diff mbox series

[v3] scripts/selinux: modernize mdp

Message ID 20190220153408.1857-1-dominick.grift@defensec.nl (mailing list archive)
State Superseded
Headers show
Series [v3] scripts/selinux: modernize mdp | expand

Commit Message

Dominick Grift Feb. 20, 2019, 3:34 p.m. UTC
The MDP example no longer works on modern systems.

Add support for devtmpfs. This is required by login programs to relabel terminals.
Compile the policy with deny_unknown allow status to anticipate user space object managers in core components such as systemd.
Add default seusers mapping and failsafe context for the SELinux PAM module.

V2:
Fix existing file test for setfiles.
Add a file test for checkpolicy similar to the test for setfiles for consistency.
Execute setfiles with -F to ensure that customizables are relabeled as well in scenarios where filesystems are labeled but where SELinux is disabled.

V3: Fixes file test that was introduced in V2.

Signed-off-by: Dominick Grift <dominick.grift@defensec.nl>
---
 scripts/selinux/install_policy.sh | 21 ++++++++++++++++-----
 scripts/selinux/mdp/mdp.c         |  1 +
 2 files changed, 17 insertions(+), 5 deletions(-)

Comments

Stephen Smalley Feb. 20, 2019, 7:34 p.m. UTC | #1
On Wed, Feb 20, 2019 at 10:34 AM Dominick Grift
<dominick.grift@defensec.nl> wrote:
>
> The MDP example no longer works on modern systems.
>
> Add support for devtmpfs. This is required by login programs to relabel terminals.
> Compile the policy with deny_unknown allow status to anticipate user space object managers in core components such as systemd.
> Add default seusers mapping and failsafe context for the SELinux PAM module.
>
> V2:
> Fix existing file test for setfiles.
> Add a file test for checkpolicy similar to the test for setfiles for consistency.
> Execute setfiles with -F to ensure that customizables are relabeled as well in scenarios where filesystems are labeled but where SELinux is disabled.
>
> V3: Fixes file test that was introduced in V2.
>
> Signed-off-by: Dominick Grift <dominick.grift@defensec.nl>
> ---
>  scripts/selinux/install_policy.sh | 21 ++++++++++++++++-----
>  scripts/selinux/mdp/mdp.c         |  1 +
>  2 files changed, 17 insertions(+), 5 deletions(-)
>
> diff --git a/scripts/selinux/install_policy.sh b/scripts/selinux/install_policy.sh
> index 0b86c47baf7d..e32f333f14cc 100755
> --- a/scripts/selinux/install_policy.sh
> +++ b/scripts/selinux/install_policy.sh
> @@ -6,7 +6,7 @@ if [ `id -u` -ne 0 ]; then
>  fi
>  SF=`which setfiles`
>  if [ $? -eq 1 ]; then
> -       if [ -f /sbin/setfiles ]; then
> +       if [ -f /usr/setfiles ]; then
>                 SF="/usr/setfiles"

I don't believe we've ever installed setfiles anywhere other than
/sbin/setfile or /usr/sbin/setfiles so no other locations should be
used.  Maybe just drop the inner if statement entirely.

>         else
>                 echo "no selinux tools installed: setfiles"
> @@ -17,14 +17,25 @@ fi
>  cd mdp
>
>  CP=`which checkpolicy`
> +if [ $? -eq 1 ]; then
> +       if [ -f /usr/checkpolicy ]; then
> +               CP="/usr/checkpolicy"

Similarly for /usr/bin/checkpolicy or /bin/checkpolicy.

> +       else
> +               echo "no selinux tools installed: checkpolicy"
> +               exit 1
> +       fi
> +fi
>  VERS=`$CP -V | awk '{print $1}'`
>
>  ./mdp policy.conf file_contexts
> -$CP -o policy.$VERS policy.conf
> +$CP -U allow -o policy.$VERS policy.conf
>
>  mkdir -p /etc/selinux/dummy/policy
>  mkdir -p /etc/selinux/dummy/contexts/files
>
> +echo "__default__:user_u" > /etc/selinux/dummy/seusers
> +echo "base_r:base_t" > /etc/selinux/dummy/contexts/failsafe_context
> +
>  cp file_contexts /etc/selinux/dummy/contexts/files
>  cp dbus_contexts /etc/selinux/dummy/contexts
>  cp policy.$VERS /etc/selinux/dummy/policy
> @@ -55,15 +66,15 @@ else
>  fi
>
>  cd /etc/selinux/dummy/contexts/files
> -$SF file_contexts /
> +$SF -F file_contexts /
>
>  mounts=`cat /proc/$$/mounts | egrep "ext2|ext3|xfs|jfs|ext4|ext4dev|gfs2" | awk '{ print $2 '}`
> -$SF file_contexts $mounts
> +$SF -F file_contexts $mounts
>
>
>  dodev=`cat /proc/$$/mounts | grep "/dev "`
>  if [ "eq$dodev" != "eq" ]; then
>         mount --move /dev /mnt

I recall seeing errors from mount when running this script about
invalid usage of mount --move?

