Commit fda9ef5d authored by Dmitry Mishin's avatar Dmitry Mishin Committed by David S. Miller

[NET]: Fix sk->sk_filter field access

Function sk_filter() is called from tcp_v{4,6}_rcv() functions with arg
needlock = 0, while socket is not locked at that moment. In order to avoid
this and similar issues in the future, use rcu for sk->sk_filter field read
protection.
Signed-off-by: default avatarDmitry Mishin <dim@openvz.org>
Signed-off-by: default avatarAlexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Signed-off-by: default avatarKirill Korotaev <dev@openvz.org>
parent dc435e6d
......@@ -25,10 +25,10 @@
struct sock_filter /* Filter block */
{
__u16 code; /* Actual filter code */
__u8 jt; /* Jump true */
__u8 jf; /* Jump false */
__u32 k; /* Generic multiuse field */
__u16 code; /* Actual filter code */
__u8 jt; /* Jump true */
__u8 jf; /* Jump false */
__u32 k; /* Generic multiuse field */
};
struct sock_fprog /* Required for SO_ATTACH_FILTER. */
......@@ -41,8 +41,9 @@ struct sock_fprog /* Required for SO_ATTACH_FILTER. */
struct sk_filter
{
atomic_t refcnt;
unsigned int len; /* Number of filter blocks */
struct sock_filter insns[0];
unsigned int len; /* Number of filter blocks */
struct rcu_head rcu;
struct sock_filter insns[0];
};
static inline unsigned int sk_filter_len(struct sk_filter *fp)
......
......@@ -862,30 +862,24 @@ extern void sock_init_data(struct socket *sock, struct sock *sk);
*
*/
static inline int sk_filter(struct sock *sk, struct sk_buff *skb, int needlock)
static inline int sk_filter(struct sock *sk, struct sk_buff *skb)
{
int err;
struct sk_filter *filter;
err = security_sock_rcv_skb(sk, skb);
if (err)
return err;
if (sk->sk_filter) {
struct sk_filter *filter;
if (needlock)
bh_lock_sock(sk);
filter = sk->sk_filter;
if (filter) {
unsigned int pkt_len = sk_run_filter(skb, filter->insns,
filter->len);
err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM;
}
if (needlock)
bh_unlock_sock(sk);
rcu_read_lock_bh();
filter = sk->sk_filter;
if (filter) {
unsigned int pkt_len = sk_run_filter(skb, filter->insns,
filter->len);
err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM;
}
rcu_read_unlock_bh();
return err;
}
......@@ -897,6 +891,12 @@ static inline int sk_filter(struct sock *sk, struct sk_buff *skb, int needlock)
* Remove a filter from a socket and release its resources.
*/
static inline void sk_filter_rcu_free(struct rcu_head *rcu)
{
struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu);
kfree(fp);
}
static inline void sk_filter_release(struct sock *sk, struct sk_filter *fp)
{
unsigned int size = sk_filter_len(fp);
......@@ -904,7 +904,7 @@ static inline void sk_filter_release(struct sock *sk, struct sk_filter *fp)
atomic_sub(size, &sk->sk_omem_alloc);
if (atomic_dec_and_test(&fp->refcnt))
kfree(fp);
call_rcu_bh(&fp->rcu, sk_filter_rcu_free);
}
static inline void sk_filter_charge(struct sock *sk, struct sk_filter *fp)
......
......@@ -422,10 +422,10 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
if (!err) {
struct sk_filter *old_fp;
spin_lock_bh(&sk->sk_lock.slock);
old_fp = sk->sk_filter;
sk->sk_filter = fp;
spin_unlock_bh(&sk->sk_lock.slock);
rcu_read_lock_bh();
old_fp = rcu_dereference(sk->sk_filter);
rcu_assign_pointer(sk->sk_filter, fp);
rcu_read_unlock_bh();
fp = old_fp;
}
......
......@@ -247,11 +247,7 @@ int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
goto out;
}
/* It would be deadlock, if sock_queue_rcv_skb is used
with socket lock! We assume that users of this
function are lock free.
