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linux_dsm_epyc7002/net/ipv6/icmp.c
Jason A. Donenfeld ce4feb0111 net: icmp: pass zeroed opts from icmp{,v6}_ndo_send before sending 
commit ee576c47db60432c37e54b1e2b43a8ca6d3a8dca upstream.

The icmp{,v6}_send functions make all sorts of use of skb->cb, casting
it with IPCB or IP6CB, assuming the skb to have come directly from the
inet layer. But when the packet comes from the ndo layer, especially
when forwarded, there's no telling what might be in skb->cb at that
point. As a result, the icmp sending code risks reading bogus memory
contents, which can result in nasty stack overflows such as this one
reported by a user:

    panic+0x108/0x2ea
    __stack_chk_fail+0x14/0x20
    __icmp_send+0x5bd/0x5c0
    icmp_ndo_send+0x148/0x160

In icmp_send, skb->cb is cast with IPCB and an ip_options struct is read
from it. The optlen parameter there is of particular note, as it can
induce writes beyond bounds. There are quite a few ways that can happen
in __ip_options_echo. For example:

    // sptr/skb are attacker-controlled skb bytes
    sptr = skb_network_header(skb);
    // dptr/dopt points to stack memory allocated by __icmp_send
    dptr = dopt->__data;
    // sopt is the corrupt skb->cb in question
    if (sopt->rr) {
        optlen  = sptr[sopt->rr+1]; // corrupt skb->cb + skb->data
        soffset = sptr[sopt->rr+2]; // corrupt skb->cb + skb->data
	// this now writes potentially attacker-controlled data, over
	// flowing the stack:
        memcpy(dptr, sptr+sopt->rr, optlen);
    }

In the icmpv6_send case, the story is similar, but not as dire, as only
IP6CB(skb)->iif and IP6CB(skb)->dsthao are used. The dsthao case is
worse than the iif case, but it is passed to ipv6_find_tlv, which does
a bit of bounds checking on the value.

This is easy to simulate by doing a `memset(skb->cb, 0x41,
sizeof(skb->cb));` before calling icmp{,v6}_ndo_send, and it's only by
good fortune and the rarity of icmp sending from that context that we've
avoided reports like this until now. For example, in KASAN:

    BUG: KASAN: stack-out-of-bounds in __ip_options_echo+0xa0e/0x12b0
    Write of size 38 at addr ffff888006f1f80e by task ping/89
    CPU: 2 PID: 89 Comm: ping Not tainted 5.10.0-rc7-debug+ #5
    Call Trace:
     dump_stack+0x9a/0xcc
     print_address_description.constprop.0+0x1a/0x160
     __kasan_report.cold+0x20/0x38
     kasan_report+0x32/0x40
     check_memory_region+0x145/0x1a0
     memcpy+0x39/0x60
     __ip_options_echo+0xa0e/0x12b0
     __icmp_send+0x744/0x1700

Actually, out of the 4 drivers that do this, only gtp zeroed the cb for
the v4 case, while the rest did not. So this commit actually removes the
gtp-specific zeroing, while putting the code where it belongs in the
shared infrastructure of icmp{,v6}_ndo_send.

This commit fixes the issue by passing an empty IPCB or IP6CB along to
the functions that actually do the work. For the icmp_send, this was
already trivial, thanks to __icmp_send providing the plumbing function.
For icmpv6_send, this required a tiny bit of refactoring to make it
behave like the v4 case, after which it was straight forward.

Fixes: a2b78e9b2c ("sunvnet: generate ICMP PTMUD messages for smaller port MTUs")
Reported-by: SinYu <liuxyon@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/netdev/CAF=yD-LOF116aHub6RMe8vB8ZpnrrnoTdqhobEx+bvoA8AsP0w@mail.gmail.com/T/
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Link: https://lore.kernel.org/r/20210223131858.72082-1-Jason@zx2c4.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-04 11:38:46 +01:00

1218 lines
28 KiB
C
Raw Blame History

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Internet Control Message Protocol (ICMPv6)
* Linux INET6 implementation
*
* Authors:
* Pedro Roque <roque@di.fc.ul.pt>
*
* Based on net/ipv4/icmp.c
*
* RFC 1885
*/
/*
* Changes:
*
* Andi Kleen : exception handling
* Andi Kleen add rate limits. never reply to a icmp.
* add more length checks and other fixes.
* yoshfuji : ensure to sent parameter problem for
* fragments.
* YOSHIFUJI Hideaki @USAGI: added sysctl for icmp rate limit.
* Randy Dunlap and
* YOSHIFUJI Hideaki @USAGI: Per-interface statistics support
* Kazunori MIYAZAWA @USAGI: change output process to use ip6_append_data
*/
#define pr_fmt(fmt) "IPv6: " fmt
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/netfilter.h>
#include <linux/slab.h>
#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
#endif
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/icmpv6.h>
#include <net/ip.h>
#include <net/sock.h>
#include <net/ipv6.h>
#include <net/ip6_checksum.h>
#include <net/ping.h>
#include <net/protocol.h>
#include <net/raw.h>
#include <net/rawv6.h>
#include <net/transp_v6.h>
#include <net/ip6_route.h>
#include <net/addrconf.h>
#include <net/icmp.h>
#include <net/xfrm.h>
#include <net/inet_common.h>
#include <net/dsfield.h>
#include <net/l3mdev.h>
#include <linux/uaccess.h>
/*
* The ICMP socket(s). This is the most convenient way to flow control
* our ICMP output as well as maintain a clean interface throughout
* all layers. All Socketless IP sends will soon be gone.
