net: core: Support UID-based routing.

This contains the following commits:

1. cc2f522 net: core: Add a UID range to fib rules.
2. d7ed2bd net: core: Use the socket UID in routing lookups.
3. 2f9306a net: core: Add a RTA_UID attribute to routes.
    This is so that userspace can do per-UID route lookups.
4. 8e46efb net: ipv6: Use the UID in IPv6 PMTUD
    IPv4 PMTUD already does this because ipv4_sk_update_pmtu
    uses __build_flow_key, which includes the UID.

Bug: 15413527
Change-Id: I81bd31dae655de9cce7d7a1f9a905dc1c2feba7c
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>

7 files changed, 21 insertions, 5 deletions

diff --git a/include/net/fib_rules.h b/include/net/fib_rules.h
index e361f488242..4ac12e14c6d 100644
--- a/include/net/fib_rules.h
+++ b/include/net/fib_rules.h
@@ -23,6 +23,8 @@ struct fib_rule {
 	struct fib_rule __rcu	*ctarget;
 	char			iifname[IFNAMSIZ];
 	char			oifname[IFNAMSIZ];
+	kuid_t			uid_start;
+	kuid_t			uid_end;
 	struct rcu_head		rcu;
 	struct net *		fr_net;
 };
@@ -80,7 +82,9 @@ struct fib_rules_ops {
 	[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 628e11b98c5..c91e2aae3fb 100644
--- a/include/net/flow.h
+++ b/include/net/flow.h
@@ -10,6 +10,7 @@
 #include <linux/socket.h>
 #include <linux/in6.h>
 #include <linux/atomic.h>
+#include <linux/uidgid.h>
 
 struct flowi_common {
 	int	flowic_oif;
@@ -23,6 +24,7 @@ struct flowi_common {
 #define FLOWI_FLAG_CAN_SLEEP		0x02
 #define FLOWI_FLAG_KNOWN_NH		0x04
 	__u32	flowic_secid;
+	kuid_t	flowic_uid;
 };
 
 union flowi_uli {
@@ -59,6 +61,7 @@ struct flowi4 {
 #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 +81,8 @@ static inline void flowi4_init_output(struct flowi4 *fl4, int oif,
 				      __u32 mark, __u8 tos, __u8 scope,
 				      __u8 proto, __u8 flags,
 				      __be32 daddr, __be32 saddr,
-				      __be16 dport, __be16 sport)
+				      __be16 dport, __be16 sport,
+				      kuid_t uid)
 {
 	fl4->flowi4_oif = oif;
 	fl4->flowi4_iif = 0;
@@ -88,6 +92,7 @@ static inline void flowi4_init_output(struct flowi4 *fl4, int oif,
 	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 +120,7 @@ struct flowi6 {
 #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 +164,7 @@ struct flowi {
 #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 509b8807927..02fc145ecc4 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -153,6 +153,7 @@ struct ip_reply_arg {
 				/* -1 if not needed */ 
 	int	    bound_dev_if;
 	u8  	    tos;
+	kuid_t	    uid;
 }; 
 
 #define IP_REPLY_ARG_NOSRCCHECK 1
diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 260f83f16bc..25b4500f28c 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -131,7 +131,7 @@ extern int			rt6_route_rcv(struct net_device *dev,
 					      const struct in6_addr *gwaddr);
 
 extern void ip6_update_pmtu(struct sk_buff *skb, struct net *net, __be32 mtu,
-			    int oif, u32 mark);
+			    int oif, u32 mark, kuid_t uid);
 extern void ip6_sk_update_pmtu(struct sk_buff *skb, struct sock *sk,
 			       __be32 mtu);
 extern void ip6_redirect(struct sk_buff *skb, struct net *net, int oif, u32 mark);
diff --git a/include/net/route.h b/include/net/route.h
index 2ea40c1b5e0..b5b44875543 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -142,7 +142,7 @@ static inline struct rtable *ip_route_output_ports(struct net *net, struct flowi
 	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);
@@ -253,7 +253,8 @@ static inline void ip_route_connect_init(struct flowi4 *fl4, __be32 dst, __be32
 		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,
diff --git a/include/uapi/linux/fib_rules.h b/include/uapi/linux/fib_rules.h
index 51da65b68b8..9dcdb6251cb 100644
--- a/include/uapi/linux/fib_rules.h
+++ b/include/uapi/linux/fib_rules.h
@@ -49,6 +49,8 @@ enum {
 	FRA_TABLE,	/* Extended table id */
 	FRA_FWMASK,	/* mask for netfilter mark */
 	FRA_OIFNAME,
+	FRA_UID_START,	/* UID range */
+	FRA_UID_END,
 	__FRA_MAX
 };
 
diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h
index 7a2144e1afa..07c1146c1f5 100644
--- a/include/uapi/linux/rtnetlink.h
+++ b/include/uapi/linux/rtnetlink.h
@@ -297,6 +297,7 @@ enum rtattr_type_t {
 	RTA_TABLE,
 	RTA_MARK,
 	RTA_MFC_STATS,
+	RTA_UID,
 	__RTA_MAX
 };