[dpdk-stable] patch 'ip_frag: remove padding length of fragment' has been queued to stable release 19.11.7

[Christian Ehrhardt]

Hi,

FYI, your patch has been queued to stable release 19.11.7

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 02/06/21. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Queued patches are on a temporary branch at:
https://github.com/cpaelzer/dpdk-stable-queue

This queued commit can be viewed at:
https://github.com/cpaelzer/dpdk-stable-queue/commit/b29a3aaae73d8817ed2d3fe369b4d366b704b156

Thanks.

Christian Ehrhardt <christian.ehrhardt at canonical.com>

---
>From b29a3aaae73d8817ed2d3fe369b4d366b704b156 Mon Sep 17 00:00:00 2001
From: Yicai Lu <luyicai at huawei.com>
Date: Wed, 16 Dec 2020 21:36:30 +0800
Subject: [PATCH] ip_frag: remove padding length of fragment

[ upstream commit 324242fb510b65644f025a996404abcd0b8199a6 ]

In some situations, we would get several ip fragments, which total
data length is less than min_ip_len(64) and padding with zeros.
We simulated intermediate fragments by modifying the MTU.
To illustrate the problem, we simplify the packet format and
ignore the impact of the packet header.In namespace2,
a packet whose data length is 1520 is sent.
When the packet passes tap2, the packet is divided into two
fragments: fragment A and B, similar to (1520 = 1510 + 10).
When the packet passes tap3, the larger fragment packet A is
divided into two fragments A1 and A2, similar to (1510 = 1500 + 10).
Finally, the bond interface receives three fragments:
A1, A2, and B (1520 = 1500 + 10 + 10).
One fragmented packet A2 is smaller than the minimum Ethernet
frame length, so it needs to be padded.

|---------------------------------------------------|
|                      HOST                         |
| |--------------|   |----------------------------| |
| |      ns2     |   |      |--------------|      | |
| |  |--------|  |   |  |--------|    |--------|  | |
| |  |  tap1  |  |   |  |  tap2  | ns1|  tap3  |  | |
| |  |mtu=1510|  |   |  |mtu=1510|    |mtu=1500|  | |
| |--|1.1.1.1 |--|   |--|1.1.1.2 |----|2.1.1.1 |--| |
|    |--------|         |--------|    |--------|    |
|         |                 |              |        |
|         |-----------------|              |        |
|                                          |        |
|                                      |--------|   |
|                                      |  bond  |   |
|--------------------------------------|mtu=1500|---|
                                       |--------|

When processing the preceding packets above,
DPDK would aggregate fragmented packets A2 and B.
And error packets are generated, which padding(zero)
is displayed in the middle of the packet.

A2 + B:
0000   fa 16 3e 9f fb 82 fa 47 b2 57 dc 20 08 00 45 00
0010   00 33 b4 66 00 ba 3f 01 c1 a5 01 01 01 01 02 01
0020   01 02 c0 c1 c2 c3 c4 c5 c6 c7 00 00 00 00 00 00
0030   00 00 00 00 00 00 00 00 00 00 00 00 c8 c9 ca cb
0040   cc cd ce cf d0 d1 d2 d3 d4 d5 d6 d7 d8 d9 da db
0050   dc dd de df e0 e1 e2 e3 e4 e5 e6

So, we would calculate the length of padding, and remove
the padding in pkt_len and data_len before aggregation.
And also we have the fix for both ipv4 and ipv6.

Fixes: 7f0983ee331c ("ip_frag: check fragment length of incoming packet")

Signed-off-by: Yicai Lu <luyicai at huawei.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev at intel.com>
---
 lib/librte_ip_frag/rte_ipv4_reassembly.c | 11 ++++++++---
 lib/librte_ip_frag/rte_ipv6_reassembly.c |  9 +++++++--
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/lib/librte_ip_frag/rte_ipv4_reassembly.c b/lib/librte_ip_frag/rte_ipv4_reassembly.c
index 1dda8aca02..69666c8b82 100644
--- a/lib/librte_ip_frag/rte_ipv4_reassembly.c
+++ b/lib/librte_ip_frag/rte_ipv4_reassembly.c
@@ -104,6 +104,7 @@ rte_ipv4_frag_reassemble_packet(struct rte_ip_frag_tbl *tbl,
 	const unaligned_uint64_t *psd;
 	uint16_t flag_offset, ip_ofs, ip_flag;
 	int32_t ip_len;
+	int32_t trim;
 
 	flag_offset = rte_be_to_cpu_16(ip_hdr->fragment_offset);
 	ip_ofs = (uint16_t)(flag_offset & RTE_IPV4_HDR_OFFSET_MASK);
@@ -117,14 +118,15 @@ rte_ipv4_frag_reassemble_packet(struct rte_ip_frag_tbl *tbl,
 
 	ip_ofs *= RTE_IPV4_HDR_OFFSET_UNITS;
 	ip_len = rte_be_to_cpu_16(ip_hdr->total_length) - mb->l3_len;
+	trim = mb->pkt_len - (ip_len + mb->l3_len + mb->l2_len);
 