> -       $SF file_contexts /dev
> +       $SF -F file_contexts /dev
>         mount --move /mnt /dev
>  fi
> diff --git a/scripts/selinux/mdp/mdp.c b/scripts/selinux/mdp/mdp.c
> index 073fe7537f6c..cf06d5694cbc 100644
> --- a/scripts/selinux/mdp/mdp.c
> +++ b/scripts/selinux/mdp/mdp.c
> @@ -131,6 +131,7 @@ int main(int argc, char *argv[])
>
>         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 devtmpfs user_u:base_r:base_t;\n");

This will conflict with my patch but probably your patch should be
applied first since it fixes current usage of mdp, and then mine can
be re-based and introduce the MLS support (which hopefully can now be
tested on Fedora). Ideally we'd add fs_use* and genfscon statements
for all filesystems supported by the kernel but that can come later.

>         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");
> --
> 2.21.0.rc1
>
Dominick Grift Feb. 20, 2019, 7:36 p.m. UTC | #2
On Wed, Feb 20, 2019 at 02:34:16PM -0500, Stephen Smalley wrote:
> On Wed, Feb 20, 2019 at 10:34 AM Dominick Grift
> <dominick.grift@defensec.nl> wrote:
> >
> > The MDP example no longer works on modern systems.
> >
> > Add support for devtmpfs. This is required by login programs to relabel terminals.
> > Compile the policy with deny_unknown allow status to anticipate user space object managers in core components such as systemd.
> > Add default seusers mapping and failsafe context for the SELinux PAM module.
> >
> > V2:
> > Fix existing file test for setfiles.
> > Add a file test for checkpolicy similar to the test for setfiles for consistency.
> > Execute setfiles with -F to ensure that customizables are relabeled as well in scenarios where filesystems are labeled but where SELinux is disabled.
> >
> > V3: Fixes file test that was introduced in V2.
> >
> > Signed-off-by: Dominick Grift <dominick.grift@defensec.nl>
> > ---
> >  scripts/selinux/install_policy.sh | 21 ++++++++++++++++-----
> >  scripts/selinux/mdp/mdp.c         |  1 +
> >  2 files changed, 17 insertions(+), 5 deletions(-)
> >
> > diff --git a/scripts/selinux/install_policy.sh b/scripts/selinux/install_policy.sh
> > index 0b86c47baf7d..e32f333f14cc 100755
> > --- a/scripts/selinux/install_policy.sh
> > +++ b/scripts/selinux/install_policy.sh
> > @@ -6,7 +6,7 @@ if [ `id -u` -ne 0 ]; then
> >  fi
> >  SF=`which setfiles`
> >  if [ $? -eq 1 ]; then
> > -       if [ -f /sbin/setfiles ]; then
> > +       if [ -f /usr/setfiles ]; then
> >                 SF="/usr/setfiles"
> 
> I don't believe we've ever installed setfiles anywhere other than
> /sbin/setfile or /usr/sbin/setfiles so no other locations should be
> used.  Maybe just drop the inner if statement entirely.