*
* On SMP we have one ICMP socket per-cpu.
*/
static struct sock *icmpv6_sk(struct net *net)
{
return this_cpu_read(*net->ipv6.icmp_sk);
}
static int icmpv6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
u8 type, u8 code, int offset, __be32 info)
{
/* icmpv6_notify checks 8 bytes can be pulled, icmp6hdr is 8 bytes */
struct icmp6hdr *icmp6 = (struct icmp6hdr *) (skb->data + offset);
struct net *net = dev_net(skb->dev);
if (type == ICMPV6_PKT_TOOBIG)
ip6_update_pmtu(skb, net, info, skb->dev->ifindex, 0, sock_net_uid(net, NULL));
else if (type == NDISC_REDIRECT)
ip6_redirect(skb, net, skb->dev->ifindex, 0,
sock_net_uid(net, NULL));
if (!(type & ICMPV6_INFOMSG_MASK))
if (icmp6->icmp6_type == ICMPV6_ECHO_REQUEST)
ping_err(skb, offset, ntohl(info));
return 0;
}
static int icmpv6_rcv(struct sk_buff *skb);
static const struct inet6_protocol icmpv6_protocol = {
.handler = icmpv6_rcv,
.err_handler = icmpv6_err,
.flags = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
};
/* Called with BH disabled */
static __inline__ struct sock *icmpv6_xmit_lock(struct net *net)
{
struct sock *sk;
sk = icmpv6_sk(net);
if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
/* This can happen if the output path (f.e. SIT or
* ip6ip6 tunnel) signals dst_link_failure() for an
* outgoing ICMP6 packet.
*/
return NULL;
}
return sk;
}
static __inline__ void icmpv6_xmit_unlock(struct sock *sk)
{
spin_unlock(&sk->sk_lock.slock);
}
/*
* Figure out, may we reply to this packet with icmp error.
*
* We do not reply, if:
* - it was icmp error message.
* - it is truncated, so that it is known, that protocol is ICMPV6
* (i.e. in the middle of some exthdr)
*
* --ANK (980726)
*/
static bool is_ineligible(const struct sk_buff *skb)
{
int ptr = (u8 *)(ipv6_hdr(skb) + 1) - skb->data;
int len = skb->len - ptr;
__u8 nexthdr = ipv6_hdr(skb)->nexthdr;
__be16 frag_off;
if (len < 0)
return true;
ptr = ipv6_skip_exthdr(skb, ptr, &nexthdr, &frag_off);
if (ptr < 0)
return false;
if (nexthdr == IPPROTO_ICMPV6) {
u8 _type, *tp;
tp = skb_header_pointer(skb,
ptr+offsetof(struct icmp6hdr, icmp6_type),
sizeof(_type), &_type);
/* Based on RFC 8200, Section 4.5 Fragment Header, return
* false if this is a fragment packet with no icmp header info.
*/
if (!tp && frag_off != 0)
return false;
else if (!tp || !(*tp & ICMPV6_INFOMSG_MASK))
return true;
}
return false;
}
static bool icmpv6_mask_allow(struct net *net, int type)
{
if (type > ICMPV6_MSG_MAX)
return true;
/* Limit if icmp type is set in ratemask. */
if (!test_bit(type, net->ipv6.sysctl.icmpv6_ratemask))
return true;
return false;
}
static bool icmpv6_global_allow(struct net *net, int type)
{
if (icmpv6_mask_allow(net, type))
return true;
if (icmp_global_allow())
return true;
return false;
}
/*
* Check the ICMP output rate limit
*/
static bool icmpv6_xrlim_allow(struct sock *sk, u8 type,
struct flowi6 *fl6)
{
struct net *net = sock_net(sk);
struct dst_entry *dst;
bool res = false;
if (icmpv6_mask_allow(net, type))
return true;
/*
* Look up the output route.
* XXX: perhaps the expire for routing entries cloned by
* this lookup should be more aggressive (not longer than timeout).
