Add a new sysctl, "security.jail.chflags_allowed", which controls the

behaviour of chflags within a jail.  If set to 0 (the default), then a
jailed root user is treated as an unprivileged user; if set to 1, then
a jailed root user is treated the same as an unjailed root user.

This is necessary to allow "make installworld" to work inside a jail,
since it attempts to manipulate the system immutable flag on certain
files.

Discussed with:	csjp, rwatson
MFC after:	2 weeks

1 files changed, 5 insertions, 0 deletions

diff --git a/sys/kern/kern_jail.c b/sys/kern/kern_jail.c
index 7a8442e..28120fd 100644
--- a/sys/kern/kern_jail.c
+++ b/sys/kern/kern_jail.c
@@ -67,6 +67,11 @@ SYSCTL_INT(_security_jail, OID_AUTO, allow_raw_sockets, CTLFLAG_RW,
     &jail_allow_raw_sockets, 0,
     "Prison root can create raw sockets");
 
+int	jail_chflags_allowed = 0;
+SYSCTL_INT(_security_jail, OID_AUTO, chflags_allowed, CTLFLAG_RW,
+    &jail_chflags_allowed, 0,
+    "Processes in jail can alter system file flags");
+
 /* allprison, lastprid, and prisoncount are protected by allprison_mtx. */
 struct	prisonlist allprison;
 struct	mtx allprison_mtx;