.TH "seccomp_api_get" 3 "6 November 2020" "paul@paul-moore.com" "libseccomp Documentation"
.\" //////////////////////////////////////////////////////////////////////////
.SH NAME
.\" //////////////////////////////////////////////////////////////////////////
seccomp_api_get, seccomp_api_set \- Manage the libseccomp API level
.\" //////////////////////////////////////////////////////////////////////////
.SH SYNOPSIS
.\" //////////////////////////////////////////////////////////////////////////
.nf
.B #include <seccomp.h>
.sp
.BI "const unsigned int seccomp_api_get(" void ");"
.BI "int seccomp_api_set(unsigned int " level ");"
.sp
Link with \fI\-lseccomp\fP.
.fi
.\" //////////////////////////////////////////////////////////////////////////
.SH DESCRIPTION
.\" //////////////////////////////////////////////////////////////////////////
.P
The
.BR seccomp_api_get ()
function returns an integer representing the functionality ("API level")
provided by the current running kernel.  It is important to note that while
.BR seccomp_api_get ()
can be called multiple times, the kernel is only probed the first time to see
what functionality is supported, all following calls to
.BR seccomp_api_get ()
return a cached value.
.P
The
.BR seccomp_api_set ()
function allows callers to force the API level to the provided value; however,
this is almost always a bad idea and use of this function is strongly
discouraged.
.P
The different API level values are described below:
.TP
.B 0
Reserved value, not currently used.
.TP
.B 1
Base level support.
.TP
.B 2
The SCMP_FLTATR_CTL_TSYNC filter attribute is supported and libseccomp uses
the
.BR seccomp(2)
syscall to load the seccomp filter into the kernel.
.TP
.B 3
The SCMP_FLTATR_CTL_LOG filter attribute and the SCMP_ACT_LOG action are
supported.
.TP
.B 4
The SCMP_FLTATR_CTL_SSB filter attribute is supported.
.TP
.B 5
The SCMP_ACT_NOTIFY action and the notify APIs are supported.
.TP
.B 6
The simultaneous use of SCMP_FLTATR_CTL_TSYNC and the notify APIs are supported.
.\" //////////////////////////////////////////////////////////////////////////
.SH RETURN VALUE
.\" //////////////////////////////////////////////////////////////////////////
The
.BR seccomp_api_get ()
function returns an integer representing the supported API level.  The
.BR seccomp_api_set ()
function returns zero on success, negative values on failure.
.\" //////////////////////////////////////////////////////////////////////////
.SH EXAMPLES
.\" //////////////////////////////////////////////////////////////////////////
.nf
#include <seccomp.h>

int main(int argc, char *argv[])
{
	unsigned int api;

	api = seccomp_api_get();
	switch (api) {
	case 2:
		/* ... */
	default:
		/* ... */
	}

	return 0;

err:
	return 1;
}
.fi
.\" //////////////////////////////////////////////////////////////////////////
.SH NOTES
.\" //////////////////////////////////////////////////////////////////////////
.P
While the seccomp filter can be generated independent of the kernel, kernel
support is required to load and enforce the seccomp filter generated by
libseccomp.
.P
The libseccomp project site, with more information and the source code
repository, can be found at https://github.com/seccomp/libseccomp.  This tool,
as well as the libseccomp library, is currently under development, please
report any bugs at the project site or directly to the author.
.\" //////////////////////////////////////////////////////////////////////////
.SH AUTHOR
.\" //////////////////////////////////////////////////////////////////////////
Paul Moore <paul@paul-moore.com>
.\" //////////////////////////////////////////////////////////////////////////