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CVE-2013-0216/0127 xen: netback DoS via malicious guest ring (rhbz 910886)

This commit is contained in:
Josh Boyer 2013-02-14 09:12:20 -05:00
parent 2fa62b2c11
commit d4c9a720d9
5 changed files with 475 additions and 1 deletions
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17
kernel.spec
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@ -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 101
%global baserelease 102
%global fedora_build %{baserelease}
# base_sublevel is the kernel version we're starting with and patching
@ -760,6 +760,12 @@ Patch21246: rtlwifi-Fix-scheduling-while-atomic-bug.patch
#rhbz 892811
Patch21247: ath9k_rx_dma_stop_check.patch
#rhbz 910886 CVE-2013-0216/CVE-2013-0217
Patch21250: xen-netback-shutdown-the-ring-if-it-contains-garbage.patch
Patch21251: xen-netback-don-t-leak-pages-on-failure-in-xen_netbk_tx_check_gop.patch
Patch21252: xen-netback-free-already-allocated-memory-on-failure-in-xen_netbk_get_requests.patch
Patch21253: netback-correct-netbk_tx_err-to-handle-wrap-around.patch
# END OF PATCH DEFINITIONS
%endif
@ -1469,6 +1475,12 @@ ApplyPatch rtlwifi-Fix-scheduling-while-atomic-bug.patch
#rhbz 892811
ApplyPatch ath9k_rx_dma_stop_check.patch
#rhbz 910886 CVE-2013-0216/CVE-2013-0217
ApplyPatch xen-netback-shutdown-the-ring-if-it-contains-garbage.patch
ApplyPatch xen-netback-don-t-leak-pages-on-failure-in-xen_netbk_tx_check_gop.patch
ApplyPatch xen-netback-free-already-allocated-memory-on-failure-in-xen_netbk_get_requests.patch
ApplyPatch netback-correct-netbk_tx_err-to-handle-wrap-around.patch
# END OF PATCH APPLICATIONS
%endif
@ -2324,6 +2336,9 @@ fi
# '-' | |
# '-'
%changelog
* Thu Feb 14 2013 Josh Boyer <jwboyer@redhat.com>
- CVE-2013-0216/0127 xen: netback DoS via malicious guest ring (rhbz 910886)
* Mon Feb 11 2013 Justin M. Forbes <jforbes@redhat.com> - 3.7.7-101
- Linux v3.7.7

29
netback-correct-netbk_tx_err-to-handle-wrap-around.patch Normal file
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@ -0,0 +1,29 @@
From d5b2f3542a1f9c7b5092816b87db08e9f08f1551 Mon Sep 17 00:00:00 2001
From: Ian Campbell <Ian.Campbell@citrix.com>
Date: Wed, 6 Feb 2013 23:41:38 +0000
Subject: netback: correct netbk_tx_err to handle wrap around.
From: Ian Campbell <Ian.Campbell@citrix.com>
[ Upstream commit b9149729ebdcfce63f853aa54a404c6a8f6ebbf3 ]
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Jan Beulich <JBeulich@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/xen-netback/netback.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -880,7 +880,7 @@ static void netbk_tx_err(struct xenvif *
do {
make_tx_response(vif, txp, XEN_NETIF_RSP_ERROR);
- if (cons >= end)
+ if (cons == end)
break;
txp = RING_GET_REQUEST(&vif->tx, cons++);
} while (1);

134
xen-netback-don-t-leak-pages-on-failure-in-xen_netbk_tx_check_gop.patch Normal file
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@ -0,0 +1,134 @@
From 10948f5aa9992de84e022e218b494586fe92d547 Mon Sep 17 00:00:00 2001
From: Matthew Daley <mattjd@gmail.com>
Date: Wed, 6 Feb 2013 23:41:36 +0000
Subject: xen/netback: don't leak pages on failure in xen_netbk_tx_check_gop.
