Merge branch 'misc.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull namei updates from Al Viro:
 "Clearing fallout from mkdirat in io_uring series. The fix in the
  kern_path_locked() patch plus associated cleanups"

* 'misc.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  putname(): IS_ERR_OR_NULL() is wrong here
  namei: Standardize callers of filename_create()
  namei: Standardize callers of filename_lookup()
  rename __filename_parentat() to filename_parentat()
  namei: Fix use after free in kern_path_locked

2 files changed, 58 insertions, 59 deletions

diff --git a/fs/fs_parser.c b/fs/fs_parser.c
index 980d44fd3a36..3df07c0e32b3 100644
--- a/fs/fs_parser.c
+++ b/fs/fs_parser.c
@@ -165,7 +165,6 @@ int fs_lookup_param(struct fs_context *fc,
 		return invalf(fc, "%s: not usable as path", param->key);
 	}
 
-	f->refcnt++; /* filename_lookup() drops our ref. */
 	ret = filename_lookup(param->dirfd, f, flags, _path, NULL);
 	if (ret < 0) {
 		errorf(fc, "%s: Lookup failure for '%s'", param->key, f->name);
diff --git a/fs/namei.c b/fs/namei.c
index 95a881e0552b..1946d9667790 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -255,7 +255,7 @@ getname_kernel(const char * filename)
 
 void putname(struct filename *name)
 {
-	if (IS_ERR_OR_NULL(name))
+	if (IS_ERR(name))
 		return;
 
 	BUG_ON(name->refcnt <= 0);
@@ -2467,7 +2467,7 @@ static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path
 	return err;
 }
 
-static int __filename_lookup(int dfd, struct filename *name, unsigned flags,
+int filename_lookup(int dfd, struct filename *name, unsigned flags,
 		    struct path *path, struct path *root)
 {
 	int retval;
@@ -2488,15 +2488,6 @@ static int __filename_lookup(int dfd, struct filename *name, unsigned flags,
 	return retval;
 }
 
-int filename_lookup(int dfd, struct filename *name, unsigned flags,
-		    struct path *path, struct path *root)
-{
-	int retval = __filename_lookup(dfd, name, flags, path, root);
-
-	putname(name);
-	return retval;
-}
-
 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
 static int path_parentat(struct nameidata *nd, unsigned flags,
 				struct path *parent)
@@ -2514,9 +2505,10 @@ static int path_parentat(struct nameidata *nd, unsigned flags,
 	return err;
 }
 
-static int __filename_parentat(int dfd, struct filename *name,
-				unsigned int flags, struct path *parent,
-				struct qstr *last, int *type)
+/* Note: this does not consume "name" */
+static int filename_parentat(int dfd, struct filename *name,
+			     unsigned int flags, struct path *parent,
+			     struct qstr *last, int *type)
 {
 	int retval;
 	struct nameidata nd;
@@ -2538,25 +2530,14 @@ static int __filename_parentat(int dfd, struct filename *name,
 	return retval;
 }
 
-static int filename_parentat(int dfd, struct filename *name,
-				unsigned int flags, struct path *parent,
-				struct qstr *last, int *type)
-{
-	int retval = __filename_parentat(dfd, name, flags, parent, last, type);
-
-	putname(name);
-	return retval;
-}
-
 /* does lookup, returns the object with parent locked */
-struct dentry *kern_path_locked(const char *name, struct path *path)
+static struct dentry *__kern_path_locked(struct filename *name, struct path *path)
 {
 	struct dentry *d;
 	struct qstr last;
 	int type, error;
 
-	error = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path,
-				    &last, &type);
+	error = filename_parentat(AT_FDCWD, name, 0, path, &last, &type);
 	if (error)
 		return ERR_PTR(error);
 	if (unlikely(type != LAST_NORM)) {
@@ -2572,10 +2553,23 @@ struct dentry *kern_path_locked(const char *name, struct path *path)
 	return d;
 }
 
+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);
+
+	putname(filename);
+	return res;
+}
+
 int kern_path(const char *name, unsigned int flags, struct path *path)
 {
-	return filename_lookup(AT_FDCWD, getname_kernel(name),
-			       flags, path, NULL);
+	struct filename *filename = getname_kernel(name);
+	int ret = filename_lookup(AT_FDCWD, filename, flags, path, NULL);
+
+	putname(filename);
+	return ret;
+
 }
 EXPORT_SYMBOL(kern_path);
 
@@ -2591,10 +2585,15 @@ int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
 		    const char *name, unsigned int flags,
 		    struct path *path)
 {
+	struct filename *filename;
 	struct path root = {.mnt = mnt, .dentry = dentry};
+	int ret;
+
+	filename = getname_kernel(name);
 	/* the first argument of filename_lookup() is ignored with root */
-	return filename_lookup(AT_FDCWD, getname_kernel(name),
-			       flags , path, &root);
+	ret = filename_lookup(AT_FDCWD, filename, flags, path, &root);
+	putname(filename);
+	return ret;
 }
 EXPORT_SYMBOL(vfs_path_lookup);
 
@@ -2798,8 +2797,11 @@ int path_pts(struct path *path)
 int user_path_at_empty(int dfd, const char __user *name, unsigned flags,
 		 struct path *path, int *empty)
 {
-	return filename_lookup(dfd, getname_flags(name, flags, empty),
-			       flags, path, NULL);
+	struct filename *filename = getname_flags(name, flags, empty);
+	int ret = filename_lookup(dfd, filename, flags, path, NULL);
+
+	putname(filename);
+	return ret;
 }
 EXPORT_SYMBOL(user_path_at_empty);
 
@@ -3618,8 +3620,8 @@ struct file *do_file_open_root(const struct path *root,
 	return file;
 }
 