*/
dst = ip6_route_output(net, sk, fl6);
if (dst->error) {
IP6_INC_STATS(net, ip6_dst_idev(dst),
IPSTATS_MIB_OUTNOROUTES);
} else if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) {
res = true;
} else {
struct rt6_info *rt = (struct rt6_info *)dst;
int tmo = net->ipv6.sysctl.icmpv6_time;
struct inet_peer *peer;
/* Give more bandwidth to wider prefixes. */
if (rt->rt6i_dst.plen < 128)
tmo >>= ((128 - rt->rt6i_dst.plen)>>5);
peer = inet_getpeer_v6(net->ipv6.peers, &fl6->daddr, 1);
res = inet_peer_xrlim_allow(peer, tmo);
if (peer)
inet_putpeer(peer);
}
dst_release(dst);
return res;
}
static bool icmpv6_rt_has_prefsrc(struct sock *sk, u8 type,
struct flowi6 *fl6)
{
struct net *net = sock_net(sk);
struct dst_entry *dst;
bool res = false;
dst = ip6_route_output(net, sk, fl6);
if (!dst->error) {
struct rt6_info *rt = (struct rt6_info *)dst;
struct in6_addr prefsrc;
rt6_get_prefsrc(rt, &prefsrc);
res = !ipv6_addr_any(&prefsrc);
}
dst_release(dst);
return res;
}
/*
* an inline helper for the "simple" if statement below
* checks if parameter problem report is caused by an
* unrecognized IPv6 option that has the Option Type
* highest-order two bits set to 10
*/
static bool opt_unrec(struct sk_buff *skb, __u32 offset)
{
u8 _optval, *op;
offset += skb_network_offset(skb);
op = skb_header_pointer(skb, offset, sizeof(_optval), &_optval);
if (!op)
return true;
return (*op & 0xC0) == 0x80;
}
void icmpv6_push_pending_frames(struct sock *sk, struct flowi6 *fl6,
struct icmp6hdr *thdr, int len)
{
struct sk_buff *skb;
struct icmp6hdr *icmp6h;
skb = skb_peek(&sk->sk_write_queue);
if (!skb)
return;
icmp6h = icmp6_hdr(skb);
memcpy(icmp6h, thdr, sizeof(struct icmp6hdr));
icmp6h->icmp6_cksum = 0;
if (skb_queue_len(&sk->sk_write_queue) == 1) {
skb->csum = csum_partial(icmp6h,
sizeof(struct icmp6hdr), skb->csum);
icmp6h->icmp6_cksum = csum_ipv6_magic(&fl6->saddr,
&fl6->daddr,
len, fl6->flowi6_proto,
skb->csum);
} else {
__wsum tmp_csum = 0;
skb_queue_walk(&sk->sk_write_queue, skb) {
tmp_csum = csum_add(tmp_csum, skb->csum);
}
tmp_csum = csum_partial(icmp6h,
sizeof(struct icmp6hdr), tmp_csum);
icmp6h->icmp6_cksum = csum_ipv6_magic(&fl6->saddr,
&fl6->daddr,
len, fl6->flowi6_proto,
tmp_csum);
}
ip6_push_pending_frames(sk);
}
struct icmpv6_msg {
struct sk_buff *skb;
int offset;
uint8_t type;
};
static int icmpv6_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
{
struct icmpv6_msg *msg = (struct icmpv6_msg *) from;
struct sk_buff *org_skb = msg->skb;
__wsum csum;
csum = skb_copy_and_csum_bits(org_skb, msg->offset + offset,
to, len);
skb->csum = csum_block_add(skb->csum, csum, odd);
if (!(msg->type & ICMPV6_INFOMSG_MASK))
nf_ct_attach(skb, org_skb);
return 0;
}
#if IS_ENABLED(CONFIG_IPV6_MIP6)
static void mip6_addr_swap(struct sk_buff *skb, const struct inet6_skb_parm *opt)
{
struct ipv6hdr *iph = ipv6_hdr(skb);
struct ipv6_destopt_hao *hao;
struct in6_addr tmp;
int off;
if (opt->dsthao) {
off = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
if (likely(off >= 0)) {
hao = (struct ipv6_destopt_hao *)
(skb_network_header(skb) + off);
tmp = iph->saddr;
iph->saddr = hao->addr;
hao->addr = tmp;
}
}
}
#else
static inline void mip6_addr_swap(struct sk_buff *skb, const struct inet6_skb_parm *opt) {}
#endif
static struct dst_entry *icmpv6_route_lookup(struct net *net,
struct sk_buff *skb,
struct sock *sk,
struct flowi6 *fl6)
{
struct dst_entry *dst, *dst2;
struct flowi6 fl2;
int err;
err = ip6_dst_lookup(net, sk, &dst, fl6);
if (err)
return ERR_PTR(err);
/*
* We won't send icmp if the destination is known
* anycast.
