Daniel Lezcano wrote:
> The objective we have is to remove the fl_net field from the struct flowi.
>
> In the previous patch, we make the network namespace to go up to the
> dst_entry.
> This patch makes an example in how we can use the dst_entry/rtable combined
> with
> a container_of to retrieve the network namespace when we have the flowi
> parameter.
>
> One restriction is we should pass always a flowi parameter coming from a
> struct
> dst_entry.
this is an obfuscation IMHO. You use rtable instead of flowi, so
- rtable obtain flowi meaning and keeps original meaning
- stack usage in increased
So, for the case, I think it is better to have an additional parameter
on IP route output path. (There is a device on the input one).
Regards,
Den
>
> ---
> include/net/ip_fib.h | 3 -
> net/ipv4/route.c | 111
> ++++++++++++++++++++++++++-------------------------
> 2 files changed, 60 insertions(+), 54 deletions(-)
>
> Index: linux-2.6-netns/net/ipv4/route.c
> ===================================================================
> --- linux-2.6-netns.orig/net/ipv4/route.c
> +++ linux-2.6-netns/net/ipv4/route.c
> @@ -1788,15 +1788,18 @@ static int ip_route_input_slow(struct sk
> struct net *net = dev->nd_net;
> struct fib_result res;
> struct in_device *in_dev = in_dev_get(dev);
> - struct flowi fl = { .fl_net = net,
> - .nl_u = { .ip4_u =
> - { .daddr = daddr,
> - .saddr = saddr,
> - .tos = tos,
> - .scope = RT_SCOPE_UNIVERSE,
> - } },
> - .mark = skb->mark,
> - .iif = dev->ifindex };
> + struct rtable rt = {
> + .u.dst.net = net,
> + .fl = { .fl_net = net,
> + .nl_u = { .ip4_u =
> + { .daddr = daddr,
> + .saddr = saddr,
> + .tos = tos,
> + .scope = RT_SCOPE_UNIVERSE,
> + } },
> + .mark = skb->mark,
> + .iif = dev->ifindex },
> + };
> unsigned flags = 0;
> u32 itag = 0;
> struct rtable * rth;
> @@ -1832,7 +1835,7 @@ static int ip_route_input_slow(struct sk
> /*
> * Now we are ready to route packet.
> */
> - if ((err = fib_lookup(&fl, &res)) != 0) {
> + if ((err = fib_lookup(&rt.fl, &res)) != 0) {
> if (!IN_DEV_FORWARD(in_dev))
> goto e_hostunreach;
> goto no_route;
> @@ -1862,7 +1865,7 @@ static int ip_route_input_slow(struct sk
> if (res.type != RTN_UNICAST)
> goto martian_destination;
>
> - err = ip_mkroute_input(skb, &res, &fl, in_dev, daddr, saddr, tos);
> + err = ip_mkroute_input(skb, &res, &rt.fl, in_dev, daddr, saddr, tos);
> done:
> in_dev_put(in_dev);
> if (free_res)
> @@ -1898,7 +1901,6 @@ local_input:
> rth->u.dst.flags= DST_HOST;
> if (IN_DEV_CONF_GET(in_dev, NOPOLICY))
> rth->u.dst.flags |= DST_NOPOLICY;
> - rth->fl.fl_net = net;
> rth->fl.fl4_dst = daddr;
> rth->rt_dst = daddr;
> rth->fl.fl4_tos = tos;
> @@ -1923,7 +1925,7 @@ local_input:
> rth->rt_flags &= ~RTCF_LOCAL;
> }
> rth->rt_type = res.type;
> - hash = rt_hash(daddr, saddr, fl.iif);
> + hash = rt_hash(daddr, saddr, rt.fl.iif);
> err = rt_intern_hash(hash, rth, (struct rtable**)&skb->dst);
> goto done;
>
> @@ -2173,18 +2175,21 @@ static int ip_route_output_slow(struct r
> {
> u32 tos = RT_FL_TOS(oldflp);
> struct net *net = oldflp->fl_net;
> - struct flowi fl = { .fl_net = net,
> - .nl_u = { .ip4_u =
> - { .daddr = oldflp->fl4_dst,
> - .saddr = oldflp->fl4_src,
> - .tos = tos & IPTOS_RT_MASK,
> - .scope = ((tos & RTO_ONLINK) ?
> - RT_SCOPE_LINK :
> - RT_SCOPE_UNIVERSE),
> - } },
> - .mark = oldflp->mark,
> - .iif = net->loopback_dev->ifindex,
> - .oif = oldflp->oif };
> + struct rtable rt = {
> + .u.dst.net = net,
> + .fl = { .fl_net = net,
> + .nl_u = { .ip4_u =
> + { .daddr = oldflp->fl4_dst,
> + .saddr = oldflp->fl4_src,
> + .tos = tos & IPTOS_RT_MASK,
> + .scope = ((tos & RTO_ONLINK) ?
> + RT_SCOPE_LINK :
> + RT_SCOPE_UNIVERSE),
> + } },
> + .mark = oldflp->mark,
> + .iif = net->loopback_dev->ifindex,
> + .oif = oldflp->oif },
> + };
> struct fib_result res;
> unsigned flags = 0;
> struct net_device *dev_out = NULL;
> @@ -2234,7 +2239,7 @@ static int ip_route_output_slow(struct r
> Luckily, this hack is good workaround.
