Commit 628e341f authored by Hannes Frederic Sowa's avatar Hannes Frederic Sowa Committed by Steffen Klassert

xfrm: make local error reporting more robust

In xfrm4 and xfrm6 we need to take care about sockets of the other
address family. This could happen because a 6in4 or 4in6 tunnel could
get protected by ipsec.

Because we don't want to have a run-time dependency on ipv6 when only
using ipv4 xfrm we have to embed a pointer to the correct local_error
function in xfrm_state_afinet and look it up when returning an error
depending on the socket address family.

Thanks to vi0ss for the great bug report:

a) fix two more unsafe interpretations of skb->sk as ipv6 socket
   (xfrm6_local_dontfrag and __xfrm6_output)
a) add an EXPORT_SYMBOL_GPL(xfrm_local_error) to fix a link error when
   building ipv6 as a module (thanks to Steffen Klassert)

Reported-by: <>
Cc: Steffen Klassert <>
Signed-off-by: default avatarHannes Frederic Sowa <>
Signed-off-by: default avatarSteffen Klassert <>
parent d9bf5f13
......@@ -341,10 +341,13 @@ struct xfrm_state_afinfo {
struct sk_buff *skb);
int (*transport_finish)(struct sk_buff *skb,
int async);
void (*local_error)(struct sk_buff *skb, u32 mtu);
extern int xfrm_state_register_afinfo(struct xfrm_state_afinfo *afinfo);
extern int xfrm_state_unregister_afinfo(struct xfrm_state_afinfo *afinfo);
extern struct xfrm_state_afinfo *xfrm_state_get_afinfo(unsigned int family);
extern void xfrm_state_put_afinfo(struct xfrm_state_afinfo *afinfo);
extern void xfrm_state_delete_tunnel(struct xfrm_state *x);
......@@ -1477,6 +1480,7 @@ extern int xfrm_input_resume(struct sk_buff *skb, int nexthdr);
extern int xfrm_output_resume(struct sk_buff *skb, int err);
extern int xfrm_output(struct sk_buff *skb);
extern int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb);
extern void xfrm_local_error(struct sk_buff *skb, int mtu);
extern int xfrm4_extract_header(struct sk_buff *skb);
extern int xfrm4_extract_input(struct xfrm_state *x, struct sk_buff *skb);
extern int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
......@@ -1497,6 +1501,7 @@ extern int xfrm4_tunnel_register(struct xfrm_tunnel *handler, unsigned short fam
extern int xfrm4_tunnel_deregister(struct xfrm_tunnel *handler, unsigned short family);
extern int xfrm4_mode_tunnel_input_register(struct xfrm_tunnel *handler);
extern int xfrm4_mode_tunnel_input_deregister(struct xfrm_tunnel *handler);
extern void xfrm4_local_error(struct sk_buff *skb, u32 mtu);
extern int xfrm6_extract_header(struct sk_buff *skb);
extern int xfrm6_extract_input(struct xfrm_state *x, struct sk_buff *skb);
extern int xfrm6_rcv_spi(struct sk_buff *skb, int nexthdr, __be32 spi);
......@@ -1514,6 +1519,7 @@ extern int xfrm6_output(struct sk_buff *skb);
extern int xfrm6_output_finish(struct sk_buff *skb);
extern int xfrm6_find_1stfragopt(struct xfrm_state *x, struct sk_buff *skb,
u8 **prevhdr);
extern void xfrm6_local_error(struct sk_buff *skb, u32 mtu);
extern int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb);
......@@ -33,8 +33,7 @@ static int xfrm4_tunnel_check_size(struct sk_buff *skb)
mtu = dst_mtu(dst);
if (skb->len > mtu) {
if (skb->sk)
ip_local_error(skb->sk, EMSGSIZE, ip_hdr(skb)->daddr,
inet_sk(skb->sk)->inet_dport, mtu);
xfrm_local_error(skb, mtu);
icmp_send(skb, ICMP_DEST_UNREACH,
