Re: [PATCH net-next 3/8] fs/quota: use nla_put_u64_64bit()

[David Miller]

From: Jan Kara 
Date: Tue, 26 Apr 2016 13:08:48 +0200

> On Tue 26-04-16 10:06:13, Nicolas Dichtel wrote:
>> Signed-off-by: Nicolas Dichtel 
> 
> OK, so I somewhat miss a description of what will this do to the netlink
> message so that I can judge whether the change is fine for the userspace
> counterpart parsing these messages. AFAIU this changes the message format
> by adding a QUOTA_NL_A_PAD field before each 64-bit field which needs an
> alignment, am I guessing right? Thus when the userspace counterpart uses
> genlmsg_parse() it should just silently ignore these attributes if I read
> the documentation right. Did I understand this correctly?

All userspace components using netlink should always ignore attributes
they do not recognize in dumps.

This is one of the most basic principles of netlink.
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Re: [PATCH net-next 3/8] fs/quota: use nla_put_u64_64bit()

[Jan Kara]

On Tue 26-04-16 14:31:58, Nicolas Dichtel wrote:
> Le 26/04/2016 13:08, Jan Kara a écrit :
> > On Tue 26-04-16 10:06:13, Nicolas Dichtel wrote:
> >> Signed-off-by: Nicolas Dichtel 
> > 
> > OK, so I somewhat miss a description of what will this do to the netlink
> > message so that I can judge whether the change is fine for the userspace
> > counterpart parsing these messages. AFAIU this changes the message format
> > by adding a QUOTA_NL_A_PAD field before each 64-bit field which needs an
> > alignment, am I guessing right? Thus when the userspace counterpart uses
> > genlmsg_parse() it should just silently ignore these attributes if I read
> > the documentation right. Did I understand this correctly?
> Yes, that's it.

OK, then feel free to add:

Acked-by: Jan Kara 

to the quota patch.

Honza

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Jan Kara 
SUSE Labs, CR
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Re: [PATCH net-next 3/8] fs/quota: use nla_put_u64_64bit()

[Nicolas Dichtel]

Le 26/04/2016 13:08, Jan Kara a écrit :
> On Tue 26-04-16 10:06:13, Nicolas Dichtel wrote:
>> Signed-off-by: Nicolas Dichtel 
> 
> OK, so I somewhat miss a description of what will this do to the netlink
> message so that I can judge whether the change is fine for the userspace
> counterpart parsing these messages. AFAIU this changes the message format
> by adding a QUOTA_NL_A_PAD field before each 64-bit field which needs an
> alignment, am I guessing right? Thus when the userspace counterpart uses
> genlmsg_parse() it should just silently ignore these attributes if I read
> the documentation right. Did I understand this correctly?
Yes, that's it.


Regards,
Nicolas
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Re: [PATCH net-next 3/8] fs/quota: use nla_put_u64_64bit()

[Jan Kara]

On Tue 26-04-16 10:06:13, Nicolas Dichtel wrote:
> Signed-off-by: Nicolas Dichtel 

OK, so I somewhat miss a description of what will this do to the netlink
message so that I can judge whether the change is fine for the userspace
counterpart parsing these messages. AFAIU this changes the message format
by adding a QUOTA_NL_A_PAD field before each 64-bit field which needs an
alignment, am I guessing right? Thus when the userspace counterpart uses
genlmsg_parse() it should just silently ignore these attributes if I read
the documentation right. Did I understand this correctly?

