From: Greg Kroah-Hartman <gregkh@linuxfoundation•org>
To: linux-kernel@vger•kernel.org, netdev@vger•kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation•org>,
stable@vger•kernel.org, "David S. Miller" <davem@davemloft•net>,
Peter Oskolkov <posk@google•com>,
Eric Dumazet <edumazet@google•com>,
Florian Westphal <fw@strlen•de>,
Stephen Hemminger <stephen@networkplumber•org>
Subject: [PATCH 4.9 61/71] ip: discard IPv4 datagrams with overlapping segments.
Date: Tue, 16 Oct 2018 19:09:58 +0200 [thread overview]
Message-ID: <20181016170542.451084535@linuxfoundation.org> (raw)
In-Reply-To: <20181016170539.315587743@linuxfoundation.org>
4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Peter Oskolkov <posk@google•com>
This behavior is required in IPv6, and there is little need
to tolerate overlapping fragments in IPv4. This change
simplifies the code and eliminates potential DDoS attack vectors.
Tested: ran ip_defrag selftest (not yet available uptream).
Suggested-by: David S. Miller <davem@davemloft•net>
Signed-off-by: Peter Oskolkov <posk@google•com>
Signed-off-by: Eric Dumazet <edumazet@google•com>
Cc: Florian Westphal <fw@strlen•de>
Acked-by: Stephen Hemminger <stephen@networkplumber•org>
Signed-off-by: David S. Miller <davem@davemloft•net>
(cherry picked from commit 7969e5c40dfd04799d4341f1b7cd266b6e47f227)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation•org>
---
include/uapi/linux/snmp.h | 1
net/ipv4/ip_fragment.c | 77 +++++++++++-----------------------------------
net/ipv4/proc.c | 1
3 files changed, 22 insertions(+), 57 deletions(-)
--- a/include/uapi/linux/snmp.h
+++ b/include/uapi/linux/snmp.h
@@ -55,6 +55,7 @@ enum
IPSTATS_MIB_ECT1PKTS, /* InECT1Pkts */
IPSTATS_MIB_ECT0PKTS, /* InECT0Pkts */
IPSTATS_MIB_CEPKTS, /* InCEPkts */
+ IPSTATS_MIB_REASM_OVERLAPS, /* ReasmOverlaps */
__IPSTATS_MIB_MAX
};
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -275,6 +275,7 @@ static int ip_frag_reinit(struct ipq *qp
/* Add new segment to existing queue. */
static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
{
+ struct net *net = container_of(qp->q.net, struct net, ipv4.frags);
struct sk_buff *prev, *next;
struct net_device *dev;
unsigned int fragsize;
@@ -355,65 +356,23 @@ static int ip_frag_queue(struct ipq *qp,
}
found:
- /* We found where to put this one. Check for overlap with
- * preceding fragment, and, if needed, align things so that
- * any overlaps are eliminated.
+ /* RFC5722, Section 4, amended by Errata ID : 3089
+ * When reassembling an IPv6 datagram, if
+ * one or more its constituent fragments is determined to be an
+ * overlapping fragment, the entire datagram (and any constituent
+ * fragments) MUST be silently discarded.
+ *
+ * We do the same here for IPv4.
*/
- if (prev) {
- int i = (prev->ip_defrag_offset + prev->len) - offset;
- if (i > 0) {
- offset += i;
- err = -EINVAL;
- if (end <= offset)
- goto err;
- err = -ENOMEM;
- if (!pskb_pull(skb, i))
- goto err;
- if (skb->ip_summed != CHECKSUM_UNNECESSARY)
- skb->ip_summed = CHECKSUM_NONE;
- }
- }
-
- err = -ENOMEM;
-
- while (next && next->ip_defrag_offset < end) {
- int i = end - next->ip_defrag_offset; /* overlap is 'i' bytes */
-
- if (i < next->len) {
- int delta = -next->truesize;
-
- /* Eat head of the next overlapped fragment
- * and leave the loop. The next ones cannot overlap.
- */
- if (!pskb_pull(next, i))
- goto err;
- delta += next->truesize;
- if (delta)
- add_frag_mem_limit(qp->q.net, delta);
- next->ip_defrag_offset += i;
- qp->q.meat -= i;
- if (next->ip_summed != CHECKSUM_UNNECESSARY)
- next->ip_summed = CHECKSUM_NONE;
- break;
- } else {
- struct sk_buff *free_it = next;
-
- /* Old fragment is completely overridden with
- * new one drop it.
