* [PATCH] ceph: check i_nlink while converting a file handle to dentry
@ 2017-05-17 11:21 Luis Henriques
2017-05-18 13:36 ` Yan, Zheng
0 siblings, 1 reply; 4+ messages in thread
From: Luis Henriques @ 2017-05-17 11:21 UTC (permalink / raw)
To: Yan, Zheng, Sage Weil, Ilya Dryomov
Cc: ceph-devel, linux-kernel, Luis Henriques
Converting a file handle to a dentry can be done call after the inode
unlink. This means that __fh_to_dentry() requires an extra check to
verify the number of links is not 0.
The issue can be easily reproduced using xfstest generic/426, which does
something like:
name_to_handle_at(&fh)
echo 3 > /proc/sys/vm/drop_caches
unlink()
open_by_handle_at(&fh)
The call to open_by_handle_at() should fail, as the file doesn't exist
anymore.
Cc: stable@vger.kernel.org
Link: http://tracker.ceph.com/issues/19958
Signed-off-by: Luis Henriques <lhenriques@suse.com>
---
fs/ceph/export.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/fs/ceph/export.c b/fs/ceph/export.c
index e8f11fa565c5..7df550c13d7f 100644
--- a/fs/ceph/export.c
+++ b/fs/ceph/export.c
@@ -91,6 +91,10 @@ static struct dentry *__fh_to_dentry(struct super_block *sb, u64 ino)
ceph_mdsc_put_request(req);
if (!inode)
return ERR_PTR(-ESTALE);
+ if (inode->i_nlink == 0) {
+ iput(inode);
+ return ERR_PTR(-ESTALE);
+ }
}
return d_obtain_alias(inode);
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] ceph: check i_nlink while converting a file handle to dentry
2017-05-17 11:21 [PATCH] ceph: check i_nlink while converting a file handle to dentry Luis Henriques
@ 2017-05-18 13:36 ` Yan, Zheng
2017-05-18 16:48 ` Luis Henriques
0 siblings, 1 reply; 4+ messages in thread
From: Yan, Zheng @ 2017-05-18 13:36 UTC (permalink / raw)
To: Luis Henriques
Cc: Sage Weil, Ilya Dryomov, ceph-devel, Linux Kernel Mailing List
> On 17 May 2017, at 19:21, Luis Henriques <lhenriques@suse.com> wrote:
>
> Converting a file handle to a dentry can be done call after the inode
> unlink. This means that __fh_to_dentry() requires an extra check to
> verify the number of links is not 0.
>
> The issue can be easily reproduced using xfstest generic/426, which does
> something like:
>
> name_to_handle_at(&fh)
> echo 3 > /proc/sys/vm/drop_caches
> unlink()
> open_by_handle_at(&fh)
>
> The call to open_by_handle_at() should fail, as the file doesn't exist
> anymore.
>
> Cc: stable@vger.kernel.org
> Link: http://tracker.ceph.com/issues/19958
> Signed-off-by: Luis Henriques <lhenriques@suse.com>
> ---
> fs/ceph/export.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/fs/ceph/export.c b/fs/ceph/export.c
> index e8f11fa565c5..7df550c13d7f 100644
> --- a/fs/ceph/export.c
> +++ b/fs/ceph/export.c
> @@ -91,6 +91,10 @@ static struct dentry *__fh_to_dentry(struct super_block *sb, u64 ino)
> ceph_mdsc_put_request(req);
> if (!inode)
> return ERR_PTR(-ESTALE);
> + if (inode->i_nlink == 0) {
> + iput(inode);
> + return ERR_PTR(-ESTALE);
> + }
> }
maybe we should do this check in MDS
Regards
Yan, Zheng
>
> return d_obtain_alias(inode);
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] ceph: check i_nlink while converting a file handle to dentry
2017-05-18 13:36 ` Yan, Zheng
@ 2017-05-18 16:48 ` Luis Henriques
2017-05-19 0:41 ` Yan, Zheng
0 siblings, 1 reply; 4+ messages in thread
From: Luis Henriques @ 2017-05-18 16:48 UTC (permalink / raw)
To: Yan, Zheng; +Cc: Sage Weil, Ilya Dryomov, ceph-devel, Linux Kernel Mailing List
On Thu, May 18, 2017 at 09:36:44PM +0800, Yan, Zheng wrote:
>
> > On 17 May 2017, at 19:21, Luis Henriques <lhenriques@suse.com> wrote:
> >
> > Converting a file handle to a dentry can be done call after the inode
> > unlink. This means that __fh_to_dentry() requires an extra check to
> > verify the number of links is not 0.
