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
       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 capability state identified by cap_p.  The new
       capability 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_t, 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 complete successfully, the prevailing effective
       capability 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
       success, 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
       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 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)