o Merge contents of struct pcred into struct ucred. Specifically, add the

  real uid, saved uid, real gid, and saved gid to ucred, as well as the
  pcred->pc_uidinfo, which was associated with the real uid, only rename
  it to cr_ruidinfo so as not to conflict with cr_uidinfo, which
  corresponds to the effective uid.
o Remove p_cred from struct proc; add p_ucred to struct proc, replacing
  original macro that pointed.
  p->p_ucred to p->p_cred->pc_ucred.
o Universally update code so that it makes use of ucred instead of pcred,
  p->p_ucred instead of p->p_pcred, cr_ruidinfo instead of p_uidinfo,
  cr_{r,sv}{u,g}id instead of p_*, etc.
o Remove pcred0 and its initialization from init_main.c; initialize
  cr_ruidinfo there.
o Restruction many credential modification chunks to always crdup while
  we figure out locking and optimizations; generally speaking, this
  means moving to a structure like this:
        newcred = crdup(oldcred);
        ...
        p->p_ucred = newcred;
        crfree(oldcred);
  It's not race-free, but better than nothing.  There are also races
  in sys_process.c, all inter-process authorization, fork, exec, and
  exit.
o Remove sigio->sio_ruid since sigio->sio_ucred now contains the ruid;
  remove comments indicating that the old arrangement was a problem.
o Restructure exec1() a little to use newcred/oldcred arrangement, and
  use improved uid management primitives.
o Clean up exit1() so as to do less work in credential cleanup due to
  pcred removal.
o Clean up fork1() so as to do less work in credential cleanup and
  allocation.
o Clean up ktrcanset() to take into account changes, and move to using
  suser_xxx() instead of performing a direct uid==0 comparision.
o Improve commenting in various kern_prot.c credential modification
  calls to better document current behavior.  In a couple of places,
  current behavior is a little questionable and we need to check
  POSIX.1 to make sure it's "right".  More commenting work still
  remains to be done.
o Update credential management calls, such as crfree(), to take into
  account new ruidinfo reference.
o Modify or add the following uid and gid helper routines:
      change_euid()
      change_egid()
      change_ruid()
      change_rgid()
      change_svuid()
      change_svgid()
  In each case, the call now acts on a credential not a process, and as
  such no longer requires more complicated process locking/etc.  They
  now assume the caller will do any necessary allocation of an
  exclusive credential reference.  Each is commented to document its
  reference requirements.
o CANSIGIO() is simplified to require only credentials, not processes
  and pcreds.
o Remove lots of (p_pcred==NULL) checks.
o Add an XXX to authorization code in nfs_lock.c, since it's
  questionable, and needs to be considered carefully.
o Simplify posix4 authorization code to require only credentials, not
  processes and pcreds.  Note that this authorization, as well as
  CANSIGIO(), needs to be updated to use the p_cansignal() and
  p_cansched() centralized authorization routines, as they currently
  do not take into account some desirable restrictions that are handled
  by the centralized routines, as well as being inconsistent with other
  similar authorization instances.
o Update libkvm to take these changes into account.

Obtained from:	TrustedBSD Project
Reviewed by:	green, bde, jhb, freebsd-arch, freebsd-audit

33 files changed, 484 insertions, 368 deletions

diff --git a/sys/alpha/osf1/osf1_misc.c b/sys/alpha/osf1/osf1_misc.c
index 707e640..7d9a213 100644
--- a/sys/alpha/osf1/osf1_misc.c
+++ b/sys/alpha/osf1/osf1_misc.c
@@ -1054,29 +1054,32 @@ osf1_setuid(p, uap)
 {
 	int error;
 	uid_t uid;
-	register struct pcred *pc;
+	struct ucred *newcred, oldcred;
 
 	uid = SCARG(uap, uid);
-	pc = p->p_cred;
+	oldcred = p->p_ucred;
 
 	if ((error = suser(p)) != 0 &&
-	    uid != pc->p_ruid && uid != pc->p_svuid)
+	    uid != oldcred->cr_ruid && uid != oldcred->cr_svuid)
 		return (error);
 
+	newcred = crdup(oldcred);
 	if (error == 0) {
-		if (uid != pc->p_ruid) {
-			change_ruid(p, uid);
+		if (uid != oldcred->cr_ruid) {
+			change_ruid(newcred, uid);
 			setsugid(p);
 		}
-		if (pc->p_svuid != uid) {
-			pc->p_svuid = uid;
+		if (oldcred->cr_svuid != uid) {
+			change_svuid(newcred, uid);
 			setsugid(p);
 		}
 	}
-	if (pc->pc_ucred->cr_uid != uid) {
-		change_euid(p, uid);
+	if (newcred->cr_uid != uid) {
+		change_euid(newcred, uid);
 		setsugid(p);
 	}
+	p->p_ucred = newcred;
+	crfree(oldcred);
 	return (0);
 }
 
@@ -1095,22 +1098,32 @@ osf1_setgid(p, uap)
 {
 	int error;
 	gid_t gid;
-	register struct pcred *pc;
+	struct ucred *newcred, *oldcred;
 
 	gid = SCARG(uap, gid);
-	pc = p->p_cred;
+	oldcred = p->p_ucred;
 
 	if (((error = suser(p)) != 0 ) &&
-		gid != pc->p_rgid && gid != pc->p_svgid)
+		gid != oldcred->cr_rgid && gid != oldcred->cr_svgid)
 		return (error);
 
-	pc->pc_ucred = crcopy(pc->pc_ucred);
-	pc->pc_ucred->cr_gid = gid;
+	newcred = crdup(oldcred);
 	if (error == 0) {
-		pc->p_rgid = gid;
-		pc->p_svgid = gid;
+		if (gid != oldcred->cr_rgid) {
+			change_rgid(newcred, gid);
+			setsugid(p);
+		}
+		if (oldcred->cr_svgid != gid) {
+			change_svgid(newcred, gid);
+			setsugid(p);
+		}
+	}
+	if (newcred->cr_groups[0] != gid) {
+		change_egid(newcred, gid);
+		setsugid(p);
 	}
-	setsugid(p);
+	p->p_ucred = newcred;
+	crfree(oldcred);
 	return (0);
 }
 
diff --git a/sys/compat/linprocfs/linprocfs.c b/sys/compat/linprocfs/linprocfs.c
index 6a356fb..04858f7 100644
--- a/sys/compat/linprocfs/linprocfs.c
+++ b/sys/compat/linprocfs/linprocfs.c
@@ -478,14 +478,14 @@ linprocfs_doprocstatus(curp, p, pfs, uio)
 	PROC_LOCK(p);
 	sbuf_printf(&sb, "PPid:\t%d\n",		p->p_pptr ?
 						p->p_pptr->p_pid : 0);
-	sbuf_printf(&sb, "Uid:\t%d %d %d %d\n", p->p_cred->p_ruid,
+	sbuf_printf(&sb, "Uid:\t%d %d %d %d\n", p->p_ucred->cr_ruid,
 			                        p->p_ucred->cr_uid,
-			                        p->p_cred->p_svuid,
+			                        p->p_ucred->cr_svuid,
 			                        /* FreeBSD doesn't have fsuid */
 				                p->p_ucred->cr_uid);
-	sbuf_printf(&sb, "Gid:\t%d %d %d %d\n", p->p_cred->p_rgid,
+	sbuf_printf(&sb, "Gid:\t%d %d %d %d\n", p->p_ucred->cr_rgid,
 			                        p->p_ucred->cr_gid,
-			                        p->p_cred->p_svgid,
+			                        p->p_ucred->cr_svgid,
 			                        /* FreeBSD doesn't have fsgid */
 				                p->p_ucred->cr_gid);
 	sbuf_cat(&sb, "Groups:\t");
@@ -577,7 +577,7 @@ linprocfs_doexelink(curp, p, pfs, uio)
 	char *freepath = NULL;
 
 	p = PFIND(pfs->pfs_pid);
-	if (p == NULL || p->p_cred == NULL || p->p_ucred == NULL) {
+	if (p == NULL || p->p_ucred == NULL) {
 		if (p != NULL)
 			PROC_UNLOCK(p);
 		printf("doexelink: pid %d disappeared\n", pfs->pfs_pid);
diff --git a/sys/compat/linprocfs/linprocfs_misc.c b/sys/compat/linprocfs/linprocfs_misc.c
index 6a356fb..04858f7 100644
--- a/sys/compat/linprocfs/linprocfs_misc.c
+++ b/sys/compat/linprocfs/linprocfs_misc.c
@@ -478,14 +478,14 @@ linprocfs_doprocstatus(curp, p, pfs, uio)
 	PROC_LOCK(p);
 	sbuf_printf(&sb, "PPid:\t%d\n",		p->p_pptr ?
 						p->p_pptr->p_pid : 0);
-	sbuf_printf(&sb, "Uid:\t%d %d %d %d\n", p->p_cred->p_ruid,
+	sbuf_printf(&sb, "Uid:\t%d %d %d %d\n", p->p_ucred->cr_ruid,
 			                        p->p_ucred->cr_uid,
-			                        p->p_cred->p_svuid,
+			                        p->p_ucred->cr_svuid,
 			                        /* FreeBSD doesn't have fsuid */
 				                p->p_ucred->cr_uid);
-	sbuf_printf(&sb, "Gid:\t%d %d %d %d\n", p->p_cred->p_rgid,
+	sbuf_printf(&sb, "Gid:\t%d %d %d %d\n", p->p_ucred->cr_rgid,
 			                        p->p_ucred->cr_gid,
-			                        p->p_cred->p_svgid,
+			                        p->p_ucred->cr_svgid,
 			                        /* FreeBSD doesn't have fsgid */
 				                p->p_ucred->cr_gid);
 	sbuf_cat(&sb, "Groups:\t");
@@ -577,7 +577,7 @@ linprocfs_doexelink(curp, p, pfs, uio)
 	char *freepath = NULL;
 
 	p = PFIND(pfs->pfs_pid);
-	if (p == NULL || p->p_cred == NULL || p->p_ucred == NULL) {
+	if (p == NULL || p->p_ucred == NULL) {
 		if (p != NULL)
 			PROC_UNLOCK(p);
 		printf("doexelink: pid %d disappeared\n", pfs->pfs_pid);
diff --git a/sys/compat/linprocfs/linprocfs_vnops.c b/sys/compat/linprocfs/linprocfs_vnops.c
index 2bb824e..08a5023 100644
--- a/sys/compat/linprocfs/linprocfs_vnops.c
+++ b/sys/compat/linprocfs/linprocfs_vnops.c
@@ -433,7 +433,7 @@ linprocfs_getattr(ap)
 		procp = PFIND(pfs->pfs_pid);
 		if (procp == NULL)
 			return (ENOENT);
-		if (procp->p_cred == NULL || procp->p_ucred == NULL) {
+		if (procp->p_ucred == NULL) {
 			PROC_UNLOCK(procp);
 			return (ENOENT);
 		}
diff --git a/sys/compat/linux/linux_misc.c b/sys/compat/linux/linux_misc.c
index 2c7c9b5..64200b1 100644
--- a/sys/compat/linux/linux_misc.c
+++ b/sys/compat/linux/linux_misc.c
@@ -958,13 +958,13 @@ linux_setgroups(p, uap)
 	struct proc *p;
 	struct linux_setgroups_args *uap;
 {
-	struct pcred *pc;
+	struct ucred *newcred, *oldcred;
 	linux_gid_t linux_gidset[NGROUPS];
 	gid_t *bsd_gidset;
 	int ngrp, error;
 
