o Replace calls to p_can(..., P_CAN_xxx) with calls to p_canxxx().

  The p_can(...) construct was a premature (and, it turns out,
  awkward) abstraction.  The individual calls to p_canxxx() better
  reflect differences between the inter-process authorization checks,
  such as differing checks based on the type of signal.  This has
  a side effect of improving code readability.
o Replace direct credential authorization checks in ktrace() with
  invocation of p_candebug(), while maintaining the special case
  check of KTR_ROOT.  This allows ktrace() to "play more nicely"
  with new mandatory access control schemes, as well as making its
  authorization checks consistent with other "debugging class"
  checks.
o Eliminate "privused" construct for p_can*() calls which allowed the
  caller to determine if privilege was required for successful
  evaluation of the access control check.  This primitive is currently
  unused, and as such, serves only to complicate the API.

Approved by:	({procfs,linprocfs} changes) des
Obtained from:	TrustedBSD Project

17 files changed, 63 insertions, 111 deletions

diff --git a/sys/compat/linprocfs/linprocfs.c b/sys/compat/linprocfs/linprocfs.c
index f8e76e7..f41d536 100644
--- a/sys/compat/linprocfs/linprocfs.c
+++ b/sys/compat/linprocfs/linprocfs.c
@@ -604,7 +604,7 @@ linprocfs_doproccmdline(PFS_FILL_ARGS)
 	 * Linux behaviour is to return zero-length in this case.
 	 */
 
-	if (p->p_args && (ps_argsopen || !p_can(curp, p, P_CAN_SEE, NULL))) {
+	if (p->p_args && (ps_argsopen || !p_cansee(curp, p))) {
 		sbuf_bcpy(sb, p->p_args->ar_args, p->p_args->ar_length);
 	} else if (p != curp) {
 		sbuf_printf(sb, "%.*s", MAXCOMLEN, p->p_comm);
diff --git a/sys/fs/procfs/procfs_ctl.c b/sys/fs/procfs/procfs_ctl.c
index a507349..30b61f2 100644
--- a/sys/fs/procfs/procfs_ctl.c
+++ b/sys/fs/procfs/procfs_ctl.c
@@ -119,7 +119,7 @@ procfs_control(curp, p, op)
 	 * debug.
 	 */
 	if (op != PROCFS_CTL_DETACH &&
-	    ((error = p_can(curp, p, P_CAN_DEBUG, NULL))))
+	    ((error = p_candebug(curp, p))))
 		return (error);
 
 	/*
diff --git a/sys/fs/procfs/procfs_dbregs.c b/sys/fs/procfs/procfs_dbregs.c
index cd64a34..d61b8c9 100644
--- a/sys/fs/procfs/procfs_dbregs.c
+++ b/sys/fs/procfs/procfs_dbregs.c
@@ -68,7 +68,7 @@ procfs_dodbregs(curp, p, pfs, uio)
 	char *kv;
 	int kl;
 
-	if (p_can(curp, p, P_CAN_DEBUG, NULL))
+	if (p_candebug(curp, p))
 		return (EPERM);
 	kl = sizeof(r);
 	kv = (char *) &r;
diff --git a/sys/fs/procfs/procfs_fpregs.c b/sys/fs/procfs/procfs_fpregs.c
index c71e444..9b6cd3a 100644
--- a/sys/fs/procfs/procfs_fpregs.c
+++ b/sys/fs/procfs/procfs_fpregs.c
@@ -65,7 +65,7 @@ procfs_dofpregs(curp, p, pfs, uio)
 	char *kv;
 	int kl;
 
-	if (p_can(curp, p, P_CAN_DEBUG, NULL))
+	if (p_candebug(curp, p))
 		return EPERM;
 	kl = sizeof(r);
 	kv = (char *) &r;
diff --git a/sys/fs/procfs/procfs_mem.c b/sys/fs/procfs/procfs_mem.c
index e109146..dcba9b0 100644
--- a/sys/fs/procfs/procfs_mem.c
+++ b/sys/fs/procfs/procfs_mem.c
@@ -263,7 +263,7 @@ procfs_domem(curp, p, pfs, uio)
  	 * All in all, quite yucky.
  	 */
  
