linux-stable/net/ipv6/seg6_iptunnel.c
David Lebrun fa79581ea6 ipv6: sr: fix several BUGs when preemption is enabled
When CONFIG_PREEMPT=y, CONFIG_IPV6=m and CONFIG_SEG6_HMAC=y,
seg6_hmac_init() is called during the initialization of the ipv6 module.
This causes a subsequent call to smp_processor_id() with preemption
enabled, resulting in the following trace.

[   20.451460] BUG: using smp_processor_id() in preemptible [00000000] code: systemd/1
[   20.452556] caller is debug_smp_processor_id+0x17/0x19
[   20.453304] CPU: 0 PID: 1 Comm: systemd Not tainted 4.9.0-rc5-00973-g46738b1 #1
[   20.454406]  ffffc9000062fc18 ffffffff813607b2 0000000000000000 ffffffff81a7f782
[   20.455528]  ffffc9000062fc48 ffffffff813778dc 0000000000000000 00000000001dcf98
[   20.456539]  ffffffffa003bd08 ffffffff81af93e0 ffffc9000062fc58 ffffffff81377905
[   20.456539] Call Trace:
[   20.456539]  [<ffffffff813607b2>] dump_stack+0x63/0x7f
[   20.456539]  [<ffffffff813778dc>] check_preemption_disabled+0xd1/0xe3
[   20.456539]  [<ffffffff81377905>] debug_smp_processor_id+0x17/0x19
[   20.460260]  [<ffffffffa0061f3b>] seg6_hmac_init+0xfa/0x192 [ipv6]
[   20.460260]  [<ffffffffa0061ccc>] seg6_init+0x39/0x6f [ipv6]
[   20.460260]  [<ffffffffa006121a>] inet6_init+0x21a/0x321 [ipv6]
[   20.460260]  [<ffffffffa0061000>] ? 0xffffffffa0061000
[   20.460260]  [<ffffffff81000457>] do_one_initcall+0x8b/0x115
[   20.460260]  [<ffffffff811328a3>] do_init_module+0x53/0x1c4
[   20.460260]  [<ffffffff8110650a>] load_module+0x1153/0x14ec
[   20.460260]  [<ffffffff81106a7b>] SYSC_finit_module+0x8c/0xb9
[   20.460260]  [<ffffffff81106a7b>] ? SYSC_finit_module+0x8c/0xb9
[   20.460260]  [<ffffffff81106abc>] SyS_finit_module+0x9/0xb
[   20.460260]  [<ffffffff810014d1>] do_syscall_64+0x62/0x75
[   20.460260]  [<ffffffff816834f0>] entry_SYSCALL64_slow_path+0x25/0x25

Moreover, dst_cache_* functions also call smp_processor_id(), generating
a similar trace.

This patch uses raw_cpu_ptr() in seg6_hmac_init() rather than this_cpu_ptr()
and disable preemption when using dst_cache_* functions.

