The skbs processed by ip_cmsg_recv() are not guaranteed to
be linear e.g. when sending UDP packets over loopback with
MSGMORE.
Using csum_partial() on [potentially] the whole skb len
is dangerous; instead be on the safe side and use skb_checksum().

Thanks to syzkaller team to detect the issue and provide the
reproducer.

v1 -> v2:
 - move the variable declaration in a tighter scope

Fixes: ad6f939a ("ip: Add offset parameter to ip_cmsg_recv")
Reported-by: NAndrey Konovalov <andreyknvl@google.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Andrey Konovalov got crashes in __ip_options_echo() when a NULL skb->dst
is accessed.

ipv4_pktinfo_prepare() should not drop the dst if (evil) IP options
are present.

We could refine the test to the presence of ts_needtime or srr,
but IP options are not often used, so let's be conservative.

Thanks to syzkaller team for finding this bug.

Fixes: d826eb14 ("ipv4: PKTINFO doesnt need dst reference")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: NAndrey Konovalov <andreyknvl@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

sizeof(struct cmsghdr) and sizeof(struct compat_cmsghdr) already aligned.
remove use CMSG_ALIGN(sizeof(struct cmsghdr)) and
CMSG_COMPAT_ALIGN(sizeof(struct compat_cmsghdr)) keep code consistent.
Signed-off-by: Nyuan linyu <Linyu.Yuan@alcatel-sbell.com.cn>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

IP_MULTICAST_IF fails if sk_bound_dev_if is already set and the new index
does not match it. e.g.,

    ntpd[15381]: setsockopt IP_MULTICAST_IF 192.168.1.23 fails: Invalid argument

Relax the check in setsockopt to allow setting mc_index to an L3 slave if
sk_bound_dev_if points to an L3 master.

Make a similar change for IPv6. In this case change the device lookup to
take the rcu_read_lock avoiding a refcnt. The rcu lock is also needed for
the lookup of a potential L3 master device.

This really only silences a setsockopt failure since uses of mc_index are
secondary to sk_bound_dev_if if it is set. In both cases, if either index
is an L3 slave or master, lookups are directed to the same FIB table so
relaxing the check at setsockopt time causes no harm.

Patch is based on a suggested change by Darwin for a problem noted in
their code base.
Suggested-by: NDarwin Dingel <darwin.dingel@alliedtelesis.co.nz>
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When we send a packet for our own local address on a non-loopback
interface (e.g. eth0), due to the change had been introduced from
commit 0b922b7a ("net: original ingress device index in PKTINFO"), the
original ingress device index would be set as the loopback interface.
However, the packet should be considered as if it is being arrived via the
sending interface (eth0), otherwise it would break the expectation of the
userspace application (e.g. the DHCPRELEASE message from dhcp_release
binary would be ignored by the dnsmasq daemon, since it come from lo which
is not the interface dnsmasq bind to)

Fixes: 0b922b7a ("net: original ingress device index in PKTINFO")
Acked-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NWei Zhang <asuka.com@163.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This was entirely automated, using the script by Al:

  PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
  sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
        $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)

to do the replacement at the end of the merge window.
Requested-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Socket cmsg IP(V6)_RECVORIGDSTADDR checks that port range lies within
the packet. For sockets that have transport headers pulled, transport
offset can be negative. Use signed comparison to avoid overflow.

Fixes: e6afc8ac ("udp: remove headers from UDP packets before queueing")
Reported-by: NNisar Jagabar <njagabar@cloudmark.com>
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

So that we can use it even after orphaining the skbuff.
Suggested-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The IP stack records the largest fragment of a reassembled packet
in IPCB(skb)->frag_max_size. When reading a datagram or raw packet
that arrived fragmented, expose the value to allow applications to
estimate receive path MTU.

Tested:
  Sent data over a veth pair of which the source has a small mtu.
  Sent data using netcat, received using a dedicated process.