- 	if (p_can(curp, p, P_CAN_DEBUG, NULL) &&
+ 	if (p_candebug(curp, p) &&
 	    !(uio->uio_rw == UIO_READ &&
 	      procfs_kmemaccess(curp)))
  		return EPERM;
diff --git a/sys/fs/procfs/procfs_regs.c b/sys/fs/procfs/procfs_regs.c
index c7eeb1c..6a00ecd 100644
--- a/sys/fs/procfs/procfs_regs.c
+++ b/sys/fs/procfs/procfs_regs.c
@@ -66,7 +66,7 @@ procfs_doregs(curp, p, pfs, uio)
 	char *kv;
 	int kl;
 
-	if (p_can(curp, p, P_CAN_DEBUG, NULL))
+	if (p_candebug(curp, p))
 		return EPERM;
 	kl = sizeof(r);
 	kv = (char *) &r;
diff --git a/sys/fs/procfs/procfs_status.c b/sys/fs/procfs/procfs_status.c
index 0f57e49..3a2a814 100644
--- a/sys/fs/procfs/procfs_status.c
+++ b/sys/fs/procfs/procfs_status.c
@@ -219,7 +219,7 @@ procfs_docmdline(curp, p, pfs, uio)
 	 * Linux behaviour is to return zero-length in this case.
 	 */
 
-	if (p->p_args && (ps_argsopen || !p_can(curp, p, P_CAN_SEE, NULL))) {
+	if (p->p_args && (ps_argsopen || !p_cansee(curp, p))) {
 		bp = p->p_args->ar_args;
 		buflen = p->p_args->ar_length;
 		buf = 0;
diff --git a/sys/fs/procfs/procfs_vnops.c b/sys/fs/procfs/procfs_vnops.c
index 4ca89ac..bc280c78 100644
--- a/sys/fs/procfs/procfs_vnops.c
+++ b/sys/fs/procfs/procfs_vnops.c
@@ -143,7 +143,7 @@ procfs_open(ap)
 	p2 = PFIND(pfs->pfs_pid);
 	if (p2 == NULL)
 		return (ENOENT);
-	if (pfs->pfs_pid && p_can(ap->a_p, p2, P_CAN_SEE, NULL)) {
+	if (pfs->pfs_pid && p_cansee(ap->a_p, p2)) {
 		error = ENOENT;
 		goto out;
 	}
@@ -157,7 +157,7 @@ procfs_open(ap)
 		}
 
 		p1 = ap->a_p;
-		if (p_can(p1, p2, P_CAN_DEBUG, NULL) &&
+		if (p_candebug(p1, p2) &&
 		    !procfs_kmemaccess(p1)) {
 			error = EPERM;
 		}
@@ -242,7 +242,7 @@ procfs_ioctl(ap)
 		return ENOTTY;
 	}
 
-	if ((error = p_can(p, procp, P_CAN_DEBUG, NULL))) {
+	if ((error = p_candebug(p, procp))) {
 		PROC_UNLOCK(procp);
 		return (error == ESRCH ? ENOENT : error);
 	}
@@ -408,7 +408,7 @@ procfs_getattr(ap)
 			return (ENOENT);
 		}
 
-		if (p_can(ap->a_p, procp, P_CAN_SEE, NULL)) {
+		if (p_cansee(ap->a_p, procp)) {
 			PROC_UNLOCK(procp);
 			return (ENOENT);
 		}
@@ -625,7 +625,7 @@ procfs_access(ap)
 		procp = PFIND(pfs->pfs_pid);
 		if (procp == NULL)
 			return (ENOENT);
-		if (p_can(ap->a_p, procp, P_CAN_SEE, NULL)) {
+		if (p_cansee(ap->a_p, procp)) {
 			PROC_UNLOCK(procp);
 			return (ENOENT);
 		}
@@ -699,7 +699,7 @@ procfs_lookup(ap)
 		if (p == NULL)
 			break;
 
