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busybox/libbb
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Daniel Thompson a818777d42 libbb: Enable support for !CONFIG_MULTIUSER 
Linux recently gained a new config option, CONFIG_MULTIUSER, that makes
support for non-root users optional. This results in a number of syscalls
being disabled: setuid, setregid, setgid, setreuid, setresuid, getresuid,
setresgid, getresgid, setgroups, getgroups, setfsuid, setfsgid, capget,
capset.

Currently a number of busybox applets, including login, struggle to run
when CONFIG_MULTIUSER is disabled. Even the root user is unable to login:
  login: can't set groups: Functi

This patch adds code to make change_identity() a nop on single user
systems. It works by recognising the signature errno value (ENOSYS, due
to the system calls being disabled) and, to avoid security risks, only
deploys when the current uid and target uid is the same.

After the patch is applied any attempt to switch to a non-root user will
fail. Thus a badly configured userspace (for example, one that tries to
start a daemon as a non-root user when the kernel cannot support this)
will report errors as one would expect.

Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2015-05-12 23:59:57 +02:00
..
appletlib.c special-case {true,false,test} --help 2015-04-21 16:00:41 +02:00
ask_confirmation.c
bb_askpass.c libbb: fix bb_ask() to flush input before prompt, not after. Closes 7190 2014-07-01 13:20:22 +02:00
bb_bswap_64.c *: deinline SWAP_xE64 on 32-bit CPUs. Wins !90 bytes both on 32 and 64 bits 2010-10-18 11:40:26 +02:00
bb_do_delay.c
bb_pwd.c libpwdgrp: rewritten to use malloced implementation 2015-01-02 21:37:59 +01:00
bb_qsort.c
bb_strtod.c
bb_strtonum.c libbb/bb_strtonum: always set end ptr, even on error return 2011-12-22 13:00:32 +01:00
bbunit.c bbunit: fix WANT_TIMING compilation 2014-11-26 14:04:51 +01:00
change_identity.c libbb: Enable support for !CONFIG_MULTIUSER 2015-05-12 23:59:57 +02:00
chomp.c
compare_string_array.c libbb: introduce and use is_prefixed_with() 2015-03-12 17:48:34 +01:00
concat_path_file.c
concat_subpath_file.c
Config.src sha3: make size/speed optimization decision configurable 2013-01-15 01:12:26 +01:00
copy_file.c Add conditional support for -v / --verbose 2014-05-19 16:23:50 +02:00
copyfd.c libbb: use sendfile() to copy data between file descriptors 2014-11-27 23:31:58 +01:00
correct_password.c ftpd: add optional support for authentication 2014-08-05 21:57:18 +02:00
crc32.c whitespace fixes 2011-02-03 00:05:48 +01:00
default_error_retval.c
device_open.c
die_if_bad_username.c die_if_bad_username: tighten up a bit 2011-08-09 04:05:13 +02:00
dump.c hexdump: don't unconditionally limit the usable address range 2013-03-27 15:15:33 +01:00
endofname.c move endofname() to libbb 2013-02-26 00:36:53 +01:00
executable.c libbb: rename execable -> executable. No code changes 2014-05-02 17:15:58 +02:00
fclose_nonstdin.c sed: open input files sequentially to avoid EMFILE 2013-11-28 03:14:16 +01:00
fflush_stdout_and_exit.c
fgets_str.c
find_mount_point.c find_mount_point: fix find_mount_point for char devices 2012-01-18 01:49:11 +01:00
find_pid_by_name.c
find_root_device.c plug a DIR* leak on error path 2010-12-28 10:25:03 +01:00
full_write.c *: whitespace fixes 2010-10-28 18:57:19 +02:00
get_console.c
get_cpu_count.c
get_last_path_component.c find: cater for libc w/o FNM_CASEFOLD 2011-05-23 00:40:54 +02:00
get_line_from_file.c libbb: split bb_get_chunk_from_file and bb_get_chunk_with_continuation 2011-06-17 03:37:43 +02:00
