Date: Wed, 24 Jan 2001 09:55:04 -0800 From: Alfred Perlstein <bright@wintelcom.net> To: John Baldwin <jhb@FreeBSD.org> Cc: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/alpha/osf1 osf1_misc.c osf1_signal.c Message-ID: <20010124095504.X26076@fw.wintelcom.net> In-Reply-To: <200101241027.f0OARBH07561@freefall.freebsd.org>; from jhb@FreeBSD.org on Wed, Jan 24, 2001 at 02:27:11AM -0800 References: <200101241027.f0OARBH07561@freefall.freebsd.org>
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* John Baldwin <jhb@FreeBSD.org> [010124 02:28] wrote:
> jhb 2001/01/24 02:27:11 PST
>
> Modified files:
> sys/alpha/osf1 osf1_misc.c osf1_signal.c
> Log:
> Proc locking.
I thought you said you would stop locking read only structures?
When I say "read-only" I mean from the context of other threads,
it's ok if a process changes its own p_cred, and no one should
be changing it out from under it.
If someone else is fiddling with another proc'd p_cred it
just needs to make sure that the process can't exit before
it's done.
uid = SCARG(uap, uid);
+ PROC_LOCK(p);
pc = p->p_cred;
if ((error = suser(p)) != 0 &&
- uid != pc->p_ruid && uid != pc->p_svuid)
+ uid != pc->p_ruid && uid != pc->p_svuid) {
+ PROC_UNLOCK(p);
return (error);
+ }
if (error == 0) {
if (uid != pc->p_ruid) {
+ PROC_UNLOCK(p);
change_ruid(p, uid);
setsugid(p);
+ PROC_LOCK(p);
}
if (pc->p_svuid != uid) {
+ PROC_UNLOCK(p);
pc->p_svuid = uid;
setsugid(p);
+ PROC_LOCK(p);
}
}
if (pc->pc_ucred->cr_uid != uid) {
+ PROC_UNLOCK(p);
change_euid(p, uid);
setsugid(p);
- }
+ } else
+ PROC_UNLOCK(p);
return (0);
}
pc = p->p_cred;
p->p_cred is read only, it is not shared between processes and
should never have a refcount > 1, the refcount is actually bogus
except in BSD/os where it is incorrectly assumed to be so.
We (currently) don't have this problem.
--
-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]
"I have the heart of a child; I keep it in a jar on my desk."
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