,--gc-sections
	#warning from top-level Makefile and remove this warning.
	#endif
	#if ENABLE_SHOW_USAGE && !ENABLE_FEATURE_COMPRESS_USAGE
	static const char usage_messages[] =
	#define MAKE_USAGE
	#include "usage.h"
	#include "applets.h"
	;
	#undef MAKE_USAGE
	#else
	#define usage_messages 0
	#endif /* ENABLE_SHOW_USAGE */
	#undef APPLET
	#undef APPLET_NOUSAGE
	#undef PROTOTYPES
	#include "applets.h"
	static struct BB_applet *applet_using;
	/* The -1 arises because of the {0,NULL,0,-1} entry above. */
	const unsigned short NUM_APPLETS = (sizeof (applets) / sizeof (struct BB_applet) - 1);
	#ifdef CONFIG_FEATURE_SUID_CONFIG
	#include <ctype.h>
	#define CONFIG_FILE "/etc/busybox.conf"
	/* applets [] is const, so we have to define this "override" structure */
	static struct BB_suid_config
	{
	struct BB_applet *m_applet;
	uid_t m_uid;
	gid_t m_gid;
	mode_t m_mode;
	struct BB_suid_config *m_next;
	} *suid_config;
	static int suid_cfg_readable;
	/* check if u is member of group g */
	static int ingroup(uid_t u, gid_t g)
	{
	struct group *grp = getgrgid(g);
	if (grp) {
	char **mem;
	for (mem = grp->gr_mem; *mem; mem++) {
	struct passwd *pwd = getpwnam(*mem);
	if (pwd && (pwd->pw_uid == u))
	return 1;
	}
	}
	return 0;
	}
	/* This should probably be a libbb routine.  In that case,
	* I'd probably rename it to something like bb_trimmed_slice.
	*/
	static char *get_trimmed_slice(char *s, char *e)
15	{	{
16	/* First, consider the value at e to be nul and back up until we	return lbb_main(argv);
	* reach a non-space char.  Set the char after that (possibly at
	* the original e) to nul. */
	while (e-- > s) {
	if (!isspace(*e)) {
	break;
	}
	}
	e[1] = 0;
	/* Next, advance past all leading space and return a ptr to the
	* first non-space char; possibly the terminating nul. */
	return skip_whitespace(s);
17	}	}
	#define parse_error(x)  { err=x; goto pe_label; }
	/* Don't depend on the tools to combine strings. */
	static const char config_file[] = CONFIG_FILE;
	/* There are 4 chars + 1 nul for each of user/group/other. */
	static const char mode_chars[] = "Ssx-\0Ssx-\0Ttx-";
	/* We don't supply a value for the nul, so an index adjustment is
	* necessary below.  Also, we use unsigned short here to save some
	* space even though these are really mode_t values. */
	static const unsigned short mode_mask[] = {
	/*  SST         sst                 xxx   --- */
	S_ISUID,    S_ISUID|S_IXUSR,    S_IXUSR,    0, /* user */
	S_ISGID,    S_ISGID|S_IXGRP,    S_IXGRP,    0, /* group */
	0,          S_IXOTH,            S_IXOTH,    0 /* other */
	};
	static void parse_config_file(void)
	{
	struct BB_suid_config *sct_head;
	struct BB_suid_config *sct;
	struct BB_applet *applet;
	FILE *f;
	char *err;
	char *s;
	char *e;
	int i, lc, section;
	char buffer[256];
	struct stat st;
	assert(!suid_config); /* Should be set to NULL by bss init. */
	if ((stat(config_file, &st) != 0) /* No config file? */
	|| !S_ISREG(st.st_mode) /* Not a regular file? */
	|| (st.st_uid != 0) /* Not owned by root? */
	|| (st.st_mode & (S_IWGRP | S_IWOTH)) /* Writable by non-root? */
	|| !(f = fopen(config_file, "r")) /* Cannot open? */
	) {
	return;
	}
	suid_cfg_readable = 1;
	sct_head = NULL;
	section = lc = 0;
	do {
	s = buffer;
	if (!fgets(s, sizeof(buffer), f)) { /* Are we done? */
	if (ferror(f)) {   /* Make sure it wasn't a read error. */
	parse_error("reading");
	}
	fclose(f);
	suid_config = sct_head; /* Success, so set the pointer. */
	return;
	}
	lc++; /* Got a (partial) line. */
	/* If a line is too long for our buffer, we consider it an error.