get_shell_name.c mark get_shell_name FAST_FUNC 2012-10-03 09:42:21 +02:00
get_volsize.c
getopt32.c randomconfig fixes 2011-08-10 00:51:29 +02:00
getpty.c script: make it work even if fd 0 is closed 2014-03-16 12:34:53 +01:00
hash_md5_sha.c sha3: tweak comments and indentation 2014-07-30 16:26:09 +02:00
hash_md5prime.c regularize options which control size/speed trade 2011-09-10 13:25:57 +02:00
herror_msg.c
human_readable.c Make smart_ulltoa return pointer to end (allows for code shink in callers) 2013-09-06 12:53:14 +02:00
in_ether.c fix failures found by randomconfig builds 2013-12-31 23:22:36 +01:00
inet_cksum.c inet_cksum: big-endian fix 2011-09-08 10:59:26 +02:00
inet_common.c libbb: make INET[6]_rresolve use sockaddr2{host,dotted}_noport 2015-02-03 12:07:40 +01:00
info_msg.c
inode_hash.c du, copy_file: fix file matching on cramfs. Closes 5456 2014-02-25 15:27:58 +01:00
isdirectory.c libbb: remove is_directory's argument which is always NULL 2011-12-18 03:27:46 +01:00
Kbuild.src randomconfig fixes 2014-12-22 19:37:05 +01:00
kernel_version.c get_linux_version_code: don't fail on Linux version strints like "3.0-foo" 2012-05-05 17:47:23 +02:00
last_char_is.c
lineedit_ptr_hack.c
lineedit.c libbb: introduce and use is_prefixed_with() 2015-03-12 17:48:34 +01:00
llist.c main: free suid_config list after use 2011-05-16 12:21:31 +02:00
logenv.c zcip: Add environment variable for overriding log functionality 2014-11-04 12:19:04 +01:00
login.c libbb: introduce and use strftime_[YYYYMMDD]HHMMSS() 2013-03-29 12:30:33 +01:00
loop.c libbb/loop: don't try to re-use existing loop device 2015-02-07 19:13:57 +01:00
make_directory.c Add conditional support for -v / --verbose 2014-05-19 16:23:50 +02:00
makedev.c nicer looking ifdef in libbb/makedev.c 2011-01-24 23:53:12 +01:00
match_fstype.c libbb: introduce and use is_prefixed_with() 2015-03-12 17:48:34 +01:00
messages.c save 10 bytes on strings 2011-02-10 10:01:49 +01:00
missing_syscalls.c Bionic lacks tcdrain; provide a workaround 2015-04-26 13:14:50 +02:00
mode_string.c
mtab.c
nuke_str.c fix failures found by randomconfig builds 2013-12-31 23:22:36 +01:00
obscure.c unit-tests: implement the unit-testing framework 2014-06-22 16:30:41 +02:00
parse_config.c mdev: do not treat non-leading '#' chars as start of comment. Closes 4676 2012-01-11 00:37:17 +01:00
parse_mode.c *: whitespace fixes 2010-10-28 18:57:19 +02:00
percent_decode.c wget: URL-decode user:password before base64-encoding it into auth hdr. Closes 3625. 2011-09-11 21:04:02 +02:00
perror_msg.c
perror_nomsg_and_die.c
perror_nomsg.c
pidfile.c
platform.c Bionic lacks ttyname_r; provide a workaround 2015-04-25 21:32:48 +02:00
print_flags.c
printable_string.c
printable.c Refactor catv. Move visible() from stty to libbb. 2013-07-30 06:29:42 +02:00
process_escape_sequence.c libbb/process_escape_sequence.c: fix recently broken handling of \\ 2010-10-25 12:14:21 +02:00
procps.c libbb: introduce and use is_prefixed_with() 2015-03-12 17:48:34 +01:00
progress.c libbb: make warning go away 2011-03-12 02:19:50 +01:00
ptr_to_globals.c
pw_encrypt_des.c
pw_encrypt_md5.c fix assorted unused code and wrong format specs found by cppchekc (bug 6716) 2013-11-29 16:43:33 +01:00
pw_encrypt_sha.c libbb/pw_encrypt_sha: forgot to move &ctx to 1st param here in sha hash rework 2010-12-01 13:57:25 +01:00
pw_encrypt.c libbb: don't die if crypt() returns NULL 2014-02-09 14:38:03 +01:00
read_key.c Add comments in keyboard escape sequences table 2012-06-11 14:40:17 +02:00