From: Matthew Daley <mattjd@gmail.com>
[ Upstream commit 7d5145d8eb2b9791533ffe4dc003b129b9696c48 ]
Signed-off-by: Matthew Daley <mattjd@gmail.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Jan Beulich <JBeulich@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/xen-netback/netback.c | 38 +++++++++++++-------------------------
1 file changed, 13 insertions(+), 25 deletions(-)
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -147,7 +147,8 @@ void xen_netbk_remove_xenvif(struct xenv
atomic_dec(&netbk->netfront_count);
}
-static void xen_netbk_idx_release(struct xen_netbk *netbk, u16 pending_idx);
+static void xen_netbk_idx_release(struct xen_netbk *netbk, u16 pending_idx,
+ u8 status);
static void make_tx_response(struct xenvif *vif,
struct xen_netif_tx_request *txp,
s8 st);
@@ -1007,30 +1008,20 @@ static int xen_netbk_tx_check_gop(struct
{
struct gnttab_copy *gop = *gopp;
u16 pending_idx = *((u16 *)skb->data);
- struct pending_tx_info *pending_tx_info = netbk->pending_tx_info;
- struct xenvif *vif = pending_tx_info[pending_idx].vif;
- struct xen_netif_tx_request *txp;
struct skb_shared_info *shinfo = skb_shinfo(skb);
int nr_frags = shinfo->nr_frags;
int i, err, start;
/* Check status of header. */
err = gop->status;
- if (unlikely(err)) {
- pending_ring_idx_t index;
- index = pending_index(netbk->pending_prod++);
- txp = &pending_tx_info[pending_idx].req;
- make_tx_response(vif, txp, XEN_NETIF_RSP_ERROR);
- netbk->pending_ring[index] = pending_idx;
- xenvif_put(vif);
- }
+ if (unlikely(err))
+ xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_ERROR);
/* Skip first skb fragment if it is on same page as header fragment. */
start = (frag_get_pending_idx(&shinfo->frags[0]) == pending_idx);
for (i = start; i < nr_frags; i++) {
int j, newerr;
- pending_ring_idx_t index;
pending_idx = frag_get_pending_idx(&shinfo->frags[i]);
@@ -1039,16 +1030,12 @@ static int xen_netbk_tx_check_gop(struct
if (likely(!newerr)) {
/* Had a previous error? Invalidate this fragment. */
if (unlikely(err))
- xen_netbk_idx_release(netbk, pending_idx);
+ xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
continue;
}
/* Error on this fragment: respond to client with an error. */
- txp = &netbk->pending_tx_info[pending_idx].req;
- make_tx_response(vif, txp, XEN_NETIF_RSP_ERROR);
- index = pending_index(netbk->pending_prod++);
- netbk->pending_ring[index] = pending_idx;
- xenvif_put(vif);
+ xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_ERROR);
/* Not the first error? Preceding frags already invalidated. */
if (err)
@@ -1056,10 +1043,10 @@ static int xen_netbk_tx_check_gop(struct
/* First error: invalidate header and preceding fragments. */
pending_idx = *((u16 *)skb->data);
- xen_netbk_idx_release(netbk, pending_idx);
+ xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
for (j = start; j < i; j++) {
pending_idx = frag_get_pending_idx(&shinfo->frags[j]);
- xen_netbk_idx_release(netbk, pending_idx);
+ xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
}
/* Remember the error: invalidate all subsequent fragments. */
@@ -1093,7 +1080,7 @@ static void xen_netbk_fill_frags(struct
/* Take an extra reference to offset xen_netbk_idx_release */
get_page(netbk->mmap_pages[pending_idx]);
- xen_netbk_idx_release(netbk, pending_idx);
+ xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
}
}
@@ -1476,7 +1463,7 @@ static void xen_netbk_tx_submit(struct x
txp->size -= data_len;
} else {
/* Schedule a response immediately. */