  Verified that the cmsg IP_RECVFRAGSIZE is returned only when
  data arrives fragmented, and in that cases matches the veth mtu.

    ip link add veth0 type veth peer name veth1

    ip netns add from
    ip netns add to

    ip link set dev veth1 netns to
    ip netns exec to ip addr add dev veth1 192.168.10.1/24
    ip netns exec to ip link set dev veth1 up

    ip link set dev veth0 netns from
    ip netns exec from ip addr add dev veth0 192.168.10.2/24
    ip netns exec from ip link set dev veth0 up
    ip netns exec from ip link set dev veth0 mtu 1300
    ip netns exec from ethtool -K veth0 ufo off

    dd if=/dev/zero bs=1 count=1400 2>/dev/null > payload

    ip netns exec to ./recv_cmsg_recvfragsize -4 -u -p 6000 &
    ip netns exec from nc -q 1 -u 192.168.10.1 6000 < payload

  using github.com/wdebruij/kerneltools/blob/master/tests/recvfragsize.c
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

First bug was added in commit ad6f939a ("ip: Add offset parameter to
ip_cmsg_recv") : Tom missed that ipv4 udp messages could be received on
AF_INET6 socket. ip_cmsg_recv(msg, skb) should have been replaced by
ip_cmsg_recv_offset(msg, skb, sizeof(struct udphdr));

Then commit e6afc8ac ("udp: remove headers from UDP packets before
queueing") forgot to adjust the offsets now UDP headers are pulled
before skb are put in receive queue.

Fixes: ad6f939a ("ip: Add offset parameter to ip_cmsg_recv")
Fixes: e6afc8ac ("udp: remove headers from UDP packets before queueing")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Sam Kumar <samanthakumar@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Tested-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In commit f02db315 ("ipv4: IP_TOS and IP_TTL can be specified as
ancillary data") Francesco added IP_TOS values specified as integer.

However, kernel sends to userspace (at recvmsg() time) an IP_TOS value
in a single byte, when IP_RECVTOS is set on the socket.

It can be very useful to reflect all ancillary options as given by the
kernel in a subsequent sendmsg(), instead of aborting the sendmsg() with
EINVAL after Francesco patch.

So this patch extends IP_TOS ancillary to accept an u8, so that an UDP
server can simply reuse same ancillary block without having to mangle
it.

Jesper can then augment
https://github.com/netoptimizer/network-testing/blob/master/src/udp_example02.c
to add TOS reflection ;)

Fixes: f02db315 ("ipv4: IP_TOS and IP_TTL can be specified as ancillary data")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Francesco Fusco <ffusco@redhat.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

__sock_cmsg_send() might return different error codes, not only -EINVAL.

Fixes: 24025c46 ("ipv4: process socket-level control messages in IPv4")
Fixes: ad1e46a8 ("ipv6: process socket-level control messages in IPv6")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: NSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Applications such as OSPF and BFD need the original ingress device not
the VRF device; the latter can be derived from the former. To that end
add the skb_iif to inet_skb_parm and set it in ipv4 code after clearing
the skb control buffer similar to IPv6. From there the pktinfo can just
pull it from cb with the PKTINFO_SKB_CB cast.

The previous patch moving the skb->dev change to L3 means nothing else
is needed for IPv6; it just works.
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We should call consume_skb(skb) when skb is properly consumed,
or kfree_skb(skb) when skb must be dropped in error case.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

On udp sockets, recv cmsg IP_CMSG_CHECKSUM returns a checksum over
the packet payload. Since commit e6afc8ac pulled the headers,
taking skb->data as the start of transport header is incorrect. Use
the transport header pointer.

Also, when peeking at an offset from the start of the packet, only
return a checksum from the start of the peeked data. Note that the
cmsg does not subtract a tail checkum when reading truncated data.

