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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Guillaume Nault <gnault@redhat.com>,
	"David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.9 10/45] ipv4: Ignore ECN bits for fib lookups in fib_compute_spec_dst()
Date: Mon, 11 Jan 2021 14:00:48 +0100	[thread overview]
Message-ID: <20210111130034.158968081@linuxfoundation.org> (raw)
In-Reply-To: <20210111130033.676306636@linuxfoundation.org>

From: Guillaume Nault <gnault@redhat.com>

[ Upstream commit 21fdca22eb7df2a1e194b8adb812ce370748b733 ]

RT_TOS() only clears one of the ECN bits. Therefore, when
fib_compute_spec_dst() resorts to a fib lookup, it can return
different results depending on the value of the second ECN bit.

For example, ECT(0) and ECT(1) packets could be treated differently.

  $ ip netns add ns0
  $ ip netns add ns1
  $ ip link add name veth01 netns ns0 type veth peer name veth10 netns ns1
  $ ip -netns ns0 link set dev lo up
  $ ip -netns ns1 link set dev lo up
  $ ip -netns ns0 link set dev veth01 up
  $ ip -netns ns1 link set dev veth10 up

  $ ip -netns ns0 address add 192.0.2.10/24 dev veth01
  $ ip -netns ns1 address add 192.0.2.11/24 dev veth10

  $ ip -netns ns1 address add 192.0.2.21/32 dev lo
  $ ip -netns ns1 route add 192.0.2.10/32 tos 4 dev veth10 src 192.0.2.21
  $ ip netns exec ns1 sysctl -wq net.ipv4.icmp_echo_ignore_broadcasts=0

With TOS 4 and ECT(1), ns1 replies using source address 192.0.2.21
(ping uses -Q to set all TOS and ECN bits):

  $ ip netns exec ns0 ping -c 1 -b -Q 5 192.0.2.255
  [...]
  64 bytes from 192.0.2.21: icmp_seq=1 ttl=64 time=0.544 ms

But with TOS 4 and ECT(0), ns1 replies using source address 192.0.2.11
because the "tos 4" route isn't matched:

  $ ip netns exec ns0 ping -c 1 -b -Q 6 192.0.2.255
  [...]
  64 bytes from 192.0.2.11: icmp_seq=1 ttl=64 time=0.597 ms

After this patch the ECN bits don't affect the result anymore:

  $ ip netns exec ns0 ping -c 1 -b -Q 6 192.0.2.255
  [...]
  64 bytes from 192.0.2.21: icmp_seq=1 ttl=64 time=0.591 ms

Fixes: 35ebf65e851c ("ipv4: Create and use fib_compute_spec_dst() helper.")
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/ipv4/fib_frontend.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -292,7 +292,7 @@ __be32 fib_compute_spec_dst(struct sk_bu
 			.flowi4_iif = LOOPBACK_IFINDEX,
 			.flowi4_oif = l3mdev_master_ifindex_rcu(dev),
 			.daddr = ip_hdr(skb)->saddr,
-			.flowi4_tos = RT_TOS(ip_hdr(skb)->tos),
+			.flowi4_tos = ip_hdr(skb)->tos & IPTOS_RT_MASK,
 			.flowi4_scope = scope,
 			.flowi4_mark = vmark ? skb->mark : 0,
 		};



