4 files changed, 28 insertions, 0 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index 3ddfd9046c44..1b3f2ac59c5e 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1800,6 +1800,10 @@ static int do_remount(struct path *path, int flags, int mnt_flags,
         if (path->dentry != path->mnt->mnt_root)
                 return -EINVAL;
 
+        err = security_sb_remount(sb, data);
+        if (err)
+                return err;
+
         down_write(&sb->s_umount);
         if (flags & MS_BIND)
                 err = change_mount_flags(path->mnt, flags);
diff --git a/include/linux/security.h b/include/linux/security.h
index 14167f2eb35a..d11ac43ecc49 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -268,6 +268,12 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
  *      @orig the original mount data copied from userspace.
  *      @copy copied data which will be passed to the security module.
  *      Returns 0 if the copy was successful.
+ * @sb_remount:
+ *      Extracts security system specifc mount options and verifys no changes
+ *      are being made to those options.
+ *      @sb superblock being remounted
+ *      @data contains the filesystem-specific data.
+ *      Return 0 if permission is granted.
  * @sb_umount:
  *      Check permission before the @mnt file system is unmounted.
  *      @mnt contains the mounted file system.
@@ -1394,6 +1400,7 @@ struct security_operations {
         int (*sb_alloc_security) (struct super_block *sb);
         void (*sb_free_security) (struct super_block *sb);
         int (*sb_copy_data) (char *orig, char *copy);
+        int (*sb_remount) (struct super_block *sb, void *data);
         int (*sb_kern_mount) (struct super_block *sb, int flags, void *data);
         int (*sb_show_options) (struct seq_file *m, struct super_block *sb);
         int (*sb_statfs) (struct dentry *dentry);
@@ -1676,6 +1683,7 @@ int security_bprm_secureexec(struct linux_binprm *bprm);
 int security_sb_alloc(struct super_block *sb);
 void security_sb_free(struct super_block *sb);
 int security_sb_copy_data(char *orig, char *copy);
+int security_sb_remount(struct super_block *sb, void *data);
 int security_sb_kern_mount(struct super_block *sb, int flags, void *data);
 int security_sb_show_options(struct seq_file *m, struct super_block *sb);
 int security_sb_statfs(struct dentry *dentry);
@@ -1955,6 +1963,11 @@ static inline int security_sb_copy_data(char *orig, char *copy)
         return 0;
 }
 
+static inline int security_sb_remount(struct super_block *sb, void *data)
+{
+        return 0;
+}
+
 static inline int security_sb_kern_mount(struct super_block *sb, int flags, void *data)
 {
         return 0;
diff --git a/security/capability.c b/security/capability.c
index 85b67c8632df..ab3d807accc3 100644
--- a/security/capability.c
+++ b/security/capability.c
@@ -54,6 +54,11 @@ static int cap_sb_copy_data(char *orig, char *copy)
         return 0;
 }
 
+static int cap_sb_remount(struct super_block *sb, void *data)
+{
+        return 0;
+}
+
 static int cap_sb_kern_mount(struct super_block *sb, int flags, void *data)
 {
         return 0;
@@ -887,6 +892,7 @@ void __init security_fixup_ops(struct security_operations *ops)
         set_to_cap_if_null(ops, sb_alloc_security);
         set_to_cap_if_null(ops, sb_free_security);
         set_to_cap_if_null(ops, sb_copy_data);
+        set_to_cap_if_null(ops, sb_remount);
         set_to_cap_if_null(ops, sb_kern_mount);
         set_to_cap_if_null(ops, sb_show_options);
         set_to_cap_if_null(ops, sb_statfs);
diff --git a/security/security.c b/security/security.c
index 8f28685ee0d9..b1d6134548bc 100644
--- a/security/security.c
+++ b/security/security.c
@@ -267,6 +267,11 @@ int security_sb_copy_data(char *orig, char *copy)
 }
 EXPORT_SYMBOL(security_sb_copy_data);
 
+int security_sb_remount(struct super_block *sb, void *data)
+{
+        return security_ops->sb_remount(sb, data);
+}
+
 int security_sb_kern_mount(struct super_block *sb, int flags, void *data)
 {
         return security_ops->sb_kern_mount(sb, flags, data);