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CVE-2012-3412 sfc: potential rDOS through TCP MSS option (rhbz 844714 845558)

This commit is contained in:
Josh Boyer 2012-08-03 09:30:37 -04:00
parent 5613df668e
commit d1e5565689
4 changed files with 364 additions and 1 deletions
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15
kernel.spec
View File

@ -54,7 +54,7 @@ Summary: The Linux kernel
# For non-released -rc kernels, this will be appended after the rcX and
# gitX tags, so a 3 here would become part of release "0.rcX.gitX.3"
#
%global baserelease 1
%global baserelease 2
%global fedora_build %{baserelease}
# base_sublevel is the kernel version we're starting with and patching
@ -716,6 +716,11 @@ Patch22060: CPU-hotplug-cpusets-suspend-Dont-modify-cpusets-during.patch
#rhbz 820039 843554
Patch22061: rds-set-correct-msg_namelen.patch
#rhbz 845558 844714
Patch22070: net-Allow-driver-to-limit-number-of-GSO-segments-per-skb.patch
Patch22071: sfc-Fix-maximum-number-of-TSO-segments-and-minimum-TX-queue-size.patch
Patch22072: tcp-Apply-device-TSO-segment-limit-earlier.patch
# END OF PATCH DEFINITIONS
%endif
@ -1337,6 +1342,11 @@ ApplyPatch CPU-hotplug-cpusets-suspend-Dont-modify-cpusets-during.patch
#rhbz 820039 843554
ApplyPatch rds-set-correct-msg_namelen.patch
#rhbz 845558 844714
ApplyPatch net-Allow-driver-to-limit-number-of-GSO-segments-per-skb.patch
ApplyPatch sfc-Fix-maximum-number-of-TSO-segments-and-minimum-TX-queue-size.patch
ApplyPatch tcp-Apply-device-TSO-segment-limit-earlier.patch
# END OF PATCH APPLICATIONS
%endif
@ -2035,6 +2045,9 @@ fi
# and build.
%changelog
* Fri Aug 03 2012 Josh Boyer <jwboyer@redhat.com>
- CVE-2012-3412 sfc: potential rDOS through TCP MSS option (rhbz 844714 845558)
* Mon Jul 30 2012 Dave Jones <davej@redhat.com> 3.4.7-1
- Linux 3.4.7

70
net-Allow-driver-to-limit-number-of-GSO-segments-per-skb.patch Normal file
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@ -0,0 +1,70 @@
From 30b678d844af3305cda5953467005cebb5d7b687 Mon Sep 17 00:00:00 2001
From: Ben Hutchings <bhutchings@solarflare.com>
Date: Mon, 30 Jul 2012 15:57:00 +0000
Subject: [PATCH] net: Allow driver to limit number of GSO segments per skb
A peer (or local user) may cause TCP to use a nominal MSS of as little
as 88 (actual MSS of 76 with timestamps). Given that we have a
sufficiently prodigious local sender and the peer ACKs quickly enough,
it is nevertheless possible to grow the window for such a connection
to the point that we will try to send just under 64K at once. This
results in a single skb that expands to 861 segments.
In some drivers with TSO support, such an skb will require hundreds of
DMA descriptors; a substantial fraction of a TX ring or even more than
a full ring. The TX queue selected for the skb may stall and trigger
the TX watchdog repeatedly (since the problem skb will be retried
after the TX reset). This particularly affects sfc, for which the
issue is designated as CVE-2012-3412.
Therefore:
1. Add the field net_device::gso_max_segs holding the device-specific
limit.
2. In netif_skb_features(), if the number of segments is too high then
mask out GSO features to force fall back to software GSO.