-		if (p_can(curp, p, P_CAN_SEE, NULL)) {
+		if (p_cansee(curp, p)) {
 			PROC_UNLOCK(p);
 			break;
 		}
@@ -800,7 +800,7 @@ procfs_readdir(ap)
 		p = PFIND(pfs->pfs_pid);
 		if (p == NULL)
 			break;
-		if (p_can(curproc, p, P_CAN_SEE, NULL)) {
+		if (p_cansee(curproc, p)) {
 			PROC_UNLOCK(p);
 			break;
 		}
@@ -868,11 +868,11 @@ procfs_readdir(ap)
 					p = LIST_NEXT(p, p_list);
 					if (p == NULL)
 						goto done;
-					if (p_can(curproc, p, P_CAN_SEE, NULL))
+					if (p_cansee(curproc, p))
 						continue;
 					pcnt++;
 				}
-				while (p_can(curproc, p, P_CAN_SEE, NULL)) {
+				while (p_cansee(curproc, p)) {
 					p = LIST_NEXT(p, p_list);
 					if (p == NULL)
 						goto done;
diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c
index d4d588e..4f8b61b 100644
--- a/sys/kern/kern_event.c
+++ b/sys/kern/kern_event.c
@@ -172,7 +172,7 @@ filt_procattach(struct knote *kn)
 	p = pfind(kn->kn_id);
 	if (p == NULL)
 		return (ESRCH);
-	if ((error = p_can(curproc, p, P_CAN_SEE, NULL))) {
+	if ((error = p_cansee(curproc, p))) {
 		PROC_UNLOCK(p);
 		return (error);
 	}
diff --git a/sys/kern/kern_ktrace.c b/sys/kern/kern_ktrace.c
index 15b51c8..a37ad22 100644
--- a/sys/kern/kern_ktrace.c
+++ b/sys/kern/kern_ktrace.c
@@ -521,30 +521,20 @@ ktrwrite(vp, kth, uio)
  * more permissions than the caller.  KTRFAC_ROOT signifies that
  * root previously set the tracing status on the target process, and
  * so, only root may further change it.
- *
- * XXX: These checks are stronger than for ptrace()
- * XXX: This check should be p_can(... P_CAN_DEBUG ...);
- *
- * TODO: check groups.  use caller effective gid.
  */
 static int
 ktrcanset(callp, targetp)
 	struct proc *callp, *targetp;
 {
-	struct ucred *callcr = callp->p_ucred;
-	struct ucred *targetcr = targetp->p_ucred;
 
-	if (prison_check(callcr, targetcr))
+	if (targetp->p_traceflag & KTRFAC_ROOT &&
+	    suser_xxx(NULL, callp, PRISON_ROOT))
 		return (0);
-	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) ||
-	     !suser_xxx(callcr, NULL, PRISON_ROOT))
-		return (1);
 
-	return (0);
+	if (p_candebug(callp, targetp) != 0)
+		return (0);
+
+	return (1);
 }
 
 #endif /* KTRACE */
diff --git a/sys/kern/kern_proc.c b/sys/kern/kern_proc.c
index 883e2fa..50f3446 100644
--- a/sys/kern/kern_proc.c
+++ b/sys/kern/kern_proc.c
@@ -585,7 +585,7 @@ sysctl_kern_proc(SYSCTL_HANDLER_ARGS)
 		p = pfind((pid_t)name[0]);
 		if (!p)
 			return (0);
-		if (p_can(curproc, p, P_CAN_SEE, NULL)) {
+		if (p_cansee(curproc, p)) {
 			PROC_UNLOCK(p);
 			return (0);
 		}
@@ -616,7 +616,7 @@ sysctl_kern_proc(SYSCTL_HANDLER_ARGS)
 			/*
 			 * Show a user only appropriate processes.
 			 */
-			if (p_can(curproc, p, P_CAN_SEE, NULL))
+			if (p_cansee(curproc, p))
 				continue;
 			/*
 			 * Skip embryonic processes.
@@ -658,7 +658,7 @@ sysctl_kern_proc(SYSCTL_HANDLER_ARGS)
 				break;
 			}
 
-			if (p_can(curproc, p, P_CAN_SEE, NULL))
+			if (p_cansee(curproc, p))
 				continue;
 
 			error = sysctl_out_proc(p, req, doingzomb);
@@ -694,7 +694,7 @@ sysctl_kern_proc_args(SYSCTL_HANDLER_ARGS)
 	if (!p)
 		return (0);
 
