netifd: Add rpfilter config support

Reverse path filtering config support; possible values are:
    0: no source validation
    1|strict: strict mode as packet will be dropped if the
    incoming interface is not the best reverse path
    2|loose: loose mode as packet will be dropped if the
    source address is not reachable via any interface

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>

5 files changed, 62 insertions, 0 deletions

diff --git a/device.c b/device.c
index 5d1dcac..d261e25 100644
--- a/device.c
+++ b/device.c
@@ -39,6 +39,7 @@ static const struct blobmsg_policy dev_attrs[__DEV_ATTR_MAX] = {
 	[DEV_ATTR_ENABLED] = { .name = "enabled", .type = BLOBMSG_TYPE_BOOL },
 	[DEV_ATTR_IPV6] = { .name = "ipv6", .type = BLOBMSG_TYPE_BOOL },
 	[DEV_ATTR_PROMISC] = { .name = "promisc", .type = BLOBMSG_TYPE_BOOL },
+	[DEV_ATTR_RPFILTER] = { .name = "rpfilter", .type = BLOBMSG_TYPE_STRING },
 };
 
 const struct uci_blob_param_list device_attr_list = {
@@ -154,6 +155,7 @@ device_merge_settings(struct device *dev, struct device_settings *n)
 		sizeof(n->macaddr));
 	n->ipv6 = s->flags & DEV_OPT_IPV6 ? s->ipv6 : os->ipv6;
 	n->promisc = s->flags & DEV_OPT_PROMISC ? s->promisc : os->promisc;
+	n->rpfilter = s->flags & DEV_OPT_RPFILTER ? s->rpfilter : os->rpfilter;
 	n->flags = s->flags | os->flags;
 }
 
@@ -197,6 +199,13 @@ device_init_settings(struct device *dev, struct blob_attr **tb)
 		s->flags |= DEV_OPT_PROMISC;
 	}
 
+	if ((cur = tb[DEV_ATTR_RPFILTER])) {
+		if (system_resolve_rpfilter(blobmsg_data(cur), &s->rpfilter))
+			s->flags |= DEV_OPT_RPFILTER;
+		else
+			DPRINTF("Failed to resolve rpfilter: %s\n", (char *) blobmsg_data(cur));
+	}
+
 	device_set_disabled(dev, disabled);
 }
 
@@ -734,6 +743,8 @@ device_dump_status(struct blob_buf *b, struct device *dev)
 			blobmsg_add_u8(b, "ipv6", st.ipv6);
 		if (st.flags & DEV_OPT_PROMISC)
 			blobmsg_add_u8(b, "promisc", st.promisc);
+		if (st.flags & DEV_OPT_RPFILTER)
+			blobmsg_add_u32(b, "rpfilter", st.rpfilter);
 	}
 
 	s = blobmsg_open_table(b, "statistics");
diff --git a/device.h b/device.h
index adf72c5..0af65be 100644
--- a/device.h
+++ b/device.h
@@ -33,6 +33,7 @@ enum {
 	DEV_ATTR_ENABLED,
 	DEV_ATTR_IPV6,
 	DEV_ATTR_PROMISC,
+	DEV_ATTR_RPFILTER,
 	__DEV_ATTR_MAX,
 };
 
@@ -66,6 +67,7 @@ enum {
 	DEV_OPT_TXQUEUELEN	= (1 << 2),
 	DEV_OPT_IPV6		= (1 << 3),
 	DEV_OPT_PROMISC		= (1 << 4),
+	DEV_OPT_RPFILTER	= (1 << 5),
 };
 
 /* events broadcasted to all users of a device */
@@ -113,6 +115,7 @@ struct device_settings {
 	uint8_t macaddr[6];
 	bool ipv6;
 	bool promisc;
+	unsigned int rpfilter;
 };
 
 /*
diff --git a/system-dummy.c b/system-dummy.c
index 7d54315..76c6ffa 100644
--- a/system-dummy.c
+++ b/system-dummy.c
@@ -209,6 +209,12 @@ bool system_is_default_rt_table(unsigned int id)
 	return true;
 }
 
