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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>
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lcolitti authored and davem330 committed Nov 3, 2016
1 parent 86741ec commit 622ec2c9d52405973c9f1ca5116eb1c393adfc7d
@@ -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)
{
@@ -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)
@@ -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
};

@@ -318,6 +318,7 @@ enum rtattr_type_t {
RTA_ENCAP,
RTA_EXPIRES,
RTA_PAD,
RTA_UID,
__RTA_MAX
};

@@ -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) {
@@ -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,
@@ -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)
@@ -2583,13 +2589,18 @@ 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;
fl4.saddr = src;
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;
@@ -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;

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