kernel_optimize_test/include/net/fib_rules.h
msizanoen1 209d35ee34 ipv6: fix memory leak in fib6_rule_suppress
commit cdef485217d30382f3bf6448c54b4401648fe3f1 upstream.

The kernel leaks memory when a `fib` rule is present in IPv6 nftables
firewall rules and a suppress_prefix rule is present in the IPv6 routing
rules (used by certain tools such as wg-quick). In such scenarios, every
incoming packet will leak an allocation in `ip6_dst_cache` slab cache.

After some hours of `bpftrace`-ing and source code reading, I tracked
down the issue to ca7a03c417 ("ipv6: do not free rt if
FIB_LOOKUP_NOREF is set on suppress rule").

The problem with that change is that the generic `args->flags` always have
`FIB_LOOKUP_NOREF` set[1][2] but the IPv6-specific flag
`RT6_LOOKUP_F_DST_NOREF` might not be, leading to `fib6_rule_suppress` not
decreasing the refcount when needed.

How to reproduce:
 - Add the following nftables rule to a prerouting chain:
     meta nfproto ipv6 fib saddr . mark . iif oif missing drop
   This can be done with:
     sudo nft create table inet test
     sudo nft create chain inet test test_chain '{ type filter hook prerouting priority filter + 10; policy accept; }'
     sudo nft add rule inet test test_chain meta nfproto ipv6 fib saddr . mark . iif oif missing drop
 - Run:
     sudo ip -6 rule add table main suppress_prefixlength 0
 - Watch `sudo slabtop -o | grep ip6_dst_cache` to see memory usage increase
   with every incoming ipv6 packet.

This patch exposes the protocol-specific flags to the protocol
specific `suppress` function, and check the protocol-specific `flags`
argument for RT6_LOOKUP_F_DST_NOREF instead of the generic
FIB_LOOKUP_NOREF when decreasing the refcount, like this.

[1]: ca7a03c417/net/ipv6/fib6_rules.c (L71)
[2]: ca7a03c417/net/ipv6/fib6_rules.c (L99)

Link: https://bugzilla.kernel.org/show_bug.cgi?id=215105
Fixes: ca7a03c417 ("ipv6: do not free rt if FIB_LOOKUP_NOREF is set on suppress rule")
Cc: stable@vger.kernel.org
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-12-08 09:03:21 +01:00

