From e18503f41f9b12132c95d7c31ca6ee5155e44e5c Mon Sep 17 00:00:00 2001 From: =?utf8?q?Fran=C3=A7ois=20Cachereul?= Date: Wed, 2 Oct 2013 10:16:02 +0200 Subject: [PATCH] l2tp: fix kernel panic when using IPv4-mapped IPv6 addresses MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit IPv4 mapped addresses cause kernel panic. The patch juste check whether the IPv6 address is an IPv4 mapped address. If so, use IPv4 API instead of IPv6. [ 940.026915] general protection fault: 0000 [#1] [ 940.026915] Modules linked in: l2tp_ppp l2tp_netlink l2tp_core pppox ppp_generic slhc loop psmouse [ 940.026915] CPU: 0 PID: 3184 Comm: memcheck-amd64- Not tainted 3.11.0+ #1 [ 940.026915] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007 [ 940.026915] task: ffff880007130e20 ti: ffff88000737e000 task.ti: ffff88000737e000 [ 940.026915] RIP: 0010:[] [] ip6_xmit+0x276/0x326 [ 940.026915] RSP: 0018:ffff88000737fd28 EFLAGS: 00010286 [ 940.026915] RAX: c748521a75ceff48 RBX: ffff880000c30800 RCX: 0000000000000000 [ 940.026915] RDX: ffff88000075cc4e RSI: 0000000000000028 RDI: ffff8800060e5a40 [ 940.026915] RBP: ffff8800060e5a40 R08: 0000000000000000 R09: ffff88000075cc90 [ 940.026915] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88000737fda0 [ 940.026915] R13: 0000000000000000 R14: 0000000000002000 R15: ffff880005d3b580 [ 940.026915] FS: 00007f163dc5e800(0000) GS:ffffffff81623000(0000) knlGS:0000000000000000 [ 940.026915] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 940.026915] CR2: 00000004032dc940 CR3: 0000000005c25000 CR4: 00000000000006f0 [ 940.026915] Stack: [ 940.026915] ffff88000075cc4e ffffffff81694e90 ffff880000c30b38 0000000000000020 [ 940.026915] 11000000523c4bac ffff88000737fdb4 0000000000000000 ffff880000c30800 [ 940.026915] ffff880005d3b580 ffff880000c30b38 ffff8800060e5a40 0000000000000020 [ 940.026915] Call Trace: [ 940.026915] [] ? inet6_csk_xmit+0xa4/0xc4 [ 940.026915] [] ? l2tp_xmit_skb+0x503/0x55a [l2tp_core] [ 940.026915] [] ? pskb_expand_head+0x161/0x214 [ 940.026915] [] ? pppol2tp_xmit+0xf2/0x143 [l2tp_ppp] [ 940.026915] [] ? ppp_channel_push+0x36/0x8b [ppp_generic] [ 940.026915] [] ? ppp_write+0xaf/0xc5 [ppp_generic] [ 940.026915] [] ? vfs_write+0xa2/0x106 [ 940.026915] [] ? SyS_write+0x56/0x8a [ 940.026915] [] ? system_call_fastpath+0x16/0x1b [ 940.026915] Code: 00 49 8b 8f d8 00 00 00 66 83 7c 11 02 00 74 60 49 8b 47 58 48 83 e0 fe 48 8b 80 18 01 00 00 48 85 c0 74 13 48 8b 80 78 02 00 00 <48> ff 40 28 41 8b 57 68 48 01 50 30 48 8b 54 24 08 49 c7 c1 51 [ 940.026915] RIP [] ip6_xmit+0x276/0x326 [ 940.026915] RSP [ 940.057945] ---[ end trace be8aba9a61c8b7f3 ]--- [ 940.058583] Kernel panic - not syncing: Fatal exception in interrupt Signed-off-by: François CACHEREUL Signed-off-by: David S. Miller --- net/l2tp/l2tp_core.c | 27 +++++++++++++++++++++++---- net/l2tp/l2tp_core.h | 3 +++ 2 files changed, 26 insertions(+), 4 deletions(-) diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index feae495a0a30..aedaa2cd4237 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -496,6 +496,7 @@ out: static inline int l2tp_verify_udp_checksum(struct sock *sk, struct sk_buff *skb) { + struct l2tp_tunnel *tunnel = (struct l2tp_tunnel *)sk->sk_user_data; struct udphdr *uh = udp_hdr(skb); u16 ulen = ntohs(uh->len); __wsum psum; @@ -504,7 +505,7 @@ static inline int l2tp_verify_udp_checksum(struct sock *sk, return 0; #if IS_ENABLED(CONFIG_IPV6) - if (sk->sk_family == PF_INET6) { + if (sk->sk_family == PF_INET6 && !tunnel->v4mapped) { if (!uh->check) { LIMIT_NETDEBUG(KERN_INFO "L2TP: IPv6: checksum is 0\n"); return 1; @@ -1128,7 +1129,7 @@ static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, /* Queue the packet to IP for output */ skb->local_df = 1; #if IS_ENABLED(CONFIG_IPV6) - if (skb->sk->sk_family == PF_INET6) + if (skb->sk->sk_family == PF_INET6 && !tunnel->v4mapped) error = inet6_csk_xmit(skb, NULL); else #endif @@ -1255,7 +1256,7 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len /* Calculate UDP checksum if configured to do so */ #if IS_ENABLED(CONFIG_IPV6) - if (sk->sk_family == PF_INET6) + if (sk->sk_family == PF_INET6 && !tunnel->v4mapped) l2tp_xmit_ipv6_csum(sk, skb, udp_len); else #endif @@ -1704,6 +1705,24 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 if (cfg != NULL) tunnel->debug = cfg->debug; +#if IS_ENABLED(CONFIG_IPV6) + if (sk->sk_family == PF_INET6) { + struct ipv6_pinfo *np = inet6_sk(sk); + + if (ipv6_addr_v4mapped(&np->saddr) && + ipv6_addr_v4mapped(&np->daddr)) { + struct inet_sock *inet = inet_sk(sk); + + tunnel->v4mapped = true; + inet->inet_saddr = np->saddr.s6_addr32[3]; + inet->inet_rcv_saddr = np->rcv_saddr.s6_addr32[3]; + inet->inet_daddr = np->daddr.s6_addr32[3]; + } else { + tunnel->v4mapped = false; + } + } +#endif + /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */ tunnel->encap = encap; if (encap == L2TP_ENCAPTYPE_UDP) { @@ -1712,7 +1731,7 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv; udp_sk(sk)->encap_destroy = l2tp_udp_encap_destroy; #if IS_ENABLED(CONFIG_IPV6) - if (sk->sk_family == PF_INET6) + if (sk->sk_family == PF_INET6 && !tunnel->v4mapped) udpv6_encap_enable(); else #endif diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h index 66a559b104b6..6f251cbc2ed7 100644 --- a/net/l2tp/l2tp_core.h +++ b/net/l2tp/l2tp_core.h @@ -194,6 +194,9 @@ struct l2tp_tunnel { struct sock *sock; /* Parent socket */ int fd; /* Parent fd, if tunnel socket * was created by userspace */ +#if IS_ENABLED(CONFIG_IPV6) + bool v4mapped; +#endif struct work_struct del_work; -- 2.20.1