55432d2b54
commit 5faa5df1fa (inetpeer: Invalidate the inetpeer tree along with
the routing cache) added a race :
Before freeing an inetpeer, we must respect a RCU grace period, and make
sure no user will attempt to increase refcnt.
inetpeer_invalidate_tree() waits for a RCU grace period before inserting
inetpeer tree into gc_list and waking the worker. At that time, no
concurrent lookup can find a inetpeer in this tree.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
129 lines
3.1 KiB
C
129 lines
3.1 KiB
C
/*
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* INETPEER - A storage for permanent information about peers
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*
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* Authors: Andrey V. Savochkin <saw@msu.ru>
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*/
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#ifndef _NET_INETPEER_H
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#define _NET_INETPEER_H
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#include <linux/types.h>
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#include <linux/init.h>
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#include <linux/jiffies.h>
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#include <linux/spinlock.h>
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#include <linux/rtnetlink.h>
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#include <net/ipv6.h>
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#include <linux/atomic.h>
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struct inetpeer_addr_base {
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union {
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__be32 a4;
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__be32 a6[4];
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};
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};
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struct inetpeer_addr {
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struct inetpeer_addr_base addr;
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__u16 family;
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};
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struct inet_peer {
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/* group together avl_left,avl_right,v4daddr to speedup lookups */
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struct inet_peer __rcu *avl_left, *avl_right;
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struct inetpeer_addr daddr;
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__u32 avl_height;
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u32 metrics[RTAX_MAX];
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u32 rate_tokens; /* rate limiting for ICMP */
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unsigned long rate_last;
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unsigned long pmtu_expires;
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u32 pmtu_orig;
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u32 pmtu_learned;
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struct inetpeer_addr_base redirect_learned;
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union {
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struct list_head gc_list;
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struct rcu_head gc_rcu;
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};
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/*
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* Once inet_peer is queued for deletion (refcnt == -1), following fields
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* are not available: rid, ip_id_count, tcp_ts, tcp_ts_stamp
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* We can share memory with rcu_head to help keep inet_peer small.
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*/
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union {
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struct {
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atomic_t rid; /* Frag reception counter */
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atomic_t ip_id_count; /* IP ID for the next packet */
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__u32 tcp_ts;
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__u32 tcp_ts_stamp;
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};
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struct rcu_head rcu;
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struct inet_peer *gc_next;
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};
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/* following fields might be frequently dirtied */
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__u32 dtime; /* the time of last use of not referenced entries */
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atomic_t refcnt;
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};
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void inet_initpeers(void) __init;
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#define INETPEER_METRICS_NEW (~(u32) 0)
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static inline bool inet_metrics_new(const struct inet_peer *p)
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{
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return p->metrics[RTAX_LOCK-1] == INETPEER_METRICS_NEW;
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}
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/* can be called with or without local BH being disabled */
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struct inet_peer *inet_getpeer(const struct inetpeer_addr *daddr, int create);
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static inline struct inet_peer *inet_getpeer_v4(__be32 v4daddr, int create)
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{
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struct inetpeer_addr daddr;
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daddr.addr.a4 = v4daddr;
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daddr.family = AF_INET;
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return inet_getpeer(&daddr, create);
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}
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static inline struct inet_peer *inet_getpeer_v6(const struct in6_addr *v6daddr, int create)
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{
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struct inetpeer_addr daddr;
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*(struct in6_addr *)daddr.addr.a6 = *v6daddr;
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daddr.family = AF_INET6;
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return inet_getpeer(&daddr, create);
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}
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/* can be called from BH context or outside */
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extern void inet_putpeer(struct inet_peer *p);
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extern bool inet_peer_xrlim_allow(struct inet_peer *peer, int timeout);
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extern void inetpeer_invalidate_tree(int family);
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/*
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* temporary check to make sure we dont access rid, ip_id_count, tcp_ts,
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* tcp_ts_stamp if no refcount is taken on inet_peer
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*/
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static inline void inet_peer_refcheck(const struct inet_peer *p)
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{
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WARN_ON_ONCE(atomic_read(&p->refcnt) <= 0);
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}
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/* can be called with or without local BH being disabled */
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static inline int inet_getid(struct inet_peer *p, int more)
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{
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int old, new;
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more++;
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inet_peer_refcheck(p);
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do {
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old = atomic_read(&p->ip_id_count);
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new = old + more;
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if (!new)
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new = 1;
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} while (atomic_cmpxchg(&p->ip_id_count, old, new) != old);
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return new;
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}
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#endif /* _NET_INETPEER_H */
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