[Qemu-devel] [PATCH] net/vmxnet3: Refine l2 header validation

[Qemu-devel] [PATCH] net/vmxnet3: Refine l2 header validation

[Shmulik Ladkani]

From: Dana Rubin <dana.rubin@ravellosystems.com>

Validation of l2 header length assumed minimal packet size as
eth_header + 2 * vlan_header regardless of the actual protocol.

This caused crash for valid non-IP packets shorter than 22 bytes, as
'tx_pkt->packet_type' hasn't been assigned for such packets, and
'vmxnet3_on_tx_done_update_stats()' expects it to be properly set.

Refine header length validation in 'vmxnet_tx_pkt_parse_headers'.
Check its return value during packet processing flow.

As a side effect, in case IPv4 and IPv6 header validation failure,
corrupt packets will be dropped.

Signed-off-by: Dana Rubin <dana.rubin@ravellosystems.com>
Signed-off-by: Shmulik Ladkani <shmulik.ladkani@ravellosystems.com>
---
 hw/net/vmxnet3.c       |  4 +---
 hw/net/vmxnet_tx_pkt.c | 19 ++++++++++++++++---
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/hw/net/vmxnet3.c b/hw/net/vmxnet3.c
index 59b06b8..f37297f 100644
--- a/hw/net/vmxnet3.c
+++ b/hw/net/vmxnet3.c
@@ -729,9 +729,7 @@ static void vmxnet3_process_tx_queue(VMXNET3State *s, int qidx)
         }
 
         if (txd.eop) {
-            if (!s->skip_current_tx_pkt) {
-                vmxnet_tx_pkt_parse(s->tx_pkt);
-
+            if (!s->skip_current_tx_pkt && vmxnet_tx_pkt_parse(s->tx_pkt)) {
                 if (s->needs_vlan) {
                     vmxnet_tx_pkt_setup_vlan_header(s->tx_pkt, s->tci);
                 }
diff --git a/hw/net/vmxnet_tx_pkt.c b/hw/net/vmxnet_tx_pkt.c
index f7344c4..eb88ddf 100644
--- a/hw/net/vmxnet_tx_pkt.c
+++ b/hw/net/vmxnet_tx_pkt.c
@@ -142,11 +142,24 @@ static bool vmxnet_tx_pkt_parse_headers(struct VmxnetTxPkt *pkt)
 
     bytes_read = iov_to_buf(pkt->raw, pkt->raw_frags, 0, l2_hdr->iov_base,
                             ETH_MAX_L2_HDR_LEN);
-    if (bytes_read < ETH_MAX_L2_HDR_LEN) {
+    if (bytes_read < sizeof(struct eth_header)) {
+        l2_hdr->iov_len = 0;
+        return false;
+    }
+
+    l2_hdr->iov_len = sizeof(struct eth_header);
+    switch (be16_to_cpu(PKT_GET_ETH_HDR(l2_hdr->iov_base)->h_proto)) {
+    case ETH_P_VLAN:
+        l2_hdr->iov_len += sizeof(struct vlan_header);
+        break;
+    case ETH_P_DVLAN:
+        l2_hdr->iov_len += 2 * sizeof(struct vlan_header);
+        break;
+    }
+
+    if (bytes_read < l2_hdr->iov_len) {
         l2_hdr->iov_len = 0;
         return false;
-    } else {
-        l2_hdr->iov_len = eth_get_l2_hdr_length(l2_hdr->iov_base);
     }
 
     l3_proto = eth_get_l3_proto(l2_hdr->iov_base, l2_hdr->iov_len);
-- 
1.9.1

Re: [Qemu-devel] [PATCH] net/vmxnet3: Refine l2 header validation

[Dmitry Fleytman]

ACK.