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
include/linux/netdevice.h | 2 ++
net/core/dev.c | 4 ++++
2 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index eb06e58..a9db4f3 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1300,6 +1300,8 @@ struct net_device {
/* for setting kernel sock attribute on TCP connection setup */
#define GSO_MAX_SIZE 65536
unsigned int gso_max_size;
+#define GSO_MAX_SEGS 65535
+ u16 gso_max_segs;
#ifdef CONFIG_DCB
/* Data Center Bridging netlink ops */
diff --git a/net/core/dev.c b/net/core/dev.c
index 0cb3fe8..f91abf8 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2134,6 +2134,9 @@ netdev_features_t netif_skb_features(struct sk_buff *skb)
__be16 protocol = skb->protocol;
netdev_features_t features = skb->dev->features;
+ if (skb_shinfo(skb)->gso_segs > skb->dev->gso_max_segs)
+ features &= ~NETIF_F_GSO_MASK;
+
if (protocol == htons(ETH_P_8021Q)) {
struct vlan_ethhdr *veh = (struct vlan_ethhdr *)skb->data;
protocol = veh->h_vlan_encapsulated_proto;
@@ -5986,6 +5989,7 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
dev_net_set(dev, &init_net);
dev->gso_max_size = GSO_MAX_SIZE;
+ dev->gso_max_segs = GSO_MAX_SEGS;
INIT_LIST_HEAD(&dev->napi_list);
INIT_LIST_HEAD(&dev->unreg_list);
--
1.7.7.6

156
sfc-Fix-maximum-number-of-TSO-segments-and-minimum-TX-queue-size.patch Normal file
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@ -0,0 +1,156 @@
From 7e6d06f0de3f74ca929441add094518ae332257c Mon Sep 17 00:00:00 2001
From: Ben Hutchings <bhutchings@solarflare.com>
Date: Mon, 30 Jul 2012 15:57:44 +0000
Subject: [PATCH] sfc: Fix maximum number of TSO segments and minimum TX queue
size
Currently an skb requiring TSO may not fit within a minimum-size TX
queue. The TX queue selected for the skb may stall and trigger the TX
watchdog repeatedly (since the problem skb will be retried after the
TX reset). This issue is designated as CVE-2012-3412.
Set the maximum number of TSO segments for our devices to 100. This
should make no difference to behaviour unless the actual MSS is less
than about 700. Increase the minimum TX queue size accordingly to
allow for 2 worst-case skbs, so that there will definitely be space
to add an skb after we wake a queue.
To avoid invalidating existing configurations, change
efx_ethtool_set_ringparam() to fix up values that are too small rather
than returning -EINVAL.
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
drivers/net/ethernet/sfc/efx.c | 6 ++++++
drivers/net/ethernet/sfc/efx.h | 14 ++++++++++----
drivers/net/ethernet/sfc/ethtool.c | 16 +++++++++++-----
drivers/net/ethernet/sfc/tx.c | 19 +++++++++++++++++++
4 files changed, 46 insertions(+), 9 deletions(-)
diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index 70554a1..65a8d49 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -1503,6 +1503,11 @@ static int efx_probe_all(struct efx_nic *efx)
goto fail2;
}
+ BUILD_BUG_ON(EFX_DEFAULT_DMAQ_SIZE < EFX_RXQ_MIN_ENT);
+ if (WARN_ON(EFX_DEFAULT_DMAQ_SIZE < EFX_TXQ_MIN_ENT(efx))) {
+ rc = -EINVAL;
+ goto fail3;
+ }
efx->rxq_entries = efx->txq_entries = EFX_DEFAULT_DMAQ_SIZE;
rc = efx_probe_filters(efx);
@@ -2070,6 +2075,7 @@ static int efx_register_netdev(struct efx_nic *efx)
net_dev->irq = efx->pci_dev->irq;
net_dev->netdev_ops = &efx_netdev_ops;
SET_ETHTOOL_OPS(net_dev, &efx_ethtool_ops);
+ net_dev->gso_max_segs = EFX_TSO_MAX_SEGS;
rtnl_lock();
diff --git a/drivers/net/ethernet/sfc/efx.h b/drivers/net/ethernet/sfc/efx.h
index be8f915..70755c9 100644
--- a/drivers/net/ethernet/sfc/efx.h
+++ b/drivers/net/ethernet/sfc/efx.h
@@ -30,6 +30,7 @@ extern netdev_tx_t
efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb);
extern void efx_xmit_done(struct efx_tx_queue *tx_queue, unsigned int index);
extern int efx_setup_tc(struct net_device *net_dev, u8 num_tc);
+extern unsigned int efx_tx_max_skb_descs(struct efx_nic *efx);
/* RX */
extern int efx_probe_rx_queue(struct efx_rx_queue *rx_queue);
@@ -52,10 +53,15 @@ extern void efx_schedule_slow_fill(struct efx_rx_queue *rx_queue);
#define EFX_MAX_EVQ_SIZE 16384UL
#define EFX_MIN_EVQ_SIZE 512UL
-/* The smallest [rt]xq_entries that the driver supports. Callers of
- * efx_wake_queue() assume that they can subsequently send at least one
- * skb. Falcon/A1 may require up to three descriptors per skb_frag. */
-#define EFX_MIN_RING_SIZE (roundup_pow_of_two(2 * 3 * MAX_SKB_FRAGS))
+/* Maximum number of TCP segments we support for soft-TSO */
+#define EFX_TSO_MAX_SEGS 100
+
+/* The smallest [rt]xq_entries that the driver supports. RX minimum
+ * is a bit arbitrary. For TX, we must have space for at least 2
+ * TSO skbs.
