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In tcp_ctloutput(), don't hold the inpcb lock over sooptcopyin(), rather,

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drop the lock and then re-acquire it, revalidating TCP connection state
assumptions when we do so.  This avoids a potential lock order reversal
(and potential deadlock, although none have been reported) due to the
inpcb lock being held over a page fault.

MFC after:	1 week
PR:		102752
Reviewed by:	bz
Reported by:	Václav Haisman <v dot haisman at sh dot cvut dot cz>
This commit is contained in:
Robert Watson 2008-01-18 12:19:50 +00:00
parent b4064df455
commit 1e8f5ffa35
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=175438
1 changed files with 55 additions and 25 deletions
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80
sys/netinet/tcp_usrreq.c
View file

@ -1232,15 +1232,20 @@ tcp_fill_info(struct tcpcb *tp, struct tcp_info *ti)
}
/*
* The new sockopt interface makes it possible for us to block in the
* copyin/out step (if we take a page fault). Taking a page fault at
* splnet() is probably a Bad Thing. (Since sockets and pcbs both now
* use TSM, there probably isn't any need for this function to run at
* splnet() any more. This needs more examination.)
*
* XXXRW: The locking here is wrong; we may take a page fault while holding
* the inpcb lock.
* tcp_ctloutput() must drop the inpcb lock before performing copyin on
* socket option arguments. When it re-acquires the lock after the copy, it
* has to revalidate that the connection is still valid for the socket
* option.
*/
#define INP_LOCK_RECHECK(inp) do { \
INP_LOCK(inp); \
if (inp->inp_vflag & (INP_TIMEWAIT | INP_DROPPED)) { \
INP_UNLOCK(inp); \
return (ECONNRESET); \
} \
tp = intotcpcb(inp); \
} while(0)
int
tcp_ctloutput(struct socket *so, struct sockopt *sopt)
{
@ -1254,44 +1259,52 @@ tcp_ctloutput(struct socket *so, struct sockopt *sopt)
KASSERT(inp != NULL, ("tcp_ctloutput: inp == NULL"));
INP_LOCK(inp);
if (sopt->sopt_level != IPPROTO_TCP) {
INP_UNLOCK(inp);
#ifdef INET6
if (INP_CHECK_SOCKAF(so, AF_INET6))
if (INP_CHECK_SOCKAF(so, AF_INET6)) {
INP_UNLOCK(inp);
error = ip6_ctloutput(so, sopt);
else
} else {
#endif /* INET6 */
error = ip_ctloutput(so, sopt);
INP_UNLOCK(inp);
error = ip_ctloutput(so, sopt);
#ifdef INET6
}
#endif
return (error);
}
if (inp->inp_vflag & (INP_TIMEWAIT | INP_DROPPED)) {
error = ECONNRESET;
goto out;
INP_UNLOCK(inp);
return (ECONNRESET);
}
tp = intotcpcb(inp);
switch (sopt->sopt_dir) {
case SOPT_SET:
switch (sopt->sopt_name) {
#ifdef TCP_SIGNATURE
case TCP_MD5SIG:
INP_UNLOCK(inp);
error = sooptcopyin(sopt, &optval, sizeof optval,
sizeof optval);
sizeof optval);
if (error)
break;
return (error);
INP_LOCK_RECHECK(inp);
if (optval > 0)
tp->t_flags |= TF_SIGNATURE;
else
tp->t_flags &= ~TF_SIGNATURE;
INP_UNLOCK(inp);
break;
#endif /* TCP_SIGNATURE */
case TCP_NODELAY:
case TCP_NOOPT:
INP_UNLOCK(inp);
error = sooptcopyin(sopt, &optval, sizeof optval,
sizeof optval);
sizeof optval);
if (error)
break;
return (error);
INP_LOCK_RECHECK(inp);
switch (sopt->sopt_name) {
case TCP_NODELAY:
opt = TF_NODELAY;
@ -1308,83 +1321,100 @@ tcp_ctloutput(struct socket *so, struct sockopt *sopt)
tp->t_flags |= opt;
else
tp->t_flags &= ~opt;
INP_UNLOCK(inp);
break;
case TCP_NOPUSH:
INP_UNLOCK(inp);
error = sooptcopyin(sopt, &optval, sizeof optval,
sizeof optval);
sizeof optval);
if (error)
break;
return (error);
INP_LOCK_RECHECK(inp);
if (optval)
tp->t_flags |= TF_NOPUSH;
else {
tp->t_flags &= ~TF_NOPUSH;
error = tcp_output(tp);
}
INP_UNLOCK(inp);
break;
case TCP_MAXSEG:
INP_UNLOCK(inp);
error = sooptcopyin(sopt, &optval, sizeof optval,
sizeof optval);
sizeof optval);
if (error)
break;
return (error);
INP_LOCK_RECHECK(inp);
if (optval > 0 && optval <= tp->t_maxseg &&
optval + 40 >= tcp_minmss)
tp->t_maxseg = optval;
else
error = EINVAL;
INP_UNLOCK(inp);
break;
case TCP_INFO:
INP_UNLOCK(inp);
error = EINVAL;
break;
default:
INP_UNLOCK(inp);
error = ENOPROTOOPT;
break;
}
break;
case SOPT_GET:
tp = intotcpcb(inp);
switch (sopt->sopt_name) {
#ifdef TCP_SIGNATURE
case TCP_MD5SIG:
optval = (tp->t_flags & TF_SIGNATURE) ? 1 : 0;
INP_UNLOCK(inp);
error = sooptcopyout(sopt, &optval, sizeof optval);
break;
#endif
case TCP_NODELAY:
optval = tp->t_flags & TF_NODELAY;
INP_UNLOCK(inp);
error = sooptcopyout(sopt, &optval, sizeof optval);
break;
case TCP_MAXSEG:
optval = tp->t_maxseg;
INP_UNLOCK(inp);
error = sooptcopyout(sopt, &optval, sizeof optval);
break;
case TCP_NOOPT:
optval = tp->t_flags & TF_NOOPT;
INP_UNLOCK(inp);
error = sooptcopyout(sopt, &optval, sizeof optval);
break;
case TCP_NOPUSH:
optval = tp->t_flags & TF_NOPUSH;
INP_UNLOCK(inp);
error = sooptcopyout(sopt, &optval, sizeof optval);
break;
case TCP_INFO:
tcp_fill_info(tp, &ti);
INP_UNLOCK(inp);
error = sooptcopyout(sopt, &ti, sizeof ti);
break;
default:
INP_UNLOCK(inp);
error = ENOPROTOOPT;
break;
}
break;
}
out:
INP_UNLOCK(inp);
return (error);
}
#undef INP_LOCK_RECHECK
/*
* tcp_sendspace and tcp_recvspace are the default send and receive window