apparmor: add mount mediation

Add basic mount mediation. That allows controlling based on basic
mount parameters. It does not include special mount parameters for
apparmor, super block labeling, or any triggers for apparmor namespace
parameter modifications on pivot root.

default userspace policy rules have the form of
  MOUNT RULE = ( MOUNT | REMOUNT | UMOUNT )

  MOUNT = [ QUALIFIERS ] 'mount' [ MOUNT CONDITIONS ] [ SOURCE FILEGLOB ]
          [ '->' MOUNTPOINT FILEGLOB ]

  REMOUNT = [ QUALIFIERS ] 'remount' [ MOUNT CONDITIONS ]
            MOUNTPOINT FILEGLOB

  UMOUNT = [ QUALIFIERS ] 'umount' [ MOUNT CONDITIONS ] MOUNTPOINT FILEGLOB

  MOUNT CONDITIONS = [ ( 'fstype' | 'vfstype' ) ( '=' | 'in' )
                       MOUNT FSTYPE EXPRESSION ]
		       [ 'options' ( '=' | 'in' ) MOUNT FLAGS EXPRESSION ]

  MOUNT FSTYPE EXPRESSION = ( MOUNT FSTYPE LIST | MOUNT EXPRESSION )

  MOUNT FSTYPE LIST = Comma separated list of valid filesystem and
                      virtual filesystem types (eg ext4, debugfs, etc)

  MOUNT FLAGS EXPRESSION = ( MOUNT FLAGS LIST | MOUNT EXPRESSION )

  MOUNT FLAGS LIST = Comma separated list of MOUNT FLAGS.

  MOUNT FLAGS = ( 'ro' | 'rw' | 'nosuid' | 'suid' | 'nodev' | 'dev' |
                  'noexec' | 'exec' | 'sync' | 'async' | 'remount' |
		  'mand' | 'nomand' | 'dirsync' | 'noatime' | 'atime' |
		  'nodiratime' | 'diratime' | 'bind' | 'rbind' | 'move' |
		  'verbose' | 'silent' | 'loud' | 'acl' | 'noacl' |
		  'unbindable' | 'runbindable' | 'private' | 'rprivate' |
		  'slave' | 'rslave' | 'shared' | 'rshared' |
		  'relatime' | 'norelatime' | 'iversion' | 'noiversion' |
		  'strictatime' | 'nouser' | 'user' )

  MOUNT EXPRESSION = ( ALPHANUMERIC | AARE ) ...

  PIVOT ROOT RULE = [ QUALIFIERS ] pivot_root [ oldroot=OLD PUT FILEGLOB ]
                    [ NEW ROOT FILEGLOB ]

  SOURCE FILEGLOB = FILEGLOB

  MOUNTPOINT FILEGLOB = FILEGLOB

eg.
  mount,
  mount /dev/foo,
  mount options=ro /dev/foo -> /mnt/,
  mount options in (ro,atime) /dev/foo -> /mnt/,
  mount options=ro options=atime,

Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Seth Arnold <seth.arnold@canonical.com>

9 files changed, 841 insertions, 4 deletions

diff --git a/security/apparmor/Makefile b/security/apparmor/Makefile
index a16b195274de..81a34426d024 100644
--- a/security/apparmor/Makefile
+++ b/security/apparmor/Makefile
@@ -4,7 +4,7 @@ obj-$(CONFIG_SECURITY_APPARMOR) += apparmor.o
 
 apparmor-y := apparmorfs.o audit.o capability.o context.o ipc.o lib.o match.o \
               path.o domain.o policy.o policy_unpack.o procattr.o lsm.o \
-              resource.o secid.o file.o policy_ns.o label.o
+              resource.o secid.o file.o policy_ns.o label.o mount.o
 apparmor-$(CONFIG_SECURITY_APPARMOR_HASH) += crypto.o
 
 clean-files := capability_names.h rlim_names.h
diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index a5f9e1aa51f7..8fa6c898c44b 100644
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -2159,9 +2159,14 @@ static struct aa_sfs_entry aa_sfs_entry_policy[] = {
         { }
 };
 
+static struct aa_sfs_entry aa_sfs_entry_mount[] = {
+        AA_SFS_FILE_STRING("mask", "mount umount pivot_root"),
+        { }
+};
+
 static struct aa_sfs_entry aa_sfs_entry_ns[] = {
         AA_SFS_FILE_BOOLEAN("profile",          1),
-        AA_SFS_FILE_BOOLEAN("pivot_root",       1),
+        AA_SFS_FILE_BOOLEAN("pivot_root",       0),
         { }
 };
 
