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igmp: fix ip_mc_sf_allow race [v5] 

Almost all igmp functions accessing inet->mc_list are protected by
rtnl_lock(), but there is one exception which is ip_mc_sf_allow(),
so there is a chance of either ip_mc_drop_socket or ip_mc_leave_group
remove an entry while ip_mc_sf_allow is running causing a crash.

Signed-off-by: Flavio Leitner <fleitner@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Flavio Leitner 2010-02-02 07:32:29 -08:00 committed by David S. Miller
parent 8b64056dac
commit c85bb41e93
2 changed files with 64 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/igmp.h
View File

@ -153,6 +153,7 @@ extern int sysctl_igmp_max_msf;
struct ip_sf_socklist {
unsigned int sl_max;
unsigned int sl_count;
struct rcu_head rcu;
__be32 sl_addr[0];
};
@ -170,6 +171,7 @@ struct ip_mc_socklist {
struct ip_mreqn multi;
unsigned int sfmode; /* MCAST_{INCLUDE,EXCLUDE} */
struct ip_sf_socklist *sflist;
struct rcu_head rcu;
};
struct ip_sf_list {

83
net/ipv4/igmp.c
View File

@ -1799,7 +1799,7 @@ int ip_mc_join_group(struct sock *sk , struct ip_mreqn *imr)
iml->next = inet->mc_list;
iml->sflist = NULL;
iml->sfmode = MCAST_EXCLUDE;
inet->mc_list = iml;
rcu_assign_pointer(inet->mc_list, iml);
ip_mc_inc_group(in_dev, addr);
err = 0;
done:
@ -1807,24 +1807,46 @@ done:
return err;
}
static void ip_sf_socklist_reclaim(struct rcu_head *rp)
{
struct ip_sf_socklist *psf;
psf = container_of(rp, struct ip_sf_socklist, rcu);
/* sk_omem_alloc should have been decreased by the caller*/
kfree(psf);
}
static int ip_mc_leave_src(struct sock *sk, struct ip_mc_socklist *iml,
struct in_device *in_dev)
{
struct ip_sf_socklist *psf = iml->sflist;
int err;
if (iml->sflist == NULL) {
if (psf == NULL) {
/* any-source empty exclude case */
return ip_mc_del_src(in_dev, &iml->multi.imr_multiaddr.s_addr,
iml->sfmode, 0, NULL, 0);
}
err = ip_mc_del_src(in_dev, &iml->multi.imr_multiaddr.s_addr,
iml->sfmode, iml->sflist->sl_count,
iml->sflist->sl_addr, 0);
sock_kfree_s(sk, iml->sflist, IP_SFLSIZE(iml->sflist->sl_max));
iml->sflist = NULL;
iml->sfmode, psf->sl_count, psf->sl_addr, 0);
rcu_assign_pointer(iml->sflist, NULL);
/* decrease mem now to avoid the memleak warning */
atomic_sub(IP_SFLSIZE(psf->sl_max), &sk->sk_omem_alloc);
call_rcu(&psf->rcu, ip_sf_socklist_reclaim);
return err;
}
static void ip_mc_socklist_reclaim(struct rcu_head *rp)
{
struct ip_mc_socklist *iml;
iml = container_of(rp, struct ip_mc_socklist, rcu);
/* sk_omem_alloc should have been decreased by the caller*/
kfree(iml);
}
/*
* Ask a socket to leave a group.
*/
@ -1854,12 +1876,14 @@ int ip_mc_leave_group(struct sock *sk, struct ip_mreqn *imr)
(void) ip_mc_leave_src(sk, iml, in_dev);
*imlp = iml->next;
rcu_assign_pointer(*imlp, iml->next);
if (in_dev)
ip_mc_dec_group(in_dev, group);
rtnl_unlock();
sock_kfree_s(sk, iml, sizeof(*iml));
