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Merge branch 'net-fix-mcast-rcu-splats'
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Paolo Abeni says:

====================
net: fix mcast RCU splats

This series addresses the RCU splat triggered by the forwarding
mroute tests.

The first patch does not address any specific issue, but makes the
following ones more clear. Patch 2 and 3 address the issue for ipv6 and
ipv4 respectively.
====================

Link: https://patch.msgid.link/cover.1732289799.git.pabeni@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Paolo Abeni committed Nov 28, 2024
2 parents 663a917 + fc9c273 commit 0dd2985
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Showing 2 changed files with 84 additions and 24 deletions.
56 changes: 43 additions & 13 deletions net/ipv4/ipmr.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -120,6 +120,11 @@ static void ipmr_expire_process(struct timer_list *t);
lockdep_rtnl_is_held() || \
list_empty(&net->ipv4.mr_tables))

static bool ipmr_can_free_table(struct net *net)
{
return !check_net(net) || !net->ipv4.mr_rules_ops;
}

static struct mr_table *ipmr_mr_table_iter(struct net *net,
struct mr_table *mrt)
{
Expand All @@ -137,7 +142,7 @@ static struct mr_table *ipmr_mr_table_iter(struct net *net,
return ret;
}

static struct mr_table *ipmr_get_table(struct net *net, u32 id)
static struct mr_table *__ipmr_get_table(struct net *net, u32 id)
{
struct mr_table *mrt;

Expand All @@ -148,6 +153,16 @@ static struct mr_table *ipmr_get_table(struct net *net, u32 id)
return NULL;
}

static struct mr_table *ipmr_get_table(struct net *net, u32 id)
{
struct mr_table *mrt;

rcu_read_lock();
mrt = __ipmr_get_table(net, id);
rcu_read_unlock();
return mrt;
}

static int ipmr_fib_lookup(struct net *net, struct flowi4 *flp4,
struct mr_table **mrt)
{
Expand Down Expand Up @@ -189,7 +204,7 @@ static int ipmr_rule_action(struct fib_rule *rule, struct flowi *flp,

arg->table = fib_rule_get_table(rule, arg);

mrt = ipmr_get_table(rule->fr_net, arg->table);
mrt = __ipmr_get_table(rule->fr_net, arg->table);
if (!mrt)
return -EAGAIN;
res->mrt = mrt;
Expand Down Expand Up @@ -302,6 +317,11 @@ EXPORT_SYMBOL(ipmr_rule_default);
#define ipmr_for_each_table(mrt, net) \
for (mrt = net->ipv4.mrt; mrt; mrt = NULL)

static bool ipmr_can_free_table(struct net *net)
{
return !check_net(net);
}

static struct mr_table *ipmr_mr_table_iter(struct net *net,
struct mr_table *mrt)
{
Expand All @@ -315,6 +335,8 @@ static struct mr_table *ipmr_get_table(struct net *net, u32 id)
return net->ipv4.mrt;
}

#define __ipmr_get_table ipmr_get_table

static int ipmr_fib_lookup(struct net *net, struct flowi4 *flp4,
struct mr_table **mrt)
{
Expand Down Expand Up @@ -403,7 +425,7 @@ static struct mr_table *ipmr_new_table(struct net *net, u32 id)
if (id != RT_TABLE_DEFAULT && id >= 1000000000)
return ERR_PTR(-EINVAL);

mrt = ipmr_get_table(net, id);
mrt = __ipmr_get_table(net, id);
if (mrt)
return mrt;

Expand All @@ -413,6 +435,10 @@ static struct mr_table *ipmr_new_table(struct net *net, u32 id)

static void ipmr_free_table(struct mr_table *mrt)
{
struct net *net = read_pnet(&mrt->net);

DEBUG_NET_WARN_ON_ONCE(!ipmr_can_free_table(net));

timer_shutdown_sync(&mrt->ipmr_expire_timer);
mroute_clean_tables(mrt, MRT_FLUSH_VIFS | MRT_FLUSH_VIFS_STATIC |
MRT_FLUSH_MFC | MRT_FLUSH_MFC_STATIC);
Expand Down Expand Up @@ -1374,7 +1400,7 @@ int ip_mroute_setsockopt(struct sock *sk, int optname, sockptr_t optval,
goto out_unlock;
}