- */
- next = next->next;
-
- if (prev)
- prev->next = next;
- else
- qp->q.fragments = next;
-
- qp->q.meat -= free_it->len;
- sub_frag_mem_limit(qp->q.net, free_it->truesize);
- kfree_skb(free_it);
- }
- }
+ /* Is there an overlap with the previous fragment? */
+ if (prev &&
+ (prev->ip_defrag_offset + prev->len) > offset)
+ goto discard_qp;
+
+ /* Is there an overlap with the next fragment? */
+ if (next && next->ip_defrag_offset < end)
+ goto discard_qp;
/* Note : skb->ip_defrag_offset and skb->dev share the same location */
dev = skb->dev;
@@ -461,6 +420,10 @@ found:
skb_dst_drop(skb);
return -EINPROGRESS;
+discard_qp:
+ inet_frag_kill(&qp->q);
+ err = -EINVAL;
+ __IP_INC_STATS(net, IPSTATS_MIB_REASM_OVERLAPS);
err:
kfree_skb(skb);
return err;
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -134,6 +134,7 @@ static const struct snmp_mib snmp4_ipext
SNMP_MIB_ITEM("InECT1Pkts", IPSTATS_MIB_ECT1PKTS),
SNMP_MIB_ITEM("InECT0Pkts", IPSTATS_MIB_ECT0PKTS),
SNMP_MIB_ITEM("InCEPkts", IPSTATS_MIB_CEPKTS),
+ SNMP_MIB_ITEM("ReasmOverlaps", IPSTATS_MIB_REASM_OVERLAPS),
SNMP_MIB_SENTINEL
};
next prev parent reply other threads:[~2018-10-16 17:09 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20181016170539.315587743@linuxfoundation.org>
2018-10-16 17:09 ` [PATCH 4.9 43/71] inet: frags: change inet_frags_init_net() return value Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 44/71] inet: frags: add a pointer to struct netns_frags Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 45/71] inet: frags: refactor ipfrag_init() Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 46/71] inet: frags: refactor ipv6_frag_init() Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 47/71] inet: frags: refactor lowpan_net_frag_init() Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 48/71] ipv6: export ip6 fragments sysctl to unprivileged users Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 49/71] rhashtable: add schedule points Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 50/71] inet: frags: use rhashtables for reassembly units Greg Kroah-Hartman
2018-10-26 13:39 ` Stefan Schmidt
2018-11-29 12:54 ` Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 51/71] inet: frags: remove some helpers Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 52/71] inet: frags: get rif of inet_frag_evicting() Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 53/71] inet: frags: remove inet_frag_maybe_warn_overflow() Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 54/71] inet: frags: break the 2GB limit for frags storage Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 55/71] inet: frags: do not clone skb in ip_expire() Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 56/71] ipv6: frags: rewrite ip6_expire_frag_queue() Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 57/71] rhashtable: reorganize struct rhashtable layout Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 58/71] inet: frags: reorganize struct netns_frags Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 59/71] inet: frags: get rid of ipfrag_skb_cb/FRAG_CB Greg Kroah-Hartman
2018-10-16 17:09 ` [PATCH 4.9 60/71] inet: frags: fix ip6frag_low_thresh boundary Greg Kroah-Hartman
2018-10-16 17:09 ` Greg Kroah-Hartman [this message]
2018-10-16 17:09 ` [PATCH 4.9 62/71] net: speed up skb_rbtree_purge() Greg Kroah-Hartman
2018-10-16 17:10 ` [PATCH 4.9 63/71] net: modify skb_rbtree_purge to return the truesize of all purged skbs Greg Kroah-Hartman
2018-10-16 17:10 ` [PATCH 4.9 64/71] ipv6: defrag: drop non-last frags smaller than min mtu Greg Kroah-Hartman
2018-10-16 17:10 ` [PATCH 4.9 65/71] net: pskb_trim_rcsum() and CHECKSUM_COMPLETE are friends Greg Kroah-Hartman
2018-10-16 17:10 ` [PATCH 4.9 66/71] net: add rb_to_skb() and other rb tree helpers Greg Kroah-Hartman
2018-10-16 17:10 ` [PATCH 4.9 67/71] ip: use rb trees for IP frag queue Greg Kroah-Hartman
2018-10-16 17:10 ` [PATCH 4.9 68/71] ip: add helpers to process in-order fragments faster Greg Kroah-Hartman
2018-10-16 17:10 ` [PATCH 4.9 69/71] ip: process in-order fragments efficiently Greg Kroah-Hartman
2018-10-16 17:10 ` [PATCH 4.9 70/71] ip: frags: fix crash in ip_do_fragment() Greg Kroah-Hartman
2018-10-16 17:10 ` [PATCH 4.9 71/71] ipv4: frags: precedence bug in ip_expire() Greg Kroah-Hartman
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