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Message-Id: <1437012853-7318-4-git-send-email-horms@verge.net.au>
Date: Thu, 16 Jul 2015 11:14:10 +0900
From: Simon Horman <horms@...ge.net.au>
To: Pablo Neira Ayuso <pablo@...filter.org>
Cc: lvs-devel@...r.kernel.org, netdev@...r.kernel.org,
netfilter-devel@...r.kernel.org,
Wensong Zhang <wensong@...ux-vs.org>,
Julian Anastasov <ja@....bg>, Simon Horman <horms@...ge.net.au>
Subject: [PATCH nf 3/6] ipvs: fix crash if scheduler is changed
From: Julian Anastasov <ja@....bg>
I overlooked the svc->sched_data usage from schedulers
when the services were converted to RCU in 3.10. Now
the rare ipvsadm -E command can change the scheduler
but due to the reverse order of ip_vs_bind_scheduler
and ip_vs_unbind_scheduler we provide new sched_data
to the old scheduler resulting in a crash.
To fix it without changing the scheduler methods we
have to use synchronize_rcu() only for the editing case.
It means all svc->scheduler readers should expect a
NULL value. To avoid breakage for the service listing
and ipvsadm -R we can use the "none" name to indicate
that scheduler is not assigned, a state when we drop
new connections.
Reported-by: Alexander Vasiliev <a.vasylev@...-group.com>
Fixes: ceec4c381681 ("ipvs: convert services to rcu")
Signed-off-by: Julian Anastasov <ja@....bg>
Signed-off-by: Simon Horman <horms@...ge.net.au>
---
net/netfilter/ipvs/ip_vs_core.c | 16 +++++++--
net/netfilter/ipvs/ip_vs_ctl.c | 78 +++++++++++++++++++++++++---------------
net/netfilter/ipvs/ip_vs_sched.c | 12 +++----
3 files changed, 69 insertions(+), 37 deletions(-)
diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
index 5d2b806a862e..38fbc194b9cb 100644
--- a/net/netfilter/ipvs/ip_vs_core.c
+++ b/net/netfilter/ipvs/ip_vs_core.c
@@ -319,7 +319,13 @@ ip_vs_sched_persist(struct ip_vs_service *svc,
* return *ignored=0 i.e. ICMP and NF_DROP
*/
sched = rcu_dereference(svc->scheduler);
- dest = sched->schedule(svc, skb, iph);
+ if (sched) {
+ /* read svc->sched_data after svc->scheduler */
+ smp_rmb();
+ dest = sched->schedule(svc, skb, iph);
+ } else {
+ dest = NULL;
+ }
if (!dest) {
IP_VS_DBG(1, "p-schedule: no dest found.\n");
kfree(param.pe_data);
@@ -467,7 +473,13 @@ ip_vs_schedule(struct ip_vs_service *svc, struct sk_buff *skb,
}
sched = rcu_dereference(svc->scheduler);
- dest = sched->schedule(svc, skb, iph);
+ if (sched) {
+ /* read svc->sched_data after svc->scheduler */
+ smp_rmb();
+ dest = sched->schedule(svc, skb, iph);
+ } else {
+ dest = NULL;
+ }
if (dest == NULL) {
IP_VS_DBG(1, "Schedule: no dest found.\n");
return NULL;
diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index 285eae3a1454..24c554201a76 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -842,15 +842,16 @@ __ip_vs_update_dest(struct ip_vs_service *svc, struct ip_vs_dest *dest,
__ip_vs_dst_cache_reset(dest);
spin_unlock_bh(&dest->dst_lock);
- sched = rcu_dereference_protected(svc->scheduler, 1);
if (add) {
ip_vs_start_estimator(svc->net, &dest->stats);
list_add_rcu(&dest->n_list, &svc->destinations);
svc->num_dests++;
- if (sched->add_dest)
+ sched = rcu_dereference_protected(svc->scheduler, 1);
+ if (sched && sched->add_dest)
sched->add_dest(svc, dest);
} else {
- if (sched->upd_dest)