Fixes: e6afc8ac ("udp: remove headers from UDP packets before queueing")
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The socket is either locked if we hold the slock spin_lock for
lock_sock_fast and unlock_sock_fast or we own the lock (sk_lock.owned
!= 0). Check for this and at the same time improve that the current
thread/cpu is really holding the lock.
Signed-off-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Process socket-level control messages by invoking
__sock_cmsg_send in ip_cmsg_send for control messages on
the SOL_SOCKET layer.

This makes sure whenever ip_cmsg_send is called in udp, icmp,
and raw, we also process socket-level control messages.

Note that this commit interprets new control messages that
were ignored before. As such, this commit does not change
the behavior of IPv4 control messages.
Signed-off-by: NSoheil Hassas Yeganeh <soheil@google.com>
Acked-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NNikolay Borisov <kernel@kyup.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Dmitry reported memory leaks of IP options allocated in
ip_cmsg_send() when/if this function returns an error.

Callers are responsible for the freeing.

Many thanks to Dmitry for the report and diagnostic.
Reported-by: NDmitry Vyukov <dvyukov@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NNikolay Borisov <kernel@kyup.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Sasha reported the following lockdep warning:

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(sk_lock-AF_INET);
                                lock(rtnl_mutex);
                                lock(sk_lock-AF_INET);
   lock(rtnl_mutex);

This is due to that for IP_MSFILTER and MCAST_MSFILTER, we take
rtnl lock before the socket lock in setsockopt() path, but take
the socket lock before rtnl lock in getsockopt() path. All the
rest optnames are setsockopt()-only.

Fix this by aligning the getsockopt() path with the setsockopt()
path, so that all mcast socket path would be locked in the same
order.

Note, IPv6 part is different where rtnl lock is not held.

Fixes: 54ff9ef3 ("ipv4, ipv6: kill ip_mc_{join, leave}_group and ipv6_sock_mc_{join, drop}")
Reported-by: NSasha Levin <sasha.levin@oracle.com>
Cc: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: NMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

ICMP messages can trigger ICMP and local errors. In this case
serr->port is 0 and starting from Linux 4.0 we do not return
the original target address to the error queue readers.
Add function to define which errors provide addr_offset.
With this fix my ping command is not silent anymore.

Fixes: c247f053 ("ip: fix error queue empty skb handling")
Signed-off-by: NJulian Anastasov <ja@ssi.bg>
Acked-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When an application needs to force a source IP on an active TCP socket
it has to use bind(IP, port=x).

As most applications do not want to deal with already used ports, x is
often set to 0, meaning the kernel is in charge to find an available
port.
But kernel does not know yet if this socket is going to be a listener or
be connected.
It has very limited choices (no full knowledge of final 4-tuple for a
connect())

With limited ephemeral port range (about 32K ports), it is very easy to
fill the space.

This patch adds a new SOL_IP socket option, asking kernel to ignore
the 0 port provided by application in bind(IP, port=0) and only
remember the given IP address.

The port will be automatically chosen at connect() time, in a way
that allows sharing a source port as long as the 4-tuples are unique.

This new feature is available for both IPv4 and IPv6 (Thanks Neal)

Tested:

Wrote a test program and checked its behavior on IPv4 and IPv6.

strace(1) shows sequences of bind(IP=127.0.0.2, port=0) followed by
connect().
Also getsockname() show that the port is still 0 right after bind()
but properly allocated after connect().

socket(PF_INET, SOCK_STREAM, IPPROTO_IP) = 5
setsockopt(5, SOL_IP, IP_BIND_ADDRESS_NO_PORT, [1], 4) = 0
bind(5, {sa_family=AF_INET, sin_port=htons(0), sin_addr=inet_addr("127.0.0.2")}, 16) = 0
getsockname(5, {sa_family=AF_INET, sin_port=htons(0), sin_addr=inet_addr("127.0.0.2")}, [16]) = 0
connect(5, {sa_family=AF_INET, sin_port=htons(53174), sin_addr=inet_addr("127.0.0.3")}, 16) = 0
getsockname(5, {sa_family=AF_INET, sin_port=htons(38050), sin_addr=inet_addr("127.0.0.2")}, [16]) = 0

