centos man page for sk_chk_filter

SK_CHK_FILTER(9)						 Linux Networking						  SK_CHK_FILTER(9)

NAME
       sk_chk_filter - verify socket filter code

SYNOPSIS
       int sk_chk_filter(struct sock_filter * filter, unsigned int flen);

ARGUMENTS
       filter
	   filter to verify

       flen
	   length of filter

DESCRIPTION
       Check the user's filter code. If we let some ugly filter code slip through kaboom! The filter must contain no references or jumps that are
       out of range, no illegal instructions, and must end with a RET instruction.

       All jumps are forward as they are not signed.

       Returns 0 if the rule set is legal or -EINVAL if not.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014							  SK_CHK_FILTER(9)