| Message ID | 20180413181618.24144-1-sven@narfation.org (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Commit | 9f22e3d0ed2a3d83479f3db3b570f49218024249 |
| Delegated to: | Simon Wunderlich |
| Headers |
Return-Path: <b.a.t.m.a.n-bounces@lists.open-mesh.org> X-Original-To: patchwork@open-mesh.org Delivered-To: patchwork@open-mesh.org Received: from open-mesh.org (localhost [IPv6:::1]) by open-mesh.org (Postfix) with ESMTP id 1B67D81119; Fri, 13 Apr 2018 20:16:31 +0200 (CEST) Authentication-Results: open-mesh.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=narfation.org header.i=@narfation.org header.b="OE9DL0Mi"; dkim-atps=neutral Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=2001:4d88:2000:7::2; helo=v3-1039.vlinux.de; envelope-from=sven@narfation.org; receiver=<UNKNOWN> Received: from v3-1039.vlinux.de (narfation.org [IPv6:2001:4d88:2000:7::2]) by open-mesh.org (Postfix) with ESMTPS id A291C8023E for <b.a.t.m.a.n@lists.open-mesh.org>; Fri, 13 Apr 2018 20:16:28 +0200 (CEST) Received: from sven-desktop.home.narfation.org (p200300C593C58EF90000000000004065.dip0.t-ipconnect.de [IPv6:2003:c5:93c5:8ef9::4065]) by v3-1039.vlinux.de (Postfix) with ESMTPSA id B7444110116; Fri, 13 Apr 2018 20:16:27 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=narfation.org; s=20121; t=1523643387; bh=xOjCXlcnvCcYvsqfgMCXBnGnbIfHQiM29IO627FD7UQ=; h=From:To:Cc:Subject:Date:From; b=OE9DL0Mi60nxLSyJEMYyqqV0R2hC1diK1GyDS0UfOtTWSPzet2C1KrQqzyckASRpv zpSIu1989tk7cTlAEiXrEe51GZLvcKLUHL0g1AynxTMgM7XMAHQ+eprhvzqPoI+0z0 Hf+M2sGCimxi8HkeiHLYHehERHeu8pzzfnsBWLzo= From: Sven Eckelmann <sven@narfation.org> To: b.a.t.m.a.n@lists.open-mesh.org Date: Fri, 13 Apr 2018 20:16:18 +0200 Message-Id: <20180413181618.24144-1-sven@narfation.org> X-Mailer: git-send-email 2.17.0 Subject: [B.A.T.M.A.N.] [PATCH] batctl: Validate translated mac addresses X-BeenThere: b.a.t.m.a.n@lists.open-mesh.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: The list for a Better Approach To Mobile Ad-hoc Networking <b.a.t.m.a.n.lists.open-mesh.org> List-Unsubscribe: <https://lists.open-mesh.org/mm/options/b.a.t.m.a.n>, <mailto:b.a.t.m.a.n-request@lists.open-mesh.org?subject=unsubscribe> List-Archive: <http://lists.open-mesh.org/pipermail/b.a.t.m.a.n/> List-Post: <mailto:b.a.t.m.a.n@lists.open-mesh.org> List-Help: <mailto:b.a.t.m.a.n-request@lists.open-mesh.org?subject=help> List-Subscribe: <https://lists.open-mesh.org/mm/listinfo/b.a.t.m.a.n>, <mailto:b.a.t.m.a.n-request@lists.open-mesh.org?subject=subscribe> Reply-To: The list for a Better Approach To Mobile Ad-hoc Networking <b.a.t.m.a.n@lists.open-mesh.org> Cc: Andre Kasper <Andre.Kasper@gmx.de> Errors-To: b.a.t.m.a.n-bounces@lists.open-mesh.org Sender: "B.A.T.M.A.N" <b.a.t.m.a.n-bounces@lists.open-mesh.org> |
| Series |
batctl: Validate translated mac addresses
|
|
Commit Message
Sven Eckelmann
April 13, 2018, 6:16 p.m. UTC
The IP translation layer is using the neighbor table of the kernel to get
the unicast link layer (mac) address for IP(v4|v6) addresses. The kernel
can not only return unicast mac addresses to such an RTM_GETNEIGH request
but also zero mac address. Such an address must be considered invalid
because the global translation table may not only contain a unique client
mac address entry for it. The translation from client mac to originator
will therefore most likely return an unexpected originator.
