On Tue, Mar 7, 2023 at 8:50 AM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab@nec.com> wrote:
Hi Lianbo,

thank you for the update.

For a few details..

On 2023/03/03 16:23, Lianbo Jiang wrote:
> Currently, the "net" command displays only the IPv4 address of a network
> interface, it doesn't support outputting IPv6 address yet. For example:
>
> Without the patch:
>    crash> net
>       NET_DEVICE     NAME   IP ADDRESS(ES)
>    ffff8d01b1205000  lo     127.0.0.1
>    ffff8d0087e40000  eno1   192.168.122.2
>
> With the patch:
>    crash> net
>       NET_DEVICE     NAME       IP ADDRESS(ES)
>    ffff8d01b1205000  lo         127.0.0.1, ::1
>    ffff8d0087e40000  eno1       192.168.122.2, xxxx:xx:x:xxxx:xxxx:xxx:xxxx:xxxx, yyyy::yyyy:yyy:yyyy:yyyy
>
> Related kernel commit:
> 502a2ffd7376 ("ipv6: convert idev_list to list macros")
>
> Reported-by: Buland Kumar Singh <bsingh@redhat.com>
> Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
> ---
>   defs.h    |   6 +++
>   net.c     | 109 +++++++++++++++++++++++++++++++++++++++++++++++++-----
>   symbols.c |   6 +++
>   3 files changed, 112 insertions(+), 9 deletions(-)
>
> diff --git a/defs.h b/defs.h
> index e76af3c78b69..1f2cf6e0ce01 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -2208,6 +2208,12 @@ struct offset_table {                    /* stash of commonly-used offsets */
>       long sock_common_skc_v6_daddr;
>       long sock_common_skc_v6_rcv_saddr;
>       long inactive_task_frame_bp;
> +     long net_device_ip6_ptr;
> +     long inet6_dev_addr_list;
> +     long inet6_ifaddr_addr;
> +     long inet6_ifaddr_if_list;
> +     long inet6_ifaddr_if_next;
> +     long in6_addr_in6_u;
>   };
>   
>   struct size_table {         /* stash of commonly-used sizes */
> diff --git a/net.c b/net.c
> index aa445ab7ee13..6bca2a5d0098 100644
> --- a/net.c
> +++ b/net.c
> @@ -71,6 +71,7 @@ static void print_neighbour_q(ulong, int);
>   static void get_netdev_info(ulong, struct devinfo *);
>   static void get_device_name(ulong, char *);
>   static long get_device_address(ulong, char **, long);
> +static void get_device_ip6_address(ulong, char **, long);
>   static void get_sock_info(ulong, char *);
>   static void dump_arp(void);
>   static void arp_state_to_flags(unsigned char);
> @@ -114,6 +115,13 @@ net_init(void)
>               net->dev_ip_ptr = MEMBER_OFFSET_INIT(net_device_ip_ptr,
>                       "net_device", "ip_ptr");
>               MEMBER_OFFSET_INIT(net_device_dev_list, "net_device", "dev_list");
> +             MEMBER_OFFSET_INIT(net_device_ip6_ptr, "net_device", "ip6_ptr");
> +             MEMBER_OFFSET_INIT(inet6_dev_addr_list, "inet6_dev", "addr_list");
> +             MEMBER_OFFSET_INIT(inet6_ifaddr_addr, "inet6_ifaddr", "addr");
> +             MEMBER_OFFSET_INIT(inet6_ifaddr_if_list, "inet6_ifaddr", "if_list");
> +             MEMBER_OFFSET_INIT(inet6_ifaddr_if_next, "inet6_ifaddr", "if_next");
> +             MEMBER_OFFSET_INIT(in6_addr_in6_u, "in6_addr", "in6_u");
> +
>               MEMBER_OFFSET_INIT(net_dev_base_head, "net", "dev_base_head");
>               ARRAY_LENGTH_INIT(net->net_device_name_index,
>                       net_device_name, "net_device.name", NULL, sizeof(char));
> @@ -466,7 +474,7 @@ show_net_devices(ulong task)
>       buf = GETBUF(buflen);
>       flen = MAX(VADDR_PRLEN, strlen(net->netdevice));
>   
> -     fprintf(fp, "%s  NAME   IP ADDRESS(ES)\n",
> +     fprintf(fp, "%s  NAME       IP ADDRESS(ES)\n",
>               mkstring(upper_case(net->netdevice, buf),
>                       flen, CENTER|LJUST, NULL));
>   
> @@ -475,9 +483,10 @@ show_net_devices(ulong task)
>                       mkstring(buf, flen, CENTER|RJUST|LONG_HEX, MKSTR(next)));
>   
>               get_device_name(next, buf);
> -             fprintf(fp, "%-6s ", buf);
> +             fprintf(fp, "%-10s ", buf);
>   
> -             buflen = get_device_address(next, &buf, buflen);
> +             get_device_address(next, &buf, buflen);
> +             get_device_ip6_address(next, &buf, buflen);
>               fprintf(fp, "%s\n", buf);
>   
>               readmem(next+net->dev_next, KVADDR, &next,
> @@ -503,7 +512,7 @@ show_net_devices_v2(ulong task)
>       buf = GETBUF(buflen);
>       flen = MAX(VADDR_PRLEN, strlen(net->netdevice));
>   
> -     fprintf(fp, "%s  NAME   IP ADDRESS(ES)\n",
> +     fprintf(fp, "%s  NAME       IP ADDRESS(ES)\n",
>               mkstring(upper_case(net->netdevice, buf),
>                       flen, CENTER|LJUST, NULL));
>   
> @@ -528,9 +537,10 @@ show_net_devices_v2(ulong task)
>                       MKSTR(ld->list_ptr[i])));
>   
>               get_device_name(ld->list_ptr[i], buf);
> -             fprintf(fp, "%-6s ", buf);
> +             fprintf(fp, "%-10s ", buf);
>   
> -             buflen = get_device_address(ld->list_ptr[i], &buf, buflen);
> +             get_device_address(ld->list_ptr[i], &buf, buflen);
> +             get_device_ip6_address(ld->list_ptr[i], &buf, buflen);
>               fprintf(fp, "%s\n", buf);
>       }
>       
> @@ -556,7 +566,7 @@ show_net_devices_v3(ulong task)
>       buf = GETBUF(buflen);
>       flen = MAX(VADDR_PRLEN, strlen(net->netdevice));
>   
> -     fprintf(fp, "%s  NAME   IP ADDRESS(ES)\n",
> +     fprintf(fp, "%s  NAME       IP ADDRESS(ES)\n",
>               mkstring(upper_case(net->netdevice, buf),
>                       flen, CENTER|LJUST, NULL));
>   
> @@ -591,9 +601,10 @@ show_net_devices_v3(ulong task)
>                       MKSTR(ld->list_ptr[i])));
>   
>               get_device_name(ld->list_ptr[i], buf);
> -             fprintf(fp, "%-6s ", buf);
> +             fprintf(fp, "%-10s ", buf);
>   
> -             buflen = get_device_address(ld->list_ptr[i], &buf, buflen);
> +             get_device_address(ld->list_ptr[i], &buf, buflen);
> +             get_device_ip6_address(ld->list_ptr[i], &buf, buflen);
>               fprintf(fp, "%s\n", buf);
>       }
>       
> @@ -925,6 +936,86 @@ get_device_address(ulong devaddr, char **bufp, long buflen)
>       return buflen;
>   }
>   
> +static void
> +get_device_ip6_address(ulong devaddr, char **bufp, long buflen)
> +{
> +     ulong ip6_ptr = 0, pos = 0, bufsize = buflen, addr = 0;
> +     struct in6_addr ip6_addr;
> +     char *buf;
> +     char str[INET6_ADDRSTRLEN + 1] = {0};
> +     char buffer[INET6_ADDRSTRLEN + 4] = {0};

