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From: Paul Moore <paul@paul-moore.com>
To: Nazarov Sergey <s-nazarov@yandex.ru>
Cc: "linux-security-module@vger.kernel.org" 
	<linux-security-module@vger.kernel.org>,
	"selinux@vger.kernel.org" <selinux@vger.kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Casey Schaufler <casey@schaufler-ca.com>
Subject: Re: Kernel memory corruption in CIPSO labeled TCP packets processing.
Date: Wed, 30 Jan 2019 21:10:16 -0500	[thread overview]
Message-ID: <CAHC9VhQcrnXmjcVw_ppwM-fGcwhJq9SafTnZKjgpQpxK0ie+Jw@mail.gmail.com> (raw)
In-Reply-To: <3191601548853902@myt6-23299ba78d64.qloud-c.yandex.net>

On Wed, Jan 30, 2019 at 8:11 AM Nazarov Sergey <s-nazarov@yandex.ru> wrote:
> 30.01.2019, 01:42, "Paul Moore" <paul@paul-moore.com>:
> > There are several cases where the stack ends up calling icmp_send()
> > after the skb has been through ip_options_compile(), that should be
> > okay.
> >
> > --
> > paul moore
> > www.paul-moore.com
>
> In those cases precompiled ip_options struct used, without the need to reuse ip_options_compile.
> I think, for error ICMP packet, we can discard all other options except CIPSO. It will be better, than
> send packet, contains wrong option's data. Modified patch 2:
> ---
>  net/ipv4/cipso_ipv4.c |   24 ++++++++++++++++++++++--
>  1 files changed, 22 insertions(+), 2 deletions(-)

This isn't how the rest of the stack works, look at
ip_local_deliver_finish() for one example.  Perhaps the behavior you
are proposing is correct, but please show me where in the various RFC
specs it is defined so that I can better understand why it should work
this way.

> diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
> index 777fa3b..797826c 100644
> --- a/net/ipv4/cipso_ipv4.c
> +++ b/net/ipv4/cipso_ipv4.c
> @@ -1735,13 +1735,33 @@ int cipso_v4_validate(const struct sk_buff *skb, unsigned char **option)
>   */
>  void cipso_v4_error(struct sk_buff *skb, int error, u32 gateway)
>  {
> +       struct ip_options opt;
> +       unsigned char *optptr;
> +
>         if (ip_hdr(skb)->protocol == IPPROTO_ICMP || error != -EACCES)
>                 return;
>
> +       /*
> +        * We might be called above the IP layer,
> +        * so we can not use icmp_send and IPCB here.
> +        *
> +        * For the generated ICMP packet, we create a
> +        * temporary ip _options structure, contains
> +        * the CIPSO option only, since the other options data
> +        * could be modified when the original packet receiving.
> +        */
> +
> +       memset(&opt, 0, sizeof(struct ip_options));
> +       optptr = cipso_v4_optptr(skb);
> +       if (optptr) {
> +               opt.optlen = optptr[1];
> +               opt.cipso = optptr - skb_network_header(skb);
> +       }
> +
>         if (gateway)
> -               icmp_send(skb, ICMP_DEST_UNREACH, ICMP_NET_ANO, 0);
> +               __icmp_send(skb, ICMP_DEST_UNREACH, ICMP_NET_ANO, 0, &opt);
>         else
> -               icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_ANO, 0);
> +               __icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_ANO, 0, &opt);
>  }
>
>  /**
>


-- 
paul moore
www.paul-moore.com

  reply	other threads:[~2019-01-31  2:10 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-15 17:06 Kernel memory corruption in CIPSO labeled TCP packets processing Nazarov Sergey
2019-01-15 17:55 ` Casey Schaufler
2019-01-15 19:52   ` Paul Moore
2019-01-18 14:53     ` Paul Moore
2019-01-18 16:34       ` Nazarov Sergey
2019-01-18 17:17         ` Paul Moore
2019-01-21 17:11           ` Nazarov Sergey
2019-01-22 16:49             ` Paul Moore
2019-01-22 17:35               ` Nazarov Sergey
2019-01-22 17:48                 ` Paul Moore
2019-01-24 14:46                   ` Nazarov Sergey
2019-01-25 16:45                     ` Paul Moore
2019-01-28 13:10                       ` Nazarov Sergey
2019-01-28 22:18                         ` Paul Moore
2019-01-29  7:23                           ` Nazarov Sergey
2019-01-29 22:42                             ` Paul Moore
2019-01-30 13:11                               ` Nazarov Sergey
2019-01-31  2:10                                 ` Paul Moore [this message]
2019-01-31 13:20                                   ` Nazarov Sergey
2019-02-11 20:37                                     ` Paul Moore
2019-02-11 21:21                                       ` Nazarov Sergey
2019-02-11 23:43                                         ` Paul Moore
2019-02-12 15:10                                           ` [PATCH] NETWORKING: avoid use IPCB in cipso_v4_error Nazarov Sergey
2019-02-13 21:41                                             ` Paul Moore
2019-02-14 18:00                                               ` Nazarov Sergey
2019-02-14 18:59                                                 ` Stephen Smalley
2019-02-14 16:43                                             ` David Miller
2019-02-14 18:14                                               ` Nazarov Sergey
2019-02-15 19:02                                               ` Paul Moore
2019-02-15 20:00                                                 ` David Miller
2019-02-15 20:04                                                   ` Paul Moore
2019-02-18 13:39                                                     ` Nazarov Sergey
2019-02-19  1:25                                                       ` David Miller
2019-02-22 16:35                                                         ` Nazarov Sergey
2019-02-22 17:39                                                           ` [PATCH v2 0/2] " Nazarov Sergey
2019-02-25  1:33                                                             ` David Miller
2019-02-25 16:24                                                               ` [PATCH v2 1/2] " Nazarov Sergey
2019-02-25 22:07                                                                 ` Paul Moore
2019-02-25 22:33                                                                 ` David Miller
2019-02-25 23:30                                                                   ` Paul Moore
2019-02-25 16:27                                                               ` [PATCH v2 2/2] " Nazarov Sergey
2019-02-25 22:06                                                                 ` Paul Moore
2019-02-25 22:34                                                                 ` David Miller
2019-02-22 17:43                                                           ` [PATCH v2 1/2] " Nazarov Sergey
2019-02-22 17:50                                                           ` [PATCH v2 2/2] " Nazarov Sergey
2019-02-25  1:33                                                           ` [PATCH] " David Miller

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