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

       cap_get_proc,  cap_set_proc,  capgetp,  cap_get_bound, cap_drop_bound -
       capability manipulation on processes

       #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.

       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 re-
       quired, by calling cap_free() with the cap_t as an argument.

       cap_set_proc() sets the values for all capability flags for  all	 capa-
       bilities	to the capability state	identified by cap_p.  The new capabil-
       ity state of the	process	will be	completely 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 capabil-
       ities  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_SUP-
       PORTED(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	 capa-
       bility,	cap,  To complete successfully,	the prevailing effective capa-
       bility set must have a raised CAP_SETPCAP.

       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 suc-
       cess, and -1 on failure.

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

       cap_set_proc()  and  cap_get_proc()  are	 specified  in	the  withdrawn
       POSIX.1e	draft specification.  cap_get_pid() is a Linux extension.

       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 capabilities	in a pre-allocated  cap_d.See  cap_init()  for
       information  on	allocating  an	empty  capability  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  positive 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  capabili-
       ties  set in the	target process(es) are those contained in cap_d.  Ker-
       nels 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	filesystems 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.

       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];

	       /* 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 */;

       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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