*/
if (ipv6_anycast_destination(dst, &fl6->daddr)) {
net_dbg_ratelimited("icmp6_send: acast source\n");
dst_release(dst);
return ERR_PTR(-EINVAL);
}
/* No need to clone since we're just using its address. */
dst2 = dst;
dst = xfrm_lookup(net, dst, flowi6_to_flowi(fl6), sk, 0);
if (!IS_ERR(dst)) {
if (dst != dst2)
return dst;
} else {
if (PTR_ERR(dst) == -EPERM)
dst = NULL;
else
return dst;
}
err = xfrm_decode_session_reverse(skb, flowi6_to_flowi(&fl2), AF_INET6);
if (err)
goto relookup_failed;
err = ip6_dst_lookup(net, sk, &dst2, &fl2);
if (err)
goto relookup_failed;
dst2 = xfrm_lookup(net, dst2, flowi6_to_flowi(&fl2), sk, XFRM_LOOKUP_ICMP);
if (!IS_ERR(dst2)) {
dst_release(dst);
dst = dst2;
} else {
err = PTR_ERR(dst2);
if (err == -EPERM) {
dst_release(dst);
return dst2;
} else
goto relookup_failed;
}
relookup_failed:
if (dst)
return dst;
return ERR_PTR(err);
}
static struct net_device *icmp6_dev(const struct sk_buff *skb)
{
struct net_device *dev = skb->dev;
/* for local traffic to local address, skb dev is the loopback
* device. Check if there is a dst attached to the skb and if so
* get the real device index. Same is needed for replies to a link
* local address on a device enslaved to an L3 master device
*/
if (unlikely(dev->ifindex == LOOPBACK_IFINDEX || netif_is_l3_master(skb->dev))) {
const struct rt6_info *rt6 = skb_rt6_info(skb);
if (rt6)
dev = rt6->rt6i_idev->dev;
}
return dev;
}
static int icmp6_iif(const struct sk_buff *skb)
{
return icmp6_dev(skb)->ifindex;
}
/*
* Send an ICMP message in response to a packet in error
*/
void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info,
const struct in6_addr *force_saddr,
const struct inet6_skb_parm *parm)
{
struct inet6_dev *idev = NULL;
struct ipv6hdr *hdr = ipv6_hdr(skb);
struct sock *sk;
struct net *net;
struct ipv6_pinfo *np;
const struct in6_addr *saddr = NULL;
struct dst_entry *dst;
struct icmp6hdr tmp_hdr;
struct flowi6 fl6;
struct icmpv6_msg msg;
struct ipcm6_cookie ipc6;
int iif = 0;
int addr_type = 0;
int len;
u32 mark;
if ((u8 *)hdr < skb->head ||
(skb_network_header(skb) + sizeof(*hdr)) > skb_tail_pointer(skb))
return;
if (!skb->dev)
return;
net = dev_net(skb->dev);
mark = IP6_REPLY_MARK(net, skb->mark);
/*
* Make sure we respect the rules
* i.e. RFC 1885 2.4(e)
* Rule (e.1) is enforced by not using icmp6_send
* in any code that processes icmp errors.
*/
addr_type = ipv6_addr_type(&hdr->daddr);
if (ipv6_chk_addr(net, &hdr->daddr, skb->dev, 0) ||
ipv6_chk_acast_addr_src(net, skb->dev, &hdr->daddr))
saddr = &hdr->daddr;
/*
* Dest addr check
*/
if (addr_type & IPV6_ADDR_MULTICAST || skb->pkt_type != PACKET_HOST) {
if (type != ICMPV6_PKT_TOOBIG &&
!(type == ICMPV6_PARAMPROB &&
code == ICMPV6_UNK_OPTION &&
(opt_unrec(skb, info))))
return;
saddr = NULL;
}
addr_type = ipv6_addr_type(&hdr->saddr);
/*
* Source addr check
*/
if (__ipv6_addr_needs_scope_id(addr_type)) {
iif = icmp6_iif(skb);
} else {
/*
* The source device is used for looking up which routing table
* to use for sending an ICMP error.
*/
iif = l3mdev_master_ifindex(skb->dev);
}
/*
* Must not send error if the source does not uniquely
* identify a single node (RFC2463 Section 2.4).
* We check unspecified / multicast addresses here,
* and anycast addresses will be checked later.
*/
if ((addr_type == IPV6_ADDR_ANY) || (addr_type & IPV6_ADDR_MULTICAST)) {
net_dbg_ratelimited("icmp6_send: addr_any/mcast source [%pI6c > %pI6c]\n",
&hdr->saddr, &hdr->daddr);
return;
}
/*
* Never answer to a ICMP packet.