-	pc = p->p_cred;
 	ngrp = uap->gidsetsize;
+	oldcred = p->p_ucred;
 
 	/*
 	 * cr_groups[0] holds egid. Setting the whole set from
@@ -972,22 +972,22 @@ linux_setgroups(p, uap)
 	 * Keep cr_groups[0] unchanged to prevent that.
 	 */
 
-	if ((error = suser_xxx(NULL, p, PRISON_ROOT)) != 0)
+	if ((error = suser_xxx(oldcred, NULL, PRISON_ROOT)) != 0)
 		return (error);
 
 	if (ngrp >= NGROUPS)
 		return (EINVAL);
 
-	pc->pc_ucred = crcopy(pc->pc_ucred);
+	newcred = crdup(oldcred);
 	if (ngrp > 0) {
 		error = copyin((caddr_t)uap->gidset, (caddr_t)linux_gidset,
 			       ngrp * sizeof(linux_gid_t));
 		if (error)
 			return (error);
 
-		pc->pc_ucred->cr_ngroups = ngrp + 1;
+		newcred->cr_ngroups = ngrp + 1;
 
-		bsd_gidset = pc->pc_ucred->cr_groups;
+		bsd_gidset = newcred->cr_groups;
 		ngrp--;
 		while (ngrp >= 0) {
 			bsd_gidset[ngrp + 1] = linux_gidset[ngrp];
@@ -995,9 +995,11 @@ linux_setgroups(p, uap)
 		}
 	}
 	else
-		pc->pc_ucred->cr_ngroups = 1;
+		newcred->cr_ngroups = 1;
 
 	setsugid(p);
+	p->p_ucred = newcred;
+	crfree(oldcred);
 	return (0);
 }
 
@@ -1006,14 +1008,14 @@ linux_getgroups(p, uap)
 	struct proc *p;
 	struct linux_getgroups_args *uap;
 {
-	struct pcred *pc;
+	struct ucred *cred;
 	linux_gid_t linux_gidset[NGROUPS];
 	gid_t *bsd_gidset;
 	int bsd_gidsetsz, ngrp, error;
 
-	pc = p->p_cred;
-	bsd_gidset = pc->pc_ucred->cr_groups;
-	bsd_gidsetsz = pc->pc_ucred->cr_ngroups - 1;
+	cred = p->p_ucred;
+	bsd_gidset = cred->cr_groups;
+	bsd_gidsetsz = cred->cr_ngroups - 1;
 
 	/*
 	 * cr_groups[0] holds egid. Returning the whole set
diff --git a/sys/compat/svr4/svr4_misc.c b/sys/compat/svr4/svr4_misc.c
index 1baed66..a92e8a4 100644
--- a/sys/compat/svr4/svr4_misc.c
+++ b/sys/compat/svr4/svr4_misc.c
@@ -1283,7 +1283,7 @@ loop:
 			/*
 			 * Decrement the count of procs running with this uid.
 			 */
-			(void)chgproccnt(q->p_cred->p_uidinfo, -1, 0);
+			(void)chgproccnt(q->p_ucred->cr_ruidinfo, -1, 0);
 
 			/*
 			 * Release reference to text vnode.
@@ -1294,13 +1294,8 @@ loop:
 			/*
 			 * Free up credentials.
 			 */
-			PROC_LOCK(q);
-			if (--q->p_cred->p_refcnt == 0) {
-				crfree(q->p_ucred);
-				uifree(q->p_cred->p_uidinfo);
-				FREE(q->p_cred, M_SUBPROC);
-				q->p_cred = NULL;
-			}
+			crfree(q->p_ucred);
+			q->p_ucred = NULL;
 
 			/*
 			 * Remove unused arguments
diff --git a/sys/compat/svr4/svr4_sysvec.c b/sys/compat/svr4/svr4_sysvec.c
index 912cd2a..9137e0c 100644
--- a/sys/compat/svr4/svr4_sysvec.c
+++ b/sys/compat/svr4/svr4_sysvec.c
@@ -213,10 +213,10 @@ svr4_fixup(register_t **stack_base, struct image_params *imgp)
 	AUXARGS_ENTRY(pos, AT_FLAGS, args->flags);
 	AUXARGS_ENTRY(pos, AT_ENTRY, args->entry);
 	AUXARGS_ENTRY(pos, AT_BASE, args->base);
-	AUXARGS_ENTRY(pos, AT_UID, imgp->proc->p_cred->p_ruid);
-	AUXARGS_ENTRY(pos, AT_EUID, imgp->proc->p_cred->p_svuid);
-	AUXARGS_ENTRY(pos, AT_GID, imgp->proc->p_cred->p_rgid);
-	AUXARGS_ENTRY(pos, AT_EGID, imgp->proc->p_cred->p_svgid);
+	AUXARGS_ENTRY(pos, AT_UID, imgp->proc->p_ucred->cr_ruid);
+	AUXARGS_ENTRY(pos, AT_EUID, imgp->proc->p_ucred->cr_svuid);
+	AUXARGS_ENTRY(pos, AT_GID, imgp->proc->p_ucred->cr_rgid);
+	AUXARGS_ENTRY(pos, AT_EGID, imgp->proc->p_ucred->cr_svgid);
 	AUXARGS_ENTRY(pos, AT_NULL, 0);
 	
 	free(imgp->auxargs, M_TEMP);      
diff --git a/sys/ddb/db_ps.c b/sys/ddb/db_ps.c
index bccda5a..cbedb1e 100644
--- a/sys/ddb/db_ps.c
+++ b/sys/ddb/db_ps.c
@@ -95,7 +95,7 @@ db_ps(dummy1, dummy2, dummy3, dummy4)
 
 		db_printf("%5d %8p %8p %4d %5d %5d %06x  %d",
 		    p->p_pid, (volatile void *)p, (void *)p->p_addr,
-		    p->p_cred ? p->p_cred->p_ruid : 0, pp->p_pid,
+		    p->p_ucred ? p->p_ucred->cr_ruid : 0, pp->p_pid,
 		    p->p_pgrp ? p->p_pgrp->pg_id : 0, p->p_flag, p->p_stat);
 		if (p->p_wchan) {
 			db_printf("  %6s %8p", p->p_wmesg, (void *)p->p_wchan);
diff --git a/sys/fs/procfs/procfs_status.c b/sys/fs/procfs/procfs_status.c
index 9620be5..0f57e49 100644
--- a/sys/fs/procfs/procfs_status.c
+++ b/sys/fs/procfs/procfs_status.c
@@ -153,11 +153,11 @@ procfs_dostatus(curp, p, pfs, uio)
 
 	ps += snprintf(ps, psbuf + sizeof(psbuf) - ps, " %lu %lu %lu", 
 		(u_long)cr->cr_uid,
-		(u_long)p->p_cred->p_ruid,
-		(u_long)p->p_cred->p_rgid);
+		(u_long)cr->cr_ruid,
+		(u_long)cr->cr_rgid);
 	DOCHECK();
 
-	/* egid (p->p_cred->p_svgid) is equal to cr_ngroups[0] 
+	/* egid (cr->cr_svgid) is equal to cr_ngroups[0] 
 	   see also getegid(2) in /sys/kern/kern_prot.c */
 
 	for (i = 0; i < cr->cr_ngroups; i++) {
diff --git a/sys/fs/procfs/procfs_vnops.c b/sys/fs/procfs/procfs_vnops.c
index a054eb9..4ca89ac 100644
--- a/sys/fs/procfs/procfs_vnops.c
+++ b/sys/fs/procfs/procfs_vnops.c
@@ -403,7 +403,7 @@ procfs_getattr(ap)
 		procp = PFIND(pfs->pfs_pid);
 		if (procp == NULL)
 			return (ENOENT);
-		if (procp->p_cred == NULL || procp->p_ucred == NULL) {
+		if (procp->p_ucred == NULL) {
 			PROC_UNLOCK(procp);
 			return (ENOENT);
 		}
@@ -941,8 +941,7 @@ procfs_readlink(ap)
 	 */
 	case Pfile:
 		procp = PFIND(pfs->pfs_pid);
-		if (procp == NULL || procp->p_cred == NULL ||
-		    procp->p_ucred == NULL) {
+		if (procp == NULL || procp->p_ucred == NULL) {
 			if (procp != NULL)
 				PROC_UNLOCK(procp);
 			printf("procfs_readlink: pid %d disappeared\n",
diff --git a/sys/i386/linux/linux_sysvec.c b/sys/i386/linux/linux_sysvec.c
index 0734ba4..de82774 100644
--- a/sys/i386/linux/linux_sysvec.c
+++ b/sys/i386/linux/linux_sysvec.c
@@ -187,10 +187,10 @@ elf_linux_fixup(register_t **stack_base, struct image_params *imgp)
 	AUXARGS_ENTRY(pos, AT_ENTRY, args->entry);
 	AUXARGS_ENTRY(pos, AT_BASE, args->base);
 	PROC_LOCK(imgp->proc);
-	AUXARGS_ENTRY(pos, AT_UID, imgp->proc->p_cred->p_ruid);
-	AUXARGS_ENTRY(pos, AT_EUID, imgp->proc->p_cred->p_svuid);
-	AUXARGS_ENTRY(pos, AT_GID, imgp->proc->p_cred->p_rgid);
-	AUXARGS_ENTRY(pos, AT_EGID, imgp->proc->p_cred->p_svgid);
+	AUXARGS_ENTRY(pos, AT_UID, imgp->proc->p_ucred->cr_ruid);
+	AUXARGS_ENTRY(pos, AT_EUID, imgp->proc->p_ucred->cr_svuid);
+	AUXARGS_ENTRY(pos, AT_GID, imgp->proc->p_ucred->cr_rgid);
+	AUXARGS_ENTRY(pos, AT_EGID, imgp->proc->p_ucred->cr_svgid);
 	PROC_UNLOCK(imgp->proc);
 	AUXARGS_ENTRY(pos, AT_NULL, 0);
 	
diff --git a/sys/kern/init_main.c b/sys/kern/init_main.c
index 5624720..9698983 100644
--- a/sys/kern/init_main.c
+++ b/sys/kern/init_main.c
@@ -85,7 +85,6 @@ void mi_startup(void);				/* Should be elsewhere */
 static struct session session0;
 static struct pgrp pgrp0;
 struct	proc proc0;
-static struct pcred cred0;
 static struct procsig procsig0;
 static struct filedesc0 filedesc0;
 static struct plimit limit0;
@@ -333,12 +332,10 @@ proc0_init(void *dummy __unused)
 	callout_init(&p->p_slpcallout, 1);
 
 	/* Create credentials. */
-	cred0.p_refcnt = 1;
-	cred0.p_uidinfo = uifind(0);
-	p->p_cred = &cred0;
 	p->p_ucred = crget();
 	p->p_ucred->cr_ngroups = 1;	/* group 0 */
 	p->p_ucred->cr_uidinfo = uifind(0);
+	p->p_ucred->cr_ruidinfo = uifind(0);
 	p->p_ucred->cr_prison = NULL;	/* Don't jail it. */
 