*/
err = sk_filter(sk, skb, 1);
err = sk_filter(sk, skb);
if (err)
goto out;
......@@ -278,7 +274,7 @@ int sk_receive_skb(struct sock *sk, struct sk_buff *skb)
{
int rc = NET_RX_SUCCESS;
if (sk_filter(sk, skb, 0))
if (sk_filter(sk, skb))
goto discard_and_relse;
skb->dev = NULL;
......@@ -606,15 +602,15 @@ set_rcvbuf:
break;
case SO_DETACH_FILTER:
spin_lock_bh(&sk->sk_lock.slock);
filter = sk->sk_filter;
rcu_read_lock_bh();
filter = rcu_dereference(sk->sk_filter);
if (filter) {
sk->sk_filter = NULL;
spin_unlock_bh(&sk->sk_lock.slock);
rcu_assign_pointer(sk->sk_filter, NULL);
sk_filter_release(sk, filter);
rcu_read_unlock_bh();
break;
}
spin_unlock_bh(&sk->sk_lock.slock);
rcu_read_unlock_bh();
ret = -ENONET;
break;
......@@ -884,10 +880,10 @@ void sk_free(struct sock *sk)
if (sk->sk_destruct)
sk->sk_destruct(sk);
filter = sk->sk_filter;
filter = rcu_dereference(sk->sk_filter);
if (filter) {
sk_filter_release(sk, filter);
sk->sk_filter = NULL;
rcu_assign_pointer(sk->sk_filter, NULL);
}
sock_disable_timestamp(sk);
......
......@@ -970,7 +970,7 @@ static int dccp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
if (skb->protocol == htons(ETH_P_IP))
return dccp_v4_do_rcv(sk, skb);
if (sk_filter(sk, skb, 0))
if (sk_filter(sk, skb))
goto discard;
/*
......
......@@ -586,7 +586,7 @@ static __inline__ int dn_queue_skb(struct sock *sk, struct sk_buff *skb, int sig
goto out;
}
err = sk_filter(sk, skb, 0);
err = sk_filter(sk, skb);
if (err)
goto out;
......
......@@ -1104,7 +1104,7 @@ process:
goto discard_and_relse;
nf_reset(skb);
if (sk_filter(sk, skb, 0))
if (sk_filter(sk, skb))
goto discard_and_relse;
skb->dev = NULL;
......
......@@ -1075,7 +1075,7 @@ static int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
if (skb->protocol == htons(ETH_P_IP))
return tcp_v4_do_rcv(sk, skb);
if (sk_filter(sk, skb, 0))
if (sk_filter(sk, skb))
goto discard;
/*
......@@ -1232,7 +1232,7 @@ process:
if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
goto discard_and_relse;
if (sk_filter(sk, skb, 0))
if (sk_filter(sk, skb))
goto discard_and_relse;
skb->dev = NULL;
......
......@@ -427,21 +427,24 @@ out_unlock:
}
#endif
static inline unsigned run_filter(struct sk_buff *skb, struct sock *sk, unsigned res)
static inline int run_filter(struct sk_buff *skb, struct sock *sk,
unsigned *snaplen)
{
struct sk_filter *filter;
int err = 0;
bh_lock_sock(sk);
filter = sk->sk_filter;
/*
* Our caller already checked that filter != NULL but we need to
* verify that under bh_lock_sock() to be safe
*/
if (likely(filter != NULL))
res = sk_run_filter(skb, filter->insns, filter->len);
bh_unlock_sock(sk);
rcu_read_lock_bh();
filter = rcu_dereference(sk->sk_filter);
if (filter != NULL) {
err = sk_run_filter(skb, filter->insns, filter->len);
if (!err)
err = -EPERM;
else if (*snaplen > err)
*snaplen = err;
}
rcu_read_unlock_bh();
return res;
return err;
}
/*
......@@ -491,13 +494,8 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev, struct packet
snaplen = skb->len;
if (sk->sk_filter) {
unsigned res = run_filter(skb, sk, snaplen);
if (res == 0)
goto drop_n_restore;
if (snaplen > res)
snaplen = res;
}
if (run_filter(skb, sk, &snaplen) < 0)
goto drop_n_restore;
if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
(unsigned)sk->sk_rcvbuf)
......@@ -593,13 +591,8 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, struct packe
snaplen = skb->len;
if (sk->sk_filter) {
unsigned res = run_filter(skb, sk, snaplen);
if (res == 0)
goto drop_n_restore;
if (snaplen > res)
snaplen = res;
}
if (run_filter(skb, sk, &snaplen) < 0)
goto drop_n_restore;
if (sk->sk_type == SOCK_DGRAM) {
macoff = netoff = TPACKET_ALIGN(TPACKET_HDRLEN) + 16;
......
......@@ -228,7 +228,7 @@ int sctp_rcv(struct sk_buff *skb)
goto discard_release;
nf_reset(skb);
if (sk_filter(sk, skb, 1))
if (sk_filter(sk, skb))
goto discard_release;
/* Create an SCTP packet structure. */
......
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