Merge tag 'selinux-pr-20190507' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:
 "We've got a few SELinux patches for the v5.2 merge window, the
  highlights are below:

   - Add LSM hooks, and the SELinux implementation, for proper labeling
     of kernfs. While we are only including the SELinux implementation
     here, the rest of the LSM folks have given the hooks a thumbs-up.

   - Update the SELinux mdp (Make Dummy Policy) script to actually work
     on a modern system.

   - Disallow userspace to change the LSM credentials via
     /proc/self/attr when the task's credentials are already overridden.

     The change was made in procfs because all the LSM folks agreed this
     was the Right Thing To Do and duplicating it across each LSM was
     going to be annoying"

* tag 'selinux-pr-20190507' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  proc: prevent changes to overridden credentials
  selinux: Check address length before reading address family
  kernfs: fix xattr name handling in LSM helpers
  MAINTAINERS: update SELinux file patterns
  selinux: avoid uninitialized variable warning
  selinux: remove useless assignments
  LSM: lsm_hooks.h - fix missing colon in docstring
  selinux: Make selinux_kernfs_init_security static
  kernfs: initialize security of newly created nodes
  selinux: implement the kernfs_init_security hook
  LSM: add new hook for kernfs node initialization
  kernfs: use simple_xattrs for security attributes
  selinux: try security xattr after genfs for kernfs filesystems
  kernfs: do not alloc iattrs in kernfs_xattr_get
  kernfs: clean up struct kernfs_iattrs
  scripts/selinux: fix build
  selinux: use kernel linux/socket.h for genheaders and mdp
  scripts/selinux: modernize mdp

3 files changed, 195 insertions, 64 deletions

diff --git a/scripts/selinux/install_policy.sh b/scripts/selinux/install_policy.sh
index 0b86c47baf7d..2dccf141241d 100755
--- a/scripts/selinux/install_policy.sh
+++ b/scripts/selinux/install_policy.sh
@@ -1,30 +1,61 @@
 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
+set -e
 if [ `id -u` -ne 0 ]; then
 	echo "$0: must be root to install the selinux policy"
 	exit 1
 fi
+
 SF=`which setfiles`
 if [ $? -eq 1 ]; then
-	if [ -f /sbin/setfiles ]; then
-		SF="/usr/setfiles"
-	else
-		echo "no selinux tools installed: setfiles"
-		exit 1
-	fi
+	echo "Could not find setfiles"
+	echo "Do you have policycoreutils installed?"
+	exit 1
 fi
 
-cd mdp
-
 CP=`which checkpolicy`
+if [ $? -eq 1 ]; then
+	echo "Could not find checkpolicy"
+	echo "Do you have checkpolicy installed?"
+	exit 1
+fi
 VERS=`$CP -V | awk '{print $1}'`
 
-./mdp policy.conf file_contexts
-$CP -o policy.$VERS policy.conf
+ENABLED=`which selinuxenabled`
+if [ $? -eq 1 ]; then
+	echo "Could not find selinuxenabled"
+	echo "Do you have libselinux-utils installed?"
+	exit 1
+fi
+
+if selinuxenabled; then
+    echo "SELinux is already enabled"
+    echo "This prevents safely relabeling all files."
+    echo "Boot with selinux=0 on the kernel command-line or"
+    echo "SELINUX=disabled in /etc/selinux/config."
+    exit 1
+fi
+
+cd mdp
+./mdp -m policy.conf file_contexts
+$CP -U allow -M -o policy.$VERS policy.conf
 
