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ipmr: RCU protection for mfc_cache_array
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Use RCU & RTNL protection for mfc_cache_array[]

ipmr_cache_find() is called under rcu_read_lock();

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Eric Dumazet authored and David S. Miller committed Oct 4, 2010
1 parent 4c96870 commit a8c9486
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Showing 2 changed files with 48 additions and 40 deletions.
1 change: 1 addition & 0 deletions include/linux/mroute.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -213,6 +213,7 @@ struct mfc_cache {
unsigned char ttls[MAXVIFS]; /* TTL thresholds */
} res;
} mfc_un;
struct rcu_head rcu;
};

#define MFC_STATIC 1
Expand Down
87 changes: 47 additions & 40 deletions net/ipv4/ipmr.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -577,11 +577,18 @@ static int vif_delete(struct mr_table *mrt, int vifi, int notify,
return 0;
}

static inline void ipmr_cache_free(struct mfc_cache *c)
static void ipmr_cache_free_rcu(struct rcu_head *head)
{
struct mfc_cache *c = container_of(head, struct mfc_cache, rcu);

kmem_cache_free(mrt_cachep, c);
}

static inline void ipmr_cache_free(struct mfc_cache *c)
{
call_rcu(&c->rcu, ipmr_cache_free_rcu);
}

/* Destroy an unresolved cache entry, killing queued skbs
and reporting error to netlink readers.
*/
Expand Down Expand Up @@ -781,14 +788,15 @@ static int vif_add(struct net *net, struct mr_table *mrt,
return 0;
}

/* called with rcu_read_lock() */
static struct mfc_cache *ipmr_cache_find(struct mr_table *mrt,
__be32 origin,
__be32 mcastgrp)
{
int line = MFC_HASH(mcastgrp, origin);
struct mfc_cache *c;

list_for_each_entry(c, &mrt->mfc_cache_array[line], list) {
list_for_each_entry_rcu(c, &mrt->mfc_cache_array[line], list) {
if (c->mfc_origin == origin && c->mfc_mcastgrp == mcastgrp)
return c;
}
Expand All @@ -801,19 +809,20 @@ static struct mfc_cache *ipmr_cache_find(struct mr_table *mrt,
static struct mfc_cache *ipmr_cache_alloc(void)
{
struct mfc_cache *c = kmem_cache_zalloc(mrt_cachep, GFP_KERNEL);
if (c == NULL)
return NULL;
c->mfc_un.res.minvif = MAXVIFS;

if (c)
c->mfc_un.res.minvif = MAXVIFS;
return c;
}

static struct mfc_cache *ipmr_cache_alloc_unres(void)
{
struct mfc_cache *c = kmem_cache_zalloc(mrt_cachep, GFP_ATOMIC);
if (c == NULL)
return NULL;
skb_queue_head_init(&c->mfc_un.unres.unresolved);
c->mfc_un.unres.expires = jiffies + 10*HZ;

if (c) {
skb_queue_head_init(&c->mfc_un.unres.unresolved);
c->mfc_un.unres.expires = jiffies + 10*HZ;
}
return c;
}

Expand Down Expand Up @@ -1040,9 +1049,7 @@ static int ipmr_mfc_delete(struct mr_table *mrt, struct mfcctl *mfc)
list_for_each_entry_safe(c, next, &mrt->mfc_cache_array[line], list) {
if (c->mfc_origin == mfc->mfcc_origin.s_addr &&
c->mfc_mcastgrp == mfc->mfcc_mcastgrp.s_addr) {
write_lock_bh(&mrt_lock);
list_del(&c->list);
write_unlock_bh(&mrt_lock);
list_del_rcu(&c->list);

ipmr_cache_free(c);
return 0;
Expand Down Expand Up @@ -1095,9 +1102,7 @@ static int ipmr_mfc_add(struct net *net, struct mr_table *mrt,
if (!mrtsock)
c->mfc_flags |= MFC_STATIC;

write_lock_bh(&mrt_lock);
list_add(&c->list, &mrt->mfc_cache_array[line]);
write_unlock_bh(&mrt_lock);
list_add_rcu(&c->list, &mrt->mfc_cache_array[line]);

/*
* Check to see if we resolved a queued list. If so we
Expand Down Expand Up @@ -1149,12 +1154,9 @@ static void mroute_clean_tables(struct mr_table *mrt)
*/
for (i = 0; i < MFC_LINES; i++) {
list_for_each_entry_safe(c, next, &mrt->mfc_cache_array[i], list) {
if (c->mfc_flags&MFC_STATIC)
if (c->mfc_flags & MFC_STATIC)
continue;
write_lock_bh(&mrt_lock);
list_del(&c->list);
write_unlock_bh(&mrt_lock);

list_del_rcu(&c->list);
ipmr_cache_free(c);
}
}
Expand Down Expand Up @@ -1422,19 +1424,19 @@ int ipmr_ioctl(struct sock *sk, int cmd, void __user *arg)
if (copy_from_user(&sr, arg, sizeof(sr)))
return -EFAULT;

read_lock(&mrt_lock);
rcu_read_lock();
c = ipmr_cache_find(mrt, sr.src.s_addr, sr.grp.s_addr);
if (c) {
sr.pktcnt = c->mfc_un.res.pkt;
sr.bytecnt = c->mfc_un.res.bytes;
sr.wrong_if = c->mfc_un.res.wrong_if;
read_unlock(&mrt_lock);
rcu_read_unlock();

if (copy_to_user(arg, &sr, sizeof(sr)))
return -EFAULT;
return 0;
}
read_unlock(&mrt_lock);
rcu_read_unlock();
return -EADDRNOTAVAIL;
default:
return -ENOIOCTLCMD;
Expand Down Expand Up @@ -1764,7 +1766,7 @@ int ip_mr_input(struct sk_buff *skb)
}
}

read_lock(&mrt_lock);
/* already under rcu_read_lock() */
cache = ipmr_cache_find(mrt, ip_hdr(skb)->saddr, ip_hdr(skb)->daddr);