read_printf.c libbb: remove unnecessary argument to nonblock_immune_read 2015-04-20 13:41:32 +02:00
read.c
README
recursive_action.c
remove_file.c Add conditional support for -v / --verbose 2014-05-19 16:23:50 +02:00
replace.c xargs: add support for -I and -i. Closes 493 2014-02-27 11:17:06 +01:00
rtc.c libbb: introduce and use is_prefixed_with() 2015-03-12 17:48:34 +01:00
run_shell.c
safe_gethostname.c sendmail: use host rather than NIS domain name for HELO 2012-04-28 17:04:19 +02:00
safe_poll.c
safe_strncpy.c klogd: do not log partial lines 2010-10-19 23:07:49 +02:00
safe_write.c
selinux_common.c whitespace cleanup. no code changes 2013-01-14 15:57:44 +01:00
setup_environment.c su: do not change to home dir unless -l 2012-06-12 13:21:02 +02:00
signals.c libbb: correctness/size tweaks in signal-related helpers 2012-09-27 13:20:34 +02:00
simplify_path.c whitespace cleanup 2010-10-29 11:46:52 +02:00
single_argv.c basename,dirname,freeramdisk,rx,raidautorun,runsv,chvt: skip "--" argument 2011-04-11 03:58:30 +02:00
skip_whitespace.c libbb: introduce and use is_prefixed_with() 2015-03-12 17:48:34 +01:00
speed_table.c libbb: FreeBSD fix for B<num> baud rate constants not fitting into a short. 2014-01-08 15:25:20 +01:00
str_tolower.c
strrstr.c unit-tests: implement the unit-testing framework 2014-06-22 16:30:41 +02:00
sysconf.c libbb: add sanity check in bb_arg_max() 2014-12-24 01:46:29 +01:00
systemd_support.c typo fix 2011-02-12 01:56:25 +01:00
time.c libbb: fix parsing of "10101010" date/time form 2014-01-21 07:58:18 +01:00
trim.c
u_signal_names.c kill[all[5]],pkill: make signal list show signal numbers, and show RTMIN/MAX 2011-01-03 13:08:58 +01:00
udp_io.c Fixes for warnings in FreeBSD build 2011-08-28 05:31:49 +02:00
unicode.c lineedit: improve Unicode handling (still buggy though) 2013-08-19 16:44:05 +02:00
update_passwd.c libbb: introduce and use is_prefixed_with() 2015-03-12 17:48:34 +01:00
utmp.c *: Switch to POSIX utmpx API 2015-04-02 23:03:46 +02:00
uuencode.c libbb: shrink base64 decoding a bit 2011-10-28 16:15:00 +02:00
vdprintf.c libbb.h: remove unused defines 2011-10-24 04:06:18 +02:00
verror_msg.c Fix compile failures 2014-05-02 07:18:55 +02:00
vfork_daemon_rexec.c bb_daemonize_or_rexec(): add flag to double-fork; use it in start-stop-daemon 2011-11-09 19:44:37 +01:00
warn_ignoring_args.c
wfopen_input.c *: whitespace fixes 2010-10-28 18:57:19 +02:00
wfopen.c
write.c
xatonum_template.c whitespace fixes. no code changes 2013-01-15 13:58:01 +01:00
xatonum.c truncate: new applet 2015-03-22 17:56:38 +01:00
xconnect.c libbb: introduce and use is_prefixed_with() 2015-03-12 17:48:34 +01:00
xfunc_die.c
xfuncs_printf.c libbb: Add xsetegid(), xseteuid(), xopen_as_uid_gid() functions 2013-10-08 14:52:49 +02:00
xfuncs.c less: move "retry-on-EAGAIN" logic closer to read ops 2014-09-22 21:14:02 +02:00
xgetcwd.c *: whitespace fixes 2010-10-28 18:57:19 +02:00
xgethostbyname.c
xreadlink.c libbb: fix a bad check for uclibc >= 0.9.31 2014-03-16 20:53:40 +01:00
xrealloc_vector.c
xregcomp.c

README 

Please see the LICENSE file for copyright information (GPLv2)

libbb is BusyBox's utility library.  All of this stuff used to be stuffed into
a single file named utility.c.  When I split utility.c to create libbb, some of
the very oldest stuff ended up without their original copyright and licensing
information (which is now lost in the mists of time).  If you see something
that you wrote that is mis-attributed, do let me know so we can fix that up.

	Erik Andersen
	<andersen@codepoet.org>