*/
if (is_ineligible(skb)) {
net_dbg_ratelimited("icmp6_send: no reply to icmp error [%pI6c > %pI6c]\n",
&hdr->saddr, &hdr->daddr);
return;
}
/* Needed by both icmp_global_allow and icmpv6_xmit_lock */
local_bh_disable();
/* Check global sysctl_icmp_msgs_per_sec ratelimit */
if (!(skb->dev->flags & IFF_LOOPBACK) && !icmpv6_global_allow(net, type))
goto out_bh_enable;
mip6_addr_swap(skb, parm);
sk = icmpv6_xmit_lock(net);
if (!sk)
goto out_bh_enable;
memset(&fl6, 0, sizeof(fl6));
fl6.flowi6_proto = IPPROTO_ICMPV6;
fl6.daddr = hdr->saddr;
if (force_saddr)
saddr = force_saddr;
if (saddr) {
fl6.saddr = *saddr;
} else if (!icmpv6_rt_has_prefsrc(sk, type, &fl6)) {
/* select a more meaningful saddr from input if */
struct net_device *in_netdev;
in_netdev = dev_get_by_index(net, parm->iif);
if (in_netdev) {
ipv6_dev_get_saddr(net, in_netdev, &fl6.daddr,
inet6_sk(sk)->srcprefs,
&fl6.saddr);
dev_put(in_netdev);
}
}
fl6.flowi6_mark = mark;
fl6.flowi6_oif = iif;
fl6.fl6_icmp_type = type;
fl6.fl6_icmp_code = code;
fl6.flowi6_uid = sock_net_uid(net, NULL);
fl6.mp_hash = rt6_multipath_hash(net, &fl6, skb, NULL);
security_skb_classify_flow(skb, flowi6_to_flowi(&fl6));
np = inet6_sk(sk);
if (!icmpv6_xrlim_allow(sk, type, &fl6))
goto out;
tmp_hdr.icmp6_type = type;
tmp_hdr.icmp6_code = code;
tmp_hdr.icmp6_cksum = 0;
tmp_hdr.icmp6_pointer = htonl(info);
if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
fl6.flowi6_oif = np->mcast_oif;
else if (!fl6.flowi6_oif)
fl6.flowi6_oif = np->ucast_oif;
ipcm6_init_sk(&ipc6, np);
ipc6.sockc.mark = mark;
fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
dst = icmpv6_route_lookup(net, skb, sk, &fl6);
if (IS_ERR(dst))
goto out;
ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
msg.skb = skb;
msg.offset = skb_network_offset(skb);
msg.type = type;
len = skb->len - msg.offset;
len = min_t(unsigned int, len, IPV6_MIN_MTU - sizeof(struct ipv6hdr) - sizeof(struct icmp6hdr));
if (len < 0) {
net_dbg_ratelimited("icmp: len problem [%pI6c > %pI6c]\n",
&hdr->saddr, &hdr->daddr);
goto out_dst_release;
}
rcu_read_lock();
idev = __in6_dev_get(skb->dev);
if (ip6_append_data(sk, icmpv6_getfrag, &msg,
len + sizeof(struct icmp6hdr),
sizeof(struct icmp6hdr),
&ipc6, &fl6, (struct rt6_info *)dst,
MSG_DONTWAIT)) {
ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTERRORS);
ip6_flush_pending_frames(sk);
} else {
icmpv6_push_pending_frames(sk, &fl6, &tmp_hdr,
len + sizeof(struct icmp6hdr));
}
rcu_read_unlock();
out_dst_release:
dst_release(dst);
out:
icmpv6_xmit_unlock(sk);
out_bh_enable:
local_bh_enable();
}
EXPORT_SYMBOL(icmp6_send);
/* Slightly more convenient version of icmp6_send.
*/
void icmpv6_param_prob(struct sk_buff *skb, u8 code, int pos)
{
icmp6_send(skb, ICMPV6_PARAMPROB, code, pos, NULL, IP6CB(skb));
kfree_skb(skb);
}
/* Generate icmpv6 with type/code ICMPV6_DEST_UNREACH/ICMPV6_ADDR_UNREACH
* if sufficient data bytes are available
* @nhs is the size of the tunnel header(s) :
* Either an IPv4 header for SIT encap
* an IPv4 header + GRE header for GRE encap
*/
int ip6_err_gen_icmpv6_unreach(struct sk_buff *skb, int nhs, int type,
unsigned int data_len)
{
struct in6_addr temp_saddr;
struct rt6_info *rt;
struct sk_buff *skb2;
u32 info = 0;
if (!pskb_may_pull(skb, nhs + sizeof(struct ipv6hdr) + 8))
return 1;
/* RFC 4884 (partial) support for ICMP extensions */
if (data_len < 128 || (data_len & 7) || skb->len < data_len)
data_len = 0;
skb2 = data_len ? skb_copy(skb, GFP_ATOMIC) : skb_clone(skb, GFP_ATOMIC);
if (!skb2)
return 1;
skb_dst_drop(skb2);
skb_pull(skb2, nhs);
skb_reset_network_header(skb2);
rt = rt6_lookup(dev_net(skb->dev), &ipv6_hdr(skb2)->saddr, NULL, 0,
skb, 0);
if (rt && rt->dst.dev)
skb2->dev = rt->dst.dev;
ipv6_addr_set_v4mapped(ip_hdr(skb)->saddr, &temp_saddr);
if (data_len) {
/* RFC 4884 (partial) support :
* insert 0 padding at the end, before the extensions
*/
__skb_push(skb2, nhs);
skb_reset_network_header(skb2);
