If a jail has an explicitly assigned loopback address then allow it to be
used instead of remapping requests for the loopback adddress to the first
IPv4 address assigned to the jail.
This fixes issues where applications attempt to detect their bound port
where they requested a loopback address, which was available, but instead
the kernel remapped it to the jails first address.
A example of this is binding nginx to 127.0.0.1 and then running "service
nginx upgrade" which before this change would cause nginx to fail.
Also:
* Correct the description of prison_check_ip4_locked to match the code.
MFC after: 2 weeks
Relnotes: Yes
Sponsored by: Multiplay
_prison_check_ip4 renamed to prison_check_ip4_locked
Move IPv6-specific jail functions to new file netinet6/in6_jail.c
_prison_check_ip6 renamed to prison_check_ip6_locked
Add appropriate prototypes to sys/sys/jail.h
Adjust kern_jail.c to call prison_check_ip4_locked and
prison_check_ip6_locked accordingly.
Add netinet/in_jail.c and netinet6/in6_jail.c to the list of files that
need to be built when INET and INET6, respectively, are configured in the
kernel configuration file.
Reviewed by: jtl
Approved by: sjg (mentor)
Sponsored by: Juniper Networks, Inc.
Differential Revision: https://reviews.freebsd.org/D6799