-static struct dentry *__filename_create(int dfd, struct filename *name,
-				struct path *path, unsigned int lookup_flags)
+static struct dentry *filename_create(int dfd, struct filename *name,
+				      struct path *path, unsigned int lookup_flags)
 {
 	struct dentry *dentry = ERR_PTR(-EEXIST);
 	struct qstr last;
@@ -3634,7 +3636,7 @@ static struct dentry *__filename_create(int dfd, struct filename *name,
 	 */
 	lookup_flags &= LOOKUP_REVAL;
 
-	error = __filename_parentat(dfd, name, lookup_flags, path, &last, &type);
+	error = filename_parentat(dfd, name, lookup_flags, path, &last, &type);
 	if (error)
 		return ERR_PTR(error);
 
@@ -3687,21 +3689,15 @@ out:
 	return dentry;
 }
 
-static inline struct dentry *filename_create(int dfd, struct filename *name,
+struct dentry *kern_path_create(int dfd, const char *pathname,
 				struct path *path, unsigned int lookup_flags)
 {
-	struct dentry *res = __filename_create(dfd, name, path, lookup_flags);
+	struct filename *filename = getname_kernel(pathname);
+	struct dentry *res = filename_create(dfd, filename, path, lookup_flags);
 
-	putname(name);
+	putname(filename);
 	return res;
 }
-
-struct dentry *kern_path_create(int dfd, const char *pathname,
-				struct path *path, unsigned int lookup_flags)
-{
-	return filename_create(dfd, getname_kernel(pathname),
-				path, lookup_flags);
-}
 EXPORT_SYMBOL(kern_path_create);
 
 void done_path_create(struct path *path, struct dentry *dentry)
@@ -3716,7 +3712,11 @@ EXPORT_SYMBOL(done_path_create);
 inline struct dentry *user_path_create(int dfd, const char __user *pathname,
 				struct path *path, unsigned int lookup_flags)
 {
-	return filename_create(dfd, getname(pathname), path, lookup_flags);
+	struct filename *filename = getname(pathname);
+	struct dentry *res = filename_create(dfd, filename, path, lookup_flags);
+
+	putname(filename);
+	return res;
 }
 EXPORT_SYMBOL(user_path_create);
 
@@ -3797,7 +3797,7 @@ static int do_mknodat(int dfd, struct filename *name, umode_t mode,
 	if (error)
 		goto out1;
 retry:
-	dentry = __filename_create(dfd, name, &path, lookup_flags);
+	dentry = filename_create(dfd, name, &path, lookup_flags);
 	error = PTR_ERR(dentry);
 	if (IS_ERR(dentry))
 		goto out1;
@@ -3897,7 +3897,7 @@ int do_mkdirat(int dfd, struct filename *name, umode_t mode)
 	unsigned int lookup_flags = LOOKUP_DIRECTORY;
 
 retry:
-	dentry = __filename_create(dfd, name, &path, lookup_flags);
+	dentry = filename_create(dfd, name, &path, lookup_flags);
 	error = PTR_ERR(dentry);
 	if (IS_ERR(dentry))
 		goto out_putname;
@@ -3996,7 +3996,7 @@ int do_rmdir(int dfd, struct filename *name)
 	int type;
 	unsigned int lookup_flags = 0;
 retry:
-	error = __filename_parentat(dfd, name, lookup_flags, &path, &last, &type);
+	error = filename_parentat(dfd, name, lookup_flags, &path, &last, &type);
 	if (error)
 		goto exit1;
 
@@ -4137,7 +4137,7 @@ int do_unlinkat(int dfd, struct filename *name)
 	struct inode *delegated_inode = NULL;
 	unsigned int lookup_flags = 0;
 retry:
-	error = __filename_parentat(dfd, name, lookup_flags, &path, &last, &type);
+	error = filename_parentat(dfd, name, lookup_flags, &path, &last, &type);
 	if (error)
 		goto exit1;
 
@@ -4266,7 +4266,7 @@ int do_symlinkat(struct filename *from, int newdfd, struct filename *to)
 		goto out_putnames;
 	}
 retry:
-	dentry = __filename_create(newdfd, to, &path, lookup_flags);
+	dentry = filename_create(newdfd, to, &path, lookup_flags);
 	error = PTR_ERR(dentry);
 	if (IS_ERR(dentry))
 		goto out_putnames;
@@ -4426,11 +4426,11 @@ int do_linkat(int olddfd, struct filename *old, int newdfd,
 	if (flags & AT_SYMLINK_FOLLOW)
 		how |= LOOKUP_FOLLOW;
 retry:
-	error = __filename_lookup(olddfd, old, how, &old_path, NULL);
+	error = filename_lookup(olddfd, old, how, &old_path, NULL);
 	if (error)
 		goto out_putnames;
 
-	new_dentry = __filename_create(newdfd, new, &new_path,
+	new_dentry = filename_create(newdfd, new, &new_path,
 					(how & LOOKUP_REVAL));
 	error = PTR_ERR(new_dentry);
 	if (IS_ERR(new_dentry))
@@ -4689,13 +4689,13 @@ int do_renameat2(int olddfd, struct filename *from, int newdfd,
 		target_flags = 0;
 
 retry:
-	error = __filename_parentat(olddfd, from, lookup_flags, &old_path,
-					&old_last, &old_type);
+	error = filename_parentat(olddfd, from, lookup_flags, &old_path,
+				  &old_last, &old_type);
 	if (error)
 		goto put_names;
 
-	error = __filename_parentat(newdfd, to, lookup_flags, &new_path, &new_last,
-				&new_type);
+	error = filename_parentat(newdfd, to, lookup_flags, &new_path, &new_last,
+				  &new_type);
 	if (error)
 		goto exit1;