[PATCH] libiproute: fix filtering ip6 route by table id

[Denys Vlasenko]

On Sun, Feb 12, 2023 at 5:30 AM Yousong Zhou <yszhou4tech at gmail.com> wrote:
>
> Otherwise
>
>  - "ip -6 route show" shows routes from all tables
>  - "ip -6 route show table 200" shows nothing
>
> function                                             old     new   delta
> print_route                                         1962    1941     -21
> ------------------------------------------------------------------------------
> (add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-21)             Total: -21 bytes
>
> Signed-off-by: Yousong Zhou <yszhou4tech at gmail.com>
> ---
>  networking/libiproute/iproute.c | 10 +---------
>  1 file changed, 1 insertion(+), 9 deletions(-)
>
> diff --git a/networking/libiproute/iproute.c b/networking/libiproute/iproute.c
> index 5a972f8b2..cd77f642f 100644
> --- a/networking/libiproute/iproute.c
> +++ b/networking/libiproute/iproute.c
> @@ -111,15 +111,7 @@ static int FAST_FUNC print_route(const struct sockaddr_nl *who UNUSED_PARAM,
>                                 if (r->rtm_flags & RTM_F_CLONED) {
>                                         return 0;
>                                 }
> -                               if (G_filter.tb == RT_TABLE_LOCAL) {
> -                                       if (r->rtm_type != RTN_LOCAL) {
> -                                               return 0;
> -                                       }
> -                               } else if (G_filter.tb == RT_TABLE_MAIN) {
> -                                       if (r->rtm_type == RTN_LOCAL) {
> -                                               return 0;
> -                                       }
> -                               } else {
> +                               if (G_filter.tb != tid) {
>                                         return 0;
>                                 }
>                         }

The very same code exists in current iproute2 git tree.
Is it also buggy in the same way?

iproute.c
static int filter_nlmsg(struct nlmsghdr *n, struct rtattr **tb, int host_len)
{
        struct rtmsg *r = NLMSG_DATA(n);
        inet_prefix dst = { .family = r->rtm_family };
        inet_prefix src = { .family = r->rtm_family };
        inet_prefix via = { .family = r->rtm_family };
        inet_prefix prefsrc = { .family = r->rtm_family };
        __u32 table;
        static int ip6_multiple_tables;

        table = rtm_get_table(r, tb);

        if (preferred_family != AF_UNSPEC && r->rtm_family != preferred_family)
                return 0;

        if (r->rtm_family == AF_INET6 && table != RT_TABLE_MAIN)
                ip6_multiple_tables = 1;

        if (filter.cloned == !(r->rtm_flags & RTM_F_CLONED))
                return 0;

        if (r->rtm_family == AF_INET6 && !ip6_multiple_tables) {
                if (filter.tb) {
                        if (filter.tb == RT_TABLE_LOCAL) {
                                if (r->rtm_type != RTN_LOCAL)
                                        return 0;
                        } else if (filter.tb == RT_TABLE_MAIN) {
                                if (r->rtm_type == RTN_LOCAL)
                                        return 0;
                        } else {
                                return 0;
                        }
                }
        } else {
                if (filter.tb > 0 && filter.tb != table)
                        return 0;
        }