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{
    "id": 808446,
    "url": "http://patchwork.ozlabs.org/api/patches/808446/?format=api",
    "web_url": "http://patchwork.ozlabs.org/project/netdev/patch/20170831222239.21509-3-tom@quantonium.net/",
    "project": {
        "id": 7,
        "url": "http://patchwork.ozlabs.org/api/projects/7/?format=api",
        "name": "Linux network development",
        "link_name": "netdev",
        "list_id": "netdev.vger.kernel.org",
        "list_email": "netdev@vger.kernel.org",
        "web_url": null,
        "scm_url": null,
        "webscm_url": null,
        "list_archive_url": "",
        "list_archive_url_format": "",
        "commit_url_format": ""
    },
    "msgid": "<20170831222239.21509-3-tom@quantonium.net>",
    "list_archive_url": null,
    "date": "2017-08-31T22:22:39",
    "name": "[net-next,2/2] flow_dissector: Add limits for encapsulation and EH",
    "commit_ref": null,
    "pull_url": null,
    "state": "superseded",
    "archived": true,
    "hash": "1940d62f0de68705df134b5f9ecb88eb3e9ffd20",
    "submitter": {
        "id": 72064,
        "url": "http://patchwork.ozlabs.org/api/people/72064/?format=api",
        "name": "Tom Herbert",
        "email": "tom@quantonium.net"
    },
    "delegate": {
        "id": 34,
        "url": "http://patchwork.ozlabs.org/api/users/34/?format=api",
        "username": "davem",
        "first_name": "David",
        "last_name": "Miller",
        "email": "davem@davemloft.net"
    },
    "mbox": "http://patchwork.ozlabs.org/project/netdev/patch/20170831222239.21509-3-tom@quantonium.net/mbox/",
    "series": [
        {
            "id": 914,
            "url": "http://patchwork.ozlabs.org/api/series/914/?format=api",
            "web_url": "http://patchwork.ozlabs.org/project/netdev/list/?series=914",
            "date": "2017-08-31T22:22:37",
            "name": "flow_dissector: Flow dissector fixes",
            "version": 1,
            "mbox": "http://patchwork.ozlabs.org/series/914/mbox/"
        }
    ],
    "comments": "http://patchwork.ozlabs.org/api/patches/808446/comments/",
    "check": "pending",
    "checks": "http://patchwork.ozlabs.org/api/patches/808446/checks/",
    "tags": {},
    "related": [],
    "headers": {
        "Return-Path": "<netdev-owner@vger.kernel.org>",
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        "X-Received": "by 10.84.130.39 with SMTP id 36mr4145116plc.143.1504218242778;\n\tThu, 31 Aug 2017 15:24:02 -0700 (PDT)",
        "From": "Tom Herbert <tom@quantonium.net>",
        "To": "davem@davemloft.net",
        "Cc": "netdev@vger.kernel.org, alex.popov@linux.com,\n\thannes@stressinduktion.org, Tom Herbert <tom@quantonium.net>",
        "Subject": "[PATCH net-next 2/2] flow_dissector: Add limits for encapsulation\n\tand EH",
        "Date": "Thu, 31 Aug 2017 15:22:39 -0700",
        "Message-Id": "<20170831222239.21509-3-tom@quantonium.net>",
        "X-Mailer": "git-send-email 2.11.0",
        "In-Reply-To": "<20170831222239.21509-1-tom@quantonium.net>",
        "References": "<20170831222239.21509-1-tom@quantonium.net>",
        "Sender": "netdev-owner@vger.kernel.org",
        "Precedence": "bulk",
        "List-ID": "<netdev.vger.kernel.org>",
        "X-Mailing-List": "netdev@vger.kernel.org"
    },