+ */
+#define EFX_RXQ_MIN_ENT 128U
+#define EFX_TXQ_MIN_ENT(efx) (2 * efx_tx_max_skb_descs(efx))
/* Filters */
extern int efx_probe_filters(struct efx_nic *efx);
diff --git a/drivers/net/ethernet/sfc/ethtool.c b/drivers/net/ethernet/sfc/ethtool.c
index 10536f9..8cba2df 100644
--- a/drivers/net/ethernet/sfc/ethtool.c
+++ b/drivers/net/ethernet/sfc/ethtool.c
@@ -680,21 +680,27 @@ static int efx_ethtool_set_ringparam(struct net_device *net_dev,
struct ethtool_ringparam *ring)
{
struct efx_nic *efx = netdev_priv(net_dev);
+ u32 txq_entries;
if (ring->rx_mini_pending || ring->rx_jumbo_pending ||
ring->rx_pending > EFX_MAX_DMAQ_SIZE ||
ring->tx_pending > EFX_MAX_DMAQ_SIZE)
return -EINVAL;
- if (ring->rx_pending < EFX_MIN_RING_SIZE ||
- ring->tx_pending < EFX_MIN_RING_SIZE) {
+ if (ring->rx_pending < EFX_RXQ_MIN_ENT) {
netif_err(efx, drv, efx->net_dev,
- "TX and RX queues cannot be smaller than %ld\n",
- EFX_MIN_RING_SIZE);
+ "RX queues cannot be smaller than %u\n",
+ EFX_RXQ_MIN_ENT);
return -EINVAL;
}
- return efx_realloc_channels(efx, ring->rx_pending, ring->tx_pending);
+ txq_entries = max(ring->tx_pending, EFX_TXQ_MIN_ENT(efx));
+ if (txq_entries != ring->tx_pending)
+ netif_warn(efx, drv, efx->net_dev,
+ "increasing TX queue size to minimum of %u\n",
+ txq_entries);
+
+ return efx_realloc_channels(efx, ring->rx_pending, txq_entries);
}
static int efx_ethtool_set_pauseparam(struct net_device *net_dev,
diff --git a/drivers/net/ethernet/sfc/tx.c b/drivers/net/ethernet/sfc/tx.c
index 9b225a7..1871343 100644
--- a/drivers/net/ethernet/sfc/tx.c
+++ b/drivers/net/ethernet/sfc/tx.c
@@ -119,6 +119,25 @@ efx_max_tx_len(struct efx_nic *efx, dma_addr_t dma_addr)
return len;
}
+unsigned int efx_tx_max_skb_descs(struct efx_nic *efx)
+{
+ /* Header and payload descriptor for each output segment, plus
+ * one for every input fragment boundary within a segment
+ */
+ unsigned int max_descs = EFX_TSO_MAX_SEGS * 2 + MAX_SKB_FRAGS;
+
+ /* Possibly one more per segment for the alignment workaround */
+ if (EFX_WORKAROUND_5391(efx))
+ max_descs += EFX_TSO_MAX_SEGS;
+
+ /* Possibly more for PCIe page boundaries within input fragments */
+ if (PAGE_SIZE > EFX_PAGE_SIZE)
+ max_descs += max_t(unsigned int, MAX_SKB_FRAGS,
+ DIV_ROUND_UP(GSO_MAX_SIZE, EFX_PAGE_SIZE));
+
+ return max_descs;
+}
+
/*
* Add a socket buffer to a TX queue
*
--
1.7.7.6

124
tcp-Apply-device-TSO-segment-limit-earlier.patch Normal file
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@ -0,0 +1,124 @@
From 1485348d2424e1131ea42efc033cbd9366462b01 Mon Sep 17 00:00:00 2001
From: Ben Hutchings <bhutchings@solarflare.com>
Date: Mon, 30 Jul 2012 16:11:42 +0000
Subject: [PATCH] tcp: Apply device TSO segment limit earlier
Cache the device gso_max_segs in sock::sk_gso_max_segs and use it to
limit the size of TSO skbs. This avoids the need to fall back to
software GSO for local TCP senders.
