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[SCTP]: Add RCU synchronization around sctp_localaddr_list 

sctp_localaddr_list is modified dynamically via NETDEV_UP
and NETDEV_DOWN events, but there is not synchronization
between writer (even handler) and readers.  As a result,
the readers can access an entry that has been freed and
crash the sytem.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Sridhar Samdurala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Vlad Yasevich 2007-09-16 16:02:12 -07:00 committed by David S. Miller
parent ddeee3ce7f
commit 2930354799
6 changed files with 97 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/net/sctp/sctp.h
View File

@ -123,6 +123,7 @@
* sctp/protocol.c
*/
extern struct sock *sctp_get_ctl_sock(void);
extern void sctp_local_addr_free(struct rcu_head *head);
extern int sctp_copy_local_addr_list(struct sctp_bind_addr *,
sctp_scope_t, gfp_t gfp,
int flags);

6
include/net/sctp/structs.h
View File

@ -207,6 +207,9 @@ extern struct sctp_globals {
* It is a list of sctp_sockaddr_entry.
*/
struct list_head local_addr_list;
/* Lock that protects the local_addr_list writers */
spinlock_t addr_list_lock;
/* Flag to indicate if addip is enabled. */
int addip_enable;
@ -242,6 +245,7 @@ extern struct sctp_globals {
#define sctp_port_alloc_lock (sctp_globals.port_alloc_lock)
#define sctp_port_hashtable (sctp_globals.port_hashtable)
#define sctp_local_addr_list (sctp_globals.local_addr_list)
#define sctp_local_addr_lock (sctp_globals.addr_list_lock)
#define sctp_addip_enable (sctp_globals.addip_enable)
#define sctp_prsctp_enable (sctp_globals.prsctp_enable)
@ -737,8 +741,10 @@ const union sctp_addr *sctp_source(const struct sctp_chunk *chunk);
/* This is a structure for holding either an IPv6 or an IPv4 address. */
struct sctp_sockaddr_entry {
struct list_head list;
struct rcu_head rcu;
union sctp_addr a;
__u8 use_as_src;
__u8 valid;
};
typedef struct sctp_chunk *(sctp_packet_phandler_t)(struct sctp_association *);

2
net/sctp/bind_addr.c
View File

@ -163,8 +163,10 @@ int sctp_add_bind_addr(struct sctp_bind_addr *bp, union sctp_addr *new,
addr->a.v4.sin_port = htons(bp->port);
addr->use_as_src = use_as_src;
addr->valid = 1;
INIT_LIST_HEAD(&addr->list);
INIT_RCU_HEAD(&addr->rcu);
list_add_tail(&addr->list, &bp->address_list);
SCTP_DBG_OBJCNT_INC(addr);

34
net/sctp/ipv6.c
View File

@ -77,13 +77,18 @@
#include <asm/uaccess.h>
/* Event handler for inet6 address addition/deletion events. */
/* Event handler for inet6 address addition/deletion events.
* The sctp_local_addr_list needs to be protocted by a spin lock since
* multiple notifiers (say IPv4 and IPv6) may be running at the same
* time and thus corrupt the list.
* The reader side is protected with RCU.
*/
static int sctp_inet6addr_event(struct notifier_block *this, unsigned long ev,
void *ptr)
{
struct inet6_ifaddr *ifa = (struct inet6_ifaddr *)ptr;
struct sctp_sockaddr_entry *addr;
struct list_head *pos, *temp;
struct sctp_sockaddr_entry *addr = NULL;
struct sctp_sockaddr_entry *temp;
switch (ev) {
case NETDEV_UP:
@ -94,19 +99,26 @@ static int sctp_inet6addr_event(struct notifier_block *this, unsigned long ev,
memcpy(&addr->a.v6.sin6_addr, &ifa->addr,
sizeof(struct in6_addr));
addr->a.v6.sin6_scope_id = ifa->idev->dev->ifindex;
list_add_tail(&addr->list, &sctp_local_addr_list);
addr->valid = 1;
spin_lock_bh(&sctp_local_addr_lock);
list_add_tail_rcu(&addr->list, &sctp_local_addr_list);
spin_unlock_bh(&sctp_local_addr_lock);
}
break;
case NETDEV_DOWN:
list_for_each_safe(pos, temp, &sctp_local_addr_list) {
addr = list_entry(pos, struct sctp_sockaddr_entry, list);
if (ipv6_addr_equal(&addr->a.v6.sin6_addr, &ifa->addr)) {
list_del(pos);
kfree(addr);
spin_lock_bh(&sctp_local_addr_lock);
list_for_each_entry_safe(addr, temp,
&sctp_local_addr_list, list) {
if (ipv6_addr_equal(&addr->a.v6.sin6_addr,
&ifa->addr)) {
addr->valid = 0;
list_del_rcu(&addr->list);
break;
}
}
spin_unlock_bh(&sctp_local_addr_lock);
if (addr && !addr->valid)
call_rcu(&addr->rcu, sctp_local_addr_free);
break;
}
@ -367,7 +379,9 @@ static void sctp_v6_copy_addrlist(struct list_head *addrlist,
addr->a.v6.sin6_port = 0;
addr->a.v6.sin6_addr = ifp->addr;
addr->a.v6.sin6_scope_id = dev->ifindex;
addr->valid = 1;
INIT_LIST_HEAD(&addr->list);
INIT_RCU_HEAD(&addr->rcu);
list_add_tail(&addr->list, addrlist);
}
}

