From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <4d70224fbe94a5bc6c67b78276a473cb@isd.dp.ua>
To: 9fans@9fans.net
From: yaroslav <yarikos@gmail.com>
Date: Wed, 27 Nov 2013 12:00:33 +0200
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Subject: [9fans] u9fs(4) misuses Fcall.afid in its p9any authentication
	module
Topicbox-Message-UUID: 8c29bb08-ead8-11e9-9d60-3106f5b1d025

U9fs(4) misuses Fcall.afid in its p9any authentication module.

The afid field of Fcall structure is only valid with Tauth or Tattach.
Tread, Twrite, Tclunk should use rx->fid instead.  It's been lucky so
far to get the job done because rx->afid survives from previous
Tauth/Tattach.  The issue pops up when several authentications happen
concurrently.

Test case:
	u9fs = 'host with u9fs on tcp!*!564'
	9fs $u9fs; for(i in 1 2 3 4 5 6 7 8){ 9fs $u9fs & }; wait
Should:
	no errors
Should not:
	mount failed: authentication failed

<patch/diff u9fs-afid
/sys/src/cmd/unix/u9fs/authp9any.c
	authp9any.c.orig:369,375 - /n/sources/patch/u9fs-afid/authp9any.c:369,378
	  		fprint(2, "p9anyattach: afid %d state %d\n", rx->afid, sp->state);
	  	if (sp->state == Established && strcmp(rx->uname, sp->uname) == 0
	  		&& strcmp(rx->aname, sp->aname) == 0)
	+ 	{
	+ 		rx->uname = sp->t.suid;		/* will be valid until afid is clunked */
	  		return nil;
	+ 	}
	  	return "authentication failed";
	  }

	authp9any.c.orig:392,398 - /n/sources/patch/u9fs-afid/authp9any.c:395,401
	  	char *ep;

	  	Fid *f;
	- 	f = oldauthfid(rx->afid, (void **)&sp, &ep);
	+ 	f = oldauthfid(rx->fid, (void **)&sp, &ep);
	  	if (f == nil)
	  		return ep;
	  	if (chatty9p)
	authp9any.c.orig:437,443 - /n/sources/patch/u9fs-afid/authp9any.c:440,446

	  	Fid *f;

	- 	f = oldauthfid(rx->afid, (void **)&sp, &ep);
	+ 	f = oldauthfid(rx->fid, (void **)&sp, &ep);
	  	if (f == nil)
	  		return ep;
	  	if (chatty9p)
	authp9any.c.orig:515,521 - /n/sources/patch/u9fs-afid/authp9any.c:518,524
	  	AuthSession *sp;
	  	char *ep;

	- 	f = oldauthfid(rx->afid, (void **)&sp, &ep);
	+ 	f = oldauthfid(rx->fid, (void **)&sp, &ep);
	  	if (f == nil)
	  		return ep;
	  	if (chatty9p)