[PATCH] IPv6: optionaly validate RAs on raw sockets
ICMPv6 Router Advertisements may now contain informations that is
mostly of interest to userland. This currently mostly consists of
recursive DNS server addresses (though one should expect other
stuff to come).
This patch adds a setsockopt to ICMPv6 sockets to only deliver Router
Advertisements if they pass the same set of checks as the kernel
IPv6 autoconfiguration does, so that userland can parse attributes it
is interested safely (otherwise, it would get and parse advertisements
that the kernel rejected).
N.B.: not too sure about the option name though...
Signed-off-by: Remi Denis-Courmont <[EMAIL PROTECTED]>
diff --git a/include/linux/icmpv6.h b/include/linux/icmpv6.h
index 7c5e981..8c96822 100644
--- a/include/linux/icmpv6.h
+++ b/include/linux/icmpv6.h
@@ -139,6 +139,7 @@ static inline struct icmp6hdr *icmp6_hdr(const struct
sk_buff *skb)
*/
#define ICMPV6_FILTER 1
+#define ICMPV6_VALID_ADVERT2
/*
* ICMPV6 filter
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 648bd1f..af72f02 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -343,7 +343,9 @@ struct ipv6_pinfo {
struct raw6_sock {
/* inet_sock has to be the first member of raw6_sock */
struct inet_sockinet;
- __u32 checksum; /* perform checksum */
+ __u16 unused;
+ __u8valid_advert; /* deliver valid RAs only */
+ __u8checksum; /* perform checksum */
__u32 offset; /* checksum offset */
struct icmp6_filter filter;
/* ipv6_pinfo has to be the last member of raw6_sock, see
inet6_sk_generic */
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index a58459a..da6cb50 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -127,12 +127,35 @@ static __inline__ int icmpv6_filter(struct sock *sk,
struct sk_buff *skb)
if (pskb_may_pull(skb, sizeof(struct icmp6hdr))) {
__u32 *data = &rp->filter.data[0];
- int bit_nr;
+ int type;
icmph = (struct icmp6hdr *) skb->data;
- bit_nr = icmph->icmp6_type;
+ type = icmph->icmp6_type;
- return (data[bit_nr >> 5] & (1 << (bit_nr & 31))) != 0;
+ if (data[type >> 5] & (1 << (type & 31)))
+ return 1;
+
+ /* Userland only wants valid router advertisements? */
+ if (type == NDISC_ROUTER_ADVERTISEMENT &&
+ rp->valid_advert) {
+ struct inet6_dev *idev;
+
+ if (!pskb_may_pull(skb, sizeof(struct ra_msg)) ||
+ !(ipv6_addr_type(&ipv6_hdr(skb)->saddr) &
+ IPV6_ADDR_LINKLOCAL))
+ return 1;
+
+ idev = in6_dev_get(skb->dev);
+ if (!idev)
+ return 1;
+
+ /* Ignore RA when routing */
+ if (idev->cnf.forwarding || !idev->cnf.accept_ra) {
+ in6_dev_put(idev);
+ return 1;
+ }
+ in6_dev_put(idev);
+ }
}
return 0;
}
@@ -877,13 +900,26 @@ do_confirm:
static int rawv6_seticmpfilter(struct sock *sk, int level, int optname,
char __user *optval, int optlen)
{
+ struct raw6_sock *rp = raw6_sk(sk);
+
switch (optname) {
case ICMPV6_FILTER:
if (optlen > sizeof(struct icmp6_filter))
optlen = sizeof(struct icmp6_filter);
- if (copy_from_user(&raw6_sk(sk)->filter, optval, optlen))
+ if (copy_from_user(&rp->filter, optval, optlen))
return -EFAULT;
return 0;
+ case ICMPV6_VALID_ADVERT: {
+ int val;
+
+ if (optlen != sizeof(int))
+ return -EINVAL;
+ if (copy_from_user(&val, optval, sizeof(int)))
+ return -EFAULT;
+ /* -1 resets to default, which is actually 0 */
+ rp->valid_advert = (val > 0);
+ return 0;
+ }
default:
return -ENOPROTOOPT;
}
@@ -894,25 +930,38 @@ static int rawv6_seticmpfilter(struct sock *sk, int
level, int optname,
static int rawv6_geticmpfilter(struct sock *sk, int level, int optname,
char __user *optval, int __user *optlen)
{
+ struct raw6_sock *rp = raw6_sk(sk);
int len;
+ if (get_user(len, optlen))
+ return -EFAULT;
+ if (len < 0)
+ return -EINVAL;
+
switch (optname) {
case ICMPV6_FILTER:
- if (get_user(len, optlen))
- return -EFAULT;
-
Re: [PATCH] IPv6: optionaly validate RAs on raw sockets
In article <[EMAIL PROTECTED]> (at Tue, 10 Jul 2007 21:11:17 +0300), Remi Denis-Courmont <[EMAIL PROTECTED]> says: > ICMPv6 Router Advertisements may now contain informations that is > mostly of interest to userland. This currently mostly consists of > recursive DNS server addresses (though one should expect other > stuff to come). I really do not want to have such non-standard API in kernel. --yoshfuji - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] IPv6: optionaly validate RAs on raw sockets
