14 Aug
2013
14 Aug
'13
1:38 p.m.
Hi,
On 10 August 2013 05:20, Antonio Quartulli <ordex(a)autistici.org> wrote:
I mostly took this function from another source file as it is, but it
was static so I couldn't use it directly.
I will make the changes.
I will resolve most of the comments when I redo the patch.
Thanks,
Mihail
On Mon, Jul 08, 2013 at 03:12:43AM +0300,
mihail.costea2005(a)gmail.com wrote:
Some of the code style problems were added by git mail it seems. In my
code the alignment is correct (I did you --strict).
But I didn't new comments should be :).
/**
*
*/
From: Mihail Costea
<mihail.costea90(a)gmail.com>
Adds functions needed for NDP snooping, like getting the IPv6 addresses
or getting the target HW address from an Neighbor Advertisement (NA).
typo: an -> a
Also added functions to create NA for Neighbor
Solicitations
use always the same form: added -> adds
that have already the HW address in DAT.
Signed-off-by: Mihail Costea <mihail.costea90(a)gmail.com>
Signed-off-by: Stefan Popa <Stefan.A.Popa(a)intel.com>
Reviewed-by: Stefan Popa <Stefan.A.Popa(a)intel.com>
---
distributed-arp-table.c | 319 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 319 insertions(+)
diff --git a/distributed-arp-table.c b/distributed-arp-table.c
index f941913..d0b9e95 100644
--- a/distributed-arp-table.c
+++ b/distributed-arp-table.c
@@ -20,7 +20,9 @@
#include <linux/if_ether.h>
#include <linux/if_arp.h>
#include <linux/if_vlan.h>
+#include <net/addrconf.h>
#include <net/arp.h>
+#include <net/ipv6.h>
#include "main.h"
#include "hash.h"
@@ -981,6 +983,323 @@ static unsigned short batadv_dat_get_vid(struct sk_buff *skb, int
*hdr_size)
return vid;
}
+#if IS_ENABLED(CONFIG_IPV6)
+/**
+ * batadv_ndisc_hw_src - get source hw address from a packet
+ * @skb: packet to check
+ * @hdr_size: size of the encapsulation header
+ *
+ * Returns source hw address of the skb packet.
+ */
+static uint8_t *batadv_ndisc_hw_src(struct sk_buff *skb, int hdr_size)
+{
+ struct ethhdr *ethhdr;
please put a blank line after variable declarations.
+ ethhdr = (struct ethhdr *)(skb->data +
hdr_size);
+ return (uint8_t *)ethhdr->h_source;
+}
+
+/**
+ * batadv_ndisc_hw_dst - get destination hw address from a packet
+ * @skb: packet to check
+ * @hdr_size: size of the encapsulation header
+ *
+ * Returns destination hw address of the skb packet.
+ */
+static uint8_t *batadv_ndisc_hw_dst(struct sk_buff *skb, int hdr_size)
+{
+ struct ethhdr *ethhdr;
same here
+ ethhdr = (struct ethhdr *)(skb->data +
hdr_size);
+ return (uint8_t *)ethhdr->h_dest;
+}
+
+/**
+ * batadv_ndisc_ipv6_src - get source IPv6 address from a packet
+ * @skb: packet to check
+ * @hdr_size: size of the encapsulation header
+ *
+ * Returns source IPv6 address of the skb packet.
+ */
+static struct in6_addr *batadv_ndisc_ipv6_src(struct sk_buff *skb,
+ int hdr_size)
+{
+ struct ipv6hdr *ipv6hdr;
same here
+ ipv6hdr = (struct ipv6hdr *)(skb->data +
hdr_size + ETH_HLEN);
+ return &ipv6hdr->saddr;
+}
+
+/**
+ * batadv_ndisc_ipv6_dst - get destination IPv6 address from a packet
+ * @skb: packet to check
+ * @hdr_size: size of the encapsulation header
+ *
+ * Returns destination IPv6 address of the skb packet.
+ */
+static struct in6_addr *batadv_ndisc_ipv6_dst(struct sk_buff *skb,
+ int hdr_size)
+{
+ struct ipv6hdr *ipv6hdr;
same here
+ ipv6hdr = (struct ipv6hdr *)(skb->data +
hdr_size + ETH_HLEN);
+ return &ipv6hdr->daddr;
+}
+
+/**
+ * batadv_ndisc_ipv6_target - get target IPv6 address from a NS/NA packet
+ * @skb: packet to check
+ * @hdr_size: size of the encapsulation header
+ *
+ * Returns target IPv6 address of the skb packet.