> */
>
> - fl.oif = dev_out->ifindex;
> + rt.fl.oif = dev_out->ifindex;
> goto make_route;
> }
> if (dev_out)
> @@ -2256,36 +2261,36 @@ static int ip_route_output_slow(struct r
> }
>
> if (LOCAL_MCAST(oldflp->fl4_dst) || oldflp->fl4_dst ==
> htonl(0xFFFFFFFF)) {
> - if (!fl.fl4_src)
> - fl.fl4_src = inet_select_addr(dev_out, 0,
> - RT_SCOPE_LINK);
> + if (!rt.fl.fl4_src)
> + rt.fl.fl4_src = inet_select_addr(dev_out, 0,
> + RT_SCOPE_LINK);
> goto make_route;
> }
> - if (!fl.fl4_src) {
> + if (!rt.fl.fl4_src) {
> if (MULTICAST(oldflp->fl4_dst))
> - fl.fl4_src = inet_select_addr(dev_out, 0,
> - fl.fl4_scope);
> + rt.fl.fl4_src = inet_select_addr(dev_out, 0,
> +
> rt.fl.fl4_scope);
> else if (!oldflp->fl4_dst)
> - fl.fl4_src = inet_select_addr(dev_out, 0,
> - RT_SCOPE_HOST);
> + rt.fl.fl4_src = inet_select_addr(dev_out, 0,
> + RT_SCOPE_HOST);
> }
> }
>
> - if (!fl.fl4_dst) {
> - fl.fl4_dst = fl.fl4_src;
> - if (!fl.fl4_dst)
> - fl.fl4_dst = fl.fl4_src = htonl(INADDR_LOOPBACK);
> + if (!rt.fl.fl4_dst) {
> + rt.fl.fl4_dst = rt.fl.fl4_src;
> + if (!rt.fl.fl4_dst)
> + rt.fl.fl4_dst = rt.fl.fl4_src = htonl(INADDR_LOOPBACK);
> if (dev_out)
> dev_put(dev_out);
> dev_out = net->loopback_dev;
> dev_hold(dev_out);
> - fl.oif = net->loopback_dev->ifindex;
> + rt.fl.oif = net->loopback_dev->ifindex;
> res.type = RTN_LOCAL;
> flags |= RTCF_LOCAL;
> goto make_route;
> }
>
> - if (fib_lookup(&fl, &res)) {
> + if (fib_lookup(&rt.fl, &res)) {
> res.fi = NULL;
> if (oldflp->oif) {
> /* Apparently, routing tables are wrong. Assume,
> @@ -2306,9 +2311,9 @@ static int ip_route_output_slow(struct r
> likely IPv6, but we do not.
> */
>
> - if (fl.fl4_src == 0)
> - fl.fl4_src = inet_select_addr(dev_out, 0,
> - RT_SCOPE_LINK);
> + if (rt.fl.fl4_src == 0)
> + rt.fl.fl4_src = inet_select_addr(dev_out, 0,
> + RT_SCOPE_LINK);
> res.type = RTN_UNICAST;
> goto make_route;
> }
> @@ -2320,13 +2325,13 @@ static int ip_route_output_slow(struct r
> free_res = 1;
>
> if (res.type == RTN_LOCAL) {
> - if (!fl.fl4_src)
> - fl.fl4_src = fl.fl4_dst;
> + if (!rt.fl.fl4_src)
> + rt.fl.fl4_src = rt.fl.fl4_dst;
> if (dev_out)
> dev_put(dev_out);
> dev_out = net->loopback_dev;
> dev_hold(dev_out);
> - fl.oif = dev_out->ifindex;
> + rt.fl.oif = dev_out->ifindex;
> if (res.fi)
> fib_info_put(res.fi);
> res.fi = NULL;
> @@ -2336,24 +2341,24 @@ static int ip_route_output_slow(struct r
>
> #ifdef CONFIG_IP_ROUTE_MULTIPATH
> if (res.fi->fib_nhs > 1 && fl.oif == 0)
> - fib_select_multipath(&fl, &res);
> + fib_select_multipath(&rt.fl, &res);
> else
> #endif
> - if (!res.prefixlen && res.type == RTN_UNICAST && !fl.oif)
> - fib_select_default(&fl, &res);
> + if (!res.prefixlen && res.type == RTN_UNICAST && !rt.fl.oif)
> + fib_select_default(&rt.fl, &res);
>
> - if (!fl.fl4_src)
> - fl.fl4_src = FIB_RES_PREFSRC(res);
> + if (!rt.fl.fl4_src)
> + rt.fl.fl4_src = FIB_RES_PREFSRC(res);
>
> if (dev_out)
> dev_put(dev_out);
> dev_out = FIB_RES_DEV(res);
> dev_hold(dev_out);
> - fl.oif = dev_out->ifindex;
> + rt.fl.oif = dev_out->ifindex;
>
>
> make_route:
> - err = ip_mkroute_output(rp, &res, &fl, oldflp, dev_out, flags);
> + err = ip_mkroute_output(rp, &res, &rt.fl, oldflp, dev_out, flags);
>
>
> if (free_res)
> Index: linux-2.6-netns/include/net/ip_fib.h
> ===================================================================
> --- linux-2.6-netns.orig/include/net/ip_fib.h
> +++ linux-2.6-netns/include/net/ip_fib.h
> @@ -173,7 +173,8 @@ static inline struct fib_table *fib_new_
>
> static inline int fib_lookup(const struct flowi *flp, struct fib_result *res)
> {
> - struct net *net = flp->fl_net;
> + struct rtable *rt = container_of(flp, struct rtable, fl);
> + struct net *net = rt->u.dst.net;
> struct fib_table *local_table = net->ip_fib_local_table;
> struct fib_table *main_table = net->ip_fib_main_table;
> if (local_table->tb_lookup(local_table, flp, res) &&
>
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