X-Git-Url: https://git.karo-electronics.de/?a=blobdiff_plain;f=fs%2Fnamespace.c;h=fbba8b17330d40d4daff7cf61763853cfd414395;hb=d5dbc0245a7da65b95fc14f99ccfc5f1fad078f0;hp=99572dd083361649d937cd49971303357e9fc78e;hpb=0a5eb7c8189922e86a840972cd0b57e41de6f031;p=karo-tx-linux.git

diff --git a/fs/namespace.c b/fs/namespace.c
index 99572dd08336..fbba8b17330d 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -703,11 +703,10 @@ out:
 	return is_covered;
 }
 
-static struct mountpoint *new_mountpoint(struct dentry *dentry)
+static struct mountpoint *lookup_mountpoint(struct dentry *dentry)
 {
 	struct hlist_head *chain = mp_hash(dentry);
 	struct mountpoint *mp;
-	int ret;
 
 	hlist_for_each_entry(mp, chain, m_hash) {
 		if (mp->m_dentry == dentry) {
@@ -718,6 +717,14 @@ static struct mountpoint *new_mountpoint(struct dentry *dentry)
 			return mp;
 		}
 	}
+	return NULL;
+}
+
+static struct mountpoint *new_mountpoint(struct dentry *dentry)
+{
+	struct hlist_head *chain = mp_hash(dentry);
+	struct mountpoint *mp;
+	int ret;
 
 	mp = kmalloc(sizeof(struct mountpoint), GFP_KERNEL);
 	if (!mp)
@@ -1432,6 +1439,8 @@ static int do_umount(struct mount *mnt, int flags)
 		 * Special case for "unmounting" root ...
 		 * we just try to remount it readonly.
 		 */
+		if (!capable(CAP_SYS_ADMIN))
+			return -EPERM;
 		down_write(&sb->s_umount);
 		if (!(sb->s_flags & MS_RDONLY))
 			retval = do_remount_sb(sb, MS_RDONLY, NULL, 0);
@@ -1461,6 +1470,37 @@ static int do_umount(struct mount *mnt, int flags)
 	return retval;
 }
 
+/*
+ * __detach_mounts - lazily unmount all mounts on the specified dentry
+ *
+ * During unlink, rmdir, and d_drop it is possible to loose the path
+ * to an existing mountpoint, and wind up leaking the mount.
+ * detach_mounts allows lazily unmounting those mounts instead of
+ * leaking them.
+ *
+ * The caller may hold dentry->d_inode->i_mutex.
+ */
+void __detach_mounts(struct dentry *dentry)
+{
+	struct mountpoint *mp;
+	struct mount *mnt;
+
+	namespace_lock();
+	mp = lookup_mountpoint(dentry);
+	if (!mp)
+		goto out_unlock;
+
+	lock_mount_hash();
+	while (!hlist_empty(&mp->m_list)) {
+		mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list);
+		umount_tree(mnt, 2);
+	}
+	unlock_mount_hash();
+	put_mountpoint(mp);
+out_unlock:
+	namespace_unlock();
+}
+
 /* 
  * Is the caller allowed to modify his namespace?
  */
@@ -1818,7 +1858,9 @@ retry:
 	namespace_lock();
 	mnt = lookup_mnt(path);
 	if (likely(!mnt)) {
-		struct mountpoint *mp = new_mountpoint(dentry);
+		struct mountpoint *mp = lookup_mountpoint(dentry);
+		if (!mp)
+			mp = new_mountpoint(dentry);
 		if (IS_ERR(mp)) {
 			namespace_unlock();
 			mutex_unlock(&dentry->d_inode->i_mutex);
@@ -2474,21 +2516,9 @@ int copy_mount_options(const void __user * data, unsigned long *where)
 	return 0;
 }
 
-int copy_mount_string(const void __user *data, char **where)
+char *copy_mount_string(const void __user *data)
 {
-	char *tmp;
-
-	if (!data) {
-		*where = NULL;
-		return 0;
-	}
-
-	tmp = strndup_user(data, PAGE_SIZE);
-	if (IS_ERR(tmp))
-		return PTR_ERR(tmp);
-
-	*where = tmp;
-	return 0;
+	return data ? strndup_user(data, PAGE_SIZE) : NULL;
 }
 
 /*
@@ -2505,7 +2535,7 @@ int copy_mount_string(const void __user *data, char **where)
  * Therefore, if this magic number is present, it carries no information
  * and must be discarded.
  */
-long do_mount(const char *dev_name, const char *dir_name,
+long do_mount(const char *dev_name, const char __user *dir_name,
 		const char *type_page, unsigned long flags, void *data_page)
 {
 	struct path path;
@@ -2517,15 +2547,11 @@ long do_mount(const char *dev_name, const char *dir_name,
 		flags &= ~MS_MGC_MSK;
 
 	/* Basic sanity checks */
-
-	if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE))
-		return -EINVAL;
-
 	if (data_page)
 		((char *)data_page)[PAGE_SIZE - 1] = 0;
 
 	/* ... and get the mountpoint */
-	retval = kern_path(dir_name, LOOKUP_FOLLOW, &path);
+	retval = user_path(dir_name, &path);
 	if (retval)
 		return retval;
 
@@ -2750,37 +2776,30 @@ SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
 {
 	int ret;
 	char *kernel_type;
-	struct filename *kernel_dir;
 	char *kernel_dev;
 	unsigned long data_page;
 
-	ret = copy_mount_string(type, &kernel_type);
-	if (ret < 0)
+	kernel_type = copy_mount_string(type);
+	ret = PTR_ERR(kernel_type);
+	if (IS_ERR(kernel_type))
 		goto out_type;
 
-	kernel_dir = getname(dir_name);
-	if (IS_ERR(kernel_dir)) {
-		ret = PTR_ERR(kernel_dir);
-		goto out_dir;
-	}
-
-	ret = copy_mount_string(dev_name, &kernel_dev);
-	if (ret < 0)
+	kernel_dev = copy_mount_string(dev_name);
+	ret = PTR_ERR(kernel_dev);
+	if (IS_ERR(kernel_dev))
 		goto out_dev;
 
 	ret = copy_mount_options(data, &data_page);
 	if (ret < 0)
 		goto out_data;
 
-	ret = do_mount(kernel_dev, kernel_dir->name, kernel_type, flags,
+	ret = do_mount(kernel_dev, dir_name, kernel_type, flags,
 		(void *) data_page);
 
 	free_page(data_page);
 out_data:
 	kfree(kernel_dev);
 out_dev:
-	putname(kernel_dir);
-out_dir:
 	kfree(kernel_type);
 out_type:
 	return ret;
@@ -2896,6 +2915,9 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
 	/* make sure we can reach put_old from new_root */
 	if (!is_path_reachable(old_mnt, old.dentry, &new))
 		goto out4;
+	/* make certain new is below the root */
+	if (!is_path_reachable(new_mnt, new.dentry, &root))
+		goto out4;
 	root_mp->m_count++; /* pin it so it won't go away */
 	lock_mount_hash();
 	detach_mnt(new_mnt, &parent_path);