+ */
+static struct in6_addr *batadv_ndisc_ipv6_target(struct sk_buff *skb,
+ int hdr_size)
+{
+ return (struct in6_addr *)(skb->data + hdr_size + ETH_HLEN +
+ sizeof(struct ipv6hdr) + sizeof(struct icmp6hdr));
please, use the needed local variables to make this statement more readable and
and to align it in a proper way.
+}
+
+/**
+ * batadv_ndisc_hw_opt - get hw address from NS/NA packet options
+ * @skb: packet to check
+ * @hdr_size: size of the encapsulation header
+ * @type: type of the address (ND_OPT_SOURCE_LL_ADDR or ND_OPT_TARGET_LL_ADDR)
+ *
+ * The address can be either the source link-layer address
+ * or the target link-layer address.
+ * For more info see RFC2461.
+ *
+ * Returns hw address from packet options.
+ */
+static uint8_t *batadv_ndisc_hw_opt(struct sk_buff *skb, int hdr_size,
+ uint8_t type)
+{
+ unsigned char *opt_addr;
+
+ opt_addr = skb->data + hdr_size + ETH_HLEN +
+ sizeof(struct ipv6hdr) + sizeof(struct icmp6hdr) +
+ sizeof(struct in6_addr);
+
align this statement properly. it should be:
like_this = this + that +
and_whatever +
we_need;
+ /* test if option header is ok */
Please, be a bit more verbose in this comment. What are we checking here?
why != 1? What does that mean? Otherwise it will be difficult for other people
out of these patches business to understand
+ if (*opt_addr != type || *(opt_addr + 1) !=
1)
+ return NULL;
+ return (uint8_t *)(opt_addr + 2);
and why skipping the initial two bytes? Maybe you should describe what opt_addr
contains? this will probably help to better understand what this statement is
doing.
+}
+
+/**
+ * batadv_ndisc_get_type - get icmp6 packet type
I think you can directly call this function "batadv_icmpv6_get_type".
It may be re-used in the future for the same purpose but somewhere else :)
+ * @bat_priv: the bat priv with all the soft
interface information
+ * @skb: packet to check
+ * @hdr_size: size of the encapsulation header
+ *
+ * Returns the icmp6 type, or 0 if packet is not a valid icmp6 packet.
+ */
+static __u8 batadv_ndisc_get_type(struct batadv_priv *bat_priv,
in the batman-adv code we use stdint: __u8 -> uint8_t (there are other spots
where you use __8)
+ struct sk_buff
*skb, int hdr_size)
+{
+ struct ethhdr *ethhdr;
+ struct ipv6hdr *ipv6hdr;
+ struct icmp6hdr *icmp6hdr;
+ __u8 type = 0;
+
+ /* pull headers */
+ if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN +
+ sizeof(struct ipv6hdr) + sizeof(struct icmp6hdr))))
please properly align this statement too. I think checkpatch would have
complained about this. You can use tabs + spaces to correctly align.
+
goto out;
+
+ /* get the ethernet header */
remove this comment :) Variables are named properly and this is obvious.
+ ethhdr = (struct ethhdr *)(skb->data +
hdr_size);
+ if (ethhdr->h_proto != htons(ETH_P_IPV6))
+ goto out;
+
+ /* get the ipv6 header */
same
+ ipv6hdr = (struct ipv6hdr *)(skb->data +
hdr_size + ETH_HLEN);
+ if (ipv6hdr->nexthdr != IPPROTO_ICMPV6)
+ goto out;
+
+ /* get the icmpv6 header */
+ icmp6hdr = (struct icmp6hdr *)(skb->data + hdr_size + ETH_HLEN +
+ sizeof(struct ipv6hdr));
alignment..should line up to the opening parenthesis.
(blablabla *)(like
this);
+
+ /* check whether the ndisc packet carries a valid icmp6 header */
+ if (ipv6hdr->hop_limit != 255)
+ goto out;
+
+ if (icmp6hdr->icmp6_code != 0)
+ goto out;
+
+ type = icmp6hdr->icmp6_type;
+out:
+ return type;
+}
+
+/**
+ * batadv_ndisc_is_valid - check if a ndisc packet is valid
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: packet to check
+ * @hdr_size: size of the encapsulation header
+ * @ndisc_type: type of ndisc packet to check
+ *
+ * Check if all IPs are valid (source, destination, target) and if
+ * options hw address is valid too.