	* The following test does mistreat one corner case though.
	* If the final line of the file does not end with a newline and
	* yet exactly fills the buffer, it will be treated as too long
	* even though there isn't really a problem.  But it isn't really
	* worth adding code to deal with such an unlikely situation, and
	* we do err on the side of caution.  Besides, the line would be
	* too long if it did end with a newline. */
	if (!strchr(s, '\n') && !feof(f)) {
	parse_error("line too long");
	}
	/* Trim leading and trailing whitespace, ignoring comments, and
	* check if the resulting string is empty. */
	if (!*(s = get_trimmed_slice(s, strchrnul(s, '#')))) {
	continue;
	}
	/* Check for a section header. */
	if (*s == '[') {
	/* Unlike the old code, we ignore leading and trailing
	* whitespace for the section name.  We also require that
	* there are no stray characters after the closing bracket. */
	if (!(e = strchr(s, ']')) /* Missing right bracket? */
	|| e[1] /* Trailing characters? */
	|| !*(s = get_trimmed_slice(s+1, e)) /* Missing name? */
	) {
	parse_error("section header");
	}
	/* Right now we only have one section so just check it.
	* If more sections are added in the future, please don't
	* resort to cascading ifs with multiple strcasecmp calls.
	* That kind of bloated code is all too common.  A loop
	* and a string table would be a better choice unless the
	* number of sections is very small. */
	if (strcasecmp(s, "SUID") == 0) {
	section = 1;
	continue;
	}
	section = -1; /* Unknown section so set to skip. */
	continue;
	}
	/* Process sections. */
	if (section == 1) { /* SUID */
	/* Since we trimmed leading and trailing space above, we're
	* now looking for strings of the form
	*    <key>[::space::]*=[::space::]*<value>
	* where both key and value could contain inner whitespace. */
	/* First get the key (an applet name in our case). */
	if (!!(e = strchr(s, '='))) {
	s = get_trimmed_slice(s, e);
	}
	if (!e || !*s) { /* Missing '=' or empty key. */
	parse_error("keyword");
	}
	/* Ok, we have an applet name.  Process the rhs if this
	* applet is currently built in and ignore it otherwise.
	* Note: This can hide config file bugs which only pop
	* up when the busybox configuration is changed. */
	if ((applet = find_applet_by_name(s))) {
	/* Note: We currently don't check for duplicates!
	* The last config line for each applet will be the
	* one used since we insert at the head of the list.
	* I suppose this could be considered a feature. */
	sct = xmalloc(sizeof(struct BB_suid_config));
	sct->m_applet = applet;
	sct->m_mode = 0;
	sct->m_next = sct_head;
	sct_head = sct;
	/* Get the specified mode. */
	e = skip_whitespace(e+1);
	for (i=0 ; i < 3 ; i++) {
	const char *q;
	if (!*(q = strchrnul(mode_chars + 5*i, *e++))) {
	parse_error("mode");
	}
	/* Adjust by -i to account for nul. */
	sct->m_mode |= mode_mask[(q - mode_chars) - i];
	}
	/* Now get the the user/group info. */
	s = skip_whitespace(e);
	/* Note: We require whitespace between the mode and the
	* user/group info. */
	if ((s == e) || !(e = strchr(s, '.'))) {
	parse_error("<uid>.<gid>");
	}
	*e++ = 0;
	/* We can't use get_ug_id here since it would exit()
	* if a uid or gid was not found.  Oh well... */
	{
	char *e2;
	sct->m_uid = strtoul(s, &e2, 10);
	if (*e2 || (s == e2)) {
	struct passwd *pwd = getpwnam(s);
	if (!pwd) {
	parse_error("user");
	}
	sct->m_uid = pwd->pw_uid;
	}
	sct->m_gid = strtoul(e, &e2, 10);
	if (*e2 || (e == e2)) {
	struct group *grp;
	if (!(grp = getgrnam(e))) {
	parse_error("group");
	}
	sct->m_gid = grp->gr_gid;
	}
	}
	}
	continue;
	}
	/* Unknown sections are ignored. */
	/* Encountering configuration lines prior to seeing a
	* section header is treated as an error.  This is how
	* the old code worked, but it may not be desirable.
