Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754206AbbEKSMS (ORCPT ); Mon, 11 May 2015 14:12:18 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:47597 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755063AbbEKSIa (ORCPT ); Mon, 11 May 2015 14:08:30 -0400 From: Al Viro To: Linus Torvalds Cc: Neil Brown , Christoph Hellwig , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCH v3 102/110] namei: make may_follow_link() safe in RCU mode Date: Mon, 11 May 2015 19:08:02 +0100 Message-Id: <1431367690-5223-102-git-send-email-viro@ZenIV.linux.org.uk> X-Mailer: git-send-email 1.7.7.6 In-Reply-To: <20150511180650.GA4147@ZenIV.linux.org.uk> References: <20150511180650.GA4147@ZenIV.linux.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1220 Lines: 39 From: Al Viro We *can't* call that audit garbage in RCU mode - it's doing a weird mix of allocations (GFP_NOFS, immediately followed by GFP_KERNEL) and I'm not touching that... thing again. So if this security sclero^Whardening feature gets triggered when we are in RCU mode, tough - we'll fail with -ECHILD and have everything restarted in non-RCU mode. Only to hit the same test and fail, this time with EACCES and with (oh, rapture) an audit spew produced. Signed-off-by: Al Viro --- fs/namei.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/namei.c b/fs/namei.c index 998c3c2..20bf494 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -794,6 +794,9 @@ static inline int may_follow_link(struct nameidata *nd) if (uid_eq(parent->i_uid, inode->i_uid)) return 0; + if (nd->flags & LOOKUP_RCU) + return -ECHILD; + audit_log_link_denied("follow_link", &nd->stack[0].link); return -EACCES; } -- 2.1.4 -- 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/