new helper: user_path_locked_at()

Equivalent of kern_path_locked() taking dfd/userland name.
User introduced in the next commit.

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

diff --git a/fs/namei.c b/fs/namei.c
index 71c13b2990b44f426a778bb0ad8f969a89387b4f..3ffbe268d52c2451ea7b58b6746a7b73c6287406 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2573,13 +2573,13 @@ static int filename_parentat(int dfd, struct filename *name,
 }
 
 /* does lookup, returns the object with parent locked */
-static struct dentry *__kern_path_locked(struct filename *name, struct path *path)
+static struct dentry *__kern_path_locked(int dfd, struct filename *name, struct path *path)
 {
        struct dentry *d;
        struct qstr last;
        int type, error;
 
-       error = filename_parentat(AT_FDCWD, name, 0, path, &last, &type);
+       error = filename_parentat(dfd, name, 0, path, &last, &type);
        if (error)
                return ERR_PTR(error);
        if (unlikely(type != LAST_NORM)) {
@@ -2598,12 +2598,22 @@ static struct dentry *__kern_path_locked(struct filename *name, struct path *pat
 struct dentry *kern_path_locked(const char *name, struct path *path)
 {
        struct filename *filename = getname_kernel(name);
-       struct dentry *res = __kern_path_locked(filename, path);
+       struct dentry *res = __kern_path_locked(AT_FDCWD, filename, path);
 
        putname(filename);
        return res;
 }
 
+struct dentry *user_path_locked_at(int dfd, const char __user *name, struct path *path)
+{
+       struct filename *filename = getname(name);
+       struct dentry *res = __kern_path_locked(dfd, filename, path);
+
+       putname(filename);
+       return res;
+}
+EXPORT_SYMBOL(user_path_locked_at);
+
 int kern_path(const char *name, unsigned int flags, struct path *path)
 {
        struct filename *filename = getname_kernel(name);

diff --git a/include/linux/namei.h b/include/linux/namei.h
index 3100371b5e3218a92039b363e3508b5c69166238..74e0cc14ebf86bb9444b54d628908f976125ff3f 100644 (file)
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -66,6 +66,7 @@ extern struct dentry *kern_path_create(int, const char *, struct path *, unsigne
 extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
 extern void done_path_create(struct path *, struct dentry *);
 extern struct dentry *kern_path_locked(const char *, struct path *);
+extern struct dentry *user_path_locked_at(int , const char __user *, struct path *);
 int vfs_path_parent_lookup(struct filename *filename, unsigned int flags,
                           struct path *parent, struct qstr *last, int *type,
                           const struct path *root);