net: core: add UID to flows, rules, and routes

- Define a new FIB rule attributes, FRA_UID_RANGE, to describe a
  range of UIDs.
- Define a RTA_UID attribute for per-UID route lookups and dumps.
- Support passing these attributes to and from userspace via
  rtnetlink. The value INVALID_UID indicates no UID was
  specified.
- Add a UID field to the flow structures.

Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

8 files changed, 111 insertions, 3 deletions

diff --git a/include/net/fib_rules.h b/include/net/fib_rules.h
index 456e4a6006ab..8dbfdf728cd8 100644
--- a/include/net/fib_rules.h
+++ b/include/net/fib_rules.h
@@ -8,6 +8,11 @@
 #include <net/flow.h>
 #include <net/rtnetlink.h>
 
+struct fib_kuid_range {
+        kuid_t start;
+        kuid_t end;
+};
+
 struct fib_rule {
         struct list_head        list;
         int                     iifindex;
@@ -30,6 +35,7 @@ struct fib_rule {
         int                     suppress_prefixlen;
         char                    iifname[IFNAMSIZ];
         char                    oifname[IFNAMSIZ];
+        struct fib_kuid_range   uid_range;
         struct rcu_head         rcu;
 };
 
@@ -92,7 +98,8 @@ struct fib_rules_ops {
         [FRA_SUPPRESS_PREFIXLEN] = { .type = NLA_U32 }, \
         [FRA_SUPPRESS_IFGROUP] = { .type = NLA_U32 }, \
         [FRA_GOTO]      = { .type = NLA_U32 }, \
-        [FRA_L3MDEV]    = { .type = NLA_U8 }
+        [FRA_L3MDEV]    = { .type = NLA_U8 }, \
+        [FRA_UID_RANGE] = { .len = sizeof(struct fib_rule_uid_range) }
 
 static inline void fib_rule_get(struct fib_rule *rule)
 {
diff --git a/include/net/flow.h b/include/net/flow.h
index 035aa7716967..51373f3a5e31 100644
--- a/include/net/flow.h
+++ b/include/net/flow.h
@@ -11,6 +11,7 @@
 #include <linux/in6.h>
 #include <linux/atomic.h>
 #include <net/flow_dissector.h>
+#include <linux/uidgid.h>
 
 /*
  * ifindex generation is per-net namespace, and loopback is
@@ -37,6 +38,7 @@ struct flowi_common {
 #define FLOWI_FLAG_SKIP_NH_OIF          0x04
         __u32   flowic_secid;
         struct flowi_tunnel flowic_tun_key;
+        kuid_t  flowic_uid;
 };
 
 union flowi_uli {
@@ -74,6 +76,7 @@ struct flowi4 {
 #define flowi4_flags            __fl_common.flowic_flags
 #define flowi4_secid            __fl_common.flowic_secid
 #define flowi4_tun_key          __fl_common.flowic_tun_key
+#define flowi4_uid              __fl_common.flowic_uid
 
         /* (saddr,daddr) must be grouped, same order as in IP header */
         __be32                  saddr;
@@ -131,6 +134,7 @@ struct flowi6 {
 #define flowi6_flags            __fl_common.flowic_flags
 #define flowi6_secid            __fl_common.flowic_secid
 #define flowi6_tun_key          __fl_common.flowic_tun_key
+#define flowi6_uid              __fl_common.flowic_uid
         struct in6_addr         daddr;
         struct in6_addr         saddr;
         /* Note: flowi6_tos is encoded in flowlabel, too. */
@@ -176,6 +180,7 @@ struct flowi {
 #define flowi_flags     u.__fl_common.flowic_flags
 #define flowi_secid     u.__fl_common.flowic_secid
 #define flowi_tun_key   u.__fl_common.flowic_tun_key
+#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/uapi/linux/fib_rules.h b/include/uapi/linux/fib_rules.h
index 14404b3ebb89..bbf02a63a011 100644
--- a/include/uapi/linux/fib_rules.h
+++ b/include/uapi/linux/fib_rules.h
@@ -29,6 +29,11 @@ struct fib_rule_hdr {
         __u32           flags;
 };
 
+struct fib_rule_uid_range {
+        __u32           start;
+        __u32           end;
+};
+
 enum {
         FRA_UNSPEC,
         FRA_DST,        /* destination address */
@@ -51,6 +56,7 @@ enum {
         FRA_OIFNAME,
         FRA_PAD,
         FRA_L3MDEV,     /* iif or oif is l3mdev goto its table */
+        FRA_UID_RANGE,  /* UID range */
         __FRA_MAX
 };
 
diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h
index 5a78be518101..e14377f2ec27 100644
--- a/include/uapi/linux/rtnetlink.h
+++ b/include/uapi/linux/rtnetlink.h
@@ -318,6 +318,7 @@ enum rtattr_type_t {
         RTA_ENCAP,
         RTA_EXPIRES,
         RTA_PAD,
+        RTA_UID,
         __RTA_MAX
 };
 
diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index be4629c344a6..5de436a73be2 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -18,6 +18,11 @@
 #include <net/fib_rules.h>
 #include <net/ip_tunnels.h>
 