-	if ((!ps_argsopen) && p_can(curproc, p, P_CAN_SEE, NULL)) {
+	if ((!ps_argsopen) && p_cansee(curproc, p)) {
 		PROC_UNLOCK(p);
 		return (0);
 	}
diff --git a/sys/kern/kern_prot.c b/sys/kern/kern_prot.c
index ceb8f5a..1c6ce77 100644
--- a/sys/kern/kern_prot.c
+++ b/sys/kern/kern_prot.c
@@ -151,7 +151,7 @@ getpgid(p, uap)
 	else {
 		if ((pt = pfind(uap->pid)) == NULL)
 			return ESRCH;
-		if ((error = p_can(p, pt, P_CAN_SEE, NULL))) {
+		if ((error = p_cansee(p, pt))) {
 			PROC_UNLOCK(pt);
 			return (error);
 		}
@@ -183,7 +183,7 @@ getsid(p, uap)
 	else {
 		if ((pt = pfind(uap->pid)) == NULL)
 			return ESRCH;
-		if ((error = p_can(p, pt, P_CAN_SEE, NULL))) {
+		if ((error = p_cansee(p, pt))) {
 			PROC_UNLOCK(pt);
 			return (error);
 		}
@@ -370,7 +370,7 @@ setpgid(curp, uap)
 				PROC_UNLOCK(targp);
 			return (ESRCH);
 		}
-		if ((error = p_can(curproc, targp, P_CAN_SEE, NULL))) {
+		if ((error = p_cansee(curproc, targp))) {
 			PROC_UNLOCK(targp);
 			return (error);
 		}
@@ -1086,13 +1086,10 @@ u_cansee(struct ucred *u1, struct ucred *u2)
 	return (0);
 }
 
-static int
-p_cansee(struct proc *p1, struct proc *p2, int *privused)
+int
+p_cansee(struct proc *p1, struct proc *p2)
 {
 
-	/* XXX: privused is going away, so don't do that here. */
-	if (privused != NULL)
-		*privused = 0;
 	/* Wrap u_cansee() for all functionality. */
 	return (u_cansee(p1->p_ucred, p2->p_ucred));
 }
@@ -1167,14 +1164,11 @@ p_cansignal(struct proc *p1, struct proc *p2, int signum)
         return (0);
 }
 
-static int
-p_cansched(struct proc *p1, struct proc *p2, int *privused)
+int
+p_cansched(struct proc *p1, struct proc *p2)
 {
 	int error;
 
-	if (privused != NULL)
-		*privused = 0;
-
 	if (p1 == p2)
 		return (0);
 
@@ -1186,31 +1180,22 @@ p_cansched(struct proc *p1, struct proc *p2, int *privused)
 	if (p1->p_ucred->cr_uid == p2->p_ucred->cr_ruid)
 		return (0);
 
-	if (!suser_xxx(0, p1, PRISON_ROOT)) {
-		if (privused != NULL)
-			*privused = 1;
+	if (!suser_xxx(0, p1, PRISON_ROOT))
 		return (0);
-	}
 
 #ifdef CAPABILITIES
-	if (!cap_check_xxx(0, p1, CAP_SYS_NICE, PRISON_ROOT)) {
-		if (privused != NULL)
-			*privused = 1;
+	if (!cap_check_xxx(0, p1, CAP_SYS_NICE, PRISON_ROOT))
 		return (0);
-	}
 #endif
 
 	return (EPERM);
 }
 
-static int
-p_candebug(struct proc *p1, struct proc *p2, int *privused)
+int
+p_candebug(struct proc *p1, struct proc *p2)
 {
 	int error;
 
-	if (privused != NULL)
-		*privused = 0;
-
 	if (p1 == p2)
 		return (0);
 
@@ -1222,12 +1207,9 @@ p_candebug(struct proc *p1, struct proc *p2, int *privused)
 	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) {
+	    p2->p_flag & P_SUGID)
 		if ((error = suser_xxx(0, p1, PRISON_ROOT)))
 			return (error);
-		if (privused != NULL)
-			*privused = 1;
-	}
 
 	/* can't trace init when securelevel > 0 */
 	if (securelevel > 0 && p2->p_pid == 1)
@@ -1236,27 +1218,6 @@ p_candebug(struct proc *p1, struct proc *p2, int *privused)
 	return (0);
 }
 