- xen_netbk_idx_release(netbk, pending_idx);
+ xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
}
if (txp->flags & XEN_NETTXF_csum_blank)
@@ -1528,7 +1515,8 @@ static void xen_netbk_tx_action(struct x
xen_netbk_tx_submit(netbk);
}
-static void xen_netbk_idx_release(struct xen_netbk *netbk, u16 pending_idx)
+static void xen_netbk_idx_release(struct xen_netbk *netbk, u16 pending_idx,
+ u8 status)
{
struct xenvif *vif;
struct pending_tx_info *pending_tx_info;
@@ -1542,7 +1530,7 @@ static void xen_netbk_idx_release(struct
vif = pending_tx_info->vif;
- make_tx_response(vif, &pending_tx_info->req, XEN_NETIF_RSP_OKAY);
+ make_tx_response(vif, &pending_tx_info->req, status);
index = pending_index(netbk->pending_prod++);
netbk->pending_ring[index] = pending_idx;

46
xen-netback-free-already-allocated-memory-on-failure-in-xen_netbk_get_requests.patch Normal file
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@ -0,0 +1,46 @@
From 2e0b7c1781a94640566dccf9d7441d500fa69e40 Mon Sep 17 00:00:00 2001
From: Ian Campbell <Ian.Campbell@citrix.com>
Date: Wed, 6 Feb 2013 23:41:37 +0000
Subject: xen/netback: free already allocated memory on failure in xen_netbk_get_requests
From: Ian Campbell <Ian.Campbell@citrix.com>
[ Upstream commit 4cc7c1cb7b11b6f3515bd9075527576a1eecc4aa ]
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/xen-netback/netback.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -978,7 +978,7 @@ static struct gnttab_copy *xen_netbk_get
pending_idx = netbk->pending_ring[index];
page = xen_netbk_alloc_page(netbk, skb, pending_idx);
if (!page)
- return NULL;
+ goto err;
gop->source.u.ref = txp->gref;
gop->source.domid = vif->domid;
@@ -1000,6 +1000,17 @@ static struct gnttab_copy *xen_netbk_get
}
return gop;
+err:
+ /* Unwind, freeing all pages and sending error responses. */
+ while (i-- > start) {
+ xen_netbk_idx_release(netbk, frag_get_pending_idx(&frags[i]),
+ XEN_NETIF_RSP_ERROR);
+ }
+ /* The head too, if necessary. */
+ if (start)
+ xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_ERROR);
+
+ return NULL;
}
static int xen_netbk_tx_check_gop(struct xen_netbk *netbk,

250
xen-netback-shutdown-the-ring-if-it-contains-garbage.patch Normal file
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@ -0,0 +1,250 @@
From 5ef9a447aa4e6a1da43a04b98befa5643c806c1b Mon Sep 17 00:00:00 2001
From: Ian Campbell <Ian.Campbell@citrix.com>
Date: Wed, 6 Feb 2013 23:41:35 +0000
Subject: xen/netback: shutdown the ring if it contains garbage.
From: Ian Campbell <Ian.Campbell@citrix.com>
[ Upstream commit 48856286b64e4b66ec62b94e504d0b29c1ade664 ]
A buggy or malicious frontend should not be able to confuse netback.
If we spot anything which is not as it should be then shutdown the
device and don't try to continue with the ring in a potentially
hostile state. Well behaved and non-hostile frontends will not be
penalised.
As well as making the existing checks for such errors fatal also add a
new check that ensures that there isn't an insane number of requests
on the ring (i.e. more than would fit in the ring). If the ring
contains garbage then previously is was possible to loop over this
insane number, getting an error each time and therefore not generating
any more pending requests and therefore not exiting the loop in
xen_netbk_tx_build_gops for an externded period.
Also turn various netdev_dbg calls which no precipitate a fatal error
into netdev_err, they are rate limited because the device is shutdown
afterwards.
