o Move per-process jail pointer (p->pr_prison) to inside of the subject

  credential structure, ucred (cr->cr_prison).
o Allow jail inheritence to be a function of credential inheritence.
o Abstract prison structure reference counting behind pr_hold() and
  pr_free(), invoked by the similarly named credential reference
  management functions, removing this code from per-ABI fork/exit code.
o Modify various jail() functions to use struct ucred arguments instead
  of struct proc arguments.
o Introduce jailed() function to determine if a credential is jailed,
  rather than directly checking pointers all over the place.
o Convert PRISON_CHECK() macro to prison_check() function.
o Move jail() function prototypes to jail.h.
o Emulate the P_JAILED flag in fill_kinfo_proc() and no longer set the
  flag in the process flags field itself.
o Eliminate that "const" qualifier from suser/p_can/etc to reflect
  mutex use.

Notes:

o Some further cleanup of the linux/jail code is still required.
o It's now possible to consider resolving some of the process vs
  credential based permission checking confusion in the socket code.
o Mutex protection of struct prison is still not present, and is
  required to protect the reference count plus some fields in the
  structure.

Reviewed by:	freebsd-arch
Obtained from:	TrustedBSD Project

4 files changed, 8 insertions, 16 deletions

diff --git a/sys/compat/linprocfs/linprocfs.c b/sys/compat/linprocfs/linprocfs.c
index 749d16a..8ba6c41 100644
--- a/sys/compat/linprocfs/linprocfs.c
+++ b/sys/compat/linprocfs/linprocfs.c
@@ -44,7 +44,6 @@
 #include <sys/param.h>
 #include <sys/blist.h>
 #include <sys/dkstat.h>
-#include <sys/jail.h>
 #include <sys/kernel.h>
 #include <sys/proc.h>
 #include <sys/resourcevar.h>
@@ -52,6 +51,7 @@
 #include <sys/systm.h>
 #include <sys/tty.h>
 #include <sys/vnode.h>
+#include <sys/jail.h>
 
 #include <vm/vm.h>
 #include <vm/pmap.h>
diff --git a/sys/compat/linprocfs/linprocfs_misc.c b/sys/compat/linprocfs/linprocfs_misc.c
index 749d16a..8ba6c41 100644
--- a/sys/compat/linprocfs/linprocfs_misc.c
+++ b/sys/compat/linprocfs/linprocfs_misc.c
@@ -44,7 +44,6 @@
 #include <sys/param.h>
 #include <sys/blist.h>
 #include <sys/dkstat.h>
-#include <sys/jail.h>
 #include <sys/kernel.h>
 #include <sys/proc.h>
 #include <sys/resourcevar.h>
@@ -52,6 +51,7 @@
 #include <sys/systm.h>
 #include <sys/tty.h>
 #include <sys/vnode.h>
+#include <sys/jail.h>
 
 #include <vm/vm.h>
 #include <vm/pmap.h>
diff --git a/sys/compat/linux/linux_mib.c b/sys/compat/linux/linux_mib.c
index 8482dd9..35d4a25 100644
--- a/sys/compat/linux/linux_mib.c
+++ b/sys/compat/linux/linux_mib.c
@@ -117,10 +117,11 @@ get_prison(struct proc *p)
 	register struct prison *pr;
 	register struct linux_prison *lpr;
 
-	pr = p->p_prison;
-	if (pr == NULL)
+	if (!jailed(p->p_ucred))
 		return (NULL);
 
+	pr = p->p_ucred->cr_prison;
+
 	if (pr->pr_linux == NULL) {
 		MALLOC(lpr, struct linux_prison *, sizeof *lpr,
 		    M_PRISON, M_WAITOK|M_ZERO);
@@ -137,7 +138,7 @@ linux_get_osname(p)
 	register struct prison *pr;
 	register struct linux_prison *lpr;
 
-	pr = p->p_prison;
+	pr = p->p_ucred->cr_prison;
 	if (pr != NULL && pr->pr_linux != NULL) {
 		lpr = pr->pr_linux;
 		if (lpr->pr_osname[0])
@@ -170,7 +171,7 @@ linux_get_osrelease(p)
 	register struct prison *pr;
 	register struct linux_prison *lpr;
 
-	pr = p->p_prison;
+	pr = p->p_ucred->cr_prison;
 	if (pr != NULL && pr->pr_linux != NULL) {
 		lpr = pr->pr_linux;
 		if (lpr->pr_osrelease[0])
@@ -203,7 +204,7 @@ linux_get_oss_version(p)
 	register struct prison *pr;
 	register struct linux_prison *lpr;
 
-	pr = p->p_prison;
+	pr = p->p_ucred->cr_prison;
 	if (pr != NULL && pr->pr_linux != NULL) {
 		lpr = pr->pr_linux;
 		if (lpr->pr_oss_version)
diff --git a/sys/compat/svr4/svr4_misc.c b/sys/compat/svr4/svr4_misc.c
index 680109b..3d40681 100644
--- a/sys/compat/svr4/svr4_misc.c
+++ b/sys/compat/svr4/svr4_misc.c
@@ -1299,15 +1299,6 @@ loop:
 				q->p_cred = NULL;
 			}
 
-	                /*
-			 * Destroy empty prisons
-			 */
-			if (q->p_prison && !--q->p_prison->pr_ref) {
-				if (q->p_prison->pr_linux != NULL)
-					FREE(q->p_prison->pr_linux, M_PRISON);
-				FREE(q->p_prison, M_PRISON);
-			}
-
 			/*
 			 * Remove unused arguments
 			 */