Re: [PATCH] staging: erofs: harden inode lookup for 32-bit platforms
Hi Dan,
On 2018/10/11 19:12, Dan Carpenter wrote:
> On Thu, Oct 11, 2018 at 06:49:57PM +0800, Gao Xiang wrote:
>> Hi Dan,
>>
>> On 2018/10/11 18:18, Dan Carpenter wrote:
>>> On Thu, Oct 11, 2018 at 05:46:26PM +0800, Gao Xiang wrote:
On 2018/10/11 16:44, Dan Carpenter wrote:
> On Tue, Oct 09, 2018 at 10:07:13PM +0800, Gao Xiang wrote:
>> This patch introduces inode hash function, test and set callbacks,
>> and iget5_locked to find the right inode for 32-bit platforms.
>>
>
> The way I read this changelog, we're trying to deal with corrupt file
> systems? Is that correct? Presumably in the current code it could lead
> to a Oops or something?
No, this commit isn't trying to deal with corrupt file systems.
In EROFS, the nid is not continuous and it represents the inode offset
inode offset = nid * 32.
Therefore the nid is 64-bit both for 32-bit and 64-bit platforms. However,
i_ino is 'unsigned long', which means for 32-bit platforms, i_ino is not
enough
to contain the nid.
Therefore, we should use iget5_locked for this case.
>>>
>>> I guess what I'm saying is, what are the user visible effects of this
>>> patch? It's hard for me to tell from the patch description. Could you
>>> please re-write the description and send a v2?
>>
>> Sorry for my just hurry reply. It seems I really misunderstood your point :-(
>>
>> If all nids are less than 32-bit, the user will see the correct inode/nid
>> number
>> for all 32-bit platforms, but if some nids are greater than 32-bit, it could
>> be
>> collisions without this patch for 32-bit platforms.
>>
>> This patch switch the inode number by XOR the high 32-bit and the low 32-bit,
>> use customized tester to avoid collisions for 32-bit platforms.
>>
>> I will send v2 to fix the commit message...but it seems Greg is already
>> merged in
>> https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git/commit/?h=staging-testing&id=2abd7814138774eb56319e9dcc0abd08ece45424
>>
>
> Oh. Then that's fine then. If Greg already merged it, then it's too
> late to change. Thanks for the explanation, though.
I appended the v2 patch in the end of this reply for reference...
Thanks,
Gao Xiang
>
> regards,
> dan carpenter
>
>From 175eb3f1c6e1cddf8292853ab0fb7644320c3ae2 Mon Sep 17 00:00:00 2001
From: Gao Xiang
Date: Mon, 1 Oct 2018 12:32:55 +0800
Subject: [PATCH v2] staging: erofs: harden inode lookup for 32-bit platforms
Each erofs inode has a unique 64-bit nid to distinguish from others.
However, the inode number is usually defined as `unsigned long',
which means some collisions could happen if we directly use iget_locked
for 32-bit platforms.
Therefore, this patch introduces a inode hash function, test and set
callbacks, and iget5_locked to avoid potential collisions
for 32-bit platforms.
In addition, if the value of a nid is greater than 32-bit, users from
32-bit platforms will see XOR-ed inode numbers after this patch.
Reviewed-by: Chao Yu
Signed-off-by: Gao Xiang
---
change log v2:
- add more infos to the commit message as pointed out by Dan Carpenter.
Thanks,
Gao Xiang
drivers/staging/erofs/inode.c| 37 -
drivers/staging/erofs/internal.h | 9 +
2 files changed, 45 insertions(+), 1 deletion(-)
diff --git a/drivers/staging/erofs/inode.c b/drivers/staging/erofs/inode.c
index da8693a7c3d3..04c61a9d7b76 100644
--- a/drivers/staging/erofs/inode.c
+++ b/drivers/staging/erofs/inode.c
@@ -232,10 +232,45 @@ static int fill_inode(struct inode *inode, int isdir)
return err;
}
+/*
+ * erofs nid is 64bits, but i_ino is 'unsigned long', therefore
+ * we should do more for 32-bit platform to find the right inode.
