From patchwork Fri Mar 11 16:02:18 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 12778311 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 10589C433FE for ; Fri, 11 Mar 2022 16:02:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349488AbiCKQDv (ORCPT ); Fri, 11 Mar 2022 11:03:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37638 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350428AbiCKQDk (ORCPT ); Fri, 11 Mar 2022 11:03:40 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id C64634E3BC for ; Fri, 11 Mar 2022 08:02:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1647014555; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=ilGm5MsrGcVXow52rFFtdj0YbYqX9AM62W1VECQWVlE=; b=VAdC7GVjfnBwIbBms+7Kxz0rZf2/TIO6up3dNz+g644JMrVzZ50oABBspPvtI/Ox/vDdWI 9HHLSX8q+cxAFos1dK561ntbcK0JfBld87AFbnQ7SshmBAZ96Telyj7x01t6sxqMFT7tVI qpXQj1ge8wzdwDi6meFURr8M25DOYps= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-99-Ng7loZ2EPzmp-sVX6vNM8w-1; Fri, 11 Mar 2022 11:02:31 -0500 X-MC-Unique: Ng7loZ2EPzmp-sVX6vNM8w-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 19D60FC80; Fri, 11 Mar 2022 16:02:30 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id EB50F866D6; Fri, 11 Mar 2022 16:02:18 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH] cachefiles: Fix volume coherency attribute From: David Howells To: torvalds@linux-foundation.org Cc: Rohith Surabattula , Jeff Layton , Steve French , linux-cifs@vger.kernel.org, linux-cachefs@redhat.com, dhowells@redhat.com, rohiths.msft@gmail.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Fri, 11 Mar 2022 16:02:18 +0000 Message-ID: <164701453798.2588911.12798385110642752783.stgit@warthog.procyon.org.uk> User-Agent: StGit/1.4 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org A network filesystem may set coherency data on a volume cookie, and if given, cachefiles will store this in an xattr on the directory in the cache corresponding to the volume. The function that sets the xattr just stores the contents of the volume coherency buffer directly into the xattr, with nothing added; the checking function, on the other hand, has a cut'n'paste error whereby it tries to interpret the xattr contents as would be the xattr on an ordinary file (using the cachefiles_xattr struct). This results in a failure to match the coherency data because the buffer ends up being shifted by 18 bytes. Fix this by defining a structure specifically for the volume xattr and making both the setting and checking functions use it. Since the volume coherency doesn't work if used, take the opportunity to insert a reserved field for future use, set it to 0 and check that it is 0. Log mismatch through the appropriate tracepoint. Note that this only affects cifs; 9p, afs, ceph and nfs don't use the volume coherency data at the moment. Fixes: 32e150037dce ("fscache, cachefiles: Store the volume coherency data") Reported-by: Rohith Surabattula Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: Steve French cc: linux-cifs@vger.kernel.org cc: linux-cachefs@redhat.com --- fs/cachefiles/xattr.c | 23 ++++++++++++++++++++--- include/trace/events/cachefiles.h | 2 ++ 2 files changed, 22 insertions(+), 3 deletions(-) diff --git a/fs/cachefiles/xattr.c b/fs/cachefiles/xattr.c index 83f41bd0c3a9..35465109d9c4 100644 --- a/fs/cachefiles/xattr.c +++ b/fs/cachefiles/xattr.c @@ -28,6 +28,11 @@ struct cachefiles_xattr { static const char cachefiles_xattr_cache[] = XATTR_USER_PREFIX "CacheFiles.cache"; +struct cachefiles_vol_xattr { + __be32 reserved; /* Reserved, should be 0 */ + __u8 data[]; /* netfs volume coherency data */ +} __packed; + /* * set the state xattr on a cache file */ @@ -185,6 +190,7 @@ void cachefiles_prepare_to_write(struct fscache_cookie *cookie) */ bool cachefiles_set_volume_xattr(struct cachefiles_volume *volume) { + struct cachefiles_vol_xattr *buf; unsigned int len = volume->vcookie->coherency_len; const void *p = volume->vcookie->coherency; struct dentry *dentry = volume->dentry; @@ -192,10 +198,17 @@ bool cachefiles_set_volume_xattr(struct cachefiles_volume *volume) _enter("%x,#%d", volume->vcookie->debug_id, len); + len += sizeof(*buf); + buf = kmalloc(len, GFP_KERNEL); + if (!buf) + return false; + buf->reserved = cpu_to_be32(0); + memcpy(buf->data, p, len); + ret = cachefiles_inject_write_error(); if (ret == 0) ret = vfs_setxattr(&init_user_ns, dentry, cachefiles_xattr_cache, - p, len, 0); + buf, len, 0); if (ret < 0) { trace_cachefiles_vfs_error(NULL, d_inode(dentry), ret, cachefiles_trace_setxattr_error); @@ -209,6 +222,7 @@ bool cachefiles_set_volume_xattr(struct cachefiles_volume *volume) cachefiles_coherency_vol_set_ok); } + kfree(buf); _leave(" = %d", ret); return ret == 0; } @@ -218,7 +232,7 @@ bool cachefiles_set_volume_xattr(struct cachefiles_volume *volume) */ int cachefiles_check_volume_xattr(struct cachefiles_volume *volume) { - struct cachefiles_xattr *buf; + struct cachefiles_vol_xattr *buf; struct dentry *dentry = volume->dentry; unsigned int len = volume->vcookie->coherency_len; const void *p = volume->vcookie->coherency; @@ -228,6 +242,7 @@ int cachefiles_check_volume_xattr(struct cachefiles_volume *volume) _enter(""); + len += sizeof(*buf); buf = kmalloc(len, GFP_KERNEL); if (!buf) return -ENOMEM; @@ -245,7 +260,9 @@ int cachefiles_check_volume_xattr(struct cachefiles_volume *volume) "Failed to read xattr with error %zd", xlen); } why = cachefiles_coherency_vol_check_xattr; - } else if (memcmp(buf->data, p, len) != 0) { + } else if (buf->reserved != cpu_to_be32(0)) { + why = cachefiles_coherency_vol_check_resv; + } else if (memcmp(buf->data, p, len - sizeof(*buf)) != 0) { why = cachefiles_coherency_vol_check_cmp; } else { why = cachefiles_coherency_vol_check_ok; diff --git a/include/trace/events/cachefiles.h b/include/trace/events/cachefiles.h index 002d0ae4f9bc..311c14a20e70 100644 --- a/include/trace/events/cachefiles.h +++ b/include/trace/events/cachefiles.h @@ -56,6 +56,7 @@ enum cachefiles_coherency_trace { cachefiles_coherency_set_ok, cachefiles_coherency_vol_check_cmp, cachefiles_coherency_vol_check_ok, + cachefiles_coherency_vol_check_resv, cachefiles_coherency_vol_check_xattr, cachefiles_coherency_vol_set_fail, cachefiles_coherency_vol_set_ok, @@ -139,6 +140,7 @@ enum cachefiles_error_trace { EM(cachefiles_coherency_set_ok, "SET ok ") \ EM(cachefiles_coherency_vol_check_cmp, "VOL BAD cmp ") \ EM(cachefiles_coherency_vol_check_ok, "VOL OK ") \ + EM(cachefiles_coherency_vol_check_resv, "VOL BAD resv") \ EM(cachefiles_coherency_vol_check_xattr,"VOL BAD xatt") \ EM(cachefiles_coherency_vol_set_fail, "VOL SET fail") \ E_(cachefiles_coherency_vol_set_ok, "VOL SET ok ")