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Message-Id: <20180420223803.15743-7-dsahern@gmail.com>
Date: Fri, 20 Apr 2018 15:38:02 -0700
From: David Ahern <dsahern@...il.com>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net, idosch@...sch.org, roopa@...ulusnetworks.com,
eric.dumazet@...il.com, weiwan@...gle.com, kafai@...com,
yoshfuji@...ux-ipv6.org, David Ahern <dsahern@...il.com>
Subject: [PATCH net-next 6/7] net/ipv6: Make from in rt6_info rcu protected
When a dst entry is created from a fib entry, the 'from' in rt6_info
is set to the fib entry. The 'from' reference is used most notably for
cookie checking - making sure stale dst entries are updated if the
fib entry is changed.
When a fib entry is deleted, the pcpu routes on it are walked releasing
the fib6_info reference. This is needed for the fib6_info cleanup to
happen and to make sure all device references are released in a timely
manner.
There is a race window when a FIB entry is deleted and the 'from' on the
pcpu route is dropped and the pcpu route hits a cookie check. Handle
this race using rcu on from.
Signed-off-by: David Ahern <dsahern@...il.com>
---
include/net/ip6_fib.h | 10 +++---
net/ipv6/ip6_fib.c | 8 +++--
net/ipv6/ip6_output.c | 9 +++--
net/ipv6/route.c | 96 ++++++++++++++++++++++++++++++++++++---------------
4 files changed, 88 insertions(+), 35 deletions(-)
diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index dc3505fb62b3..1af450d4e923 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -174,7 +174,7 @@ struct fib6_info {
struct rt6_info {
struct dst_entry dst;
- struct fib6_info *from;
+ struct fib6_info __rcu *from;
struct rt6key rt6i_dst;
struct rt6key rt6i_src;
@@ -248,13 +248,15 @@ static inline bool fib6_get_cookie_safe(const struct fib6_info *f6i,
static inline u32 rt6_get_cookie(const struct rt6_info *rt)
{
+ struct fib6_info *from;
u32 cookie = 0;
rcu_read_lock();
- if (rt->rt6i_flags & RTF_PCPU ||
- (unlikely(!list_empty(&rt->rt6i_uncached)) && rt->from))
- fib6_get_cookie_safe(rt->from, &cookie);
+ from = rcu_dereference(rt->from);
+ if (from && (rt->rt6i_flags & RTF_PCPU ||
+ unlikely(!list_empty(&rt->rt6i_uncached))))
+ fib6_get_cookie_safe(from, &cookie);
rcu_read_unlock();
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 64ca02b7745f..6421c893466e 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -875,8 +875,12 @@ static void fib6_drop_pcpu_from(struct fib6_info *f6i,
ppcpu_rt = per_cpu_ptr(f6i->rt6i_pcpu, cpu);
pcpu_rt = *ppcpu_rt;
if (pcpu_rt) {
- fib6_info_release(pcpu_rt->from);
- pcpu_rt->from = NULL;
+ struct fib6_info *from;
+
+ from = rcu_dereference_protected(pcpu_rt->from,
+ lockdep_is_held(&table->tb6_lock));
+ rcu_assign_pointer(pcpu_rt->from, NULL);
+ fib6_info_release(from);
}
}
}
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 3db47986ef38..6a477d54f8c7 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -962,16 +962,21 @@ static int ip6_dst_lookup_tail(struct net *net, const struct sock *sk,
* that's why we try it again later.