-int
-p_can(struct proc *p1, struct proc *p2, int operation,
-    int *privused)
-{
-
-	switch(operation) {   
-	case P_CAN_SEE:
-		return (p_cansee(p1, p2, privused));
-  
-	case P_CAN_SCHED:
-		return (p_cansched(p1, p2, privused));
-
-	case P_CAN_DEBUG:
-		return (p_candebug(p1, p2, privused));
-
-	default:
-		panic("p_can: invalid operation");
-	}
-}
-
-
 /*
  * Allocate a zeroed cred structure.
  */
diff --git a/sys/kern/kern_resource.c b/sys/kern/kern_resource.c
index f7503db..6e9ee85 100644
--- a/sys/kern/kern_resource.c
+++ b/sys/kern/kern_resource.c
@@ -99,7 +99,7 @@ getpriority(curp, uap)
 			p = pfind(uap->who);
 			if (p == NULL)
 				break;
-			if (p_can(curp, p, P_CAN_SEE, NULL) == 0)
+			if (p_cansee(curp, p) == 0)
 				low = p->p_nice;
 			PROC_UNLOCK(p);
 		}
@@ -113,7 +113,7 @@ getpriority(curp, uap)
 		else if ((pg = pgfind(uap->who)) == NULL)
 			break;
 		LIST_FOREACH(p, &pg->pg_members, p_pglist) {
-			if (!p_can(curp, p, P_CAN_SEE, NULL) && p->p_nice < low)
+			if (!p_cansee(curp, p) && p->p_nice < low)
 				low = p->p_nice;
 		}
 		break;
@@ -124,7 +124,7 @@ getpriority(curp, uap)
 			uap->who = curp->p_ucred->cr_uid;
 		sx_slock(&allproc_lock);
 		LIST_FOREACH(p, &allproc, p_list)
-			if (!p_can(curp, p, P_CAN_SEE, NULL) &&
+			if (!p_cansee(curp, p) &&
 			    p->p_ucred->cr_uid == uap->who &&
 			    p->p_nice < low)
 				low = p->p_nice;
@@ -165,7 +165,7 @@ setpriority(curp, uap)
 			p = pfind(uap->who);
 			if (p == 0)
 				break;
-			if (p_can(curp, p, P_CAN_SEE, NULL) == 0)
+			if (p_cansee(curp, p) == 0)
 				error = donice(curp, p, uap->prio);
 			PROC_UNLOCK(p);
 		}
@@ -180,7 +180,7 @@ setpriority(curp, uap)
 		else if ((pg = pgfind(uap->who)) == NULL)
 			break;
 		LIST_FOREACH(p, &pg->pg_members, p_pglist) {
-			if (!p_can(curp, p, P_CAN_SEE, NULL)) {
+			if (!p_cansee(curp, p)) {
 				error = donice(curp, p, uap->prio);
 				found++;
 			}
@@ -194,7 +194,7 @@ setpriority(curp, uap)
 		sx_slock(&allproc_lock);
 		LIST_FOREACH(p, &allproc, p_list)
 			if (p->p_ucred->cr_uid == uap->who &&
-			    !p_can(curp, p, P_CAN_SEE, NULL)) {
+			    !p_cansee(curp, p)) {
 				error = donice(curp, p, uap->prio);
 				found++;
 			}
@@ -216,7 +216,7 @@ donice(curp, chgp, n)
 {
 	int	error;
 
-	if ((error = p_can(curp, chgp, P_CAN_SCHED, NULL)))
+	if ((error = p_cansched(curp, chgp)))
 		return (error);
 	if (n > PRIO_MAX)
 		n = PRIO_MAX;
@@ -263,13 +263,13 @@ rtprio(curp, uap)
 
 	switch (uap->function) {
 	case RTP_LOOKUP:
-		if ((error = p_can(curp, p, P_CAN_SEE, NULL)))
+		if ((error = p_cansee(curp, p)))
 			break;
 		pri_to_rtp(&p->p_pri, &rtp);
 		error = copyout(&rtp, uap->rtp, sizeof(struct rtprio));
 		break;
 	case RTP_SET:
-		if ((error = p_can(curp, p, P_CAN_SCHED, NULL)) ||
+		if ((error = p_cansched(curp, p)) ||
 		    (error = copyin(uap->rtp, &rtp, sizeof(struct rtprio))))
 			break;
 		/* disallow setting rtprio in most cases if not superuser */
diff --git a/sys/kern/p1003_1b.c b/sys/kern/p1003_1b.c
index 5b9bee0..1c356e3 100644
--- a/sys/kern/p1003_1b.c
+++ b/sys/kern/p1003_1b.c
@@ -122,7 +122,7 @@ int sched_setparam(struct proc *p,
 			return (ESRCH);
 	}
 
-	e = p_can(p, targetp, P_CAN_SCHED, NULL);
+	e = p_cansched(p, targetp);
 	PROC_UNLOCK(targetp);
 	if (e)
 		return (e);
@@ -148,7 +148,7 @@ int sched_getparam(struct proc *p,
 			return (ESRCH);
 	}
 
-	e = p_can(p, targetp, P_CAN_SEE, NULL);
+	e = p_cansee(p, targetp);
 	PROC_UNLOCK(targetp);
 	if (e)
 		return (e);
@@ -180,7 +180,7 @@ int sched_setscheduler(struct proc *p,
 			return (ESRCH);
 	}
 