On Wednesday 11 July 2007 15:29:16 YOSHIFUJI Hideaki / 吉藤英明 wrote: > In article <[EMAIL PROTECTED]> (at Tue, 10 Jul 2007 21:11:17 +0300), Remi Denis-Courmont <[EMAIL PROTECTED]> says: > > ICMPv6 Router Advertisements may now contain informations that is > > mostly of interest to userland. This currently mostly consists of > > recursive DNS server addresses (though one should expect other > > stuff to come). > > I really do not want to have such non-standard API in kernel. I can only think of a very limited set of ways to extract options from RAs that the kernel currently ignores: 1) parse everything in kernel addrconf.c 2) validate RA in kernel, parse userland options in userland 3) parse everything in userland 4) do not support any option of interest to userland ever 5) userland and kernel do their own cooking separately netdev folks already rejected (1) earlier. You just rejected (2) this instant. (3) implies removing addrconf from the kernel completely, which does not sound good, besides being a big waste. (4) means Linux is unusable on IPv6 networks. And it's already been pointed out (5) was not safe/secure (userland may end up accepting something when it should not). I might be missing something because I am a notoriously arrogant moron but it looks like Linux IPv6 is in a dead-end for the time being :-( What do you propose then? -- Rémi Denis-Courmont - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] IPv6: optionaly validate RAs on raw sockets
I think #2 in your list is the right choice, and that has nothing to do with adding a non-standard option (which I completely agree is a bad idea). It looked like you're just checking if the machine is acting as a router or not and if it comes from a link-local address; is that right? Of course, lots of apps already check for "am I a router" and they don't require a new socket option. (!) See everything in the quagga package, for example. And checking the address type in a app is trivial. The previous discussion about "validation" was talking about RA's that are forged, so don't pass IPsec authentication checks. I don't see any reason at all to deliver those to an application (ever), so no non-standard socket option required there. I don't know if those are currently delivered on raw sockets or not, but if they are, I think it's reasonable to have a patch that clones them only after authentication rather than before. Prior discussion used FUD about some monitoring apps needing to see forged RA's. I don't think there really are apps that need to see forged RA's, but if they really want everything, they should use bpf or the like, just as they would need to do to receive, for example, packets with invalid checksums. +-DLS - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] IPv6: optionaly validate RAs on raw sockets
Rémi Denis-Courmont wrote: > On Wednesday 11 July 2007 15:29:16 YOSHIFUJI Hideaki / 吉藤英明 wrote: >> In article <[EMAIL PROTECTED]> (at Tue, 10 Jul 2007 > 21:11:17 +0300), Remi Denis-Courmont <[EMAIL PROTECTED]> says: >>> ICMPv6 Router Advertisements may now contain informations that is >>> mostly of interest to userland. This currently mostly consists of >>> recursive DNS server addresses (though one should expect other >>> stuff to come). >> I really do not want to have such non-standard API in kernel. > > I can only think of a very limited set of ways to extract options from RAs > that the kernel currently ignores: > > 1) parse everything in kernel addrconf.c > 2) validate RA in kernel, parse userland options in userland Yes, #2 is the right option. However, I agree that passing such info with non-standard socket option is not ideal. Since you asked for another idea, how about using netlink to send _validated_ RA information to interested parties? -vlad - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] IPv6: optionaly validate RAs on raw sockets