 mkdir -p /etc/selinux/dummy/policy
 mkdir -p /etc/selinux/dummy/contexts/files
 
+echo "__default__:user_u:s0" > /etc/selinux/dummy/seusers
+echo "base_r:base_t:s0" > /etc/selinux/dummy/contexts/failsafe_context
+echo "base_r:base_t:s0 base_r:base_t:s0" > /etc/selinux/dummy/default_contexts
+cat > /etc/selinux/dummy/contexts/x_contexts <<EOF
+client * user_u:base_r:base_t:s0
+property * user_u:object_r:base_t:s0
+extension * user_u:object_r:base_t:s0
+selection * user_u:object_r:base_t:s0
+event * user_u:object_r:base_t:s0
+EOF
+touch /etc/selinux/dummy/contexts/virtual_domain_context
+touch /etc/selinux/dummy/contexts/virtual_image_context
+
 cp file_contexts /etc/selinux/dummy/contexts/files
 cp dbus_contexts /etc/selinux/dummy/contexts
 cp policy.$VERS /etc/selinux/dummy/policy
@@ -33,37 +64,22 @@ FC_FILE=/etc/selinux/dummy/contexts/files/file_contexts
 if [ ! -d /etc/selinux ]; then
 	mkdir -p /etc/selinux
 fi
-if [ ! -f /etc/selinux/config ]; then
-	cat > /etc/selinux/config << EOF
-SELINUX=enforcing
+if [ -f /etc/selinux/config ]; then
+    echo "/etc/selinux/config exists, moving to /etc/selinux/config.bak."
+    mv /etc/selinux/config /etc/selinux/config.bak
+fi
+echo "Creating new /etc/selinux/config for dummy policy."
+cat > /etc/selinux/config << EOF
+SELINUX=permissive
 SELINUXTYPE=dummy
 EOF
-else
-	TYPE=`cat /etc/selinux/config | grep "^SELINUXTYPE" | tail -1 | awk -F= '{ print $2 '}`
-	if [ "eq$TYPE" != "eqdummy" ]; then
-		selinuxenabled
-		if [ $? -eq 0 ]; then
-			echo "SELinux already enabled with a non-dummy policy."
-			echo "Exiting.  Please install policy by hand if that"
-			echo "is what you REALLY want."
-			exit 1
-		fi
-		mv /etc/selinux/config /etc/selinux/config.mdpbak
-		grep -v "^SELINUXTYPE" /etc/selinux/config.mdpbak >> /etc/selinux/config
-		echo "SELINUXTYPE=dummy" >> /etc/selinux/config
-	fi
-fi
 
 cd /etc/selinux/dummy/contexts/files
-$SF file_contexts /
+$SF -F file_contexts /
 
-mounts=`cat /proc/$$/mounts | egrep "ext2|ext3|xfs|jfs|ext4|ext4dev|gfs2" | awk '{ print $2 '}`
-$SF file_contexts $mounts
+mounts=`cat /proc/$$/mounts | \
+	egrep "ext[234]|jfs|xfs|reiserfs|jffs2|gfs2|btrfs|f2fs|ocfs2" | \
+	awk '{ print $2 '}`
+$SF -F file_contexts $mounts
 
-
-dodev=`cat /proc/$$/mounts | grep "/dev "`
-if [ "eq$dodev" != "eq" ]; then
-	mount --move /dev /mnt
-	$SF file_contexts /dev
-	mount --move /mnt /dev
-fi
+echo "-F" > /.autorelabel
diff --git a/scripts/selinux/mdp/Makefile b/scripts/selinux/mdp/Makefile
index e9c92db7e2a3..8a1269a9d0ba 100644
--- a/scripts/selinux/mdp/Makefile
+++ b/scripts/selinux/mdp/Makefile
@@ -2,7 +2,7 @@
 hostprogs-y	:= mdp
 HOST_EXTRACFLAGS += \
 	-I$(srctree)/include/uapi -I$(srctree)/include \
-	-I$(srctree)/security/selinux/include
+	-I$(srctree)/security/selinux/include -I$(objtree)/include
 
 always		:= $(hostprogs-y)
 clean-files	:= policy.* file_contexts
diff --git a/scripts/selinux/mdp/mdp.c b/scripts/selinux/mdp/mdp.c
index 6d51b74bc679..18fd6143888b 100644
--- a/scripts/selinux/mdp/mdp.c
+++ b/scripts/selinux/mdp/mdp.c
@@ -32,6 +32,7 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include <string.h>
+#include <linux/kconfig.h>
 
 static void usage(char *name)
 {
@@ -94,10 +95,31 @@ int main(int argc, char *argv[])
 	}
 	fprintf(fout, "\n");
 