IPv6 test :

socket(PF_INET6, SOCK_STREAM, IPPROTO_IP) = 7
setsockopt(7, SOL_IP, IP_BIND_ADDRESS_NO_PORT, [1], 4) = 0
bind(7, {sa_family=AF_INET6, sin6_port=htons(0), inet_pton(AF_INET6, "::1", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = 0
getsockname(7, {sa_family=AF_INET6, sin6_port=htons(0), inet_pton(AF_INET6, "::1", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, [28]) = 0
connect(7, {sa_family=AF_INET6, sin6_port=htons(57300), inet_pton(AF_INET6, "::1", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = 0
getsockname(7, {sa_family=AF_INET6, sin6_port=htons(60964), inet_pton(AF_INET6, "::1", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, [28]) = 0

I was able to bind()/connect() a million concurrent IPv4 sockets,
instead of ~32000 before patch.

lpaa23:~# ulimit -n 1000010
lpaa23:~# ./bind --connect --num-flows=1000000 &
1000000 sockets

lpaa23:~# grep TCP /proc/net/sockstat
TCP: inuse 2000063 orphan 0 tw 47 alloc 2000157 mem 66

Check that a given source port is indeed used by many different
connections :

lpaa23:~# ss -t src :40000 | head -10
State      Recv-Q Send-Q   Local Address:Port          Peer Address:Port
ESTAB      0      0           127.0.0.2:40000         127.0.202.33:44983
ESTAB      0      0           127.0.0.2:40000         127.2.27.240:44983
ESTAB      0      0           127.0.0.2:40000           127.2.98.5:44983
ESTAB      0      0           127.0.0.2:40000        127.0.124.196:44983
ESTAB      0      0           127.0.0.2:40000         127.2.139.38:44983
ESTAB      0      0           127.0.0.2:40000          127.1.59.80:44983
ESTAB      0      0           127.0.0.2:40000          127.3.6.228:44983
ESTAB      0      0           127.0.0.2:40000          127.0.38.53:44983
ESTAB      0      0           127.0.0.2:40000         127.1.197.10:44983
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The ipv4 code uses a mixture of coding styles. In some instances check
for non-NULL pointer is done as x != NULL and sometimes as x. x is
preferred according to checkpatch and this patch makes the code
consistent by adopting the latter form.

No changes detected by objdiff.
Signed-off-by: NIan Morris <ipm@chirality.org.uk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The ipv4 code uses a mixture of coding styles. In some instances check
for NULL pointer is done as x == NULL and sometimes as !x. !x is
preferred according to checkpatch and this patch makes the code
consistent by adopting the latter form.

No changes detected by objdiff.
Signed-off-by: NIan Morris <ipm@chirality.org.uk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

in favor of their inner __ ones, which doesn't grab rtnl.

As these functions need to operate on a locked socket, we can't be
grabbing rtnl by then. It's too late and doing so causes reversed
locking.

So this patch:
- move rtnl handling to callers instead while already fixing some
  reversed locking situations, like on vxlan and ipvs code.
- renames __ ones to not have the __ mark:
  __ip_mc_{join,leave}_group -> ip_mc_{join,leave}_group
  __ipv6_sock_mc_{join,drop} -> ipv6_sock_mc_{join,drop}
Signed-off-by: NMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There are some setsockopt operations in ipv4 and ipv6 that are grabbing
rtnl after having grabbed the socket lock. Yet this makes it impossible
to do operations that have to lock the socket when already within a rtnl
protected scope, like ndo dev_open and dev_stop.

We normally take coarse grained locks first but setsockopt inverted that.

So this patch invert the lock logic for these operations and makes
setsockopt grab rtnl if it will be needed prior to grabbing socket lock.
Signed-off-by: NMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When reading from the error queue, msg_name and msg_control are only
populated for some errors. A new exception for empty timestamp skbs
added a false positive on icmp errors without payload.

