NetBSD Problem Report #56836
From www@netbsd.org Sat May 14 18:50:51 2022
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for <gnats-bugs@gnats.NetBSD.org>; Sat, 14 May 2022 18:50:51 +0000 (UTC)
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Date: Sat, 14 May 2022 18:50:48 +0000 (UTC)
From: andrew.cagney@gmail.com
Reply-To: andrew.cagney@gmail.com
To: gnats-bugs@NetBSD.org
Subject: IPv6 ESN tunneling IPcomp has corrupt header
X-Send-Pr-Version: www-1.0
>Number: 56836
>Category: kern
>Synopsis: IPv6 ESN tunneling IPcomp has corrupt header
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: kern-bug-people
>State: open
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Sat May 14 18:55:00 +0000 2022
>Last-Modified: Thu Oct 20 15:30:02 +0000 2022
>Originator: Andrew Cagney
>Release: 9.2
>Organization:
>Environment:
9.2
>Description:
Below are two packets received by a linux host where the peers are configured to IPsec packets with IPv6 IPcomp + ESP + IPv6
- the first was sent by netbsd; linux rejects it
12:22:02.360081 IP6 (hlim 64, next-header ESP (50) payload length: 60)
2001:db8:1:2::45 > 2001:db8:1:2::23: ESP(spi=0x14df9f91,seq=0x6),
length 60
0x0000: 1200 0064 6423 1200 0064 6445 86dd 6000 ...dd#...ddE..`.
0x0010: 0000 003c 3240 2001 0db8 0001 0002 0000 ...<2@..........
0x0020: 0000 0000 0045 2001 0db8 0001 0002 0000 .....E..........
0x0030: 0000 0000 0023 14df 9f91 0000 0006 2900 .....#........).
0x0040: 0002 4b60 0002 072b 0705 46de 1d40 1623 ..K`...+..F..@.#
0x0050: 0318 3085 40f9 4c30 7e03 834c 33d3 5306 ..0.@.L0~..L3.S.
0x0060: b201 0001 016c 5c17 5eca c317 ec65 8e94 45e0
- the second was sent by linux, it was accepted:
14:00:41.418470 IP6 (flowlabel 0x6a92b, hlim 64, next-header ESP (50)
payload length: 112) 2001:db8:1:2::45 > 2001:db8:1:2::23:
ESP(spi=0xc9a65a98,seq=0x1d), length 112
0x0000: 1200 0064 6423 1200 0064 6445 86dd 6006 ...dd#...ddE..`.
0x0010: a92b 0070 3240 2001 0db8 0001 0002 0000 .+.p2@..........
0x0020: 0000 0000 0045 2001 0db8 0001 0002 0000 .....E..........
0x0030: 0000 0000 0023 c9a6 5a98 0000 001d 2900 .....#..Z.....).
0x0040: 96c4 4b60 5ba9 cde0 60e5 a0c0 c8bb 8381 ..K`[...`.......
0x0050: 8181 9101 0c98 42a0 7c26 18bf 8161 df86 ......B.|&...a..
0x0060: c0c9 0c8c 1eef ea93 4022 b5ff b9c0 3202 ........@"....2.
0x0070: 8242 c222 a262 e212 9252 d232 b272 f20a .B.".b...R.2.r..
0x0080: 8a4a ca2a aa6a ea1a 9a5a da3a ba7a fa06 .J.*.j...Z.:.z..
0x0090: 8646 c626 a666 e600 006c b9fc 757a 76f2 .F.&.f...l..uzv.
0x00a0: 51bf 45d8 50ce Q.E.P.
note what follows what I'm pretty sure is SPI+SEQ in the two packets.