-	/* NOW PRINT OUT MLS STUFF */
+	/* print out mls declarations and constraints */
 	if (mls) {
-		printf("MLS not yet implemented\n");
-		exit(1);
+		fprintf(fout, "sensitivity s0;\n");
+		fprintf(fout, "sensitivity s1;\n");
+		fprintf(fout, "dominance { s0 s1 }\n");
+		fprintf(fout, "category c0;\n");
+		fprintf(fout, "category c1;\n");
+		fprintf(fout, "level s0:c0.c1;\n");
+		fprintf(fout, "level s1:c0.c1;\n");
+#define SYSTEMLOW "s0"
+#define SYSTEMHIGH "s1:c0.c1"
+		for (i = 0; secclass_map[i].name; i++) {
+			struct security_class_mapping *map = &secclass_map[i];
+
+			fprintf(fout, "mlsconstrain %s {\n", map->name);
+			for (j = 0; map->perms[j]; j++)
+				fprintf(fout, "\t%s\n", map->perms[j]);
+			/*
+			 * This requires all subjects and objects to be
+			 * single-level (l2 eq h2), and that the subject
+			 * level dominate the object level (h1 dom h2)
+			 * in order to have any permissions to it.
+			 */
+			fprintf(fout, "} (l2 eq h2 and h1 dom h2);\n\n");
+		}
 	}
 
 	/* types, roles, and allows */
@@ -107,34 +129,127 @@ int main(int argc, char *argv[])
 	for (i = 0; secclass_map[i].name; i++)
 		fprintf(fout, "allow base_t base_t:%s *;\n",
 			secclass_map[i].name);
-	fprintf(fout, "user user_u roles { base_r };\n");
-	fprintf(fout, "\n");
+	fprintf(fout, "user user_u roles { base_r }");
+	if (mls)
+		fprintf(fout, " level %s range %s - %s", SYSTEMLOW,
+			SYSTEMLOW, SYSTEMHIGH);
+	fprintf(fout, ";\n");
+
+#define SUBJUSERROLETYPE "user_u:base_r:base_t"
+#define OBJUSERROLETYPE "user_u:object_r:base_t"
 
 	/* default sids */
 	for (i = 1; i < initial_sid_to_string_len; i++)
-		fprintf(fout, "sid %s user_u:base_r:base_t\n", initial_sid_to_string[i]);
+		fprintf(fout, "sid %s " SUBJUSERROLETYPE "%s\n",
+			initial_sid_to_string[i], mls ? ":" SYSTEMLOW : "");
 	fprintf(fout, "\n");
 
-	fprintf(fout, "fs_use_xattr ext2 user_u:base_r:base_t;\n");
-	fprintf(fout, "fs_use_xattr ext3 user_u:base_r:base_t;\n");
-	fprintf(fout, "fs_use_xattr ext4 user_u:base_r:base_t;\n");
-	fprintf(fout, "fs_use_xattr jfs user_u:base_r:base_t;\n");
-	fprintf(fout, "fs_use_xattr xfs user_u:base_r:base_t;\n");
-	fprintf(fout, "fs_use_xattr reiserfs user_u:base_r:base_t;\n");
-	fprintf(fout, "fs_use_xattr jffs2 user_u:base_r:base_t;\n");
-	fprintf(fout, "fs_use_xattr gfs2 user_u:base_r:base_t;\n");
+#define FS_USE(behavior, fstype)			    \
+	fprintf(fout, "fs_use_%s %s " OBJUSERROLETYPE "%s;\n", \
+		behavior, fstype, mls ? ":" SYSTEMLOW : "")
+
+	/*
+	 * Filesystems whose inode labels can be fetched via getxattr.
+	 */
+#ifdef CONFIG_EXT2_FS_SECURITY
+	FS_USE("xattr", "ext2");
+#endif
+#ifdef CONFIG_EXT4_FS_SECURITY
+#ifdef CONFIG_EXT4_USE_FOR_EXT2
+	FS_USE("xattr", "ext2");
+#endif
+	FS_USE("xattr", "ext3");
+	FS_USE("xattr", "ext4");
+#endif
+#ifdef CONFIG_JFS_SECURITY
+	FS_USE("xattr", "jfs");
+#endif
+#ifdef CONFIG_REISERFS_FS_SECURITY
+	FS_USE("xattr", "reiserfs");
+#endif
+#ifdef CONFIG_JFFS2_FS_SECURITY
+	FS_USE("xattr", "jffs2");
+#endif
+#ifdef CONFIG_XFS_FS
+	FS_USE("xattr", "xfs");
+#endif
+#ifdef CONFIG_GFS2_FS
+	FS_USE("xattr", "gfs2");
+#endif
+#ifdef CONFIG_BTRFS_FS
+	FS_USE("xattr", "btrfs");
+#endif
+#ifdef CONFIG_F2FS_FS_SECURITY
+	FS_USE("xattr", "f2fs");
+#endif
+#ifdef CONFIG_OCFS2_FS
+	FS_USE("xattr", "ocsfs2");
+#endif
+#ifdef CONFIG_OVERLAY_FS
+	FS_USE("xattr", "overlay");
+#endif
+#ifdef CONFIG_SQUASHFS_XATTR
+	FS_USE("xattr", "squashfs");
+#endif
+
+	/*
+	 * Filesystems whose inodes are labeled from allocating task.
+	 */
+	FS_USE("task", "pipefs");
+	FS_USE("task", "sockfs");
 