*/
if (ipv6_addr_any(&fl6->saddr) && (!*dst || !(*dst)->error)) {
+ struct fib6_info *from;
struct rt6_info *rt;
bool had_dst = *dst != NULL;
if (!had_dst)
*dst = ip6_route_output(net, sk, fl6);
rt = (*dst)->error ? NULL : (struct rt6_info *)*dst;
- err = ip6_route_get_saddr(net, rt ? rt->from : NULL,
- &fl6->daddr,
+
+ rcu_read_lock();
+ from = rt ? rcu_dereference(rt->from) : NULL;
+ err = ip6_route_get_saddr(net, from, &fl6->daddr,
sk ? inet6_sk(sk)->srcprefs : 0,
&fl6->saddr);
+ rcu_read_unlock();
+
if (err)
goto out_err_release;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 810a37ac043b..004d00fe2fe5 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -359,7 +359,7 @@ EXPORT_SYMBOL(ip6_dst_alloc);
static void ip6_dst_destroy(struct dst_entry *dst)
{
struct rt6_info *rt = (struct rt6_info *)dst;
- struct fib6_info *from = rt->from;
+ struct fib6_info *from;
struct inet6_dev *idev;
dst_destroy_metrics_generic(dst);
@@ -371,8 +371,11 @@ static void ip6_dst_destroy(struct dst_entry *dst)
in6_dev_put(idev);
}
- rt->from = NULL;
+ rcu_read_lock();
+ from = rcu_dereference(rt->from);
+ rcu_assign_pointer(rt->from, NULL);
fib6_info_release(from);
+ rcu_read_unlock();
}
static void ip6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
@@ -402,12 +405,16 @@ static bool __rt6_check_expired(const struct rt6_info *rt)
static bool rt6_check_expired(const struct rt6_info *rt)
{
+ struct fib6_info *from;
+
+ from = rcu_dereference(rt->from);
+
if (rt->rt6i_flags & RTF_EXPIRES) {
if (time_after(jiffies, rt->dst.expires))
return true;
- } else if (rt->from) {
+ } else if (from) {
return rt->dst.obsolete != DST_OBSOLETE_FORCE_CHK ||
- fib6_check_expired(rt->from);
+ fib6_check_expired(from);
}
return false;
}
@@ -963,7 +970,7 @@ static void rt6_set_from(struct rt6_info *rt, struct fib6_info *from)
{
rt->rt6i_flags &= ~RTF_EXPIRES;
fib6_info_hold(from);
- rt->from = from;
+ rcu_assign_pointer(rt->from, from);
dst_init_metrics(&rt->dst, from->fib6_metrics->metrics, true);
if (from->fib6_metrics != &dst_default_metrics) {
rt->dst._metrics |= DST_METRICS_REFCOUNTED;
@@ -2133,11 +2140,13 @@ static bool fib6_check(struct fib6_info *f6i, u32 cookie)
return true;
}
-static struct dst_entry *rt6_check(struct rt6_info *rt, u32 cookie)
+static struct dst_entry *rt6_check(struct rt6_info *rt,
+ struct fib6_info *from,
+ u32 cookie)
{
u32 rt_cookie = 0;
- if ((rt->from && !fib6_get_cookie_safe(rt->from, &rt_cookie)) ||
+ if ((from && !fib6_get_cookie_safe(from, &rt_cookie)) ||
rt_cookie != cookie)
return NULL;
@@ -2147,11 +2156,13 @@ static struct dst_entry *rt6_check(struct rt6_info *rt, u32 cookie)
return &rt->dst;
}
-static struct dst_entry *rt6_dst_from_check(struct rt6_info *rt, u32 cookie)
+static struct dst_entry *rt6_dst_from_check(struct rt6_info *rt,
+ struct fib6_info *from,
+ u32 cookie)
{
if (!__rt6_check_expired(rt) &&
rt->dst.obsolete == DST_OBSOLETE_FORCE_CHK &&
- fib6_check(rt->from, cookie))
+ fib6_check(from, cookie))
return &rt->dst;
else
return NULL;
@@ -2160,6 +2171,7 @@ static struct dst_entry *rt6_dst_from_check(struct rt6_info *rt, u32 cookie)
static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie)
{
struct dst_entry *dst_ret;
+ struct fib6_info *from;
struct rt6_info *rt;
rt = container_of(dst, struct rt6_info, dst);
@@ -2171,11 +2183,13 @@ static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie)
* into this function always.
