[prev in list] [next in list] [prev in thread] [next in thread] 

List:       busybox
Subject:    Re: [PATCH v2] setpriv: new applet
From:       Tito <farmatito () tiscali ! it>
Date:       2017-05-14 19:44:42
Message-ID: d0dc311b-f918-bbbb-0893-351c919442e2 () tiscali ! it
[Download RAW message or body]

Hi,
just some hints to shrink the code.

Ciao,
Tito

On 05/14/2017 02:46 PM, Assaf Gordon wrote:
> Add a minimal 'setpriv' implementation supporting the NO_NEW_PRIVS bit.
> As upstream only supports long options (--nnp/--no-new-privs),
> A non-standard "-N" option is also added for the applet.
> 
> Typical usage:
> 
> $ busybox setpriv sudo uname
> Linux
> $ busybox setpriv --nnp sudo uname
> sudo: effective uid is not 0, is /usr/bin/sudo on a file system with
> the 'nosuid' option set or an NFS file system without root privileges?
> 
> Signed-off-by: Assaf Gordon <assafgordon@gmail.com>
> ---
> 
> Hello,
> This patch is a minor fix for parameter handling (detecting when the
> program parameter is missing).
> Description for 'setpriv' here:
> http://lists.busybox.net/pipermail/busybox/2017-May/085448.html
> 
> util-linux/setpriv.c | 90 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 90 insertions(+)
> create mode 100644 util-linux/setpriv.c
> 
> diff --git a/util-linux/setpriv.c b/util-linux/setpriv.c
> new file mode 100644
> index 0000000..999c9b8
> --- /dev/null
> +++ b/util-linux/setpriv.c
> @@ -0,0 +1,90 @@
> +/* vi: set sw=4 ts=4: */
> +/*
> + * setpriv implementation for busybox based on linux-utils-ng 2.29
> + *
> + * Copyright (C) 2017 by  <assafgordon@gmail.com>
> + *
> + * Licensed under GPLv2 or later, see file LICENSE in this source tree.
> + *
> + */
> +//config:config SETPRIV
> +//config:	bool "setpriv"
> +//config:	default y
> +//config:	select PLATFORM_LINUX
> +//config:	help
> +//config:	  run a program with different Linux privilege settings
> +//config:	  currently only --no-new-privs is supported
> +//config:	  Requires kernel >= 3.5
> +//config:
> +//config:config FEATURE_SETPRIV_LONG_OPTS
> +//config:	bool "Enable long options"
> +//config:	default y
> +//config:	depends on SETPRIV && LONG_OPTS
> +//config:	help
> +//config:	  Support long options for the setpriv applet. This makes
> +//config:	  the busybox implementation more compatible with upstream.
> +
> +//applet:IF_SETPRIV(APPLET(setpriv, BB_DIR_BIN, BB_SUID_DROP))
> +
> +//kbuild:lib-$(CONFIG_SETPRIV) += setpriv.o
> +
> +//usage:#if ENABLE_FEATURE_SETPRIV_LONG_OPTS
> +//usage:#define setpriv_trivial_usage
> +//usage:	"[-N|--nnp|--no-new-privs] PROG [ARGS]"
> +//usage:#define setpriv_full_usage "\n\n"
> +//usage:       "run a program with different Linux privilege settings\n"
> +//usage:     "\n-N,--nnp,--no-new-privs	 Set the no_new_privs bit\n"
> +//usage:#define setpriv_example_usage
> +//usage:       "$ setpriv --nnp my-program"
> +//usage:#else
> +//usage:#define setpriv_trivial_usage
> +//usage:	"[-N] PROG [ARGS]"
> +//usage:#define setpriv_full_usage "\n\n"
> +//usage:       "run a program with different Linux privilege settings\n"
> +//usage:     "\n-N	 Set the no_new_privs bit\n"
> +//usage:#define setpriv_example_usage
> +//usage:       "$ setpriv -N my-program"
> +//usage:#endif
> +
> +#include <sys/syscall.h>
> +#include <sys/prctl.h>
> +#include <asm/unistd.h>
> +#include "libbb.h"
> +
> +
> +enum {
> +	OPT_nnp	= 1 << 0
> +};
> +
> +/*
> + * Upstream setpriv doesn't support the short option for --nnp/--no-new-privs.
> + * Invent new short-option 'N'
> + */
> +static const char opt_str[] ALIGN1 = "N";
> +
> +#if ENABLE_FEATURE_SETPRIV_LONG_OPTS
> +static const char setpriv_longopts[] ALIGN1 =
> +	"nnp\0"				No_argument	"N"
> +	"no-new-privs\0"	No_argument	"N"
> +;
> +#endif
> +
> +int setpriv_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
> +int setpriv_main(int argc UNUSED_PARAM, char **argv)
> +{
> +	unsigned int opts;

       "-N"   A dash as the first char in a opt_complementary group
        followed by a single digit (0-9) means that at least N
        non-option arguments must be present on the command line 

 	opt_complementary = "-1";
> +
> +	IF_FEATURE_SETPRIV_LONG_OPTS(applet_long_options = setpriv_longopts);
> +	opts = getopt32(argv, opt_str);
> +	argv += optind;
> +
> +	
	If opt_complementary -1 is used this check could be removed. 
        /* after getopt32, argv[0] is the name of the program to execute */
> +	if (!argv[0])
> +		bb_show_usage();
> +
> +	if (opts & OPT_nnp)
> +		if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0))                                      \
>  +			bb_simple_perror_msg_and_die("prctl(): failed to NO_NEW_PRIVS");
			bb_simple_perror_msg_and_die("prctl");
or 
                        bb_simple_perror_msg_and_die("NO_NEW_PRIVS");
or
                        bb_simple_perror_msg_and_die("prctl: NO_NEW_PRIVS"); 
could save some space                       
> +
> +	BB_EXECVP_or_die(argv);
> +}
> 

if you don't plan to add other options you could drop the enum and do (untested):

int setpriv_main(int argc UNUSED_PARAM, char **argv)
{
 	opt_complementary = "-1";

	IF_FEATURE_SETPRIV_LONG_OPTS(applet_long_options = setpriv_longopts);
	if (getopt32(argv, opt_str))
                if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0))                           \
  bb_simple_perror_msg_and_die("prctl");
	argv += optind;
        BB_EXECVP_or_die(argv);
}
_______________________________________________
busybox mailing list
busybox@busybox.net
http://lists.busybox.net/mailman/listinfo/busybox


[prev in list] [next in list] [prev in thread] [next in thread]