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
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.
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.Seecap_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.
This page is part of the libcap (capabilities commands and library)
project. Information about the project can be found at
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