/*
Expand All @@ -1776,13 +1778,12 @@ int ip_mr_input(struct sk_buff *skb)
if (local) {
struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
ip_local_deliver(skb);
if (skb2 == NULL) {
read_unlock(&mrt_lock);
if (skb2 == NULL)
return -ENOBUFS;
}
skb = skb2;
}

read_lock(&mrt_lock);
vif = ipmr_find_vif(mrt, skb->dev);
if (vif >= 0) {
int err2 = ipmr_cache_unresolved(mrt, vif, skb);
Expand All @@ -1795,8 +1796,8 @@ int ip_mr_input(struct sk_buff *skb)
return -ENODEV;
}

read_lock(&mrt_lock);
ip_mr_forward(net, mrt, skb, cache, local);

read_unlock(&mrt_lock);

if (local)
Expand Down Expand Up @@ -1963,7 +1964,7 @@ int ipmr_get_route(struct net *net,
if (mrt == NULL)
return -ENOENT;

read_lock(&mrt_lock);
rcu_read_lock();
cache = ipmr_cache_find(mrt, rt->rt_src, rt->rt_dst);

if (cache == NULL) {
Expand All @@ -1973,18 +1974,21 @@ int ipmr_get_route(struct net *net,
int vif;

if (nowait) {
read_unlock(&mrt_lock);
rcu_read_unlock();
return -EAGAIN;
}

dev = skb->dev;
read_lock(&mrt_lock);
if (dev == NULL || (vif = ipmr_find_vif(mrt, dev)) < 0) {
read_unlock(&mrt_lock);
rcu_read_unlock();
return -ENODEV;
}
skb2 = skb_clone(skb, GFP_ATOMIC);
if (!skb2) {
read_unlock(&mrt_lock);
rcu_read_unlock();
return -ENOMEM;
}

Expand All @@ -1997,13 +2001,16 @@ int ipmr_get_route(struct net *net,
iph->version = 0;
err = ipmr_cache_unresolved(mrt, vif, skb2);
read_unlock(&mrt_lock);
rcu_read_unlock();
return err;
}

if (!nowait && (rtm->rtm_flags&RTM_F_NOTIFY))
read_lock(&mrt_lock);
if (!nowait && (rtm->rtm_flags & RTM_F_NOTIFY))
cache->mfc_flags |= MFC_NOTIFY;
err = __ipmr_fill_mroute(mrt, skb, cache, rtm);
read_unlock(&mrt_lock);
rcu_read_unlock();
return err;
}

Expand Down Expand Up @@ -2055,14 +2062,14 @@ static int ipmr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb)
s_h = cb->args[1];
s_e = cb->args[2];

read_lock(&mrt_lock);
rcu_read_lock();
ipmr_for_each_table(mrt, net) {
if (t < s_t)
goto next_table;
if (t > s_t)
s_h = 0;
for (h = s_h; h < MFC_LINES; h++) {
list_for_each_entry(mfc, &mrt->mfc_cache_array[h], list) {
list_for_each_entry_rcu(mfc, &mrt->mfc_cache_array[h], list) {
if (e < s_e)
goto next_entry;
if (ipmr_fill_mroute(mrt, skb,
Expand All @@ -2080,7 +2087,7 @@ static int ipmr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb)
t++;
}
done:
read_unlock(&mrt_lock);
rcu_read_unlock();

cb->args[2] = e;
cb->args[1] = h;
Expand Down Expand Up @@ -2213,14 +2220,14 @@ static struct mfc_cache *ipmr_mfc_seq_idx(struct net *net,
struct mr_table *mrt = it->mrt;
struct mfc_cache *mfc;

read_lock(&mrt_lock);
rcu_read_lock();
for (it->ct = 0; it->ct < MFC_LINES; it->ct++) {
it->cache = &mrt->mfc_cache_array[it->ct];
list_for_each_entry(mfc, it->cache, list)
list_for_each_entry_rcu(mfc, it->cache, list)
if (pos-- == 0)
return mfc;
}
read_unlock(&mrt_lock);
rcu_read_unlock();

spin_lock_bh(&mfc_unres_lock);
it->cache = &mrt->mfc_unres_queue;
Expand Down Expand Up @@ -2279,7 +2286,7 @@ static void *ipmr_mfc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
}

/* exhausted cache_array, show unresolved */
read_unlock(&mrt_lock);
rcu_read_unlock();
it->cache = &mrt->mfc_unres_queue;
it->ct = 0;

Expand All @@ -2302,7 +2309,7 @@ static void ipmr_mfc_seq_stop(struct seq_file *seq, void *v)
if (it->cache == &mrt->mfc_unres_queue)
spin_unlock_bh(&mfc_unres_lock);
else if (it->cache == &mrt->mfc_cache_array[it->ct])
read_unlock(&mrt_lock);
rcu_read_unlock();
}

static int ipmr_mfc_seq_show(struct seq_file *seq, void *v)
Expand Down Expand Up @@ -2426,7 +2433,7 @@ int __init ip_mr_init(void)

mrt_cachep = kmem_cache_create("ip_mrt_cache",
sizeof(struct mfc_cache),
0, SLAB_HWCACHE_ALIGN|SLAB_PANIC,
0, SLAB_HWCACHE_ALIGN | SLAB_PANIC,
NULL);
if (!mrt_cachep)
return -ENOMEM;
Expand Down

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