ether: check the first segment length on SW VLAN insertion
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Message ID 1590589902-31034-1-git-send-email-arybchenko@solarflare.com
State New
Delegated to: Ferruh Yigit
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Series
  • ether: check the first segment length on SW VLAN insertion
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Commit Message

Andrew Rybchenko May 27, 2020, 2:31 p.m. UTC
SW VLAN insertion relies on Ethernet addresses location in contigous
memory (do not split across mbuf segments). There is no any formal
requirements on data location and mbuf structure which guarantee it.
So, check it explicitly to avoid corrupted packets if the condition
is violated. Typically software VLAN insertion is done on Tx prepare
stage and application will get indication that the packet is invalid
and cannot be transmitted.

Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>
---
 lib/librte_net/rte_ether.h | 4 ++++
 1 file changed, 4 insertions(+)

Comments

Stephen Hemminger May 29, 2020, 5:43 a.m. UTC | #1
On Wed, 27 May 2020 15:31:41 +0100
Andrew Rybchenko <arybchenko@solarflare.com> wrote:

> SW VLAN insertion relies on Ethernet addresses location in contigous
> memory (do not split across mbuf segments). There is no any formal
> requirements on data location and mbuf structure which guarantee it.
> So, check it explicitly to avoid corrupted packets if the condition
> is violated. Typically software VLAN insertion is done on Tx prepare
> stage and application will get indication that the packet is invalid
> and cannot be transmitted.
> 
> Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>
> ---
>  lib/librte_net/rte_ether.h | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/lib/librte_net/rte_ether.h b/lib/librte_net/rte_ether.h
> index 0ae4e75b6c..d7c076bba8 100644
> --- a/lib/librte_net/rte_ether.h
> +++ b/lib/librte_net/rte_ether.h
> @@ -357,6 +357,10 @@ static inline int rte_vlan_insert(struct rte_mbuf **m)
>  	if (!RTE_MBUF_DIRECT(*m) || rte_mbuf_refcnt_read(*m) > 1)
>  		return -EINVAL;
>  
> +	/* Can't insert header if the first segment is too short */
> +	if (rte_pktmbuf_data_len(*m) < 2 * RTE_ETHER_ADDR_LEN)
> +		return -EINVAL;

Looks good, but you could also make it handle the fragment case with:

diff --git a/lib/librte_net/rte_ether.h b/lib/librte_net/rte_ether.h
index 0ae4e75b6c58..4d0e310a4fac 100644
--- a/lib/librte_net/rte_ether.h
+++ b/lib/librte_net/rte_ether.h
@@ -350,14 +350,18 @@ static inline int rte_vlan_strip(struct rte_mbuf *m)
  */
 static inline int rte_vlan_insert(struct rte_mbuf **m)
 {
-	struct rte_ether_hdr *oh, *nh;
+	struct rte_ether_hdr *nh, tmp;
+	const struct rte_ether_hdr *oh;
 	struct rte_vlan_hdr *vh;
 
 	/* Can't insert header if mbuf is shared */
 	if (!RTE_MBUF_DIRECT(*m) || rte_mbuf_refcnt_read(*m) > 1)
 		return -EINVAL;
 
-	oh = rte_pktmbuf_mtod(*m, struct rte_ether_hdr *);
+	oh = rte_pktmbuf_read(*m, 0, sizeof(*oh), &tmp);
+	if (unlikely(oh == NULL))
+		return -EINVAL;
+
 	nh = (struct rte_ether_hdr *)
 		rte_pktmbuf_prepend(*m, sizeof(struct rte_vlan_hdr));
 	if (nh == NULL)
Andrew Rybchenko June 25, 2020, 12:27 p.m. UTC | #2
On 5/29/20 8:43 AM, Stephen Hemminger wrote:
> On Wed, 27 May 2020 15:31:41 +0100
> Andrew Rybchenko <arybchenko@solarflare.com> wrote:
> 
>> SW VLAN insertion relies on Ethernet addresses location in contigous
>> memory (do not split across mbuf segments). There is no any formal
>> requirements on data location and mbuf structure which guarantee it.
>> So, check it explicitly to avoid corrupted packets if the condition
>> is violated. Typically software VLAN insertion is done on Tx prepare
>> stage and application will get indication that the packet is invalid
>> and cannot be transmitted.
>>
>> Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>
>> ---
>>  lib/librte_net/rte_ether.h | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/lib/librte_net/rte_ether.h b/lib/librte_net/rte_ether.h
>> index 0ae4e75b6c..d7c076bba8 100644
>> --- a/lib/librte_net/rte_ether.h
>> +++ b/lib/librte_net/rte_ether.h
>> @@ -357,6 +357,10 @@ static inline int rte_vlan_insert(struct rte_mbuf **m)
>>  	if (!RTE_MBUF_DIRECT(*m) || rte_mbuf_refcnt_read(*m) > 1)
>>  		return -EINVAL;
>>  
>> +	/* Can't insert header if the first segment is too short */
>> +	if (rte_pktmbuf_data_len(*m) < 2 * RTE_ETHER_ADDR_LEN)
>> +		return -EINVAL;
> 
> Looks good, but you could also make it handle the fragment case with:
> 
> diff --git a/lib/librte_net/rte_ether.h b/lib/librte_net/rte_ether.h
> index 0ae4e75b6c58..4d0e310a4fac 100644
> --- a/lib/librte_net/rte_ether.h
> +++ b/lib/librte_net/rte_ether.h
> @@ -350,14 +350,18 @@ static inline int rte_vlan_strip(struct rte_mbuf *m)
>   */
>  static inline int rte_vlan_insert(struct rte_mbuf **m)
>  {
> -	struct rte_ether_hdr *oh, *nh;
> +	struct rte_ether_hdr *nh, tmp;
> +	const struct rte_ether_hdr *oh;
>  	struct rte_vlan_hdr *vh;
>  
>  	/* Can't insert header if mbuf is shared */
>  	if (!RTE_MBUF_DIRECT(*m) || rte_mbuf_refcnt_read(*m) > 1)
>  		return -EINVAL;
>  
> -	oh = rte_pktmbuf_mtod(*m, struct rte_ether_hdr *);
> +	oh = rte_pktmbuf_read(*m, 0, sizeof(*oh), &tmp);
> +	if (unlikely(oh == NULL))
> +		return -EINVAL;
> +
>  	nh = (struct rte_ether_hdr *)
>  		rte_pktmbuf_prepend(*m, sizeof(struct rte_vlan_hdr));
>  	if (nh == NULL)
> 

It is more complicated since memmove() below should be
rewritten  in a similar way as rte_pktmbuf_read(), but
write. I'm not sure it worse the effort.

Patch
diff mbox series

diff --git a/lib/librte_net/rte_ether.h b/lib/librte_net/rte_ether.h
index 0ae4e75b6c..d7c076bba8 100644
--- a/lib/librte_net/rte_ether.h
+++ b/lib/librte_net/rte_ether.h
@@ -357,6 +357,10 @@  static inline int rte_vlan_insert(struct rte_mbuf **m)
 	if (!RTE_MBUF_DIRECT(*m) || rte_mbuf_refcnt_read(*m) > 1)
 		return -EINVAL;
 
+	/* Can't insert header if the first segment is too short */
+	if (rte_pktmbuf_data_len(*m) < 2 * RTE_ETHER_ADDR_LEN)
+		return -EINVAL;
+
 	oh = rte_pktmbuf_mtod(*m, struct rte_ether_hdr *);
 	nh = (struct rte_ether_hdr *)
 		rte_pktmbuf_prepend(*m, sizeof(struct rte_vlan_hdr));