 	IP_FRAG_LOG(DEBUG, "%s:%d:\n"
-		"mbuf: %p, tms: %" PRIu64
-		", key: <%" PRIx64 ", %#x>, ofs: %u, len: %d, flags: %#x\n"
+		"mbuf: %p, tms: %" PRIu64 ", key: <%" PRIx64 ", %#x>"
+		"ofs: %u, len: %d, padding: %d, flags: %#x\n"
 		"tbl: %p, max_cycles: %" PRIu64 ", entry_mask: %#x, "
 		"max_entries: %u, use_entries: %u\n\n",
 		__func__, __LINE__,
-		mb, tms, key.src_dst[0], key.id, ip_ofs, ip_len, ip_flag,
+		mb, tms, key.src_dst[0], key.id, ip_ofs, ip_len, trim, ip_flag,
 		tbl, tbl->max_cycles, tbl->entry_mask, tbl->max_entries,
 		tbl->use_entries);
 
@@ -134,6 +136,9 @@ rte_ipv4_frag_reassemble_packet(struct rte_ip_frag_tbl *tbl,
 		return NULL;
 	}
 
+	if (unlikely(trim > 0))
+		rte_pktmbuf_trim(mb, trim);
+
 	/* try to find/add entry into the fragment's table. */
 	if ((fp = ip_frag_find(tbl, dr, &key, tms)) == NULL) {
 		IP_FRAG_MBUF2DR(dr, mb);
diff --git a/lib/librte_ip_frag/rte_ipv6_reassembly.c b/lib/librte_ip_frag/rte_ipv6_reassembly.c
index ad01055184..6bc0bf792a 100644
--- a/lib/librte_ip_frag/rte_ipv6_reassembly.c
+++ b/lib/librte_ip_frag/rte_ipv6_reassembly.c
@@ -142,6 +142,7 @@ rte_ipv6_frag_reassemble_packet(struct rte_ip_frag_tbl *tbl,
 	struct ip_frag_key key;
 	uint16_t ip_ofs;
 	int32_t ip_len;
+	int32_t trim;
 
 	rte_memcpy(&key.src_dst[0], ip_hdr->src_addr, 16);
 	rte_memcpy(&key.src_dst[2], ip_hdr->dst_addr, 16);
@@ -158,16 +159,17 @@ rte_ipv6_frag_reassemble_packet(struct rte_ip_frag_tbl *tbl,
 	 * this is what we remove from the payload len.
 	 */
 	ip_len = rte_be_to_cpu_16(ip_hdr->payload_len) - sizeof(*frag_hdr);
+	trim = mb->pkt_len - (ip_len + mb->l3_len + mb->l2_len);
 
 	IP_FRAG_LOG(DEBUG, "%s:%d:\n"
 		"mbuf: %p, tms: %" PRIu64
 		", key: <" IPv6_KEY_BYTES_FMT ", %#x>, "
-		"ofs: %u, len: %d, flags: %#x\n"
+		"ofs: %u, len: %d, padding: %d, flags: %#x\n"
 		"tbl: %p, max_cycles: %" PRIu64 ", entry_mask: %#x, "
 		"max_entries: %u, use_entries: %u\n\n",
 		__func__, __LINE__,
 		mb, tms, IPv6_KEY_BYTES(key.src_dst), key.id, ip_ofs, ip_len,
-		RTE_IPV6_GET_MF(frag_hdr->frag_data),
+		trim, RTE_IPV6_GET_MF(frag_hdr->frag_data),
 		tbl, tbl->max_cycles, tbl->entry_mask, tbl->max_entries,
 		tbl->use_entries);
 
@@ -177,6 +179,9 @@ rte_ipv6_frag_reassemble_packet(struct rte_ip_frag_tbl *tbl,
 		return NULL;
 	}
 
+	if (unlikely(trim > 0))
+		rte_pktmbuf_trim(mb, trim);
+
 	/* try to find/add entry into the fragment's table. */
 	fp = ip_frag_find(tbl, dr, &key, tms);
 	if (fp == NULL) {
-- 
2.30.0

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2021-02-04 12:04:29.982596555 +0100
+++ 0045-ip_frag-remove-padding-length-of-fragment.patch	2021-02-04 12:04:27.958789659 +0100
@@ -1 +1 @@
-From 324242fb510b65644f025a996404abcd0b8199a6 Mon Sep 17 00:00:00 2001
+From b29a3aaae73d8817ed2d3fe369b4d366b704b156 Mon Sep 17 00:00:00 2001
@@ -5,0 +6,2 @@
+[ upstream commit 324242fb510b65644f025a996404abcd0b8199a6 ]
+
@@ -56 +57,0 @@
-Cc: stable at dpdk.org