busybox/coreutils/chmod.c
Denys Vlasenko 2df4e0a370 chmod: correctly report changed modes
Chmod used to incorrectly report as changed even files for which the
mode did not change. This was caused by extra bits in the st_mode, that
were not present when parsed from passed argument in the form of octal
number.

Patch by Wolf <wolf@wolfsden.cz>.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2021-09-17 00:39:21 +02:00

194 lines
5.2 KiB
C

/* vi: set sw=4 ts=4: */
/*
* Mini chmod implementation for busybox
*
* Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
*
* Reworked by (C) 2002 Vladimir Oleynik <dzo@simtreas.ru>
* to correctly parse '-rwxgoa'
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
//config:config CHMOD
//config: bool "chmod (5.5 kb)"
//config: default y
//config: help
//config: chmod is used to change the access permission of files.
//applet:IF_CHMOD(APPLET_NOEXEC(chmod, chmod, BB_DIR_BIN, BB_SUID_DROP, chmod))
//kbuild:lib-$(CONFIG_CHMOD) += chmod.o
/* BB_AUDIT SUSv3 compliant */
/* BB_AUDIT GNU defects - unsupported long options. */
/* http://www.opengroup.org/onlinepubs/007904975/utilities/chmod.html */
//usage:#define chmod_trivial_usage
//usage: "[-R"IF_DESKTOP("cvf")"] MODE[,MODE]... FILE..."
//usage:#define chmod_full_usage "\n\n"
//usage: "MODE is octal number (bit pattern sstrwxrwxrwx) or [ugoa]{+|-|=}[rwxXst]"
//usage: "\n"
//next 4 options are the same for chmod/chown/chgrp:
//usage: "\n -R Recurse"
//usage: IF_DESKTOP(
//usage: "\n -c List changed files"
//usage: "\n -v Verbose"
//usage: "\n -f Hide errors"
//usage: )
//usage:
//usage:#define chmod_example_usage
//usage: "$ ls -l /tmp/foo\n"
//usage: "-rw-rw-r-- 1 root root 0 Apr 12 18:25 /tmp/foo\n"
//usage: "$ chmod u+x /tmp/foo\n"
//usage: "$ ls -l /tmp/foo\n"
//usage: "-rwxrw-r-- 1 root root 0 Apr 12 18:25 /tmp/foo*\n"
//usage: "$ chmod 444 /tmp/foo\n"
//usage: "$ ls -l /tmp/foo\n"
//usage: "-r--r--r-- 1 root root 0 Apr 12 18:25 /tmp/foo\n"
#include "libbb.h"
/* This is a NOEXEC applet. Be very careful! */
#define OPT_RECURSE (option_mask32 & 1)
#define OPT_VERBOSE (IF_DESKTOP(option_mask32 & 2) IF_NOT_DESKTOP(0))
#define OPT_CHANGED (IF_DESKTOP(option_mask32 & 4) IF_NOT_DESKTOP(0))
#define OPT_QUIET (IF_DESKTOP(option_mask32 & 8) IF_NOT_DESKTOP(0))
#define OPT_STR "R" IF_DESKTOP("vcf")
/* coreutils:
* chmod never changes the permissions of symbolic links; the chmod
* system call cannot change their permissions. This is not a problem
* since the permissions of symbolic links are never used.
* However, for each symbolic link listed on the command line, chmod changes
* the permissions of the pointed-to file. In contrast, chmod ignores
* symbolic links encountered during recursive directory traversals.
*/
static int FAST_FUNC fileAction(struct recursive_state *state,
const char *fileName,
struct stat *statbuf)
{
mode_t newmode;
/* match coreutils behavior */
if (state->depth == 0) {
/* statbuf holds lstat result, but we need stat (follow link) */
if (stat(fileName, statbuf))
goto err;
} else { /* depth > 0: skip links */
if (S_ISLNK(statbuf->st_mode))
return TRUE;
}
newmode = bb_parse_mode((char *)state->userData, statbuf->st_mode);
if (newmode == (mode_t)-1)
bb_error_msg_and_die("invalid mode '%s'", (char *)state->userData);
if (chmod(fileName, newmode) == 0) {
if (OPT_VERBOSE
|| (OPT_CHANGED
&& (statbuf->st_mode & 07777) != (newmode & 07777))
) {
printf("mode of '%s' changed to %04o (%s)\n", fileName,
newmode & 07777, bb_mode_string(newmode)+1);
}
return TRUE;
}
err:
if (!OPT_QUIET)
bb_simple_perror_msg(fileName);
return FALSE;
}
int chmod_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int chmod_main(int argc UNUSED_PARAM, char **argv)
{
int retval = EXIT_SUCCESS;
char *arg, **argp;
char *smode;
/* Convert first encountered -r into ar, -w into aw etc
* so that getopt would not eat it */
argp = argv;
while ((arg = *++argp)) {
/* Mode spec must be the first arg (sans -R etc) */
/* (protect against mishandling e.g. "chmod 644 -r") */
if (arg[0] != '-') {
arg = NULL;
break;
}
/* An option. Not a -- or valid option? */
if (arg[1] && !strchr("-"OPT_STR, arg[1])) {
arg[0] = 'a';
break;
}
}
/* Parse options */
getopt32(argv, "^" OPT_STR "\0" "-2");
argv += optind;
/* Restore option-like mode if needed */
if (arg) arg[0] = '-';
/* Ok, ready to do the deed now */
smode = *argv++;
do {
if (!recursive_action(*argv,
OPT_RECURSE, // recurse
fileAction, // file action
fileAction, // dir action
smode) // user data
) {
retval = EXIT_FAILURE;
}
} while (*++argv);
return retval;
}
/*
Security: chmod is too important and too subtle.
This is a test script (busybox chmod versus coreutils).
Run it in empty directory.
#!/bin/sh
t1="/tmp/busybox chmod"
t2="/usr/bin/chmod"
create() {
rm -rf $1; mkdir $1
(
cd $1 || exit 1
mkdir dir
>up
>file
>dir/file
ln -s dir linkdir
ln -s file linkfile
ln -s ../up dir/up
)
}
tst() {
(cd test1; $t1 $1)
(cd test2; $t2 $1)
(cd test1; ls -lR) >out1
(cd test2; ls -lR) >out2
echo "chmod $1" >out.diff
if ! diff -u out1 out2 >>out.diff; then exit 1; fi
rm out.diff
}
echo "If script produced 'out.diff' file, then at least one testcase failed"
create test1; create test2
tst "a+w file"
tst "a-w dir"
tst "a+w linkfile"
tst "a-w linkdir"
tst "-R a+w file"
tst "-R a-w dir"
tst "-R a+w linkfile"
tst "-R a-w linkdir"
tst "a-r,a+x linkfile"
*/