[LTP] [PATCH v2 1/2] lib/tst_checksum: add crc32c checksum

[LTP] [PATCH v2 1/2] lib/tst_checksum: add crc32c checksum

[Alexey Kodanev]

It will be used to make a SCTP packet in the test.

Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
---
v2: As suggested by Cyril:
    * updated the docs, added section 2.2.25
    * added 'tst_' prefix
    * changed type 'int' to 'size_t' for the buffer length

 doc/test-writing-guidelines.txt |    6 +++
 include/tst_checksum.h          |   29 ++++++++++++
 lib/tst_checksum.c              |   95 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 130 insertions(+), 0 deletions(-)
 create mode 100644 include/tst_checksum.h
 create mode 100644 lib/tst_checksum.c

diff --git a/doc/test-writing-guidelines.txt b/doc/test-writing-guidelines.txt
index cbbfe6c..8e405a0 100644
--- a/doc/test-writing-guidelines.txt
+++ b/doc/test-writing-guidelines.txt
@@ -1366,6 +1366,12 @@ For reference to tainted kernels, see kernel documentation:
 Documentation/admin-guide/tainted-kernels.rst or
 https://www.kernel.org/doc/html/latest/admin-guide/tainted-kernels.html
 
+2.2.25 Checksums
+^^^^^^^^^^^^^^^^
+
+CRC32c checksum generation is supported by LTP. In order to use it, the
+test should include "tst_checksum.h" header, then can call tst_crc32c().
+
 2.3 Writing a testcase in shell
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/include/tst_checksum.h b/include/tst_checksum.h
new file mode 100644
index 0000000..02257dd
--- /dev/null
+++ b/include/tst_checksum.h
@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2018 Oracle and/or its affiliates. All Rights Reserved.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef TST_CHECKSUM_H__
+#define TST_CHECKSUM_H__
+
+#include <stdint.h>
+#include <stddef.h>
+
+/*
+ * Generates CRC32c checksum.
+ */
+uint32_t tst_crc32c(uint8_t *buf, size_t buf_len);
+
+#endif
diff --git a/lib/tst_checksum.c b/lib/tst_checksum.c
new file mode 100644
index 0000000..6932c24
--- /dev/null
+++ b/lib/tst_checksum.c
@@ -0,0 +1,95 @@
+/*
+ * Copyright (c) 2018 Oracle and/or its affiliates. All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "tst_checksum.h"
+
+static const uint32_t crc32c_table[] = {
+	0x00000000, 0xf26b8303, 0xe13b70f7, 0x1350f3f4,
+	0xc79a971f, 0x35f1141c, 0x26a1e7e8, 0xd4ca64eb,
+	0x8ad958cf, 0x78b2dbcc, 0x6be22838, 0x9989ab3b,
+	0x4d43cfd0, 0xbf284cd3, 0xac78bf27, 0x5e133c24,
+	0x105ec76f, 0xe235446c, 0xf165b798, 0x030e349b,
+	0xd7c45070, 0x25afd373, 0x36ff2087, 0xc494a384,
+	0x9a879fa0, 0x68ec1ca3, 0x7bbcef57, 0x89d76c54,
+	0x5d1d08bf, 0xaf768bbc, 0xbc267848, 0x4e4dfb4b,
+	0x20bd8ede, 0xd2d60ddd, 0xc186fe29, 0x33ed7d2a,
+	0xe72719c1, 0x154c9ac2, 0x061c6936, 0xf477ea35,
+	0xaa64d611, 0x580f5512, 0x4b5fa6e6, 0xb93425e5,
+	0x6dfe410e, 0x9f95c20d, 0x8cc531f9, 0x7eaeb2fa,