This fixes at least one known DoS/softlockup of the backend domain.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Jan Beulich <JBeulich@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/xen-netback/common.h | 3 +
drivers/net/xen-netback/interface.c | 23 ++++++++-----
drivers/net/xen-netback/netback.c | 62 ++++++++++++++++++++++++++----------
3 files changed, 62 insertions(+), 26 deletions(-)
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -151,6 +151,9 @@ void xen_netbk_queue_tx_skb(struct xenvi
/* Notify xenvif that ring now has space to send an skb to the frontend */
void xenvif_notify_tx_completion(struct xenvif *vif);
+/* Prevent the device from generating any further traffic. */
+void xenvif_carrier_off(struct xenvif *vif);
+
/* Returns number of ring slots required to send an skb to the frontend */
unsigned int xen_netbk_count_skb_slots(struct xenvif *vif, struct sk_buff *skb);
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -343,17 +343,22 @@ err:
return err;
}
-void xenvif_disconnect(struct xenvif *vif)
+void xenvif_carrier_off(struct xenvif *vif)
{
struct net_device *dev = vif->dev;
- if (netif_carrier_ok(dev)) {
- rtnl_lock();
- netif_carrier_off(dev); /* discard queued packets */
- if (netif_running(dev))
- xenvif_down(vif);
- rtnl_unlock();
- xenvif_put(vif);
- }
+
+ rtnl_lock();
+ netif_carrier_off(dev); /* discard queued packets */
+ if (netif_running(dev))
+ xenvif_down(vif);
+ rtnl_unlock();
+ xenvif_put(vif);
+}
+
+void xenvif_disconnect(struct xenvif *vif)
+{
+ if (netif_carrier_ok(vif->dev))
+ xenvif_carrier_off(vif);
atomic_dec(&vif->refcnt);
wait_event(vif->waiting_to_free, atomic_read(&vif->refcnt) == 0);
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -888,6 +888,13 @@ static void netbk_tx_err(struct xenvif *
xenvif_put(vif);
}
+static void netbk_fatal_tx_err(struct xenvif *vif)
+{
+ netdev_err(vif->dev, "fatal error; disabling device\n");
+ xenvif_carrier_off(vif);
+ xenvif_put(vif);
+}
+
static int netbk_count_requests(struct xenvif *vif,
struct xen_netif_tx_request *first,
struct xen_netif_tx_request *txp,
@@ -901,19 +908,22 @@ static int netbk_count_requests(struct x
do {
if (frags >= work_to_do) {
- netdev_dbg(vif->dev, "Need more frags\n");
+ netdev_err(vif->dev, "Need more frags\n");
+ netbk_fatal_tx_err(vif);
return -frags;
}
if (unlikely(frags >= MAX_SKB_FRAGS)) {
- netdev_dbg(vif->dev, "Too many frags\n");
+ netdev_err(vif->dev, "Too many frags\n");
+ netbk_fatal_tx_err(vif);
return -frags;
}
memcpy(txp, RING_GET_REQUEST(&vif->tx, cons + frags),
sizeof(*txp));
if (txp->size > first->size) {
- netdev_dbg(vif->dev, "Frags galore\n");
+ netdev_err(vif->dev, "Frag is bigger than frame.\n");
+ netbk_fatal_tx_err(vif);
return -frags;
}
@@ -921,8 +931,9 @@ static int netbk_count_requests(struct x
frags++;
if (unlikely((txp->offset + txp->size) > PAGE_SIZE)) {
- netdev_dbg(vif->dev, "txp->offset: %x, size: %u\n",
+ netdev_err(vif->dev, "txp->offset: %x, size: %u\n",
txp->offset, txp->size);
+ netbk_fatal_tx_err(vif);
return -frags;