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
include/net/sock.h | 2 ++
net/core/sock.c | 1 +
net/ipv4/tcp.c | 4 +++-
net/ipv4/tcp_cong.c | 3 ++-
net/ipv4/tcp_output.c | 21 ++++++++++++---------
5 files changed, 20 insertions(+), 11 deletions(-)
--- linux-3.4.noarch.orig/include/net/sock.h
+++ linux-3.4.noarch/include/net/sock.h
@@ -216,6 +216,7 @@ struct cg_proto;
* @sk_route_nocaps: forbidden route capabilities (e.g NETIF_F_GSO_MASK)
* @sk_gso_type: GSO type (e.g. %SKB_GSO_TCPV4)
* @sk_gso_max_size: Maximum GSO segment size to build
+ * @sk_gso_max_segs: Maximum number of GSO segments
* @sk_lingertime: %SO_LINGER l_linger setting
* @sk_backlog: always used with the per-socket spinlock held
* @sk_callback_lock: used with the callbacks in the end of this struct
@@ -335,6 +336,7 @@ struct sock {
netdev_features_t sk_route_nocaps;
int sk_gso_type;
unsigned int sk_gso_max_size;
+ u16 sk_gso_max_segs;
int sk_rcvlowat;
unsigned long sk_lingertime;
struct sk_buff_head sk_error_queue;
--- linux-3.4.noarch.orig/net/core/sock.c
+++ linux-3.4.noarch/net/core/sock.c
@@ -1411,6 +1411,7 @@ void sk_setup_caps(struct sock *sk, stru
} else {
sk->sk_route_caps |= NETIF_F_SG | NETIF_F_HW_CSUM;
sk->sk_gso_max_size = dst->dev->gso_max_size;
+ sk->sk_gso_max_segs = dst->dev->gso_max_segs;
}
}
}
--- linux-3.4.noarch.orig/net/ipv4/tcp.c
+++ linux-3.4.noarch/net/ipv4/tcp.c
@@ -740,7 +740,9 @@ static unsigned int tcp_xmit_size_goal(s
old_size_goal + mss_now > xmit_size_goal)) {
xmit_size_goal = old_size_goal;
} else {
- tp->xmit_size_goal_segs = xmit_size_goal / mss_now;
+ tp->xmit_size_goal_segs =
+ min_t(u16, xmit_size_goal / mss_now,
+ sk->sk_gso_max_segs);
xmit_size_goal = tp->xmit_size_goal_segs * mss_now;
}
}
--- linux-3.4.noarch.orig/net/ipv4/tcp_cong.c
+++ linux-3.4.noarch/net/ipv4/tcp_cong.c
@@ -291,7 +291,8 @@ int tcp_is_cwnd_limited(const struct soc
left = tp->snd_cwnd - in_flight;
if (sk_can_gso(sk) &&
left * sysctl_tcp_tso_win_divisor < tp->snd_cwnd &&
- left * tp->mss_cache < sk->sk_gso_max_size)
+ left * tp->mss_cache < sk->sk_gso_max_size &&
+ left < sk->sk_gso_max_segs)
return 1;
return left <= tcp_max_tso_deferred_mss(tp);
}
--- linux-3.4.noarch.orig/net/ipv4/tcp_output.c
+++ linux-3.4.noarch/net/ipv4/tcp_output.c
@@ -1318,21 +1318,21 @@ static void tcp_cwnd_validate(struct soc
* when we would be allowed to send the split-due-to-Nagle skb fully.
*/
static unsigned int tcp_mss_split_point(const struct sock *sk, const struct sk_buff *skb,
- unsigned int mss_now, unsigned int cwnd)
+ unsigned int mss_now, unsigned int max_segs)
{
const struct tcp_sock *tp = tcp_sk(sk);
- u32 needed, window, cwnd_len;
+ u32 needed, window, max_len;
window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq;
- cwnd_len = mss_now * cwnd;
+ max_len = mss_now * max_segs;
- if (likely(cwnd_len <= window && skb != tcp_write_queue_tail(sk)))
- return cwnd_len;
+ if (likely(max_len <= window && skb != tcp_write_queue_tail(sk)))
+ return max_len;
needed = min(skb->len, window);
- if (cwnd_len <= needed)
- return cwnd_len;
+ if (max_len <= needed)
+ return max_len;
return needed - needed % mss_now;
}
@@ -1560,7 +1560,8 @@ static int tcp_tso_should_defer(struct s
limit = min(send_win, cong_win);
/* If a full-sized TSO skb can be sent, do it. */
- if (limit >= sk->sk_gso_max_size)
+ if (limit >= min_t(unsigned int, sk->sk_gso_max_size,
+ sk->sk_gso_max_segs * tp->mss_cache))
goto send_now;
/* Middle in queue won't get any more data, full sendable already? */
@@ -1786,7 +1787,9 @@ static int tcp_write_xmit(struct sock *s
limit = mss_now;
if (tso_segs > 1 && !tcp_urg_mode(tp))
limit = tcp_mss_split_point(sk, skb, mss_now,
- cwnd_quota);
+ min_t(unsigned int,
+ cwnd_quota,
+ sk->sk_gso_max_segs));
if (skb->len > limit &&
unlikely(tso_fragment(sk, skb, limit, mss_now, gfp)))