[PATCH net-next 2/3] mpls: consistently use u8 to store number of labels

[PATCH net-next 2/3] mpls: consistently use u8 to store number of labels

[Roopa Prabhu]

From: Roopa Prabhu <roopa@cumulusnetworks.com>

change all types representing number of labels to u8
to be consistent.

This also changes labels to u8 in the light weight
mpls_tunnel_encap structure. This is because the
light weight mpls iptunnel code shares some of the label
encoding functions like nla_get/put_labels with the af_mpls
code.

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
---
 include/net/mpls_iptunnel.h |    2 +-
 net/mpls/af_mpls.c          |   10 +++++-----
 net/mpls/internal.h         |    2 +-
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/include/net/mpls_iptunnel.h b/include/net/mpls_iptunnel.h
index 4757997..179253f 100644
--- a/include/net/mpls_iptunnel.h
+++ b/include/net/mpls_iptunnel.h
@@ -18,7 +18,7 @@
 
 struct mpls_iptunnel_encap {
 	u32	label[MAX_NEW_LABELS];
-	u32	labels;
+	u8	labels;
 };
 
 static inline struct mpls_iptunnel_encap *mpls_lwtunnel_encap(struct lwtunnel_state *lwtstate)
diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index cf86e9d..eb089ef 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -243,11 +243,11 @@ static const struct nla_policy rtm_mpls_policy[RTA_MAX+1] = {
 struct mpls_route_config {
 	u32			rc_protocol;
 	u32			rc_ifindex;
-	u16			rc_via_table;
-	u16			rc_via_alen;
+	u8			rc_via_table;
+	u8			rc_via_alen;
 	u8			rc_via[MAX_VIA_ALEN];
+	u8			rc_output_labels;
 	u32			rc_label;
-	u32			rc_output_labels;
 	u32			rc_output_label[MAX_NEW_LABELS];
 	u32			rc_nlflags;
 	enum mpls_payload_type	rc_payload_type;
@@ -751,7 +751,7 @@ int nla_put_labels(struct sk_buff *skb, int attrtype,
 EXPORT_SYMBOL_GPL(nla_put_labels);
 
 int nla_get_labels(const struct nlattr *nla,
-		   u32 max_labels, u32 *labels, u32 label[])
+		   u32 max_labels, u8 *labels, u32 label[])
 {
 	unsigned len = nla_len(nla);
 	unsigned nla_labels;
@@ -859,7 +859,7 @@ static int rtm_to_route_config(struct sk_buff *skb,  struct nlmsghdr *nlh,
 			break;
 		case RTA_DST:
 		{
-			u32 label_count;
+			u8 label_count;
 			if (nla_get_labels(nla, 1, &label_count,
 					   &cfg->rc_label))
 				goto errout;
diff --git a/net/mpls/internal.h b/net/mpls/internal.h
index f05e2e8..f5dafcaf 100644
--- a/net/mpls/internal.h
+++ b/net/mpls/internal.h
@@ -87,7 +87,7 @@ static inline struct mpls_entry_decoded mpls_entry_decode(struct mpls_shim_hdr *
 
 int nla_put_labels(struct sk_buff *skb, int attrtype,  u8 labels,
 		   const u32 label[]);
-int nla_get_labels(const struct nlattr *nla, u32 max_labels, u32 *labels,
+int nla_get_labels(const struct nlattr *nla, u32 max_labels, u8 *labels,
 		   u32 label[]);
 bool mpls_output_possible(const struct net_device *dev);
 unsigned int mpls_dev_mtu(const struct net_device *dev);
-- 
1.7.10.4

Re: [PATCH net-next 2/3] mpls: consistently use u8 to store number of labels

[Robert Shearman]