227 lines
6.3 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __NET_FIB_RULES_H
#define __NET_FIB_RULES_H
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#include <linux/fib_rules.h>
#include <linux/refcount.h>
#include <net/flow.h>
#include <net/rtnetlink.h>
#include <net/fib_notifier.h>
#include <linux/indirect_call_wrapper.h>
struct fib_kuid_range {
kuid_t start;
kuid_t end;
};
struct fib_rule {
struct list_head list;
int iifindex;
int oifindex;
u32 mark;
u32 mark_mask;
u32 flags;
u32 table;
u8 action;
u8 l3mdev;
u8 proto;
u8 ip_proto;
u32 target;
__be64 tun_id;
struct fib_rule __rcu *ctarget;
struct net *fr_net;
refcount_t refcnt;
u32 pref;
int suppress_ifgroup;
int suppress_prefixlen;
char iifname[IFNAMSIZ];
char oifname[IFNAMSIZ];
struct fib_kuid_range uid_range;
struct fib_rule_port_range sport_range;
struct fib_rule_port_range dport_range;
struct rcu_head rcu;
};
struct fib_lookup_arg {
void *lookup_ptr;
const void *lookup_data;
void *result;
struct fib_rule *rule;
u32 table;
int flags;
#define FIB_LOOKUP_NOREF 1
#define FIB_LOOKUP_IGNORE_LINKSTATE 2
};
struct fib_rules_ops {
int family;
struct list_head list;
int rule_size;
int addr_size;
int unresolved_rules;
int nr_goto_rules;
unsigned int fib_rules_seq;
int (*action)(struct fib_rule *,
struct flowi *, int,
struct fib_lookup_arg *);
bool (*suppress)(struct fib_rule *, int,
struct fib_lookup_arg *);
int (*match)(struct fib_rule *,
struct flowi *, int);
int (*configure)(struct fib_rule *,
struct sk_buff *,
struct fib_rule_hdr *,
struct nlattr **,
struct netlink_ext_ack *);
int (*delete)(struct fib_rule *);
int (*compare)(struct fib_rule *,
struct fib_rule_hdr *,
struct nlattr **);
int (*fill)(struct fib_rule *, struct sk_buff *,
struct fib_rule_hdr *);
size_t (*nlmsg_payload)(struct fib_rule *);
/* Called after modifications to the rules set, must flush
* the route cache if one exists. */
void (*flush_cache)(struct fib_rules_ops *ops);
int nlgroup;
const struct nla_policy *policy;
struct list_head rules_list;
struct module *owner;
struct net *fro_net;
struct rcu_head rcu;
};
struct fib_rule_notifier_info {
struct fib_notifier_info info; /* must be first */
struct fib_rule *rule;
};
#define FRA_GENERIC_POLICY \
[FRA_UNSPEC] = { .strict_start_type = FRA_DPORT_RANGE + 1 }, \
[FRA_IIFNAME] = { .type = NLA_STRING, .len = IFNAMSIZ - 1 }, \
[FRA_OIFNAME] = { .type = NLA_STRING, .len = IFNAMSIZ - 1 }, \
[FRA_PRIORITY] = { .type = NLA_U32 }, \
[FRA_FWMARK] = { .type = NLA_U32 }, \
[FRA_TUN_ID] = { .type = NLA_U64 }, \
[FRA_FWMASK] = { .type = NLA_U32 }, \
[FRA_TABLE] = { .type = NLA_U32 }, \
[FRA_SUPPRESS_PREFIXLEN] = { .type = NLA_U32 }, \
[FRA_SUPPRESS_IFGROUP] = { .type = NLA_U32 }, \
[FRA_GOTO] = { .type = NLA_U32 }, \
[FRA_L3MDEV] = { .type = NLA_U8 }, \
[FRA_UID_RANGE] = { .len = sizeof(struct fib_rule_uid_range) }, \
[FRA_PROTOCOL] = { .type = NLA_U8 }, \
[FRA_IP_PROTO] = { .type = NLA_U8 }, \
[FRA_SPORT_RANGE] = { .len = sizeof(struct fib_rule_port_range) }, \
[FRA_DPORT_RANGE] = { .len = sizeof(struct fib_rule_port_range) }
static inline void fib_rule_get(struct fib_rule *rule)
{
refcount_inc(&rule->refcnt);
}
static inline void fib_rule_put(struct fib_rule *rule)
{
if (refcount_dec_and_test(&rule->refcnt))
kfree_rcu(rule, rcu);
}
#ifdef CONFIG_NET_L3_MASTER_DEV
static inline u32 fib_rule_get_table(struct fib_rule *rule,
struct fib_lookup_arg *arg)
{
return rule->l3mdev ? arg->table : rule->table;
}
#else
static inline u32 fib_rule_get_table(struct fib_rule *rule,
struct fib_lookup_arg *arg)
{
return rule->table;
}
#endif
static inline u32 frh_get_table(struct fib_rule_hdr *frh, struct nlattr **nla)
{
if (nla[FRA_TABLE])
return nla_get_u32(nla[FRA_TABLE]);
return frh->table;
}
static inline bool fib_rule_port_range_set(const struct fib_rule_port_range *range)
{
return range->start != 0 && range->end != 0;
}
static inline bool fib_rule_port_inrange(const struct fib_rule_port_range *a,
__be16 port)
{
return ntohs(port) >= a->start &&
ntohs(port) <= a->end;
}
static inline bool fib_rule_port_range_valid(const struct fib_rule_port_range *a)
{
return a->start != 0 && a->end != 0 && a->end < 0xffff &&
a->start <= a->end;
}
static inline bool fib_rule_port_range_compare(struct fib_rule_port_range *a,
struct fib_rule_port_range *b)
{
return a->start == b->start &&
a->end == b->end;
}
static inline bool fib_rule_requires_fldissect(struct fib_rule *rule)
{
return rule->iifindex != LOOPBACK_IFINDEX && (rule->ip_proto ||
fib_rule_port_range_set(&rule->sport_range) ||
fib_rule_port_range_set(&rule->dport_range));
}
struct fib_rules_ops *fib_rules_register(const struct fib_rules_ops *,
struct net *);
void fib_rules_unregister(struct fib_rules_ops *);
int fib_rules_lookup(struct fib_rules_ops *, struct flowi *, int flags,
struct fib_lookup_arg *);
int fib_default_rule_add(struct fib_rules_ops *, u32 pref, u32 table,
u32 flags);
bool fib_rule_matchall(const struct fib_rule *rule);
int fib_rules_dump(struct net *net, struct notifier_block *nb, int family,
struct netlink_ext_ack *extack);
unsigned int fib_rules_seq_read(struct net *net, int family);
int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr *nlh,
struct netlink_ext_ack *extack);
int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr *nlh,
struct netlink_ext_ack *extack);
INDIRECT_CALLABLE_DECLARE(int fib6_rule_match(struct fib_rule *rule,
struct flowi *fl, int flags));
INDIRECT_CALLABLE_DECLARE(int fib4_rule_match(struct fib_rule *rule,
struct flowi *fl, int flags));
INDIRECT_CALLABLE_DECLARE(int fib6_rule_action(struct fib_rule *rule,
struct flowi *flp, int flags,
struct fib_lookup_arg *arg));
INDIRECT_CALLABLE_DECLARE(int fib4_rule_action(struct fib_rule *rule,
struct flowi *flp, int flags,
struct fib_lookup_arg *arg));
INDIRECT_CALLABLE_DECLARE(bool fib6_rule_suppress(struct fib_rule *rule,
int flags,
struct fib_lookup_arg *arg));
INDIRECT_CALLABLE_DECLARE(bool fib4_rule_suppress(struct fib_rule *rule,
int flags,
struct fib_lookup_arg *arg));
#endif