linux-stable.git/net/ipv4/ip_output.c, branch linux-5.14.y

ipv4: ip_output.c: Fix out-of-bounds warning in ip_copy_addrs()

2021-09-18T11:43:42+00:00

[ Upstream commit 6321c7acb82872ef6576c520b0e178eaad3a25c0 ]

Fix the following out-of-bounds warning:

    In function 'ip_copy_addrs',
        inlined from '__ip_queue_xmit' at net/ipv4/ip_output.c:517:2:
net/ipv4/ip_output.c:449:2: warning: 'memcpy' offset [40, 43] from the object at 'fl' is out of the bounds of referenced subobject 'saddr' with type 'unsigned int' at offset 36 [-Warray-bounds]
      449 |  memcpy(&iph->saddr, &fl4->saddr,
          |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      450 |         sizeof(fl4->saddr) + sizeof(fl4->daddr));
          |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The problem is that the original code is trying to copy data into a
couple of struct members adjacent to each other in a single call to
memcpy(). This causes a legitimate compiler warning because memcpy()
overruns the length of &iph->saddr and &fl4->saddr. As these are just
a couple of struct members, fix this by using direct assignments,
instead of memcpy().

This helps with the ongoing efforts to globally enable -Warray-bounds
and get us closer to being able to tighten the FORTIFY_SOURCE routines
on memcpy().

Link: https://github.com/KSPP/linux/issues/109
Reported-by: kernel test robot 
Link: https://lore.kernel.org/lkml/d5ae2e65-1f18-2577-246f-bada7eee6ccd@intel.com/
Signed-off-by: Gustavo A. R. Silva 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

net: ip: avoid OOM kills with large UDP sends over loopback

2021-06-24T18:17:21+00:00

Dave observed number of machines hitting OOM on the UDP send
path. The workload seems to be sending large UDP packets over
loopback. Since loopback has MTU of 64k kernel will try to
allocate an skb with up to 64k of head space. This has a good
chance of failing under memory pressure. What's worse if
the message length is <32k the allocation may trigger an
OOM killer.

This is entirely avoidable, we can use an skb with page frags.

af_unix solves a similar problem by limiting the head
length to SKB_MAX_ALLOC. This seems like a good and simple
approach. It means that UDP messages > 16kB will now
use fragments if underlying device supports SG, if extra
allocator pressure causes regressions in real workloads
we can switch to trying the large allocation first and
falling back.

v4: pre-calculate all the additions to alloclen so
    we can be sure it won't go over order-2

Reported-by: Dave Jones 
Signed-off-by: Jakub Kicinski 
Signed-off-by: David S. Miller

ipv4: ip_output.c: Couple of typo fixes

2021-03-29T00:31:13+00:00

s/readibility/readability/
s/insufficent/insufficient/

Signed-off-by: Bhaskar Chowdhury 
Signed-off-by: David S. Miller

net: use indirect call helpers for dst_output

2021-02-03T22:51:39+00:00

This patch avoids the indirect call for the common case:
ip6_output and ip_output

Signed-off-by: Brian Vazquez 
Signed-off-by: Jakub Kicinski

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2021-01-08T21:28:00+00:00

Trivial conflict in CAN on file rename.

Conflicts:
	drivers/net/can/m_can/tcan4x5x-core.c

Signed-off-by: Jakub Kicinski

skbuff: Rename skb_zcopy_{get|put} to net_zcopy_{get|put}

2021-01-08T00:08:37+00:00

Unlike the rest of the skb_zcopy_ functions, these routines
operate on a 'struct ubuf', not a skb.  Remove the 'skb_'
prefix from the naming to make things clearer.

Suggested-by: Willem de Bruijn 
Signed-off-by: Jonathan Lemon 
Signed-off-by: Jakub Kicinski

skbuff: rename sock_zerocopy_* to msg_zerocopy_*

2021-01-08T00:08:35+00:00

At Willem's suggestion, rename the sock_zerocopy_* functions
so that they match the MSG_ZEROCOPY flag, which makes it clear
they are specific to this zerocopy implementation.

Signed-off-by: Jonathan Lemon 
Acked-by: Willem de Bruijn 
Signed-off-by: Jakub Kicinski

skbuff: Call sock_zerocopy_put_abort from skb_zcopy_put_abort

2021-01-08T00:06:37+00:00

The sock_zerocopy_put_abort function contains logic which is
specific to the current zerocopy implementation.  Add a wrapper
which checks the callback and dispatches apppropriately.

Signed-off-by: Jonathan Lemon 
Signed-off-by: Jakub Kicinski

net: ip: always refragment ip defragmented packets

2021-01-07T22:42:36+00:00

Conntrack reassembly records the largest fragment size seen in IPCB.
However, when this gets forwarded/transmitted, fragmentation will only
be forced if one of the fragmented packets had the DF bit set.

In that case, a flag in IPCB will force fragmentation even if the
MTU is large enough.

This should work fine, but this breaks with ip tunnels.
Consider client that sends a UDP datagram of size X to another host.

The client fragments the datagram, so two packets, of size y and z, are
sent. DF bit is not set on any of these packets.

Middlebox netfilter reassembles those packets back to single size-X
packet, before routing decision.

packet-size-vs-mtu checks in ip_forward are irrelevant, because DF bit
isn't set.  At output time, ip refragmentation is skipped as well
because x is still smaller than the mtu of the output device.

If ttransmit device is an ip tunnel, the packet size increases to
x+overhead.

Also, tunnel might be configured to force DF bit on outer header.

In this case, packet will be dropped (exceeds MTU) and an ICMP error is
generated back to sender.

But sender already respects the announced MTU, all the packets that
it sent did fit the announced mtu.

Force refragmentation as per original sizes unconditionally so ip tunnel
will encapsulate the fragments instead.

The only other solution I see is to place ip refragmentation in
the ip_tunnel code to handle this case.

Fixes: d6b915e29f4ad ("ip_fragment: don't forward defragmented DF packet")
Reported-by: Christian Perle 
Signed-off-by: Florian Westphal 
Acked-by: Pablo Neira Ayuso 
Signed-off-by: Jakub Kicinski

lsm,selinux: pass flowi_common instead of flowi to the LSM hooks

2020-11-23T23:36:21+00:00

As pointed out by Herbert in a recent related patch, the LSM hooks do
not have the necessary address family information to use the flowi
struct safely.  As none of the LSMs currently use any of the protocol
specific flowi information, replace the flowi pointers with pointers
to the address family independent flowi_common struct.

Reported-by: Herbert Xu 
Acked-by: James Morris 
Signed-off-by: Paul Moore