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64b87639c9
When we do "cat /proc/net/nf_conntrack", and meanwhile resize the conntrack
hash table via /sys/module/nf_conntrack/parameters/hashsize, race will
happen, because reader can observe a newly allocated hash but the old size
(or vice versa). So oops will happen like follows：
BUG: unable to handle kernel NULL pointer dereference at 0000000000000017
IP: [<ffffffffa0418e21>] seq_print_acct+0x11/0x50 [nf_conntrack]
Call Trace:
[<ffffffffa0412f4e>] ? ct_seq_show+0x14e/0x340 [nf_conntrack]
[<ffffffff81261a1c>] seq_read+0x2cc/0x390
[<ffffffff812a8d62>] proc_reg_read+0x42/0x70
[<ffffffff8123bee7>] __vfs_read+0x37/0x130
[<ffffffff81347980>] ? security_file_permission+0xa0/0xc0
[<ffffffff8123cf75>] vfs_read+0x95/0x140
[<ffffffff8123e475>] SyS_read+0x55/0xc0
[<ffffffff817c2572>] entry_SYSCALL_64_fastpath+0x1a/0xa4
It is very easy to reproduce this kernel crash.
1. open one shell and input the following cmds:
while : ; do
echo $RANDOM > /sys/module/nf_conntrack/parameters/hashsize
done
2. open more shells and input the following cmds:
while : ; do
cat /proc/net/nf_conntrack
done
3. just wait a monent, oops will happen soon.
The solution in this patch is based on Florian's Commit 5e3c61f981
("netfilter: conntrack: fix lookup race during hash resize"). And
add a wrapper function nf_conntrack_get_ht to get hash and hsize
suggested by Florian Westphal.
Signed-off-by: Liping Zhang <liping.zhang@spreadtrum.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
92 lines
3 KiB
C
92 lines
3 KiB
C
/*
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* This header is used to share core functionality between the
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* standalone connection tracking module, and the compatibility layer's use
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* of connection tracking.
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*
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* 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
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* - generalize L3 protocol dependent part.
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*
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* Derived from include/linux/netfiter_ipv4/ip_conntrack_core.h
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*/
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#ifndef _NF_CONNTRACK_CORE_H
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#define _NF_CONNTRACK_CORE_H
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#include <linux/netfilter.h>
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#include <net/netfilter/nf_conntrack_l3proto.h>
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#include <net/netfilter/nf_conntrack_l4proto.h>
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#include <net/netfilter/nf_conntrack_ecache.h>
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/* This header is used to share core functionality between the
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standalone connection tracking module, and the compatibility layer's use
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of connection tracking. */
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unsigned int nf_conntrack_in(struct net *net, u_int8_t pf, unsigned int hooknum,
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struct sk_buff *skb);
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int nf_conntrack_init_net(struct net *net);
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void nf_conntrack_cleanup_net(struct net *net);
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void nf_conntrack_cleanup_net_list(struct list_head *net_exit_list);
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int nf_conntrack_proto_pernet_init(struct net *net);
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void nf_conntrack_proto_pernet_fini(struct net *net);
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int nf_conntrack_proto_init(void);
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void nf_conntrack_proto_fini(void);
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int nf_conntrack_init_start(void);
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void nf_conntrack_cleanup_start(void);
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void nf_conntrack_init_end(void);
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void nf_conntrack_cleanup_end(void);
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bool nf_ct_get_tuple(const struct sk_buff *skb, unsigned int nhoff,
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unsigned int dataoff, u_int16_t l3num, u_int8_t protonum,
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struct net *net,
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struct nf_conntrack_tuple *tuple,
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const struct nf_conntrack_l3proto *l3proto,
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const struct nf_conntrack_l4proto *l4proto);
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bool nf_ct_invert_tuple(struct nf_conntrack_tuple *inverse,
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const struct nf_conntrack_tuple *orig,
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const struct nf_conntrack_l3proto *l3proto,
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const struct nf_conntrack_l4proto *l4proto);
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void nf_conntrack_get_ht(struct hlist_nulls_head **hash, unsigned int *hsize);
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/* Find a connection corresponding to a tuple. */
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struct nf_conntrack_tuple_hash *
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nf_conntrack_find_get(struct net *net,
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const struct nf_conntrack_zone *zone,
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const struct nf_conntrack_tuple *tuple);
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int __nf_conntrack_confirm(struct sk_buff *skb);
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/* Confirm a connection: returns NF_DROP if packet must be dropped. */
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static inline int nf_conntrack_confirm(struct sk_buff *skb)
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{
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struct nf_conn *ct = (struct nf_conn *)skb->nfct;
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int ret = NF_ACCEPT;
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if (ct && !nf_ct_is_untracked(ct)) {
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if (!nf_ct_is_confirmed(ct))
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ret = __nf_conntrack_confirm(skb);
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if (likely(ret == NF_ACCEPT))
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nf_ct_deliver_cached_events(ct);
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}
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return ret;
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}
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void
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print_tuple(struct seq_file *s, const struct nf_conntrack_tuple *tuple,
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const struct nf_conntrack_l3proto *l3proto,
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const struct nf_conntrack_l4proto *proto);
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#define CONNTRACK_LOCKS 1024
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extern struct hlist_nulls_head *nf_conntrack_hash;
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extern spinlock_t nf_conntrack_locks[CONNTRACK_LOCKS];
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void nf_conntrack_lock(spinlock_t *lock);
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extern spinlock_t nf_conntrack_expect_lock;
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#endif /* _NF_CONNTRACK_CORE_H */
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