memmove(skb2->data, skb2->data + nhs, data_len - nhs);
memset(skb2->data + data_len - nhs, 0, nhs);
/* RFC 4884 4.5 : Length is measured in 64-bit words,
* and stored in reserved[0]
*/
info = (data_len/8) << 24;
}
if (type == ICMP_TIME_EXCEEDED)
icmp6_send(skb2, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
info, &temp_saddr, IP6CB(skb2));
else
icmp6_send(skb2, ICMPV6_DEST_UNREACH, ICMPV6_ADDR_UNREACH,
info, &temp_saddr, IP6CB(skb2));
if (rt)
ip6_rt_put(rt);
kfree_skb(skb2);
return 0;
}
EXPORT_SYMBOL(ip6_err_gen_icmpv6_unreach);
static void icmpv6_echo_reply(struct sk_buff *skb)
{
struct net *net = dev_net(skb->dev);
struct sock *sk;
struct inet6_dev *idev;
struct ipv6_pinfo *np;
const struct in6_addr *saddr = NULL;
struct icmp6hdr *icmph = icmp6_hdr(skb);
struct icmp6hdr tmp_hdr;
struct flowi6 fl6;
struct icmpv6_msg msg;
struct dst_entry *dst;
struct ipcm6_cookie ipc6;
u32 mark = IP6_REPLY_MARK(net, skb->mark);
bool acast;
if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) &&
net->ipv6.sysctl.icmpv6_echo_ignore_multicast)
return;
saddr = &ipv6_hdr(skb)->daddr;
acast = ipv6_anycast_destination(skb_dst(skb), saddr);
if (acast && net->ipv6.sysctl.icmpv6_echo_ignore_anycast)
return;
if (!ipv6_unicast_destination(skb) &&
!(net->ipv6.sysctl.anycast_src_echo_reply && acast))
saddr = NULL;
memcpy(&tmp_hdr, icmph, sizeof(tmp_hdr));
tmp_hdr.icmp6_type = ICMPV6_ECHO_REPLY;
memset(&fl6, 0, sizeof(fl6));
if (net->ipv6.sysctl.flowlabel_reflect & FLOWLABEL_REFLECT_ICMPV6_ECHO_REPLIES)
fl6.flowlabel = ip6_flowlabel(ipv6_hdr(skb));
fl6.flowi6_proto = IPPROTO_ICMPV6;
fl6.daddr = ipv6_hdr(skb)->saddr;
if (saddr)
fl6.saddr = *saddr;
fl6.flowi6_oif = icmp6_iif(skb);
fl6.fl6_icmp_type = ICMPV6_ECHO_REPLY;
fl6.flowi6_mark = mark;
fl6.flowi6_uid = sock_net_uid(net, NULL);
security_skb_classify_flow(skb, flowi6_to_flowi(&fl6));
local_bh_disable();
sk = icmpv6_xmit_lock(net);
if (!sk)
goto out_bh_enable;
np = inet6_sk(sk);
if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
fl6.flowi6_oif = np->mcast_oif;
else if (!fl6.flowi6_oif)
fl6.flowi6_oif = np->ucast_oif;
if (ip6_dst_lookup(net, sk, &dst, &fl6))
goto out;
dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0);
if (IS_ERR(dst))
goto out;
/* Check the ratelimit */
if ((!(skb->dev->flags & IFF_LOOPBACK) && !icmpv6_global_allow(net, ICMPV6_ECHO_REPLY)) ||
!icmpv6_xrlim_allow(sk, ICMPV6_ECHO_REPLY, &fl6))
goto out_dst_release;
idev = __in6_dev_get(skb->dev);
msg.skb = skb;
msg.offset = 0;
msg.type = ICMPV6_ECHO_REPLY;
ipcm6_init_sk(&ipc6, np);
ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
ipc6.tclass = ipv6_get_dsfield(ipv6_hdr(skb));
ipc6.sockc.mark = mark;
if (ip6_append_data(sk, icmpv6_getfrag, &msg,
skb->len + sizeof(struct icmp6hdr),
sizeof(struct icmp6hdr), &ipc6, &fl6,
(struct rt6_info *)dst, MSG_DONTWAIT)) {
__ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTERRORS);
ip6_flush_pending_frames(sk);
} else {
icmpv6_push_pending_frames(sk, &fl6, &tmp_hdr,
skb->len + sizeof(struct icmp6hdr));
}
out_dst_release:
dst_release(dst);
out:
icmpv6_xmit_unlock(sk);
out_bh_enable:
local_bh_enable();
}
void icmpv6_notify(struct sk_buff *skb, u8 type, u8 code, __be32 info)
{
const struct inet6_protocol *ipprot;
int inner_offset;
__be16 frag_off;
u8 nexthdr;
struct net *net = dev_net(skb->dev);
if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
goto out;
nexthdr = ((struct ipv6hdr *)skb->data)->nexthdr;
if (ipv6_ext_hdr(nexthdr)) {
/* now skip over extension headers */
inner_offset = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr),
&nexthdr, &frag_off);
if (inner_offset < 0)
goto out;
} else {
inner_offset = sizeof(struct ipv6hdr);
}
/* Checkin header including 8 bytes of inner protocol header. */
if (!pskb_may_pull(skb, inner_offset+8))
goto out;
/* BUGGG_FUTURE: we should try to parse exthdrs in this packet.
Without this we will not able f.e. to make source routed
pmtu discovery.
Corresponding argument (opt) to notifiers is already added.
