Fix for "net -s" option to show IPv6 addresses on Linux 3.13 and later

Currently, the "net -s" option fails to show IPv6 addresses and ports
for the SOURCE-PORT and DESTINATION-PORT columns on Linux 3.13 and later
kernels, which have kernel commit efe4208f47f907 ("ipv6: make lookups
simpler and faster").  For example:

  crash> net -s
  PID: 305524   TASK: ffff9bc449895580  CPU: 6    COMMAND: "sshd"
  FD      SOCKET            SOCK       FAMILY:TYPE SOURCE-PORT DESTINATION-PORT
   3 ffff9bc446e9a680 ffff9bc4455b5940 UNIX:DGRAM
   4 ffff9bc446e9c600 ffff9bc3b2b24e00 INET6:STREAM

With the patch:

  crash> net -s
  PID: 305524   TASK: ffff9bc449895580  CPU: 6    COMMAND: "sshd"
  FD      SOCKET            SOCK       FAMILY:TYPE SOURCE-PORT DESTINATION-PORT
   3 ffff9bc446e9a680 ffff9bc4455b5940 UNIX:DGRAM
   4 ffff9bc446e9c600 ffff9bc3b2b24e00 INET6:STREAM xxxx:xx:x:xxxx:xxxx:xxxx:xxxx:xxxx-22 yyyy:yy:y:yyyy:yyyy:yyyy:yyyy:yyyy-44870

Reported-by: Buland Kumar Singh <bsingh@redhat.com>
Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
Signed-off-by: Kazuhito Hagio <k-hagio-ab@nec.com>

defs.h

@@ -2204,6 +2204,9 @@ struct offset_table {                    /* stash of commonly-used offsets */
 	long maple_range_64_slot;
 	long maple_metadata_end;
 	long maple_metadata_gap;
+	long sock_sk_common;
+	long sock_common_skc_v6_daddr;
+	long sock_common_skc_v6_rcv_saddr;
 };
 
 struct size_table {         /* stash of commonly-used sizes */

net.c

@@ -199,6 +199,9 @@ net_init(void)
 			MEMBER_OFFSET_INIT(sock_common_skc_family,
 				"sock_common", "skc_family");
 			MEMBER_OFFSET_INIT(sock_sk_type, "sock", "sk_type");
+			MEMBER_OFFSET_INIT(sock_sk_common, "sock", "__sk_common");
+			MEMBER_OFFSET_INIT(sock_common_skc_v6_daddr, "sock_common", "skc_v6_daddr");
+			MEMBER_OFFSET_INIT(sock_common_skc_v6_rcv_saddr, "sock_common", "skc_v6_rcv_saddr");
 			/*
 			 *  struct inet_sock {
         		 *	struct sock       sk;
@@ -1104,12 +1107,19 @@ get_sock_info(ulong sock, char *buf)
 		break;
 
 	case SOCK_V2:
-		if (INVALID_MEMBER(ipv6_pinfo_rcv_saddr) ||
-		    INVALID_MEMBER(ipv6_pinfo_daddr))
+		if (VALID_MEMBER(ipv6_pinfo_rcv_saddr) &&
+		    VALID_MEMBER(ipv6_pinfo_daddr)) {
+			ipv6_rcv_saddr = ipv6_pinfo + OFFSET(ipv6_pinfo_rcv_saddr);
+			ipv6_daddr = ipv6_pinfo + OFFSET(ipv6_pinfo_daddr);
+		} else if (VALID_MEMBER(sock_sk_common) &&
+			   VALID_MEMBER(sock_common_skc_v6_daddr) &&
+			   VALID_MEMBER(sock_common_skc_v6_rcv_saddr)) {
+			ipv6_rcv_saddr = sock + OFFSET(sock_sk_common) + OFFSET(sock_common_skc_v6_rcv_saddr);
+			ipv6_daddr = sock + OFFSET(sock_sk_common) + OFFSET(sock_common_skc_v6_daddr);
+		} else {
+			sprintf(&buf[strlen(buf)], "%s", "(cannot get IPv6 addresses)");
 			break;
-
-        	ipv6_rcv_saddr = ipv6_pinfo + OFFSET(ipv6_pinfo_rcv_saddr);
-		ipv6_daddr = ipv6_pinfo + OFFSET(ipv6_pinfo_daddr);
+		}
 
 		if (!readmem(ipv6_rcv_saddr, KVADDR, u6_addr16_src, SIZE(in6_addr),
                     "ipv6_rcv_saddr buffer", QUIET|RETURN_ON_ERROR))

symbols.c

@@ -9818,8 +9818,11 @@ dump_offset_table(char *spec, ulong makestruct)
 
         fprintf(fp, "                  sock_sk_type: %ld\n", 
 		OFFSET(sock_sk_type));
+	fprintf(fp, "                sock_sk_common: %ld\n", OFFSET(sock_sk_common));
         fprintf(fp, "        sock_common_skc_family: %ld\n", 
 		OFFSET(sock_common_skc_family));
+	fprintf(fp, "      sock_common_skc_v6_daddr: %ld\n", OFFSET(sock_common_skc_v6_daddr));
+	fprintf(fp, "  sock_common_skc_v6_rcv_saddr: %ld\n", OFFSET(sock_common_skc_v6_rcv_saddr));
 	fprintf(fp, "        socket_alloc_vfs_inode: %ld\n",
 		OFFSET(socket_alloc_vfs_inode));
         fprintf(fp, "                inet_sock_inet: %ld\n",