From: Sergei Shtylyov <sergei.shtylyov@cogentembedded•com>
To: Ding Tianhong <dingtianhong@huawei•com>
Cc: "David S. Miller" <davem@davemloft•net>,
Alexey Kuznetsov <kuznet@ms2•inr.ac.ru>,
James Morris <jmorris@namei•org>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6•org>,
Netdev <netdev@vger•kernel.org>,
Patrick McHardy <kaber@trash•net>
Subject: Re: [PATCH 1/2] ipv6: do not disable temp_address when reaching max_address
Date: Tue, 13 Aug 2013 18:31:11 +0400 [thread overview]
Message-ID: <520A432F.4000308@cogentembedded.com> (raw)
In-Reply-To: <5209CEE2.70908@huawei.com>
Hello.
On 08/13/2013 10:14 AM, Ding Tianhong wrote:
> A LAN user can remotely disable temporary address which may lead
> to privacy violatins and information disclosure.
> The reason is that the linux kernel uses the 'ipv6.max_addresses'
> option to specify how many ipv6 addresses and interface may have.
> The 'ipv6.regen_max_retry' (default value 3) option specifies
> how many times the kernel will try to create a new address.
> But the kernel is not distinguish between the event of reaching
> max_addresses for an interface and failing to generate a new address.
> the kernel disable the temporary address after regenerate a new
> address 'regen_max_retry' times.
> According RFC4941 3.3.7:
> ---------------------------------------
> If DAD indicates the address is already in use,
> the node must generate a new randomized interface
> identifier as described in section 3.2 above, and
> repeat the previous steps as appropriate up to
> TEMP_IDGEN_RETRIES times.
> If after TEMP_IDGEN_RETRIES consecutive attempts no
> non-unique address was generated, the node must log
> a system error and must not attempt to generate
> temporary address for that interface.
> ------------------------------------------
> RFC4941 3.3.7 specifies that disabling the temp_address must happen
> upon the address is already in use, not reach the max_address,
> So we have to check the return err and distinguish the correct retry path.
> This fixes CVE-2013-0343
> Signed-off-by: Ding Tianhong <dingtianhong@huawei•com>
> Tested-by: Wang Weidong <wangweidong1@huawei•com>
> Cc: David S. Miller <davem@davemloft•net>
> ---
> net/ipv6/addrconf.c | 25 +++++++++++++++++++++----
> 1 file changed, 21 insertions(+), 4 deletions(-)
> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> index da4241c..99f9fd5 100644
> --- a/net/ipv6/addrconf.c
> +++ b/net/ipv6/addrconf.c
> @@ -1134,10 +1134,27 @@ retry:
[...]
> + if (PTR_ERR(ift) == -EEXIST) {
> + pr_info("%s: retry temporary address regeneration\n", __func__);
> + tmpaddr = &addr;
> + write_lock(&idev->lock);
> + goto retry;
> + } else
> + goto out;
According to CodingStyle, both arms of the *if* statement should have {}
if one has it.
WBR, Sergei
next prev parent reply other threads:[~2013-08-13 14:31 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-13 6:14 [PATCH 1/2] ipv6: do not disable temp_address when reaching max_address Ding Tianhong
2013-08-13 14:31 ` Sergei Shtylyov [this message]
2013-08-14 1:41 ` Ding Tianhong
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