Re: [PATCH v2 iproute2-next 4/4] bridge: fdb: enable FDB blackhole feature

On Tue, Oct 04, 2022 at 05:20:36PM +0200, Hans Schultz wrote:

Block traffic to a specific host with the command: bridge fdb add <MAC> vlan <vid> dev br0 blackhole

Blackhole FDB entries can be added, deleted and replaced with ordinary FDB entries.

Example with output:

$ bridge fdb add 10:10:10:10:10:10 dev br0 blackhole $ bridge -d fdb show dev br0 10:10:10:10:10:10 vlan 1 blackhole master br0 permanent 10:10:10:10:10:10 blackhole master br0 permanent $ bridge -d -j -p fdb show dev br0 [ { "mac": "10:10:10:10:10:10", "vlan": 1, "flags": [ "blackhole" ], "master": "br0", "state": "permanent" },{ "mac": "10:10:10:10:10:10", "flags": [ "blackhole" ], "master": "br0", "state": "permanent" } ]

Signed-off-by: Hans Schultz netdev@kapio-technology.com

bridge/fdb.c | 13 ++++++++++++- man/man8/bridge.8 | 12 ++++++++++++ 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/bridge/fdb.c b/bridge/fdb.c index f1f0a5bb..1c8c50a8 100644 --- a/bridge/fdb.c +++ b/bridge/fdb.c @@ -38,7 +38,7 @@ static void usage(void) fprintf(stderr, "Usage: bridge fdb { add | append | del | replace } ADDR dev DEV\n" " [ self ] [ master ] [ use ] [ router ] [ extern_learn ]\n"

• "              [ sticky ] [ local | static | dynamic ] [ vlan VID ]\n"
  

• "              [ sticky ] [ local | static | dynamic ] [ blackhole ] [ vlan VID ]\n"
  

  " { [ dst IPADDR ] [ port PORT] [ vni VNI ] | [ nhid NHID ] }\n" " [ via DEV ] [ src_vni VNI ]\n" " bridge fdb [ show [ br BRDEV ] [ brport DEV ] [ vlan VID ]\n"

@@ -116,6 +116,9 @@ static void fdb_print_flags(FILE *fp, unsigned int flags, __u8 ext_flags) if (flags & NTF_STICKY) print_string(PRINT_ANY, NULL, "%s ", "sticky");

• if (ext_flags & NTF_EXT_BLACKHOLE)

• print_string(PRINT_ANY, NULL, "%s ", "blackhole");
  

• if (ext_flags & NTF_EXT_LOCKED) print_string(PRINT_ANY, NULL, "%s ", "locked");

@@ -421,6 +424,7 @@ static int fdb_modify(int cmd, int flags, int argc, char **argv) char *endptr; short vid = -1; __u32 nhid = 0;

• __u32 ext_flags = 0;

while (argc > 0) { if (strcmp(*argv, "dev") == 0) { @@ -492,6 +496,8 @@ static int fdb_modify(int cmd, int flags, int argc, char **argv) req.ndm.ndm_flags |= NTF_EXT_LEARNED; } else if (matches(*argv, "sticky") == 0) { req.ndm.ndm_flags |= NTF_STICKY;

• } else if (matches(*argv, "blackhole") == 0) {
  

• 	ext_flags |= NTF_EXT_BLACKHOLE;
  

The policy seems to be to use strcmp() instead of matches() in new code:

https://lore.kernel.org/netdev/f7251b13-dbf2-f86c-6c2a-2c037b208017@gmail.co...

} else {
	if (strcmp(*argv, "to") == 0)
		NEXT_ARG();

@@ -534,6 +540,11 @@ static int fdb_modify(int cmd, int flags, int argc, char **argv) if (dst_ok) addattr_l(&req.n, sizeof(req), NDA_DST, &dst.data, dst.bytelen);

• if (ext_flags &&

•    addattr_l(&req.n, sizeof(req), NDA_FLAGS_EXT, &ext_flags,
  

•       sizeof(ext_flags)) < 0)
  

addattr32() ?

I will check the kernel patches now. I wouldn't submit a new version to iproute2-next until the kernel patches are accepted.

• return -1;
  

• if (vid >= 0) addattr16(&req.n, sizeof(req), NDA_VLAN, vid); if (nhid > 0)

diff --git a/man/man8/bridge.8 b/man/man8/bridge.8 index f4f1d807..0119a2a9 100644 --- a/man/man8/bridge.8 +++ b/man/man8/bridge.8 @@ -85,6 +85,13 @@ bridge - show / manipulate bridge addresses and devices .B nhid .IR NHID " } " +.ti -8 +.BR "bridge fdb" " { " add " | " del " } " +.I LLADR +.B dev +.IR BRDEV " [ " +.BR self " ] [ " local " ] [ " blackhole " ] "

.ti -8 .BR "bridge fdb" " [ [ " show " ] [ " .B br @@ -701,6 +708,11 @@ controller learnt dynamic entry. Kernel will not age such an entry.

• this entry will not change its port due to learning.

.sp +.B blackhole +- this entry will silently discard all matching packets. The entry must +be added as a local permanent entry. +.sp

.in -8 The next command line parameters apply only when the specified device -- 2.34.1