net: ipv6: ping: Use socket mark in routing lookup

[net-next commit bf439b3154ce49d81a79b14f9fab18af99018ae2]

Change-Id: I8356e9132088c75d4510021c6e4c2641d772087a
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: ipv6: autoconf routes into per-device tables

Currently, IPv6 router discovery always puts routes into
RT6_TABLE_MAIN. This causes problems for connection managers
that want to support multiple simultaneous network connections
and want control over which one is used by default (e.g., wifi
and wired).

To work around this connection managers typically take the routes
they prefer and copy them to static routes with low metrics in
the main table. This puts the burden on the connection manager
to watch netlink to see if the routes have changed, delete the
routes when their lifetime expires, etc.

Instead, this patch adds a per-interface sysctl to have the
kernel put autoconf routes into different tables. This allows
each interface to have its own autoconf table, and choosing the
default interface (or using different interfaces at the same
time for different types of traffic) can be done using
appropriate ip rules.

The sysctl behaves as follows:

- = 0: default. Put routes into RT6_TABLE_MAIN as before.
- > 0: manual. Put routes into the specified table.
- < 0: automatic. Add the absolute value of the sysctl to the
       device's ifindex, and use that table.

The automatic mode is most useful in conjunction with
net.ipv6.conf.default.accept_ra_rt_table. A connection manager
or distribution could set it to, say, -100 on boot, and
thereafter just use IP rules.

Change-Id: I093d39fb06ec413905dc0d0d5792c1bc5d5c73a9
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
net: add a sysctl to reflect the fwmark on replies

Kernel-originated IP packets that have no user socket associated
with them (e.g., ICMP errors and echo replies, TCP RSTs, etc.)
are emitted with a mark of zero. Add a sysctl to make them have
the same mark as the packet they are replying to.

This allows an administrator that wishes to do so to use
mark-based routing, firewalling, etc. for these replies by
marking the original packets inbound.

Tested using user-mode linux:
 - ICMP/ICMPv6 echo replies and errors.
 - TCP RST packets (IPv4 and IPv6).

Change-Id: I95d896647b278d092ef331d1377b959da1deb042
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
net: support marking accepting TCP sockets

When using mark-based routing, sockets returned from accept()
may need to be marked differently depending on the incoming
connection request.

This is the case, for example, if different socket marks identify
different networks: a listening socket may want to accept
connections from all networks, but each connection should be
marked with the network that the request came in on, so that
subsequent packets are sent on the correct network.

This patch adds a sysctl to mark TCP sockets based on the fwmark
of the incoming SYN packet. If enabled, and an unmarked socket
receives a SYN, then the SYN packet's fwmark is written to the
connection's inet_request_sock, and later written back to the
accepted socket when the connection is established.  If the
socket already has a nonzero mark, then the behaviour is the same
as it is today, i.e., the listening socket's fwmark is used.

Black-box tested using user-mode linux:

- IPv4/IPv6 SYN+ACK, FIN, etc. packets are routed based on the
  mark of the incoming SYN packet.
- The socket returned by accept() is marked with the mark of the
  incoming SYN packet.
- Tested with syncookies=1 and syncookies=2.

Change-Id: I5e8c9b989762a93f3eb5a0c1b4df44f62d57f3cb
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
n_tty: Fix n_tty_write crash when echoing in raw mode

The tty atomic_write_lock does not provide an exclusion guarantee for
the tty driver if the termios settings are LECHO & !OPOST.  And since
it is unexpected and not allowed to call TTY buffer helpers like
tty_insert_flip_string concurrently, this may lead to crashes when
concurrect writers call pty_write. In that case the following two
writers:
* the ECHOing from a workqueue and
* pty_write from the process
race and can overflow the corresponding TTY buffer like follows.

If we look into tty_insert_flip_string_fixed_flag, there is:
  int space = __tty_buffer_request_room(port, goal, flags);
  struct tty_buffer *tb = port->buf.tail;
  ...
  memcpy(char_buf_ptr(tb, tb->used), chars, space);
  ...
  tb->used += space;

so the race of the two can result in something like this:
              A                                B
__tty_buffer_request_room
                                  __tty_buffer_request_room
memcpy(buf(tb->used), ...)
tb->used += space;
                                  memcpy(buf(tb->used), ...) ->BOOM

B's memcpy is past the tty_buffer due to the previous A's tb->used
increment.

Since the N_TTY line discipline input processing can output
concurrently with a tty write, obtain the N_TTY ldisc output_lock to
serialize echo output with normal tty writes.  This ensures the tty
buffer helper tty_insert_flip_string is not called concurrently and
everything is fine.

Note that this is nicely reproducible by an ordinary user using
forkpty and some setup around that (raw termios + ECHO). And it is
present in kernels at least after commit
d945cb9cce20ac7143c2de8d88b187f62db99bdc (pty: Rework the pty layer to
use the normal buffering logic) in 2.6.31-rc3.

js: add more info to the commit log
js: switch to bool
js: lock unconditionally
js: lock only the tty->ops->write call

Change-Id: I63e622f7303d46a784116b26f5937ae65036b23b
References: CVE-2014-0196
Reported-and-tested-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Cherry-picked from git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
branch: master
commit: 4291086b1f081b869c6d79e5b7441633dc3ace00
Needed some tweaks because there is no
  bddc715 2012-10-18 jslaby@suse.cz TTY: move ldisc data from tty_struct: locks

Signed-off-by: JP Abgrall <jpa@google.com>
net: Fix "ip rule delete table 256"

[ Upstream commit 13eb2ab2d33c57ebddc57437a7d341995fc9138c ]

When trying to delete a table >= 256 using iproute2 the local table
will be deleted.
The table id is specified as a netlink attribute when it needs more then
8 bits and iproute2 then sets the table field to RT_TABLE_UNSPEC (0).
Preconditions to matching the table id in the rule delete code
doesn't seem to take the "table id in netlink attribute" into condition
so the frh_get_table helper function never gets to do its job when
matching against current rule.
Use the helper function twice instead of peaking at the table value directly.

Originally reported at: http://bugs.debian.org/724783

Reported-by: Nicolas HICHER <nhicher@avencall.com>
Signed-off-by: Andreas Henriksson <andreas@fatal.se>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>