+ sched = rcu_dereference_protected(svc->scheduler, 1);
+ if (sched && sched->upd_dest)
sched->upd_dest(svc, dest);
}
}
@@ -1084,7 +1085,7 @@ static void __ip_vs_unlink_dest(struct ip_vs_service *svc,
struct ip_vs_scheduler *sched;
sched = rcu_dereference_protected(svc->scheduler, 1);
- if (sched->del_dest)
+ if (sched && sched->del_dest)
sched->del_dest(svc, dest);
}
}
@@ -1175,11 +1176,14 @@ ip_vs_add_service(struct net *net, struct ip_vs_service_user_kern *u,
ip_vs_use_count_inc();
/* Lookup the scheduler by 'u->sched_name' */
- sched = ip_vs_scheduler_get(u->sched_name);
- if (sched == NULL) {
- pr_info("Scheduler module ip_vs_%s not found\n", u->sched_name);
- ret = -ENOENT;
- goto out_err;
+ if (strcmp(u->sched_name, "none")) {
+ sched = ip_vs_scheduler_get(u->sched_name);
+ if (!sched) {
+ pr_info("Scheduler module ip_vs_%s not found\n",
+ u->sched_name);
+ ret = -ENOENT;
+ goto out_err;
+ }
}
if (u->pe_name && *u->pe_name) {
@@ -1240,10 +1244,12 @@ ip_vs_add_service(struct net *net, struct ip_vs_service_user_kern *u,
spin_lock_init(&svc->stats.lock);
/* Bind the scheduler */
- ret = ip_vs_bind_scheduler(svc, sched);
- if (ret)
- goto out_err;
- sched = NULL;
+ if (sched) {
+ ret = ip_vs_bind_scheduler(svc, sched);
+ if (ret)
+ goto out_err;
+ sched = NULL;
+ }
/* Bind the ct retriever */
RCU_INIT_POINTER(svc->pe, pe);
@@ -1291,17 +1297,20 @@ ip_vs_add_service(struct net *net, struct ip_vs_service_user_kern *u,
static int
ip_vs_edit_service(struct ip_vs_service *svc, struct ip_vs_service_user_kern *u)
{
- struct ip_vs_scheduler *sched, *old_sched;
+ struct ip_vs_scheduler *sched = NULL, *old_sched;
struct ip_vs_pe *pe = NULL, *old_pe = NULL;
int ret = 0;
/*
* Lookup the scheduler, by 'u->sched_name'
*/
- sched = ip_vs_scheduler_get(u->sched_name);
- if (sched == NULL) {
- pr_info("Scheduler module ip_vs_%s not found\n", u->sched_name);
- return -ENOENT;
+ if (strcmp(u->sched_name, "none")) {
+ sched = ip_vs_scheduler_get(u->sched_name);
+ if (!sched) {
+ pr_info("Scheduler module ip_vs_%s not found\n",
+ u->sched_name);
+ return -ENOENT;
+ }
}
old_sched = sched;
@@ -1329,14 +1338,20 @@ ip_vs_edit_service(struct ip_vs_service *svc, struct ip_vs_service_user_kern *u)
old_sched = rcu_dereference_protected(svc->scheduler, 1);
if (sched != old_sched) {
+ if (old_sched) {
+ ip_vs_unbind_scheduler(svc, old_sched);
+ RCU_INIT_POINTER(svc->scheduler, NULL);
+ /* Wait all svc->sched_data users */
+ synchronize_rcu();
+ }
/* Bind the new scheduler */
- ret = ip_vs_bind_scheduler(svc, sched);
- if (ret) {
- old_sched = sched;
- goto out;
+ if (sched) {
+ ret = ip_vs_bind_scheduler(svc, sched);
+ if (ret) {
+ ip_vs_scheduler_put(sched);
+ goto out;
+ }
}
- /* Unbind the old scheduler on success */
- ip_vs_unbind_scheduler(svc, old_sched);
}
/*
@@ -1982,6 +1997,7 @@ static int ip_vs_info_seq_show(struct seq_file *seq, void *v)
const struct ip_vs_iter *iter = seq->private;
const struct ip_vs_dest *dest;
struct ip_vs_scheduler *sched = rcu_dereference(svc->scheduler);
+ char *sched_name = sched ? sched->name : "none";
if (iter->table == ip_vs_svc_table) {
#ifdef CONFIG_IP_VS_IPV6
@@ -1990,18 +2006,18 @@ static int ip_vs_info_seq_show(struct seq_file *seq, void *v)
ip_vs_proto_name(svc->protocol),
