int cap_set_proc(cap_t cap_p);
cap_t cap_get_pid(pid_t pid);
Link with -lcap.
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.
The function cap_set_proc() return zero for success, and -1 on failure.
On failure, errno is set to EINVAL, EPERM, or ENOMEM.
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.
cap_t caps; cap_value_t cap_list; caps = cap_get_proc(); if (caps == NULL) /* handle error */; cap_list = CAP_FOWNER; cap_list = 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 */;