From dd4f10722aeb10f4f582948839f066bebe44e5fb Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 3 Mar 2017 21:01:02 -0800 Subject: net: fix socket refcounting in skb_complete_wifi_ack() TX skbs do not necessarily hold a reference on skb->sk->sk_refcnt By the time TX completion happens, sk_refcnt might be already 0. sock_hold()/sock_put() would then corrupt critical state, like sk_wmem_alloc. Fixes: bf7fa551e0ce ("mac80211: Resolve sk_refcnt/sk_wmem_alloc issue in wifi ack path") Signed-off-by: Eric Dumazet Cc: Alexander Duyck Cc: Johannes Berg Cc: Soheil Hassas Yeganeh Cc: Willem de Bruijn Acked-by: Soheil Hassas Yeganeh Signed-off-by: David S. Miller --- net/core/skbuff.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) (limited to 'net/core/skbuff.c') diff --git a/net/core/skbuff.c b/net/core/skbuff.c index f3557958e9bf..e2f37a560ec4 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3893,7 +3893,7 @@ void skb_complete_wifi_ack(struct sk_buff *skb, bool acked) { struct sock *sk = skb->sk; struct sock_exterr_skb *serr; - int err; + int err = 1; skb->wifi_acked_valid = 1; skb->wifi_acked = acked; @@ -3903,14 +3903,15 @@ void skb_complete_wifi_ack(struct sk_buff *skb, bool acked) serr->ee.ee_errno = ENOMSG; serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS; - /* take a reference to prevent skb_orphan() from freeing the socket */ - sock_hold(sk); - - err = sock_queue_err_skb(sk, skb); + /* Take a reference to prevent skb_orphan() from freeing the socket, + * but only if the socket refcount is not zero. + */ + if (likely(atomic_inc_not_zero(&sk->sk_refcnt))) { + err = sock_queue_err_skb(sk, skb); + sock_put(sk); + } if (err) kfree_skb(skb); - - sock_put(sk); } EXPORT_SYMBOL_GPL(skb_complete_wifi_ack); -- cgit v1.2.3 From 9ac25fc063751379cb77434fef9f3b088cd3e2f7 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 3 Mar 2017 21:01:03 -0800 Subject: net: fix socket refcounting in skb_complete_tx_timestamp() TX skbs do not necessarily hold a reference on skb->sk->sk_refcnt By the time TX completion happens, sk_refcnt might be already 0. sock_hold()/sock_put() would then corrupt critical state, like sk_wmem_alloc and lead to leaks or use after free. Fixes: 62bccb8cdb69 ("net-timestamp: Make the clone operation stand-alone from phy timestamping") Signed-off-by: Eric Dumazet Cc: Alexander Duyck Cc: Johannes Berg Cc: Soheil Hassas Yeganeh Cc: Willem de Bruijn Acked-by: Soheil Hassas Yeganeh Signed-off-by: David S. Miller --- net/core/skbuff.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) (limited to 'net/core/skbuff.c') diff --git a/net/core/skbuff.c b/net/core/skbuff.c index e2f37a560ec4..cd4ba8c6b609 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3828,13 +3828,14 @@ void skb_complete_tx_timestamp(struct sk_buff *skb, if (!skb_may_tx_timestamp(sk, false)) return; - /* take a reference to prevent skb_orphan() from freeing the socket */ - sock_hold(sk); - - *skb_hwtstamps(skb) = *hwtstamps; - __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND); - - sock_put(sk); + /* Take a reference to prevent skb_orphan() from freeing the socket, + * but only if the socket refcount is not zero. + */ + if (likely(atomic_inc_not_zero(&sk->sk_refcnt))) { + *skb_hwtstamps(skb) = *hwtstamps; + __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND); + sock_put(sk); + } } EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp); -- cgit