Commit a68886a6 authored by David Ahern's avatar David Ahern Committed by David S. Miller

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: default avatarDavid Ahern <dsahern@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5bcaa41b
...@@ -174,7 +174,7 @@ struct fib6_info { ...@@ -174,7 +174,7 @@ struct fib6_info {
struct rt6_info { struct rt6_info {
struct dst_entry dst; struct dst_entry dst;
struct fib6_info *from; struct fib6_info __rcu *from;
struct rt6key rt6i_dst; struct rt6key rt6i_dst;
struct rt6key rt6i_src; struct rt6key rt6i_src;
...@@ -248,13 +248,15 @@ static inline bool fib6_get_cookie_safe(const struct fib6_info *f6i, ...@@ -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) static inline u32 rt6_get_cookie(const struct rt6_info *rt)
{ {
struct fib6_info *from;
u32 cookie = 0; u32 cookie = 0;
rcu_read_lock(); rcu_read_lock();
if (rt->rt6i_flags & RTF_PCPU || from = rcu_dereference(rt->from);
(unlikely(!list_empty(&rt->rt6i_uncached)) && rt->from)) if (from && (rt->rt6i_flags & RTF_PCPU ||
fib6_get_cookie_safe(rt->from, &cookie); unlikely(!list_empty(&rt->rt6i_uncached))))
fib6_get_cookie_safe(from, &cookie);
rcu_read_unlock(); rcu_read_unlock();
......
...@@ -875,8 +875,12 @@ static void fib6_drop_pcpu_from(struct fib6_info *f6i, ...@@ -875,8 +875,12 @@ static void fib6_drop_pcpu_from(struct fib6_info *f6i,
ppcpu_rt = per_cpu_ptr(f6i->rt6i_pcpu, cpu); ppcpu_rt = per_cpu_ptr(f6i->rt6i_pcpu, cpu);
pcpu_rt = *ppcpu_rt; pcpu_rt = *ppcpu_rt;
if (pcpu_rt) { if (pcpu_rt) {
fib6_info_release(pcpu_rt->from); struct fib6_info *from;
pcpu_rt->from = NULL;
from = rcu_dereference_protected(pcpu_rt->from,
lockdep_is_held(&table->tb6_lock));
rcu_assign_pointer(pcpu_rt->from, NULL);
fib6_info_release(from);
} }
} }
} }
......
...@@ -962,16 +962,21 @@ static int ip6_dst_lookup_tail(struct net *net, const struct sock *sk, ...@@ -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. * that's why we try it again later.
*/ */
if (ipv6_addr_any(&fl6->saddr) && (!*dst || !(*dst)->error)) { if (ipv6_addr_any(&fl6->saddr) && (!*dst || !(*dst)->error)) {
struct fib6_info *from;
struct rt6_info *rt; struct rt6_info *rt;
bool had_dst = *dst != NULL; bool had_dst = *dst != NULL;
if (!had_dst) if (!had_dst)
*dst = ip6_route_output(net, sk, fl6); *dst = ip6_route_output(net, sk, fl6);
rt = (*dst)->error ? NULL : (struct rt6_info *)*dst; 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, sk ? inet6_sk(sk)->srcprefs : 0,
&fl6->saddr); &fl6->saddr);
rcu_read_unlock();
if (err) if (err)
goto out_err_release; goto out_err_release;
......
