Commit ba5ea614 authored by Linus Lüssing's avatar Linus Lüssing Committed by David S. Miller
Browse files

bridge: simplify ip_mc_check_igmp() and ipv6_mc_check_mld() calls 



This patch refactors ip_mc_check_igmp(), ipv6_mc_check_mld() and
their callers (more precisely, the Linux bridge) to not rely on
the skb_trimmed parameter anymore.

An skb with its tail trimmed to the IP packet length was initially
introduced for the following three reasons:

1) To be able to verify the ICMPv6 checksum.
2) To be able to distinguish the version of an IGMP or MLD query.
   They are distinguishable only by their size.
3) To avoid parsing data for an IGMPv3 or MLDv2 report that is
   beyond the IP packet but still within the skb.

The first case still uses a cloned and potentially trimmed skb to
verfiy. However, there is no need to propagate it to the caller.
For the second and third case explicit IP packet length checks were
added.

This hopefully makes ip_mc_check_igmp() and ipv6_mc_check_mld() easier
to read and verfiy, as well as easier to use.

Signed-off-by: default avatarLinus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6679cf09

include/linux/igmp.h

+10 −1
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <linux/skbuff.h>

#include <linux/timer.h>

#include <linux/in.h>

#include <linux/ip.h>

#include <linux/refcount.h>

#include <uapi/linux/igmp.h>
@@ -106,6 +107,14 @@ struct ip_mc_list { 
#define IGMPV3_QQIC(value) IGMPV3_EXP(0x80, 4, 3, value)

#define IGMPV3_MRC(value) IGMPV3_EXP(0x80, 4, 3, value)



static inline int ip_mc_may_pull(struct sk_buff *skb, unsigned int len)

{

	if (skb_transport_offset(skb) + ip_transport_len(skb) < len)

		return -EINVAL;



	return pskb_may_pull(skb, len);

}



extern int ip_check_mc_rcu(struct in_device *dev, __be32 mc_addr, __be32 src_addr, u8 proto);

extern int igmp_rcv(struct sk_buff *);

extern int ip_mc_join_group(struct sock *sk, struct ip_mreqn *imr);
@@ -130,6 +139,6 @@ extern void ip_mc_unmap(struct in_device *); 
extern void ip_mc_remap(struct in_device *);

extern void ip_mc_dec_group(struct in_device *in_dev, __be32 addr);

extern void ip_mc_inc_group(struct in_device *in_dev, __be32 addr);

int ip_mc_check_igmp(struct sk_buff *skb, struct sk_buff **skb_trimmed);

int ip_mc_check_igmp(struct sk_buff *skb);



#endif

include/linux/ip.h

+5 −0
Original line number Diff line number Diff line
@@ -34,4 +34,9 @@ static inline struct iphdr *ipip_hdr(const struct sk_buff *skb) 
{

	return (struct iphdr *)skb_transport_header(skb);

}



static inline unsigned int ip_transport_len(const struct sk_buff *skb)

{

	return ntohs(ip_hdr(skb)->tot_len) - skb_network_header_len(skb);

}

#endif	/* _LINUX_IP_H */

include/linux/ipv6.h

+6 −0
Original line number Diff line number Diff line
@@ -104,6 +104,12 @@ static inline struct ipv6hdr *ipipv6_hdr(const struct sk_buff *skb) 
	return (struct ipv6hdr *)skb_transport_header(skb);

}



static inline unsigned int ipv6_transport_len(const struct sk_buff *skb)

{

	return ntohs(ipv6_hdr(skb)->payload_len) + sizeof(struct ipv6hdr) -

	       skb_network_header_len(skb);

}



/* 

   This structure contains results of exthdrs parsing

   as offsets from skb->nh.

include/net/addrconf.h

+11 −1
Original line number Diff line number Diff line
@@ -49,6 +49,7 @@ struct prefix_info { 
	struct in6_addr		prefix;

};



#include <linux/ipv6.h>

#include <linux/netdevice.h>

#include <net/if_inet6.h>

#include <net/ipv6.h>
@@ -201,6 +202,15 @@ u32 ipv6_addr_label(struct net *net, const struct in6_addr *addr, 
/*

 *	multicast prototypes (mcast.c)

 */

static inline int ipv6_mc_may_pull(struct sk_buff *skb,

				   unsigned int len)

{

	if (skb_transport_offset(skb) + ipv6_transport_len(skb) < len)

		return -EINVAL;



	return pskb_may_pull(skb, len);

}



int ipv6_sock_mc_join(struct sock *sk, int ifindex,

		      const struct in6_addr *addr);

int ipv6_sock_mc_drop(struct sock *sk, int ifindex,
@@ -219,7 +229,7 @@ void ipv6_mc_unmap(struct inet6_dev *idev); 
void ipv6_mc_remap(struct inet6_dev *idev);

void ipv6_mc_init_dev(struct inet6_dev *idev);

void ipv6_mc_destroy_dev(struct inet6_dev *idev);

int ipv6_mc_check_mld(struct sk_buff *skb, struct sk_buff **skb_trimmed);

int ipv6_mc_check_mld(struct sk_buff *skb);

void addrconf_dad_failure(struct sk_buff *skb, struct inet6_ifaddr *ifp);



bool ipv6_chk_mcast_addr(struct net_device *dev, const struct in6_addr *group,

net/batman-adv/multicast.c

+2 −2
Original line number Diff line number Diff line
@@ -674,7 +674,7 @@ static void batadv_mcast_mla_update(struct work_struct *work) 
 */

static bool batadv_mcast_is_report_ipv4(struct sk_buff *skb)

{

	if (ip_mc_check_igmp(skb, NULL) < 0)

	if (ip_mc_check_igmp(skb) < 0)

		return false;



	switch (igmp_hdr(skb)->type) {
@@ -741,7 +741,7 @@ static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv, 
 */

static bool batadv_mcast_is_report_ipv6(struct sk_buff *skb)

{

	if (ipv6_mc_check_mld(skb, NULL) < 0)

	if (ipv6_mc_check_mld(skb) < 0)

		return false;



	switch (icmp6_hdr(skb)->icmp6_type) {

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