From NetBSD we have:
> 14df 9f91 0000 0006 (SPI+SEQ) 2900 0002
but it should be:
> 2900 a970 (i.e., next-header|flags|cpi where the CPI is below:
> 2001:db8:1:2::45 2001:db8:1:2::23
> ipcomp mode=any spi=43376(0x0000a970) reqid=16390(0x00004006)
Where as from linux we have:
> c9a6 5a98 0000 001d (SPI+SEQ) 2900 96c4
with its CPI:
src 2001:db8:1:2::45 dst 2001:db8:1:2::23
proto comp spi 0x000096c4 reqid 1 mode tunnel
>How-To-Repeat:
For reference, these are the parameters from NetBSD, hopefully the problem isn't there:
2001:db8:1:2::45 2001:db8:1:2::23
ipcomp mode=any spi=43376(0x0000a970) reqid=16390(0x00004006)
C: deflate seq=0x00000000 replay=0 flags=0x00000000 state=mature
created: May 14 15:50:22 2022 current: May 14 16:34:23 2022
diff: 2641(s) hard: 28800(s) soft: 28800(s)
last: May 14 16:31:23 2022 hard: 0(s) soft: 0(s)
current: 539(bytes) hard: 0(bytes) soft: 0(bytes)
allocated: 7 hard: 0 soft: 0
sadb_seq=1 pid=1046 refcnt=0
2001:db8:1:2::45 2001:db8:1:2::23
esp mode=any spi=350199697(0x14df9f91) reqid=16389(0x00004005)
E: null
A: hmac-sha1 7f4bcd34 550b9122 c3b2592f c3e6dd2a a78aed66
seq=0x00000007 replay=64 flags=0x00000000 state=mature
created: May 14 15:50:22 2022 current: May 14 16:34:23 2022
diff: 2641(s) hard: 28800(s) soft: 28800(s)
last: May 14 16:31:23 2022 hard: 0(s) soft: 0(s)
current: 700(bytes) hard: 0(bytes) soft: 0(bytes)
allocated: 7 hard: 0 soft: 0
sadb_seq=0 pid=1046 refcnt=0
2001:db8:0:1::/64[any] 2001:db8:0:2::/64[any] 255(reserved)
out ipsec
ipcomp/tunnel/2001:db8:1:2::45-2001:db8:1:2::23/require
esp/transport//require
spid=2 seq=0 pid=1053
refcnt=0
>Fix:
Don't combine IPcomp+ESP with IPv6, doing that is crazy.
>Audit-Trail:
From: Andrew Cagney <andrew.cagney@gmail.com>
To: gnats-bugs@netbsd.org
Cc:
Subject: Re: kern/56836: IPv6 ESN tunneling IPcomp has corrupt header
Date: Sat, 14 May 2022 21:34:35 -0400
(yes ESP, not ESN)
I suspect something to do with code testing for SADB_X_EXT_RAWCPI,
note this contradiction:
in key.c RAWCPI==0 means use ->spi:
case IPPROTO_IPCOMP:
if ((sav->flags & SADB_X_EXT_RAWCPI) == 0
&& ntohl(sav->spi) >= 0x10000) {
IPSECLOG(LOG_DEBUG, "invalid cpi for IPComp.\n");
return(EINVAL);
}
but in xform_ipcomp.c RAWCPI != 0 means use ->spi vis:
if ((sav->flags & SADB_X_EXT_RAWCPI) == 0)
cpi = sav->alg_enc;
else
cpi = ntohl(sav->spi) & 0xffff;
setting the flag seems to fix packets from NetBSD->linux, but not the reverse.
From: Andrew Cagney <andrew.cagney@gmail.com>
To: kern-bug-people@netbsd.org, gnats-admin@netbsd.org, netbsd-bugs@netbsd.org,
gnats-bugs@netbsd.org
Cc:
Subject: Re: kern/56836: IPv6 ESN tunneling IPcomp has corrupt header
Date: Sun, 15 May 2022 09:41:46 -0400
Looks like a regression introduced by: Add ipv6 support for fast_ipsec
- IPv4 also suffers the problem; it's just that my packet test packet
wasn't big enough to be compressed (IPv6 lacks that)
- the return packet gets dropped by NetBSD ....
From: Andrew Cagney <andrew.cagney@gmail.com>
To: kern-bug-people@netbsd.org, gnats-admin@netbsd.org, netbsd-bugs@netbsd.org,
gnats-bugs@netbsd.org
Cc:
Subject: Re: kern/56836: IPv6 ESN tunneling IPcomp has corrupt header
Date: Mon, 16 May 2022 14:13:57 -0400
(so how do I bundle patches)
always always send / expect CPI in IPcomp header
Fixes kern/56836 where an IPsec interop combining compression and
ESP|AH would fail.
Since fast ipsec, the outgoing IPcomp header has contained the
compression algorithm instead of the CPI. Adding the
SADB_X_EXT_RAWCPI flag worked around this but ...
The IPcomp's SADB was unconditionally hashed using the compression
algorithm instead of the CPI. This meant that an incoming packet with
a valid CPI could never match its SADB.