+static const struct fib_kuid_range fib_kuid_range_unset = {
+        KUIDT_INIT(0),
+        KUIDT_INIT(~0),
+};
+
 int fib_default_rule_add(struct fib_rules_ops *ops,
                          u32 pref, u32 table, u32 flags)
 {
@@ -33,6 +38,7 @@ int fib_default_rule_add(struct fib_rules_ops *ops,
         r->table = table;
         r->flags = flags;
         r->fr_net = ops->fro_net;
+        r->uid_range = fib_kuid_range_unset;
 
         r->suppress_prefixlen = -1;
         r->suppress_ifgroup = -1;
@@ -172,6 +178,34 @@ void fib_rules_unregister(struct fib_rules_ops *ops)
 }
 EXPORT_SYMBOL_GPL(fib_rules_unregister);
 
+static int uid_range_set(struct fib_kuid_range *range)
+{
+        return uid_valid(range->start) && uid_valid(range->end);
+}
+
+static struct fib_kuid_range nla_get_kuid_range(struct nlattr **tb)
+{
+        struct fib_rule_uid_range *in;
+        struct fib_kuid_range out;
+
+        in = (struct fib_rule_uid_range *)nla_data(tb[FRA_UID_RANGE]);
+
+        out.start = make_kuid(current_user_ns(), in->start);
+        out.end = make_kuid(current_user_ns(), in->end);
+
+        return out;
+}
+
+static int nla_put_uid_range(struct sk_buff *skb, struct fib_kuid_range *range)
+{
+        struct fib_rule_uid_range out = {
+                from_kuid_munged(current_user_ns(), range->start),
+                from_kuid_munged(current_user_ns(), range->end)
+        };
+
+        return nla_put(skb, FRA_UID_RANGE, sizeof(out), &out);
+}
+
 static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops,
                           struct flowi *fl, int flags,
                           struct fib_lookup_arg *arg)
@@ -193,6 +227,10 @@ static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops,
         if (rule->l3mdev && !l3mdev_fib_rule_match(rule->fr_net, fl, arg))
                 goto out;
 
+        if (uid_lt(fl->flowi_uid, rule->uid_range.start) ||
+            uid_gt(fl->flowi_uid, rule->uid_range.end))
+                goto out;
+
         ret = ops->match(rule, fl, flags);
 out:
         return (rule->flags & FIB_RULE_INVERT) ? !ret : ret;
@@ -429,6 +467,21 @@ int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr *nlh)
         if (rule->l3mdev && rule->table)
                 goto errout_free;
 
+        if (tb[FRA_UID_RANGE]) {
+                if (current_user_ns() != net->user_ns) {
+                        err = -EPERM;
+                        goto errout_free;
+                }
+
+                rule->uid_range = nla_get_kuid_range(tb);
+
+                if (!uid_range_set(&rule->uid_range) ||
+                    !uid_lte(rule->uid_range.start, rule->uid_range.end))
+                        goto errout_free;
+        } else {
+                rule->uid_range = fib_kuid_range_unset;
+        }
+
         if ((nlh->nlmsg_flags & NLM_F_EXCL) &&
             rule_exists(ops, frh, tb, rule)) {
                 err = -EEXIST;
@@ -497,6 +550,7 @@ int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr *nlh)
         struct fib_rules_ops *ops = NULL;
         struct fib_rule *rule, *tmp;
         struct nlattr *tb[FRA_MAX+1];
+        struct fib_kuid_range range;
         int err = -EINVAL;
 
         if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
@@ -516,6 +570,14 @@ int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr *nlh)
         if (err < 0)
                 goto errout;
 
+        if (tb[FRA_UID_RANGE]) {
+                range = nla_get_kuid_range(tb);
+                if (!uid_range_set(&range))
+                        goto errout;
+        } else {
+                range = fib_kuid_range_unset;
+        }
+
         list_for_each_entry(rule, &ops->rules_list, list) {
                 if (frh->action && (frh->action != rule->action))
                         continue;
@@ -552,6 +614,11 @@ int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr *nlh)
                     (rule->l3mdev != nla_get_u8(tb[FRA_L3MDEV])))
                         continue;
 
+                if (uid_range_set(&range) &&
+                    (!uid_eq(rule->uid_range.start, range.start) ||
+                     !uid_eq(rule->uid_range.end, range.end)))
+                        continue;
+
                 if (!ops->compare(rule, frh, tb))
                         continue;
 
