net: core: Support UID-based routing.

This contains the following commits:

1. 0149763 net: core: Add a UID range to fib rules.
2. 1650474 net: core: Use the socket UID in routing lookups.
3. 0b16771 net: ipv4: Add the UID to the route cache.
4. ee058f1 net: core: Add a RTA_UID attribute to routes.
    This is so that userspace can do per-UID route lookups.

Bug: 15413527
Change-Id: I1285474c6734614d3bda6f61d88dfe89a4af7892
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Git-commit: 0b428749ce5969bc06c73855e360141b4e7126e8
Git-repo: https://android.googlesource.com/kernel/common.git
Signed-off-by: Ian Maund <imaund@codeaurora.org>
diff --git a/include/net/fib_rules.h b/include/net/fib_rules.h
index 075f1e3..52e77a3 100644
--- a/include/net/fib_rules.h
+++ b/include/net/fib_rules.h
@@ -23,6 +23,8 @@
 	struct fib_rule __rcu	*ctarget;
 	char			iifname[IFNAMSIZ];
 	char			oifname[IFNAMSIZ];
+	uid_t			uid_start;
+	uid_t			uid_end;
 	struct rcu_head		rcu;
 	struct net *		fr_net;
 };
@@ -79,7 +81,9 @@
 	[FRA_FWMARK]	= { .type = NLA_U32 }, \
 	[FRA_FWMASK]	= { .type = NLA_U32 }, \
 	[FRA_TABLE]     = { .type = NLA_U32 }, \
-	[FRA_GOTO]	= { .type = NLA_U32 }
+	[FRA_GOTO]	= { .type = NLA_U32 }, \
+	[FRA_UID_START]	= { .type = NLA_U32 }, \
+	[FRA_UID_END]	= { .type = NLA_U32 }
 
 static inline void fib_rule_get(struct fib_rule *rule)
 {
diff --git a/include/net/flow.h b/include/net/flow.h
index 6c469db..3fe9261 100644
--- a/include/net/flow.h
+++ b/include/net/flow.h
@@ -23,6 +23,7 @@
 #define FLOWI_FLAG_PRECOW_METRICS	0x02
 #define FLOWI_FLAG_CAN_SLEEP		0x04
 	__u32	flowic_secid;
+	uid_t	flowic_uid;
 };
 
 union flowi_uli {
@@ -59,6 +60,7 @@
 #define flowi4_proto		__fl_common.flowic_proto
 #define flowi4_flags		__fl_common.flowic_flags
 #define flowi4_secid		__fl_common.flowic_secid
+#define flowi4_uid		__fl_common.flowic_uid
 
 	/* (saddr,daddr) must be grouped, same order as in IP header */
 	__be32			saddr;
@@ -78,7 +80,8 @@
 				      __u32 mark, __u8 tos, __u8 scope,
 				      __u8 proto, __u8 flags,
 				      __be32 daddr, __be32 saddr,
-				      __be16 dport, __be16 sport)
+				      __be16 dport, __be16 sport,
+				      uid_t uid)
 {
 	fl4->flowi4_oif = oif;
 	fl4->flowi4_iif = 0;
@@ -88,6 +91,7 @@
 	fl4->flowi4_proto = proto;
 	fl4->flowi4_flags = flags;
 	fl4->flowi4_secid = 0;
+	fl4->flowi4_uid = uid;
 	fl4->daddr = daddr;
 	fl4->saddr = saddr;
 	fl4->fl4_dport = dport;
@@ -115,6 +119,7 @@
 #define flowi6_proto		__fl_common.flowic_proto
 #define flowi6_flags		__fl_common.flowic_flags
 #define flowi6_secid		__fl_common.flowic_secid
+#define flowi6_uid		__fl_common.flowic_uid
 	struct in6_addr		daddr;
 	struct in6_addr		saddr;
 	__be32			flowlabel;
@@ -158,6 +163,7 @@
 #define flowi_proto	u.__fl_common.flowic_proto
 #define flowi_flags	u.__fl_common.flowic_flags
 #define flowi_secid	u.__fl_common.flowic_secid
+#define flowi_uid	u.__fl_common.flowic_uid
 } __attribute__((__aligned__(BITS_PER_LONG/8)));
 
 static inline struct flowi *flowi4_to_flowi(struct flowi4 *fl4)
diff --git a/include/net/ip.h b/include/net/ip.h
index b53d65f..53af759 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -166,6 +166,7 @@
 				/* -1 if not needed */ 
 	int	    bound_dev_if;
 	u8  	    tos;
+	uid_t	    uid;
 }; 
 
 #define IP_REPLY_ARG_NOSRCCHECK 1
diff --git a/include/net/route.h b/include/net/route.h
index b1c0d5b..335466d 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -60,6 +60,7 @@
 	int			rt_iif;
 	int			rt_oif;
 	__u32			rt_mark;
+	uid_t			rt_uid;
 
 	/* Info on neighbour */
 	__be32			rt_gateway;
@@ -146,7 +147,7 @@
 	flowi4_init_output(fl4, oif, sk ? sk->sk_mark : 0, tos,
 			   RT_SCOPE_UNIVERSE, proto,
 			   sk ? inet_sk_flowi_flags(sk) : 0,
-			   daddr, saddr, dport, sport);
+			   daddr, saddr, dport, sport, sock_i_uid(sk));
 	if (sk)
 		security_sk_classify_flow(sk, flowi4_to_flowi(fl4));
 	return ip_route_output_flow(net, fl4, sk);
@@ -250,7 +251,8 @@
 		flow_flags |= FLOWI_FLAG_CAN_SLEEP;
 
 	flowi4_init_output(fl4, oif, sk->sk_mark, tos, RT_SCOPE_UNIVERSE,
-			   protocol, flow_flags, dst, src, dport, sport);
+			   protocol, flow_flags, dst, src, dport, sport,
+			   sock_i_uid(sk));
 }
 
 static inline struct rtable *ip_route_connect(struct flowi4 *fl4,