CAPSH(1)							   User Commands							  CAPSH(1)

NAME

       capsh - capability shell wrapper

SYNOPSIS

       capsh [OPTION]...

DESCRIPTION

       Linux  capability  support  and use can be explored and constrained with this tool. This tool provides a handy wrapper for certain types of
       capability testing and environment creation. It also provides some debugging features useful for summarizing capability state.

OPTIONS

       The tool takes a number of optional arguments, acting on them in the order they are provided. They are as follows:

       --print		     Display prevailing capability and related state.

       -- [args]	     Execute /bin/bash with trailing arguments. Note, you can use -c 'command to execute' for specific commands.

       ==		     Execute capsh again with remaining arguments. Useful for testing exec() behavior.

       --caps=cap-set	     Set the prevailing process capabilities to those specified by cap-set.  Where cap-set  is	a  text-representation	of
			     capability state as per cap_from_text(3).

       --drop=cap-list	     Remove the listed capabilities from the prevailing bounding set. The capabilities are a comma separated list of capa-
			     bilities as recognized by the cap_from_name(3) function. Use of this feature requires that the capsh program is oper-
			     ating with CAP_SETPCAP in its effective set.

       --inh=cap-list	     Set  the inheritable set of capabilities for the current process to equal those provided in the comma separated list.
			     For this action to succeed, the prevailing process should already have each of these capabilities in the union of the
			     current  inheritable  and permitted capability sets, or the capsh program is operating with CAP_SETPCAP in its effec-
			     tive set.

       --user=username	     Assume the identity of the named user. That is, look up the user's uid and gid with getpwuid(3) and their group  mem-
			     berships with getgrouplist(3) and set them all.

       --uid=id 	     Force all uid values to equal id using the setuid(2) system call.

       --gid=<id>	     Force all gid values to equal id using the setgid(2) system call.

       --groups=<id-list>    Set the supplementary groups to the numerical list provided. The groups are set with the setgroups(2) system call.

       --keep=<0|1>	     In  a  non-pure capability mode, the kernel provides liberal privilege to the super-user. However, it is normally the
			     case that when the super-user changes uid to some lesser user, then capabilities are dropped. For	these  situations,
			     the  kernel can permit the process to retain its capabilities after a setuid(2) system call. This feature is known as
			     keep-caps support. The way to activate it using this script is with this argument. Setting the value to 1 will  cause
			     keep-caps	to  be	active.  Setting it to 0 will cause keep-caps to deactivate for the current process. In all cases,
			     keep-caps is deactivated when an exec() is performed. See --secbits for ways to disable this feature.

       --secbits=N	     XXX - need to document this feature.

       --chroot=path	     Execute the chroot(2) system  call  with  the  new  root-directory  (/)  equal  to  path.	 This  operation  requires
			     CAP_SYS_CHROOT to be in effect.

       --forkfor=sec

       --killit=sig

       --decode=N	     This  is a convenience feature. If you look at /proc/1/status there are some capability related fields of the follow-
			     ing form:

			      CapInh:  0000000000000000
			      CapPrm:  ffffffffffffffff
			      CapEff:  fffffffffffffeff
			      CapBnd:  ffffffffffffffff

			     This option provides a quick way to decode a capability vector represented in this form.  For  example,  the  missing
			     capability from this effective set is 0x0100. By running:

			      capsh --decode=0x0100

			     we observe that the missing capability is: cap_setpcap.

       --supports=xxx	     As  the  kernel evolves, more capabilities are added. This option can be used to verify the existence of a capability
			     on the system. For example, --supports=cap_syslog will cause capsh to promptly exit with a status of 1  when  run	on
			     kernel 2.6.27.  However, when run on kernel 2.6.38 it will silently succeed.

       EXIT STATUS
	      Following successful execution the tool exits with status 0. Following an error, the tool immediately exits with status 1.

AUTHOR

       Written by Andrew G. Morgan <morgan@kernel.org>.

REPORTING BUGS

       Please report bugs to the author.

SEE ALSO

       libcap(3), getcap(8),setcap(8) and capabilities(7).

libcap 2							    2011-04-24								  CAPSH(1)