 	/* Create procsig. */
@@ -394,7 +391,7 @@ proc0_init(void *dummy __unused)
 	/*
 	 * Charge root for one process.
 	 */
-	(void)chgproccnt(cred0.p_uidinfo, 1, 0);
+	(void)chgproccnt(p->p_ucred->cr_ruidinfo, 1, 0);
 }
 SYSINIT(p0init, SI_SUB_INTRINSIC, SI_ORDER_FIRST, proc0_init, NULL)
 
diff --git a/sys/kern/kern_acct.c b/sys/kern/kern_acct.c
index 7562e31..98f2495 100644
--- a/sys/kern/kern_acct.c
+++ b/sys/kern/kern_acct.c
@@ -222,8 +222,8 @@ acct_process(p)
 	acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0);
 
 	/* (6) The UID and GID of the process */
-	acct.ac_uid = p->p_cred->p_ruid;
-	acct.ac_gid = p->p_cred->p_rgid;
+	acct.ac_uid = p->p_ucred->cr_ruid;
+	acct.ac_gid = p->p_ucred->cr_rgid;
 
 	/* (7) The terminal from which the process was started */
 	if ((p->p_flag & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp)
diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index f89e413..b2cc930 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -525,8 +525,6 @@ fsetown(pgid, sigiop)
 	sigio->sio_pgid = pgid;
 	crhold(curproc->p_ucred);
 	sigio->sio_ucred = curproc->p_ucred;
-	/* It would be convenient if p_ruid was in ucred. */
-	sigio->sio_ruid = curproc->p_cred->p_ruid;
 	sigio->sio_myref = sigiop;
 	s = splhigh();
 	*sigiop = sigio;
diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c
index abb08fc..e3ae485 100644
--- a/sys/kern/kern_exec.c
+++ b/sys/kern/kern_exec.c
@@ -104,6 +104,7 @@ execve(p, uap)
 	register struct execve_args *uap;
 {
 	struct nameidata nd, *ndp;
+	struct ucred *newcred, *oldcred;
 	register_t *stack_base;
 	int error, len, i;
 	struct image_params image_params, *imgp;
@@ -274,13 +275,24 @@ interpret:
 	}
 
 	/*
+	 * XXX: Note, the whole execve() is incredibly racey right now
+	 * with regards to debugging and privilege/credential management.
+	 * In particular, it's possible to race during exec() to attach
+	 * debugging to a process that will gain privilege.
+	 *
+	 * This MUST be fixed prior to any release.
+	 */
+
+	/*
 	 * Implement image setuid/setgid.
 	 *
 	 * Don't honor setuid/setgid if the filesystem prohibits it or if
 	 * the process is being traced.
 	 */
-	if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) ||
-	     ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) &&
+	oldcred = p->p_ucred;
+	newcred = NULL;
+	if ((((attr.va_mode & VSUID) && oldcred->cr_uid != attr.va_uid) ||
+	     ((attr.va_mode & VSGID) && oldcred->cr_gid != attr.va_gid)) &&
 	    (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 &&
 	    (p->p_flag & P_TRACED) == 0) {
 		PROC_UNLOCK(p);
@@ -288,7 +300,7 @@ interpret:
 		 * Turn off syscall tracing for set-id programs, except for
 		 * root.
 		 */
-		if (p->p_tracep && suser(p)) {
+		if (p->p_tracep && suser_xxx(oldcred, NULL, PRISON_ROOT)) {
 			p->p_traceflag = 0;
 			vrele(p->p_tracep);
 			p->p_tracep = NULL;
@@ -296,25 +308,49 @@ interpret:
 		/*
 		 * Set the new credentials.
 		 */
-		p->p_ucred = crcopy(p->p_ucred);
+		newcred = crdup(oldcred);
 		if (attr.va_mode & VSUID)
-			change_euid(p, attr.va_uid);
+			change_euid(newcred, attr.va_uid);
 		if (attr.va_mode & VSGID)
-			p->p_ucred->cr_gid = attr.va_gid;
+			change_egid(newcred, attr.va_gid);
 		setsugid(p);
 		setugidsafety(p);
 	} else {
-		if (p->p_ucred->cr_uid == p->p_cred->p_ruid &&
-		    p->p_ucred->cr_gid == p->p_cred->p_rgid)
+		if (oldcred->cr_uid == oldcred->cr_ruid &&
+		    oldcred->cr_gid == oldcred->cr_rgid)
 			p->p_flag &= ~P_SUGID;
 		PROC_UNLOCK(p);
 	}
 
 	/*
 	 * Implement correct POSIX saved-id behavior.
-	 */
-	p->p_cred->p_svuid = p->p_ucred->cr_uid;
-	p->p_cred->p_svgid = p->p_ucred->cr_gid;
+	 *
+	 * XXX: It's not clear that the existing behavior is
+	 * POSIX-compliant.  A number of sourses indicate that the saved
+	 * uid/gid should only be updated if the new ruid is not equal to
+	 * the old ruid, or the new euid is not equal to the old euid and
+	 * the new euid is not equal to the old ruid.  The FreeBSD code
+	 * always updates the saved uid/gid.  Also, this code uses the new
+	 * (replaced) euid and egid as the source, which may or may not be
+	 * the right ones to use.
+	 */
+	if (oldcred->cr_svuid != oldcred->cr_uid ||
+	    oldcred->cr_svgid != oldcred->cr_gid) {
+		/*
+		 * Avoid allocating a newcred if we don't have one yet and
+		 * the saved uid/gid update would be a noop.
+		 */
+		if (newcred == NULL)
+			newcred = crdup(oldcred);
+		change_svuid(newcred, newcred->cr_uid);
+		change_svgid(newcred, newcred->cr_gid);
+	}
+	if (newcred != NULL) {
+		PROC_LOCK(p);
+		p->p_ucred = newcred;
+		PROC_UNLOCK(p);
+		crfree(oldcred);
+	}
 
 	/*
 	 * Store the vp for use in procfs
diff --git a/sys/kern/kern_exit.c b/sys/kern/kern_exit.c
index 1af27d2..6454d11 100644
--- a/sys/kern/kern_exit.c
+++ b/sys/kern/kern_exit.c
@@ -516,7 +516,7 @@ loop:
 			/*
 			 * Decrement the count of procs running with this uid.
 			 */
-			(void)chgproccnt(p->p_cred->p_uidinfo, -1, 0);
+			(void)chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0);
 
 			/*
 			 * Release reference to text vnode
@@ -541,12 +541,8 @@ loop:
 			/*
 			 * Free up credentials.
 			 */
-			if (--p->p_cred->p_refcnt == 0) {
-				crfree(p->p_ucred);
-				uifree(p->p_cred->p_uidinfo);
-				FREE(p->p_cred, M_SUBPROC);
-				p->p_cred = NULL;
-			}
+			crfree(p->p_ucred);
+			p->p_ucred = NULL;
 
 			/*
 			 * Remove unused arguments
diff --git a/sys/kern/kern_fork.c b/sys/kern/kern_fork.c
index 62dcc06..6774f64 100644
--- a/sys/kern/kern_fork.c
+++ b/sys/kern/kern_fork.c
@@ -258,7 +258,7 @@ fork1(p1, flags, procp)
 	 * exceed the limit. The variable nprocs is the current number of
 	 * processes, maxproc is the limit.
 	 */
-	uid = p1->p_cred->p_ruid;
+	uid = p1->p_ucred->cr_ruid;
 	if ((nprocs >= maxproc - 1 && uid != 0) || nprocs >= maxproc) {
 		tablefull("proc");
 		return (EAGAIN);
@@ -273,7 +273,7 @@ fork1(p1, flags, procp)
 	 * Increment the count of procs running with this uid. Don't allow
 	 * a nonprivileged user to exceed their current limit.
 	 */
-	ok = chgproccnt(p1->p_cred->p_uidinfo, 1,
+	ok = chgproccnt(p1->p_ucred->cr_ruidinfo, 1,
 		(uid != 0) ? p1->p_rlimit[RLIMIT_NPROC].rlim_cur : 0);
 	if (!ok) {
 		/*
@@ -409,15 +409,9 @@ again:
 	 * We start off holding one spinlock after fork: sched_lock.
 	 */
 	p2->p_spinlocks = 1;
-	PROC_UNLOCK(p2);
-	MALLOC(p2->p_cred, struct pcred *, sizeof(struct pcred),
-	    M_SUBPROC, M_WAITOK);
-	PROC_LOCK(p2);
 	PROC_LOCK(p1);
-	bcopy(p1->p_cred, p2->p_cred, sizeof(*p2->p_cred));
-	p2->p_cred->p_refcnt = 1;
 	crhold(p1->p_ucred);
-	uihold(p1->p_cred->p_uidinfo);
+	p2->p_ucred = p1->p_ucred;
 
 	if (p2->p_args)
 		p2->p_args->ar_ref++;
diff --git a/sys/kern/kern_ktrace.c b/sys/kern/kern_ktrace.c
index ce972bd..15b51c8 100644
--- a/sys/kern/kern_ktrace.c
+++ b/sys/kern/kern_ktrace.c
@@ -531,17 +531,17 @@ static int
 ktrcanset(callp, targetp)
 	struct proc *callp, *targetp;
 {
-	register struct pcred *caller = callp->p_cred;
-	register struct pcred *target = targetp->p_cred;
+	struct ucred *callcr = callp->p_ucred;
+	struct ucred *targetcr = targetp->p_ucred;
 
-	if (prison_check(callp->p_ucred, targetp->p_ucred))
+	if (prison_check(callcr, targetcr))
 		return (0);
-	if ((caller->pc_ucred->cr_uid == target->p_ruid &&
-	     target->p_ruid == target->p_svuid &&
-	     caller->p_rgid == target->p_rgid &&	/* XXX */
-	     target->p_rgid == target->p_svgid &&
+	if ((callcr->cr_uid == targetcr->cr_ruid &&
+	     targetcr->cr_ruid == targetcr->cr_svuid &&
+	     callcr->cr_rgid == targetcr->cr_rgid &&	/* XXX */
+	     targetcr->cr_rgid == targetcr->cr_svgid &&
 	     (targetp->p_traceflag & KTRFAC_ROOT) == 0) ||
-	     caller->pc_ucred->cr_uid == 0)
+	     !suser_xxx(callcr, NULL, PRISON_ROOT))
 		return (1);
 
 	return (0);
diff --git a/sys/kern/kern_proc.c b/sys/kern/kern_proc.c
index d441144..f45ac26 100644
--- a/sys/kern/kern_proc.c
+++ b/sys/kern/kern_proc.c
@@ -424,15 +424,15 @@ fill_kinfo_proc(p, kp)
 	kp->ki_textvp = p->p_textvp;
 	kp->ki_fd = p->p_fd;
 	kp->ki_vmspace = p->p_vmspace;
-	if (p->p_cred) {
-		kp->ki_uid = p->p_cred->pc_ucred->cr_uid;
-		kp->ki_ruid = p->p_cred->p_ruid;
-		kp->ki_svuid = p->p_cred->p_svuid;
-		kp->ki_ngroups = p->p_cred->pc_ucred->cr_ngroups;
-		bcopy(p->p_cred->pc_ucred->cr_groups, kp->ki_groups,
+	if (p->p_ucred) {
+		kp->ki_uid = p->p_ucred->cr_uid;
+		kp->ki_ruid = p->p_ucred->cr_ruid;
+		kp->ki_svuid = p->p_ucred->cr_svuid;
+		kp->ki_ngroups = p->p_ucred->cr_ngroups;
+		bcopy(p->p_ucred->cr_groups, kp->ki_groups,
 		    NGROUPS * sizeof(gid_t));
-		kp->ki_rgid = p->p_cred->p_rgid;
-		kp->ki_svgid = p->p_cred->p_svgid;
+		kp->ki_rgid = p->p_ucred->cr_rgid;
+		kp->ki_svgid = p->p_ucred->cr_svgid;
 	}
 	if (p->p_procsig) {
 		kp->ki_sigignore = p->p_procsig->ps_sigignore;
@@ -653,7 +653,7 @@ sysctl_kern_proc(SYSCTL_HANDLER_ARGS)
 
 			case KERN_PROC_RUID:
 				if (p->p_ucred == NULL || 
-				    p->p_cred->p_ruid != (uid_t)name[0])
+				    p->p_ucred->cr_ruid != (uid_t)name[0])
 					continue;
 				break;
 			}
diff --git a/sys/kern/kern_prot.c b/sys/kern/kern_prot.c
index f0b4ff8..fcef6d0 100644
--- a/sys/kern/kern_prot.c
+++ b/sys/kern/kern_prot.c
@@ -210,7 +210,7 @@ getuid(p, uap)
 	struct getuid_args *uap;
 {
 