54
net/sctp/protocol.c
View File

@ -153,6 +153,9 @@ static void sctp_v4_copy_addrlist(struct list_head *addrlist,
addr->a.v4.sin_family = AF_INET;
addr->a.v4.sin_port = 0;
addr->a.v4.sin_addr.s_addr = ifa->ifa_local;
addr->valid = 1;
INIT_LIST_HEAD(&addr->list);
INIT_RCU_HEAD(&addr->rcu);
list_add_tail(&addr->list, addrlist);
}
}
@ -192,16 +195,24 @@ static void sctp_free_local_addr_list(void)
}
}
void sctp_local_addr_free(struct rcu_head *head)
{
struct sctp_sockaddr_entry *e = container_of(head,
struct sctp_sockaddr_entry, rcu);
kfree(e);
}
/* Copy the local addresses which are valid for 'scope' into 'bp'. */
int sctp_copy_local_addr_list(struct sctp_bind_addr *bp, sctp_scope_t scope,
gfp_t gfp, int copy_flags)
{
struct sctp_sockaddr_entry *addr;
int error = 0;
struct list_head *pos, *temp;
list_for_each_safe(pos, temp, &sctp_local_addr_list) {
addr = list_entry(pos, struct sctp_sockaddr_entry, list);
rcu_read_lock();
list_for_each_entry_rcu(addr, &sctp_local_addr_list, list) {
if (!addr->valid)
continue;
if (sctp_in_scope(&addr->a, scope)) {
/* Now that the address is in scope, check to see if
* the address type is really supported by the local
@ -221,6 +232,7 @@ int sctp_copy_local_addr_list(struct sctp_bind_addr *bp, sctp_scope_t scope,
}
end_copy:
rcu_read_unlock();
return error;
}
@ -600,13 +612,18 @@ static void sctp_v4_seq_dump_addr(struct seq_file *seq, union sctp_addr *addr)
seq_printf(seq, "%d.%d.%d.%d ", NIPQUAD(addr->v4.sin_addr));
}
/* Event handler for inet address addition/deletion events. */
/* Event handler for inet address addition/deletion events.
* The sctp_local_addr_list needs to be protocted by a spin lock since
* multiple notifiers (say IPv4 and IPv6) may be running at the same
* time and thus corrupt the list.
* The reader side is protected with RCU.
*/
static int sctp_inetaddr_event(struct notifier_block *this, unsigned long ev,
void *ptr)
{
struct in_ifaddr *ifa = (struct in_ifaddr *)ptr;
struct sctp_sockaddr_entry *addr;
struct list_head *pos, *temp;
struct sctp_sockaddr_entry *addr = NULL;
struct sctp_sockaddr_entry *temp;
switch (ev) {
case NETDEV_UP:
@ -615,19 +632,25 @@ static int sctp_inetaddr_event(struct notifier_block *this, unsigned long ev,
addr->a.v4.sin_family = AF_INET;
addr->a.v4.sin_port = 0;
addr->a.v4.sin_addr.s_addr = ifa->ifa_local;
list_add_tail(&addr->list, &sctp_local_addr_list);
addr->valid = 1;
spin_lock_bh(&sctp_local_addr_lock);
list_add_tail_rcu(&addr->list, &sctp_local_addr_list);
spin_unlock_bh(&sctp_local_addr_lock);
}
break;
case NETDEV_DOWN:
list_for_each_safe(pos, temp, &sctp_local_addr_list) {
addr = list_entry(pos, struct sctp_sockaddr_entry, list);
spin_lock_bh(&sctp_local_addr_lock);
list_for_each_entry_safe(addr, temp,
&sctp_local_addr_list, list) {
if (addr->a.v4.sin_addr.s_addr == ifa->ifa_local) {
list_del(pos);
kfree(addr);
addr->valid = 0;
list_del_rcu(&addr->list);
break;
}
}
spin_unlock_bh(&sctp_local_addr_lock);
if (addr && !addr->valid)
call_rcu(&addr->rcu, sctp_local_addr_free);
break;
}
@ -1160,6 +1183,7 @@ SCTP_STATIC __init int sctp_init(void)
/* Initialize the local address list. */
INIT_LIST_HEAD(&sctp_local_addr_list);
spin_lock_init(&sctp_local_addr_lock);
sctp_get_local_addr_list();
/* Register notifier for inet address additions/deletions. */
@ -1227,6 +1251,9 @@ SCTP_STATIC __exit void sctp_exit(void)
sctp_v6_del_protocol();
inet_del_protocol(&sctp_protocol, IPPROTO_SCTP);
/* Unregister notifier for inet address additions/deletions. */
unregister_inetaddr_notifier(&sctp_inetaddr_notifier);
/* Free the local address list. */
sctp_free_local_addr_list();
@ -1240,9 +1267,6 @@ SCTP_STATIC __exit void sctp_exit(void)
inet_unregister_protosw(&sctp_stream_protosw);
inet_unregister_protosw(&sctp_seqpacket_protosw);
/* Unregister notifier for inet address additions/deletions. */
unregister_inetaddr_notifier(&sctp_inetaddr_notifier);
sctp_sysctl_unregister();
list_del(&sctp_ipv4_specific.list);