---
sys/netipsec/key.c | 5 +----
sys/netipsec/xform_ipcomp.c | 7 +------
2 files changed, 2 insertions(+), 10 deletions(-)
diff --git a/sys/netipsec/key.c b/sys/netipsec/key.c
index 4ad4a8d466d9..11577960f93f 100644
--- a/sys/netipsec/key.c
+++ b/sys/netipsec/key.c
@@ -8755,10 +8755,7 @@ key_savlut_writer_insert_head(struct secasvar *sav)
KASSERT(mutex_owned(&key_sad.lock));
KASSERT(!sav->savlut_added);
- if (sav->sah->saidx.proto == IPPROTO_IPCOMP)
- hash_key = sav->alg_comp;
- else
- hash_key = sav->spi;
+ hash_key = sav->spi;
hash = key_savluthash(&sav->sah->saidx.dst.sa,
sav->sah->saidx.proto, hash_key, key_sad.savlutmask);
diff --git a/sys/netipsec/xform_ipcomp.c b/sys/netipsec/xform_ipcomp.c
index e94a0b471042..69d196bc7e39 100644
--- a/sys/netipsec/xform_ipcomp.c
+++ b/sys/netipsec/xform_ipcomp.c
@@ -527,7 +527,6 @@ ipcomp_output_cb(struct cryptop *crp)
struct mbuf *m, *mo;
int error, skip, rlen, roff, flags;
uint8_t prot;
- uint16_t cpi;
struct ipcomp * ipcomp;
IPSEC_DECLARE_LOCK_VARIABLE;
@@ -589,11 +588,7 @@ ipcomp_output_cb(struct cryptop *crp)
#endif
}
ipcomp->comp_flags = 0;
-
- if ((sav->flags & SADB_X_EXT_RAWCPI) == 0)
- cpi = sav->alg_enc;
- else
- cpi = ntohl(sav->spi) & 0xffff;
+ uint16_t cpi = ntohl(sav->spi) & 0xffff;
ipcomp->comp_cpi = htons(cpi);
/* Fix Next Protocol in IPv4/IPv6 header */
--
2.35.3
From: Andrew Cagney <andrew.cagney@gmail.com>
To: kern-bug-people@netbsd.org, gnats-admin@netbsd.org, netbsd-bugs@netbsd.org,
gnats-bugs@netbsd.org
Cc:
Subject: Re: kern/56836: IPv6 ESN tunneling IPcomp has corrupt header
Date: Tue, 24 May 2022 14:49:14 -0400
One more thing worth noting. I'm pretty sure that without this
change, racoon can't interop with itself:
racoon/pfkey.c hard-wires SADB_X_EXT_RAWCPI which means:
- outgoing packets do have a correct IPcomp header (i.e., containing
the CPI), but
- incoming packets with that correct CPI never match the SA because
the SA was hashed using the compression algorithm
From: "Christos Zoulas" <christos@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc:
Subject: PR/56836 CVS commit: src/sys/netipsec
Date: Wed, 19 Oct 2022 17:28:03 -0400
Module Name: src
Committed By: christos
Date: Wed Oct 19 21:28:03 UTC 2022
Modified Files:
src/sys/netipsec: key.c xform_ipcomp.c
Log Message:
PR/56836: Andrew Cagney: IPv6 ESN tunneling IPcomp has corrupt header
Always always send / expect CPI in IPcomp header
Fixes kern/56836 where an IPsec interop combining compression and
ESP|AH would fail.
Since fast ipsec, the outgoing IPcomp header has contained the
compression algorithm instead of the CPI. Adding the
SADB_X_EXT_RAWCPI flag worked around this but ...
The IPcomp's SADB was unconditionally hashed using the compression
algorithm instead of the CPI. This meant that an incoming packet with
a valid CPI could never match its SADB.
To generate a diff of this commit:
cvs rdiff -u -r1.277 -r1.278 src/sys/netipsec/key.c
cvs rdiff -u -r1.74 -r1.75 src/sys/netipsec/xform_ipcomp.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
From: Andrew Cagney <andrew.cagney@gmail.com>
To: gnats-bugs@netbsd.org
Cc: kern-bug-people@netbsd.org, gnats-admin@netbsd.org, netbsd-bugs@netbsd.org
Subject: Re: PR/56836 CVS commit: src/sys/netipsec
Date: Thu, 20 Oct 2022 09:57:57 -0400
Thanks! I can kill our custom build. I'll give it a few days and
then pick up a 9.99 snapshot and test using that.
From: Christos Zoulas <christos@zoulas.com>
To: Andrew Cagney <andrew.cagney@gmail.com>
Cc: gnats-bugs@netbsd.org, kern-bug-people@netbsd.org,
gnats-admin@netbsd.org, netbsd-bugs@netbsd.org
Subject: Re: PR/56836 CVS commit: src/sys/netipsec
Date: Thu, 20 Oct 2022 11:28:05 -0400
Thanks for the reminder! I had it in my flagged mail, but have been really b=
usy!
christos
> On Oct 20, 2022, at 9:58 AM, Andrew Cagney <andrew.cagney@gmail.com> wrote=
:
>=20
> =EF=BB=BFThanks! I can kill our custom build. I'll give it a few days an=
d
> then pick up a 9.99 snapshot and test using that.
(Contact us)
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