mrt = ipmr_get_table(net, raw_sk(sk)->ipmr_table ? : RT_TABLE_DEFAULT);
mrt = __ipmr_get_table(net, raw_sk(sk)->ipmr_table ? : RT_TABLE_DEFAULT);
if (!mrt) {
ret = -ENOENT;
goto out_unlock;
Expand Down Expand Up @@ -2262,11 +2288,13 @@ int ipmr_get_route(struct net *net, struct sk_buff *skb,
struct mr_table *mrt;
int err;

mrt = ipmr_get_table(net, RT_TABLE_DEFAULT);
if (!mrt)
rcu_read_lock();
mrt = __ipmr_get_table(net, RT_TABLE_DEFAULT);
if (!mrt) {
rcu_read_unlock();
return -ENOENT;
}

rcu_read_lock();
cache = ipmr_cache_find(mrt, saddr, daddr);
if (!cache && skb->dev) {
int vif = ipmr_find_vif(mrt, skb->dev);
Expand Down Expand Up @@ -2550,7 +2578,7 @@ static int ipmr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
grp = nla_get_in_addr_default(tb[RTA_DST], 0);
tableid = nla_get_u32_default(tb[RTA_TABLE], 0);

mrt = ipmr_get_table(net, tableid ? tableid : RT_TABLE_DEFAULT);
mrt = __ipmr_get_table(net, tableid ? tableid : RT_TABLE_DEFAULT);
if (!mrt) {
err = -ENOENT;
goto errout_free;
Expand Down Expand Up @@ -2604,7 +2632,7 @@ static int ipmr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb)
if (filter.table_id) {
struct mr_table *mrt;

mrt = ipmr_get_table(sock_net(skb->sk), filter.table_id);
mrt = __ipmr_get_table(sock_net(skb->sk), filter.table_id);
if (!mrt) {
if (rtnl_msg_family(cb->nlh) != RTNL_FAMILY_IPMR)
return skb->len;
Expand Down Expand Up @@ -2712,7 +2740,7 @@ static int rtm_to_ipmr_mfcc(struct net *net, struct nlmsghdr *nlh,
break;
}
}
mrt = ipmr_get_table(net, tblid);
mrt = __ipmr_get_table(net, tblid);
if (!mrt) {
ret = -ENOENT;
goto out;
Expand Down Expand Up @@ -2920,13 +2948,15 @@ static void *ipmr_vif_seq_start(struct seq_file *seq, loff_t *pos)
struct net *net = seq_file_net(seq);
struct mr_table *mrt;

mrt = ipmr_get_table(net, RT_TABLE_DEFAULT);
if (!mrt)
rcu_read_lock();
mrt = __ipmr_get_table(net, RT_TABLE_DEFAULT);
if (!mrt) {
rcu_read_unlock();
return ERR_PTR(-ENOENT);
}

iter->mrt = mrt;

rcu_read_lock();
return mr_vif_seq_start(seq, pos);
}

Expand Down
52 changes: 41 additions & 11 deletions net/ipv6/ip6mr.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -108,6 +108,11 @@ static void ipmr_expire_process(struct timer_list *t);
lockdep_rtnl_is_held() || \
list_empty(&net->ipv6.mr6_tables))

static bool ip6mr_can_free_table(struct net *net)
{
return !check_net(net) || !net->ipv6.mr6_rules_ops;
}

static struct mr_table *ip6mr_mr_table_iter(struct net *net,
struct mr_table *mrt)
{
Expand All @@ -125,7 +130,7 @@ static struct mr_table *ip6mr_mr_table_iter(struct net *net,
return ret;
}

static struct mr_table *ip6mr_get_table(struct net *net, u32 id)
static struct mr_table *__ip6mr_get_table(struct net *net, u32 id)
{
struct mr_table *mrt;

Expand All @@ -136,6 +141,16 @@ static struct mr_table *ip6mr_get_table(struct net *net, u32 id)
return NULL;
}

static struct mr_table *ip6mr_get_table(struct net *net, u32 id)
{
struct mr_table *mrt;

rcu_read_lock();
mrt = __ip6mr_get_table(net, id);
rcu_read_unlock();
return mrt;
}

static int ip6mr_fib_lookup(struct net *net, struct flowi6 *flp6,
struct mr_table **mrt)
{
Expand Down Expand Up @@ -177,7 +192,7 @@ static int ip6mr_rule_action(struct fib_rule *rule, struct flowi *flp,

arg->table = fib_rule_get_table(rule, arg);

