[PATCH 3.13.y-ckt 03/57] ipv6: addrconf: validate new MTU before applying it

From	Kamal Mostafa <kamal@canonical.com>
Newsgroups	linux.kernel
Subject	[PATCH 3.13.y-ckt 03/57] ipv6: addrconf: validate new MTU before applying it
Date	2015-09-22 21:20 +0200
Message-ID	<qbBgE-665-43@gated-at.bofh.it> (permalink)
References	<qbzRv-3UF-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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3.13.11-ckt27 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Marcelo Leitner <mleitner@redhat.com>

commit 77751427a1ff25b27d47a4c36b12c3c8667855ac upstream.

Currently we don't check if the new MTU is valid or not and this allows
one to configure a smaller than minimum allowed by RFCs or even bigger
than interface own MTU, which is a problem as it may lead to packet
drops.

If you have a daemon like NetworkManager running, this may be exploited
by remote attackers by forging RA packets with an invalid MTU, possibly
leading to a DoS. (NetworkManager currently only validates for values
too small, but not for too big ones.)

The fix is just to make sure the new value is valid. That is, between
IPV6_MIN_MTU and interface's MTU.

Note that similar check is already performed at
ndisc_router_discovery(), for when kernel itself parses the RA.

Signed-off-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 net/ipv6/addrconf.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 0e8ae69..2be400d 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -4614,6 +4614,21 @@ int addrconf_sysctl_forward(struct ctl_table *ctl, int write,
 	return ret;
 }
 
+static
+int addrconf_sysctl_mtu(struct ctl_table *ctl, int write,
+			void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	struct inet6_dev *idev = ctl->extra1;
+	int min_mtu = IPV6_MIN_MTU;
+	struct ctl_table lctl;
+
+	lctl = *ctl;
+	lctl.extra1 = &min_mtu;
+	lctl.extra2 = idev ? &idev->dev->mtu : NULL;
+
+	return proc_dointvec_minmax(&lctl, write, buffer, lenp, ppos);
+}
+
 static void dev_disable_change(struct inet6_dev *idev)
 {
 	struct netdev_notifier_info info;
@@ -4725,7 +4740,7 @@ static struct addrconf_sysctl_table
 			.data		= &ipv6_devconf.mtu6,
 			.maxlen		= sizeof(int),
 			.mode		= 0644,
-			.proc_handler	= proc_dointvec,
+			.proc_handler	= addrconf_sysctl_mtu,
 		},
 		{
 			.procname	= "accept_ra",
-- 
1.9.1

