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CentOS 7.0 - man page for cap_get_proc (centos section 3)

CAP_GET_PROC(3) 		    Linux Programmer's Manual			  CAP_GET_PROC(3)

NAME
       cap_get_proc,  cap_set_proc, capgetp, cap_get_bound, cap_drop_bound - capability manipula-
       tion on processes

SYNOPSIS
       #include <sys/capability.h>

       cap_t cap_get_proc(void);

       int cap_set_proc(cap_t cap_p);

       int cap_get_bound(cap_value_t cap);

       CAP_IS_SUPPORTED(cap_value_t cap);

       int cap_drop_bound(cap_value_t cap);

       #include <sys/types.h>

       cap_t cap_get_pid(pid_t pid);

       Link with -lcap.

DESCRIPTION
       cap_get_proc() allocates a capability state in working storage, sets its state to that  of
       the  calling  process,  and returns a pointer to this newly created capability state.  The
       caller should free any releasable memory, when the capability state in working storage  is
       no longer required, by calling cap_free() with the cap_t as an argument.

       cap_set_proc()  sets the values for all capability flags for all capabilities to the capa-
       bility state identified by cap_p.  The new capability state of the process  will  be  com-
       pletely determined by the contents of cap_p upon successful return from this function.  If
       any flag in cap_p is set for any  capability  not  currently  permitted	for  the  calling
       process,  the  function	will  fail,  and  the capability state of the process will remain
       unchanged.

       cap_get_pid() returns cap_d, see cap_init(3), with the process capabilities of the process
       indicated by pid.  This information can also be obtained from the /proc/<pid>/status file.

       cap_get_bound()	with  a cap as an argument returns the current value of this bounding set
       capability flag in effect for the current process. This operation is unpriveged.  Note,	a
       macro function CAP_IS_SUPPORTED(cap_value_t cap) is provided that evaluates to true (1) if
       the system supports the specified capability, cap.  If the system  does	not  support  the
       capability,  this  function  returns 0. This macro works by testing for an error condition
       with cap_get_bound().

       cap_drop_bound() can be used to lower the specified bounding set capability, cap, To  com-
       plete  successfully,  the prevailing effective capability set must have a raised CAP_SETP-
       CAP.

RETURN VALUE
       The functions cap_get_proc() and cap_get_pid() return a non-NULL  value	on  success,  and
       NULL on failure.

       The  function cap_get_bound() returns -1 if the requested capability is unknown, otherwise
       the return value reflects the current state of that capability in the prevailing  bounding
       set. Note, a macro function,

       The functions cap_set_proc() and cap_drop_bound() return zero for success, and -1 on fail-
       ure.

       On failure, errno is set to EINVAL, EPERM, or ENOMEM.

CONFORMING TO
       cap_set_proc() and cap_get_proc() are specified in the withdrawn POSIX.1e draft specifica-
       tion.  cap_get_pid() is a Linux extension.

NOTES
       The library also supports the deprecated functions:

       int capgetp(pid_t pid, cap_t cap_d);

       int capsetp(pid_t pid, cap_t cap_d);

       capgetp() attempts to obtain the capabilities of some other process; storing the capabili-
       ties in a pre-allocated cap_d.See cap_init() for information on allocating an empty  capa-
       bility set. This function, capgetp(), is deprecated, you should use cap_get_pid().

       capsetp() attempts to set the capabilities of some other process(es), pid.  If pid is pos-
       itive it refers to a specific process;  if it is zero, it refers to the	current  process;
       -1  refers  to  all  processes  other  than the current process and process '1' (typically
       init(8)); other negative values refer to the -pid process group.  In  order  to	use  this
       function,  the kernel must support it and the current process must have CAP_SETPCAP raised
       in its Effective capability set. The capabilities set in the target process(es) are  those
       contained  in  cap_d.  Kernels that support filesystem capabilities redefine the semantics
       of CAP_SETPCAP and on such systems this function will always fail for any target not equal
       to the current process.	capsetp() returns zero for success, and -1 on failure.

       Where  supported  by  the  kernel,  the	function  capsetp() should be used with care.  It
       existed, primarily, to overcome an early lack of support for capabilities in the  filesys-
       tems  supported by Linux.  Note that, by default, the only processes that have CAP_SETPCAP
       available to them are processes started as a  kernel  thread.   (Typically  this  includes
       init(8),  kflushd  and  kswapd).  You  will  need  to  recompile the kernel to modify this
       default.

EXAMPLE
       The code segment below raises the CAP_FOWNER and CAP_SETFCAP  effective	capabilities  for
       the caller:

	   cap_t caps;
	   cap_value_t cap_list[2];

	   if (!CAP_IS_SUPPORTED(CAP_SETFCAP))
	       /* handle error */

	   caps = cap_get_proc();
	   if (caps == NULL)
	       /* handle error */;

	   cap_list[0] = CAP_FOWNER;
	   cap_list[1] = CAP_SETFCAP;
	   if (cap_set_flag(caps, CAP_EFFECTIVE, 2, cap_list, CAP_SET) == -1)
	       /* handle error */;

	   if (cap_set_proc(caps) == -1)
	       /* handle error */;

	   if (cap_free(caps) == -1)
	       /* handle error */;

SEE ALSO
       libcap(3),  cap_clear(3), cap_copy_ext(3), cap_from_text(3), cap_get_file(3), cap_init(3),
       capabilities(7)

					    2008-05-11				  CAP_GET_PROC(3)


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