clean up names related to socket filtering and bpf in the following way:
- everything that deals with sockets keeps 'sk_*' prefix
- everything that is pure BPF is changed to 'bpf_*' prefix

split 'struct sk_filter' into
struct sk_filter {
	atomic_t        refcnt;
	struct rcu_head rcu;
	struct bpf_prog *prog;
};
and
struct bpf_prog {
        u32                     jited:1,
                                len:31;
        struct sock_fprog_kern  *orig_prog;
        unsigned int            (*bpf_func)(const struct sk_buff *skb,
                                            const struct bpf_insn *filter);
        union {
                struct sock_filter      insns[0];
                struct bpf_insn         insnsi[0];
                struct work_struct      work;
        };
};
so that 'struct bpf_prog' can be used independent of sockets and cleans up
'unattached' bpf use cases

split SK_RUN_FILTER macro into:
    SK_RUN_FILTER to be used with 'struct sk_filter *' and
    BPF_PROG_RUN to be used with 'struct bpf_prog *'

__sk_filter_release(struct sk_filter *) gains
__bpf_prog_release(struct bpf_prog *) helper function

also perform related renames for the functions that work
with 'struct bpf_prog *', since they're on the same lines:

sk_filter_size -> bpf_prog_size
sk_filter_select_runtime -> bpf_prog_select_runtime
sk_filter_free -> bpf_prog_free
sk_unattached_filter_create -> bpf_prog_create
sk_unattached_filter_destroy -> bpf_prog_destroy
sk_store_orig_filter -> bpf_prog_store_orig_filter
sk_release_orig_filter -> bpf_release_orig_filter
__sk_migrate_filter -> bpf_migrate_filter
__sk_prepare_filter -> bpf_prepare_filter

API for attaching classic BPF to a socket stays the same:
sk_attach_filter(prog, struct sock *)/sk_detach_filter(struct sock *)
and SK_RUN_FILTER(struct sk_filter *, ctx) to execute a program
which is used by sockets, tun, af_packet

API for 'unattached' BPF programs becomes:
bpf_prog_create(struct bpf_prog **)/bpf_prog_destroy(struct bpf_prog *)
and BPF_PROG_RUN(struct bpf_prog *, ctx) to execute a program
which is used by isdn, ppp, team, seccomp, ptp, xt_bpf, cls_bpf, test_bpf

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Conflicts:
	drivers/infiniband/hw/cxgb4/device.c

The cxgb4 conflict was simply overlapping changes.

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

Commit 568f194e8bd16c353ad50f9ab95d98b20578a39d ("net: ppp: use
sk_unattached_filter api") inadvertently changed the logic when setting
PPP pass and active filters. This applies to both the generic PPP subsystem
implemented by drivers/net/ppp/ppp_generic.c and the ISDN PPP subsystem
implemented by drivers/isdn/i4l/isdn_ppp.c. The original code in ppp_ioctl()
(or isdn_ppp_ioctl(), resp.) handling PPPIOCSPASS and PPPIOCSACTIVE allowed to
remove a pass/active filter previously set by using a filter of length zero.
However, with the new code this is not possible anymore as this case is not
explicitly checked for, which leads to passing NULL as a filter to
sk_unattached_filter_create(). This results in returning EINVAL to the caller.

Additionally, the variables ppp->pass_filter and ppp->active_filter (or
is->pass_filter and is->active_filter, resp.) are not reset to NULL, although
the filters they point to may have been destroyed by
sk_unattached_filter_destroy(), so in this EINVAL case dangling pointers are
left behind (provided the pointers were previously non-NULL).

This patch corrects both problems by checking whether the filter passed is
empty or non-empty, and prevents sk_unattached_filter_create() from being
called in the first case. Moreover, the pointers are always reset to NULL
as soon as sk_unattached_filter_destroy() returns.

Signed-off-by: Christoph Schulz <develop@kristov.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Commit d762d038497c9df51c19fcbe69b094b3bf8e5568 resets the counter holding the
next sequence number for multilink PPP fragments to zero whenever the
SC_MULTILINK flag is set. However, this counter only exists if
CONFIG_PPP_MULTILINK is defined. Consequently, the new code has to be enclosed
within #ifdef CONFIG_PPP_MULTILINK ... #endif.

Signed-off-by: Christoph Schulz <develop@kristov.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

If using a demand-dialled PPP unit for a PPP multilink master, the pppd
daemon needs to reset the sequence counter between two connections. This
allows the daemon to reuse the PPP unit instead of destroying and recreating
it. As there is no API to reset the counter, this patch resets the counter
whenever the SC_MULTILINK flag is set.

