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



NAME
       cap_get_proc, cap_set_proc, capgetp - capability manipulation on processes

SYNOPSIS
       #include <sys/capability.h>

       cap_t cap_get_proc(void);

       int cap_set_proc(cap_t cap_p);

       #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 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_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.

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_set_proc() return zero for success, and -1 on failure.

       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       cap_set_proc()  and  cap_get_proc() are specified in the withdrawn POSIX.1e draft specification.  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 capabilities  in  a  pre-allo-
       cated  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.

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];

           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)