	* We may want to simply ignore such lines in case they
	* are used in some future version of busybox. */
	if (!section) {
	parse_error("keyword outside section");
	}
	} while (1);
	pe_label:
	fprintf(stderr, "Parse error in %s, line %d: %s\n",
	config_file, lc, err);
	fclose(f);
	/* Release any allocated memory before returning. */
	while (sct_head) {
	sct = sct_head->m_next;
	free(sct_head);
	sct_head = sct;
	}
	return;
	}
	#else
	#define parse_config_file() ((void)0)
	#endif /* CONFIG_FEATURE_SUID_CONFIG */
	#ifdef CONFIG_FEATURE_SUID
	static void check_suid(struct BB_applet *applet)
	{
	uid_t ruid = getuid();               /* real [ug]id */
	uid_t rgid = getgid();
	#ifdef CONFIG_FEATURE_SUID_CONFIG
	if (suid_cfg_readable) {
	struct BB_suid_config *sct;
	for (sct = suid_config; sct; sct = sct->m_next) {
	if (sct->m_applet == applet)
	break;
	}
	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_gid != 0) {
	/* _both_ have to be set for sgid */
	if ((sct->m_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
	xsetgid(sct->m_gid);
	} else xsetgid(rgid); /* no sgid -> drop */
	}
	if (sct->m_uid != 0) {
	if (sct->m_mode & S_ISUID) xsetuid(sct->m_uid);
	else xsetuid(ruid); /* no suid -> drop */
	}
	} else {
	/* default: drop all privileges */
	xsetgid(rgid);
	xsetuid(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
	}
18	#endif	#endif
	if (applet->need_suid == _BB_SUID_ALWAYS) {
	if (geteuid()) bb_error_msg_and_die("applet requires root privileges!");
	} else if (applet->need_suid == _BB_SUID_NEVER) {
	xsetgid(rgid);                          /* drop all privileges */
	xsetuid(ruid);
	}
	}
	#else
	#define check_suid(x)
	#endif /* CONFIG_FEATURE_SUID */
	#ifdef CONFIG_FEATURE_COMPRESS_USAGE
	#include "usage_compressed.h"
	#include "unarchive.h"
	static const char *unpack_usage_messages(void)
	{
	int input[2], output[2], pid;
	char *buf;
	if(pipe(input) < 0 || pipe(output) < 0)
	exit(1);
	pid = fork();
	switch (pid) {
	case -1: /* error */
	exit(1);
	case 0: /* child */
	close(input[1]);
	close(output[0]);
	uncompressStream(input[0], output[1]);
	exit(0);
	}
	/* parent */
	close(input[0]);
	close(output[1]);
	pid = fork();
	switch (pid) {
	case -1: /* error */
	exit(1);
	case 0: /* child */
	full_write(input[1], packed_usage, sizeof(packed_usage));
	exit(0);
	}
	/* parent */
	close(input[1]);
	buf = xmalloc(SIZEOF_usage_messages);
	full_read(output[0], buf, SIZEOF_usage_messages);
	return buf;
	}
	#else
	#define unpack_usage_messages() usage_messages
	#endif /* ENABLE_FEATURE_COMPRESS_USAGE */
	void bb_show_usage(void)
	{
	if (ENABLE_SHOW_USAGE) {
	const char *format_string;
	const char *usage_string = unpack_usage_messages();
	int i;
	for (i = applet_using - applets; i > 0;)
	if (!*usage_string++) --i;
	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);
	}
	exit(xfunc_error_retval);
	}
	static int applet_name_compare(const void *name, const void *vapplet)
	{
	const struct BB_applet *applet = vapplet;
	return strcmp(name, applet->name);
	}
	struct BB_applet *find_applet_by_name(const char *name)
	{
	return bsearch(name, applets, NUM_APPLETS, sizeof(struct BB_applet),
	applet_name_compare);
	}
	void run_applet_by_name(const char *name, int argc, char **argv)
	{
	if (ENABLE_FEATURE_SUID_CONFIG)
	parse_config_file();
	if (!strncmp(name, "busybox", 7))
	exit(busybox_main(argc, argv));
	/* Do a binary search to find the applet entry given the name. */
	applet_using = find_applet_by_name(name);
	if (applet_using) {
	applet_name = applet_using->name;
	if (argc == 2 && !strcmp(argv[1], "--help"))
	bb_show_usage();
	if (ENABLE_FEATURE_SUID)
	check_suid(applet_using);
	exit(applet_using->main(argc, argv));
	}
	}

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