Dropping these kind of (bogus) results avoids confusions while using things
like batctl's ping or traceroute.
Reported-by: Andre Kasper <Andre.Kasper@gmx.de>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
Cc: Andre Kasper <Andre.Kasper@gmx.de>
See https://www.open-mesh.org/issues/353
---
functions.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
Comments
On 14/04/18 02:16, Sven Eckelmann wrote: > The IP translation layer is using the neighbor table of the kernel to get > the unicast link layer (mac) address for IP(v4|v6) addresses. The kernel > can not only return unicast mac addresses to such an RTM_GETNEIGH request > but also zero mac address. Such an address must be considered invalid > because the global translation table may not only contain a unique client > mac address entry for it. The translation from client mac to originator > will therefore most likely return an unexpected originator. > We already handle the case of multiple originators handling the same MAC address, no? In that case I think we pick the "best" originator. This case sounds more like a validity check because "a zero MAC should not be in the translation table", or am I wrong? Cheers,
On Samstag, 14. April 2018 04:34:42 CEST Antonio Quartulli wrote: > > On 14/04/18 02:16, Sven Eckelmann wrote: [...] > We already handle the case of multiple originators handling the same MAC > address, no? In that case I think we pick the "best" originator. Yes, but this doesn't make a lot of sense for multicast and zero mac addresses. The translate layer of batctl is usually used to ping/traceroute to some originator. But multicast and zero mac addresses don't represent a "client" which can be used to identify some originator. So it doesn't seem to make sense to allow them here. Or even without the ping/traceroute stuff, the concept of calling `batctl translate` should give you an answer which you can understand. So it should tell you that batman-adv is very likely to transmit a unicast packet with this destination address to this originator. But this cannot work for multicast destination addresses because multiple answer should be given here - which is out of scope for this command. Which reminds me that I should propose a second patch which checks whether the input for translate_mac is "valid" before trying to translate it. > This case sounds more like a validity check because "a zero MAC should > not be in the translation table", or am I wrong? Partially, yes. I personally don't care (at the moment) whether there is a zero mac address in the translation table. The current translation table code (batadv_tt_local_add) doesn't check whether there is a zero mac address (is_zero_ether_addr). But Linus had some ideas when zero mac addresses can be useful - maybe he tell us whether it makes sense/problems to have them in the translation table. Kind regards, Sven
On 14/04/18 15:10, Sven Eckelmann wrote: > On Samstag, 14. April 2018 04:34:42 CEST Antonio Quartulli wrote: >> >> On 14/04/18 02:16, Sven Eckelmann wrote: > [...] >> We already handle the case of multiple originators handling the same MAC >> address, no? In that case I think we pick the "best" originator. > > Yes, but this doesn't make a lot of sense for multicast and zero mac > addresses. The translate layer of batctl is usually used to ping/traceroute to > some originator. But multicast and zero mac addresses don't represent a > "client" which can be used to identify some originator. So it doesn't seem to > make sense to allow them here. Right. > > Or even without the ping/traceroute stuff, the concept of calling `batctl > translate` should give you an answer which you can understand. So it should > tell you that batman-adv is very likely to transmit a unicast packet with this > destination address to this originator. But this cannot work for multicast > destination addresses because multiple answer should be given here - which is > out of scope for this command. Which reminds me that I should propose a second > patch which checks whether the input for translate_mac is "valid" before > trying to translate it. > >> This case sounds more like a validity check because "a zero MAC should >> not be in the translation table", or am I wrong? > > Partially, yes. I personally don't care (at the moment) whether there is a > zero mac address in the translation table. The current translation table code > (batadv_tt_local_add) doesn't check whether there is a zero mac address > (is_zero_ether_addr). But Linus had some ideas when zero mac addresses can be > useful - maybe he tell us whether it makes sense/problems to have them in the > translation table. Yeah, I agree that zero "may appear" in the table and therefore we have to "check" what we are getting back and whether it makes sense for us in this context. Actually my comment was not about changing your approach, but just making it more explicit in the commit and in the error message. An error message like like "returned invalid all-zero mac address" (or "multicast address") might help to distinguish similar "ambiguities" in the future. No? Cheers, > > Kind regards, > Sven >