mrt = ip6mr_get_table(rule->fr_net, arg->table);
mrt = __ip6mr_get_table(rule->fr_net, arg->table);
if (!mrt)
return -EAGAIN;
res->mrt = mrt;
Expand Down Expand Up @@ -291,6 +306,11 @@ EXPORT_SYMBOL(ip6mr_rule_default);
#define ip6mr_for_each_table(mrt, net) \
for (mrt = net->ipv6.mrt6; mrt; mrt = NULL)

static bool ip6mr_can_free_table(struct net *net)
{
return !check_net(net);
}

static struct mr_table *ip6mr_mr_table_iter(struct net *net,
struct mr_table *mrt)
{
Expand All @@ -304,6 +324,8 @@ static struct mr_table *ip6mr_get_table(struct net *net, u32 id)
return net->ipv6.mrt6;
}

#define __ip6mr_get_table ip6mr_get_table

static int ip6mr_fib_lookup(struct net *net, struct flowi6 *flp6,
struct mr_table **mrt)
{
Expand Down Expand Up @@ -382,7 +404,7 @@ static struct mr_table *ip6mr_new_table(struct net *net, u32 id)
{
struct mr_table *mrt;

mrt = ip6mr_get_table(net, id);
mrt = __ip6mr_get_table(net, id);
if (mrt)
return mrt;

Expand All @@ -392,6 +414,10 @@ static struct mr_table *ip6mr_new_table(struct net *net, u32 id)

static void ip6mr_free_table(struct mr_table *mrt)
{
struct net *net = read_pnet(&mrt->net);

DEBUG_NET_WARN_ON_ONCE(!ip6mr_can_free_table(net));

timer_shutdown_sync(&mrt->ipmr_expire_timer);
mroute_clean_tables(mrt, MRT6_FLUSH_MIFS | MRT6_FLUSH_MIFS_STATIC |
MRT6_FLUSH_MFC | MRT6_FLUSH_MFC_STATIC);
Expand All @@ -411,13 +437,15 @@ static void *ip6mr_vif_seq_start(struct seq_file *seq, loff_t *pos)
struct net *net = seq_file_net(seq);
struct mr_table *mrt;

mrt = ip6mr_get_table(net, RT6_TABLE_DFLT);
if (!mrt)
rcu_read_lock();
mrt = __ip6mr_get_table(net, RT6_TABLE_DFLT);
if (!mrt) {
rcu_read_unlock();
return ERR_PTR(-ENOENT);
}

iter->mrt = mrt;

rcu_read_lock();
return mr_vif_seq_start(seq, pos);
}

Expand Down Expand Up @@ -2278,11 +2306,13 @@ int ip6mr_get_route(struct net *net, struct sk_buff *skb, struct rtmsg *rtm,
struct mfc6_cache *cache;
struct rt6_info *rt = dst_rt6_info(skb_dst(skb));

mrt = ip6mr_get_table(net, RT6_TABLE_DFLT);
if (!mrt)
rcu_read_lock();
mrt = __ip6mr_get_table(net, RT6_TABLE_DFLT);
if (!mrt) {
rcu_read_unlock();
return -ENOENT;
}

rcu_read_lock();
cache = ip6mr_cache_find(mrt, &rt->rt6i_src.addr, &rt->rt6i_dst.addr);
if (!cache && skb->dev) {
int vif = ip6mr_find_vif(mrt, skb->dev);
Expand Down Expand Up @@ -2562,7 +2592,7 @@ static int ip6mr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
grp = nla_get_in6_addr(tb[RTA_DST]);
tableid = nla_get_u32_default(tb[RTA_TABLE], 0);

mrt = ip6mr_get_table(net, tableid ?: RT_TABLE_DEFAULT);
mrt = __ip6mr_get_table(net, tableid ?: RT_TABLE_DEFAULT);
if (!mrt) {
NL_SET_ERR_MSG_MOD(extack, "MR table does not exist");
return -ENOENT;
Expand Down Expand Up @@ -2609,7 +2639,7 @@ static int ip6mr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb)
if (filter.table_id) {
struct mr_table *mrt;

mrt = ip6mr_get_table(sock_net(skb->sk), filter.table_id);
mrt = __ip6mr_get_table(sock_net(skb->sk), filter.table_id);
if (!mrt) {
if (rtnl_msg_family(cb->nlh) != RTNL_FAMILY_IP6MR)
return skb->len;
Expand Down

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