What are the +1 and +4 for?


I noticed that the size of INET6_ADDRSTRLEN is 48 in kernel code as below:

--- a/include/linux/inet.h
+++ b/include/linux/inet.h
+/*
+ * These mimic similar macros defined in user-space for inet_ntop(3).
+ * See /usr/include/netinet/in.h .
+ */
+#define INET_ADDRSTRLEN                (16)
+#define INET6_ADDRSTRLEN       (48)


And, the size of INET6_ADDRSTRLEN is 46 in my machine as below:

# cat /usr/include/netinet/in.h |grep INET6_ADDRSTRLEN
#define INET6_ADDRSTRLEN 46


The rfc2460 said that the IPv6 increases the IP address size from 32 bits to 128 bits.

crash> struct in6_addr
struct in6_addr {
    union {
        __u8 u6_addr8[16];
        __be16 u6_addr16[8];
        __be32 u6_addr32[4];
    } in6_u;
}
SIZE: 16

Given that, maybe they should be defined like this?

+     char str[INET6_ADDRSTRLEN + 2] = {0};
+     char buffer[INET6_ADDRSTRLEN + 2 + 2] = {0};

 Not sure what's the best way for this case.

Looking at the example in the man page of inet_pton(3), INET6_ADDRSTRLEN
seems enough for the str and contains a null char.  The buffer can have
a comma and a space (", ") so +2 is enough?  i.e.

   char str[INET6_ADDRSTRLEN] = {0};
   char buffer[INET6_ADDRSTRLEN + 2] = {0};


> +     uint len = 0;
> +
> +     buf = *bufp;
> +     pos = strlen(buf);

Ah nicely done :)

> +
> +     readmem(devaddr + OFFSET(net_device_ip6_ptr), KVADDR,
> +             &ip6_ptr, sizeof(ulong), "ip6_ptr", FAULT_ON_ERROR);
> +
> +     if (!ip6_ptr)
> +             return;
> +
> +     if (VALID_MEMBER(inet6_ifaddr_if_list)) {
> +             struct list_data list_data, *ld;
> +             ulong cnt = 0, i;
> +
> +             ld = &list_data;
> +             BZERO(ld, sizeof(struct list_data));
> +             ld->flags |= LIST_ALLOCATE;
> +             ld->start = ip6_ptr + OFFSET(inet6_dev_addr_list);
> +             cnt = do_list(ld);
> +
> +             for (i = 1; i < cnt; i++) {
> +
> +                     addr = ld->list_ptr[i] + OFFSET(inet6_ifaddr_addr);

> +                     addr -= OFFSET(inet6_ifaddr_if_list);

The above code is easy to understand, because it actually imitates the container_of().