Signed-off-by: Christoph Schulz <develop@kristov.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Extend alloc_netdev{,_mq{,s}}() to take name_assign_type as argument, and convert
all users to pass NET_NAME_UNKNOWN.

Coccinelle patch:

@@
expression sizeof_priv, name, setup, txqs, rxqs, count;
@@

(
-alloc_netdev_mqs(sizeof_priv, name, setup, txqs, rxqs)
+alloc_netdev_mqs(sizeof_priv, name, NET_NAME_UNKNOWN, setup, txqs, rxqs)
|
-alloc_netdev_mq(sizeof_priv, name, setup, count)
+alloc_netdev_mq(sizeof_priv, name, NET_NAME_UNKNOWN, setup, count)
|
-alloc_netdev(sizeof_priv, name, setup)
+alloc_netdev(sizeof_priv, name, NET_NAME_UNKNOWN, setup)
)

v9: move comments here from the wrong commit

Signed-off-by: Tom Gundersen <teg@jklm.no>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Commit 568f194e8bd16c353ad50f9ab95d98b20578a39d ("net: ppp: use
sk_unattached_filter api") causes sk_chk_filter() to be called twice when
setting a PPP pass or active filter. This applies to both the generic PPP
subsystem implemented by drivers/net/ppp/ppp_generic.c and the ISDN PPP
subsystem implemented by drivers/isdn/i4l/isdn_ppp.c. The first call is from
within get_filter(). The second one is through the call chain

  ppp_ioctl() or isdn_ppp_ioctl()
  --> sk_unattached_filter_create()
      --> __sk_prepare_filter()
          --> sk_chk_filter()

The first call from within get_filter() should be deleted as get_filter() is
called just before calling sk_unattached_filter_create() later on, which
eventually calls sk_chk_filter() anyway.

For 3.15.x, this proposed change is a bugfix rather than a pure optimization as
in that branch, sk_chk_filter() may replace filter codes by other codes which
are not recognized when executing sk_chk_filter() a second time. So with
3.15.x, if sk_chk_filter() is called twice, the second invocation may yield
EINVAL (this depends on the filter codes found in the filter to be set, but
because the replacement is done for frequently used codes, this is almost
always the case). The net effect is that setting pass and/or active PPP filters
does not work anymore, since sk_unattached_filter_create() always returns
EINVAL due to the second call to sk_chk_filter(), regardless whether the filter
was originally sane or not.

Signed-off-by: Christoph Schulz <develop@kristov.de>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The PPP channel MTU is used with Multilink PPP when ppp_mp_explode() (see
ppp_generic module) tries to determine how big a fragment might be. According
to RFC 1661, the MTU excludes the 2-byte PPP protocol field, see the
corresponding comment and code in ppp_mp_explode():

		/*
		 * hdrlen includes the 2-byte PPP protocol field, but the
		 * MTU counts only the payload excluding the protocol field.
		 * (RFC1661 Section 2)
		 */
		mtu = pch->chan->mtu - (hdrlen - 2);

However, the pppoe module *does* include the PPP protocol field in the channel
MTU, which is wrong as it causes the PPP payload to be 1-2 bytes too big under
certain circumstances (one byte if PPP protocol compression is used, two
otherwise), causing the generated Ethernet packets to be dropped. So the pppoe
module has to subtract two bytes from the channel MTU. This error only
manifests itself when using Multilink PPP, as otherwise the channel MTU is not
used anywhere.

In the following, I will describe how to reproduce this bug. We configure two
pppd instances for multilink PPP over two PPPoE links, say eth2 and eth3, with
a MTU of 1492 bytes for each link and a MRRU of 2976 bytes. (This MRRU is
computed by adding the two link MTUs and subtracting the MP header twice, which
is 4 bytes long.) The necessary pppd statements on both sides are "multilink
mtu 1492 mru 1492 mrru 2976". On the client side, we additionally need "plugin
rp-pppoe.so eth2" and "plugin rp-pppoe.so eth3", respectively; on the server
side, we additionally need to start two pppoe-server instances to be able to
establish two PPPoE sessions, one over eth2 and one over eth3. We set the MTU
of the PPP network interface to the MRRU (2976) on both sides of the connection
in order to make use of the higher bandwidth. (If we didn't do that, IP
fragmentation would kick in, which we want to avoid.)