@@ -619,7 +686,8 @@ static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
                          + nla_total_size(4) /* FRA_SUPPRESS_IFGROUP */
                          + nla_total_size(4) /* FRA_FWMARK */
                          + nla_total_size(4) /* FRA_FWMASK */
-                         + nla_total_size_64bit(8); /* FRA_TUN_ID */
+                         + nla_total_size_64bit(8) /* FRA_TUN_ID */
+                         + nla_total_size(sizeof(struct fib_kuid_range));
 
         if (ops->nlmsg_payload)
                 payload += ops->nlmsg_payload(rule);
@@ -679,7 +747,9 @@ static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
             (rule->tun_id &&
              nla_put_be64(skb, FRA_TUN_ID, rule->tun_id, FRA_PAD)) ||
             (rule->l3mdev &&
-             nla_put_u8(skb, FRA_L3MDEV, rule->l3mdev)))
+             nla_put_u8(skb, FRA_L3MDEV, rule->l3mdev)) ||
+            (uid_range_set(&rule->uid_range) &&
+             nla_put_uid_range(skb, &rule->uid_range)))
                 goto nla_put_failure;
 
         if (rule->suppress_ifgroup != -1) {
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index c3b80478226e..d93eea8e2409 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -610,6 +610,7 @@ const struct nla_policy rtm_ipv4_policy[RTA_MAX + 1] = {
         [RTA_FLOW]              = { .type = NLA_U32 },
         [RTA_ENCAP_TYPE]        = { .type = NLA_U16 },
         [RTA_ENCAP]             = { .type = NLA_NESTED },
+        [RTA_UID]               = { .type = NLA_U32 },
 };
 
 static int rtm_to_fib_config(struct net *net, struct sk_buff *skb,
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 4392db83d540..92e59a638d3b 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2504,6 +2504,11 @@ static int rt_fill_info(struct net *net,  __be32 dst, __be32 src, u32 table_id,
             nla_put_u32(skb, RTA_MARK, fl4->flowi4_mark))
                 goto nla_put_failure;
 
+        if (!uid_eq(fl4->flowi4_uid, INVALID_UID) &&
+            nla_put_u32(skb, RTA_UID,
+                        from_kuid_munged(current_user_ns(), fl4->flowi4_uid)))
+                goto nla_put_failure;
+
         error = rt->dst.error;
 
         if (rt_is_input_route(rt)) {
@@ -2556,6 +2561,7 @@ static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh)
         int mark;
         struct sk_buff *skb;
         u32 table_id = RT_TABLE_MAIN;
+        kuid_t uid;
 
         err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_ipv4_policy);
         if (err < 0)
@@ -2583,6 +2589,10 @@ static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh)
         dst = tb[RTA_DST] ? nla_get_in_addr(tb[RTA_DST]) : 0;
         iif = tb[RTA_IIF] ? nla_get_u32(tb[RTA_IIF]) : 0;
         mark = tb[RTA_MARK] ? nla_get_u32(tb[RTA_MARK]) : 0;
+        if (tb[RTA_UID])
+                uid = make_kuid(current_user_ns(), nla_get_u32(tb[RTA_UID]));
+        else
+                uid = (iif ? INVALID_UID : current_uid());
 
         memset(&fl4, 0, sizeof(fl4));
         fl4.daddr = dst;
@@ -2590,6 +2600,7 @@ static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh)
         fl4.flowi4_tos = rtm->rtm_tos;
         fl4.flowi4_oif = tb[RTA_OIF] ? nla_get_u32(tb[RTA_OIF]) : 0;
         fl4.flowi4_mark = mark;
+        fl4.flowi4_uid = uid;
 
         if (iif) {
                 struct net_device *dev;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 947ed1ded026..fdb9c87137bd 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2797,6 +2797,7 @@ static const struct nla_policy rtm_ipv6_policy[RTA_MAX+1] = {
         [RTA_ENCAP_TYPE]        = { .type = NLA_U16 },
         [RTA_ENCAP]             = { .type = NLA_NESTED },
         [RTA_EXPIRES]           = { .type = NLA_U32 },
+        [RTA_UID]               = { .type = NLA_U32 },
 };
 
 static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh,
@@ -3371,6 +3372,12 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh)
         if (tb[RTA_MARK])
                 fl6.flowi6_mark = nla_get_u32(tb[RTA_MARK]);
 
+        if (tb[RTA_UID])
+                fl6.flowi6_uid = make_kuid(current_user_ns(),
+                                           nla_get_u32(tb[RTA_UID]));
+        else
+                fl6.flowi6_uid = iif ? INVALID_UID : current_uid();
+
         if (iif) {
                 struct net_device *dev;
                 int flags = 0;