> Since you asked for another idea, how about using netlink to send _validated_ RA > information to interested parties? > > -vlad That sounds like a good idea to me (FWIW), though I also still think a simple raw-socket application would do it just fine, possibly with no kernel modification at all. But since the kernel wouldn't be maintaining the DNS info, which was my real objection to the original version, netlink would work well too. +-DLS - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] IPv6: optionaly validate RAs on raw sockets
Le mercredi 11 juillet 2007, David Stevens a écrit : > That sounds like a good idea to me (FWIW), > though I also still think a simple raw-socket > application would do it just fine, possibly with > no kernel modification at all. > But since the kernel wouldn't be maintaining > the DNS info, which was my real objection to the > original version, netlink would work well too. One remaining corner case is NFS/IPv6 root, whereby userland won't have a chance to start before the network, and hence may miss the solicited RA. Or would it? By default, the next unsolicited RA can be anytime from now to after 10 minutes, so that's not sufficient. I wouldn't personnaly care, but... -- Rémi Denis-Courmont http://www.remlab.net/ - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] IPv6: optionaly validate RAs on raw sockets
Rémi Denis-Courmont wrote: > Le mercredi 11 juillet 2007, David Stevens a écrit : >> That sounds like a good idea to me (FWIW), >> though I also still think a simple raw-socket >> application would do it just fine, possibly with >> no kernel modification at all. >> But since the kernel wouldn't be maintaining >> the DNS info, which was my real objection to the >> original version, netlink would work well too. > > One remaining corner case is NFS/IPv6 root, whereby userland won't have > a chance to start before the network, and hence may miss the solicited > RA. Or would it? By default, the next unsolicited RA can be anytime > from now to after 10 minutes, so that's not sufficient. I wouldn't > personnaly care, but... > You've got the same issue with the socket option approach. -vlad - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] IPv6: optionaly validate RAs on raw sockets
From: Rémi_Denis-Courmont <[EMAIL PROTECTED]> Date: Wed, 11 Jul 2007 19:19:11 +0300 > Le mercredi 11 juillet 2007, David Stevens a écrit : > > That sounds like a good idea to me (FWIW), > > though I also still think a simple raw-socket > > application would do it just fine, possibly with > > no kernel modification at all. > > But since the kernel wouldn't be maintaining > > the DNS info, which was my real objection to the > > original version, netlink would work well too. > > One remaining corner case is NFS/IPv6 root, whereby userland won't have > a chance to start before the network, and hence may miss the solicited > RA. Or would it? By default, the next unsolicited RA can be anytime > from now to after 10 minutes, so that's not sufficient. I wouldn't > personnaly care, but... We already have cases like that with network device firmware that has to be loaded in from the filesystem in userspace, and the answer is to use a properly populated initrd. Same goes for things like this. That's the fact of life these days, like it or not. - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] IPv6: optionaly validate RAs on raw sockets
On Wed, 11 Jul 2007, David Miller wrote: > > One remaining corner case is NFS/IPv6 root, whereby userland won't have > > a chance to start before the network, and hence may miss the solicited > > RA. Or would it? By default, the next unsolicited RA can be anytime > > from now to after 10 minutes, so that's not sufficient. I wouldn't > > personnaly care, but... > > We already have cases like that with network device firmware that > has to be loaded in from the filesystem in userspace, and the > answer is to use a properly populated initrd. > > Same goes for things like this. > > That's the fact of life these days, like it or not. Same story for NFS root when using strong authentication -- something has to be running in userland to manage that. - James -- James Morris <[EMAIL PROTECTED]> - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
