New helper: path_is_under(path1, path2)

Analog of is_subdir for vfsmount,dentry pairs, moved from audit_tree.c

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 37 insertions, 39 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index 4365998b8df4..74da947b160b 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2191,6 +2191,30 @@ int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry)
         return result;
 }
 
+int path_is_under(struct path *path1, struct path *path2)
+{
+        struct vfsmount *mnt = path1->mnt;
+        struct dentry *dentry = path1->dentry;
+        int res;
+        spin_lock(&vfsmount_lock);
+        if (mnt != path2->mnt) {
+                for (;;) {
+                        if (mnt->mnt_parent == mnt) {
+                                spin_unlock(&vfsmount_lock);
+                                return 0;
+                        }
+                        if (mnt->mnt_parent == path2->mnt)
+                                break;
+                        mnt = mnt->mnt_parent;
+                }
+                dentry = mnt->mnt_mountpoint;
+        }
+        res = is_subdir(dentry, path2->dentry);
+        spin_unlock(&vfsmount_lock);
+        return res;
+}
+EXPORT_SYMBOL(path_is_under);
+
 void d_genocide(struct dentry *root)
 {
         struct dentry *this_parent = root;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index d443c9dd3caa..8d53bc17f93f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2126,6 +2126,7 @@ extern struct file * open_exec(const char *);
  
 /* fs/dcache.c -- generic fs support functions */
 extern int is_subdir(struct dentry *, struct dentry *);
+extern int path_is_under(struct path *, struct path *);
 extern ino_t find_inode_number(struct dentry *, struct qstr *);
 
 #include <linux/err.h>
diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
index 4b05bd9479db..f09b42d9c32d 100644
--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -603,22 +603,6 @@ skip_it:
         mutex_unlock(&audit_filter_mutex);
 }
 
-static int is_under(struct vfsmount *mnt, struct dentry *dentry,
-                    struct path *path)
-{
-        if (mnt != path->mnt) {
-                for (;;) {
-                        if (mnt->mnt_parent == mnt)
-                                return 0;
-                        if (mnt->mnt_parent == path->mnt)
-                                        break;
-                        mnt = mnt->mnt_parent;
-                }
-                dentry = mnt->mnt_mountpoint;
-        }
-        return is_subdir(dentry, path->dentry);
-}
-
 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
 {
 
@@ -714,29 +698,24 @@ int audit_tag_tree(char *old, char *new)
 {
         struct list_head cursor, barrier;
         int failed = 0;
-        struct path path;
+        struct path path1, path2;
         struct vfsmount *tagged;
         struct list_head list;
-        struct vfsmount *mnt;
-        struct dentry *dentry;
         int err;
 
-        err = kern_path(new, 0, &path);
+        err = kern_path(new, 0, &path2);
         if (err)
                 return err;
-        tagged = collect_mounts(&path);
-        path_put(&path);
+        tagged = collect_mounts(&path2);
+        path_put(&path2);
         if (!tagged)
                 return -ENOMEM;
 
-        err = kern_path(old, 0, &path);
+        err = kern_path(old, 0, &path1);
         if (err) {
                 drop_collected_mounts(tagged);
                 return err;
         }
-        mnt = mntget(path.mnt);
-        dentry = dget(path.dentry);
-        path_put(&path);
 
         list_add_tail(&list, &tagged->mnt_list);
 
@@ -747,6 +726,7 @@ int audit_tag_tree(char *old, char *new)
         while (cursor.next != &tree_list) {
                 struct audit_tree *tree;
                 struct vfsmount *p;
+                int good_one = 0;
 
                 tree = container_of(cursor.next, struct audit_tree, list);
                 get_tree(tree);
@@ -754,23 +734,17 @@ int audit_tag_tree(char *old, char *new)
                 list_add(&cursor, &tree->list);
                 mutex_unlock(&audit_filter_mutex);
 
-                err = kern_path(tree->pathname, 0, &path);
-                if (err) {
-                        put_tree(tree);
-                        mutex_lock(&audit_filter_mutex);
-                        continue;
+                err = kern_path(tree->pathname, 0, &path2);
+                if (!err) {
+                        good_one = path_is_under(&path1, &path2);
+                        path_put(&path2);
                 }
 
-                spin_lock(&vfsmount_lock);
-                if (!is_under(mnt, dentry, &path)) {
-                        spin_unlock(&vfsmount_lock);
-                        path_put(&path);
+                if (!good_one) {
                         put_tree(tree);
                         mutex_lock(&audit_filter_mutex);
                         continue;
                 }
-                spin_unlock(&vfsmount_lock);
-                path_put(&path);
 
                 list_for_each_entry(p, &list, mnt_list) {
                         failed = tag_chunk(p->mnt_root->d_inode, tree);
@@ -820,8 +794,7 @@ int audit_tag_tree(char *old, char *new)
         list_del(&cursor);
         list_del(&list);
         mutex_unlock(&audit_filter_mutex);
-        dput(dentry);
-        mntput(mnt);
+        path_put(&path1);
         drop_collected_mounts(tagged);
         return failed;
 }