On Samstag, 14. April 2018 10:11:28 CEST Antonio Quartulli wrote: > An error message like like "returned invalid all-zero mac address" (or > "multicast address") might help to distinguish similar "ambiguities" in > the future. No? The current interface for the translation is "give me a string and I return NULL or a mac address". The resolving of the IPs for hostnames and the check of the neighbor table are done on an "I take what I get first" approach. Your suggestion would involve a change of this interface and parsing of additional information and tracking of states to make sure that the "best" result is returned (or a special error state). This is nothing which I will implement now. Should I drop the patch for now? Kind regards, Sven
On 14/04/18 17:20, Sven Eckelmann wrote: > On Samstag, 14. April 2018 10:11:28 CEST Antonio Quartulli wrote: >> An error message like like "returned invalid all-zero mac address" (or >> "multicast address") might help to distinguish similar "ambiguities" in >> the future. No? > > The current interface for the translation is "give me a string and I return > NULL or a mac address". The resolving of the IPs for hostnames and the check > of the neighbor table are done on an "I take what I get first" approach. Your > suggestion would involve a change of this interface and parsing of additional > information and tracking of states to make sure that the "best" result is > returned (or a special error state). This is nothing which I will implement > now. Oh ok, I went through the code and now I better understand what you meant. > > Should I drop the patch for now? > I'd suggest to still consider it for merging. Even if we can't be specific about the error, it is still better to stop the translation rather than generating unexpected results. Cheers,
On 14/04/18 02:16, Sven Eckelmann wrote: > The IP translation layer is using the neighbor table of the kernel to get > the unicast link layer (mac) address for IP(v4|v6) addresses. The kernel > can not only return unicast mac addresses to such an RTM_GETNEIGH request > but also zero mac address. Such an address must be considered invalid > because the global translation table may not only contain a unique client > mac address entry for it. The translation from client mac to originator > will therefore most likely return an unexpected originator. > > Dropping these kind of (bogus) results avoids confusions while using things > like batctl's ping or traceroute. > > Reported-by: Andre Kasper <Andre.Kasper@gmx.de> > Signed-off-by: Sven Eckelmann <sven@narfation.org> Acked-by: Antonio Quartulli <a@unstable.cc>
On Freitag, 13. April 2018 20:16:18 CEST Sven Eckelmann wrote: > The IP translation layer is using the neighbor table of the kernel to get > the unicast link layer (mac) address for IP(v4|v6) addresses. The kernel > can not only return unicast mac addresses to such an RTM_GETNEIGH request > but also zero mac address. Such an address must be considered invalid > because the global translation table may not only contain a unique client > mac address entry for it. The translation from client mac to originator > will therefore most likely return an unexpected originator. > > Dropping these kind of (bogus) results avoids confusions while using things > like batctl's ping or traceroute. > > Reported-by: Andre Kasper <Andre.Kasper@gmx.de> > Signed-off-by: Sven Eckelmann <sven@narfation.org> > --- > Cc: Andre Kasper <Andre.Kasper@gmx.de> > > See https://www.open-mesh.org/issues/353 Applied in 9f22e3d0ed2a [1]. But the ticket is not marked as resolved but it seems like the reporter wants a different behavior. Kind regards, Sven [1] https://git.open-mesh.org/batctl.git/commit/9f22e3d0ed2a3d83479f3db3b570f49218024249
diff --git a/functions.c b/functions.c index cd92b60..3c340a2 100644 --- a/functions.c +++ b/functions.c @@ -571,6 +571,19 @@ static struct nla_policy neigh_policy[NDA_MAX+1] = { [NDA_PROBES] = { .type = NLA_U32 }, }; +static bool ether_addr_valid(const uint8_t *addr) +{ + /* no multicast address */ + if (addr[0] & 0x01) + return false; + + /* no zero address */ + if ((addr[0] | addr[1] | addr[2] | addr[3] | addr[4] | addr[5]) == 0) + return false; + + return true; +} + static int resolve_mac_from_parse(struct nl_msg *msg, void *arg) { struct nlattr *tb[NDA_MAX + 1]; @@ -616,6 +629,9 @@ static int resolve_mac_from_parse(struct nl_msg *msg, void *arg) mac = nla_data(tb[NDA_LLADDR]); l3addr = nla_data(tb[NDA_DST]); + if (!ether_addr_valid(mac)) + goto err; + if (memcmp(nl_arg->l3addr, l3addr, l3_len) == 0) { memcpy(nl_arg->mac_result, mac, ETH_ALEN); nl_arg->found = 1;