+	0x30e349b1, 0xc288cab2, 0xd1d83946, 0x23b3ba45,
+	0xf779deae, 0x05125dad, 0x1642ae59, 0xe4292d5a,
+	0xba3a117e, 0x4851927d, 0x5b016189, 0xa96ae28a,
+	0x7da08661, 0x8fcb0562, 0x9c9bf696, 0x6ef07595,
+	0x417b1dbc, 0xb3109ebf, 0xa0406d4b, 0x522bee48,
+	0x86e18aa3, 0x748a09a0, 0x67dafa54, 0x95b17957,
+	0xcba24573, 0x39c9c670, 0x2a993584, 0xd8f2b687,
+	0x0c38d26c, 0xfe53516f, 0xed03a29b, 0x1f682198,
+	0x5125dad3, 0xa34e59d0, 0xb01eaa24, 0x42752927,
+	0x96bf4dcc, 0x64d4cecf, 0x77843d3b, 0x85efbe38,
+	0xdbfc821c, 0x2997011f, 0x3ac7f2eb, 0xc8ac71e8,
+	0x1c661503, 0xee0d9600, 0xfd5d65f4, 0x0f36e6f7,
+	0x61c69362, 0x93ad1061, 0x80fde395, 0x72966096,
+	0xa65c047d, 0x5437877e, 0x4767748a, 0xb50cf789,
+	0xeb1fcbad, 0x197448ae, 0x0a24bb5a, 0xf84f3859,
+	0x2c855cb2, 0xdeeedfb1, 0xcdbe2c45, 0x3fd5af46,
+	0x7198540d, 0x83f3d70e, 0x90a324fa, 0x62c8a7f9,
+	0xb602c312, 0x44694011, 0x5739b3e5, 0xa55230e6,
+	0xfb410cc2, 0x092a8fc1, 0x1a7a7c35, 0xe811ff36,
+	0x3cdb9bdd, 0xceb018de, 0xdde0eb2a, 0x2f8b6829,
+	0x82f63b78, 0x709db87b, 0x63cd4b8f, 0x91a6c88c,
+	0x456cac67, 0xb7072f64, 0xa457dc90, 0x563c5f93,
+	0x082f63b7, 0xfa44e0b4, 0xe9141340, 0x1b7f9043,
+	0xcfb5f4a8, 0x3dde77ab, 0x2e8e845f, 0xdce5075c,
+	0x92a8fc17, 0x60c37f14, 0x73938ce0, 0x81f80fe3,
+	0x55326b08, 0xa759e80b, 0xb4091bff, 0x466298fc,
+	0x1871a4d8, 0xea1a27db, 0xf94ad42f, 0x0b21572c,
+	0xdfeb33c7, 0x2d80b0c4, 0x3ed04330, 0xccbbc033,
+	0xa24bb5a6, 0x502036a5, 0x4370c551, 0xb11b4652,
+	0x65d122b9, 0x97baa1ba, 0x84ea524e, 0x7681d14d,
+	0x2892ed69, 0xdaf96e6a, 0xc9a99d9e, 0x3bc21e9d,
+	0xef087a76, 0x1d63f975, 0x0e330a81, 0xfc588982,
+	0xb21572c9, 0x407ef1ca, 0x532e023e, 0xa145813d,
+	0x758fe5d6, 0x87e466d5, 0x94b49521, 0x66df1622,
+	0x38cc2a06, 0xcaa7a905, 0xd9f75af1, 0x2b9cd9f2,
+	0xff56bd19, 0x0d3d3e1a, 0x1e6dcdee, 0xec064eed,
+	0xc38d26c4, 0x31e6a5c7, 0x22b65633, 0xd0ddd530,
+	0x0417b1db, 0xf67c32d8, 0xe52cc12c, 0x1747422f,
+	0x49547e0b, 0xbb3ffd08, 0xa86f0efc, 0x5a048dff,
+	0x8ecee914, 0x7ca56a17, 0x6ff599e3, 0x9d9e1ae0,
+	0xd3d3e1ab, 0x21b862a8, 0x32e8915c, 0xc083125f,
+	0x144976b4, 0xe622f5b7, 0xf5720643, 0x07198540,
+	0x590ab964, 0xab613a67, 0xb831c993, 0x4a5a4a90,
+	0x9e902e7b, 0x6cfbad78, 0x7fab5e8c, 0x8dc0dd8f,
+	0xe330a81a, 0x115b2b19, 0x020bd8ed, 0xf0605bee,
+	0x24aa3f05, 0xd6c1bc06, 0xc5914ff2, 0x37faccf1,
+	0x69e9f0d5, 0x9b8273d6, 0x88d28022, 0x7ab90321,
+	0xae7367ca, 0x5c18e4c9, 0x4f48173d, 0xbd23943e,
+	0xf36e6f75, 0x0105ec76, 0x12551f82, 0xe03e9c81,
+	0x34f4f86a, 0xc69f7b69, 0xd5cf889d, 0x27a40b9e,
+	0x79b737ba, 0x8bdcb4b9, 0x988c474d, 0x6ae7c44e,
+	0xbe2da0a5, 0x4c4623a6, 0x5f16d052, 0xad7d5351,
+};
+
+uint32_t tst_crc32c(uint8_t *buf, size_t buf_len)
+{
+	uint32_t crc = 0xffffffff;
+
+	while (buf_len--)
+		crc = crc32c_table[(crc ^ (*buf++)) & 0xff] ^ (crc >> 8);
+
+	return ~crc;
+}
-- 
1.7.1

