sandbox: eth: Add a bridge to a real network for sandbox

Implement a bridge between U-Boot's network stack and Linux's raw packet
API allowing the sandbox to send and receive packets using the host
machine's network interface.

This raw Ethernet API requires elevated privileges.  You can either run
as root, or you can add the capability needed like so:

sudo /sbin/setcap "CAP_NET_RAW+ep" /path/to/u-boot

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

2 files changed, 150 insertions, 0 deletions

diff --git a/arch/sandbox/cpu/Makefile b/arch/sandbox/cpu/Makefile
index 7d4410c..1b42fee 100644
--- a/arch/sandbox/cpu/Makefile
+++ b/arch/sandbox/cpu/Makefile
@@ -8,6 +8,7 @@
 #
 
 obj-y	:= cpu.o os.o start.o state.o
+obj-$(CONFIG_ETH_SANDBOX_RAW)	+= eth-raw-os.o
 obj-$(CONFIG_SANDBOX_SDL)	+= sdl.o
 
 # os.c is build in the system environment, so needs standard includes
@@ -20,3 +21,12 @@ $(obj)/os.o: $(src)/os.c FORCE
 	$(call if_changed_dep,cc_os.o)
 $(obj)/sdl.o: $(src)/sdl.c FORCE
 	$(call if_changed_dep,cc_os.o)
+
+# eth-raw-os.c is built in the system env, so needs standard includes
+# CFLAGS_REMOVE_eth-raw-os.o cannot be used to drop header include path
+quiet_cmd_cc_eth-raw-os.o = CC $(quiet_modtag)  $@
+cmd_cc_eth-raw-os.o = $(CC) $(filter-out -nostdinc, \
+	$(patsubst -I%,-idirafter%,$(c_flags))) -c -o $@ $<
+
+$(obj)/eth-raw-os.o: $(src)/eth-raw-os.c FORCE
+	$(call if_changed_dep,cc_eth-raw-os.o)
diff --git a/arch/sandbox/cpu/eth-raw-os.c b/arch/sandbox/cpu/eth-raw-os.c
new file mode 100644
index 0000000..601205a
--- /dev/null
+++ b/arch/sandbox/cpu/eth-raw-os.c
@@ -0,0 +1,140 @@
+/*
+ * Copyright (c) 2015 National Instruments
+ *
+ * (C) Copyright 2015
+ * Joe Hershberger <joe.hershberger@ni.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ */
+
+#include <asm/eth-raw-os.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <net/if.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+#include <linux/if_ether.h>
+#include <linux/if_packet.h>
+
+int sandbox_eth_raw_os_start(const char *ifname, unsigned char *ethmac,
+			    struct eth_sandbox_raw_priv *priv)
+{
+	struct sockaddr_ll *device;
+	struct packet_mreq mr;
+	int ret;
+	int flags;
+
+	/* Prepare device struct */
+	priv->device = malloc(sizeof(struct sockaddr_ll));
+	if (priv->device == NULL)
+		return -ENOMEM;
+	device = priv->device;
+	memset(device, 0, sizeof(struct sockaddr_ll));
+	device->sll_ifindex = if_nametoindex(ifname);
+	device->sll_family = AF_PACKET;
+	memcpy(device->sll_addr, ethmac, 6);
+	device->sll_halen = htons(6);
+
+	/* Open socket */
+	priv->sd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
+	if (priv->sd < 0) {
+		printf("Failed to open socket: %d %s\n", errno,
+		       strerror(errno));
+		return -errno;
+	}
+	/* Bind to the specified interface */
+	ret = setsockopt(priv->sd, SOL_SOCKET, SO_BINDTODEVICE, ifname,
+		   strlen(ifname) + 1);
+	if (ret < 0) {
+		printf("Failed to bind to '%s': %d %s\n", ifname, errno,
+		       strerror(errno));
+		return -errno;
+	}
+
+	/* Make the socket non-blocking */
+	flags = fcntl(priv->sd, F_GETFL, 0);
+	fcntl(priv->sd, F_SETFL, flags | O_NONBLOCK);
+
+	/* Enable promiscuous mode to receive responses meant for us */
+	mr.mr_ifindex = device->sll_ifindex;
+	mr.mr_type = PACKET_MR_PROMISC;
+	ret = setsockopt(priv->sd, SOL_PACKET, PACKET_ADD_MEMBERSHIP,
+		   &mr, sizeof(mr));
+	if (ret < 0) {
+		struct ifreq ifr;
+
+		printf("Failed to set promiscuous mode: %d %s\n"
+		       "Falling back to the old \"flags\" way...\n",
+			errno, strerror(errno));
+		strncpy(ifr.ifr_name, ifname, IFNAMSIZ);
+		if (ioctl(priv->sd, SIOCGIFFLAGS, &ifr) < 0) {
+			printf("Failed to read flags: %d %s\n", errno,
+			       strerror(errno));
+			return -errno;
+		}
+		ifr.ifr_flags |= IFF_PROMISC;
+		if (ioctl(priv->sd, SIOCSIFFLAGS, &ifr) < 0) {
+			printf("Failed to write flags: %d %s\n", errno,
+			       strerror(errno));
+			return -errno;
+		}
+	}
+	return 0;
+}
+
+int sandbox_eth_raw_os_send(void *packet, int length,
+			    const struct eth_sandbox_raw_priv *priv)
+{
+	int retval;
+
+	if (!priv->sd || !priv->device)
+		return -EINVAL;
+
+	retval = sendto(priv->sd, packet, length, 0,
+			(struct sockaddr *)priv->device,
+			sizeof(struct sockaddr_ll));
+	if (retval < 0) {
+		printf("Failed to send packet: %d %s\n", errno,
+		       strerror(errno));
+		return -errno;
+	}
+	return retval;
+}
+
+int sandbox_eth_raw_os_recv(void *packet, int *length,
+			    const struct eth_sandbox_raw_priv *priv)
+{
+	int retval;
+	int saddr_size;
+
+	if (!priv->sd || !priv->device)
+		return -EINVAL;
+	saddr_size = sizeof(struct sockaddr);
+	retval = recvfrom(priv->sd, packet, 1536, 0,
+			  (struct sockaddr *)priv->device,
+			  (socklen_t *)&saddr_size);
+	*length = 0;
+	if (retval >= 0) {
+		*length = retval;
+		return 0;
+	}
+	/* The socket is non-blocking, so expect EAGAIN when there is no data */
+	if (errno == EAGAIN)
+		return 0;
+	return -errno;
+}
+
+void sandbox_eth_raw_os_stop(struct eth_sandbox_raw_priv *priv)
+{
+	free(priv->device);
+	priv->device = NULL;
+	close(priv->sd);
+	priv->sd = -1;
+}