+ * Some options might be ignored, like NS packets sent automatically
+ * for verification of the reachability of a neighbor.
+ *
+ * Returns true if packet is valid, otherwise false if invalid or ignored.
+ */
+static bool batadv_ndisc_is_valid(struct batadv_priv *bat_priv,
+ struct sk_buff *skb, int hdr_size,
+ int ndisc_type)
+{
+ uint8_t *hw_target = NULL;
+ struct in6_addr *ipv6_src, *ipv6_dst, *ipv6_target;
+ __u8 type = batadv_ndisc_get_type(bat_priv, skb, hdr_size);
+ int ndisc_hdr_len = hdr_size + ETH_HLEN + sizeof(struct ipv6hdr) +
+ sizeof(struct icmp6hdr) + sizeof(struct in6_addr) +
+ 8; /* ndisc options length */
when the assignment is too long, please do it after the declarations. Improves
readability.
+
+ if (type != ndisc_type)
+ return false;
+ if (unlikely(!pskb_may_pull(skb, ndisc_hdr_len)))
+ return false;
+
+ /* Check for bad NA/NS. If the ndisc message is not sane, DAT
+ * will simply ignore it
+ */
+ if (type == NDISC_NEIGHBOUR_SOLICITATION)
+ hw_target = batadv_ndisc_hw_opt(skb, hdr_size,
+ ND_OPT_SOURCE_LL_ADDR);
+ else if (type == NDISC_NEIGHBOUR_ADVERTISEMENT)
+ hw_target = batadv_ndisc_hw_opt(skb, hdr_size,
+ ND_OPT_TARGET_LL_ADDR);
+
+ if (!hw_target || is_zero_ether_addr(hw_target) ||
+ is_multicast_ether_addr(hw_target))
+ return false;
+
+ ipv6_src = batadv_ndisc_ipv6_src(skb, hdr_size);
+ ipv6_dst = batadv_ndisc_ipv6_dst(skb, hdr_size);
+ ipv6_target = batadv_ndisc_ipv6_target(skb, hdr_size);
+ if (ipv6_addr_loopback(ipv6_src) || ipv6_addr_loopback(ipv6_dst) ||
+ ipv6_addr_is_multicast(ipv6_src) ||
+ ipv6_addr_is_multicast(ipv6_target))
+ return false;
+
+ /* ignore messages with unspecified address */
+ if (ipv6_addr_any(ipv6_src) || ipv6_addr_any(ipv6_dst) ||
+ ipv6_addr_any(ipv6_target))
+ return false;
+
+ /* ignore the verification of the reachability of a neighbor */
+ if (type == NDISC_NEIGHBOUR_SOLICITATION &&
+ !ipv6_addr_is_multicast(ipv6_dst))
+ return false;
+
+ return true;
+}
+
+static void batadv_ndisc_ip6_hdr(struct sock *sk, struct sk_buff *skb,
+ struct net_device *dev,
+ const struct in6_addr *ipv6_src,
+ const struct in6_addr *ipv6_dst,
+ int proto, int len)
alignment?
+{
+ struct ipv6_pinfo *np = inet6_sk(sk);
+ struct ipv6hdr *hdr;
+
+ skb->protocol = htons(ETH_P_IPV6);
+ skb->dev = dev;
+
+ skb_reset_network_header(skb);
+ skb_put(skb, sizeof(struct ipv6hdr));
+ hdr = ipv6_hdr(skb);
+
+ *(__be32 *)hdr = htonl(0x60000000);
What does this constant mean? you are writing on the IPv6 header?
why not writing in one of its fields (I guess you wanted to write in the first
one)?
+
+ hdr->payload_len = htons(len);
I think len can be declared int16_t to avoid using wrong values?
(here and where you call this function)
+ hdr->nexthdr = proto;
+ hdr->hop_limit = np->hop_limit;
+
+ hdr->saddr = *ipv6_src;
+ hdr->daddr = *ipv6_dst;
+}
+
+/**
+ * batadv_ndisc_create_na - create an NA for a solicited NS
+ * @net_device: the devices for which the packet is created
+ * @ipv6_dst: destination IPv6
+ * @ipv6_target: target IPv6 (same with source IPv6)
+ * @hw_dst: destination HW Address
+ * @hw_target: target HW Address (same with source HW Address)
+ * @router: 1 if target is a router, else 0
+ * @solicited: 1 if this is a solicited NA, else 0
+ * @override: 1 if the target entry should be override, else 0
+ *
+ * For more info see RFC2461.
