IPV6 raw socket denies bind(2)

IPV6 raw socket denies bind(2)

[Jan Engelhardt]

[Doublepost: linux-netdev does not exist. Sigh. "netdev" is totally 
nonstandard to all the other linux-* list names. :-?]

Hi,


I was trying out raw sockets and stumbled into a case whereby I cannot 
call bind(2) on a AF_INET6, SOCK_RAW socket. Apparently, I am triggering 
this particular code path that means absolutely nothing to me:

# ./rawtest

kernel pseudo callgraph:
static int rawv6_bind(struct sock *sk, struct sockaddr *uaddr, int 
addr_len)
addr >= SIN6_LEN_RFC2133
addr_type != IPV6_ADDR_MAPPED
sk->sk_state == TCP_CLOSED
addr_type != IPV6_ADDR_ANY
!(addr_type & IPV6_ADDR_LINKLOCAL)
!(addr_type & IPV6_ADDR_MULTICAST)
dev == NULL
ipv6_chk_addr does not have any addresses to loop through (wtf? checked 
with printk.)
=> going -EADDRNOTAVAIL

At this point I have no idea why ipv6_chk_addr does not run through 
its loop. No devices in the hash bucket or something. Happens in 
2.6.36. I hope somebody can shed some light here.

---Userspace testcase---
#include <sys/socket.h>
#include <stdio.h>
#include <string.h>
#include <netinet/udp.h>
#include <netinet/in.h>
#include <netinet/ip6.h>
#include <arpa/inet.h>
#include <stdlib.h>

int main(void)
{
	struct sockaddr_in6 src = {};
	int sk;

	sk = socket(AF_INET6, SOCK_RAW, IPPROTO_UDP);
	memset(&src, 0, sizeof(src));
	inet_pton(AF_INET6, "::1", &src);
	src.sin6_family = AF_INET6;

	if (bind(sk, (void *)&src, sizeof(src)) < 0) {
		perror("bind");
		abort();
	}
	return 0;
}

Re: IPV6 raw socket denies bind(2)

[Brian Haley]

On 10/27/2010 06:01 PM, Jan Engelhardt wrote:
> int main(void)
> {
> 	struct sockaddr_in6 src = {};
> 	int sk;
> 
> 	sk = socket(AF_INET6, SOCK_RAW, IPPROTO_UDP);
> 	memset(&src, 0, sizeof(src));
> 	inet_pton(AF_INET6, "::1", &src);
> 	src.sin6_family = AF_INET6;
> 
> 	if (bind(sk, (void *)&src, sizeof(src)) < 0) {
> 		perror("bind");
> 		abort();
> 	}
> 	return 0;
> }

You're trashing the sockaddr, try this patch:

< 	inet_pton(AF_INET6, "::1", &src);
---
> 	inet_pton(AF_INET6, "::1", &src.sin6_addr);

-Brian

Re: IPV6 raw socket denies bind(2)

[Rémi Denis-Courmont]

On Thu, 28 Oct 2010 00:01:57 +0200 (CEST), Jan Engelhardt
<jengelh@medozas.de> wrote:
> #include <sys/socket.h>
> #include <stdio.h>
> #include <string.h>
> #include <netinet/udp.h>
> #include <netinet/in.h>
> #include <netinet/ip6.h>
> #include <arpa/inet.h>
> #include <stdlib.h>
> 
> int main(void)
> {
> 	struct sockaddr_in6 src = {};
> 	int sk;
> 
> 	sk = socket(AF_INET6, SOCK_RAW, IPPROTO_UDP);
> 	memset(&src, 0, sizeof(src));
> 	inet_pton(AF_INET6, "::1", &src);

That should be:
inet_pton(AF_INET6, "::1", &src.sin6_addr);
No wonder it does not work.


-- 
Rémi Denis-Courmont
http://www.remlab.net
http://fi.linkedin.com/in/remidenis