[PATCH] arm: mvebu: Espressobin: Disallow forwarding packets between wan and lan ports

[Pali Rohár]

By default Topaz switch on Espressobin board forwards packets between all
ethernet ports, including CPU (port 0), wan (port 1) and lan (ports 2,3).

This default U-Boot setup is unsuitable for using Espressobin as router as
it opens security hole in forwarding all packets between wan and lan ports.
E.g. dhcp packets from wan network leaks to lan network during small time
window until U-Boot boots Linux kernel which loads network drivers which
disallows forwarding between wan and lan.

This patch fixes above problem. For Espressobin board prior putting Topaz
switch into forwarding mode, Topaz switch is reconfigured to allow
forwarding packets from wan and lan ports only to CPU port. This ensures
that packets from wan port are not forwarded to lan ports and vice-versa.
Packets from CPU port are still forwarded to all other ports, so U-Boot
network boot works with any ethernet port as before.

This problem was already discussed on Espressobin forum [1] and on
Marvell's github issue tracker [2]. As a workaround people on Espressobin
forum patched U-Boot to completely disable lan ports on Topaz switch which
prevented forwarding packets. That workaround had an issue that U-Boot was
unable to netboot via lan ports anymore. Change in this patch does not have
such issue.

[1] - https://web.archive.org/web/20191231164238/http://espressobin.net/forums/topic/boot-behavior-of-the-switch-and-security/
[2] - https://github.com/MarvellEmbeddedProcessors/u-boot-marvell/issues/18

Signed-off-by: Pali Rohár <pali at kernel.org>
---
 board/Marvell/mvebu_armada-37xx/board.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/board/Marvell/mvebu_armada-37xx/board.c b/board/Marvell/mvebu_armada-37xx/board.c
index 9bea1986d4..031de318c6 100644
--- a/board/Marvell/mvebu_armada-37xx/board.c
+++ b/board/Marvell/mvebu_armada-37xx/board.c
@@ -37,20 +37,21 @@ DECLARE_GLOBAL_DATA_PTR;
  #define SW_SMI_CMD_REG_ADDR_OFF	0
  #define SW_SMI_CMD_DEV_ADDR_OFF	5
  #define SW_SMI_CMD_SMI_OP_OFF		10
  #define SW_SMI_CMD_SMI_MODE_OFF	12
  #define SW_SMI_CMD_SMI_BUSY_OFF	15
 
 /* Single-chip mode */
 /* Switch Port Registers */
 #define MVEBU_SW_LINK_CTRL_REG		(1)
 #define MVEBU_SW_PORT_CTRL_REG		(4)
+#define MVEBU_SW_PORT_BASE_VLAN		(6)
 
 /* Global 2 Registers */
 #define MVEBU_G2_SMI_PHY_CMD_REG	(24)
 #define MVEBU_G2_SMI_PHY_DATA_REG	(25)
 
 int board_early_init_f(void)
 {
 	return 0;
 }
 
@@ -200,22 +201,30 @@ static int mii_multi_chip_mode_write(struct mii_dev *bus, int dev_smi_addr,
 /* Bring-up board-specific network stuff */
 int board_network_enable(struct mii_dev *bus)
 {
 	if (!of_machine_is_compatible("marvell,armada-3720-espressobin"))
 		return 0;
 
 	/*
 	 * FIXME: remove this code once Topaz driver gets available
 	 * A3720 Community Board Only
 	 * Configure Topaz switch (88E6341)
+	 * Restrict output to ports 1,2,3 only from port 0 (CPU)
 	 * Set port 0,1,2,3 to forwarding Mode (through Switch Port registers)
 	 */
+	mii_multi_chip_mode_write(bus, 1, MVEBU_PORT_CTRL_SMI_ADDR(1),
+				  MVEBU_SW_PORT_BASE_VLAN, BIT(0));
+	mii_multi_chip_mode_write(bus, 1, MVEBU_PORT_CTRL_SMI_ADDR(2),
+				  MVEBU_SW_PORT_BASE_VLAN, BIT(0));
+	mii_multi_chip_mode_write(bus, 1, MVEBU_PORT_CTRL_SMI_ADDR(3),
+				  MVEBU_SW_PORT_BASE_VLAN, BIT(0));
+
 	mii_multi_chip_mode_write(bus, 1, MVEBU_PORT_CTRL_SMI_ADDR(0),
 				  MVEBU_SW_PORT_CTRL_REG, 0x7f);
 	mii_multi_chip_mode_write(bus, 1, MVEBU_PORT_CTRL_SMI_ADDR(1),
 				  MVEBU_SW_PORT_CTRL_REG, 0x7f);
 	mii_multi_chip_mode_write(bus, 1, MVEBU_PORT_CTRL_SMI_ADDR(2),
 				  MVEBU_SW_PORT_CTRL_REG, 0x7f);
 	mii_multi_chip_mode_write(bus, 1, MVEBU_PORT_CTRL_SMI_ADDR(3),
 				  MVEBU_SW_PORT_CTRL_REG, 0x7f);
 
 	/* RGMII Delay on Port 0 (CPU port), force link to 1000Mbps */
-- 
2.20.1