tipc: check minimum bearer MTU (CVE-2016-8632)
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Salvatore Bonaccorso
parent
59ebe22f2f
commit
27fc4207c6
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@ -43,6 +43,9 @@ linux (4.8.12-1) UNRELEASED; urgency=medium
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* [armel] dts: marvell: fix number of sata port for linkstation ls-gl
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(Closes: #845611)
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[ Salvatore Bonaccorso ]
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* tipc: check minimum bearer MTU (CVE-2016-8632)
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-- Uwe Kleine-König <ukleinek@debian.org> Sun, 04 Dec 2016 21:16:06 +0100
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linux (4.8.11-1) unstable; urgency=medium
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@ -0,0 +1,122 @@
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From: =?UTF-8?q?Michal=20Kube=C4=8Dek?= <mkubecek@suse.cz>
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Date: Fri, 2 Dec 2016 09:33:41 +0100
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Subject: tipc: check minimum bearer MTU
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Origin: https://git.kernel.org/linus/3de81b758853f0b29c61e246679d20b513c4cfec
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Qian Zhang (张谦) reported a potential socket buffer overflow in
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tipc_msg_build() which is also known as CVE-2016-8632: due to
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insufficient checks, a buffer overflow can occur if MTU is too short for
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even tipc headers. As anyone can set device MTU in a user/net namespace,
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this issue can be abused by a regular user.
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As agreed in the discussion on Ben Hutchings' original patch, we should
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check the MTU at the moment a bearer is attached rather than for each
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processed packet. We also need to repeat the check when bearer MTU is
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adjusted to new device MTU. UDP case also needs a check to avoid
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overflow when calculating bearer MTU.
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Fixes: b97bf3fd8f6a ("[TIPC] Initial merge")
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Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
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Reported-by: Qian Zhang (张谦) <zhangqian-c@360.cn>
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Acked-by: Ying Xue <ying.xue@windriver.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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net/tipc/bearer.c | 11 +++++++++--
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net/tipc/bearer.h | 13 +++++++++++++
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net/tipc/udp_media.c | 5 +++++
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3 files changed, 27 insertions(+), 2 deletions(-)
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diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
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index 975dbeb..52d7476 100644
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--- a/net/tipc/bearer.c
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+++ b/net/tipc/bearer.c
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@@ -421,6 +421,10 @@ int tipc_enable_l2_media(struct net *net, struct tipc_bearer *b,
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dev = dev_get_by_name(net, driver_name);
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if (!dev)
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return -ENODEV;
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+ if (tipc_mtu_bad(dev, 0)) {
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+ dev_put(dev);
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+ return -EINVAL;
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+ }
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/* Associate TIPC bearer with L2 bearer */
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rcu_assign_pointer(b->media_ptr, dev);
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@@ -610,8 +614,6 @@ static int tipc_l2_device_event(struct notifier_block *nb, unsigned long evt,
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if (!b)
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return NOTIFY_DONE;
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- b->mtu = dev->mtu;
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-
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switch (evt) {
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case NETDEV_CHANGE:
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if (netif_carrier_ok(dev))
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@@ -624,6 +626,11 @@ static int tipc_l2_device_event(struct notifier_block *nb, unsigned long evt,
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tipc_reset_bearer(net, b);
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break;
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case NETDEV_CHANGEMTU:
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+ if (tipc_mtu_bad(dev, 0)) {
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+ bearer_disable(net, b);
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+ break;
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+ }
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+ b->mtu = dev->mtu;
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tipc_reset_bearer(net, b);
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break;
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case NETDEV_CHANGEADDR:
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diff --git a/net/tipc/bearer.h b/net/tipc/bearer.h
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index 78892e2f..278ff7f 100644
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--- a/net/tipc/bearer.h
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+++ b/net/tipc/bearer.h
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@@ -39,6 +39,7 @@
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#include "netlink.h"
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#include "core.h"
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+#include "msg.h"
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#include <net/genetlink.h>
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#define MAX_MEDIA 3
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@@ -59,6 +60,9 @@
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#define TIPC_MEDIA_TYPE_IB 2
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#define TIPC_MEDIA_TYPE_UDP 3
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+/* minimum bearer MTU */
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+#define TIPC_MIN_BEARER_MTU (MAX_H_SIZE + INT_H_SIZE)
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+
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/**
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* struct tipc_media_addr - destination address used by TIPC bearers
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* @value: address info (format defined by media)
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@@ -215,4 +219,13 @@ void tipc_bearer_xmit(struct net *net, u32 bearer_id,
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void tipc_bearer_bc_xmit(struct net *net, u32 bearer_id,
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struct sk_buff_head *xmitq);
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+/* check if device MTU is too low for tipc headers */
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+static inline bool tipc_mtu_bad(struct net_device *dev, unsigned int reserve)
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+{
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+ if (dev->mtu >= TIPC_MIN_BEARER_MTU + reserve)
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+ return false;
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+ netdev_warn(dev, "MTU too low for tipc bearer\n");
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+ return true;
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+}
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+
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#endif /* _TIPC_BEARER_H */
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diff --git a/net/tipc/udp_media.c b/net/tipc/udp_media.c
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index 78cab9c..b58dc95 100644
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--- a/net/tipc/udp_media.c
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+++ b/net/tipc/udp_media.c
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@@ -697,6 +697,11 @@ static int tipc_udp_enable(struct net *net, struct tipc_bearer *b,
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udp_conf.local_ip.s_addr = htonl(INADDR_ANY);
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udp_conf.use_udp_checksums = false;
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ub->ifindex = dev->ifindex;
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+ if (tipc_mtu_bad(dev, sizeof(struct iphdr) +
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+ sizeof(struct udphdr))) {
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+ err = -EINVAL;
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+ goto err;
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+ }
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b->mtu = dev->mtu - sizeof(struct iphdr)
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- sizeof(struct udphdr);
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#if IS_ENABLED(CONFIG_IPV6)
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--
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2.1.4
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@ -102,6 +102,7 @@ bugfix/all/fs-Give-dentry-to-inode_change_ok-instead-of-inode.patch
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bugfix/all/fs-Avoid-premature-clearing-of-capabilities.patch
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bugfix/all/vfio-pci-Fix-integer-overflows-bitmask-check.patch
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bugfix/all/mnt-Add-a-per-mount-namespace-limit-on-the-number-of.patch
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bugfix/all/tipc-check-minimum-bearer-MTU.patch
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# ABI maintenance
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