@@ -2180,6 +2185,7 @@ static struct aa_sfs_entry aa_sfs_entry_features[] = {
         AA_SFS_DIR("policy",                    aa_sfs_entry_policy),
         AA_SFS_DIR("domain",                    aa_sfs_entry_domain),
         AA_SFS_DIR("file",                      aa_sfs_entry_file),
+        AA_SFS_DIR("mount",                     aa_sfs_entry_mount),
         AA_SFS_DIR("namespaces",                aa_sfs_entry_ns),
         AA_SFS_FILE_U64("capability",           VFS_CAP_FLAGS_MASK),
         AA_SFS_DIR("rlimit",                    aa_sfs_entry_rlimit),
diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c
index d0594446ae3f..ffc8c75a6785 100644
--- a/security/apparmor/domain.c
+++ b/security/apparmor/domain.c
@@ -374,8 +374,8 @@ static const char *next_name(int xtype, const char *name)
  *
  * Returns: refcounted label, or NULL on failure (MAYBE NULL)
  */
-static struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
-                                       const char **name)
+struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
+                                const char **name)
 {
         struct aa_label *label = NULL;
         u32 xtype = xindex & AA_X_TYPE_MASK;
diff --git a/security/apparmor/include/apparmor.h b/security/apparmor/include/apparmor.h
index 962a20a75e01..829082c35faa 100644
--- a/security/apparmor/include/apparmor.h
+++ b/security/apparmor/include/apparmor.h
@@ -27,6 +27,7 @@
 #define AA_CLASS_NET            4
 #define AA_CLASS_RLIMITS        5
 #define AA_CLASS_DOMAIN         6
+#define AA_CLASS_MOUNT          7
 #define AA_CLASS_PTRACE         9
 #define AA_CLASS_SIGNAL         10
 #define AA_CLASS_LABEL          16
diff --git a/security/apparmor/include/audit.h b/security/apparmor/include/audit.h
index d9a156ae11b9..c3fe1c5ef3bc 100644
--- a/security/apparmor/include/audit.h
+++ b/security/apparmor/include/audit.h
@@ -71,6 +71,10 @@ enum audit_type {
 #define OP_FMPROT "file_mprotect"
 #define OP_INHERIT "file_inherit"
 
+#define OP_PIVOTROOT "pivotroot"
+#define OP_MOUNT "mount"
+#define OP_UMOUNT "umount"
+
 #define OP_CREATE "create"
 #define OP_POST_CREATE "post_create"
 #define OP_BIND "bind"
@@ -132,6 +136,13 @@ struct apparmor_audit_data {
                         int rlim;
                         unsigned long max;
                 } rlim;
+                struct {
+                        const char *src_name;
+                        const char *type;
+                        const char *trans;
+                        const char *data;
+                        unsigned long flags;
+                } mnt;
         };
 };
 
diff --git a/security/apparmor/include/domain.h b/security/apparmor/include/domain.h
index bab5810b6e9a..db27403346c5 100644
--- a/security/apparmor/include/domain.h
+++ b/security/apparmor/include/domain.h
@@ -15,6 +15,8 @@
 #include <linux/binfmts.h>
 #include <linux/types.h>
 
+#include "label.h"
+
 #ifndef __AA_DOMAIN_H
 #define __AA_DOMAIN_H
 
@@ -29,6 +31,9 @@ struct aa_domain {
 #define AA_CHANGE_ONEXEC  4
 #define AA_CHANGE_STACK 8
 
+struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
+                                const char **name);
+
 int apparmor_bprm_set_creds(struct linux_binprm *bprm);
 int apparmor_bprm_secureexec(struct linux_binprm *bprm);
 
diff --git a/security/apparmor/include/mount.h b/security/apparmor/include/mount.h
new file mode 100644
index 000000000000..25d6067fa6ef
--- /dev/null
+++ b/security/apparmor/include/mount.h
@@ -0,0 +1,54 @@
+/*
+ * AppArmor security module
+ *
+ * This file contains AppArmor file mediation function definitions.
+ *
+ * Copyright 2017 Canonical Ltd.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2 of the
+ * License.
+ */
+
+#ifndef __AA_MOUNT_H
+#define __AA_MOUNT_H
+
+#include <linux/fs.h>
+#include <linux/path.h>
+
+#include "domain.h"
+#include "policy.h"
+
+/* mount perms */
+#define AA_MAY_PIVOTROOT        0x01
+#define AA_MAY_MOUNT            0x02
+#define AA_MAY_UMOUNT           0x04
+#define AA_AUDIT_DATA           0x40
+#define AA_MNT_CONT_MATCH       0x40
+
+#define AA_MS_IGNORE_MASK (MS_KERNMOUNT | MS_NOSEC | MS_ACTIVE | MS_BORN)
+
+int aa_remount(struct aa_label *label, const struct path *path,
+               unsigned long flags, void *data);
+
+int aa_bind_mount(struct aa_label *label, const struct path *path,
+                  const char *old_name, unsigned long flags);
+
+
+int aa_mount_change_type(struct aa_label *label, const struct path *path,
+                         unsigned long flags);
+
+int aa_move_mount(struct aa_label *label, const struct path *path,
+                  const char *old_name);
+
+int aa_new_mount(struct aa_label *label, const char *dev_name,
+                 const struct path *path, const char *type, unsigned long flags,
+                 void *data);
+
+int aa_umount(struct aa_label *label, struct vfsmount *mnt, int flags);
+
+int aa_pivotroot(struct aa_label *label, const struct path *old_path,