-	p->p_retval[0] = p->p_cred->p_ruid;
+	p->p_retval[0] = p->p_ucred->cr_ruid;
 #if defined(COMPAT_43) || defined(COMPAT_SUNOS)
 	p->p_retval[1] = p->p_ucred->cr_uid;
 #endif
@@ -253,7 +253,7 @@ getgid(p, uap)
 	struct getgid_args *uap;
 {
 
-	p->p_retval[0] = p->p_cred->p_rgid;
+	p->p_retval[0] = p->p_ucred->cr_rgid;
 #if defined(COMPAT_43) || defined(COMPAT_SUNOS)
 	p->p_retval[1] = p->p_ucred->cr_groups[0];
 #endif
@@ -293,18 +293,18 @@ getgroups(p, uap)
 	struct proc *p;
 	register struct	getgroups_args *uap;
 {
-	register struct pcred *pc = p->p_cred;
-	register u_int ngrp;
+	struct ucred *cred = p->p_ucred;
+	u_int ngrp;
 	int error;
 
 	if ((ngrp = uap->gidsetsize) == 0) {
-		p->p_retval[0] = pc->pc_ucred->cr_ngroups;
+		p->p_retval[0] = cred->cr_ngroups;
 		return (0);
 	}
-	if (ngrp < pc->pc_ucred->cr_ngroups)
+	if (ngrp < cred->cr_ngroups)
 		return (EINVAL);
-	ngrp = pc->pc_ucred->cr_ngroups;
-	if ((error = copyout((caddr_t)pc->pc_ucred->cr_groups,
+	ngrp = cred->cr_ngroups;
+	if ((error = copyout((caddr_t)cred->cr_groups,
 	    (caddr_t)uap->gidset, ngrp * sizeof(gid_t))))
 		return (error);
 	p->p_retval[0] = ngrp;
@@ -427,10 +427,12 @@ setuid(p, uap)
 	struct proc *p;
 	struct setuid_args *uap;
 {
-	register struct pcred *pc = p->p_cred;
-	register uid_t uid;
+	struct ucred *newcred, *oldcred;
+	uid_t uid;
 	int error;
 
+	uid = uap->uid;
+	oldcred = p->p_ucred;
 	/*
 	 * See if we have "permission" by POSIX 1003.1 rules.
 	 *
@@ -448,17 +450,17 @@ setuid(p, uap)
 	 *    change.  Determined by compile options.
 	 * 3: Change euid last. (after tests in #2 for "appropriate privs")
 	 */
-	uid = uap->uid;
-	if (uid != pc->p_ruid &&		/* allow setuid(getuid()) */
+	if (uid != oldcred->cr_ruid &&		/* allow setuid(getuid()) */
 #ifdef _POSIX_SAVED_IDS
-	    uid != pc->p_svuid &&		/* allow setuid(saved gid) */
+	    uid != oldcred->cr_svuid &&		/* allow setuid(saved gid) */
 #endif
 #ifdef POSIX_APPENDIX_B_4_2_2	/* Use BSD-compat clause from B.4.2.2 */
-	    uid != pc->pc_ucred->cr_uid &&	/* allow setuid(geteuid()) */
+	    uid != oldcred->cr_uid &&		/* allow setuid(geteuid()) */
 #endif
-	    (error = suser_xxx(0, p, PRISON_ROOT)))
+	    (error = suser_xxx(oldcred, NULL, PRISON_ROOT)))
 		return (error);
 
+	newcred = crdup(oldcred);
 #ifdef _POSIX_SAVED_IDS
 	/*
 	 * Do we have "appropriate privileges" (are we root or uid == euid)
@@ -466,16 +468,16 @@ setuid(p, uap)
 	 */
 	if (
 #ifdef POSIX_APPENDIX_B_4_2_2	/* Use the clause from B.4.2.2 */
-	    uid == pc->pc_ucred->cr_uid ||
+	    uid == oldcred->cr_uid ||
 #endif
-	    suser_xxx(0, p, PRISON_ROOT) == 0) /* we are using privs */
+	    suser_xxx(oldcred, NULL, PRISON_ROOT) == 0) /* we are using privs */
 #endif
 	{
 		/*
 		 * Set the real uid and transfer proc count to new user.
 		 */
-		if (uid != pc->p_ruid) {
-			change_ruid(p, uid);
+		if (uid != oldcred->cr_ruid) {
+			change_ruid(newcred, uid);
 			setsugid(p);
 		}
 		/*
@@ -485,8 +487,8 @@ setuid(p, uap)
 		 * the security of seteuid() depends on it.  B.4.2.2 says it
 		 * is important that we should do this.
 		 */
-		if (pc->p_svuid != uid) {
-			pc->p_svuid = uid;
+		if (uid != oldcred->cr_svuid) {
+			change_svuid(newcred, uid);
 			setsugid(p);
 		}
 	}
@@ -495,10 +497,12 @@ setuid(p, uap)
 	 * In all permitted cases, we are changing the euid.
 	 * Copy credentials so other references do not see our changes.
 	 */
-	if (pc->pc_ucred->cr_uid != uid) {
-		change_euid(p, uid);
+	if (uid != oldcred->cr_uid) {
+		change_euid(newcred, uid);
 		setsugid(p);
 	}
+	p->p_ucred = newcred;
+	crfree(oldcred);
 	return (0);
 }
 
@@ -513,23 +517,27 @@ seteuid(p, uap)
 	struct proc *p;
 	struct seteuid_args *uap;
 {
-	register struct pcred *pc = p->p_cred;
-	register uid_t euid;
+	struct ucred *newcred, *oldcred;
+	uid_t euid;
 	int error;
 
 	euid = uap->euid;
-	if (euid != pc->p_ruid &&		/* allow seteuid(getuid()) */
-	    euid != pc->p_svuid &&		/* allow seteuid(saved uid) */
-	    (error = suser_xxx(0, p, PRISON_ROOT)))
+	oldcred = p->p_ucred;
+	if (euid != oldcred->cr_ruid &&		/* allow seteuid(getuid()) */
+	    euid != oldcred->cr_svuid &&	/* allow seteuid(saved uid) */
+	    (error = suser_xxx(oldcred, NULL, PRISON_ROOT)))
 		return (error);
 	/*
 	 * Everything's okay, do it.  Copy credentials so other references do
 	 * not see our changes.
 	 */
-	if (pc->pc_ucred->cr_uid != euid) {
-		change_euid(p, euid);
+	newcred = crdup(oldcred);
+	if (oldcred->cr_uid != euid) {
+		change_euid(newcred, euid);
 		setsugid(p);
 	}
+	p->p_ucred = newcred;
+	crfree(oldcred);
 	return (0);
 }
 
@@ -544,10 +552,12 @@ setgid(p, uap)
 	struct proc *p;
 	struct setgid_args *uap;
 {
-	register struct pcred *pc = p->p_cred;
-	register gid_t gid;
+	struct ucred *newcred, *oldcred;
+	gid_t gid;
 	int error;
 
+	gid = uap->gid;
+	oldcred = p->p_ucred;
 	/*
 	 * See if we have "permission" by POSIX 1003.1 rules.
 	 *
@@ -559,17 +569,17 @@ setgid(p, uap)
 	 *
 	 * For notes on the logic here, see setuid() above.
 	 */
-	gid = uap->gid;
-	if (gid != pc->p_rgid &&		/* allow setgid(getgid()) */
+	if (gid != oldcred->cr_rgid &&		/* allow setgid(getgid()) */
 #ifdef _POSIX_SAVED_IDS
-	    gid != pc->p_svgid &&		/* allow setgid(saved gid) */
+	    gid != oldcred->cr_svgid &&		/* allow setgid(saved gid) */
 #endif
 #ifdef POSIX_APPENDIX_B_4_2_2	/* Use BSD-compat clause from B.4.2.2 */
-	    gid != pc->pc_ucred->cr_groups[0] && /* allow setgid(getegid()) */
+	    gid != oldcred->cr_groups[0] && /* allow setgid(getegid()) */
 #endif
-	    (error = suser_xxx(0, p, PRISON_ROOT)))
+	    (error = suser_xxx(oldcred, NULL, PRISON_ROOT)))
 		return (error);
 
+	newcred = crdup(oldcred);
 #ifdef _POSIX_SAVED_IDS
 	/*
 	 * Do we have "appropriate privileges" (are we root or gid == egid)
@@ -577,16 +587,16 @@ setgid(p, uap)
 	 */
 	if (
 #ifdef POSIX_APPENDIX_B_4_2_2	/* use the clause from B.4.2.2 */
-	    gid == pc->pc_ucred->cr_groups[0] ||
+	    gid == oldcred->cr_groups[0] ||
 #endif
-	    suser_xxx(0, p, PRISON_ROOT) == 0) /* we are using privs */
+	    suser_xxx(oldcred, NULL, PRISON_ROOT) == 0) /* we are using privs */
 #endif
 	{
 		/*
 		 * Set real gid
 		 */
-		if (pc->p_rgid != gid) {
-			pc->p_rgid = gid;
+		if (oldcred->cr_rgid != gid) {
+			change_rgid(newcred, gid);
 			setsugid(p);
 		}
 		/*
@@ -596,8 +606,8 @@ setgid(p, uap)
 		 * the security of setegid() depends on it.  B.4.2.2 says it
 		 * is important that we should do this.
 		 */
-		if (pc->p_svgid != gid) {
-			pc->p_svgid = gid;
+		if (oldcred->cr_svgid != gid) {
+			change_svgid(newcred, gid);
 			setsugid(p);
 		}
 	}
@@ -605,11 +615,12 @@ setgid(p, uap)
 	 * In all cases permitted cases, we are changing the egid.
 	 * Copy credentials so other references do not see our changes.
 	 */
-	if (pc->pc_ucred->cr_groups[0] != gid) {
-		pc->pc_ucred = crcopy(pc->pc_ucred);
-		pc->pc_ucred->cr_groups[0] = gid;
+	if (oldcred->cr_groups[0] != gid) {
+		change_egid(newcred, gid);
 		setsugid(p);
 	}
+	p->p_ucred = newcred;
+	crfree(oldcred);
 	return (0);
 }
 