Signed-off-by: David Lebrun <david.lebrun@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-13 12:29:55 -05:00

435 lines
9.5 KiB
C

/*
* SR-IPv6 implementation
*
* Author:
* David Lebrun <david.lebrun@uclouvain.be>
*
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/types.h>
#include <linux/skbuff.h>
#include <linux/net.h>
#include <linux/module.h>
#include <net/ip.h>
#include <net/lwtunnel.h>
#include <net/netevent.h>
#include <net/netns/generic.h>
#include <net/ip6_fib.h>
#include <net/route.h>
#include <net/seg6.h>
#include <linux/seg6.h>
#include <linux/seg6_iptunnel.h>
#include <net/addrconf.h>
#include <net/ip6_route.h>
#ifdef CONFIG_DST_CACHE
#include <net/dst_cache.h>
#endif
#ifdef CONFIG_IPV6_SEG6_HMAC
#include <net/seg6_hmac.h>
#endif
struct seg6_lwt {
#ifdef CONFIG_DST_CACHE
struct dst_cache cache;
#endif
struct seg6_iptunnel_encap tuninfo[0];
};
static inline struct seg6_lwt *seg6_lwt_lwtunnel(struct lwtunnel_state *lwt)
{
return (struct seg6_lwt *)lwt->data;
}
static inline struct seg6_iptunnel_encap *
seg6_encap_lwtunnel(struct lwtunnel_state *lwt)
{
return seg6_lwt_lwtunnel(lwt)->tuninfo;
}
static const struct nla_policy seg6_iptunnel_policy[SEG6_IPTUNNEL_MAX + 1] = {
[SEG6_IPTUNNEL_SRH] = { .type = NLA_BINARY },
};
int nla_put_srh(struct sk_buff *skb, int attrtype,
struct seg6_iptunnel_encap *tuninfo)
{
struct seg6_iptunnel_encap *data;
struct nlattr *nla;
int len;
len = SEG6_IPTUN_ENCAP_SIZE(tuninfo);
nla = nla_reserve(skb, attrtype, len);
if (!nla)
return -EMSGSIZE;
data = nla_data(nla);
memcpy(data, tuninfo, len);
return 0;
}
static void set_tun_src(struct net *net, struct net_device *dev,
struct in6_addr *daddr, struct in6_addr *saddr)
{
struct seg6_pernet_data *sdata = seg6_pernet(net);
struct in6_addr *tun_src;
rcu_read_lock();
tun_src = rcu_dereference(sdata->tun_src);
if (!ipv6_addr_any(tun_src)) {
memcpy(saddr, tun_src, sizeof(struct in6_addr));
} else {
ipv6_dev_get_saddr(net, dev, daddr, IPV6_PREFER_SRC_PUBLIC,
saddr);
}
rcu_read_unlock();
}
/* encapsulate an IPv6 packet within an outer IPv6 header with a given SRH */
static int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh)
{
struct net *net = dev_net(skb_dst(skb)->dev);
struct ipv6hdr *hdr, *inner_hdr;
struct ipv6_sr_hdr *isrh;
int hdrlen, tot_len, err;
hdrlen = (osrh->hdrlen + 1) << 3;
tot_len = hdrlen + sizeof(*hdr);
err = pskb_expand_head(skb, tot_len, 0, GFP_ATOMIC);
if (unlikely(err))
return err;
inner_hdr = ipv6_hdr(skb);
skb_push(skb, tot_len);
skb_reset_network_header(skb);
skb_mac_header_rebuild(skb);
hdr = ipv6_hdr(skb);
/* inherit tc, flowlabel and hlim
* hlim will be decremented in ip6_forward() afterwards and
* decapsulation will overwrite inner hlim with outer hlim
*/
ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)),
ip6_flowlabel(inner_hdr));
hdr->hop_limit = inner_hdr->hop_limit;
hdr->nexthdr = NEXTHDR_ROUTING;
isrh = (void *)hdr + sizeof(*hdr);
memcpy(isrh, osrh, hdrlen);
isrh->nexthdr = NEXTHDR_IPV6;
hdr->daddr = isrh->segments[isrh->first_segment];
set_tun_src(net, skb->dev, &hdr->daddr, &hdr->saddr);
