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

1 files changed, 12 insertions, 51 deletions

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.
  */