[LTP] [PATCH v2 2/2] sctp_big_chunk: make INIT packet in the test

[Alexey Kodanev]

Since creating many different IP addresses and binding them
to the same SCTP socket is a time consuming process, prepare
SCTP INIT chunk in the test.

Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
---
v2: * the test doesn't support IPv6 fragmentation, TCONF in that case
    * add needs_root since we use a raw socket

 runtest/cve                             |    1 -
 testcases/network/sctp/sctp_big_chunk.c |  105 +++++++++++++++++++++++++++----
 2 files changed, 93 insertions(+), 13 deletions(-)

diff --git a/runtest/cve b/runtest/cve
index 1d9569a..2f4171c 100644
--- a/runtest/cve
+++ b/runtest/cve
@@ -33,4 +33,3 @@ cve-2017-17052 cve-2017-17052
 cve-2017-16939 cve-2017-16939
 cve-2017-17053 cve-2017-17053
 cve-2018-5803 sctp_big_chunk
-cve-2018-5803_2 sctp_big_chunk -a 10000
diff --git a/testcases/network/sctp/sctp_big_chunk.c b/testcases/network/sctp/sctp_big_chunk.c
index 55a2969..89c5e0d 100644
--- a/testcases/network/sctp/sctp_big_chunk.c
+++ b/testcases/network/sctp/sctp_big_chunk.c
@@ -24,12 +24,14 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
+#include <netinet/ip.h>
+#include <netinet/ip6.h>
 #include <netdb.h>
 #include <sys/syscall.h>
-#include <fcntl.h>
 
 #include "tst_test.h"
 #include "tst_safe_stdio.h"
+#include "tst_checksum.h"
 #include "lapi/netinet_in.h"
 #include "lapi/socket.h"
 #include "lapi/sctp.h"
@@ -38,6 +40,8 @@ static int port;
 static int sfd, cfd;
 static struct sockaddr_in6 rmt, loc;
 
+static uint8_t packet[IP_MAXPACKET];
+static int pkt_len;
 static char *addr_param;
 static int addr_num = 3273;
 
@@ -53,35 +57,108 @@ static void setup_server(void)
 	tst_res(TINFO, "sctp server listen on %d", port);
 
 	SAFE_LISTEN(sfd, 1);
+
+	srand(port);
+}
+
+static void update_packet_field(size_t *off, void *buf, size_t buf_len)
+{
+	memcpy(packet + *off, buf, buf_len);
+	*off += buf_len;
 }
 
 static void setup_client(void)
 {
-	struct sockaddr_in6 addr_buf[addr_num];
+	struct ip6_hdr ip6;
+	const size_t ip6_hdr_len = sizeof(ip6);
+	size_t cmn_hdr_off;
+	size_t off;
 	int i;
 
-	cfd = SAFE_SOCKET(AF_INET6, SOCK_STREAM, IPPROTO_SCTP);
+	memset(&ip6, 0, sizeof(ip6));
+	ip6.ip6_flow = htonl(6 << 28 | 2 << 20);
+	ip6.ip6_hops = 64;
+	ip6.ip6_nxt = IPPROTO_SCTP;
+	ip6.ip6_src.s6_addr[15] = 1;
+	ip6.ip6_dst.s6_addr[15] = 1;
 	rmt.sin6_family = AF_INET6;
 	rmt.sin6_addr = in6addr_loopback;
-	rmt.sin6_port = htons(port);
 