-	fprintf(fout, "fs_use_task eventpollfs user_u:base_r:base_t;\n");
-	fprintf(fout, "fs_use_task pipefs user_u:base_r:base_t;\n");
-	fprintf(fout, "fs_use_task sockfs user_u:base_r:base_t;\n");
+	/*
+	 * Filesystems whose inode labels are computed from both
+	 * the allocating task and the superblock label.
+	 */
+#ifdef CONFIG_UNIX98_PTYS
+	FS_USE("trans", "devpts");
+#endif
+#ifdef CONFIG_HUGETLBFS
+	FS_USE("trans", "hugetlbfs");
+#endif
+#ifdef CONFIG_TMPFS
+	FS_USE("trans", "tmpfs");
+#endif
+#ifdef CONFIG_DEVTMPFS
+	FS_USE("trans", "devtmpfs");
+#endif
+#ifdef CONFIG_POSIX_MQUEUE
+	FS_USE("trans", "mqueue");
+#endif
 
-	fprintf(fout, "fs_use_trans mqueue user_u:base_r:base_t;\n");
-	fprintf(fout, "fs_use_trans devpts user_u:base_r:base_t;\n");
-	fprintf(fout, "fs_use_trans hugetlbfs user_u:base_r:base_t;\n");
-	fprintf(fout, "fs_use_trans tmpfs user_u:base_r:base_t;\n");
-	fprintf(fout, "fs_use_trans shm user_u:base_r:base_t;\n");
+#define GENFSCON(fstype, prefix)			     \
+	fprintf(fout, "genfscon %s %s " OBJUSERROLETYPE "%s\n", \
+		fstype, prefix, mls ? ":" SYSTEMLOW : "")
 
-	fprintf(fout, "genfscon proc / user_u:base_r:base_t\n");
+	/*
+	 * Filesystems whose inodes are labeled from path prefix match
+	 * relative to the filesystem root.  Depending on the filesystem,
+	 * only a single label for all inodes may be supported.  Here
+	 * we list the filesystem types for which per-file labeling is
+	 * supported using genfscon; any other filesystem type can also
+	 * be added by only with a single entry for all of its inodes.
+	 */
+#ifdef CONFIG_PROC_FS
+	GENFSCON("proc", "/");
+#endif
+#ifdef CONFIG_SECURITY_SELINUX
+	GENFSCON("selinuxfs", "/");
+#endif
+#ifdef CONFIG_SYSFS
+	GENFSCON("sysfs", "/");
+#endif
+#ifdef CONFIG_DEBUG_FS
+	GENFSCON("debugfs", "/");
+#endif
+#ifdef CONFIG_TRACING
+	GENFSCON("tracefs", "/");
+#endif
+#ifdef CONFIG_PSTORE
+	GENFSCON("pstore", "/");
+#endif
+	GENFSCON("cgroup", "/");
+	GENFSCON("cgroup2", "/");
 
 	fclose(fout);
 
@@ -143,8 +258,8 @@ int main(int argc, char *argv[])
 		printf("Wrote policy, but cannot open %s for writing\n", ctxout);
 		usage(argv[0]);
 	}
-	fprintf(fout, "/ user_u:base_r:base_t\n");
-	fprintf(fout, "/.* user_u:base_r:base_t\n");
+	fprintf(fout, "/ " OBJUSERROLETYPE "%s\n", mls ? ":" SYSTEMLOW : "");
+	fprintf(fout, "/.* " OBJUSERROLETYPE "%s\n", mls ? ":" SYSTEMLOW : "");
 	fclose(fout);
 
 	return 0;