`traceroute -M udpconn` only displayed gateways that return payload
with the icmp error: the embedded network headers are pulled before
sock_queue_err_skb, leaving an skb with skb->len == 0 otherwise.

Fix this regression by refining when msg_name and msg_control
branches are taken. The solutions for the two fields are independent.

msg_name only makes sense for errors that configure serr->port and
serr->addr_offset. Test the first instead of skb->len. This also fixes
another issue. saddr could hold the wrong data, as serr->addr_offset
is not initialized  in some code paths, pointing to the start of the
network header. It is only valid when serr->port is set (non-zero).

msg_control support differs between IPv4 and IPv6. IPv4 only honors
requests for ICMP and timestamps with SOF_TIMESTAMPING_OPT_CMSG. The
skb->len test can simply be removed, because skb->dev is also tested
and never true for empty skbs. IPv6 honors requests for all errors
aside from local errors and timestamps on empty skbs.

In both cases, make the policy more explicit by moving this logic to
a new function that decides whether to process msg_control and that
optionally prepares the necessary fields in skb->cb[]. After this
change, the IPv4 and IPv6 paths are more similar.

The last case is rxrpc. Here, simply refine to only match timestamps.

Fixes: 49ca0d8b ("net-timestamp: no-payload option")
Reported-by: NJan Niehusmann <jan@gondor.com>
Signed-off-by: NWillem de Bruijn <willemb@google.com>

----

Changes
  v1->v2
  - fix local origin test inversion in ip6_datagram_support_cmsg
  - make v4 and v6 code paths more similar by introducing analogous
    ipv4_datagram_support_cmsg
  - fix compile bug in rxrpc
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add timestamping option SOF_TIMESTAMPING_OPT_TSONLY. For transmit
timestamps, this loops timestamps on top of empty packets.

Doing so reduces the pressure on SO_RCVBUF. Payload inspection and
cmsg reception (aside from timestamps) are no longer possible. This
works together with a follow on patch that allows administrators to
only allow tx timestamping if it does not loop payload or metadata.
Signed-off-by: NWillem de Bruijn <willemb@google.com>

----

Changes (rfc -> v1)
  - add documentation
  - remove unnecessary skb->len test (thanks to Richard Cochran)
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The sockaddr is returned in IP(V6)_RECVERR as part of errhdr. That
structure is defined and allocated on the stack as

    struct {
            struct sock_extended_err ee;
            struct sockaddr_in(6)    offender;
    } errhdr;

The second part is only initialized for certain SO_EE_ORIGIN values.
Always initialize it completely.

An MTU exceeded error on a SOCK_RAW/IPPROTO_RAW is one example that
would return uninitialized bytes.
Signed-off-by: NWillem de Bruijn <willemb@google.com>

----

Also verified that there is no padding between errhdr.ee and
errhdr.offender that could leak additional kernel data.
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add ip_cmsg_recv_offset function which takes an offset argument
that indicates the starting offset in skb where data is being received
from. This will be useful in the case of UDP and provided checksum
to user space.

ip_cmsg_recv is an inline call to ip_cmsg_recv_offset with offset of
zero.
Signed-off-by: NTom Herbert <therbert@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add ip_cmsg_recv_offset function which takes an offset argument
that indicates the starting offset in skb where data is being received
from. This will be useful in the case of UDP and provided checksum
to user space.

ip_cmsg_recv is an inline call to ip_cmsg_recv_offset with offset of
zero.
Signed-off-by: NTom Herbert <therbert@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Move the IP_CMSG_* constants from ip_sockglue.c to inet_sock.h so that
they can be referenced in other source files.