@@ -624,20 +635,23 @@ setegid(p, uap)
 	struct proc *p;
 	struct setegid_args *uap;
 {
-	register struct pcred *pc = p->p_cred;
-	register gid_t egid;
+	struct ucred *newcred, *oldcred;
+	gid_t egid;
 	int error;
 
 	egid = uap->egid;
-	if (egid != pc->p_rgid &&		/* allow setegid(getgid()) */
-	    egid != pc->p_svgid &&		/* allow setegid(saved gid) */
-	    (error = suser_xxx(0, p, PRISON_ROOT)))
+	oldcred = p->p_ucred;
+	if (egid != oldcred->cr_rgid &&		/* allow setegid(getgid()) */
+	    egid != oldcred->cr_svgid &&	/* allow setegid(saved gid) */
+	    (error = suser_xxx(oldcred, NULL, PRISON_ROOT)))
 		return (error);
-	if (pc->pc_ucred->cr_groups[0] != egid) {
-		pc->pc_ucred = crcopy(pc->pc_ucred);
-		pc->pc_ucred->cr_groups[0] = egid;
+	newcred = crdup(oldcred);
+	if (oldcred->cr_groups[0] != egid) {
+		change_egid(newcred, egid);
 		setsugid(p);
 	}
+	p->p_ucred = newcred;
+	crfree(oldcred);
 	return (0);
 }
 
@@ -653,20 +667,21 @@ setgroups(p, uap)
 	struct proc *p;
 	struct setgroups_args *uap;
 {
-	register struct pcred *pc = p->p_cred;
-	register u_int ngrp;
+	struct ucred *newcred, *oldcred;
+	u_int ngrp;
 	int error;
 
-	if ((error = suser_xxx(0, p, PRISON_ROOT)))
-		return (error);
 	ngrp = uap->gidsetsize;
+	oldcred = p->p_ucred;
+	if ((error = suser_xxx(oldcred, NULL, PRISON_ROOT)))
+		return (error);
 	if (ngrp > NGROUPS)
 		return (EINVAL);
 	/*
 	 * XXX A little bit lazy here.  We could test if anything has
 	 * changed before crcopy() and setting P_SUGID.
 	 */
-	pc->pc_ucred = crcopy(pc->pc_ucred);
+	newcred = crdup(oldcred);
 	if (ngrp < 1) {
 		/*
 		 * setgroups(0, NULL) is a legitimate way of clearing the
@@ -674,14 +689,18 @@ setgroups(p, uap)
 		 * have the egid in the groups[0]).  We risk security holes
 		 * when running non-BSD software if we do not do the same.
 		 */
-		pc->pc_ucred->cr_ngroups = 1;
+		newcred->cr_ngroups = 1;
 	} else {
 		if ((error = copyin((caddr_t)uap->gidset,
-		    (caddr_t)pc->pc_ucred->cr_groups, ngrp * sizeof(gid_t))))
+		    (caddr_t)newcred->cr_groups, ngrp * sizeof(gid_t)))) {
+			crfree(newcred);
 			return (error);
-		pc->pc_ucred->cr_ngroups = ngrp;
+		}
+		newcred->cr_ngroups = ngrp;
 	}
 	setsugid(p);
+	p->p_ucred = newcred;
+	crfree(oldcred);
 	return (0);
 }
 
@@ -697,31 +716,35 @@ setreuid(p, uap)
 	register struct proc *p;
 	struct setreuid_args *uap;
 {
-	register struct pcred *pc = p->p_cred;
-	register uid_t ruid, euid;
+	struct ucred *newcred, *oldcred;
+	uid_t ruid, euid;
 	int error;
 
 	ruid = uap->ruid;
 	euid = uap->euid;
-	if (((ruid != (uid_t)-1 && ruid != pc->p_ruid && ruid != pc->p_svuid) ||
-	     (euid != (uid_t)-1 && euid != pc->pc_ucred->cr_uid &&
-	     euid != pc->p_ruid && euid != pc->p_svuid)) &&
-	    (error = suser_xxx(0, p, PRISON_ROOT)) != 0)
+	oldcred = p->p_ucred;
+	if (((ruid != (uid_t)-1 && ruid != oldcred->cr_ruid &&
+	      ruid != oldcred->cr_svuid) ||
+	     (euid != (uid_t)-1 && euid != oldcred->cr_uid &&
+	      euid != oldcred->cr_ruid && euid != oldcred->cr_svuid)) &&
+	    (error = suser_xxx(oldcred, NULL, PRISON_ROOT)) != 0)
 		return (error);
-
-	if (euid != (uid_t)-1 && pc->pc_ucred->cr_uid != euid) {
-		change_euid(p, euid);
+	newcred = crdup(oldcred);
+	if (euid != (uid_t)-1 && oldcred->cr_uid != euid) {
+		change_euid(newcred, euid);
 		setsugid(p);
 	}
-	if (ruid != (uid_t)-1 && pc->p_ruid != ruid) {
-		change_ruid(p, ruid);
+	if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) {
+		change_ruid(newcred, ruid);
 		setsugid(p);
 	}
-	if ((ruid != (uid_t)-1 || pc->pc_ucred->cr_uid != pc->p_ruid) &&
-	    pc->p_svuid != pc->pc_ucred->cr_uid) {
-		pc->p_svuid = pc->pc_ucred->cr_uid;
+	if ((ruid != (uid_t)-1 || newcred->cr_uid != newcred->cr_ruid) &&
+	    newcred->cr_svuid != newcred->cr_uid) {
+		change_svuid(newcred, newcred->cr_uid);
 		setsugid(p);
 	}
+	p->p_ucred = newcred;
+	crfree(oldcred);
 	return (0);
 }
 
@@ -737,30 +760,32 @@ setregid(p, uap)
 	register struct proc *p;
 	struct setregid_args *uap;
 {
-	register struct pcred *pc = p->p_cred;
-	register gid_t rgid, egid;
+	struct ucred *newcred, *oldcred;
+	gid_t rgid, egid;
 	int error;
 
 	rgid = uap->rgid;
 	egid = uap->egid;
-	if (((rgid != (gid_t)-1 && rgid != pc->p_rgid && rgid != pc->p_svgid) ||
-	     (egid != (gid_t)-1 && egid != pc->pc_ucred->cr_groups[0] &&
-	     egid != pc->p_rgid && egid != pc->p_svgid)) &&
-	    (error = suser_xxx(0, p, PRISON_ROOT)) != 0)
+	oldcred = p->p_ucred;
+	if (((rgid != (gid_t)-1 && rgid != oldcred->cr_rgid &&
+	    rgid != oldcred->cr_svgid) ||
+	     (egid != (gid_t)-1 && egid != oldcred->cr_groups[0] &&
+	     egid != oldcred->cr_rgid && egid != oldcred->cr_svgid)) &&
+	    (error = suser_xxx(oldcred, NULL, PRISON_ROOT)) != 0)
 		return (error);
 
-	if (egid != (gid_t)-1 && pc->pc_ucred->cr_groups[0] != egid) {
-		pc->pc_ucred = crcopy(pc->pc_ucred);
-		pc->pc_ucred->cr_groups[0] = egid;
+	newcred = crdup(oldcred);
+	if (egid != (gid_t)-1 && oldcred->cr_groups[0] != egid) {
+		change_egid(newcred, egid);
 		setsugid(p);
 	}
-	if (rgid != (gid_t)-1 && pc->p_rgid != rgid) {
-		pc->p_rgid = rgid;
+	if (rgid != (gid_t)-1 && oldcred->cr_rgid != rgid) {
+		change_rgid(newcred, rgid);
 		setsugid(p);
 	}
-	if ((rgid != (gid_t)-1 || pc->pc_ucred->cr_groups[0] != pc->p_rgid) &&
-	    pc->p_svgid != pc->pc_ucred->cr_groups[0]) {
-		pc->p_svgid = pc->pc_ucred->cr_groups[0];
+	if ((rgid != (gid_t)-1 || newcred->cr_groups[0] != newcred->cr_rgid) &&
+	    newcred->cr_svgid != newcred->cr_groups[0]) {
+		change_svgid(newcred, newcred->cr_groups[0]);
 		setsugid(p);
 	}
 	return (0);
@@ -784,33 +809,41 @@ setresuid(p, uap)
 	register struct proc *p;
 	struct setresuid_args *uap;
 {
-	register struct pcred *pc = p->p_cred;
-	register uid_t ruid, euid, suid;
+	struct ucred *newcred, *oldcred;
+	uid_t ruid, euid, suid;
 	int error;
 
 	ruid = uap->ruid;
 	euid = uap->euid;
 	suid = uap->suid;
-	if (((ruid != (uid_t)-1 && ruid != pc->p_ruid && ruid != pc->p_svuid &&
-	      ruid != pc->pc_ucred->cr_uid) ||
-	     (euid != (uid_t)-1 && euid != pc->p_ruid && euid != pc->p_svuid &&
-	      euid != pc->pc_ucred->cr_uid) ||
-	     (suid != (uid_t)-1 && suid != pc->p_ruid && suid != pc->p_svuid &&
-	      suid != pc->pc_ucred->cr_uid)) &&
-	    (error = suser_xxx(0, p, PRISON_ROOT)) != 0)
+	oldcred = p->p_ucred;
+	if (((ruid != (uid_t)-1 && ruid != oldcred->cr_ruid &&
+	     ruid != oldcred->cr_svuid &&
+	      ruid != oldcred->cr_uid) ||
+	     (euid != (uid_t)-1 && euid != oldcred->cr_ruid &&
+	    euid != oldcred->cr_svuid &&
+	      euid != oldcred->cr_uid) ||
+	     (suid != (uid_t)-1 && suid != oldcred->cr_ruid &&
+	    suid != oldcred->cr_svuid &&
+	      suid != oldcred->cr_uid)) &&
+	    (error = suser_xxx(oldcred, NULL, PRISON_ROOT)) != 0)
 		return (error);
-	if (euid != (uid_t)-1 && pc->pc_ucred->cr_uid != euid) {
-		change_euid(p, euid);
+
+	newcred = crdup(oldcred);
+	if (euid != (uid_t)-1 && oldcred->cr_uid != euid) {
+		change_euid(newcred, euid);
 		setsugid(p);
 	}
-	if (ruid != (uid_t)-1 && pc->p_ruid != ruid) {
-		change_ruid(p, ruid);
+	if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) {
+		change_ruid(newcred, ruid);
 		setsugid(p);
 	}
-	if (suid != (uid_t)-1 && pc->p_svuid != suid) {
-		pc->p_svuid = suid;
+	if (suid != (uid_t)-1 && oldcred->cr_svuid != suid) {
+		change_svuid(newcred, suid);
 		setsugid(p);
 	}
+	p->p_ucred = newcred;
+	crfree(oldcred);
 	return (0);
 }
 