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Thread

[3.13.y-ckt stable] Linux 3.13.11-ckt27 stable review Kamal Mostafa <kamal@canonical.com> - 2015-09-22 19:50 +0200
  [PATCH 3.13.y-ckt 15/57] target/iscsi: Fix double free of a TUR followed by a solicited NOPOUT Kamal Mostafa <kamal@canonical.com> - 2015-09-22 19:50 +0200
  [PATCH 3.13.y-ckt 12/57] xen-blkback: replace work_pending with work_busy in purge_persistent_gnt() Kamal Mostafa <kamal@canonical.com> - 2015-09-22 19:50 +0200
  [PATCH 3.13.y-ckt 16/57] rbd: fix copyup completion race Kamal Mostafa <kamal@canonical.com> - 2015-09-22 19:50 +0200
  [PATCH 3.13.y-ckt 57/57] net: gso: use feature flag argument in all protocol gso handlers Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 50/57] ipv6: lock socket in ip6_datagram_connect() Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 47/57] rds: fix an integer overflow test in rds_info_getsockopt() Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 53/57] net: pktgen: fix race between pktgen_thread_worker() and kthread_stop() Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 54/57] net: call rcu_read_lock early in process_backlog Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 52/57] net/tipc: initialize security state for new connection socket Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 40/57] ipc/sem.c: update/correct memory barriers Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 21/57] perf: Fix fasync handling on inherited events Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 51/57] rtnetlink: verify IFLA_VF_INFO attributes before passing them to driver Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 56/57] netlink: don't hold mutex in rcu callback when releasing mmapd ring Kamal Mostafa <kamal@canonical.com> - 2015-09-22 20:00 +0200
  [PATCH 3.13.y-ckt 48/57] udp: fix dst races with multicast early demux Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:00 +0200
  [PATCH 3.13.y-ckt 49/57] sparc64: Fix userspace FPU register corruptions. Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:00 +0200
  [PATCH 3.13.y-ckt 44/57] ip6_gre: release cached dst on tunnel removal Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:00 +0200
  [PATCH 3.13.y-ckt 46/57] net: Fix skb_set_peeked use-after-free bug Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:00 +0200
  [PATCH 3.13.y-ckt 39/57] ipc/sem.c: change memory barrier in sem_lock() to smp_rmb() Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 43/57] batman-adv: protect tt_local_entry from concurrent delete events Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 36/57] crypto: caam - fix memory corruption in ahash_final_ctx Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 32/57] libiscsi: Fix host busy blocking during connection teardown Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 24/57] ipc: modify message queue accounting to not take kernel data structures into account Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 42/57] arm64: KVM: Fix host crash when injecting a fault into a 32bit guest Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 35/57] EDAC, ppc4xx: Access mci->csrows array elements properly Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 33/57] libfc: Fix fc_exch_recv_req() error path Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 38/57] ipc,sem: fix use after free on IPC_RMID after a task using same semaphore set exits Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 37/57] mm/hwpoison: fix page refcount of unknown non LRU page Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 25/57] ocfs2: fix BUG in ocfs2_downconvert_thread_do_work() Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 17/57] md/raid1: extend spinlock to protect raid1_end_read_request against inconsistencies Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 45/57] net: Fix RCU splat in af_key Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 34/57] libfc: Fix fc_fcp_cleanup_each_cmd() Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 41/57] Add factory recertified Crucial M500s to blacklist Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:10 +0200
  [PATCH 3.13.y-ckt 04/57] virtio-net: drop NETIF_F_FRAGLIST Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 14/57] regmap: regcache-rbtree: Clean new present bits on present bitmap resize Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 27/57] KVM: x86: Use adjustment in guest cycles when handling MSR_IA32_TSC_ADJUST Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 05/57] RDS: verify the underlying transport exists before creating a connection Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 07/57] xen/gntdevt: Fix race condition in gntdev_release() Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 13/57] USB: sierra: add 1199:68AB device ID Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 31/57] drm/radeon: add new OLAND pci id Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 10/57] crypto: ixp4xx - Remove bogus BUG_ON on scattered dst buffer Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 29/57] dm thin metadata: delete btrees when releasing metadata snapshot Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 20/57] xhci: fix off by one error in TRB DMA address boundary check Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 30/57] dm btree: add ref counting ops for the leaves of top level btrees Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 18/57] target: REPORT LUNS should return LUN 0 even for dynamic ACLs Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 02/57] md: flush ->event_work before stopping array. Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 03/57] ipv6: addrconf: validate new MTU before applying it Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 22/57] mm, vmscan: Do not wait for page writeback for GFP_NOFS allocations Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 19/57] MIPS: Fix sched_getaffinity with MT FPAFF enabled Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 28/57] localmodconfig: Use Kbuild files too Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 09/57] nfsd: Drop BUG_ON and ignore SECLABEL on absent filesystem Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 11/57] xen-blkfront: don't add indirect pages to list when !feature_persistent Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 08/57] PCI: Restore PCI_MSIX_FLAGS_BIRMASK definition Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 23/57] MIPS: Make set_pte() SMP safe. Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200
  [PATCH 3.13.y-ckt 26/57] fsnotify: fix oops in fsnotify_clear_marks_by_group_flags() Kamal Mostafa <kamal@canonical.com> - 2015-09-22 21:20 +0200

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