But if you would like to have the same style as show_net_devices_v2() and show_net_devices_v3(), that's also fine to me.

This line can be removed with ld->list_head_offset parameter?
i.e.

     ld->start = ip6_ptr + OFFSET(inet6_dev_addr_list);
+   ld->list_head_offset = OFFSET(inet6_ifaddr_if_list);
     cnt = do_list(ld);

> +                     readmem(addr + OFFSET(in6_addr_in6_u), KVADDR, &ip6_addr,
> +                             sizeof(struct in6_addr), "in6_addr.in6_u", FAULT_ON_ERROR);
> +
> +                     inet_ntop(AF_INET6, (void*)&ip6_addr, str, INET6_ADDRSTRLEN);
> +                     sprintf(buffer, "%s%s", pos ? ", " : "", str);
> +                     len = strlen(buffer);
> +                     if (pos + len >= bufsize) {
> +                             RESIZEBUF(*bufp, bufsize, bufsize + buflen);
> +                             buf = *bufp;
> +                             BZERO(buf + bufsize, buflen);
> +                             bufsize += buflen;
> +                     }
> +                     BCOPY(buffer, &buf[pos], len);
> +                     pos += len;
> +             }
> +
> +             FREEBUF(ld->list_ptr);
> +             return;
> +     }
> +

> +     /*
> +      * 502a2ffd7376 ("ipv6: convert idev_list to list macros")
> +      * v2.6.35-rc1~473^2~733
> +      */

This should be moved before the if block above?


Yes, you are right. I forgot to move it there.

Thanks.
Lianbo
 
> +     readmem(ip6_ptr + OFFSET(inet6_dev_addr_list), KVADDR,
> +             &addr, sizeof(void *), "inet6_dev.addr_list", FAULT_ON_ERROR);
> +
> +     while (addr) {
> +             readmem(addr + OFFSET(in6_addr_in6_u), KVADDR, &ip6_addr,
> +                     sizeof(struct in6_addr), "in6_addr.in6_u", FAULT_ON_ERROR);
> +             inet_ntop(AF_INET6, (void*)&ip6_addr, str, INET6_ADDRSTRLEN);
> +             sprintf(buffer, "%s%s", pos ? ", " : "", str);
> +             len = strlen(buffer);
> +
> +             if (pos + len >= bufsize) {
> +                     RESIZEBUF(*bufp, bufsize, bufsize + buflen);
> +                     buf = *bufp;
> +                     BZERO(buf + bufsize, buflen);
> +                     bufsize += buflen;
> +             }
> +             BCOPY(buffer, &buf[pos], len);
> +             pos += len;
> +             readmem(addr + OFFSET(inet6_ifaddr_if_next), KVADDR, &addr,
> +                     sizeof(void *), "inet6_ifaddr.if_next", FAULT_ON_ERROR);
> +     }
> +}
> +
>   /*
>    *  Get the family, type, local and destination address/port pairs.
>    */
> diff --git a/symbols.c b/symbols.c
> index a974fc9141a0..3efcdddfcadb 100644
> --- a/symbols.c
> +++ b/symbols.c
> @@ -9787,6 +9787,7 @@ dump_offset_table(char *spec, ulong makestruct)
>               OFFSET(net_device_addr_len));
>       fprintf(fp, "             net_device_ip_ptr: %ld\n",
>               OFFSET(net_device_ip_ptr));
> +     fprintf(fp, "            net_device_ip6_ptr: %ld\n", OFFSET(net_device_ip6_ptr));
>       fprintf(fp, "           net_device_dev_list: %ld\n",
>               OFFSET(net_device_dev_list));
>       fprintf(fp, "             net_dev_base_head: %ld\n",
> @@ -9839,6 +9840,11 @@ dump_offset_table(char *spec, ulong makestruct)
>           fprintf(fp, "                  inet_opt_num: %ld\n",
>               OFFSET(inet_opt_num));
>   
> +        fprintf(fp, "           inet6_dev_addr_list: %ld\n", OFFSET(inet6_dev_addr_list));
> +        fprintf(fp, "             inet6_ifaddr_addr: %ld\n", OFFSET(inet6_ifaddr_addr));
> +        fprintf(fp, "          inet6_ifaddr_if_list: %ld\n", OFFSET(inet6_ifaddr_if_list));
> +        fprintf(fp, "          inet6_ifaddr_if_next: %ld\n", OFFSET(inet6_ifaddr_if_next));
> +        fprintf(fp, "                in6_addr_in6_u: %ld\n", OFFSET(in6_addr_in6_u));
>           fprintf(fp, "          ipv6_pinfo_rcv_saddr: %ld\n",
>               OFFSET(ipv6_pinfo_rcv_saddr));
>           fprintf(fp, "              ipv6_pinfo_daddr: %ld\n",

Thanks, good!

Kazu