}
} while ((txp++)->flags & XEN_NETTXF_more_data);
@@ -1095,7 +1106,8 @@ static int xen_netbk_get_extras(struct x
do {
if (unlikely(work_to_do-- <= 0)) {
- netdev_dbg(vif->dev, "Missing extra info\n");
+ netdev_err(vif->dev, "Missing extra info\n");
+ netbk_fatal_tx_err(vif);
return -EBADR;
}
@@ -1104,8 +1116,9 @@ static int xen_netbk_get_extras(struct x
if (unlikely(!extra.type ||
extra.type >= XEN_NETIF_EXTRA_TYPE_MAX)) {
vif->tx.req_cons = ++cons;
- netdev_dbg(vif->dev,
+ netdev_err(vif->dev,
"Invalid extra type: %d\n", extra.type);
+ netbk_fatal_tx_err(vif);
return -EINVAL;
}
@@ -1121,13 +1134,15 @@ static int netbk_set_skb_gso(struct xenv
struct xen_netif_extra_info *gso)
{
if (!gso->u.gso.size) {
- netdev_dbg(vif->dev, "GSO size must not be zero.\n");
+ netdev_err(vif->dev, "GSO size must not be zero.\n");
+ netbk_fatal_tx_err(vif);
return -EINVAL;
}
/* Currently only TCPv4 S.O. is supported. */
if (gso->u.gso.type != XEN_NETIF_GSO_TYPE_TCPV4) {
- netdev_dbg(vif->dev, "Bad GSO type %d.\n", gso->u.gso.type);
+ netdev_err(vif->dev, "Bad GSO type %d.\n", gso->u.gso.type);
+ netbk_fatal_tx_err(vif);
return -EINVAL;
}
@@ -1264,9 +1279,25 @@ static unsigned xen_netbk_tx_build_gops(
/* Get a netif from the list with work to do. */
vif = poll_net_schedule_list(netbk);
+ /* This can sometimes happen because the test of
+ * list_empty(net_schedule_list) at the top of the
+ * loop is unlocked. Just go back and have another
+ * look.
+ */
if (!vif)
continue;
+ if (vif->tx.sring->req_prod - vif->tx.req_cons >
+ XEN_NETIF_TX_RING_SIZE) {
+ netdev_err(vif->dev,
+ "Impossible number of requests. "
+ "req_prod %d, req_cons %d, size %ld\n",
+ vif->tx.sring->req_prod, vif->tx.req_cons,
+ XEN_NETIF_TX_RING_SIZE);
+ netbk_fatal_tx_err(vif);
+ continue;
+ }
+
RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, work_to_do);
if (!work_to_do) {
xenvif_put(vif);
@@ -1294,17 +1325,14 @@ static unsigned xen_netbk_tx_build_gops(
work_to_do = xen_netbk_get_extras(vif, extras,
work_to_do);
idx = vif->tx.req_cons;
- if (unlikely(work_to_do < 0)) {
- netbk_tx_err(vif, &txreq, idx);
+ if (unlikely(work_to_do < 0))
continue;
- }
}
ret = netbk_count_requests(vif, &txreq, txfrags, work_to_do);
- if (unlikely(ret < 0)) {
- netbk_tx_err(vif, &txreq, idx - ret);
+ if (unlikely(ret < 0))
continue;
- }
+
idx += ret;
if (unlikely(txreq.size < ETH_HLEN)) {
@@ -1316,11 +1344,11 @@ static unsigned xen_netbk_tx_build_gops(
/* No crossing a page as the payload mustn't fragment. */
if (unlikely((txreq.offset + txreq.size) > PAGE_SIZE)) {
- netdev_dbg(vif->dev,
+ netdev_err(vif->dev,
"txreq.offset: %x, size: %u, end: %lu\n",
txreq.offset, txreq.size,
(txreq.offset&~PAGE_MASK) + txreq.size);
- netbk_tx_err(vif, &txreq, idx);
+ netbk_fatal_tx_err(vif);
continue;
}
@@ -1348,8 +1376,8 @@ static unsigned xen_netbk_tx_build_gops(
gso = &extras[XEN_NETIF_EXTRA_TYPE_GSO - 1];
if (netbk_set_skb_gso(vif, skb, gso)) {
+ /* Failure in netbk_set_skb_gso is fatal. */
kfree_skb(skb);
- netbk_tx_err(vif, &txreq, idx);
continue;
}
}