Now we send a ICMPv4 echo request with a payload of 2948 bytes from client to
server over the PPP link. This results in the following network packet:

   2948 (echo payload)
 +    8 (ICMPv4 header)
 +   20 (IPv4 header)
---------------------
   2976 (PPP payload)

These 2976 bytes do not exceed the MTU of the PPP network interface, so the
IP packet is not fragmented. Now the multilink PPP code in ppp_mp_explode()
prepends one protocol byte (0x21 for IPv4), making the packet one byte bigger
than the negotiated MRRU. So this packet would have to be divided in three
fragments. But this does not happen as each link MTU is assumed to be two bytes
larger. So this packet is diveded into two fragments only, one of size 1489 and
one of size 1488. Now we have for that bigger fragment:

   1489 (PPP payload)
 +    4 (MP header)
 +    2 (PPP protocol field for the MP payload (0x3d))
 +    6 (PPPoE header)
--------------------------
   1501 (Ethernet payload)

This packet exceeds the link MTU and is discarded.

If one configures the link MTU on the client side to 1501, one can see the
discarded Ethernet frames with tcpdump running on the client. A

ping -s 2948 -c 1 192.168.15.254

leads to the smaller fragment that is correctly received on the server side:

(tcpdump -vvvne -i eth3 pppoes and ppp proto 0x3d)
52:54:00:ad:87:fd > 52:54:00:79:5c:d0, ethertype PPPoE S (0x8864),
  length 1514: PPPoE  [ses 0x3] MLPPP (0x003d), length 1494: seq 0x000,
  Flags [end], length 1492

and to the bigger fragment that is not received on the server side:

(tcpdump -vvvne -i eth2 pppoes and ppp proto 0x3d)
52:54:00:70:9e:89 > 52:54:00:5d:6f:b0, ethertype PPPoE S (0x8864),
  length 1515: PPPoE  [ses 0x5] MLPPP (0x003d), length 1495: seq 0x000,
  Flags [begin], length 1493

With the patch below, we correctly obtain three fragments:

52:54:00:ad:87:fd > 52:54:00:79:5c:d0, ethertype PPPoE S (0x8864),
  length 1514: PPPoE  [ses 0x1] MLPPP (0x003d), length 1494: seq 0x000,
  Flags [begin], length 1492
52:54:00:70:9e:89 > 52:54:00:5d:6f:b0, ethertype PPPoE S (0x8864),
  length 1514: PPPoE  [ses 0x1] MLPPP (0x003d), length 1494: seq 0x000,
  Flags [none], length 1492
52:54:00:ad:87:fd > 52:54:00:79:5c:d0, ethertype PPPoE S (0x8864),
  length 27: PPPoE  [ses 0x1] MLPPP (0x003d), length 7: seq 0x000,
  Flags [end], length 5

And the ICMPv4 echo request is successfully received at the server side:

IP (tos 0x0, ttl 64, id 21925, offset 0, flags [DF], proto ICMP (1),
  length 2976)
    192.168.222.2 > 192.168.15.254: ICMP echo request, id 30530, seq 0,
      length 2956

The bug was introduced in commit c9aa6895371b2a257401f59d3393c9f7ac5a8698
("[PPPOE]: Advertise PPPoE MTU") from the very beginning. This patch applies
to 3.10 upwards but the fix can be applied (with minor modifications) to
kernels as old as 2.6.32.

Signed-off-by: Christoph Schulz <develop@kristov.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Ideally, we would need to generate IP ID using a per destination IP
generator.

linux kernels used inet_peer cache for this purpose, but this had a huge
cost on servers disabling MTU discovery.

1) each inet_peer struct consumes 192 bytes

2) inetpeer cache uses a binary tree of inet_peer structs,
   with a nominal size of ~66000 elements under load.

3) lookups in this tree are hitting a lot of cache lines, as tree depth
   is about 20.

4) If server deals with many tcp flows, we have a high probability of
   not finding the inet_peer, allocating a fresh one, inserting it in
   the tree with same initial ip_id_count, (cf secure_ip_id())

5) We garbage collect inet_peer aggressively.

IP ID generation do not have to be 'perfect'

Goal is trying to avoid duplicates in a short period of time,
so that reassembly units have a chance to complete reassembly of
fragments belonging to one message before receiving other fragments
with a recycled ID.

We simply use an array of generators, and a Jenkin hash using the dst IP
as a key.

ipv6_select_ident() is put back into net/ipv6/ip6_output.c where it
belongs (it is only used from this file)

secure_ip_id() and secure_ipv6_id() no longer are needed.

Rename ip_select_ident_more() to ip_select_ident_segs() to avoid
unnecessary decrement/increment of the number of segments.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>