Honza

> ---
>  fs/quota/netlink.c | 12 +++-
>  include/uapi/linux/quota.h |  1 +
>  2 files changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/quota/netlink.c b/fs/quota/netlink.c
> index d07a2f91d858..8b252673d454 100644
> --- a/fs/quota/netlink.c
> +++ b/fs/quota/netlink.c
> @@ -47,7 +47,7 @@ void quota_send_warning(struct kqid qid, dev_t dev,
>   void *msg_head;
>   int ret;
>   int msg_size = 4 * nla_total_size(sizeof(u32)) +
> -2 * nla_total_size(sizeof(u64));
> +2 * nla_total_size_64bit(sizeof(u64));
>  
>   /* We have to allocate using GFP_NOFS as we are called from a
>* filesystem performing write and thus further recursion into
> @@ -68,8 +68,9 @@ void quota_send_warning(struct kqid qid, dev_t dev,
>   ret = nla_put_u32(skb, QUOTA_NL_A_QTYPE, qid.type);
>   if (ret)
>   goto attr_err_out;
> - ret = nla_put_u64(skb, QUOTA_NL_A_EXCESS_ID,
> -   from_kqid_munged(_user_ns, qid));
> + ret = nla_put_u64_64bit(skb, QUOTA_NL_A_EXCESS_ID,
> + from_kqid_munged(_user_ns, qid),
> + QUOTA_NL_A_PAD);
>   if (ret)
>   goto attr_err_out;
>   ret = nla_put_u32(skb, QUOTA_NL_A_WARNING, warntype);
> @@ -81,8 +82,9 @@ void quota_send_warning(struct kqid qid, dev_t dev,
>   ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MINOR, MINOR(dev));
>   if (ret)
>   goto attr_err_out;
> - ret = nla_put_u64(skb, QUOTA_NL_A_CAUSED_ID,
> -   from_kuid_munged(_user_ns, current_uid()));
> + ret = nla_put_u64_64bit(skb, QUOTA_NL_A_CAUSED_ID,
> + from_kuid_munged(_user_ns, current_uid()),
> + QUOTA_NL_A_PAD);
>   if (ret)
>   goto attr_err_out;
>   genlmsg_end(skb, msg_head);
> diff --git a/include/uapi/linux/quota.h b/include/uapi/linux/quota.h
> index 38baddb807f5..4d2489ef6f10 100644
> --- a/include/uapi/linux/quota.h
> +++ b/include/uapi/linux/quota.h
> @@ -191,6 +191,7 @@ enum {
>   QUOTA_NL_A_DEV_MAJOR,
>   QUOTA_NL_A_DEV_MINOR,
>   QUOTA_NL_A_CAUSED_ID,
> + QUOTA_NL_A_PAD,
>   __QUOTA_NL_A_MAX,
>  };
>  #define QUOTA_NL_A_MAX (__QUOTA_NL_A_MAX - 1)
> -- 
> 2.8.1
> 
> 
-- 
Jan Kara 
SUSE Labs, CR
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[PATCH net-next 3/8] fs/quota: use nla_put_u64_64bit()

[Nicolas Dichtel]

Signed-off-by: Nicolas Dichtel 
---
 fs/quota/netlink.c | 12 +++-
 include/uapi/linux/quota.h |  1 +
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/fs/quota/netlink.c b/fs/quota/netlink.c
index d07a2f91d858..8b252673d454 100644
--- a/fs/quota/netlink.c
+++ b/fs/quota/netlink.c
@@ -47,7 +47,7 @@ void quota_send_warning(struct kqid qid, dev_t dev,
void *msg_head;
int ret;
int msg_size = 4 * nla_total_size(sizeof(u32)) +
-  2 * nla_total_size(sizeof(u64));
+  2 * nla_total_size_64bit(sizeof(u64));
 
/* We have to allocate using GFP_NOFS as we are called from a
 * filesystem performing write and thus further recursion into
@@ -68,8 +68,9 @@ void quota_send_warning(struct kqid qid, dev_t dev,
ret = nla_put_u32(skb, QUOTA_NL_A_QTYPE, qid.type);
if (ret)
goto attr_err_out;
-   ret = nla_put_u64(skb, QUOTA_NL_A_EXCESS_ID,
- from_kqid_munged(_user_ns, qid));
+   ret = nla_put_u64_64bit(skb, QUOTA_NL_A_EXCESS_ID,
+   from_kqid_munged(_user_ns, qid),
+   QUOTA_NL_A_PAD);
if (ret)
goto attr_err_out;
ret = nla_put_u32(skb, QUOTA_NL_A_WARNING, warntype);
@@ -81,8 +82,9 @@ void quota_send_warning(struct kqid qid, dev_t dev,
ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MINOR, MINOR(dev));
if (ret)
goto attr_err_out;
-   ret = nla_put_u64(skb, QUOTA_NL_A_CAUSED_ID,
- from_kuid_munged(_user_ns, current_uid()));
+   ret = nla_put_u64_64bit(skb, QUOTA_NL_A_CAUSED_ID,
+   from_kuid_munged(_user_ns, current_uid()),
+   QUOTA_NL_A_PAD);
if (ret)
goto attr_err_out;
genlmsg_end(skb, msg_head);
diff --git a/include/uapi/linux/quota.h b/include/uapi/linux/quota.h
index 38baddb807f5..4d2489ef6f10 100644
--- a/include/uapi/linux/quota.h
+++ b/include/uapi/linux/quota.h
@@ -191,6 +191,7 @@ enum {
QUOTA_NL_A_DEV_MAJOR,
QUOTA_NL_A_DEV_MINOR,
QUOTA_NL_A_CAUSED_ID,
+   QUOTA_NL_A_PAD,
__QUOTA_NL_A_MAX,
 };
 #define QUOTA_NL_A_MAX (__QUOTA_NL_A_MAX - 1)
-- 
2.8.1

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