v1.2.3 From 8605330aac5a5785630aec8f64378a54891937cc Mon Sep 17 00:00:00 2001 From: Soheil Hassas Yeganeh Date: Sat, 18 Mar 2017 17:02:59 -0400 Subject: tcp: fix SCM_TIMESTAMPING_OPT_STATS for normal skbs __sock_recv_timestamp can be called for both normal skbs (for receive timestamps) and for skbs on the error queue (for transmit timestamps). Commit 1c885808e456 (tcp: SOF_TIMESTAMPING_OPT_STATS option for SO_TIMESTAMPING) assumes any skb passed to __sock_recv_timestamp are from the error queue, containing OPT_STATS in the content of the skb. This results in accessing invalid memory or generating junk data. To fix this, set skb->pkt_type to PACKET_OUTGOING for packets on the error queue. This is safe because on the receive path on local sockets skb->pkt_type is never set to PACKET_OUTGOING. With that, copy OPT_STATS from a packet, only if its pkt_type is PACKET_OUTGOING. Fixes: 1c885808e456 ("tcp: SOF_TIMESTAMPING_OPT_STATS option for SO_TIMESTAMPING") Reported-by: JongHwan Kim Signed-off-by: Soheil Hassas Yeganeh Signed-off-by: Eric Dumazet Signed-off-by: Willem de Bruijn Signed-off-by: David S. Miller --- net/core/skbuff.c | 10 ++++++++++ net/socket.c | 13 ++++++++++++- 2 files changed, 22 insertions(+), 1 deletion(-) (limited to 'net/core/skbuff.c') diff --git a/net/core/skbuff.c b/net/core/skbuff.c index cd4ba8c6b609..b1fbd1958eb6 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3694,6 +3694,15 @@ static void sock_rmem_free(struct sk_buff *skb) atomic_sub(skb->truesize, &sk->sk_rmem_alloc); } +static void skb_set_err_queue(struct sk_buff *skb) +{ + /* pkt_type of skbs received on local sockets is never PACKET_OUTGOING. + * So, it is safe to (mis)use it to mark skbs on the error queue. + */ + skb->pkt_type = PACKET_OUTGOING; + BUILD_BUG_ON(PACKET_OUTGOING == 0); +} + /* * Note: We dont mem charge error packets (no sk_forward_alloc changes) */ @@ -3707,6 +3716,7 @@ int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb) skb->sk = sk; skb->destructor = sock_rmem_free; atomic_add(skb->truesize, &sk->sk_rmem_alloc); + skb_set_err_queue(skb); /* before exiting rcu section, make sure dst is refcounted */ skb_dst_force(skb); diff --git a/net/socket.c b/net/socket.c index e034fe4164be..692d6989d2c2 100644 --- a/net/socket.c +++ b/net/socket.c @@ -652,6 +652,16 @@ int kernel_sendmsg(struct socket *sock, struct msghdr *msg, } EXPORT_SYMBOL(kernel_sendmsg); +static bool skb_is_err_queue(const struct sk_buff *skb) +{ + /* pkt_type of skbs enqueued on the error queue are set to + * PACKET_OUTGOING in skb_set_err_queue(). This is only safe to do + * in recvmsg, since skbs received on a local socket will never + * have a pkt_type of PACKET_OUTGOING. + */ + return skb->pkt_type == PACKET_OUTGOING; +} + /* * called from sock_recv_timestamp() if sock_flag(sk, SOCK_RCVTSTAMP) */ @@ -695,7 +705,8 @@ void __sock_recv_timestamp(struct msghdr *msg, struct sock *sk, put_cmsg(msg, SOL_SOCKET, SCM_TIMESTAMPING, sizeof(tss), &tss); - if (skb->len && (sk->sk_tsflags & SOF_TIMESTAMPING_OPT_STATS)) + if (skb_is_err_queue(skb) && skb->len && + (sk->sk_tsflags & SOF_TIMESTAMPING_OPT_STATS)) put_cmsg(msg, SOL_SOCKET, SCM_TIMESTAMPING_OPT_STATS, skb->len, skb->data); } -- cgit v1.2.3 From 4ef1b2869447411ad3ef91ad7d4891a83c1a509a Mon Sep 17 00:00:00 2001 From: Soheil Hassas Yeganeh Date: Sat, 18 Mar 2017 17:03:00 -0400 Subject: tcp: mark skbs with SCM_TIMESTAMPING_OPT_STATS