--ANK (980726)
*/
ipprot = rcu_dereference(inet6_protos[nexthdr]);
if (ipprot && ipprot->err_handler)
ipprot->err_handler(skb, NULL, type, code, inner_offset, info);
raw6_icmp_error(skb, nexthdr, type, code, inner_offset, info);
return;
out:
__ICMP6_INC_STATS(net, __in6_dev_get(skb->dev), ICMP6_MIB_INERRORS);
}
/*
* Handle icmp messages
*/
static int icmpv6_rcv(struct sk_buff *skb)
{
struct net *net = dev_net(skb->dev);
struct net_device *dev = icmp6_dev(skb);
struct inet6_dev *idev = __in6_dev_get(dev);
const struct in6_addr *saddr, *daddr;
struct icmp6hdr *hdr;
u8 type;
bool success = false;
if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
struct sec_path *sp = skb_sec_path(skb);
int nh;
if (!(sp && sp->xvec[sp->len - 1]->props.flags &
XFRM_STATE_ICMP))
goto drop_no_count;
if (!pskb_may_pull(skb, sizeof(*hdr) + sizeof(struct ipv6hdr)))
goto drop_no_count;
nh = skb_network_offset(skb);
skb_set_network_header(skb, sizeof(*hdr));
if (!xfrm6_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
goto drop_no_count;
skb_set_network_header(skb, nh);
}
__ICMP6_INC_STATS(dev_net(dev), idev, ICMP6_MIB_INMSGS);
saddr = &ipv6_hdr(skb)->saddr;
daddr = &ipv6_hdr(skb)->daddr;
if (skb_checksum_validate(skb, IPPROTO_ICMPV6, ip6_compute_pseudo)) {
net_dbg_ratelimited("ICMPv6 checksum failed [%pI6c > %pI6c]\n",
saddr, daddr);
goto csum_error;
}
if (!pskb_pull(skb, sizeof(*hdr)))
goto discard_it;
hdr = icmp6_hdr(skb);
type = hdr->icmp6_type;
ICMP6MSGIN_INC_STATS(dev_net(dev), idev, type);
switch (type) {
case ICMPV6_ECHO_REQUEST:
if (!net->ipv6.sysctl.icmpv6_echo_ignore_all)
icmpv6_echo_reply(skb);
break;
case ICMPV6_ECHO_REPLY:
success = ping_rcv(skb);
break;
case ICMPV6_PKT_TOOBIG:
/* BUGGG_FUTURE: if packet contains rthdr, we cannot update
standard destination cache. Seems, only "advanced"
destination cache will allow to solve this problem
--ANK (980726)
*/
if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
goto discard_it;
hdr = icmp6_hdr(skb);
/* to notify */
fallthrough;
case ICMPV6_DEST_UNREACH:
case ICMPV6_TIME_EXCEED:
case ICMPV6_PARAMPROB:
icmpv6_notify(skb, type, hdr->icmp6_code, hdr->icmp6_mtu);
break;
case NDISC_ROUTER_SOLICITATION:
case NDISC_ROUTER_ADVERTISEMENT:
case NDISC_NEIGHBOUR_SOLICITATION:
case NDISC_NEIGHBOUR_ADVERTISEMENT:
case NDISC_REDIRECT:
ndisc_rcv(skb);
break;
case ICMPV6_MGM_QUERY:
igmp6_event_query(skb);
break;
case ICMPV6_MGM_REPORT:
igmp6_event_report(skb);
break;
case ICMPV6_MGM_REDUCTION:
case ICMPV6_NI_QUERY:
case ICMPV6_NI_REPLY:
case ICMPV6_MLD2_REPORT:
case ICMPV6_DHAAD_REQUEST:
case ICMPV6_DHAAD_REPLY:
case ICMPV6_MOBILE_PREFIX_SOL:
case ICMPV6_MOBILE_PREFIX_ADV:
break;
default:
/* informational */
if (type & ICMPV6_INFOMSG_MASK)
break;
net_dbg_ratelimited("icmpv6: msg of unknown type [%pI6c > %pI6c]\n",
saddr, daddr);
/*
* error of unknown type.
* must pass to upper level
*/
icmpv6_notify(skb, type, hdr->icmp6_code, hdr->icmp6_mtu);
}
/* until the v6 path can be better sorted assume failure and
* preserve the status quo behaviour for the rest of the paths to here
*/
if (success)
consume_skb(skb);
else
kfree_skb(skb);
return 0;
csum_error:
__ICMP6_INC_STATS(dev_net(dev), idev, ICMP6_MIB_CSUMERRORS);
discard_it:
__ICMP6_INC_STATS(dev_net(dev), idev, ICMP6_MIB_INERRORS);
drop_no_count:
kfree_skb(skb);
return 0;
}
void icmpv6_flow_init(struct sock *sk, struct flowi6 *fl6,
u8 type,
const struct in6_addr *saddr,
const struct in6_addr *daddr,
int oif)
{
memset(fl6, 0, sizeof(*fl6));
fl6->saddr = *saddr;
fl6->daddr = *daddr;
fl6->flowi6_proto = IPPROTO_ICMPV6;
fl6->fl6_icmp_type = type;
fl6->fl6_icmp_code = 0;
fl6->flowi6_oif = oif;
security_sk_classify_flow(sk, flowi6_to_flowi(fl6));
}
static void __net_exit icmpv6_sk_exit(struct net *net)
{
int i;
for_each_possible_cpu(i)
inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv6.icmp_sk, i));
free_percpu(net->ipv6.icmp_sk);
}
static int __net_init icmpv6_sk_init(struct net *net)
{
struct sock *sk;
int err, i;
net->ipv6.icmp_sk = alloc_percpu(struct sock *);
if (!net->ipv6.icmp_sk)
return -ENOMEM;
for_each_possible_cpu(i) {
err = inet_ctl_sock_create(&sk, PF_INET6,
SOCK_RAW, IPPROTO_ICMPV6, net);
if (err < 0) {
pr_err("Failed to initialize the ICMP6 control socket (err %d)\n",
err);
goto fail;
}
*per_cpu_ptr(net->ipv6.icmp_sk, i) = sk;
/* Enough space for 2 64K ICMP packets, including
* sk_buff struct overhead.