+ */
+#if BITS_PER_LONG == 32
+static int erofs_ilookup_test_actor(struct inode *inode, void *opaque)
+{
+ const erofs_nid_t nid = *(erofs_nid_t *)opaque;
+
+ return EROFS_V(inode)->nid == nid;
+}
+
+static int erofs_iget_set_actor(struct inode *inode, void *opaque)
+{
+ const erofs_nid_t nid = *(erofs_nid_t *)opaque;
+
+ inode->i_ino = erofs_inode_hash(nid);
+ return 0;
+}
+#endif
+
+static inline struct inode *erofs_iget_locked(struct super_block *sb,
+ erofs_nid_t nid)
+{
+ const unsigned long hashval = erofs_inode_hash(nid);
+
+#if BITS_PER_LONG >= 64
+ /* it is safe to use iget_locked for >= 64-bit platform */
+ return iget_locked(sb, hashval);
+#else
+ return iget5_locked(sb, hashval, erofs_ilookup_test_actor,
+ erofs_iget_set_actor, &nid);
+#endif
+}
+
struct inode *erofs_iget(struct super_block *sb,
erofs_nid_t nid, bool isdir)
{
- struct inode *inode = iget_locked(sb, nid);
+ struct inode *inode = erofs_iget_locked(sb, nid);
if (unlikely(inode == NULL))
return ERR_PTR(-ENOMEM);
diff --git a/drivers/staging/erofs/internal.h b/drivers/sta
Re: [PATCH] staging: erofs: harden inode lookup for 32-bit platforms
On Thu, Oct 11, 2018 at 06:49:57PM +0800, Gao Xiang wrote: > Hi Dan, > > On 2018/10/11 18:18, Dan Carpenter wrote: > > On Thu, Oct 11, 2018 at 05:46:26PM +0800, Gao Xiang wrote: > >> > >> > >> On 2018/10/11 16:44, Dan Carpenter wrote: > >>> On Tue, Oct 09, 2018 at 10:07:13PM +0800, Gao Xiang wrote: > This patch introduces inode hash function, test and set callbacks, > and iget5_locked to find the right inode for 32-bit platforms. > > >>> > >>> The way I read this changelog, we're trying to deal with corrupt file > >>> systems? Is that correct? Presumably in the current code it could lead > >>> to a Oops or something? > >> > >> No, this commit isn't trying to deal with corrupt file systems. > >> In EROFS, the nid is not continuous and it represents the inode offset > >> inode offset = nid * 32. > >> Therefore the nid is 64-bit both for 32-bit and 64-bit platforms. However, > >> i_ino is 'unsigned long', which means for 32-bit platforms, i_ino is not > >> enough > >> to contain the nid. > >> > >> Therefore, we should use iget5_locked for this case. > > > > I guess what I'm saying is, what are the user visible effects of this > > patch? It's hard for me to tell from the patch description. Could you > > please re-write the description and send a v2? > > Sorry for my just hurry reply. It seems I really misunderstood your point :-( > > If all nids are less than 32-bit, the user will see the correct inode/nid > number > for all 32-bit platforms, but if some nids are greater than 32-bit, it could > be > collisions without this patch for 32-bit platforms. > > This patch switch the inode number by XOR the high 32-bit and the low 32-bit, > use customized tester to avoid collisions for 32-bit platforms. > > I will send v2 to fix the commit message...but it seems Greg is already > merged in > https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git/commit/?h=staging-testing&id=2abd7814138774eb56319e9dcc0abd08ece45424 > Oh. Then that's fine then. If Greg already merged it, then it's too late to change. Thanks for the explanation, though. regards, dan carpenter ___ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
Re: [PATCH] staging: erofs: harden inode lookup for 32-bit platforms
Hi Dan, On 2018/10/11 18:18, Dan Carpenter wrote: > On Thu, Oct 11, 2018 at 05:46:26PM +0800, Gao Xiang wrote: >> >> >> On 2018/10/11 16:44, Dan Carpenter wrote: >>> On Tue, Oct 09, 2018 at 10:07:13PM +0800, Gao Xiang wrote: This patch introduces inode hash function, test and set callbacks, and iget5_locked to find the right inode for 32-bit platforms. >>> >>> The way I read this changelog, we're trying to deal with corrupt file >>> systems? Is that correct? Presumably in the current code it could lead >>> to a Oops or something? >> >> No, this commit isn't trying to deal with corrupt file systems. >> In EROFS, the nid is not continuous and it represents the inode offset >> inode offset = nid * 32. >> Therefore the nid is 64-bit both for 32-bit and 64-bit platforms. However, >> i_ino is 'unsigned long', which means for 32-bit platforms, i_ino is not >> enough >> to contain the nid. >> >> Therefore, we should use iget5_locked for this case. > > I guess what I'm saying is, what are the user visible effects of this > patch? It's hard for me to tell from the patch description. Could you > please re-write the description and send a v2? Sorry for my just hurry reply. It seems I really misunderstood your point :-( If all nids are less than 32-bit, the user will see the correct inode/nid number for all 32-bit platforms, but if some nids are greater than 32-bit, it could be collisions without this patch for 32-bit platforms. This patch switch the inode number by XOR the high 32-bit and the low 32-bit, use customized tester to avoid collisions for 32-bit platforms. I will send v2 to fix the commit message...but it seems Greg is already merged in https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git/commit/?h=staging-testing&id=2abd7814138774eb56319e9dcc0abd08ece45424 Thanks, Gao Xiang > > regards, > dan carpenter > ___ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