I agree

> 
> >         else
> >                 echo "no selinux tools installed: setfiles"
> > @@ -17,14 +17,25 @@ fi
> >  cd mdp
> >
> >  CP=`which checkpolicy`
> > +if [ $? -eq 1 ]; then
> > +       if [ -f /usr/checkpolicy ]; then
> > +               CP="/usr/checkpolicy"
> 
> Similarly for /usr/bin/checkpolicy or /bin/checkpolicy.
> 
> > +       else
> > +               echo "no selinux tools installed: checkpolicy"
> > +               exit 1
> > +       fi
> > +fi
> >  VERS=`$CP -V | awk '{print $1}'`
> >
> >  ./mdp policy.conf file_contexts
> > -$CP -o policy.$VERS policy.conf
> > +$CP -U allow -o policy.$VERS policy.conf
> >
> >  mkdir -p /etc/selinux/dummy/policy
> >  mkdir -p /etc/selinux/dummy/contexts/files
> >
> > +echo "__default__:user_u" > /etc/selinux/dummy/seusers
> > +echo "base_r:base_t" > /etc/selinux/dummy/contexts/failsafe_context
> > +
> >  cp file_contexts /etc/selinux/dummy/contexts/files
> >  cp dbus_contexts /etc/selinux/dummy/contexts
> >  cp policy.$VERS /etc/selinux/dummy/policy
> > @@ -55,15 +66,15 @@ else
> >  fi
> >
> >  cd /etc/selinux/dummy/contexts/files
> > -$SF file_contexts /
> > +$SF -F file_contexts /
> >
> >  mounts=`cat /proc/$$/mounts | egrep "ext2|ext3|xfs|jfs|ext4|ext4dev|gfs2" | awk '{ print $2 '}`
> > -$SF file_contexts $mounts
> > +$SF -F file_contexts $mounts
> >
> >
> >  dodev=`cat /proc/$$/mounts | grep "/dev "`
> >  if [ "eq$dodev" != "eq" ]; then
> >         mount --move /dev /mnt
> 
> I recall seeing errors from mount when running this script about
> invalid usage of mount --move?
> 
> > -       $SF file_contexts /dev
> > +       $SF -F file_contexts /dev
> >         mount --move /mnt /dev
> >  fi
> > diff --git a/scripts/selinux/mdp/mdp.c b/scripts/selinux/mdp/mdp.c
> > index 073fe7537f6c..cf06d5694cbc 100644
> > --- a/scripts/selinux/mdp/mdp.c
> > +++ b/scripts/selinux/mdp/mdp.c
> > @@ -131,6 +131,7 @@ int main(int argc, char *argv[])
> >
> >         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 devtmpfs user_u:base_r:base_t;\n");
> 
> This will conflict with my patch but probably your patch should be
> applied first since it fixes current usage of mdp, and then mine can
> be re-based and introduce the MLS support (which hopefully can now be
> tested on Fedora). Ideally we'd add fs_use* and genfscon statements
> for all filesystems supported by the kernel but that can come later.
> 
> >         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");
> > --
> > 2.21.0.rc1
> >
Dominick Grift Feb. 20, 2019, 8:25 p.m. UTC | #3
On Wed, Feb 20, 2019 at 02:34:16PM -0500, Stephen Smalley wrote:
> On Wed, Feb 20, 2019 at 10:34 AM Dominick Grift
> <dominick.grift@defensec.nl> wrote:
> >
> > The MDP example no longer works on modern systems.
> >
> > Add support for devtmpfs. This is required by login programs to relabel terminals.
> > Compile the policy with deny_unknown allow status to anticipate user space object managers in core components such as systemd.
> > Add default seusers mapping and failsafe context for the SELinux PAM module.
> >
> > V2:
> > Fix existing file test for setfiles.
> > Add a file test for checkpolicy similar to the test for setfiles for consistency.
> > Execute setfiles with -F to ensure that customizables are relabeled as well in scenarios where filesystems are labeled but where SELinux is disabled.
> >
> > V3: Fixes file test that was introduced in V2.
> >
> > Signed-off-by: Dominick Grift <dominick.grift@defensec.nl>
> > ---
> >  scripts/selinux/install_policy.sh | 21 ++++++++++++++++-----
> >  scripts/selinux/mdp/mdp.c         |  1 +
> >  2 files changed, 17 insertions(+), 5 deletions(-)
> >
> > diff --git a/scripts/selinux/install_policy.sh b/scripts/selinux/install_policy.sh
> > index 0b86c47baf7d..e32f333f14cc 100755
> > --- a/scripts/selinux/install_policy.sh
> > +++ b/scripts/selinux/install_policy.sh
> > @@ -6,7 +6,7 @@ if [ `id -u` -ne 0 ]; then
> >  fi
> >  SF=`which setfiles`
> >  if [ $? -eq 1 ]; then
> > -       if [ -f /sbin/setfiles ]; then
> > +       if [ -f /usr/setfiles ]; then
> >                 SF="/usr/setfiles"
> 
> I don't believe we've ever installed setfiles anywhere other than
> /sbin/setfile or /usr/sbin/setfiles so no other locations should be
> used.  Maybe just drop the inner if statement entirely.
> 
> >         else
> >                 echo "no selinux tools installed: setfiles"
> > @@ -17,14 +17,25 @@ fi
> >  cd mdp
> >
> >  CP=`which checkpolicy`
> > +if [ $? -eq 1 ]; then
> > +       if [ -f /usr/checkpolicy ]; then
> > +               CP="/usr/checkpolicy"
> 
> Similarly for /usr/bin/checkpolicy or /bin/checkpolicy.
> 
> > +       else
> > +               echo "no selinux tools installed: checkpolicy"
> > +               exit 1
> > +       fi
> > +fi
> >  VERS=`$CP -V | awk '{print $1}'`
> >
> >  ./mdp policy.conf file_contexts
> > -$CP -o policy.$VERS policy.conf
> > +$CP -U allow -o policy.$VERS policy.conf
> >
> >  mkdir -p /etc/selinux/dummy/policy
> >  mkdir -p /etc/selinux/dummy/contexts/files
> >
> > +echo "__default__:user_u" > /etc/selinux/dummy/seusers
> > +echo "base_r:base_t" > /etc/selinux/dummy/contexts/failsafe_context
> > +
> >  cp file_contexts /etc/selinux/dummy/contexts/files
> >  cp dbus_contexts /etc/selinux/dummy/contexts
> >  cp policy.$VERS /etc/selinux/dummy/policy
> > @@ -55,15 +66,15 @@ else
> >  fi
> >
> >  cd /etc/selinux/dummy/contexts/files
> > -$SF file_contexts /
> > +$SF -F file_contexts /
> >
> >  mounts=`cat /proc/$$/mounts | egrep "ext2|ext3|xfs|jfs|ext4|ext4dev|gfs2" | awk '{ print $2 '}`
> > -$SF file_contexts $mounts
> > +$SF -F file_contexts $mounts
> >
> >
> >  dodev=`cat /proc/$$/mounts | grep "/dev "`
> >  if [ "eq$dodev" != "eq" ]; then
> >         mount --move /dev /mnt
> 
> I recall seeing errors from mount when running this script about
> invalid usage of mount --move?

