treewide: replace '---help---' in Kconfig files with 'help'

Since commit 84af7a6194e4 ("checkpatch: kconfig: prefer 'help' over
'---help---'"), the number of '---help---' has been gradually
decreasing, but there are still more than 2400 instances.

This commit finishes the conversion. While I touched the lines,
I also fixed the indentation.

There are a variety of indentation styles found.

a) 4 spaces + '---help---'
b) 7 spaces + '---help---'
c) 8 spaces + '---help---'
d) 1 space + 1 tab + '---help---'
e) 1 tab + '---help---' (correct indentation)
f) 1 tab + 1 space + '---help---'
g) 1 tab + 2 spaces + '---help---'

In order to convert all of them to 1 tab + 'help', I ran the
following commend:

$ find . -name 'Kconfig*' | xargs sed -i 's/^[[:space:]]*---help---/\thelp/'

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

treewide: Add SPDX license identifier - Makefile/Kconfig

Add SPDX license identifiers to all Make/Kconfig files which:

- Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

l2tp: Call udp_sock_create

In l2tp driver call common function udp_sock_create to create the
listener UDP port.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/l2tp: remove depends on CONFIG_EXPERIMENTAL

The CONFIG_EXPERIMENTAL config item has not carried much meaning for a
while now and is almost always enabled by default. As agreed during the
Linux kernel summit, remove it from any "depends on" lines in Kconfigs.

CC: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: David S. Miller <davem@davemloft.net>

l2tp: fix compile error when CONFIG_IPV6=m and CONFIG_L2TP=y

When CONFIG_IPV6=m and CONFIG_L2TP=y, I got the following compile error:

LD init/built-in.o
net/built-in.o: In function `l2tp_xmit_core':
l2tp_core.c:(.text+0x147781): undefined reference to `inet6_csk_xmit'
net/built-in.o: In function `l2tp_tunnel_create':
(.text+0x149067): undefined reference to `udpv6_encap_enable'
net/built-in.o: In function `l2tp_ip6_recvmsg':
l2tp_ip6.c:(.text+0x14e991): undefined reference to `ipv6_recv_error'
net/built-in.o: In function `l2tp_ip6_sendmsg':
l2tp_ip6.c:(.text+0x14ec64): undefined reference to `fl6_sock_lookup'
l2tp_ip6.c:(.text+0x14ed6b): undefined reference to `datagram_send_ctl'
l2tp_ip6.c:(.text+0x14eda0): undefined reference to `fl6_sock_lookup'
l2tp_ip6.c:(.text+0x14ede5): undefined reference to `fl6_merge_options'
l2tp_ip6.c:(.text+0x14edf4): undefined reference to `ipv6_fixup_options'
l2tp_ip6.c:(.text+0x14ee5d): undefined reference to `fl6_update_dst'
l2tp_ip6.c:(.text+0x14eea3): undefined reference to `ip6_dst_lookup_flow'
l2tp_ip6.c:(.text+0x14eee7): undefined reference to `ip6_dst_hoplimit'
l2tp_ip6.c:(.text+0x14ef8b): undefined reference to `ip6_append_data'
l2tp_ip6.c:(.text+0x14ef9d): undefined reference to `ip6_flush_pending_frames'
l2tp_ip6.c:(.text+0x14efe2): undefined reference to `ip6_push_pending_frames'
net/built-in.o: In function `l2tp_ip6_destroy_sock':
l2tp_ip6.c:(.text+0x14f090): undefined reference to `ip6_flush_pending_frames'
l2tp_ip6.c:(.text+0x14f0a0): undefined reference to `inet6_destroy_sock'
net/built-in.o: In function `l2tp_ip6_connect':
l2tp_ip6.c:(.text+0x14f14d): undefined reference to `ip6_datagram_connect'
net/built-in.o: In function `l2tp_ip6_bind':
l2tp_ip6.c:(.text+0x14f4fe): undefined reference to `ipv6_chk_addr'
net/built-in.o: In function `l2tp_ip6_init':
l2tp_ip6.c:(.init.text+0x73fa): undefined reference to `inet6_add_protocol'
l2tp_ip6.c:(.init.text+0x740c): undefined reference to `inet6_register_protosw'
net/built-in.o: In function `l2tp_ip6_exit':
l2tp_ip6.c:(.exit.text+0x1954): undefined reference to `inet6_unregister_protosw'
l2tp_ip6.c:(.exit.text+0x1965): undefined reference to `inet6_del_protocol'
net/built-in.o:(.rodata+0xf2d0): undefined reference to `inet6_release'
net/built-in.o:(.rodata+0xf2d8): undefined reference to `inet6_bind'
net/built-in.o:(.rodata+0xf308): undefined reference to `inet6_ioctl'
net/built-in.o:(.data+0x1af40): undefined reference to `ipv6_setsockopt'
net/built-in.o:(.data+0x1af48): undefined reference to `ipv6_getsockopt'
net/built-in.o:(.data+0x1af50): undefined reference to `compat_ipv6_setsockopt'
net/built-in.o:(.data+0x1af58): undefined reference to `compat_ipv6_getsockopt'
make: *** [vmlinux] Error 1