Re: [PATCH] staging: erofs: harden inode lookup for 32-bit platforms
On Thu, Oct 11, 2018 at 05:46:26PM +0800, Gao Xiang wrote: > > > On 2018/10/11 16:44, Dan Carpenter wrote: > > On Tue, Oct 09, 2018 at 10:07:13PM +0800, Gao Xiang wrote: > >> This patch introduces inode hash function, test and set callbacks, > >> and iget5_locked to find the right inode for 32-bit platforms. > >> > > > > The way I read this changelog, we're trying to deal with corrupt file > > systems? Is that correct? Presumably in the current code it could lead > > to a Oops or something? > > No, this commit isn't trying to deal with corrupt file systems. > In EROFS, the nid is not continuous and it represents the inode offset > inode offset = nid * 32. > Therefore the nid is 64-bit both for 32-bit and 64-bit platforms. However, > i_ino is 'unsigned long', which means for 32-bit platforms, i_ino is not > enough > to contain the nid. > > Therefore, we should use iget5_locked for this case. I guess what I'm saying is, what are the user visible effects of this patch? It's hard for me to tell from the patch description. Could you please re-write the description and send a v2? regards, dan carpenter ___ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
Re: [PATCH] staging: erofs: harden inode lookup for 32-bit platforms
On 2018/10/11 16:44, Dan Carpenter wrote: > On Tue, Oct 09, 2018 at 10:07:13PM +0800, Gao Xiang wrote: >> This patch introduces inode hash function, test and set callbacks, >> and iget5_locked to find the right inode for 32-bit platforms. >> > > The way I read this changelog, we're trying to deal with corrupt file > systems? Is that correct? Presumably in the current code it could lead > to a Oops or something? No, this commit isn't trying to deal with corrupt file systems. In EROFS, the nid is not continuous and it represents the inode offset inode offset = nid * 32. Therefore the nid is 64-bit both for 32-bit and 64-bit platforms. However, i_ino is 'unsigned long', which means for 32-bit platforms, i_ino is not enough to contain the nid. Therefore, we should use iget5_locked for this case. > > regards, > dan carpenter > ___ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
Re: [PATCH] staging: erofs: harden inode lookup for 32-bit platforms
On Tue, Oct 09, 2018 at 10:07:13PM +0800, Gao Xiang wrote: > This patch introduces inode hash function, test and set callbacks, > and iget5_locked to find the right inode for 32-bit platforms. > The way I read this changelog, we're trying to deal with corrupt file systems? Is that correct? Presumably in the current code it could lead to a Oops or something? regards, dan carpenter ___ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
[PATCH] staging: erofs: harden inode lookup for 32-bit platforms
This patch introduces inode hash function, test and set callbacks,
and iget5_locked to find the right inode for 32-bit platforms.
Reviewed-by: Chao Yu
Signed-off-by: Gao Xiang
---
The patch has been previewed in the linux-erofs mailing list, submit to
the staging mailing list for linux-4.20.
Thanks,
Gao Xiang
drivers/staging/erofs/inode.c| 37 -
drivers/staging/erofs/internal.h | 9 +
2 files changed, 45 insertions(+), 1 deletion(-)
diff --git a/drivers/staging/erofs/inode.c b/drivers/staging/erofs/inode.c
index da8693a7c3d3..04c61a9d7b76 100644
--- a/drivers/staging/erofs/inode.c
+++ b/drivers/staging/erofs/inode.c
@@ -232,10 +232,45 @@ static int fill_inode(struct inode *inode, int isdir)
return err;
}
+/*
+ * erofs nid is 64bits, but i_ino is 'unsigned long', therefore
+ * we should do more for 32-bit platform to find the right inode.
+ */
+#if BITS_PER_LONG == 32
+static int erofs_ilookup_test_actor(struct inode *inode, void *opaque)
+{
+ const erofs_nid_t nid = *(erofs_nid_t *)opaque;
+
+ return EROFS_V(inode)->nid == nid;
+}
+
+static int erofs_iget_set_actor(struct inode *inode, void *opaque)
+{
+ const erofs_nid_t nid = *(erofs_nid_t *)opaque;
+
+ inode->i_ino = erofs_inode_hash(nid);
+ return 0;
+}
+#endif
+
+static inline struct inode *erofs_iget_locked(struct super_block *sb,
+ erofs_nid_t nid)
+{
+ const unsigned long hashval = erofs_inode_hash(nid);
+
+#if BITS_PER_LONG >= 64
+ /* it is safe to use iget_locked for >= 64-bit platform */
+ return iget_locked(sb, hashval);
+#else
+ return iget5_locked(sb, hashval, erofs_ilookup_test_actor,
+ erofs_iget_set_actor, &nid);
+#endif
+}
+
struct inode *erofs_iget(struct super_block *sb,
erofs_nid_t nid, bool isdir)
{
- struct inode *inode = iget_locked(sb, nid);
+ struct inode *inode = erofs_iget_locked(sb, nid);
if (unlikely(inode == NULL))
return ERR_PTR(-ENOMEM);
diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
index 5096b27bcf0d..57575c7f5635 100644
--- a/drivers/staging/erofs/internal.h
+++ b/drivers/staging/erofs/internal.h
@@ -517,6 +517,15 @@ erofs_get_inline_page(struct inode *inode,
}
/* inode.c */
+static inline unsigned long erofs_inode_hash(erofs_nid_t nid)
+{
+#if BITS_PER_LONG == 32
+ return (nid >> 32) ^ (nid & 0x);
+#else
+ return nid;
+#endif
+}
+
extern struct inode *erofs_iget(struct super_block *sb,
erofs_nid_t nid, bool dir);
--
2.14.4
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