lib/tst_checksum: add crc32c checksum

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 <[email protected]>

---
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(-)

runtest/cve +0 -1

index 1d9569a..2f4171c 100644
@@ -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

testcases/network/sctp/sctp_big_chunk.c +93 -12

index 55a2969..89c5e0d 100644
@@ -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,