| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <202205032027.B2A9FB4AA@keescook>
Date: Tue, 3 May 2022 20:37:35 -0700
From: Kees Cook <keescook@...omium.org>
To: "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc: Rasmus Villemoes <linux@...musvillemoes.dk>,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Rich Felker <dalias@...ifal.cx>,
Eric Dumazet <edumazet@...gle.com>, netdev@...r.kernel.org,
Alexei Starovoitov <ast@...nel.org>,
alsa-devel@...a-project.org, Al Viro <viro@...iv.linux.org.uk>,
Andrew Gabbasov <andrew_gabbasov@...tor.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Andy Gross <agross@...nel.org>,
Andy Lavr <andy.lavr@...il.com>,
Arend van Spriel <aspriel@...il.com>,
Baowen Zheng <baowen.zheng@...igine.com>,
Bjorn Andersson <bjorn.andersson@...aro.org>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Bradley Grove <linuxdrivers@...otech.com>,
brcm80211-dev-list.pdl@...adcom.com,
Christian Brauner <brauner@...nel.org>,
Christian Göttsche <cgzones@...glemail.com>,
Christian Lamparter <chunkeey@...glemail.com>,
Chris Zankel <chris@...kel.net>,
Cong Wang <cong.wang@...edance.com>,
Daniel Axtens <dja@...ens.net>,
Daniel Vetter <daniel.vetter@...ll.ch>,
Dan Williams <dan.j.williams@...el.com>,
David Gow <davidgow@...gle.com>,
David Howells <dhowells@...hat.com>,
Dennis Dalessandro <dennis.dalessandro@...nelisnetworks.com>,
devicetree@...r.kernel.org, Dexuan Cui <decui@...rosoft.com>,
Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
Eli Cohen <elic@...dia.com>,
Eric Paris <eparis@...isplace.org>,
Eugeniu Rosca <erosca@...adit-jv.com>,
Felipe Balbi <balbi@...nel.org>,
Francis Laniel <laniel_francis@...vacyrequired.com>,
Frank Rowand <frowand.list@...il.com>,
Franky Lin <franky.lin@...adcom.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Gregory Greenman <gregory.greenman@...el.com>,
Guenter Roeck <linux@...ck-us.net>,
Haiyang Zhang <haiyangz@...rosoft.com>,
Hante Meuleman <hante.meuleman@...adcom.com>,
Herbert Xu <herbert@...dor.apana.org.au>,
Hulk Robot <hulkci@...wei.com>,
"James E.J. Bottomley" <jejb@...ux.ibm.com>,
James Morris <jmorris@...ei.org>,
Jarkko Sakkinen <jarkko@...nel.org>,
Jaroslav Kysela <perex@...ex.cz>,
Jason Gunthorpe <jgg@...pe.ca>, Jens Axboe <axboe@...nel.dk>,
Johan Hedberg <johan.hedberg@...il.com>,
Johannes Berg <johannes.berg@...el.com>,
Johannes Berg <johannes@...solutions.net>,
John Keeping <john@...anate.com>,
Juergen Gross <jgross@...e.com>, Kalle Valo <kvalo@...nel.org>,
Keith Packard <keithp@...thp.com>, keyrings@...r.kernel.org,
kunit-dev@...glegroups.com,
Kuniyuki Iwashima <kuniyu@...zon.co.jp>,
"K. Y. Srinivasan" <kys@...rosoft.com>,
Lars-Peter Clausen <lars@...afoo.de>,
Lee Jones <lee.jones@...aro.org>,
Leon Romanovsky <leon@...nel.org>,
Liam Girdwood <lgirdwood@...il.com>,
linux1394-devel@...ts.sourceforge.net,
linux-afs@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org,
linux-arm-msm@...r.kernel.org, linux-bluetooth@...r.kernel.org,
linux-hardening@...r.kernel.org, linux-hyperv@...r.kernel.org,
linux-integrity@...r.kernel.org, linux-rdma@...r.kernel.org,
linux-scsi@...r.kernel.org, linux-security-module@...r.kernel.org,
linux-usb@...r.kernel.org, linux-wireless@...r.kernel.org,
linux-xtensa@...ux-xtensa.org, llvm@...ts.linux.dev,
Loic Poulain <loic.poulain@...aro.org>,
Louis Peens <louis.peens@...igine.com>,
Luca Coelho <luciano.coelho@...el.com>,
Luiz Augusto von Dentz <luiz.dentz@...il.com>,
Marc Dionne <marc.dionne@...istor.com>,
Marcel Holtmann <marcel@...tmann.org>,
Mark Brown <broonie@...nel.org>,
"Martin K. Petersen" <martin.petersen@...cle.com>,
Max Filippov <jcmvbkbc@...il.com>,
Mimi Zohar <zohar@...ux.ibm.com>,
Muchun Song <songmuchun@...edance.com>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Nuno Sá <nuno.sa@...log.com>,