> >
> > The issue can be easily reproduced using xfstest generic/426, which does
> > something like:
> >
> > name_to_handle_at(&fh)
> > echo 3 > /proc/sys/vm/drop_caches
> > unlink()
> > open_by_handle_at(&fh)
> >
> > The call to open_by_handle_at() should fail, as the file doesn't exist
> > anymore.
> >
> > Cc: stable@vger.kernel.org
> > Link: http://tracker.ceph.com/issues/19958
> > Signed-off-by: Luis Henriques <lhenriques@suse.com>
> > ---
> > fs/ceph/export.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/fs/ceph/export.c b/fs/ceph/export.c
> > index e8f11fa565c5..7df550c13d7f 100644
> > --- a/fs/ceph/export.c
> > +++ b/fs/ceph/export.c
> > @@ -91,6 +91,10 @@ static struct dentry *__fh_to_dentry(struct super_block *sb, u64 ino)
> > ceph_mdsc_put_request(req);
> > if (!inode)
> > return ERR_PTR(-ESTALE);
> > + if (inode->i_nlink == 0) {
> > + iput(inode);
> > + return ERR_PTR(-ESTALE);
> > + }
> > }
>
> maybe we should do this check in MDS
Thank you for your review. Are you suggesting to do this check *only* in
the MDS? I guess that's probably a good thing to do too, but don't you
think it's a good idea to keep it on the client side as well?
Cheers,
--
Luís
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] ceph: check i_nlink while converting a file handle to dentry
2017-05-18 16:48 ` Luis Henriques
@ 2017-05-19 0:41 ` Yan, Zheng
0 siblings, 0 replies; 4+ messages in thread
From: Yan, Zheng @ 2017-05-19 0:41 UTC (permalink / raw)
To: Luis Henriques
Cc: Sage Weil, Ilya Dryomov, ceph-devel, Linux Kernel Mailing List
> On 19 May 2017, at 00:48, Luis Henriques <lhenriques@suse.com> wrote:
>
> On Thu, May 18, 2017 at 09:36:44PM +0800, Yan, Zheng wrote:
>>
>>> On 17 May 2017, at 19:21, Luis Henriques <lhenriques@suse.com> wrote:
>>>
>>> Converting a file handle to a dentry can be done call after the inode
>>> unlink. This means that __fh_to_dentry() requires an extra check to
>>> verify the number of links is not 0.
>>>
>>> The issue can be easily reproduced using xfstest generic/426, which does
>>> something like:
>>>
>>> name_to_handle_at(&fh)
>>> echo 3 > /proc/sys/vm/drop_caches
>>> unlink()
>>> open_by_handle_at(&fh)
>>>
>>> The call to open_by_handle_at() should fail, as the file doesn't exist
>>> anymore.
>>>
>>> Cc: stable@vger.kernel.org
>>> Link: http://tracker.ceph.com/issues/19958
>>> Signed-off-by: Luis Henriques <lhenriques@suse.com>
>>> ---
>>> fs/ceph/export.c | 4 ++++
>>> 1 file changed, 4 insertions(+)
>>>
>>> diff --git a/fs/ceph/export.c b/fs/ceph/export.c
>>> index e8f11fa565c5..7df550c13d7f 100644
>>> --- a/fs/ceph/export.c
>>> +++ b/fs/ceph/export.c
>>> @@ -91,6 +91,10 @@ static struct dentry *__fh_to_dentry(struct super_block *sb, u64 ino)
>>> ceph_mdsc_put_request(req);
>>> if (!inode)
>>> return ERR_PTR(-ESTALE);
>>> + if (inode->i_nlink == 0) {
>>> + iput(inode);
>>> + return ERR_PTR(-ESTALE);
>>> + }
>>> }
>>
>> maybe we should do this check in MDS
>
> Thank you for your review. Are you suggesting to do this check *only* in
> the MDS? I guess that's probably a good thing to do too, but don't you
> think it's a good idea to keep it on the client side as well?
Applied. Thanks
Yan, Zheng
>
> Cheers,
> --
> Luís
^ permalink raw reply [flat|nested] 4+ messages in thread
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2017-05-17 11:21 [PATCH] ceph: check i_nlink while converting a file handle to dentry Luis Henriques
2017-05-18 13:36 ` Yan, Zheng
2017-05-18 16:48 ` Luis Henriques
2017-05-19 0:41 ` Yan, Zheng
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