If you want to cite the RFC think you should provide also a section?
The "Neighbor Discovery for IP Version 6" RFC is a bit too much is I only want
to understand what a NA or NS is and how the NA is created.
By the way, ok for reading the RFC, but I think you can write a bit more about
what the function is doing: e.g. create a new skb containing an NA which fields
are initialised with the value passed as argument. Seems obvious, but better
safe than sorry :) Kernel Doc is shown without the code if you compile it.
+ *
+ * Returns the newly created skb, otherwise NULL.
+ */
+static struct
+sk_buff *batadv_ndisc_create_na(struct net_device *dev,
+ const struct in6_addr *ipv6_dst,
+ const struct in6_addr *ipv6_target,
+ const uint8_t *hw_dst,
+ const uint8_t *hw_target,
+ int router, int solicited, int override)
if these variables can only be 0 or 1, why not using bool?
+{
+ struct net *net = dev_net(dev);
+ struct sock *sk = net->ipv6.ndisc_sk;
+ struct sk_buff *skb;
+ struct icmp6hdr *icmp6hdr;
+ int hlen = LL_RESERVED_SPACE(dev);
+ int tlen = dev->needed_tailroom;
+ int len, err;
+ u8 *opt;
uint8_t
+
+ /* alloc space for skb */
+ len = sizeof(struct icmp6hdr) + sizeof(*ipv6_target) + 8;
write in the comment what is this 8. Otherwise, since you use it more than once,
create a define with a descriptive name and it instead of the 8.
+ skb = sock_alloc_send_skb(sk,
+ (MAX_HEADER + sizeof(struct ipv6hdr) +
why these parenthesis here?
+ len + hlen +
tlen),
I guess hlen is ETH_HLEN? what does LL_RESERVED_SPACE exactly return?
and why using needed_tailroom? what does it comport in this case?
We never used that during SKB allocation...this is why I am asking.
+ 1, &err);
and why are you using this function to allocate the skb? In the rest of the code
we always use netdev_alloc_skb_ip_align() (that also takes care of properly
aligning the skb).
+ if (!skb)
+ return NULL;
+
+ skb_reserve(skb, hlen);
+ batadv_ndisc_ip6_hdr(sk, skb, dev, ipv6_target, ipv6_dst,
+ IPPROTO_ICMPV6, len);
+
+ skb->transport_header = skb->tail;
why you care about setting the transport header?
You could also use skb_set_transport_header() passing a proper offset rather
than directly using skb->tail. Following the skb logic is "sometimes" not
straightforward, therefore it is better to use the provided functions when
possible.
+ skb_put(skb, len);
+
+ /* fill the device header for the NA frame */
+ if (dev_hard_header(skb, dev, ETH_P_IPV6, hw_dst,
+ hw_target, skb->len) < 0) {
+ kfree_skb(skb);
+ return NULL;
+ }
mh..we never used this function as we assume that the interface below batman-adv
is carrying 802.3 frame only. But looks interesting :)
+
+ /* set icmpv6 header */
+ icmp6hdr = (struct icmp6hdr *)skb_transport_header(skb);
ah now I understood why you have set the transport_header :)
+ icmp6hdr->icmp6_type =
NDISC_NEIGHBOUR_ADVERTISEMENT;
+ icmp6hdr->icmp6_router = router;
+ icmp6hdr->icmp6_solicited = solicited;
+ icmp6hdr->icmp6_override = override;
+
+ /* set NA target and options */
+ opt = skb_transport_header(skb) + sizeof(*icmp6hdr);
+ *(struct in6_addr *)opt = *ipv6_target;
+ opt += sizeof(*ipv6_target);
+
+ opt[0] = ND_OPT_TARGET_LL_ADDR;
+ opt[1] = 1;
+ memcpy(opt + 2, hw_target, dev->addr_len);
ah, these are the famous 8 bytes :) So hard to discover! :D
+
+ icmp6hdr->icmp6_cksum = csum_ipv6_magic(ipv6_target, ipv6_dst, len,
+ IPPROTO_ICMPV6,
+ csum_partial(icmp6hdr, len, 0));
+
+ return skb;
+}
+#endif
+
/**
* batadv_dat_snoop_outgoing_pkt_request - snoop the ARP request and try to
* answer using DAT
--
1.7.10.4
--
Antonio Quartulli
..each of us alone is worth nothing..
Ernesto "Che" Guevara