-	tst_res(TINFO, "bind %d additional IP addresses", addr_num);
+	/* SCTP common header */
+	off = ip6_hdr_len;
+
+	uint16_t src_port = htons(port - 1);
+	uint16_t dst_port = htons(port);
+	uint32_t vtag = 0;
+	uint32_t checksum = 0;
+
+	update_packet_field(&off, &src_port, 2);
+	update_packet_field(&off, &dst_port, 2);
+	update_packet_field(&off, &vtag, 4);
+	update_packet_field(&off, &checksum, 4);
+	cmn_hdr_off = off;
+
+	/* SCTP INIT chunk */
+	uint16_t chunk_len;
+
+	packet[off++] = 1;
+	packet[off++] = 0;
+	off += 2; /* chunk length, will be set in the end */
+
+	uint32_t init_tag = rand();
+	uint32_t rwnd = htonl(106496);
+	uint16_t outs = htons(10);
+	uint16_t ins = htons(65535);
+	uint32_t init_tsn = rand();
+
+	update_packet_field(&off, &init_tag, 4);
+	update_packet_field(&off, &rwnd, 4);
+	update_packet_field(&off, &outs, 2);
+	update_packet_field(&off, &ins, 2);
+	update_packet_field(&off, &init_tsn, 4);
 
-	memset(addr_buf, 0, sizeof(addr_buf));
+	/* SCTP optional parameter for IPv6 addresses */
+	uint16_t param_type = htons(6);
+	uint16_t param_len = htons(20);
+
+	/* IPv6(40) + SCTP_COMMON(12) + SCTP_CHUNK(20) + SCTP_OPT(65460)) */
 	for (i = 0; i < addr_num; ++i) {
-		addr_buf[i].sin6_family = AF_INET6;
-		addr_buf[i].sin6_addr = in6addr_loopback;
+		update_packet_field(&off, &param_type, 2);
+		update_packet_field(&off, &param_len, 2);
+		packet[off + 15] = 1;
+		off += 16;
 	}
+	pkt_len = off;
+
+	tst_res(TINFO, "set chunk length %zu", pkt_len - cmn_hdr_off);
+	chunk_len = htons(pkt_len - cmn_hdr_off);
+	memcpy(packet + cmn_hdr_off + 2, &chunk_len, 2);
+
+	/* set checksum for SCTP: common header + INIT chunk */
+	uint32_t csum = tst_crc32c(packet + ip6_hdr_len, pkt_len - ip6_hdr_len);
+
+	memcpy(packet + ip6_hdr_len + 8, &csum, 4);
+
+	ip6.ip6_plen = htons(pkt_len - ip6_hdr_len);
+	memcpy(packet, &ip6, ip6_hdr_len);
 
-	SAFE_SETSOCKOPT(cfd, SOL_SCTP, SCTP_SOCKOPT_BINDX_ADD, addr_buf,
-			sizeof(addr_buf));
+	cfd = SAFE_SOCKET(AF_INET6, SOCK_RAW, IPPROTO_RAW);
 }
 
+static const char mtu_path[] = "/sys/class/net/lo/mtu";
+static const unsigned int max_mtu = 65535;
+static unsigned int mtu;
+
 static void setup(void)
 {
 	if (tst_parse_int(addr_param, &addr_num, 1, INT_MAX))
 		tst_brk(TBROK, "wrong address number '%s'", addr_param);
 
+	/* We don't fragment IPv6 packet here yet, check that MTU is 65535 */
+	SAFE_FILE_SCANF(mtu_path, "%d", &mtu);
+	if (mtu < max_mtu)
+		tst_brk(TCONF, "Test needs that 'lo' MTU has %d", max_mtu);
+
 	setup_server();
 	setup_client();
 }
@@ -89,6 +166,7 @@ static void setup(void)
 static void run(void)
 {
 	int pid = SAFE_FORK();
+	int i;
 
 	if (!pid) {
 		struct sockaddr_in6 addr6;
@@ -99,8 +177,10 @@ static void run(void)
 		exit(0);
 	}
 
-	fcntl(cfd, F_SETFL, O_NONBLOCK);
-	connect(cfd, (struct sockaddr *)&rmt, sizeof(rmt));
+	for (i = 0; i < 3; ++i) {
+		SAFE_SENDTO(1, cfd, packet, pkt_len, 0,
+			(struct sockaddr *)&rmt, sizeof(rmt));
+	}
 
 	SAFE_KILL(pid, SIGKILL);
 	SAFE_WAITPID(pid, NULL, 0);
@@ -114,6 +194,7 @@ static struct tst_option options[] = {
 };
 
 static struct tst_test test = {
+	.needs_root = 1,
 	.setup = setup,
 	.forks_child = 1,
 	.test_all = run,
-- 
1.7.1

[LTP] [PATCH v2 2/2] sctp_big_chunk: make INIT packet in the test

[Xiao Yang]

Hi Alexey,

This patch set works well on my environment, and it looks good to me.