@@ -832,35 +865,41 @@ setresgid(p, uap)
 	register struct proc *p;
 	struct setresgid_args *uap;
 {
-	register struct pcred *pc = p->p_cred;
-	register gid_t rgid, egid, sgid;
+	struct ucred *newcred, *oldcred;
+	gid_t rgid, egid, sgid;
 	int error;
 
 	rgid = uap->rgid;
 	egid = uap->egid;
 	sgid = uap->sgid;
-	if (((rgid != (gid_t)-1 && rgid != pc->p_rgid && rgid != pc->p_svgid &&
-	      rgid != pc->pc_ucred->cr_groups[0]) ||
-	     (egid != (gid_t)-1 && egid != pc->p_rgid && egid != pc->p_svgid &&
-	      egid != pc->pc_ucred->cr_groups[0]) ||
-	     (sgid != (gid_t)-1 && sgid != pc->p_rgid && sgid != pc->p_svgid &&
-	      sgid != pc->pc_ucred->cr_groups[0])) &&
-	    (error = suser_xxx(0, p, PRISON_ROOT)) != 0)
+	oldcred = p->p_ucred;
+	if (((rgid != (gid_t)-1 && rgid != oldcred->cr_rgid &&
+	      rgid != oldcred->cr_svgid &&
+	      rgid != oldcred->cr_groups[0]) ||
+	     (egid != (gid_t)-1 && egid != oldcred->cr_rgid &&
+	      egid != oldcred->cr_svgid &&
+	      egid != oldcred->cr_groups[0]) ||
+	     (sgid != (gid_t)-1 && sgid != oldcred->cr_rgid &&
+	      sgid != oldcred->cr_svgid &&
+	      sgid != oldcred->cr_groups[0])) &&
+	    (error = suser_xxx(oldcred, NULL, PRISON_ROOT)) != 0)
 		return (error);
 
-	if (egid != (gid_t)-1 && pc->pc_ucred->cr_groups[0] != egid) {
-		pc->pc_ucred = crcopy(pc->pc_ucred);
-		pc->pc_ucred->cr_groups[0] = egid;
+	newcred = crdup(oldcred);
+	if (egid != (gid_t)-1 && oldcred->cr_groups[0] != egid) {
+		change_egid(newcred, egid);
 		setsugid(p);
 	}
-	if (rgid != (gid_t)-1 && pc->p_rgid != rgid) {
-		pc->p_rgid = rgid;
+	if (rgid != (gid_t)-1 && oldcred->cr_rgid != rgid) {
+		change_rgid(newcred, rgid);
 		setsugid(p);
 	}
-	if (sgid != (gid_t)-1 && pc->p_svgid != sgid) {
-		pc->p_svgid = sgid;
+	if (sgid != (gid_t)-1 && oldcred->cr_svgid != sgid) {
+		change_svgid(newcred, sgid);
 		setsugid(p);
 	}
+	p->p_ucred = newcred;
+	crfree(oldcred);
 	return (0);
 }
 
@@ -877,18 +916,18 @@ getresuid(p, uap)
 	register struct proc *p;
 	struct getresuid_args *uap;
 {
-	struct pcred *pc = p->p_cred;
+	struct ucred *cred = p->p_ucred;
 	int error1 = 0, error2 = 0, error3 = 0;
 
 	if (uap->ruid)
-		error1 = copyout((caddr_t)&pc->p_ruid,
-		    (caddr_t)uap->ruid, sizeof(pc->p_ruid));
+		error1 = copyout((caddr_t)&cred->cr_ruid,
+		    (caddr_t)uap->ruid, sizeof(cred->cr_ruid));
 	if (uap->euid)
-		error2 = copyout((caddr_t)&pc->pc_ucred->cr_uid,
-		    (caddr_t)uap->euid, sizeof(pc->pc_ucred->cr_uid));
+		error2 = copyout((caddr_t)&cred->cr_uid,
+		    (caddr_t)uap->euid, sizeof(cred->cr_uid));
 	if (uap->suid)
-		error3 = copyout((caddr_t)&pc->p_svuid,
-		    (caddr_t)uap->suid, sizeof(pc->p_svuid));
+		error3 = copyout((caddr_t)&cred->cr_svuid,
+		    (caddr_t)uap->suid, sizeof(cred->cr_svuid));
 	return error1 ? error1 : (error2 ? error2 : error3);
 }
 
@@ -905,18 +944,18 @@ getresgid(p, uap)
 	register struct proc *p;
 	struct getresgid_args *uap;
 {
-	struct pcred *pc = p->p_cred;
+	struct ucred *cred = p->p_ucred;
 	int error1 = 0, error2 = 0, error3 = 0;
 
 	if (uap->rgid)
-		error1 = copyout((caddr_t)&pc->p_rgid,
-		    (caddr_t)uap->rgid, sizeof(pc->p_rgid));
+		error1 = copyout((caddr_t)&cred->cr_rgid,
+		    (caddr_t)uap->rgid, sizeof(cred->cr_rgid));
 	if (uap->egid)
-		error2 = copyout((caddr_t)&pc->pc_ucred->cr_groups[0],
-		    (caddr_t)uap->egid, sizeof(pc->pc_ucred->cr_groups[0]));
+		error2 = copyout((caddr_t)&cred->cr_groups[0],
+		    (caddr_t)uap->egid, sizeof(cred->cr_groups[0]));
 	if (uap->sgid)
-		error3 = copyout((caddr_t)&pc->p_svgid,
-		    (caddr_t)uap->sgid, sizeof(pc->p_svgid));
+		error3 = copyout((caddr_t)&cred->cr_svgid,
+		    (caddr_t)uap->sgid, sizeof(cred->cr_svgid));
 	return error1 ? error1 : (error2 ? error2 : error3);
 }
 
@@ -972,7 +1011,7 @@ __setugid(p, uap)
 int
 groupmember(gid, cred)
 	gid_t gid;
-	register struct ucred *cred;
+	struct ucred *cred;
 {
 	register gid_t *gp;
 	gid_t *egp;
@@ -1038,7 +1077,7 @@ u_cansee(struct ucred *u1, struct ucred *u2)
 
 	if ((error = prison_check(u1, u2)))
 		return (error);
-	if (!ps_showallprocs && u1->cr_uid != u2->cr_uid) {
+	if (!ps_showallprocs && u1->cr_ruid != u2->cr_ruid) {
 		if (suser_xxx(u1, NULL, PRISON_ROOT) != 0)
 			return (ESRCH);
 	}
@@ -1113,10 +1152,10 @@ p_cansignal(struct proc *p1, struct proc *p2, int signum)
 	 * Generally, the object credential's ruid or svuid must match the
 	 * subject credential's ruid or euid.
 	 */
-	if (p1->p_cred->p_ruid != p2->p_cred->p_ruid &&
-	    p1->p_cred->p_ruid != p2->p_cred->p_svuid &&
-	    p1->p_ucred->cr_uid != p2->p_cred->p_ruid &&
-	    p1->p_ucred->cr_uid != p2->p_cred->p_svuid) {
+	if (p1->p_ucred->cr_ruid != p2->p_ucred->cr_ruid &&
+	    p1->p_ucred->cr_ruid != p2->p_ucred->cr_svuid &&
+	    p1->p_ucred->cr_uid != p2->p_ucred->cr_ruid &&
+	    p1->p_ucred->cr_uid != p2->p_ucred->cr_svuid) {
 		/* Not permitted, try privilege. */
 		error = suser_xxx(NULL, p1, PRISON_ROOT);
 		if (error)
@@ -1140,9 +1179,9 @@ p_cansched(struct proc *p1, struct proc *p2, int *privused)
 	if ((error = prison_check(p1->p_ucred, p2->p_ucred)))
 		return (error);
 
-	if (p1->p_cred->p_ruid == p2->p_cred->p_ruid)
+	if (p1->p_ucred->cr_ruid == p2->p_ucred->cr_ruid)
 		return (0);
-	if (p1->p_ucred->cr_uid == p2->p_cred->p_ruid)
+	if (p1->p_ucred->cr_uid == p2->p_ucred->cr_ruid)
 		return (0);
 
 	if (!suser_xxx(0, p1, PRISON_ROOT)) {
@@ -1178,9 +1217,9 @@ p_candebug(struct proc *p1, struct proc *p2, int *privused)
 
 	/* not owned by you, has done setuid (unless you're root) */
 	/* add a CAP_SYS_PTRACE here? */
-	if (p1->p_cred->pc_ucred->cr_uid != p2->p_cred->pc_ucred->cr_uid ||
-	    p1->p_cred->pc_ucred->cr_uid != p2->p_cred->p_svuid ||
-	    p1->p_cred->pc_ucred->cr_uid != p2->p_cred->p_ruid ||
+	if (p1->p_ucred->cr_uid != p2->p_ucred->cr_uid ||
+	    p1->p_ucred->cr_uid != p2->p_ucred->cr_svuid ||
+	    p1->p_ucred->cr_uid != p2->p_ucred->cr_ruid ||
 	    p2->p_flag & P_SUGID) {
 		if ((error = suser_xxx(0, p1, PRISON_ROOT)))
 			return (error);
@@ -1308,6 +1347,7 @@ crdup(cr)
 	*newcr = *cr;
 	mtx_init(&newcr->cr_mtx, "ucred", MTX_DEF);
 	uihold(newcr->cr_uidinfo);
+	uihold(newcr->cr_ruidinfo);
 	if (jailed(newcr))
 		prison_hold(newcr->cr_prison);
 	newcr->cr_ref = 1;
@@ -1375,48 +1415,99 @@ setsugid(p)
 }
 
 /*
- * Helper function to change the effective uid of a process
+ * change_euid(): Change a process's effective uid.
+ * Side effects: newcred->cr_uid and newcred->cr_uidinfo will be modified.
+ * References: newcred must be an exclusive credential reference for the
+ *             duration of the call.
  */
 void
-change_euid(p, euid)
-	struct	proc *p;
-	uid_t	euid;
+change_euid(newcred, euid)
+	struct ucred *newcred;
+	uid_t euid;
 {
-	struct	pcred *pc;
-	struct	uidinfo *uip;
 
-	pc = p->p_cred;
-	/*
-	 * crcopy is essentially a NOP if ucred has a reference count
-	 * of 1, which is true if it has already been copied.
-	 */
-	pc->pc_ucred = crcopy(pc->pc_ucred);
-	uip = pc->pc_ucred->cr_uidinfo;
-	pc->pc_ucred->cr_uid = euid;
-	pc->pc_ucred->cr_uidinfo = uifind(euid);
-	uifree(uip);
+	newcred->cr_uid = euid;
+	uifree(newcred->cr_uidinfo);
+	newcred->cr_uidinfo = uifind(euid);
 }
 
