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Commit e37c1877 authored by Stephen Smalley's avatar Stephen Smalley Committed by Paul Moore
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scripts/selinux: modernize mdp 

Derived in part from a patch by Dominick Grift.

The MDP example no longer works on modern systems.  Fix it.
While we are at it, add MLS support and enable it.

NB This still does not work on systems using dbus-daemon instead of
dbus-broker because dbus-daemon does not yet gracefully handle unknown
classes/permissions.  This appears to be a deficiency in libselinux's
selinux_set_mapping() interface and underlying implementation,
which was never fully updated to deal with unknown classes/permissions
unlike the kernel.  The same problem also occurs with XSELinux.
Programs that instead use selinux_check_access() like dbus-broker
should not have this problem.

Changes to mdp:
Add support for devtmpfs, required by modern Linux distributions.
Add MLS support, with sample sensitivities, categories, and constraints.
Generate fs_use and genfscon rules based on kernel configuration.
Update list of filesystem types for fs_use and genfscon rules.
Use object_r for object contexts.

Changes to install_policy.sh:
Bail immediately on any errors.
Provide more helpful error messages when unable to find userspace tools.
Refuse to run if SELinux is already enabled.
Unconditionally move aside /etc/selinux/config and create a new one.
Build policy with -U allow so that userspace object managers do not break.
Build policy with MLS enabled by default.
Create seusers, failsafe_context, and default_contexts for use by
pam_selinux / libselinux.
Create x_contexts for the SELinux X extension.
Create virtual_domain_context and virtual_image_context for libvirtd.
Set to permissive mode rather than enforcing to permit initial autorelabel.
Update the list of filesystem types to be relabeled.
Write -F to /.autorelabel to cause a forced autorelabel on reboot.
Drop broken attempt to relabel the /dev mountpoint directory.
Signed-off-by: default avatarStephen Smalley <sds@tycho.nsa.gov>
Acked-by: default avatarDominick Grift <dominick.grift@defensec.nl>
Signed-off-by: default avatarPaul Moore <paul@paul-moore.com>
parent 9e98c678
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Inline Side-by-side
Showing with 194 additions and 63 deletions
scripts/selinux/install_policy.sh
View file @ e37c1877
#!/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
scripts/selinux/mdp/mdp.c
View file @ e37c1877
......@@ -33,6 +33,7 @@
#include <unistd.h>
#include <string.h>
#include <sys/socket.h>
#include <linux/kconfig.h>
static void usage(char *name)
{
......@@ -95,10 +96,31 @@ 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 */
......@@ -108,34 +130,127 @@ 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);
......@@ -144,8 +259,8 @@ 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;
......
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