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Filename Latest commit message Latest commit date
Mathieu Desnoyers 295501c77c ipv4/icmp: l3mdev: Perform icmp error route lookup on source device routing table (v2)
commit e1e84eb58eb494b77c8389fc6308b5042dcce791 upstream.

As per RFC792, ICMP errors should be sent to the source host.

However, in configurations with Virtual Routing and Forwarding tables,
looking up which routing table to use is currently done by using the
destination net_device.

commit 9d1a6c4ea4 ("net: icmp_route_lookup should use rt dev to
determine L3 domain") changes the interface passed to
l3mdev_master_ifindex() and inet_addr_type_dev_table() from skb_in->dev
to skb_dst(skb_in)->dev. This effectively uses the destination device
rather than the source device for choosing which routing table should be
used to lookup where to send the ICMP error.

Therefore, if the source and destination interfaces are within separate
VRFs, or one in the global routing table and the other in a VRF, looking
up the source host in the destination interface's routing table will
fail if the destination interface's routing table contains no route to
the source host.

One observable effect of this issue is that traceroute does not work in
the following cases:

- Route leaking between global routing table and VRF
- Route leaking between VRFs

Preferably use the source device routing table when sending ICMP error
messages. If no source device is set, fall-back on the destination
device routing table. Else, use the main routing table (index 0).

[ It has been pointed out that a similar issue may exist with ICMP
  errors triggered when forwarding between network namespaces. It would
  be worthwhile to investigate, but is outside of the scope of this
  investigation. ]

[ It has also been pointed out that a similar issue exists with
  unreachable / fragmentation needed messages, which can be triggered by
  changing the MTU of eth1 in r1 to 1400 and running:

  ip netns exec h1 ping -s 1450 -Mdo -c1 172.16.2.2

  Some investigation points to raw_icmp_error() and raw_err() as being
  involved in this last scenario. The focus of this patch is TTL expired
  ICMP messages, which go through icmp_route_lookup.
  Investigation of failure modes related to raw_icmp_error() is beyond
  this investigation's scope. ]

Fixes: 9d1a6c4ea4 ("net: icmp_route_lookup should use rt dev to determine L3 domain")
Link: https://tools.ietf.org/html/rfc792
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-09-12 08:56:40 +02:00
arch ARC: wireup clone3 syscall 2021-09-12 08:56:40 +02:00
block blk-iolatency: error out if blk_get_queue() failed in iolatency_set_limit() 2021-08-12 13:20:58 +02:00
certs certs: Move load_system_certificate_list to a common function 2021-06-30 08:47:55 -04:00
crypto crypto: shash - avoid comparing pointers to exported functions under CFI 2021-07-14 16:53:13 +02:00
Documentation KVM: X86: MMU: Use the correct inherited permissions to get shadow page 2021-08-15 13:08:04 +02:00
drivers USB: serial: mos7720: improve OOM-handling in read_mos_reg() 2021-09-12 08:56:40 +02:00
fs ubifs: report correct st_size for encrypted symlinks 2021-09-12 08:56:39 +02:00
include fscrypt: add fscrypt_symlink_getattr() for computing st_size 2021-09-12 08:56:38 +02:00
init kbuild: add CONFIG_LD_IS_LLD 2021-06-30 08:47:44 -04:00
ipc
kernel kthread: Fix PF_KTHREAD vs to_kthread() race 2021-09-12 08:56:39 +02:00
lib once: Fix panic when module unload 2021-09-03 10:08:12 +02:00
LICENSES
mm mm, oom: make the calculation of oom badness more accurate 2021-09-03 10:08:12 +02:00
net ipv4/icmp: l3mdev: Perform icmp error route lookup on source device routing table (v2) 2021-09-12 08:56:40 +02:00
samples samples/bpf: Fix the error return code of xdp_redirect's main() 2021-07-14 16:53:30 +02:00
scripts scripts/tracing: fix the bug that can't parse raw_trace_func 2021-08-12 13:21:00 +02:00
security smackfs: restrict bytes count in smk_set_cipso() 2021-07-19 08:53:18 +02:00
sound ALSA: pcm: fix divide error in snd_pcm_lib_ioctl 2021-09-12 08:56:40 +02:00
tools bpf, selftests: Adjust few selftest result_unpriv outcomes 2021-08-12 13:21:04 +02:00
usr
virt KVM: Do not leak memory for duplicate debugfs directories 2021-08-12 13:21:03 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.144 2021-09-03 10:08:16 +02:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
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    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.