Thanks,
Xiao Yang
On 2018/04/24 21:04, Alexey Kodanev wrote:
> Since creating many different IP addresses and binding them
> to the same SCTP socket is a time consuming process, prepare
> SCTP INIT chunk in the test.
>
> Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
> ---
> v2: * the test doesn't support IPv6 fragmentation, TCONF in that case
>     * add needs_root since we use a raw socket
>
>  runtest/cve                             |    1 -
>  testcases/network/sctp/sctp_big_chunk.c |  105 +++++++++++++++++++++++++++----
>  2 files changed, 93 insertions(+), 13 deletions(-)
>
> diff --git a/runtest/cve b/runtest/cve
> index 1d9569a..2f4171c 100644
> --- a/runtest/cve
> +++ b/runtest/cve
> @@ -33,4 +33,3 @@ cve-2017-17052 cve-2017-17052
>  cve-2017-16939 cve-2017-16939
>  cve-2017-17053 cve-2017-17053
>  cve-2018-5803 sctp_big_chunk
> -cve-2018-5803_2 sctp_big_chunk -a 10000
> diff --git a/testcases/network/sctp/sctp_big_chunk.c b/testcases/network/sctp/sctp_big_chunk.c
> index 55a2969..89c5e0d 100644
> --- a/testcases/network/sctp/sctp_big_chunk.c
> +++ b/testcases/network/sctp/sctp_big_chunk.c
> @@ -24,12 +24,14 @@
>  #include <sys/types.h>
>  #include <sys/socket.h>
>  #include <netinet/in.h>
> +#include <netinet/ip.h>
> +#include <netinet/ip6.h>
>  #include <netdb.h>
>  #include <sys/syscall.h>
> -#include <fcntl.h>
>  
>  #include "tst_test.h"
>  #include "tst_safe_stdio.h"
> +#include "tst_checksum.h"
>  #include "lapi/netinet_in.h"
>  #include "lapi/socket.h"
>  #include "lapi/sctp.h"
> @@ -38,6 +40,8 @@ static int port;
>  static int sfd, cfd;
>  static struct sockaddr_in6 rmt, loc;
>  
> +static uint8_t packet[IP_MAXPACKET];
> +static int pkt_len;
>  static char *addr_param;
>  static int addr_num = 3273;
>  
> @@ -53,35 +57,108 @@ static void setup_server(void)
>  	tst_res(TINFO, "sctp server listen on %d", port);
>  
>  	SAFE_LISTEN(sfd, 1);
> +
> +	srand(port);
> +}
> +
> +static void update_packet_field(size_t *off, void *buf, size_t buf_len)
> +{
> +	memcpy(packet + *off, buf, buf_len);
> +	*off += buf_len;
>  }
>  
>  static void setup_client(void)
>  {
> -	struct sockaddr_in6 addr_buf[addr_num];
> +	struct ip6_hdr ip6;
> +	const size_t ip6_hdr_len = sizeof(ip6);
> +	size_t cmn_hdr_off;
> +	size_t off;
>  	int i;
>  
> -	cfd = SAFE_SOCKET(AF_INET6, SOCK_STREAM, IPPROTO_SCTP);
> +	memset(&ip6, 0, sizeof(ip6));
> +	ip6.ip6_flow = htonl(6 << 28 | 2 << 20);
> +	ip6.ip6_hops = 64;
> +	ip6.ip6_nxt = IPPROTO_SCTP;
> +	ip6.ip6_src.s6_addr[15] = 1;
> +	ip6.ip6_dst.s6_addr[15] = 1;
>  	rmt.sin6_family = AF_INET6;
>  	rmt.sin6_addr = in6addr_loopback;
> -	rmt.sin6_port = htons(port);
>  
> -	tst_res(TINFO, "bind %d additional IP addresses", addr_num);
> +	/* SCTP common header */
> +	off = ip6_hdr_len;
> +
> +	uint16_t src_port = htons(port - 1);
> +	uint16_t dst_port = htons(port);
> +	uint32_t vtag = 0;
> +	uint32_t checksum = 0;
> +
> +	update_packet_field(&off, &src_port, 2);
> +	update_packet_field(&off, &dst_port, 2);
> +	update_packet_field(&off, &vtag, 4);