    "content": "In flow dissector there are no limits to the number of nested\nencapsulations that might be dissected which makes for a nice DOS\nattack. This patch limits for dissecting nested encapsulations\nas well as for dissecting over extension headers.\n\nReported-by: Hannes Frederic Sowa <hannes@stressinduktion.org>\nSigned-off-by: Tom Herbert <tom@quantonium.net>\n---\n net/core/flow_dissector.c | 48 ++++++++++++++++++++++++++++++++++++++++++++---\n 1 file changed, 45 insertions(+), 3 deletions(-)",
    "diff": "diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c\nindex 5110180a3e96..1bca748de27d 100644\n--- a/net/core/flow_dissector.c\n+++ b/net/core/flow_dissector.c\n@@ -396,6 +396,35 @@ __skb_flow_dissect_ipv6(const struct sk_buff *skb,\n \tkey_ip->ttl = iph->hop_limit;\n }\n \n+/* Maximum number of nested encapsulations that can be processed in\n+ * __skb_flow_dissect\n+ */\n+#define MAX_FLOW_DISSECT_ENCAPS\t5\n+\n+static bool skb_flow_dissect_encap_allowed(int *num_encaps, unsigned int *flags)\n+{\n+\t++*num_encaps;\n+\n+\tif (*num_encaps >= MAX_FLOW_DISSECT_ENCAPS) {\n+\t\tif (*num_encaps == MAX_FLOW_DISSECT_ENCAPS) {\n+\t\t\t/* Allow one more pass but ignore disregard\n+\t\t\t * further encapsulations\n+\t\t\t */\n+\t\t\t*flags |= FLOW_DISSECTOR_F_STOP_AT_ENCAP;\n+\t\t} else {\n+\t\t\t/* Max encaps reached */\n+\t\t\treturn  false;\n+\t\t}\n+\t}\n+\n+\treturn true;\n+}\n+\n+/* Maximum number of extension headers can be processed in __skb_flow_dissect\n+ * per IPv6 packet\n+ */\n+#define MAX_FLOW_DISSECT_EH\t5\n+\n /**\n  * __skb_flow_dissect - extract the flow_keys struct and return it\n  * @skb: sk_buff to extract the flow from, can be NULL if the rest are specified\n@@ -426,6 +455,7 @@ bool __skb_flow_dissect(const struct sk_buff *skb,\n \tstruct flow_dissector_key_tags *key_tags;\n \tstruct flow_dissector_key_vlan *key_vlan;\n \tenum flow_dissect_ret fdret;\n+\tint num_eh, num_encaps = 0;\n \tbool skip_vlan = false;\n \tu8 ip_proto = 0;\n \tbool ret;\n@@ -714,7 +744,9 @@ bool __skb_flow_dissect(const struct sk_buff *skb,\n \tcase FLOW_DISSECT_RET_OUT_GOOD:\n \t\tgoto out_good;\n \tcase FLOW_DISSECT_RET_PROTO_AGAIN:\n-\t\tgoto proto_again;\n+\t\tif (skb_flow_dissect_encap_allowed(&num_encaps, &flags))\n+\t\t\tgoto proto_again;\n+\t\tgoto out_good;\n \tcase FLOW_DISSECT_RET_CONTINUE:\n \tcase FLOW_DISSECT_RET_IPPROTO_AGAIN:\n \tcase FLOW_DISSECT_RET_IPPROTO_AGAIN_EH:\n@@ -724,6 +756,8 @@ bool __skb_flow_dissect(const struct sk_buff *skb,\n \t\tgoto out_bad;\n \t}\n \n+\tnum_eh = 0;\n+\n ip_proto_again:\n \tfdret = FLOW_DISSECT_RET_CONTINUE;\n \n@@ -844,10 +878,18 @@ bool __skb_flow_dissect(const struct sk_buff *skb,\n \t/* Process result of IP proto processing */\n \tswitch (fdret) {\n \tcase FLOW_DISSECT_RET_PROTO_AGAIN:\n-\t\tgoto proto_again;\n+\t\tif (skb_flow_dissect_encap_allowed(&num_encaps, &flags))\n+\t\t\tgoto proto_again;\n+\t\tbreak;\n \tcase FLOW_DISSECT_RET_IPPROTO_AGAIN:\n+\t\tif (skb_flow_dissect_encap_allowed(&num_encaps, &flags))\n+\t\t\tgoto ip_proto_again;\n+\t\tbreak;\n \tcase FLOW_DISSECT_RET_IPPROTO_AGAIN_EH:\n-\t\tgoto ip_proto_again;\n+\t\t++num_eh;\n+\t\tif (num_eh <= MAX_FLOW_DISSECT_EH)\n+\t\t\tgoto ip_proto_again;\n+\t\tbreak;\n \tcase FLOW_DISSECT_RET_OUT_GOOD:\n \tcase FLOW_DISSECT_RET_CONTINUE:\n \t\tbreak;\n",
    "prefixes": [
        "net-next",
        "2/2"
    ]
}