#ifdef CONFIG_IPV6_SEG6_HMAC
if (sr_has_hmac(isrh)) {
err = seg6_push_hmac(net, &hdr->saddr, isrh);
if (unlikely(err))
return err;
}
#endif
skb_postpush_rcsum(skb, hdr, tot_len);
return 0;
}
/* insert an SRH within an IPv6 packet, just after the IPv6 header */
#ifdef CONFIG_IPV6_SEG6_INLINE
static int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh)
{
struct ipv6hdr *hdr, *oldhdr;
struct ipv6_sr_hdr *isrh;
int hdrlen, err;
hdrlen = (osrh->hdrlen + 1) << 3;
err = pskb_expand_head(skb, hdrlen, 0, GFP_ATOMIC);
if (unlikely(err))
return err;
oldhdr = ipv6_hdr(skb);
skb_pull(skb, sizeof(struct ipv6hdr));
skb_postpull_rcsum(skb, skb_network_header(skb),
sizeof(struct ipv6hdr));
skb_push(skb, sizeof(struct ipv6hdr) + hdrlen);
skb_reset_network_header(skb);
skb_mac_header_rebuild(skb);
hdr = ipv6_hdr(skb);
memmove(hdr, oldhdr, sizeof(*hdr));
isrh = (void *)hdr + sizeof(*hdr);
memcpy(isrh, osrh, hdrlen);
isrh->nexthdr = hdr->nexthdr;
hdr->nexthdr = NEXTHDR_ROUTING;
isrh->segments[0] = hdr->daddr;
hdr->daddr = isrh->segments[isrh->first_segment];
#ifdef CONFIG_IPV6_SEG6_HMAC
if (sr_has_hmac(isrh)) {
struct net *net = dev_net(skb_dst(skb)->dev);
err = seg6_push_hmac(net, &hdr->saddr, isrh);
if (unlikely(err))
return err;
}
#endif
skb_postpush_rcsum(skb, hdr, sizeof(struct ipv6hdr) + hdrlen);
return 0;
}
#endif
static int seg6_do_srh(struct sk_buff *skb)
{
struct dst_entry *dst = skb_dst(skb);
struct seg6_iptunnel_encap *tinfo;
int err = 0;
tinfo = seg6_encap_lwtunnel(dst->lwtstate);
if (likely(!skb->encapsulation)) {
skb_reset_inner_headers(skb);
skb->encapsulation = 1;
}
switch (tinfo->mode) {
#ifdef CONFIG_IPV6_SEG6_INLINE
case SEG6_IPTUN_MODE_INLINE:
err = seg6_do_srh_inline(skb, tinfo->srh);
skb_reset_inner_headers(skb);
break;
#endif
case SEG6_IPTUN_MODE_ENCAP:
err = seg6_do_srh_encap(skb, tinfo->srh);
break;
}
if (err)
return err;
ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
skb_set_transport_header(skb, sizeof(struct ipv6hdr));
skb_set_inner_protocol(skb, skb->protocol);
return 0;
}
int seg6_input(struct sk_buff *skb)
{
int err;
err = seg6_do_srh(skb);
if (unlikely(err)) {
kfree_skb(skb);
return err;
}
skb_dst_drop(skb);
ip6_route_input(skb);
return dst_input(skb);
}
int seg6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
{
struct dst_entry *orig_dst = skb_dst(skb);
struct dst_entry *dst = NULL;
struct seg6_lwt *slwt;
int err = -EINVAL;
err = seg6_do_srh(skb);
if (unlikely(err))
goto drop;
slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate);
#ifdef CONFIG_DST_CACHE
preempt_disable();
dst = dst_cache_get(&slwt->cache);
preempt_enable();
#endif
if (unlikely(!dst)) {
struct ipv6hdr *hdr = ipv6_hdr(skb);
struct flowi6 fl6;
fl6.daddr = hdr->daddr;
fl6.saddr = hdr->saddr;
fl6.flowlabel = ip6_flowinfo(hdr);
fl6.flowi6_mark = skb->mark;
fl6.flowi6_proto = hdr->nexthdr;
dst = ip6_route_output(net, NULL, &fl6);
if (dst->error) {
err = dst->error;
dst_release(dst);
goto drop;
}
#ifdef CONFIG_DST_CACHE
preempt_disable();
dst_cache_set_ip6(&slwt->cache, dst, &fl6.saddr);
preempt_enable();