*/
sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
}
return 0;
fail:
icmpv6_sk_exit(net);
return err;
}
static struct pernet_operations icmpv6_sk_ops = {
.init = icmpv6_sk_init,
.exit = icmpv6_sk_exit,
};
int __init icmpv6_init(void)
{
int err;
err = register_pernet_subsys(&icmpv6_sk_ops);
if (err < 0)
return err;
err = -EAGAIN;
if (inet6_add_protocol(&icmpv6_protocol, IPPROTO_ICMPV6) < 0)
goto fail;
err = inet6_register_icmp_sender(icmp6_send);
if (err)
goto sender_reg_err;
return 0;
sender_reg_err:
inet6_del_protocol(&icmpv6_protocol, IPPROTO_ICMPV6);
fail:
pr_err("Failed to register ICMP6 protocol\n");
unregister_pernet_subsys(&icmpv6_sk_ops);
return err;
}
void icmpv6_cleanup(void)
{
inet6_unregister_icmp_sender(icmp6_send);
unregister_pernet_subsys(&icmpv6_sk_ops);
inet6_del_protocol(&icmpv6_protocol, IPPROTO_ICMPV6);
}
static const struct icmp6_err {
int err;
int fatal;
} tab_unreach[] = {
{ /* NOROUTE */
.err = ENETUNREACH,
.fatal = 0,
},
{ /* ADM_PROHIBITED */
.err = EACCES,
.fatal = 1,
},
{ /* Was NOT_NEIGHBOUR, now reserved */
.err = EHOSTUNREACH,
.fatal = 0,
},
{ /* ADDR_UNREACH */
.err = EHOSTUNREACH,
.fatal = 0,
},
{ /* PORT_UNREACH */
.err = ECONNREFUSED,
.fatal = 1,
},
{ /* POLICY_FAIL */
.err = EACCES,
.fatal = 1,
},
{ /* REJECT_ROUTE */
.err = EACCES,
.fatal = 1,
},
};
int icmpv6_err_convert(u8 type, u8 code, int *err)
{
int fatal = 0;
*err = EPROTO;
switch (type) {
case ICMPV6_DEST_UNREACH:
fatal = 1;
if (code < ARRAY_SIZE(tab_unreach)) {
*err = tab_unreach[code].err;
fatal = tab_unreach[code].fatal;
}
break;
case ICMPV6_PKT_TOOBIG:
*err = EMSGSIZE;
break;
case ICMPV6_PARAMPROB:
*err = EPROTO;
fatal = 1;
break;
case ICMPV6_TIME_EXCEED:
*err = EHOSTUNREACH;
break;
}
return fatal;
}
EXPORT_SYMBOL(icmpv6_err_convert);
#ifdef CONFIG_SYSCTL
static struct ctl_table ipv6_icmp_table_template[] = {
{
.procname = "ratelimit",
.data = &init_net.ipv6.sysctl.icmpv6_time,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_ms_jiffies,
},
{
.procname = "echo_ignore_all",
.data = &init_net.ipv6.sysctl.icmpv6_echo_ignore_all,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "echo_ignore_multicast",
.data = &init_net.ipv6.sysctl.icmpv6_echo_ignore_multicast,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "echo_ignore_anycast",
.data = &init_net.ipv6.sysctl.icmpv6_echo_ignore_anycast,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "ratemask",
.data = &init_net.ipv6.sysctl.icmpv6_ratemask_ptr,
.maxlen = ICMPV6_MSG_MAX + 1,
.mode = 0644,
.proc_handler = proc_do_large_bitmap,
},
{ },
};
struct ctl_table * __net_init ipv6_icmp_sysctl_init(struct net *net)
{
struct ctl_table *table;
table = kmemdup(ipv6_icmp_table_template,
sizeof(ipv6_icmp_table_template),
GFP_KERNEL);
if (table) {
table[0].data = &net->ipv6.sysctl.icmpv6_time;
table[1].data = &net->ipv6.sysctl.icmpv6_echo_ignore_all;
table[2].data = &net->ipv6.sysctl.icmpv6_echo_ignore_multicast;
table[3].data = &net->ipv6.sysctl.icmpv6_echo_ignore_anycast;
table[4].data = &net->ipv6.sysctl.icmpv6_ratemask_ptr;
}
return table;
}
#endif
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