On 11/08/15 22:45, Roopa Prabhu wrote:
> From: Roopa Prabhu <roopa@cumulusnetworks.com>
>
> change all types representing number of labels to u8
> to be consistent.
>
> This also changes labels to u8 in the light weight
> mpls_tunnel_encap structure. This is because the
> light weight mpls iptunnel code shares some of the label
> encoding functions like nla_get/put_labels with the af_mpls
> code.
>
> Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
> ---
...
> @@ -243,11 +243,11 @@ static const struct nla_policy rtm_mpls_policy[RTA_MAX+1] = {
>   struct mpls_route_config {
>   	u32			rc_protocol;
>   	u32			rc_ifindex;
> -	u16			rc_via_table;
> -	u16			rc_via_alen;
> +	u8			rc_via_table;
> +	u8			rc_via_alen;

IMHO, it would be better to make rc_via_alen an int to avoid overflow 
which could cause false negatives in this check on the RTA_VIA attribute:

			if (cfg->rc_via_alen > MAX_VIA_ALEN)
				goto errout;

...
>   	u8			rc_via[MAX_VIA_ALEN];
> +	u8			rc_output_labels;
>   	u32			rc_label;
> -	u32			rc_output_labels;
>   	u32			rc_output_label[MAX_NEW_LABELS];
>   	u32			rc_nlflags;
>   	enum mpls_payload_type	rc_payload_type;
> @@ -751,7 +751,7 @@ int nla_put_labels(struct sk_buff *skb, int attrtype,
>   EXPORT_SYMBOL_GPL(nla_put_labels);
>
>   int nla_get_labels(const struct nlattr *nla,
> -		   u32 max_labels, u32 *labels, u32 label[])
> +		   u32 max_labels, u8 *labels, u32 label[])

How about making max_labels a u8? That would make it even more 
consistent and avoids any problem of overflow in the number of labels.

Thanks,
Rob

Re: [PATCH net-next 2/3] mpls: consistently use u8 to store number of labels

[roopa]

On 8/12/15, 12:17 PM, Robert Shearman wrote:
> On 11/08/15 22:45, Roopa Prabhu wrote:
>> From: Roopa Prabhu <roopa@cumulusnetworks.com>
>>
>> change all types representing number of labels to u8
>> to be consistent.
>>
>> This also changes labels to u8 in the light weight
>> mpls_tunnel_encap structure. This is because the
>> light weight mpls iptunnel code shares some of the label
>> encoding functions like nla_get/put_labels with the af_mpls
>> code.
>>
>> Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
>> ---
> ...
>> @@ -243,11 +243,11 @@ static const struct nla_policy 
>> rtm_mpls_policy[RTA_MAX+1] = {
>>   struct mpls_route_config {
>>       u32            rc_protocol;
>>       u32            rc_ifindex;
>> -    u16            rc_via_table;
>> -    u16            rc_via_alen;
>> +    u8            rc_via_table;
>> +    u8            rc_via_alen;
>
> IMHO, it would be better to make rc_via_alen an int to avoid overflow 
> which could cause false negatives in this check on the RTA_VIA attribute:
>
>             if (cfg->rc_via_alen > MAX_VIA_ALEN)
>                 goto errout;
>

ok,
> ...
>>       u8            rc_via[MAX_VIA_ALEN];
>> +    u8            rc_output_labels;
>>       u32            rc_label;
>> -    u32            rc_output_labels;
>>       u32            rc_output_label[MAX_NEW_LABELS];
>>       u32            rc_nlflags;
>>       enum mpls_payload_type    rc_payload_type;
>> @@ -751,7 +751,7 @@ int nla_put_labels(struct sk_buff *skb, int 
>> attrtype,
>>   EXPORT_SYMBOL_GPL(nla_put_labels);
>>
>>   int nla_get_labels(const struct nlattr *nla,
>> -           u32 max_labels, u32 *labels, u32 label[])
>> +           u32 max_labels, u8 *labels, u32 label[])
>
> How about making max_labels a u8? That would make it even more 
> consistent and avoids any problem of overflow in the number of labels.
>
yes, I did want to change max_labels to u8. will do in v2.

thanks,
Roopa