xref: /external/ltp/testcases/kernel/security/filecaps

POSIX capabilities are pieces of root privilege, for instance
CAP_SYS_NICE to set priority on other tasks and CAP_SYS_TIME
to set system time.  See
http://www.kernel.org/pub/linux/libs/security/linux-privs/kernel-2.4/capfaq-0.2.txt
for more information.

A task's capabilities are set when it executes a new file, and
when it explicitly changes them (see capset(2)).  After exec,
the task's new capabilities are a function of its previous
capabilities and the file's capabilities:

	pI' = pI
	pP' = fP | (fI & pI)
	pE' = fE ? pP' : 0

Where pX is capability set X for process p before exec, pX' is
capability set X for process P after exec and fX is file
capability set X.  The capability sets are I for inheritable,
P for permitted, and E for effective.  Note that fE is a
boolean rather than a set.

File capabilities are stored in extended attributes named
'security.capability.'  Setting this xattr requires the
CAP_SETFCAP capability when the capability security module is
loaded, or CAP_SYS_ADMIN when it is not.

The following tests are implemented here:

inh_capped: check whether a process without CAP_SETPCAP
	is properly prohibited from raising bits in its
	inheritable set using setcap.

verify_caps_exec:
	1. check that privilege is needed to set file capabilities
	2. check that pI', pP', and pE' are properly
	   calculated upon exec.
The Underlying kernel needs to be built with the following options for filecaps testing:
CONFIG_SECURITY_CAPABILITIES=y