/* decrease mem now to avoid the memleak warning */
atomic_sub(sizeof(*iml), &sk->sk_omem_alloc);
call_rcu(&iml->rcu, ip_mc_socklist_reclaim);
return 0;
}
if (!in_dev)
@ -1974,9 +1998,12 @@ int ip_mc_source(int add, int omode, struct sock *sk, struct
if (psl) {
for (i=0; i<psl->sl_count; i++)
newpsl->sl_addr[i] = psl->sl_addr[i];
sock_kfree_s(sk, psl, IP_SFLSIZE(psl->sl_max));
/* decrease mem now to avoid the memleak warning */
atomic_sub(IP_SFLSIZE(psl->sl_max), &sk->sk_omem_alloc);
call_rcu(&psl->rcu, ip_sf_socklist_reclaim);
}
pmc->sflist = psl = newpsl;
rcu_assign_pointer(pmc->sflist, newpsl);
psl = newpsl;
}
rv = 1; /* > 0 for insert logic below if sl_count is 0 */
for (i=0; i<psl->sl_count; i++) {
@ -2072,11 +2099,13 @@ int ip_mc_msfilter(struct sock *sk, struct ip_msfilter *msf, int ifindex)
if (psl) {
(void) ip_mc_del_src(in_dev, &msf->imsf_multiaddr, pmc->sfmode,
psl->sl_count, psl->sl_addr, 0);
sock_kfree_s(sk, psl, IP_SFLSIZE(psl->sl_max));
/* decrease mem now to avoid the memleak warning */
atomic_sub(IP_SFLSIZE(psl->sl_max), &sk->sk_omem_alloc);
call_rcu(&psl->rcu, ip_sf_socklist_reclaim);
} else
(void) ip_mc_del_src(in_dev, &msf->imsf_multiaddr, pmc->sfmode,
0, NULL, 0);
pmc->sflist = newpsl;
rcu_assign_pointer(pmc->sflist, newpsl);
pmc->sfmode = msf->imsf_fmode;
err = 0;
done:
@ -2209,30 +2238,40 @@ int ip_mc_sf_allow(struct sock *sk, __be32 loc_addr, __be32 rmt_addr, int dif)
struct ip_mc_socklist *pmc;
struct ip_sf_socklist *psl;
int i;
int ret;
ret = 1;
if (!ipv4_is_multicast(loc_addr))
return 1;
goto out;
for (pmc=inet->mc_list; pmc; pmc=pmc->next) {
rcu_read_lock();
for (pmc=rcu_dereference(inet->mc_list); pmc; pmc=rcu_dereference(pmc->next)) {
if (pmc->multi.imr_multiaddr.s_addr == loc_addr &&
pmc->multi.imr_ifindex == dif)
break;
}
ret = inet->mc_all;
if (!pmc)
return inet->mc_all;
goto unlock;
psl = pmc->sflist;
ret = (pmc->sfmode == MCAST_EXCLUDE);
if (!psl)
return pmc->sfmode == MCAST_EXCLUDE;
goto unlock;
for (i=0; i<psl->sl_count; i++) {
if (psl->sl_addr[i] == rmt_addr)
break;
}
ret = 0;
if (pmc->sfmode == MCAST_INCLUDE && i >= psl->sl_count)
return 0;
goto unlock;
if (pmc->sfmode == MCAST_EXCLUDE && i < psl->sl_count)
return 0;
return 1;
goto unlock;
ret = 1;
unlock:
rcu_read_unlock();
out:
return ret;
}
/*
@ -2251,7 +2290,7 @@ void ip_mc_drop_socket(struct sock *sk)
rtnl_lock();
while ((iml = inet->mc_list) != NULL) {
struct in_device *in_dev;
inet->mc_list = iml->next;
rcu_assign_pointer(inet->mc_list, iml->next);
in_dev = inetdev_by_index(net, iml->multi.imr_ifindex);
(void) ip_mc_leave_src(sk, iml, in_dev);
@ -2259,7 +2298,9 @@ void ip_mc_drop_socket(struct sock *sk)
ip_mc_dec_group(in_dev, iml->multi.imr_multiaddr.s_addr);
in_dev_put(in_dev);
}
sock_kfree_s(sk, iml, sizeof(*iml));
/* decrease mem now to avoid the memleak warning */
atomic_sub(sizeof(*iml), &sk->sk_omem_alloc);
call_rcu(&iml->rcu, ip_mc_socklist_reclaim);
}
rtnl_unlock();
}