-	e = p_can(p, targetp, P_CAN_SCHED, NULL);
+	e = p_cansched(p, targetp);
 	PROC_UNLOCK(targetp);
 	if (e)
 		return (e);
@@ -205,7 +205,7 @@ int sched_getscheduler(struct proc *p,
 			return (ESRCH);
 	}
 
-	e = p_can(p, targetp, P_CAN_SEE, NULL);
+	e = p_cansee(p, targetp);
 	PROC_UNLOCK(targetp);
 	if (e)
 		return (e);
@@ -246,7 +246,7 @@ int sched_rr_get_interval(struct proc *p,
 			return (ESRCH);
 	}
 
-	e = p_can(p, targetp, P_CAN_SEE, NULL);
+	e = p_cansee(p, targetp);
 	PROC_UNLOCK(targetp);
 	if (e)
 		return (e);
diff --git a/sys/kern/sys_process.c b/sys/kern/sys_process.c
index 799608d..66d7e67 100644
--- a/sys/kern/sys_process.c
+++ b/sys/kern/sys_process.c
@@ -220,7 +220,7 @@ ptrace(curp, uap)
 		if ((p = pfind(uap->pid)) == NULL)
 			return ESRCH;
 	}
-	if (p_can(curp, p, P_CAN_SEE, NULL)) {
+	if (p_cansee(curp, p)) {
 		PROC_UNLOCK(p);
 		return (ESRCH);
 	}
@@ -246,7 +246,7 @@ ptrace(curp, uap)
 			return EBUSY;
 		}
 
-		if ((error = p_can(curp, p, P_CAN_DEBUG, NULL))) {
+		if ((error = p_candebug(curp, p))) {
 			PROC_UNLOCK(p);
 			return error;
 		}
diff --git a/sys/posix4/p1003_1b.c b/sys/posix4/p1003_1b.c
index 5b9bee0..1c356e3 100644
--- a/sys/posix4/p1003_1b.c
+++ b/sys/posix4/p1003_1b.c
@@ -122,7 +122,7 @@ int sched_setparam(struct proc *p,
 			return (ESRCH);
 	}
 
-	e = p_can(p, targetp, P_CAN_SCHED, NULL);
+	e = p_cansched(p, targetp);
 	PROC_UNLOCK(targetp);
 	if (e)
 		return (e);
@@ -148,7 +148,7 @@ int sched_getparam(struct proc *p,
 			return (ESRCH);
 	}
 
-	e = p_can(p, targetp, P_CAN_SEE, NULL);
+	e = p_cansee(p, targetp);
 	PROC_UNLOCK(targetp);
 	if (e)
 		return (e);
@@ -180,7 +180,7 @@ int sched_setscheduler(struct proc *p,
 			return (ESRCH);
 	}
 
-	e = p_can(p, targetp, P_CAN_SCHED, NULL);
+	e = p_cansched(p, targetp);
 	PROC_UNLOCK(targetp);
 	if (e)
 		return (e);
@@ -205,7 +205,7 @@ int sched_getscheduler(struct proc *p,
 			return (ESRCH);
 	}
 
-	e = p_can(p, targetp, P_CAN_SEE, NULL);
+	e = p_cansee(p, targetp);
 	PROC_UNLOCK(targetp);
 	if (e)
 		return (e);
@@ -246,7 +246,7 @@ int sched_rr_get_interval(struct proc *p,
 			return (ESRCH);
 	}
 
-	e = p_can(p, targetp, P_CAN_SEE, NULL);
+	e = p_cansee(p, targetp);
 	PROC_UNLOCK(targetp);
 	if (e)
 		return (e);
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index 277fbee..35b5ea4 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -518,8 +518,9 @@ void	fork_return __P((struct proc *, struct trapframe *));
 int	inferior __P((struct proc *p));
 int	leavepgrp __P((struct proc *p));
 void	mi_switch __P((void));
-int	p_can __P((struct proc *p1, struct proc *p2, int operation,
-	    int *privused));
+int	p_candebug __P((struct proc *p1, struct proc *p2));
+int	p_cansee __P((struct proc *p1, struct proc *p2));
+int	p_cansched __P((struct proc *p1, struct proc *p2));
 int	p_cansignal __P((struct proc *p1, struct proc *p2, int signum));
 int	p_trespass __P((struct proc *p1, struct proc *p2));
 void	procinit __P((void));