Restructure ip_cmsg_recv to not go through flags using shift, check
for flags by 'and'. This eliminates both the shift and a conditional
per flag check.
Signed-off-by: NTom Herbert <therbert@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Introduce helper macro for_each_cmsghdr as a wrapper of the enumerating
cmsghdr from msghdr, just cleanup.
Signed-off-by: NGu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Allow reading of timestamps and cmsg at the same time on all relevant
socket families. One use is to correlate timestamps with egress
device, by asking for cmsg IP_PKTINFO.

on AF_INET sockets, call the relevant function (ip_cmsg_recv). To
avoid changing legacy expectations, only do so if the caller sets a
new timestamping flag SOF_TIMESTAMPING_OPT_CMSG.

on AF_INET6 sockets, IPV6_PKTINFO and all other recv cmsg are already
returned for all origins. only change is to set ifindex, which is
not initialized for all error origins.

In both cases, only generate the pktinfo message if an ifindex is
known. This is not the case for ACK timestamps.

The difference between the protocol families is probably a historical
accident as a result of the different conditions for generating cmsg
in the relevant ip(v6)_recv_error function:

ipv4:        if (serr->ee.ee_origin == SO_EE_ORIGIN_ICMP) {
ipv6:        if (serr->ee.ee_origin != SO_EE_ORIGIN_LOCAL) {

At one time, this was the same test bar for the ICMP/ICMP6
distinction. This is no longer true.
Signed-off-by: NWillem de Bruijn <willemb@google.com>

----

Changes
  v1 -> v2
    large rewrite
    - integrate with existing pktinfo cmsg generation code
    - on ipv4: only send with new flag, to maintain legacy behavior
    - on ipv6: send at most a single pktinfo cmsg
    - on ipv6: initialize fields if not yet initialized

The recv cmsg interfaces are also relevant to the discussion of
whether looping packet headers is problematic. For v6, cmsgs that
identify many headers are already returned. This patch expands
that to v4. If it sounds reasonable, I will follow with patches

1. request timestamps without payload with SOF_TIMESTAMPING_OPT_TSONLY
   (http://patchwork.ozlabs.org/patch/366967/)
2. sysctl to conditionally drop all timestamps that have payload or
   cmsg from users without CAP_NET_RAW.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

One line change, in response to catching an occurrence of this bug.
See also fix f4713a3d ("net-timestamp: make tcp_recvmsg call ...")
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use IS_ENABLED(CONFIG_IPV6), to enable this code if IPv6 is
a module.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Fixes: c8e6ad08 ("ipv6: honor IPV6_PKTINFO with v4 mapped addresses on sendmsg")
Acked-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This encapsulates all of the skb_copy_datagram_iovec() callers
with call argument signature "skb, offset, msghdr->msg_iov, length".

When we move to iov_iters in the networking, the iov_iter object will
sit in the msghdr.

Having a helper like this means there will be less places to touch
during that transformation.

Based upon descriptions and patch from Al Viro.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Remove one sparse warning :
net/ipv4/ip_sockglue.c:328:22: warning: incorrect type in assignment (different address spaces)
net/ipv4/ip_sockglue.c:328:22:    expected struct ip_ra_chain [noderef] <asn:4>*next
net/ipv4/ip_sockglue.c:328:22:    got struct ip_ra_chain *[assigned] ra

And replace one rcu_assign_ptr() by RCU_INIT_POINTER() where applicable.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

sk->sk_error_queue is dequeued in four locations. All share the
exact same logic. Deduplicate.

Also collapse the two critical sections for dequeue (at the top of
the recv handler) and signal (at the bottom).

This moves signal generation for the next packet forward, which should
be harmless.

It also changes the behavior if the recv handler exits early with an
error. Previously, a signal for follow-up packets on the errqueue
would then not be scheduled. The new behavior, to always signal, is
arguably a bug fix.

For rxrpc, the change causes the same function to be called repeatedly
for each queued packet (because the recv handler == sk_error_report).
It is likely that all packets will fail for the same reason (e.g.,
memory exhaustion).

This code runs without sk_lock held, so it is not safe to trust that
sk->sk_err is immutable inbetween releasing q->lock and the subsequent
test. Introduce int err just to avoid this potential race.
Signed-off-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>