Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757013AbbDVDu6 (ORCPT ); Tue, 21 Apr 2015 23:50:58 -0400 Received: from mail-pa0-f50.google.com ([209.85.220.50]:35741 "EHLO mail-pa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756986AbbDVDuv (ORCPT ); Tue, 21 Apr 2015 23:50:51 -0400 From: Boqun Feng To: linux-fsdevel@vger.kernel.org, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org Cc: Boqun Feng , Al Viro , Oleg Drokin , Andreas Dilger , Greg Kroah-Hartman , Jan Kara Subject: [PATCH 1/2] vfs: export symbol 'getname' and 'putname' Date: Wed, 22 Apr 2015 11:50:23 +0800 Message-Id: <1429674624-25922-2-git-send-email-boqun.feng@gmail.com> X-Mailer: git-send-email 2.3.5 In-Reply-To: <1429674624-25922-1-git-send-email-boqun.feng@gmail.com> References: <1429674624-25922-1-git-send-email-boqun.feng@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2262 Lines: 73 getname/putname in fs/namei.c is a well-implemented way to copy a file name from userland, however other ways, such as directly calling __getname() and strncpy_from_user(), may lack features(e.g. auditing and reusing), introduce errors or at least reinvent wheels. Therefore for places need a kernel file name copy from userland, it's better to use getname and putname if possible. To be able to use these functions all over the kernel, symbols 'getname' and 'putname' are exported and comments of their behaviors and constraints are added. Suggested-by: Al Viro Signed-off-by: Boqun Feng --- fs/namei.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/fs/namei.c b/fs/namei.c index c83145a..472911c 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -199,11 +199,23 @@ error: return err; } +/** + * getname() - Get a file name copy from userland + * @filename: userland pointer to the file name + * + * If successful, return a 'struct filename' pointer and ->name is the pointer + * to the kernel copy of the file name, otherwise an ERR_PTR. + * + * getname() should only be called in a system call context, and for each + * getname() that returns a successful value, callers must ensure exactly one + * corresponding putname() is called before returning to userland. + */ struct filename * getname(const char __user * filename) { return getname_flags(filename, 0, NULL); } +EXPORT_SYMBOL(getname); struct filename * getname_kernel(const char * filename) @@ -242,6 +254,11 @@ getname_kernel(const char * filename) return result; } +/* putname() - Release a 'struct filename' structure + * @name: the 'struct filename' structure to be release + * + * See more at getname() + */ void putname(struct filename *name) { BUG_ON(name->refcnt <= 0); @@ -255,6 +272,7 @@ void putname(struct filename *name) } else __putname(name); } +EXPORT_SYMBOL(putname); static int check_acl(struct inode *inode, int mask) { -- 2.3.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/