 /*
- * Helper function to change the real uid of a process
- *
- * The per-uid process count for this process is transfered from
- * the old uid to the new uid.
+ * change_egid(): Change a process's effective gid.
+ * Side effects: newcred->cr_gid will be modified.
+ * References: newcred must be an exclusive credential reference for the
+ *             duration of the call.
  */
 void
-change_ruid(p, ruid)
-	struct	proc *p;
-	uid_t	ruid;
+change_egid(newcred, egid)
+	struct ucred *newcred;
+	gid_t egid;
+{
+
+	newcred->cr_groups[0] = egid;
+}
+
+/*
+ * change_ruid(): Change a process's real uid.
+ * Side effects: newcred->cr_ruid will be updated, newcred->cr_ruidinfo
+ *               will be updated, and the old and new cr_ruidinfo proc
+ *               counts will be updated.
+ * References: newcred must be an exclusive credential reference for the
+ *             duration of the call.
+ */
+void
+change_ruid(newcred, ruid)
+	struct ucred *newcred;
+	uid_t ruid;
+{
+
+	(void)chgproccnt(newcred->cr_ruidinfo, -1, 0);
+	newcred->cr_ruid = ruid;
+	uifree(newcred->cr_ruidinfo);
+	newcred->cr_ruidinfo = uifind(ruid);
+	(void)chgproccnt(newcred->cr_ruidinfo, 1, 0);
+}
+
+/*
+ * change_rgid(): Change a process's real gid.
+ * Side effects: newcred->cr_rgid will be updated.
+ * References: newcred must be an exclusive credential reference for the
+ *             duration of the call.
+ */
+void
+change_rgid(newcred, rgid)
+	struct ucred *newcred;
+	gid_t rgid;
 {
-	struct	pcred *pc;
-	struct	uidinfo *uip;
-
-	pc = p->p_cred;
-	(void)chgproccnt(pc->p_uidinfo, -1, 0);
-	uip = pc->p_uidinfo;
-	/* It is assumed that pcred is not shared between processes */
-	pc->p_ruid = ruid;
-	pc->p_uidinfo = uifind(ruid);
-	(void)chgproccnt(pc->p_uidinfo, 1, 0);
-	uifree(uip);
+
+	newcred->cr_rgid = rgid;
+}
+
+/*
+ * change_svuid(): Change a process's saved uid.
+ * Side effects: newcred->cr_svuid will be updated.
+ * References: newcred must be an exclusive credential reference for the
+ *             duration of the call.
+ */
+void
+change_svuid(newcred, svuid)
+	struct ucred *newcred;
+	uid_t svuid;
+{
+
+	newcred->cr_svuid = svuid;
+}
+
+/*
+ * change_svgid(): Change a process's saved gid.
+ * Side effects: newcred->cr_svgid will be updated.
+ * References: newcred must be an exclusive credential reference for the
+ *             duration of the call.
+ */
+void
+change_svgid(newcred, svgid)
+	struct ucred *newcred;
+	gid_t svgid;
+{
+
+	newcred->cr_svgid = svgid;
 }
diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
index 56837f4..ae68268 100644
--- a/sys/kern/kern_sig.c
+++ b/sys/kern/kern_sig.c
@@ -97,14 +97,14 @@ SYSCTL_INT(_kern, KERN_LOGSIGEXIT, logsigexit, CTLFLAG_RW,
     "Log processes quitting on abnormal signals to syslog(3)");
 
 /*
- * Policy -- Can real uid ruid with ucred uc send a signal to process q?
+ * Policy -- Can ucred cr1 send SIGIO to process cr2?
  */
-#define CANSIGIO(ruid, uc, q) \
-	((uc)->cr_uid == 0 || \
-	    (ruid) == (q)->p_cred->p_ruid || \
-	    (uc)->cr_uid == (q)->p_cred->p_ruid || \
-	    (ruid) == (q)->p_ucred->cr_uid || \
-	    (uc)->cr_uid == (q)->p_ucred->cr_uid)
+#define CANSIGIO(cr1, cr2) \
+	((cr1)->cr_uid == 0 || \
+	    (cr2)->cr_ruid == (cr2)->cr_ruid || \
+	    (cr2)->cr_uid == (cr2)->cr_ruid || \
+	    (cr2)->cr_ruid == (cr2)->cr_uid || \
+	    (cr2)->cr_uid == (cr2)->cr_uid)
 
 int sugid_coredump;
 SYSCTL_INT(_kern, OID_AUTO, sugid_coredump, CTLFLAG_RW, 
@@ -1612,7 +1612,7 @@ killproc(p, why)
 	CTR3(KTR_PROC, "killproc: proc %p (pid %d, %s)",
 		p, p->p_pid, p->p_comm);
 	log(LOG_ERR, "pid %d (%s), uid %d, was killed: %s\n", p->p_pid, p->p_comm,
-		p->p_cred && p->p_ucred ? p->p_ucred->cr_uid : -1, why);
+		p->p_ucred ? p->p_ucred->cr_uid : -1, why);
 	psignal(p, SIGKILL);
 }
 
@@ -1649,7 +1649,7 @@ sigexit(p, sig)
 			log(LOG_INFO,
 			    "pid %d (%s), uid %d: exited on signal %d%s\n",
 			    p->p_pid, p->p_comm,
-			    p->p_cred && p->p_ucred ? p->p_ucred->cr_uid : -1,
+			    p->p_ucred ? p->p_ucred->cr_uid : -1,
 			    sig &~ WCOREFLAG,
 			    sig & WCOREFLAG ? " (core dumped)" : "");
 	} else {
@@ -1869,8 +1869,7 @@ pgsigio(sigio, sig, checkctty)
 		
 	if (sigio->sio_pgid > 0) {
 		PROC_LOCK(sigio->sio_proc);
-		if (CANSIGIO(sigio->sio_ruid, sigio->sio_ucred,
-		             sigio->sio_proc))
+		if (CANSIGIO(sigio->sio_ucred, sigio->sio_proc->p_ucred))
 			psignal(sigio->sio_proc, sig);
 		PROC_UNLOCK(sigio->sio_proc);
 	} else if (sigio->sio_pgid < 0) {
@@ -1878,7 +1877,7 @@ pgsigio(sigio, sig, checkctty)
 
 		LIST_FOREACH(p, &sigio->sio_pgrp->pg_members, p_pglist) {
 			PROC_LOCK(p);
-			if (CANSIGIO(sigio->sio_ruid, sigio->sio_ucred, p) &&
+			if (CANSIGIO(sigio->sio_ucred, p->p_ucred) &&
 			    (checkctty == 0 || (p->p_flag & P_CONTROLT)))
 				psignal(p, sig);
 			PROC_UNLOCK(p);
diff --git a/sys/kern/p1003_1b.c b/sys/kern/p1003_1b.c
index 569bb6f..cf2c7da 100644
--- a/sys/kern/p1003_1b.c
+++ b/sys/kern/p1003_1b.c
@@ -68,16 +68,17 @@ MALLOC_DEFINE(M_P31B, "p1003.1b", "Posix 1003.1B");
 /*
  * This is stolen from CANSIGNAL in kern_sig:
  *
- * Can process p, with pcred pc, do "write flavor" operations to process q?
+ * Can process with credential cr1 do "write flavor" operations to credential
+ * cr2.  This check needs to use generalized checks.
  */
-#define CAN_AFFECT(p, q) \
-	(!suser_xxx(NULL, p, PRISON_ROOT) || \
-	    (p)->p_cred->pc_ruid == (q)->p_cred->p_ruid || \
-	    (p)->p_ucred->cr_uid == (q)->p_cred->p_ruid || \
-	    (p)->p_cred->pc_ruid == (q)->p_ucred->cr_uid || \
-	    (p)->p_ucred->cr_uid == (q)->p_ucred->cr_uid)
+#define CAN_AFFECT(cr1, cr2) \
+	(!suser_xxx(cr1, NULL, PRISON_ROOT) || \
+	    (c1)->cr_ruid == (cr2)->cr_ruid || \
+	    (c1)->cr_uid == (cr2)->cr_ruid || \
+	    (c1)->cr_ruid == (cr2)->cr_uid || \
+	    (c1)->cr_uid == (cr2)->cr_uid)
 #else
-#define CAN_AFFECT(p, q) (!suser_xxx(NULL, p, PRISON_ROOT))
+#define CAN_AFFECT(cr1, cr2) (!suser_xxx(cr1, NULL, PRISON_ROOT))
 #endif
 
 /*
@@ -99,7 +100,7 @@ int p31b_proc(struct proc *p, pid_t pid, struct proc **pp)
 	{
 		/* Enforce permission policy.
 		 */
-		if (CAN_AFFECT(p, other_proc))
+		if (CAN_AFFECT(p->p_ucred, other_proc->p_ucred))
 			*pp = other_proc;
 		else
 			ret = EPERM;
diff --git a/sys/kern/uipc_usrreq.c b/sys/kern/uipc_usrreq.c
index 33ff735..2907b4e 100644
--- a/sys/kern/uipc_usrreq.c
+++ b/sys/kern/uipc_usrreq.c
@@ -988,8 +988,8 @@ unp_internalize(control, p)
 	if (cm->cmsg_type == SCM_CREDS) {
 		cmcred = (struct cmsgcred *)(cm + 1);
 		cmcred->cmcred_pid = p->p_pid;
-		cmcred->cmcred_uid = p->p_cred->p_ruid;
-		cmcred->cmcred_gid = p->p_cred->p_rgid;
+		cmcred->cmcred_uid = p->p_ucred->cr_ruid;
+		cmcred->cmcred_gid = p->p_ucred->cr_rgid;
 		cmcred->cmcred_euid = p->p_ucred->cr_uid;
 		cmcred->cmcred_ngroups = MIN(p->p_ucred->cr_ngroups,
 							CMGROUP_MAX);
diff --git a/sys/kern/vfs_extattr.c b/sys/kern/vfs_extattr.c
index 89041a6..75d3eb7 100644
--- a/sys/kern/vfs_extattr.c
+++ b/sys/kern/vfs_extattr.c
@@ -1710,8 +1710,8 @@ access(p, uap)
 	 * rather than to modify the potentially shared process structure.
 	 */
 	tmpcred = crdup(cred);
-	tmpcred->cr_uid = p->p_cred->p_ruid;
-	tmpcred->cr_groups[0] = p->p_cred->p_rgid;
+	tmpcred->cr_uid = cred->cr_ruid;
+	tmpcred->cr_groups[0] = cred->cr_rgid;
 	p->p_ucred = tmpcred;
 	NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | NOOBJ, UIO_USERSPACE,
 	    SCARG(uap, path), p);
@@ -3801,7 +3801,7 @@ extattr_set_vp(struct vnode *vp, int attrnamespace, const char *attrname,
 	}
 	cnt = auio.uio_resid;
 	error = VOP_SETEXTATTR(vp, attrnamespace, attrname, &auio,
-	    p->p_cred->pc_ucred, p);
+	    p->p_ucred, p);
 	cnt -= auio.uio_resid;
 	p->p_retval[0] = cnt;
 done:
@@ -3914,7 +3914,7 @@ extattr_get_vp(struct vnode *vp, int attrnamespace, const char *attrname,
 	}
 	cnt = auio.uio_resid;
 	error = VOP_GETEXTATTR(vp, attrnamespace, attrname, &auio,
-	    p->p_cred->pc_ucred, p);
+	    p->p_ucred, p);
 	cnt -= auio.uio_resid;
 	p->p_retval[0] = cnt;
 done:
@@ -3997,7 +3997,7 @@ extattr_delete_vp(struct vnode *vp, int attrnamespace, const char *attrname,
 	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
 
 	error = VOP_SETEXTATTR(vp, attrnamespace, attrname, NULL,
-	    p->p_cred->pc_ucred, p);
+	    p->p_ucred, p);
 
 	VOP_UNLOCK(vp, 0, p);
 	vn_finished_write(mp);
diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
index 89041a6..75d3eb7 100644
--- a/sys/kern/vfs_syscalls.c
+++ b/sys/kern/vfs_syscalls.c
@@ -1710,8 +1710,8 @@ access(p, uap)
 	 * rather than to modify the potentially shared process structure.
 	 */
 	tmpcred = crdup(cred);
-	tmpcred->cr_uid = p->p_cred->p_ruid;
-	tmpcred->cr_groups[0] = p->p_cred->p_rgid;
+	tmpcred->cr_uid = cred->cr_ruid;
+	tmpcred->cr_groups[0] = cred->cr_rgid;
 	p->p_ucred = tmpcred;
 	NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | NOOBJ, UIO_USERSPACE,
 	    SCARG(uap, path), p);
@@ -3801,7 +3801,7 @@ extattr_set_vp(struct vnode *vp, int attrnamespace, const char *attrname,
 	}
 	cnt = auio.uio_resid;
 	error = VOP_SETEXTATTR(vp, attrnamespace, attrname, &auio,
-	    p->p_cred->pc_ucred, p);
+	    p->p_ucred, p);
 	cnt -= auio.uio_resid;
 	p->p_retval[0] = cnt;
 done:
@@ -3914,7 +3914,7 @@ extattr_get_vp(struct vnode *vp, int attrnamespace, const char *attrname,
 	}
 	cnt = auio.uio_resid;
 	error = VOP_GETEXTATTR(vp, attrnamespace, attrname, &auio,
-	    p->p_cred->pc_ucred, p);
+	    p->p_ucred, p);
 	cnt -= auio.uio_resid;
 	p->p_retval[0] = cnt;
 done:
@@ -3997,7 +3997,7 @@ extattr_delete_vp(struct vnode *vp, int attrnamespace, const char *attrname,
 	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
 
 	error = VOP_SETEXTATTR(vp, attrnamespace, attrname, NULL,
-	    p->p_cred->pc_ucred, p);
+	    p->p_ucred, p);
 