  parent reply	other threads:[~2021-01-11 14:09 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-11 13:00 [PATCH 4.9 00/45] 4.9.251-rc1 review Greg Kroah-Hartman
2021-01-11 13:00 ` [PATCH 4.9 01/45] kbuild: dont hardcode depmod path Greg Kroah-Hartman
2021-01-11 13:00 ` [PATCH 4.9 02/45] workqueue: Kick a worker based on the actual activation of delayed works Greg Kroah-Hartman
2021-01-11 13:00 ` [PATCH 4.9 03/45] lib/genalloc: fix the overflow when size is too big Greg Kroah-Hartman
2021-01-11 13:00 ` [PATCH 4.9 04/45] depmod: handle the case of /sbin/depmod without /sbin in PATH Greg Kroah-Hartman
2021-01-11 13:00 ` [PATCH 4.9 05/45] ethernet: ucc_geth: fix use-after-free in ucc_geth_remove() Greg Kroah-Hartman
2021-01-11 13:00 ` [PATCH 4.9 06/45] atm: idt77252: call pci_disable_device() on error path Greg Kroah-Hartman
2021-01-11 13:00 ` [PATCH 4.9 07/45] net: dcb: Validate netlink message in DCB handler Greg Kroah-Hartman
2021-01-11 13:00 ` [PATCH 4.9 08/45] net/ncsi: Use real net-device for response handler Greg Kroah-Hartman
2021-01-11 13:00 ` [PATCH 4.9 09/45] net: ethernet: Fix memleak in ethoc_probe Greg Kroah-Hartman
2021-01-11 13:00 ` Greg Kroah-Hartman [this message]
2021-01-11 13:00 ` [PATCH 4.9 11/45] net: hns: fix return value check in __lb_other_process() Greg Kroah-Hartman
2021-01-11 13:00 ` [PATCH 4.9 12/45] net: hdlc_ppp: Fix issues when mod_timer is called while timer is running Greg Kroah-Hartman
2021-01-11 13:00 ` [PATCH 4.9 13/45] CDC-NCM: remove "connected" log message Greg Kroah-Hartman
2021-01-11 13:00 ` [PATCH 4.9 14/45] vhost_net: fix ubuf refcount incorrectly when sendmsg fails Greg Kroah-Hartman
2021-01-11 13:00 ` [PATCH 4.9 15/45] net: sched: prevent invalid Scell_log shift count Greg Kroah-Hartman
2021-01-11 13:00 ` [PATCH 4.9 16/45] virtio_net: Fix recursive call to cpus_read_lock() Greg Kroah-Hartman
2021-01-11 13:00 ` [PATCH 4.9 17/45] scripts/gdb: make lx-dmesg command work (reliably) Greg Kroah-Hartman
2021-01-11 13:00 ` [PATCH 4.9 18/45] scripts/gdb: lx-dmesg: cast log_buf to void* for addr fetch Greg Kroah-Hartman
2021-01-11 13:00 ` [PATCH 4.9 19/45] scripts/gdb: lx-dmesg: use explicit encoding=utf8 errors=replace Greg Kroah-Hartman
2021-01-11 13:00 ` [PATCH 4.9 20/45] scripts/gdb: fix lx-version string output Greg Kroah-Hartman
2021-01-11 13:00 ` [PATCH 4.9 21/45] video: hyperv_fb: Fix the mmap() regression for v5.4.y and older Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 22/45] usb: gadget: enable super speed plus Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 23/45] USB: cdc-acm: blacklist another IR Droid device Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 24/45] usb: chipidea: ci_hdrc_imx: add missing put_device() call in usbmisc_get_init_data() Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 25/45] USB: xhci: fix U1/U2 handling for hardware with XHCI_INTEL_HOST quirk set Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 26/45] usb: uas: Add PNY USB Portable SSD to unusual_uas Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 27/45] USB: serial: iuu_phoenix: fix DMA from stack Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 28/45] USB: serial: option: add LongSung M5710 module support Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 29/45] USB: yurex: fix control-URB timeout handling Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 30/45] USB: usblp: fix DMA to stack Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 31/45] ALSA: usb-audio: Fix UBSAN warnings for MIDI jacks Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 32/45] usb: gadget: select CONFIG_CRC32 Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 33/45] usb: gadget: f_uac2: reset wMaxPacketSize Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 34/45] usb: gadget: function: printer: Fix a memory leak for interface descriptor Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 35/45] USB: gadget: legacy: fix return error code in acm_ms_bind() Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 36/45] usb: gadget: Fix spinlock lockup on usb_function_deactivate Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 37/45] usb: gadget: configfs: Preserve function ordering after bind failure Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 38/45] usb: gadget: configfs: Fix use-after-free issue with udc_name Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 39/45] USB: serial: keyspan_pda: remove unused variable Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 40/45] x86/mm: Fix leak of pmd ptlock Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 41/45] ALSA: hda/conexant: add a new hda codec CX11970 Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 42/45] Revert "device property: Keep secondary firmware node secondary by type" Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 43/45] netfilter: ipset: fix shift-out-of-bounds in htable_bits() Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 44/45] netfilter: xt_RATEEST: reject non-null terminated string from userspace Greg Kroah-Hartman
2021-01-11 13:01 ` [PATCH 4.9 45/45] x86/mtrr: Correct the range check before performing MTRR type lookups Greg Kroah-Hartman
2021-01-11 21:52 ` [PATCH 4.9 00/45] 4.9.251-rc1 review Guenter Roeck
2021-01-11 23:40 ` Shuah Khan
2021-01-12  8:16 ` Naresh Kamboju

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