Paolo Abeni <pabeni@...hat.com>,
Paul Moore <paul@...l-moore.com>,
Rob Herring <robh+dt@...nel.org>,
Russell King <linux@...linux.org.uk>, selinux@...r.kernel.org,
"Serge E. Hallyn" <serge@...lyn.com>,
SHA-cyfmac-dev-list@...ineon.com,
Simon Horman <simon.horman@...igine.com>,
Stefano Stabellini <sstabellini@...nel.org>,
Stefan Richter <stefanr@...6.in-berlin.de>,
Steffen Klassert <steffen.klassert@...unet.com>,
Stephen Hemminger <sthemmin@...rosoft.com>,
Stephen Smalley <stephen.smalley.work@...il.com>,
Tadeusz Struk <tadeusz.struk@...aro.org>,
Takashi Iwai <tiwai@...e.com>, Tom Rix <trix@...hat.com>,
Udipto Goswami <quic_ugoswami@...cinc.com>,
Vincenzo Frascino <vincenzo.frascino@....com>,
wcn36xx@...ts.infradead.org, Wei Liu <wei.liu@...nel.org>,
xen-devel@...ts.xenproject.org,
Xiu Jianfeng <xiujianfeng@...wei.com>,
Yang Yingliang <yangyingliang@...wei.com>
Subject: Re: [PATCH 01/32] netlink: Avoid memcpy() across flexible array
boundary
On Tue, May 03, 2022 at 10:31:05PM -0500, Gustavo A. R. Silva wrote:
> On Tue, May 03, 2022 at 06:44:10PM -0700, Kees Cook wrote:
> [...]
> > diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
> > index 1b5a9c2e1c29..09346aee1022 100644
> > --- a/net/netlink/af_netlink.c
> > +++ b/net/netlink/af_netlink.c
> > @@ -2445,7 +2445,10 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
> > NLMSG_ERROR, payload, flags);
> > errmsg = nlmsg_data(rep);
> > errmsg->error = err;
> > - memcpy(&errmsg->msg, nlh, payload > sizeof(*errmsg) ? nlh->nlmsg_len : sizeof(*nlh));
> > + errmsg->msg = *nlh;
> > + if (payload > sizeof(*errmsg))
> > + memcpy(errmsg->msg.nlmsg_payload, nlh->nlmsg_payload,
> > + nlh->nlmsg_len - sizeof(*nlh));
>
> They have nlmsg_len()[1] for the length of the payload without the header:
>
> /**
> * nlmsg_len - length of message payload
> * @nlh: netlink message header
> */
> static inline int nlmsg_len(const struct nlmsghdr *nlh)
> {
> return nlh->nlmsg_len - NLMSG_HDRLEN;
> }
Oh, hm, yeah, that would be much cleaner. The relationship between
"payload" and nlmsg_len is confusing in here. :)
So, this should be simpler:
- memcpy(&errmsg->msg, nlh, payload > sizeof(*errmsg) ? nlh->nlmsg_len : sizeof(*nlh));
+ errmsg->msg = *nlh;
+ memcpy(errmsg->msg.nlmsg_payload, nlh->nlmsg_payload, nlmsg_len(nlh));
It's actually this case that triggered my investigation in __bos(1)'s
misbehavior around sub-structs, since this case wasn't getting silenced:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101832
It still feels like it should be possible to get this right without
splitting the memcpy, though. Hmpf.
> (would that function use some sanitization, though? what if nlmsg_len is
> somehow manipulated to be less than NLMSG_HDRLEN?...)
Maybe something like:
static inline int nlmsg_len(const struct nlmsghdr *nlh)
{
if (WARN_ON(nlh->nlmsg_len < NLMSG_HDRLEN))
return 0;
return nlh->nlmsg_len - NLMSG_HDRLEN;
}
> Also, it seems there is at least one more instance of this same issue:
>
> diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c
> index 16ae92054baa..d06184b94af5 100644
> --- a/net/netfilter/ipset/ip_set_core.c
> +++ b/net/netfilter/ipset/ip_set_core.c
> @@ -1723,7 +1723,8 @@ call_ad(struct net *net, struct sock *ctnl, struct sk_buff *skb,
> nlh->nlmsg_seq, NLMSG_ERROR, payload, 0);
> errmsg = nlmsg_data(rep);
> errmsg->error = ret;
> - memcpy(&errmsg->msg, nlh, nlh->nlmsg_len);
> + errmsg->msg = *nlh;
> + memcpy(errmsg->msg.nlmsg_payload, nlh->nlmsg_payload, nlmsg_len(nlh));
Ah, yes, nice catch!
> cmdattr = (void *)&errmsg->msg + min_len;
>
> ret = nla_parse(cda, IPSET_ATTR_CMD_MAX, cmdattr,
>
> --
> Gustavo
>
> [1] https://elixir.bootlin.com/linux/v5.18-rc5/source/include/net/netlink.h#L577
--
Kees Cook
Powered by blists - more mailing lists