From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id 9288AA00E6 for ; Wed, 10 Jul 2019 22:32:04 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 2F540322C; Wed, 10 Jul 2019 22:32:03 +0200 (CEST) Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by dpdk.org (Postfix) with ESMTP id DDB94231E for ; Wed, 10 Jul 2019 22:32:01 +0200 (CEST) Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 45C7B30ADC7C; Wed, 10 Jul 2019 20:32:01 +0000 (UTC) Received: from dhcp-25.97.bos.redhat.com (unknown [10.18.25.208]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 650641001947; Wed, 10 Jul 2019 20:32:00 +0000 (UTC) From: Aaron Conole To: Stephen Hemminger Cc: dev@dpdk.org, Olivier Matz , Andrew Rybchenko , Ferruh Yigit , Michael Santana References: <20190710183342.6459-1-aconole@redhat.com> <20190710114230.7c171c7a@hermes.lan> <20190710122756.62ec19a9@hermes.lan> Date: Wed, 10 Jul 2019 16:31:59 -0400 In-Reply-To: <20190710122756.62ec19a9@hermes.lan> (Stephen Hemminger's message of "Wed, 10 Jul 2019 12:27:56 -0700") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.47]); Wed, 10 Jul 2019 20:32:01 +0000 (UTC) Subject: Re: [dpdk-dev] [PATCH] rte_ether: force format string for unformat_addr X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Stephen Hemminger writes: > On Wed, 10 Jul 2019 15:13:02 -0400 > Aaron Conole wrote: > >> Stephen Hemminger writes: >> >> > On Wed, 10 Jul 2019 14:33:42 -0400 >> > Aaron Conole wrote: >> > >> >> rte_ether_unformation_addr is very lax in what it accepts now, including >> >> ethernet addresses formatted ambiguously as "x:xx:x:xx:x:xx". However, >> >> previously this behavior was enforced via the my_ether_aton which would >> >> fail ambiguously formatted values. >> >> >> >> Reported-by: Michael Santana >> >> Fixes: 596d31092d32 ("net: add function to convert string to ethernet address") >> >> Signed-off-by: Aaron Conole >> >> --- >> >> lib/librte_net/rte_ether.c | 6 ++++-- >> >> 1 file changed, 4 insertions(+), 2 deletions(-) >> >> >> >> diff --git a/lib/librte_net/rte_ether.c b/lib/librte_net/rte_ether.c >> >> index 8d040173c..4f252b813 100644 >> >> --- a/lib/librte_net/rte_ether.c >> >> +++ b/lib/librte_net/rte_ether.c >> >> @@ -45,7 +45,8 @@ rte_ether_unformat_addr(const char *s, struct rte_ether_addr *ea) >> >> if (n == 6) { >> >> /* Standard format XX:XX:XX:XX:XX:XX */ >> >> if (o0 > UINT8_MAX || o1 > UINT8_MAX || o2 > UINT8_MAX || >> >> - o3 > UINT8_MAX || o4 > UINT8_MAX || o5 > UINT8_MAX) { >> >> + o3 > UINT8_MAX || o4 > UINT8_MAX || o5 > UINT8_MAX || >> >> + strlen(s) != RTE_ETHER_ADDR_FMT_SIZE - 1) { >> >> rte_errno = ERANGE; >> >> return -1; >> >> } >> >> @@ -58,7 +59,8 @@ rte_ether_unformat_addr(const char *s, struct rte_ether_addr *ea) >> >> ea->addr_bytes[5] = o5; >> >> } else if (n == 3) { >> >> /* Support the format XXXX:XXXX:XXXX */ >> >> - if (o0 > UINT16_MAX || o1 > UINT16_MAX || o2 > UINT16_MAX) { >> >> + if (o0 > UINT16_MAX || o1 > UINT16_MAX || o2 > UINT16_MAX || >> >> + strlen(s) != RTE_ETHER_ADDR_FMT_SIZE - 4) { >> >> rte_errno = ERANGE; >> >> return -1; >> >> } >> > >> > NAK >> > Skipping leading zero should be ok. There is no need for this patch. >> >> Is it intended to skip the leading 0? Why not the trailing 0? I'm not >> familiar with the format that is used here (example - X:XX:X:XX:X) >> >> It isn't described in any RFC I could find (but I only did a small >> search). Even in IEEE, the format is always a full octet. >> >> > The current behavior is superset of what standard ether_aton accepts. >> >> Okay, but it introduces a test failure for the cmdline tests and then >> that test will need a few lines removed for 'unsuccessful' formats. >> >> ether_aton is much more rigid in the formats it accepts, so the test >> case is enforcing that. I guess either the current behavior of this >> function changes (and since it is a new behavior of the cmdline parser, >> I would think it should be changed) or the test case should be changed >> to adopt it. > > BSD ether_aton is: > /* > * Convert an ASCII representation of an ethernet address to binary form. > */ > struct ether_addr * > ether_aton_r(const char *a, struct ether_addr *e) > { > int i; > unsigned int o0, o1, o2, o3, o4, o5; > > i = sscanf(a, "%x:%x:%x:%x:%x:%x", &o0, &o1, &o2, &o3, &o4, &o5); > if (i != 6) > return (NULL); > e->octet[0]=o0; > e->octet[1]=o1; > e->octet[2]=o2; > e->octet[3]=o3; > e->octet[4]=o4; > e->octet[5]=o5; > return (e); > } Your implementation fixes the above by bounds checking each octet to enforce that in the 6-octet form, each octet is bound to the region 00-ff. The BSD example only accepts a 6-octet form. Your version is intended to accept both colon forms so x:x:x will successfully parse as well (interpreted on the XXXX:XXXX:XXXX side) (ie: mac 02:03:04 or 2:3:4 would be accepted). Further, accidentally passing an ipv6 address to this routine (something a user of a cmdline interface might do) could be parsed as valid (example: 2001:db8:2::1) - which would be the wrong thing. I think it would be strange for length limits to be enforced in cmdline parser *after* calling this, but that might be an option for fixing (so patch cmdline_parse_etheraddr to do a length check after the unformat_addr call). I guess I'm not sure what the *best* fix would be. I think the most sane fix is what I've put in since it will only allow the commonly accepted notation, and not allow ad-hoc accidents. Higher layers (like cmdline parsers) are free to implement routines that reformat the lax forms (like you might want to allow a user to pass) into more restrictive forms required by a lower layer (like librte_net). I concede that there could be a more friendly thing to do in some specific cases - but then we must more strictly validate the *form* (ie: we have a scanf where one form is a subset of another and will be okay with some kinds of invalid characters being inserted - allowing for things like IPV6 addresses looking like ethernet hardware addresses).