> +	update_packet_field(&off, &checksum, 4);
> +	cmn_hdr_off = off;
> +
> +	/* SCTP INIT chunk */
> +	uint16_t chunk_len;
> +
> +	packet[off++] = 1;
> +	packet[off++] = 0;
> +	off += 2; /* chunk length, will be set in the end */
> +
> +	uint32_t init_tag = rand();
> +	uint32_t rwnd = htonl(106496);
> +	uint16_t outs = htons(10);
> +	uint16_t ins = htons(65535);
> +	uint32_t init_tsn = rand();
> +
> +	update_packet_field(&off, &init_tag, 4);
> +	update_packet_field(&off, &rwnd, 4);
> +	update_packet_field(&off, &outs, 2);
> +	update_packet_field(&off, &ins, 2);
> +	update_packet_field(&off, &init_tsn, 4);
>  
> -	memset(addr_buf, 0, sizeof(addr_buf));
> +	/* SCTP optional parameter for IPv6 addresses */
> +	uint16_t param_type = htons(6);
> +	uint16_t param_len = htons(20);
> +
> +	/* IPv6(40) + SCTP_COMMON(12) + SCTP_CHUNK(20) + SCTP_OPT(65460)) */
>  	for (i = 0; i < addr_num; ++i) {
> -		addr_buf[i].sin6_family = AF_INET6;
> -		addr_buf[i].sin6_addr = in6addr_loopback;
> +		update_packet_field(&off, &param_type, 2);
> +		update_packet_field(&off, &param_len, 2);
> +		packet[off + 15] = 1;
> +		off += 16;
>  	}
> +	pkt_len = off;
> +
> +	tst_res(TINFO, "set chunk length %zu", pkt_len - cmn_hdr_off);
> +	chunk_len = htons(pkt_len - cmn_hdr_off);
> +	memcpy(packet + cmn_hdr_off + 2, &chunk_len, 2);
> +
> +	/* set checksum for SCTP: common header + INIT chunk */
> +	uint32_t csum = tst_crc32c(packet + ip6_hdr_len, pkt_len - ip6_hdr_len);
> +
> +	memcpy(packet + ip6_hdr_len + 8, &csum, 4);
> +
> +	ip6.ip6_plen = htons(pkt_len - ip6_hdr_len);
> +	memcpy(packet, &ip6, ip6_hdr_len);
>  
> -	SAFE_SETSOCKOPT(cfd, SOL_SCTP, SCTP_SOCKOPT_BINDX_ADD, addr_buf,
> -			sizeof(addr_buf));
> +	cfd = SAFE_SOCKET(AF_INET6, SOCK_RAW, IPPROTO_RAW);
>  }
>  
> +static const char mtu_path[] = "/sys/class/net/lo/mtu";
> +static const unsigned int max_mtu = 65535;
> +static unsigned int mtu;
> +
>  static void setup(void)
>  {
>  	if (tst_parse_int(addr_param, &addr_num, 1, INT_MAX))
>  		tst_brk(TBROK, "wrong address number '%s'", addr_param);
>  
> +	/* We don't fragment IPv6 packet here yet, check that MTU is 65535 */
> +	SAFE_FILE_SCANF(mtu_path, "%d", &mtu);
> +	if (mtu < max_mtu)
> +		tst_brk(TCONF, "Test needs that 'lo' MTU has %d", max_mtu);
> +
>  	setup_server();
>  	setup_client();
>  }
> @@ -89,6 +166,7 @@ static void setup(void)
>  static void run(void)
>  {
>  	int pid = SAFE_FORK();
> +	int i;
>  
>  	if (!pid) {
>  		struct sockaddr_in6 addr6;
> @@ -99,8 +177,10 @@ static void run(void)
>  		exit(0);
>  	}
>  
> -	fcntl(cfd, F_SETFL, O_NONBLOCK);
> -	connect(cfd, (struct sockaddr *)&rmt, sizeof(rmt));
> +	for (i = 0; i < 3; ++i) {
> +		SAFE_SENDTO(1, cfd, packet, pkt_len, 0,
> +			(struct sockaddr *)&rmt, sizeof(rmt));
> +	}
>  
>  	SAFE_KILL(pid, SIGKILL);
>  	SAFE_WAITPID(pid, NULL, 0);
> @@ -114,6 +194,7 @@ static struct tst_option options[] = {
>  };
>  
>  static struct tst_test test = {
> +	.needs_root = 1,
>  	.setup = setup,
>  	.forks_child = 1,
>  	.test_all = run,