ICMP_FRAG_NEEDED, htonl(mtu));
......@@ -99,3 +98,12 @@ int xfrm4_output(struct sk_buff *skb)
!(IPCB(skb)->flags & IPSKB_REROUTED));
void xfrm4_local_error(struct sk_buff *skb, u32 mtu)
struct iphdr *hdr;
hdr = skb->encapsulation ? inner_ip_hdr(skb) : ip_hdr(skb);
ip_local_error(skb->sk, EMSGSIZE, hdr->daddr,
inet_sk(skb->sk)->inet_dport, mtu);
......@@ -83,6 +83,7 @@ static struct xfrm_state_afinfo xfrm4_state_afinfo = {
.extract_input = xfrm4_extract_input,
.extract_output = xfrm4_extract_output,
.transport_finish = xfrm4_transport_finish,
.local_error = xfrm4_local_error,
void __init xfrm4_state_init(void)
......@@ -34,8 +34,10 @@ static int xfrm6_local_dontfrag(struct sk_buff *skb)
struct sock *sk = skb->sk;
if (sk) {
proto = sk->sk_protocol;
if (sk->sk_family != AF_INET6)
return 0;
proto = sk->sk_protocol;
if (proto == IPPROTO_UDP || proto == IPPROTO_RAW)
return inet6_sk(sk)->dontfrag;
......@@ -54,7 +56,7 @@ static void xfrm6_local_rxpmtu(struct sk_buff *skb, u32 mtu)
ipv6_local_rxpmtu(sk, &fl6, mtu);
static void xfrm6_local_error(struct sk_buff *skb, u32 mtu)
void xfrm6_local_error(struct sk_buff *skb, u32 mtu)
struct flowi6 fl6;
struct sock *sk = skb->sk;
......@@ -80,7 +82,7 @@ static int xfrm6_tunnel_check_size(struct sk_buff *skb)
if (xfrm6_local_dontfrag(skb))
xfrm6_local_rxpmtu(skb, mtu);
else if (skb->sk)
xfrm6_local_error(skb, mtu);
xfrm_local_error(skb, mtu);
icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
ret = -EMSGSIZE;
......@@ -142,7 +144,7 @@ static int __xfrm6_output(struct sk_buff *skb)
xfrm6_local_rxpmtu(skb, mtu);
return -EMSGSIZE;
} else if (!skb->local_df && skb->len > mtu && skb->sk) {
xfrm6_local_error(skb, mtu);
xfrm_local_error(skb, mtu);
return -EMSGSIZE;
......@@ -183,6 +183,7 @@ static struct xfrm_state_afinfo xfrm6_state_afinfo = {
.extract_input = xfrm6_extract_input,
.extract_output = xfrm6_extract_output,
.transport_finish = xfrm6_transport_finish,
.local_error = xfrm6_local_error,
int __init xfrm6_state_init(void)
......@@ -214,5 +214,18 @@ int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
return inner_mode->afinfo->extract_output(x, skb);
void xfrm_local_error(struct sk_buff *skb, int mtu)
struct xfrm_state_afinfo *afinfo;
afinfo = xfrm_state_get_afinfo(skb->sk->sk_family);
if (!afinfo)
afinfo->local_error(skb, mtu);
......@@ -39,9 +39,6 @@ static DEFINE_SPINLOCK(xfrm_state_lock);
static unsigned int xfrm_state_hashmax __read_mostly = 1 * 1024 * 1024;
static struct xfrm_state_afinfo *xfrm_state_get_afinfo(unsigned int family);
static void xfrm_state_put_afinfo(struct xfrm_state_afinfo *afinfo);
static inline unsigned int xfrm_dst_hash(struct net *net,
const xfrm_address_t *daddr,
const xfrm_address_t *saddr,
......@@ -1860,7 +1857,7 @@ int xfrm_state_unregister_afinfo(struct xfrm_state_afinfo *afinfo)
static struct xfrm_state_afinfo *xfrm_state_get_afinfo(unsigned int family)
struct xfrm_state_afinfo *xfrm_state_get_afinfo(unsigned int family)
struct xfrm_state_afinfo *afinfo;
if (unlikely(family >= NPROTO))
......@@ -1872,7 +1869,7 @@ static struct xfrm_state_afinfo *xfrm_state_get_afinfo(unsigned int family)
return afinfo;
static void xfrm_state_put_afinfo(struct xfrm_state_afinfo *afinfo)
void xfrm_state_put_afinfo(struct xfrm_state_afinfo *afinfo)
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