 	VOP_UNLOCK(vp, 0, p);
 	vn_finished_write(mp);
diff --git a/sys/nfs/nfs_lock.c b/sys/nfs/nfs_lock.c
index 9fd243a..85bc9d9 100644
--- a/sys/nfs/nfs_lock.c
+++ b/sys/nfs/nfs_lock.c
@@ -236,9 +236,11 @@ nfslockdans(p, ansp)
 
 	/* Let root, or someone who once was root (lockd generally
 	 * switches to the daemon uid once it is done setting up) make 
-	 * this call
+	 * this call.
+	 *
+	 * XXX This authorization check is probably not right.
 	 */
-	if ((error = suser(p)) != 0 && p->p_cred->p_svuid != 0)
+	if ((error = suser(p)) != 0 && p->p_ucred->cr_svuid != 0)
 		return (error);
 
 	/* the version should match, or we're out of sync */
diff --git a/sys/nfsclient/nfs_lock.c b/sys/nfsclient/nfs_lock.c
index 9fd243a..85bc9d9 100644
--- a/sys/nfsclient/nfs_lock.c
+++ b/sys/nfsclient/nfs_lock.c
@@ -236,9 +236,11 @@ nfslockdans(p, ansp)
 
 	/* Let root, or someone who once was root (lockd generally
 	 * switches to the daemon uid once it is done setting up) make 
-	 * this call
+	 * this call.
+	 *
+	 * XXX This authorization check is probably not right.
 	 */
-	if ((error = suser(p)) != 0 && p->p_cred->p_svuid != 0)
+	if ((error = suser(p)) != 0 && p->p_ucred->cr_svuid != 0)
 		return (error);
 
 	/* the version should match, or we're out of sync */
diff --git a/sys/posix4/p1003_1b.c b/sys/posix4/p1003_1b.c
index 569bb6f..cf2c7da 100644
--- a/sys/posix4/p1003_1b.c
+++ b/sys/posix4/p1003_1b.c
@@ -68,16 +68,17 @@ MALLOC_DEFINE(M_P31B, "p1003.1b", "Posix 1003.1B");
 /*
  * This is stolen from CANSIGNAL in kern_sig:
  *
- * Can process p, with pcred pc, do "write flavor" operations to process q?
+ * Can process with credential cr1 do "write flavor" operations to credential
+ * cr2.  This check needs to use generalized checks.
  */
-#define CAN_AFFECT(p, q) \
-	(!suser_xxx(NULL, p, PRISON_ROOT) || \
-	    (p)->p_cred->pc_ruid == (q)->p_cred->p_ruid || \
-	    (p)->p_ucred->cr_uid == (q)->p_cred->p_ruid || \
-	    (p)->p_cred->pc_ruid == (q)->p_ucred->cr_uid || \
-	    (p)->p_ucred->cr_uid == (q)->p_ucred->cr_uid)
+#define CAN_AFFECT(cr1, cr2) \
+	(!suser_xxx(cr1, NULL, PRISON_ROOT) || \
+	    (c1)->cr_ruid == (cr2)->cr_ruid || \
+	    (c1)->cr_uid == (cr2)->cr_ruid || \
+	    (c1)->cr_ruid == (cr2)->cr_uid || \
+	    (c1)->cr_uid == (cr2)->cr_uid)
 #else
-#define CAN_AFFECT(p, q) (!suser_xxx(NULL, p, PRISON_ROOT))
+#define CAN_AFFECT(cr1, cr2) (!suser_xxx(cr1, NULL, PRISON_ROOT))
 #endif
 
 /*
@@ -99,7 +100,7 @@ int p31b_proc(struct proc *p, pid_t pid, struct proc **pp)
 	{
 		/* Enforce permission policy.
 		 */
-		if (CAN_AFFECT(p, other_proc))
+		if (CAN_AFFECT(p->p_ucred, other_proc->p_ucred))
 			*pp = other_proc;
 		else
 			ret = EPERM;
diff --git a/sys/sys/filedesc.h b/sys/sys/filedesc.h
index 273ddf1..c0cb850 100644
--- a/sys/sys/filedesc.h
+++ b/sys/sys/filedesc.h
@@ -117,7 +117,6 @@ struct	sigio {
 	struct	sigio **sio_myref;	/* location of the pointer that holds
 					 * the reference to this structure */
 	struct	ucred *sio_ucred;	/* current credentials */
-	uid_t	sio_ruid;		/* real user id */
 	pid_t	sio_pgid;		/* pgid for signals */
 };
 #define	sio_proc	sio_u.siu_proc
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index d953b1d..3201669 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -156,7 +156,7 @@ struct	proc {
 	LIST_ENTRY(proc) p_list;	/* (d) List of all processes. */
 
 	/* substructures: */
-	struct	pcred *p_cred;		/* (c + k) Process owner's identity. */
+	struct	ucred *p_ucred;		/* (c + k) Process owner's identity. */
 	struct	filedesc *p_fd;		/* (b) Ptr to open files structure. */
 	struct	pstats *p_stats;	/* (b) Accounting/statistics (CPU). */
 	struct	plimit *p_limit;	/* (m) Process limits. */
@@ -166,7 +166,6 @@ struct	proc {
 #define	p_sigignore	p_procsig->ps_sigignore
 #define	p_sigcatch	p_procsig->ps_sigcatch
 
-#define	p_ucred		p_cred->pc_ucred
 #define	p_rlimit	p_limit->pl_rlimit
 
 	int	p_flag;			/* (c) P_* flags. */
@@ -337,23 +336,6 @@ struct	proc {
 #define	P_CAN_SCHED	3
 #define	P_CAN_DEBUG	4
 
-/*
- * MOVE TO ucred.h?
- *
- * Shareable process credentials (always resident).  This includes a reference
- * to the current user credentials as well as real and saved ids that may be
- * used to change ids.
- */
-struct	pcred {
-	struct	ucred *pc_ucred;	/* Current credentials. */
-	uid_t	p_ruid;			/* Real user id. */
-	uid_t	p_svuid;		/* Saved effective user id. */
-	gid_t	p_rgid;			/* Real group id. */
-	gid_t	p_svgid;		/* Saved effective group id. */
-	int	p_refcnt;		/* Number of references. */
-	struct	uidinfo *p_uidinfo;	/* Per uid resource consumption. */
-};
-
 #ifdef _KERNEL
 
 #ifdef MALLOC_DECLARE
diff --git a/sys/sys/ucred.h b/sys/sys/ucred.h
index c48df00..356cca2 100644
--- a/sys/sys/ucred.h
+++ b/sys/sys/ucred.h
@@ -50,9 +50,14 @@
 struct ucred {
 	u_int	cr_ref;			/* reference count */
 	uid_t	cr_uid;			/* effective user id */
+	uid_t	cr_ruid;		/* real user id */
+	uid_t	cr_svuid;		/* saved user id */
 	short	cr_ngroups;		/* number of groups */
 	gid_t	cr_groups[NGROUPS];	/* groups */
-	struct	uidinfo *cr_uidinfo;	/* per uid resource consumption */
+	gid_t	cr_rgid;		/* real group id */
+	gid_t	cr_svgid;		/* saved user id */
+	struct	uidinfo *cr_uidinfo;	/* per euid resource consumption */
+	struct	uidinfo *cr_ruidinfo;	/* per ruid resource consumption */
 	struct	prison *cr_prison;	/* jail(4) */
 	struct	mtx cr_mtx;		/* protect refcount */
 };
@@ -77,8 +82,12 @@ struct xucred {
 
 struct proc;
 
-void		change_euid __P((struct proc *p, uid_t euid));
-void		change_ruid __P((struct proc *p, uid_t ruid));
+void		change_egid __P((struct ucred *newcred, gid_t egid));
+void		change_euid __P((struct ucred *newcred, uid_t euid));
+void		change_rgid __P((struct ucred *newcred, gid_t rgid));
+void		change_ruid __P((struct ucred *newcred, uid_t ruid));
+void		change_svgid __P((struct ucred *newcred, gid_t svgid));
+void		change_svuid __P((struct ucred *newcred, uid_t svuid));
 struct ucred	*crcopy __P((struct ucred *cr));
 struct ucred	*crdup __P((struct ucred *cr));
 void		crfree __P((struct ucred *cr));
diff --git a/sys/ufs/ufs/ufs_extattr.c b/sys/ufs/ufs/ufs_extattr.c
index e77e9fb..817fde3 100644
--- a/sys/ufs/ufs/ufs_extattr.c
+++ b/sys/ufs/ufs/ufs_extattr.c
@@ -621,7 +621,7 @@ ufs_extattr_enable(struct ufsmount *ump, int attrnamespace,
 	auio.uio_rw = UIO_READ;
 	auio.uio_procp = (struct proc *) p;
 
-	VOP_LEASE(backing_vnode, p, p->p_cred->pc_ucred, LEASE_WRITE);
+	VOP_LEASE(backing_vnode, p, p->p_ucred, LEASE_WRITE);
 	vn_lock(backing_vnode, LK_SHARED | LK_NOPAUSE | LK_RETRY, p);
 	error = VOP_READ(backing_vnode, &auio, IO_NODELOCKED,
 	    ump->um_extattr.uepm_ucred);
@@ -702,7 +702,7 @@ ufs_extattrctl(struct mount *mp, int cmd, struct vnode *filename_vp,
 	 * Processes with privilege, but in jail, are not allowed to
 	 * configure extended attributes.
 	 */
-	if ((error = suser_xxx(p->p_cred->pc_ucred, p, 0))) {
+	if ((error = suser_xxx(p->p_ucred, p, 0))) {
 		if (filename_vp != NULL)
 			VOP_UNLOCK(filename_vp, 0, p);
 		return (error);
diff --git a/sys/ufs/ufs/ufs_vfsops.c b/sys/ufs/ufs/ufs_vfsops.c
index 5c293df..6b8905b 100644
--- a/sys/ufs/ufs/ufs_vfsops.c
+++ b/sys/ufs/ufs/ufs_vfsops.c
@@ -108,14 +108,14 @@ ufs_quotactl(mp, cmds, uid, arg, p)
 	int cmd, type, error;
 
 	if (uid == -1)
-		uid = p->p_cred->p_ruid;
+		uid = p->p_ucred->cr_ruid;
 	cmd = cmds >> SUBCMDSHIFT;
 
 	switch (cmd) {
 	case Q_SYNC:
 		break;
 	case Q_GETQUOTA:
-		if (uid == p->p_cred->p_ruid)
+		if (uid == p->p_ucred->cr_ruid)
 			break;
 		/* fall through */
 	default: