Re: Local Denial-of-Service attack against Linux (fwd)

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Daniel Giemza wrote:
>
>
> Apparently unix domain sockets are ignoring the /proc/sys/net/core/wmem_max
> parameter, despite the documentation to the contrary. The fix should be
> simple, but I haven't had time to chase it down, and I'm not (usually) a
> Linux kernel developer.

* Linux allows you to send one message, even if that message is longer
than wmem_max.
* linux/net/core/sock.c:sock_alloc_send_skb(), around line 800:

        skb=sock_wmalloc(...);
        if(skb)
                break;
+ if(try_size > 131072)
+ break;

should fix the problem [untested]

I noticed 2 further problems:
* 131072 should be a define (KMALLOC_MAX)
* linux/net/unix/af_unix.c:unix_stream_sendmsg() assumes that the page
size is 4096.

        s/4096-16/PAGESIZE/g

--
	Manfred
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• Next message: Thierry Danis: "Very low cpio tansfer rates with 2.2.12-20"
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