Add allow.mount.fdescfs jail flag.

PR:		192951
Submitted by:	ruben@verweg.com
MFC after:	3 days

4 files changed, 26 insertions, 4 deletions

diff --git a/sys/fs/fdescfs/fdesc_vfsops.c b/sys/fs/fdescfs/fdesc_vfsops.c
index cb5e3c0..d3d8ce0 100644
--- a/sys/fs/fdescfs/fdesc_vfsops.c
+++ b/sys/fs/fdescfs/fdesc_vfsops.c
@@ -42,6 +42,7 @@
 #include <sys/systm.h>
 #include <sys/filedesc.h>
 #include <sys/kernel.h>
+#include <sys/jail.h>
 #include <sys/lock.h>
 #include <sys/mutex.h>
 #include <sys/malloc.h>
@@ -78,8 +79,12 @@ fdesc_mount(struct mount *mp)
 {
 	int error = 0;
 	struct fdescmount *fmp;
+	struct thread *td = curthread;
 	struct vnode *rvp;
 
+	if (!prison_allow(td->td_ucred, PR_ALLOW_MOUNT_FDESCFS))
+		return (EPERM);
+
 	/*
 	 * Update is a no-op
 	 */
@@ -237,4 +242,4 @@ static struct vfsops fdesc_vfsops = {
 	.vfs_unmount =		fdesc_unmount,
 };
 
-VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC);
+VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC | VFCF_JAIL);
diff --git a/sys/kern/kern_jail.c b/sys/kern/kern_jail.c
index 468eaaf..269c87e 100644
--- a/sys/kern/kern_jail.c
+++ b/sys/kern/kern_jail.c
@@ -208,6 +208,7 @@ static char *pr_allow_names[] = {
 	"allow.mount.zfs",
 	"allow.mount.procfs",
 	"allow.mount.tmpfs",
+	"allow.mount.fdescfs",
 };
 const size_t pr_allow_names_size = sizeof(pr_allow_names);
 
@@ -224,6 +225,7 @@ static char *pr_allow_nonames[] = {
 	"allow.mount.nozfs",
 	"allow.mount.noprocfs",
 	"allow.mount.notmpfs",
+	"allow.mount.nofdescfs",
 };
 const size_t pr_allow_nonames_size = sizeof(pr_allow_nonames);
 
@@ -4213,6 +4215,10 @@ SYSCTL_PROC(_security_jail, OID_AUTO, mount_devfs_allowed,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
     NULL, PR_ALLOW_MOUNT_DEVFS, sysctl_jail_default_allow, "I",
     "Processes in jail can mount the devfs file system");
+SYSCTL_PROC(_security_jail, OID_AUTO, mount_fdescfs_allowed,
+    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
+    NULL, PR_ALLOW_MOUNT_FDESCFS, sysctl_jail_default_allow, "I",
+    "Processes in jail can mount the fdescfs file system");
 SYSCTL_PROC(_security_jail, OID_AUTO, mount_nullfs_allowed,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
     NULL, PR_ALLOW_MOUNT_NULLFS, sysctl_jail_default_allow, "I",
@@ -4373,6 +4379,8 @@ SYSCTL_JAIL_PARAM(_allow_mount, , CTLTYPE_INT | CTLFLAG_RW,
     "B", "Jail may mount/unmount jail-friendly file systems in general");
 SYSCTL_JAIL_PARAM(_allow_mount, devfs, CTLTYPE_INT | CTLFLAG_RW,
     "B", "Jail may mount the devfs file system");
+SYSCTL_JAIL_PARAM(_allow_mount, fdescfs, CTLTYPE_INT | CTLFLAG_RW,
+    "B", "Jail may mount the fdescfs file system");
 SYSCTL_JAIL_PARAM(_allow_mount, nullfs, CTLTYPE_INT | CTLFLAG_RW,
     "B", "Jail may mount the nullfs file system");
 SYSCTL_JAIL_PARAM(_allow_mount, procfs, CTLTYPE_INT | CTLFLAG_RW,
diff --git a/sys/sys/jail.h b/sys/sys/jail.h
index 4605f88..b1d8b01 100644
--- a/sys/sys/jail.h
+++ b/sys/sys/jail.h
@@ -226,7 +226,8 @@ struct prison_racct {
 #define	PR_ALLOW_MOUNT_ZFS		0x0200
 #define	PR_ALLOW_MOUNT_PROCFS		0x0400
 #define	PR_ALLOW_MOUNT_TMPFS		0x0800
-#define	PR_ALLOW_ALL			0x0fff
+#define	PR_ALLOW_MOUNT_FDESCFS		0x1000
+#define	PR_ALLOW_ALL			0x1fff
 
 /*
  * OSD methods
diff --git a/usr.sbin/jail/jail.8 b/usr.sbin/jail/jail.8
index 9719854..d580c25 100644
--- a/usr.sbin/jail/jail.8
+++ b/usr.sbin/jail/jail.8
@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd August 4, 2014
+.Dd January 28, 2015
 .Dt JAIL 8
 .Os
 .Sh NAME
@@ -362,7 +362,7 @@ A set of IPv6 options for the jail, the counterparts to
 and
 .Va ip4
 above.
-.It vnet
+.It Va vnet
 Create the jail with its own virtual network stack,
 with its own network interfaces, addresses, routing table, etc.
 The kernel must have been compiled with the
@@ -531,6 +531,14 @@ is set to a value lower than 2.
 The devfs ruleset should be restricted from the default by using the
 .Va devfs_ruleset
 option.
+.It Va allow.mount.fdescfs
+privileged users inside the jail will be able to mount and unmount the
+fdescfs file system.
+This permission is effective only together with
+.Va allow.mount
+and only when
+.Va enforce_statfs
+is set to a value lower than 2.
 .It Va allow.mount.nullfs
 privileged users inside the jail will be able to mount and unmount the
 nullfs file system.