| Message ID | 20210301005318.8959-2-henry.shen@alliedtelesis.co.nz (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net:ipv4: Packet is not forwarded if bc_forwarding not configured on ingress interface | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Guessed tree name to be net-next |
| netdev/subject_prefix | warning | Target tree name not specified in the subject |
| netdev/cc_maintainers | success | CCed 5 of 5 maintainers |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 5 this patch: 5 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 38 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 5 this patch: 5 |
| netdev/header_inline | success | Link |
| netdev/stable | success | Stable not CCed |
On 2/28/21 5:53 PM, Henry Shen wrote: > When an IPv4 packet with a destination address of broadcast is received > on an ingress interface, it will not be forwarded out of the egress > interface if the ingress interface is not configured with bc_forwarding > but the egress interface is. If both the ingress and egress interfaces > are configured with bc_forwarding, the packet can be forwarded > successfully. > > This patch is to be inline with Cisco's implementation that packet can be > forwarded if ingress interface is NOT configured with bc_forwarding, > but egress interface is. > In Linux, forwarding decisions are made based on the ingress device, not the egress device.
diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 02d81d79deeb..d082b199b8c6 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -2101,6 +2101,8 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr, struct rtable *rth; struct flowi4 fl4; bool do_cache = true; + struct in_device *out_dev; + int rcv_local = 0; /* IP on this device is disabled. */ @@ -2176,12 +2178,20 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr, } if (res->type == RTN_BROADCAST) { + out_dev = in_dev_get(FIB_RES_DEV(*res)); + if (!out_dev) + goto out; + + if (in_dev == out_dev) + rcv_local = 1; + in_dev_put(out_dev); if (IN_DEV_BFORWARD(in_dev)) goto make_route; /* not do cache if bc_forwarding is enabled */ if (IPV4_DEVCONF_ALL(net, BC_FORWARDING)) do_cache = false; - goto brd_input; + if (rcv_local) + goto brd_input; } if (res->type == RTN_LOCAL) { @@ -2197,7 +2207,8 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr, goto no_route; } if (res->type != RTN_UNICAST) - goto martian_destination; + if (res->type != RTN_BROADCAST) + goto martian_destination; make_route: err = ip_mkroute_input(skb, res, in_dev, daddr, saddr, tos, flkeys);
When an IPv4 packet with a destination address of broadcast is received on an ingress interface, it will not be forwarded out of the egress interface if the ingress interface is not configured with bc_forwarding but the egress interface is. If both the ingress and egress interfaces are configured with bc_forwarding, the packet can be forwarded successfully. This patch is to be inline with Cisco's implementation that packet can be forwarded if ingress interface is NOT configured with bc_forwarding, but egress interface is. Signed-off-by: Henry Shen <henry.shen@alliedtelesis.co.nz> --- net/ipv4/route.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-)