&svc->addr.in6,
ntohs(svc->port),
- sched->name);
+ sched_name);
else
#endif
seq_printf(seq, "%s %08X:%04X %s %s ",
ip_vs_proto_name(svc->protocol),
ntohl(svc->addr.ip),
ntohs(svc->port),
- sched->name,
+ sched_name,
(svc->flags & IP_VS_SVC_F_ONEPACKET)?"ops ":"");
} else {
seq_printf(seq, "FWM %08X %s %s",
- svc->fwmark, sched->name,
+ svc->fwmark, sched_name,
(svc->flags & IP_VS_SVC_F_ONEPACKET)?"ops ":"");
}
@@ -2427,13 +2443,15 @@ ip_vs_copy_service(struct ip_vs_service_entry *dst, struct ip_vs_service *src)
{
struct ip_vs_scheduler *sched;
struct ip_vs_kstats kstats;
+ char *sched_name;
sched = rcu_dereference_protected(src->scheduler, 1);
+ sched_name = sched ? sched->name : "none";
dst->protocol = src->protocol;
dst->addr = src->addr.ip;
dst->port = src->port;
dst->fwmark = src->fwmark;
- strlcpy(dst->sched_name, sched->name, sizeof(dst->sched_name));
+ strlcpy(dst->sched_name, sched_name, sizeof(dst->sched_name));
dst->flags = src->flags;
dst->timeout = src->timeout / HZ;
dst->netmask = src->netmask;
@@ -2892,6 +2910,7 @@ static int ip_vs_genl_fill_service(struct sk_buff *skb,
struct ip_vs_flags flags = { .flags = svc->flags,
.mask = ~0 };
struct ip_vs_kstats kstats;
+ char *sched_name;
nl_service = nla_nest_start(skb, IPVS_CMD_ATTR_SERVICE);
if (!nl_service)
@@ -2910,8 +2929,9 @@ static int ip_vs_genl_fill_service(struct sk_buff *skb,
}
sched = rcu_dereference_protected(svc->scheduler, 1);
+ sched_name = sched ? sched->name : "none";
pe = rcu_dereference_protected(svc->pe, 1);
- if (nla_put_string(skb, IPVS_SVC_ATTR_SCHED_NAME, sched->name) ||
+ if (nla_put_string(skb, IPVS_SVC_ATTR_SCHED_NAME, sched_name) ||
(pe && nla_put_string(skb, IPVS_SVC_ATTR_PE_NAME, pe->name)) ||
nla_put(skb, IPVS_SVC_ATTR_FLAGS, sizeof(flags), &flags) ||
nla_put_u32(skb, IPVS_SVC_ATTR_TIMEOUT, svc->timeout / HZ) ||
diff --git a/net/netfilter/ipvs/ip_vs_sched.c b/net/netfilter/ipvs/ip_vs_sched.c
index 199760c71f39..7e8141647943 100644
--- a/net/netfilter/ipvs/ip_vs_sched.c
+++ b/net/netfilter/ipvs/ip_vs_sched.c
@@ -74,7 +74,7 @@ void ip_vs_unbind_scheduler(struct ip_vs_service *svc,
if (sched->done_service)
sched->done_service(svc);
- /* svc->scheduler can not be set to NULL */
+ /* svc->scheduler can be set to NULL only by caller */
}
@@ -147,21 +147,21 @@ void ip_vs_scheduler_put(struct ip_vs_scheduler *scheduler)
void ip_vs_scheduler_err(struct ip_vs_service *svc, const char *msg)
{
- struct ip_vs_scheduler *sched;
+ struct ip_vs_scheduler *sched = rcu_dereference(svc->scheduler);
+ char *sched_name = sched ? sched->name : "none";
- sched = rcu_dereference(svc->scheduler);
if (svc->fwmark) {
IP_VS_ERR_RL("%s: FWM %u 0x%08X - %s\n",
- sched->name, svc->fwmark, svc->fwmark, msg);
+ sched_name, svc->fwmark, svc->fwmark, msg);
#ifdef CONFIG_IP_VS_IPV6
} else if (svc->af == AF_INET6) {
IP_VS_ERR_RL("%s: %s [%pI6c]:%d - %s\n",
- sched->name, ip_vs_proto_name(svc->protocol),
+ sched_name, ip_vs_proto_name(svc->protocol),
&svc->addr.in6, ntohs(svc->port), msg);
#endif
} else {
IP_VS_ERR_RL("%s: %s %pI4:%d - %s\n",
- sched->name, ip_vs_proto_name(svc->protocol),
+ sched_name, ip_vs_proto_name(svc->protocol),
&svc->addr.ip, ntohs(svc->port), msg);
}
}
--
2.1.4
--
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