*/
- if (rt->rt6i_flags & RTF_PCPU ||
- (unlikely(!list_empty(&rt->rt6i_uncached)) && rt->from))
- dst_ret = rt6_dst_from_check(rt, cookie);
+ from = rcu_dereference(rt->from);
+
+ if (from && (rt->rt6i_flags & RTF_PCPU ||
+ unlikely(!list_empty(&rt->rt6i_uncached))))
+ dst_ret = rt6_dst_from_check(rt, from, cookie);
else
- dst_ret = rt6_check(rt, cookie);
+ dst_ret = rt6_check(rt, from, cookie);
rcu_read_unlock();
@@ -2211,13 +2225,17 @@ static void ip6_link_failure(struct sk_buff *skb)
if (rt->rt6i_flags & RTF_CACHE) {
if (dst_hold_safe(&rt->dst))
rt6_remove_exception_rt(rt);
- } else if (rt->from) {
+ } else {
+ struct fib6_info *from;
struct fib6_node *fn;
rcu_read_lock();
- fn = rcu_dereference(rt->from->fib6_node);
- if (fn && (rt->rt6i_flags & RTF_DEFAULT))
- fn->fn_sernum = -1;
+ from = rcu_dereference(rt->from);
+ if (from) {
+ fn = rcu_dereference(from->fib6_node);
+ if (fn && (rt->rt6i_flags & RTF_DEFAULT))
+ fn->fn_sernum = -1;
+ }
rcu_read_unlock();
}
}
@@ -2225,8 +2243,15 @@ static void ip6_link_failure(struct sk_buff *skb)
static void rt6_update_expires(struct rt6_info *rt0, int timeout)
{
- if (!(rt0->rt6i_flags & RTF_EXPIRES) && rt0->from)
- rt0->dst.expires = rt0->from->expires;
+ if (!(rt0->rt6i_flags & RTF_EXPIRES)) {
+ struct fib6_info *from;
+
+ rcu_read_lock();
+ from = rcu_dereference(rt0->from);
+ if (from)
+ rt0->dst.expires = from->expires;
+ rcu_read_unlock();
+ }
dst_set_expires(&rt0->dst, timeout);
rt0->rt6i_flags |= RTF_EXPIRES;
@@ -2243,8 +2268,14 @@ static void rt6_do_update_pmtu(struct rt6_info *rt, u32 mtu)
static bool rt6_cache_allowed_for_pmtu(const struct rt6_info *rt)
{
+ bool from_set;
+
+ rcu_read_lock();
+ from_set = !!rcu_dereference(rt->from);
+ rcu_read_unlock();
+
return !(rt->rt6i_flags & RTF_CACHE) &&
- (rt->rt6i_flags & RTF_PCPU || rt->from);
+ (rt->rt6i_flags & RTF_PCPU || from_set);
}
static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,
@@ -2280,16 +2311,18 @@ static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,
if (rt6->rt6i_flags & RTF_CACHE)
rt6_update_exception_stamp_rt(rt6);
} else if (daddr) {
+ struct fib6_info *from;
struct rt6_info *nrt6;
rcu_read_lock();
- nrt6 = ip6_rt_cache_alloc(rt6->from, daddr, saddr);
- rcu_read_unlock();
+ from = rcu_dereference(rt6->from);
+ nrt6 = ip6_rt_cache_alloc(from, daddr, saddr);
if (nrt6) {
rt6_do_update_pmtu(nrt6, mtu);
- if (rt6_insert_exception(nrt6, rt6->from))
+ if (rt6_insert_exception(nrt6, from))
dst_release_immediate(&nrt6->dst);
}
+ rcu_read_unlock();
}
}
@@ -3222,6 +3255,7 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu
struct ndisc_options ndopts;
struct inet6_dev *in6_dev;
struct neighbour *neigh;
+ struct fib6_info *from;
struct rd_msg *msg;
int optlen, on_link;
u8 *lladdr;
@@ -3304,7 +3338,8 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu
NDISC_REDIRECT, &ndopts);
rcu_read_lock();
- nrt = ip6_rt_cache_alloc(rt->from, &msg->dest, NULL);
+ from = rcu_dereference(rt->from);
+ nrt = ip6_rt_cache_alloc(from, &msg->dest, NULL);
rcu_read_unlock();
if (!nrt)
goto out;
@@ -4687,6 +4722,7 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
struct net *net = sock_net(in_skb->sk);
struct nlattr *tb[RTA_MAX+1];
int err, iif = 0, oif = 0;
+ struct fib6_info *from;
struct dst_entry *dst;
struct rt6_info *rt;
struct sk_buff *skb;
@@ -4783,15 +4819,21 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
}
skb_dst_set(skb, &rt->dst);
+
+ rcu_read_lock();
+ from = rcu_dereference(rt->from);
+
if (fibmatch)
- err = rt6_fill_node(net, skb, rt->from, NULL, NULL, NULL, iif,
+ err = rt6_fill_node(net, skb, from, NULL, NULL, NULL, iif,
RTM_NEWROUTE, NETLINK_CB(in_skb).portid,
nlh->nlmsg_seq, 0);
else
- err = rt6_fill_node(net, skb, rt->from, dst,
- &fl6.daddr, &fl6.saddr, iif, RTM_NEWROUTE,
+ err = rt6_fill_node(net, skb, from, dst, &fl6.daddr,
+ &fl6.saddr, iif, RTM_NEWROUTE,
NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
0);
+ rcu_read_unlock();
+
if (err < 0) {
kfree_skb(skb);
goto errout;
--
2.11.0
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