...@@ -359,7 +359,7 @@ EXPORT_SYMBOL(ip6_dst_alloc); ...@@ -359,7 +359,7 @@ EXPORT_SYMBOL(ip6_dst_alloc);
static void ip6_dst_destroy(struct dst_entry *dst) static void ip6_dst_destroy(struct dst_entry *dst)
{ {
struct rt6_info *rt = (struct rt6_info *)dst; struct rt6_info *rt = (struct rt6_info *)dst;
struct fib6_info *from = rt->from; struct fib6_info *from;
struct inet6_dev *idev; struct inet6_dev *idev;
dst_destroy_metrics_generic(dst); dst_destroy_metrics_generic(dst);
...@@ -371,8 +371,11 @@ static void ip6_dst_destroy(struct dst_entry *dst) ...@@ -371,8 +371,11 @@ static void ip6_dst_destroy(struct dst_entry *dst)
in6_dev_put(idev); 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); fib6_info_release(from);
rcu_read_unlock();
} }
static void ip6_dst_ifdown(struct dst_entry *dst, struct net_device *dev, 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) ...@@ -402,12 +405,16 @@ static bool __rt6_check_expired(const struct rt6_info *rt)
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 (rt->rt6i_flags & RTF_EXPIRES) {
if (time_after(jiffies, rt->dst.expires)) if (time_after(jiffies, rt->dst.expires))
return true; return true;
} else if (rt->from) { } else if (from) {
return rt->dst.obsolete != DST_OBSOLETE_FORCE_CHK || return rt->dst.obsolete != DST_OBSOLETE_FORCE_CHK ||
fib6_check_expired(rt->from); fib6_check_expired(from);
} }
return false; return false;
} }
...@@ -963,7 +970,7 @@ static void rt6_set_from(struct rt6_info *rt, struct fib6_info *from) ...@@ -963,7 +970,7 @@ static void rt6_set_from(struct rt6_info *rt, struct fib6_info *from)
{ {
rt->rt6i_flags &= ~RTF_EXPIRES; rt->rt6i_flags &= ~RTF_EXPIRES;
fib6_info_hold(from); fib6_info_hold(from);
rt->from = from; rcu_assign_pointer(rt->from, from);
dst_init_metrics(&rt->dst, from->fib6_metrics->metrics, true); dst_init_metrics(&rt->dst, from->fib6_metrics->metrics, true);
if (from->fib6_metrics != &dst_default_metrics) { if (from->fib6_metrics != &dst_default_metrics) {
rt->dst._metrics |= DST_METRICS_REFCOUNTED; rt->dst._metrics |= DST_METRICS_REFCOUNTED;
...@@ -2133,11 +2140,13 @@ static bool fib6_check(struct fib6_info *f6i, u32 cookie) ...@@ -2133,11 +2140,13 @@ static bool fib6_check(struct fib6_info *f6i, u32 cookie)
return true; 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; 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) rt_cookie != cookie)
return NULL; return NULL;
...@@ -2147,11 +2156,13 @@ static struct dst_entry *rt6_check(struct rt6_info *rt, u32 cookie) ...@@ -2147,11 +2156,13 @@ static struct dst_entry *rt6_check(struct rt6_info *rt, u32 cookie)
return &rt->dst; 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) && if (!__rt6_check_expired(rt) &&
rt->dst.obsolete == DST_OBSOLETE_FORCE_CHK && rt->dst.obsolete == DST_OBSOLETE_FORCE_CHK &&
fib6_check(rt->from, cookie)) fib6_check(from, cookie))
return &rt->dst; return &rt->dst;
else else
return NULL; return NULL;
...@@ -2160,6 +2171,7 @@ static struct dst_entry *rt6_dst_from_check(struct rt6_info *rt, u32 cookie) ...@@ -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) static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie)
{ {
struct dst_entry *dst_ret; struct dst_entry *dst_ret;
struct fib6_info *from;
struct rt6_info *rt; struct rt6_info *rt;
rt = container_of(dst, struct rt6_info, dst); 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) ...@@ -2171,11 +2183,13 @@ static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie)
* into this function always. * into this function always.
*/ */
if (rt->rt6i_flags & RTF_PCPU || from = rcu_dereference(rt->from);
(unlikely(!list_empty(&rt->rt6i_uncached)) && rt->from))
dst_ret = rt6_dst_from_check(rt, cookie); if (from && (rt->rt6i_flags & RTF_PCPU ||
unlikely(!list_empty(&rt->rt6i_uncached))))
dst_ret = rt6_dst_from_check(rt, from, cookie);
else else
dst_ret = rt6_check(rt, cookie); dst_ret = rt6_check(rt, from, cookie);
rcu_read_unlock(); rcu_read_unlock();
...@@ -2211,13 +2225,17 @@ static void ip6_link_failure(struct sk_buff *skb) ...@@ -2211,13 +2225,17 @@ static void ip6_link_failure(struct sk_buff *skb)
if (rt->rt6i_flags & RTF_CACHE) { if (rt->rt6i_flags & RTF_CACHE) {
if (dst_hold_safe(&rt->dst)) if (dst_hold_safe(&rt->dst))