Yes but we may want this for (backwards) compatibility? I suspect that this might work in some scenario's (just not ours)

> 
> > -       $SF file_contexts /dev
> > +       $SF -F file_contexts /dev
> >         mount --move /mnt /dev
> >  fi
> > diff --git a/scripts/selinux/mdp/mdp.c b/scripts/selinux/mdp/mdp.c
> > index 073fe7537f6c..cf06d5694cbc 100644
> > --- a/scripts/selinux/mdp/mdp.c
> > +++ b/scripts/selinux/mdp/mdp.c
> > @@ -131,6 +131,7 @@ int main(int argc, char *argv[])
> >
> >         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 devtmpfs user_u:base_r:base_t;\n");
> 
> This will conflict with my patch but probably your patch should be
> applied first since it fixes current usage of mdp, and then mine can
> be re-based and introduce the MLS support (which hopefully can now be
> tested on Fedora). Ideally we'd add fs_use* and genfscon statements
> for all filesystems supported by the kernel but that can come later.

Probably yes, but you can also just take my changes and add them to your patch.

BTW: we also might want to use object_r instead of base_r for object contexts for consistency?

> 
> >         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");
> > --
> > 2.21.0.rc1
> >
diff mbox series

Patch

diff --git a/scripts/selinux/install_policy.sh b/scripts/selinux/install_policy.sh
index 0b86c47baf7d..e32f333f14cc 100755
--- a/scripts/selinux/install_policy.sh
+++ b/scripts/selinux/install_policy.sh
@@ -6,7 +6,7 @@  if [ `id -u` -ne 0 ]; then
 fi
 SF=`which setfiles`
 if [ $? -eq 1 ]; then
-	if [ -f /sbin/setfiles ]; then
+	if [ -f /usr/setfiles ]; then
 		SF="/usr/setfiles"
 	else
 		echo "no selinux tools installed: setfiles"
@@ -17,14 +17,25 @@  fi
 cd mdp
 
 CP=`which checkpolicy`
+if [ $? -eq 1 ]; then
+	if [ -f /usr/checkpolicy ]; then
+		CP="/usr/checkpolicy"
+	else
+		echo "no selinux tools installed: checkpolicy"
+		exit 1
+	fi
+fi
 VERS=`$CP -V | awk '{print $1}'`
 
 ./mdp policy.conf file_contexts
-$CP -o policy.$VERS policy.conf
+$CP -U allow -o policy.$VERS policy.conf
 
 mkdir -p /etc/selinux/dummy/policy
 mkdir -p /etc/selinux/dummy/contexts/files
 
+echo "__default__:user_u" > /etc/selinux/dummy/seusers
+echo "base_r:base_t" > /etc/selinux/dummy/contexts/failsafe_context
+
 cp file_contexts /etc/selinux/dummy/contexts/files
 cp dbus_contexts /etc/selinux/dummy/contexts
 cp policy.$VERS /etc/selinux/dummy/policy
@@ -55,15 +66,15 @@  else
 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 $mounts
+$SF -F file_contexts $mounts
 
 
 dodev=`cat /proc/$$/mounts | grep "/dev "`
 if [ "eq$dodev" != "eq" ]; then
 	mount --move /dev /mnt
-	$SF file_contexts /dev
+	$SF -F file_contexts /dev
 	mount --move /mnt /dev
 fi
diff --git a/scripts/selinux/mdp/mdp.c b/scripts/selinux/mdp/mdp.c
index 073fe7537f6c..cf06d5694cbc 100644
--- a/scripts/selinux/mdp/mdp.c
+++ b/scripts/selinux/mdp/mdp.c
@@ -131,6 +131,7 @@  int main(int argc, char *argv[])
 
 	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 devtmpfs 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");