This is due to l2tp uses symbols from IPV6, so when IPV6
is a module, l2tp is not allowed to be builtin.

Cc: David Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

l2tp: Add debugfs files for dumping l2tp debug info

The existing pppol2tp driver exports debug info to
/proc/net/pppol2tp. Rather than adding info to that file for the new
functionality added in this patch series, we add new files in debugfs,
leaving the old /proc file for backwards compatibility (L2TPv2 only).

Currently only one file is provided: l2tp/tunnels, which lists
internal debug info for all l2tp tunnels and sessions. More files may
be added later. The info is for debug and problem analysis only -
userspace apps should use netlink to obtain status about l2tp tunnels
and sessions.

Although debugfs does not support net namespaces, the tunnels and
sessions dumped in l2tp/tunnels are only those in the net namespace of
the process reading the file.

Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

l2tp: Add L2TP ethernet pseudowire support

This driver presents a regular net_device for each L2TP ethernet
pseudowire instance. These interfaces are named l2tpethN by default,
though userspace can specify an alternative name when the L2TP
session is created, if preferred. When the pseudowire is established,
regular Linux networking utilities may be used to configure the
interface, i.e. give it IP address info or add it to a bridge. Any
data passed over the interface is carried over an L2TP tunnel.

Signed-off-by: James Chapman <jchapman@katalix.com>
Reviewed-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

l2tp: Add L2TPv3 IP encapsulation (no UDP) support

This patch adds a new L2TPIP socket family and modifies the core to
handle the case where there is no UDP header in the L2TP
packet. L2TP/IP uses IP protocol 115. Since L2TP/UDP and L2TP/IP
packets differ in layout, the datapath packet handling code needs
changes too. Userspace uses an L2TPIP socket instead of a UDP socket
when IP encapsulation is required.

We can't use raw sockets for this because the semantics of raw sockets
don't lend themselves to the socket-per-tunnel model - we need to

Signed-off-by: David S. Miller <davem@davemloft.net>

l2tp: Add L2TPv3 protocol support

The L2TPv3 protocol changes the layout of the L2TP packet
header. Tunnel and session ids change from 16-bit to 32-bit values,
data sequence numbers change from 16-bit to 24-bit values and PPP-specific
fields are moved into protocol-specific subheaders.

Although this patch introduces L2TPv3 protocol support, there are no
userspace interfaces to create L2TPv3 sessions yet.

Signed-off-by: James Chapman <jchapman@katalix.com>
Reviewed-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

l2tp: Split pppol2tp patch into separate l2tp and ppp parts

This patch splits the pppol2tp driver into separate L2TP and PPP parts
to prepare for L2TPv3 support. In L2TPv3, protocols other than PPP can
be carried, so this split creates a common L2TP core that will handle
the common L2TP bits which protocol support modules such as PPP will
use.

Note that the existing pppol2tp module is split into l2tp_core and
l2tp_ppp by this change.

There are no feature changes here. Internally, however, there are
significant changes, mostly to handle the separation of PPP-specific
data from the L2TP session and to provide hooks in the core for
modules like PPP to access.

Signed-off-by: James Chapman <jchapman@katalix.com>
Reviewed-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>