rt6_remove_exception_rt(rt); rt6_remove_exception_rt(rt);
} else if (rt->from) { } else {
struct fib6_info *from;
struct fib6_node *fn; struct fib6_node *fn;
rcu_read_lock(); rcu_read_lock();
fn = rcu_dereference(rt->from->fib6_node); from = rcu_dereference(rt->from);
if (from) {
fn = rcu_dereference(from->fib6_node);
if (fn && (rt->rt6i_flags & RTF_DEFAULT)) if (fn && (rt->rt6i_flags & RTF_DEFAULT))
fn->fn_sernum = -1; fn->fn_sernum = -1;
}
rcu_read_unlock(); rcu_read_unlock();
} }
} }
...@@ -2225,8 +2243,15 @@ static void ip6_link_failure(struct sk_buff *skb) ...@@ -2225,8 +2243,15 @@ static void ip6_link_failure(struct sk_buff *skb)
static void rt6_update_expires(struct rt6_info *rt0, int timeout) static void rt6_update_expires(struct rt6_info *rt0, int timeout)
{ {
if (!(rt0->rt6i_flags & RTF_EXPIRES) && rt0->from) if (!(rt0->rt6i_flags & RTF_EXPIRES)) {
rt0->dst.expires = rt0->from->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); dst_set_expires(&rt0->dst, timeout);
rt0->rt6i_flags |= RTF_EXPIRES; rt0->rt6i_flags |= RTF_EXPIRES;
...@@ -2243,8 +2268,14 @@ static void rt6_do_update_pmtu(struct rt6_info *rt, u32 mtu) ...@@ -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) 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) && 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, 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, ...@@ -2280,16 +2311,18 @@ static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,
if (rt6->rt6i_flags & RTF_CACHE) if (rt6->rt6i_flags & RTF_CACHE)
rt6_update_exception_stamp_rt(rt6); rt6_update_exception_stamp_rt(rt6);
} else if (daddr) { } else if (daddr) {
struct fib6_info *from;
struct rt6_info *nrt6; struct rt6_info *nrt6;
rcu_read_lock(); rcu_read_lock();
nrt6 = ip6_rt_cache_alloc(rt6->from, daddr, saddr); from = rcu_dereference(rt6->from);
rcu_read_unlock(); nrt6 = ip6_rt_cache_alloc(from, daddr, saddr);
if (nrt6) { if (nrt6) {
rt6_do_update_pmtu(nrt6, mtu); rt6_do_update_pmtu(nrt6, mtu);
if (rt6_insert_exception(nrt6, rt6->from)) if (rt6_insert_exception(nrt6, from))
dst_release_immediate(&nrt6->dst); 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 ...@@ -3222,6 +3255,7 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu
struct ndisc_options ndopts; struct ndisc_options ndopts;
struct inet6_dev *in6_dev; struct inet6_dev *in6_dev;
struct neighbour *neigh; struct neighbour *neigh;
struct fib6_info *from;
struct rd_msg *msg; struct rd_msg *msg;
int optlen, on_link; int optlen, on_link;
u8 *lladdr; u8 *lladdr;
...@@ -3304,7 +3338,8 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu ...@@ -3304,7 +3338,8 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu
NDISC_REDIRECT, &ndopts); NDISC_REDIRECT, &ndopts);
rcu_read_lock(); 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(); rcu_read_unlock();
if (!nrt) if (!nrt)
goto out; goto out;
...@@ -4687,6 +4722,7 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh, ...@@ -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 net *net = sock_net(in_skb->sk);
struct nlattr *tb[RTA_MAX+1]; struct nlattr *tb[RTA_MAX+1];
int err, iif = 0, oif = 0; int err, iif = 0, oif = 0;
struct fib6_info *from;
struct dst_entry *dst; struct dst_entry *dst;
struct rt6_info *rt; struct rt6_info *rt;
struct sk_buff *skb; struct sk_buff *skb;
...@@ -4783,15 +4819,21 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh, ...@@ -4783,15 +4819,21 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
} }
skb_dst_set(skb, &rt->dst); skb_dst_set(skb, &rt->dst);
rcu_read_lock();
from = rcu_dereference(rt->from);
if (fibmatch) 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, RTM_NEWROUTE, NETLINK_CB(in_skb).portid,
nlh->nlmsg_seq, 0); nlh->nlmsg_seq, 0);
else else
err = rt6_fill_node(net, skb, rt->from, dst, err = rt6_fill_node(net, skb, from, dst, &fl6.daddr,
&fl6.daddr, &fl6.saddr, iif, RTM_NEWROUTE, &fl6.saddr, iif, RTM_NEWROUTE,
NETLINK_CB(in_skb).portid, nlh->nlmsg_seq, NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
0); 0);
rcu_read_unlock();
if (err < 0) { if (err < 0) {
kfree_skb(skb); kfree_skb(skb);
goto errout; goto errout;
......
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