38
net/sctp/socket.c
View File

@ -4057,9 +4057,9 @@ static int sctp_getsockopt_local_addrs_num_old(struct sock *sk, int len,
int __user *optlen)
{
sctp_assoc_t id;
struct list_head *pos;
struct sctp_bind_addr *bp;
struct sctp_association *asoc;
struct list_head *pos, *temp;
struct sctp_sockaddr_entry *addr;
rwlock_t *addr_lock;
int cnt = 0;
@ -4096,15 +4096,19 @@ static int sctp_getsockopt_local_addrs_num_old(struct sock *sk, int len,
addr = list_entry(bp->address_list.next,
struct sctp_sockaddr_entry, list);
if (sctp_is_any(&addr->a)) {
list_for_each_safe(pos, temp, &sctp_local_addr_list) {
addr = list_entry(pos,
struct sctp_sockaddr_entry,
list);
rcu_read_lock();
list_for_each_entry_rcu(addr,
&sctp_local_addr_list, list) {
if (!addr->valid)
continue;
if ((PF_INET == sk->sk_family) &&
(AF_INET6 == addr->a.sa.sa_family))
continue;
cnt++;
}
rcu_read_unlock();
} else {
cnt = 1;
}
@ -4127,14 +4131,16 @@ static int sctp_copy_laddrs_old(struct sock *sk, __u16 port,
int max_addrs, void *to,
int *bytes_copied)
{
struct list_head *pos, *next;
struct sctp_sockaddr_entry *addr;
union sctp_addr temp;
int cnt = 0;
int addrlen;
list_for_each_safe(pos, next, &sctp_local_addr_list) {
addr = list_entry(pos, struct sctp_sockaddr_entry, list);
rcu_read_lock();
list_for_each_entry_rcu(addr, &sctp_local_addr_list, list) {
if (!addr->valid)
continue;
if ((PF_INET == sk->sk_family) &&
(AF_INET6 == addr->a.sa.sa_family))
continue;
@ -4149,6 +4155,7 @@ static int sctp_copy_laddrs_old(struct sock *sk, __u16 port,
cnt ++;
if (cnt >= max_addrs) break;
}
rcu_read_unlock();
return cnt;
}
@ -4156,14 +4163,16 @@ static int sctp_copy_laddrs_old(struct sock *sk, __u16 port,
static int sctp_copy_laddrs(struct sock *sk, __u16 port, void *to,
size_t space_left, int *bytes_copied)
{
struct list_head *pos, *next;
struct sctp_sockaddr_entry *addr;
union sctp_addr temp;
int cnt = 0;
int addrlen;
list_for_each_safe(pos, next, &sctp_local_addr_list) {
addr = list_entry(pos, struct sctp_sockaddr_entry, list);
rcu_read_lock();
list_for_each_entry_rcu(addr, &sctp_local_addr_list, list) {
if (!addr->valid)
continue;
if ((PF_INET == sk->sk_family) &&
(AF_INET6 == addr->a.sa.sa_family))
continue;
@ -4171,8 +4180,10 @@ static int sctp_copy_laddrs(struct sock *sk, __u16 port, void *to,
sctp_get_pf_specific(sk->sk_family)->addr_v4map(sctp_sk(sk),
&temp);
addrlen = sctp_get_af_specific(temp.sa.sa_family)->sockaddr_len;
if (space_left < addrlen)
return -ENOMEM;
if (space_left < addrlen) {
cnt = -ENOMEM;
break;
}
memcpy(to, &temp, addrlen);
to += addrlen;
@ -4180,6 +4191,7 @@ static int sctp_copy_laddrs(struct sock *sk, __u16 port, void *to,
space_left -= addrlen;
*bytes_copied += addrlen;
}
rcu_read_unlock();
return cnt;
}