2
0
mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-23 12:43:55 +08:00
linux-next/include/net/af_unix.h
Eric Dumazet 60bc851ae5 af_unix: fix a fatal race with bit fields
Using bit fields is dangerous on ppc64/sparc64, as the compiler [1]
uses 64bit instructions to manipulate them.
If the 64bit word includes any atomic_t or spinlock_t, we can lose
critical concurrent changes.

This is happening in af_unix, where unix_sk(sk)->gc_candidate/
gc_maybe_cycle/lock share the same 64bit word.

This leads to fatal deadlock, as one/several cpus spin forever
on a spinlock that will never be available again.

A safer way would be to use a long to store flags.
This way we are sure compiler/arch wont do bad things.

As we own unix_gc_lock spinlock when clearing or setting bits,
we can use the non atomic __set_bit()/__clear_bit().

recursion_level can share the same 64bit location with the spinlock,
as it is set only with this spinlock held.

[1] bug fixed in gcc-4.8.0 :
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52080

Reported-by: Ambrose Feinstein <ambrose@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-05-01 15:13:49 -04:00

81 lines
2.1 KiB
C

#ifndef __LINUX_NET_AFUNIX_H
#define __LINUX_NET_AFUNIX_H
#include <linux/socket.h>
#include <linux/un.h>
#include <linux/mutex.h>
#include <net/sock.h>
extern void unix_inflight(struct file *fp);
extern void unix_notinflight(struct file *fp);
extern void unix_gc(void);
extern void wait_for_unix_gc(void);
extern struct sock *unix_get_socket(struct file *filp);
extern struct sock *unix_peer_get(struct sock *);
#define UNIX_HASH_SIZE 256
#define UNIX_HASH_BITS 8
extern unsigned int unix_tot_inflight;
extern spinlock_t unix_table_lock;
extern struct hlist_head unix_socket_table[2 * UNIX_HASH_SIZE];
struct unix_address {
atomic_t refcnt;
int len;
unsigned int hash;
struct sockaddr_un name[0];
};
struct unix_skb_parms {
struct pid *pid; /* Skb credentials */
kuid_t uid;
kgid_t gid;
struct scm_fp_list *fp; /* Passed files */
#ifdef CONFIG_SECURITY_NETWORK
u32 secid; /* Security ID */
#endif
};
#define UNIXCB(skb) (*(struct unix_skb_parms *)&((skb)->cb))
#define UNIXSID(skb) (&UNIXCB((skb)).secid)
#define unix_state_lock(s) spin_lock(&unix_sk(s)->lock)
#define unix_state_unlock(s) spin_unlock(&unix_sk(s)->lock)
#define unix_state_lock_nested(s) \
spin_lock_nested(&unix_sk(s)->lock, \
SINGLE_DEPTH_NESTING)
/* The AF_UNIX socket */
struct unix_sock {
/* WARNING: sk has to be the first member */
struct sock sk;
struct unix_address *addr;
struct path path;
struct mutex readlock;
struct sock *peer;
struct list_head link;
atomic_long_t inflight;
spinlock_t lock;
unsigned char recursion_level;
unsigned long gc_flags;
#define UNIX_GC_CANDIDATE 0
#define UNIX_GC_MAYBE_CYCLE 1
struct socket_wq peer_wq;
};
#define unix_sk(__sk) ((struct unix_sock *)__sk)
#define peer_wait peer_wq.wait
long unix_inq_len(struct sock *sk);
long unix_outq_len(struct sock *sk);
#ifdef CONFIG_SYSCTL
extern int unix_sysctl_register(struct net *net);
extern void unix_sysctl_unregister(struct net *net);
#else
static inline int unix_sysctl_register(struct net *net) { return 0; }
static inline void unix_sysctl_unregister(struct net *net) {}
#endif
#endif