+bool system_resolve_rpfilter(const char *filter, unsigned int *id)
+{
+	*id = 0;
+	return true;
+}
+
 int system_add_iprule(struct iprule *rule)
 {
 	return 0;
diff --git a/system-linux.c b/system-linux.c
index 01c3deb..bb7ccf9 100644
--- a/system-linux.c
+++ b/system-linux.c
@@ -265,6 +265,11 @@ static void system_set_disable_ipv6(struct device *dev, const char *val)
 	system_set_dev_sysctl("/proc/sys/net/ipv6/conf/%s/disable_ipv6", dev->ifname, val);
 }
 
+static void system_set_rpfilter(struct device *dev, const char *val)
+{
+	system_set_dev_sysctl("/proc/sys/net/ipv4/conf/%s/rp_filter", dev->ifname, val);
+}
+
 static int system_get_sysctl(const char *path, char *buf, const size_t buf_sz)
 {
 	int fd = -1, ret = -1;
@@ -299,6 +304,12 @@ static int system_get_disable_ipv6(struct device *dev, char *buf, const size_t b
 			dev->ifname, buf, buf_sz);
 }
 
+static int system_get_rpfilter(struct device *dev, char *buf, const size_t buf_sz)
+{
+	return system_get_dev_sysctl("/proc/sys/net/ipv4/conf/%s/rp_filter",
+			dev->ifname, buf, buf_sz);
+}
+
 // Evaluate netlink messages
 static int cb_rtnl_event(struct nl_msg *msg, void *arg)
 {
@@ -953,6 +964,11 @@ system_if_get_settings(struct device *dev, struct device_settings *s)
 		s->promisc = ifr.ifr_flags & IFF_PROMISC;
 		s->flags |= DEV_OPT_PROMISC;
 	}
+
+	if (!system_get_rpfilter(dev, buf, sizeof(buf))) {
+		s->rpfilter = strtoul(buf, NULL, 0);
+		s->flags |= DEV_OPT_RPFILTER;
+	}
 }
 
 void
@@ -988,6 +1004,12 @@ system_if_apply_settings(struct device *dev, struct device_settings *s, unsigned
 				    !s->promisc ? IFF_PROMISC : 0) < 0)
 			s->flags &= ~DEV_OPT_PROMISC;
 	}
+	if (s->flags & DEV_OPT_RPFILTER & apply_mask) {
+		char buf[2];
+
+		snprintf(buf, sizeof(buf), "%d", s->rpfilter);
+		system_set_rpfilter(dev, buf);
+	}
 }
 
 int system_if_up(struct device *dev)
@@ -1506,6 +1528,25 @@ bool system_is_default_rt_table(unsigned int id)
 	return (id == RT_TABLE_MAIN);
 }
 
+bool system_resolve_rpfilter(const char *filter, unsigned int *id)
+{
+	char *e;
+	unsigned int n;
+
+	if (!strcmp(filter, "strict"))
+		n = 1;
+	else if (!strcmp(filter, "loose"))
+		n = 2;
+	else {
+		n = strtoul(filter, &e, 0);
+		if (*e || e == filter || n > 2)
+			return false;
+	}
+
+	*id = n;
+	return true;
+}
+
 static int system_iprule(struct iprule *rule, int cmd)
 {
 	int alen = ((rule->flags & IPRULE_FAMILY) == IPRULE_INET4) ? 4 : 16;
diff --git a/system.h b/system.h
index 3bf6f97..9a2326b 100644
--- a/system.h
+++ b/system.h
@@ -135,6 +135,7 @@ int system_flush_routes(void);
 bool system_resolve_rt_type(const char *type, unsigned int *id);
 bool system_resolve_rt_table(const char *name, unsigned int *id);
 bool system_is_default_rt_table(unsigned int id);
+bool system_resolve_rpfilter(const char *filter, unsigned int *id);
 
 int system_del_ip_tunnel(const char *name, struct blob_attr *attr);
 int system_add_ip_tunnel(const char *name, struct blob_attr *attr);