#endif
}
skb_dst_drop(skb);
skb_dst_set(skb, dst);
return dst_output(net, sk, skb);
drop:
kfree_skb(skb);
return err;
}
static int seg6_build_state(struct net_device *dev, struct nlattr *nla,
unsigned int family, const void *cfg,
struct lwtunnel_state **ts)
{
struct nlattr *tb[SEG6_IPTUNNEL_MAX + 1];
struct seg6_iptunnel_encap *tuninfo;
struct lwtunnel_state *newts;
int tuninfo_len, min_size;
struct seg6_lwt *slwt;
int err;
err = nla_parse_nested(tb, SEG6_IPTUNNEL_MAX, nla,
seg6_iptunnel_policy);
if (err < 0)
return err;
if (!tb[SEG6_IPTUNNEL_SRH])
return -EINVAL;
tuninfo = nla_data(tb[SEG6_IPTUNNEL_SRH]);
tuninfo_len = nla_len(tb[SEG6_IPTUNNEL_SRH]);
/* tuninfo must contain at least the iptunnel encap structure,
* the SRH and one segment
*/
min_size = sizeof(*tuninfo) + sizeof(struct ipv6_sr_hdr) +
sizeof(struct in6_addr);
if (tuninfo_len < min_size)
return -EINVAL;
switch (tuninfo->mode) {
#ifdef CONFIG_IPV6_SEG6_INLINE
case SEG6_IPTUN_MODE_INLINE:
break;
#endif
case SEG6_IPTUN_MODE_ENCAP:
break;
default:
return -EINVAL;
}
/* verify that SRH is consistent */
if (!seg6_validate_srh(tuninfo->srh, tuninfo_len - sizeof(*tuninfo)))
return -EINVAL;
newts = lwtunnel_state_alloc(tuninfo_len + sizeof(*slwt));
if (!newts)
return -ENOMEM;
slwt = seg6_lwt_lwtunnel(newts);
#ifdef CONFIG_DST_CACHE
err = dst_cache_init(&slwt->cache, GFP_KERNEL);
if (err) {
kfree(newts);
return err;
}
#endif
memcpy(&slwt->tuninfo, tuninfo, tuninfo_len);
newts->type = LWTUNNEL_ENCAP_SEG6;
newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT |
LWTUNNEL_STATE_INPUT_REDIRECT;
newts->headroom = seg6_lwt_headroom(tuninfo);
*ts = newts;
return 0;
}
#ifdef CONFIG_DST_CACHE
static void seg6_destroy_state(struct lwtunnel_state *lwt)
{
dst_cache_destroy(&seg6_lwt_lwtunnel(lwt)->cache);
}
#endif
static int seg6_fill_encap_info(struct sk_buff *skb,
struct lwtunnel_state *lwtstate)
{
struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate);
if (nla_put_srh(skb, SEG6_IPTUNNEL_SRH, tuninfo))
return -EMSGSIZE;
return 0;
}
static int seg6_encap_nlsize(struct lwtunnel_state *lwtstate)
{
struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate);
return nla_total_size(SEG6_IPTUN_ENCAP_SIZE(tuninfo));
}
static int seg6_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
{
struct seg6_iptunnel_encap *a_hdr = seg6_encap_lwtunnel(a);
struct seg6_iptunnel_encap *b_hdr = seg6_encap_lwtunnel(b);
int len = SEG6_IPTUN_ENCAP_SIZE(a_hdr);
if (len != SEG6_IPTUN_ENCAP_SIZE(b_hdr))
return 1;
return memcmp(a_hdr, b_hdr, len);
}
static const struct lwtunnel_encap_ops seg6_iptun_ops = {
.build_state = seg6_build_state,
#ifdef CONFIG_DST_CACHE
.destroy_state = seg6_destroy_state,
#endif
.output = seg6_output,
.input = seg6_input,
.fill_encap = seg6_fill_encap_info,
.get_encap_size = seg6_encap_nlsize,
.cmp_encap = seg6_encap_cmp,
};
int __init seg6_iptunnel_init(void)
{
return lwtunnel_encap_add_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6);
}
void seg6_iptunnel_exit(void)
{
lwtunnel_encap_del_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6);
}