SOF_TIMESTAMPING_OPT_STATS can be enabled and disabled while packets are collected on the error queue. So, checking SOF_TIMESTAMPING_OPT_STATS in sk->sk_tsflags is not enough to safely assume that the skb contains OPT_STATS data. Add a bit in sock_exterr_skb to indicate whether the skb contains opt_stats data. Fixes: 1c885808e456 ("tcp: SOF_TIMESTAMPING_OPT_STATS option for SO_TIMESTAMPING") Reported-by: JongHwan Kim Signed-off-by: Soheil Hassas Yeganeh Signed-off-by: Eric Dumazet Signed-off-by: Willem de Bruijn Signed-off-by: David S. Miller --- include/linux/errqueue.h | 2 ++ net/core/skbuff.c | 17 +++++++++++------ net/socket.c | 2 +- 3 files changed, 14 insertions(+), 7 deletions(-) (limited to 'net/core/skbuff.c') diff --git a/include/linux/errqueue.h b/include/linux/errqueue.h index 9ca23fcfb5d7..6fdfc884fdeb 100644 --- a/include/linux/errqueue.h +++ b/include/linux/errqueue.h @@ -20,6 +20,8 @@ struct sock_exterr_skb { struct sock_extended_err ee; u16 addr_offset; __be16 port; + u8 opt_stats:1, + unused:7; }; #endif diff --git a/net/core/skbuff.c b/net/core/skbuff.c index b1fbd1958eb6..9f781092fda9 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3793,16 +3793,20 @@ EXPORT_SYMBOL(skb_clone_sk); static void __skb_complete_tx_timestamp(struct sk_buff *skb, struct sock *sk, - int tstype) + int tstype, + bool opt_stats) { struct sock_exterr_skb *serr; int err; + BUILD_BUG_ON(sizeof(struct sock_exterr_skb) > sizeof(skb->cb)); + serr = SKB_EXT_ERR(skb); memset(serr, 0, sizeof(*serr)); serr->ee.ee_errno = ENOMSG; serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING; serr->ee.ee_info = tstype; + serr->opt_stats = opt_stats; if (sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID) { serr->ee.ee_data = skb_shinfo(skb)->tskey; if (sk->sk_protocol == IPPROTO_TCP && @@ -3843,7 +3847,7 @@ void skb_complete_tx_timestamp(struct sk_buff *skb, */ if (likely(atomic_inc_not_zero(&sk->sk_refcnt))) { *skb_hwtstamps(skb) = *hwtstamps; - __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND); + __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND, false); sock_put(sk); } } @@ -3854,7 +3858,7 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb, struct sock *sk, int tstype) { struct sk_buff *skb; - bool tsonly; + bool tsonly, opt_stats = false; if (!sk) return; @@ -3867,9 +3871,10 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb, #ifdef CONFIG_INET if ((sk->sk_tsflags & SOF_TIMESTAMPING_OPT_STATS) && sk->sk_protocol == IPPROTO_TCP && - sk->sk_type == SOCK_STREAM) + sk->sk_type == SOCK_STREAM) { skb = tcp_get_timestamping_opt_stats(sk); - else + opt_stats = true; + } else #endif skb = alloc_skb(0, GFP_ATOMIC); } else { @@ -3888,7 +3893,7 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb, else skb->tstamp = ktime_get_real(); - __skb_complete_tx_timestamp(skb, sk, tstype); + __skb_complete_tx_timestamp(skb, sk, tstype, opt_stats); } EXPORT_SYMBOL_GPL(__skb_tstamp_tx); diff --git a/net/socket.c b/net/socket.c index 692d6989d2c2..985ef06792d6 100644 --- a/net/socket.c +++ b/net/socket.c @@ -706,7 +706,7 @@ void __sock_recv_timestamp(struct msghdr *msg, struct sock *sk, SCM_TIMESTAMPING, sizeof(tss), &tss); if (skb_is_err_queue(skb) && skb->len && - (sk->sk_tsflags & SOF_TIMESTAMPING_OPT_STATS)) + SKB_EXT_ERR(skb)->opt_stats) put_cmsg(msg, SOL_SOCKET, SCM_TIMESTAMPING_OPT_STATS, skb->len, skb->data); } -- cgit v1.2.3