> On Aug 18, 2015, at 02:45 AM, Shmulik Ladkani <shmulik.ladkani@ravellosystems.com> wrote:
> 
> From: Dana Rubin <dana.rubin@ravellosystems.com>
> 
> Validation of l2 header length assumed minimal packet size as
> eth_header + 2 * vlan_header regardless of the actual protocol.
> 
> This caused crash for valid non-IP packets shorter than 22 bytes, as
> 'tx_pkt->packet_type' hasn't been assigned for such packets, and
> 'vmxnet3_on_tx_done_update_stats()' expects it to be properly set.
> 
> Refine header length validation in 'vmxnet_tx_pkt_parse_headers'.
> Check its return value during packet processing flow.
> 
> As a side effect, in case IPv4 and IPv6 header validation failure,
> corrupt packets will be dropped.
> 
> Signed-off-by: Dana Rubin <dana.rubin@ravellosystems.com>
> Signed-off-by: Shmulik Ladkani <shmulik.ladkani@ravellosystems.com>
> ---
> hw/net/vmxnet3.c       |  4 +---
> hw/net/vmxnet_tx_pkt.c | 19 ++++++++++++++++---
> 2 files changed, 17 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/net/vmxnet3.c b/hw/net/vmxnet3.c
> index 59b06b8..f37297f 100644
> --- a/hw/net/vmxnet3.c
> +++ b/hw/net/vmxnet3.c
> @@ -729,9 +729,7 @@ static void vmxnet3_process_tx_queue(VMXNET3State *s, int qidx)
>         }
> 
>         if (txd.eop) {
> -            if (!s->skip_current_tx_pkt) {
> -                vmxnet_tx_pkt_parse(s->tx_pkt);
> -
> +            if (!s->skip_current_tx_pkt && vmxnet_tx_pkt_parse(s->tx_pkt)) {
>                 if (s->needs_vlan) {
>                     vmxnet_tx_pkt_setup_vlan_header(s->tx_pkt, s->tci);
>                 }
> diff --git a/hw/net/vmxnet_tx_pkt.c b/hw/net/vmxnet_tx_pkt.c
> index f7344c4..eb88ddf 100644
> --- a/hw/net/vmxnet_tx_pkt.c
> +++ b/hw/net/vmxnet_tx_pkt.c
> @@ -142,11 +142,24 @@ static bool vmxnet_tx_pkt_parse_headers(struct VmxnetTxPkt *pkt)
> 
>     bytes_read = iov_to_buf(pkt->raw, pkt->raw_frags, 0, l2_hdr->iov_base,
>                             ETH_MAX_L2_HDR_LEN);
> -    if (bytes_read < ETH_MAX_L2_HDR_LEN) {
> +    if (bytes_read < sizeof(struct eth_header)) {
> +        l2_hdr->iov_len = 0;
> +        return false;
> +    }
> +
> +    l2_hdr->iov_len = sizeof(struct eth_header);
> +    switch (be16_to_cpu(PKT_GET_ETH_HDR(l2_hdr->iov_base)->h_proto)) {
> +    case ETH_P_VLAN:
> +        l2_hdr->iov_len += sizeof(struct vlan_header);
> +        break;
> +    case ETH_P_DVLAN:
> +        l2_hdr->iov_len += 2 * sizeof(struct vlan_header);
> +        break;
> +    }
> +
> +    if (bytes_read < l2_hdr->iov_len) {
>         l2_hdr->iov_len = 0;
>         return false;
> -    } else {
> -        l2_hdr->iov_len = eth_get_l2_hdr_length(l2_hdr->iov_base);
>     }
> 
>     l3_proto = eth_get_l3_proto(l2_hdr->iov_base, l2_hdr->iov_len);
> -- 
> 1.9.1
> 

Re: [Qemu-devel] [PATCH] net/vmxnet3: Refine l2 header validation

[Stefan Hajnoczi]

On Tue, Aug 18, 2015 at 12:45:55PM +0300, Shmulik Ladkani wrote:
> From: Dana Rubin <dana.rubin@ravellosystems.com>
> 
> Validation of l2 header length assumed minimal packet size as
> eth_header + 2 * vlan_header regardless of the actual protocol.
> 
> This caused crash for valid non-IP packets shorter than 22 bytes, as
> 'tx_pkt->packet_type' hasn't been assigned for such packets, and
> 'vmxnet3_on_tx_done_update_stats()' expects it to be properly set.
> 
> Refine header length validation in 'vmxnet_tx_pkt_parse_headers'.
> Check its return value during packet processing flow.
> 
> As a side effect, in case IPv4 and IPv6 header validation failure,
> corrupt packets will be dropped.
> 
> Signed-off-by: Dana Rubin <dana.rubin@ravellosystems.com>
> Signed-off-by: Shmulik Ladkani <shmulik.ladkani@ravellosystems.com>
> ---
>  hw/net/vmxnet3.c       |  4 +---
>  hw/net/vmxnet_tx_pkt.c | 19 ++++++++++++++++---
>  2 files changed, 17 insertions(+), 6 deletions(-)

Thanks, applied to my net tree:
https://github.com/stefanha/qemu/commits/net

Stefan

Re: [Qemu-devel] [PATCH] net/vmxnet3: Refine l2 header validation

[Shmulik Ladkani]

Hi,

On Thu, 3 Sep 2015 17:45:34 +0100 Stefan Hajnoczi <stefanha@gmail.com> wrote:
> Thanks, applied to my net tree:
> https://github.com/stefanha/qemu/commits/net

For some reason, the patch isn't present on Stefan's last pull requests.

Can you please verify this gets merged?

Thanks,
Shmulik

Re: [Qemu-devel] [PATCH] net/vmxnet3: Refine l2 header validation

[Jason Wang]

On 09/18/2015 02:13 PM, Shmulik Ladkani wrote:
> Hi,
>
> On Thu, 3 Sep 2015 17:45:34 +0100 Stefan Hajnoczi <stefanha@gmail.com> wrote:
>> Thanks, applied to my net tree:
>> https://github.com/stefanha/qemu/commits/net
> For some reason, the patch isn't present on Stefan's last pull requests.
>
> Can you please verify this gets merged?
>
> Thanks,
> Shmulik

Applied in https://github.com/jasowang/qemu/commits/net

Will be in next pull request.

Thanks.