net/tap: fix zeroed flow mask configurations

Message ID 1533205980-7874-1-git-send-email-matan@mellanox.com
State Superseded, archived
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Series
  • net/tap: fix zeroed flow mask configurations
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Context Check Description
ci/Intel-compilation success Compilation OK
ci/checkpatch success coding style OK

Commit Message

Matan Azrad Aug. 2, 2018, 10:33 a.m.
The rte_flow meaning of zero flow mask configuration is to match all
the range of the item value.
For example, the flow eth / ipv4 dst spec 1.2.3.4 dst mask 0.0.0.0
should much all the ipv4 traffic from the rte_flow API perspective.

From some kernel perspectives the above rule means to ignore all the
ipv4 traffic (e.g. Ubuntu 16.04, 4.15.10).

Due to the fact that the tap PMD should provide the rte_flow meaning,
it is necessary to ignore the spec in case the mask is zero when it
forwards such like flows to the kernel.
So, the above rule should be translated to eth / ipv4 to get the
correct meaning.

Ignore spec configurations when the mask is zero.

Fixes: de96fe68ae95 ("net/tap: add basic flow API patterns and actions")
Cc: stable@dpdk.org

Signed-off-by: Matan Azrad <matan@mellanox.com>
---
 drivers/net/tap/tap_flow.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

Comments

Wiles, Keith Aug. 2, 2018, 12:03 p.m. | #1
> On Aug 2, 2018, at 5:33 AM, Matan Azrad <matan@mellanox.com> wrote:
> 
> The rte_flow meaning of zero flow mask configuration is to match all
> the range of the item value.
> For example, the flow eth / ipv4 dst spec 1.2.3.4 dst mask 0.0.0.0
> should much all the ipv4 traffic from the rte_flow API perspective.
> 
> From some kernel perspectives the above rule means to ignore all the
> ipv4 traffic (e.g. Ubuntu 16.04, 4.15.10).
> 
> Due to the fact that the tap PMD should provide the rte_flow meaning,
> it is necessary to ignore the spec in case the mask is zero when it
> forwards such like flows to the kernel.
> So, the above rule should be translated to eth / ipv4 to get the
> correct meaning.
> 
> Ignore spec configurations when the mask is zero.
> 
> Fixes: de96fe68ae95 ("net/tap: add basic flow API patterns and actions")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Matan Azrad <matan@mellanox.com>

Acked-by: Keith Wiles<keith.wiles@intel.com>

Regards,
Keith
Adrien Mazarguil Aug. 2, 2018, 2:27 p.m. | #2
On Thu, Aug 02, 2018 at 10:33:00AM +0000, Matan Azrad wrote:
> The rte_flow meaning of zero flow mask configuration is to match all
> the range of the item value.
> For example, the flow eth / ipv4 dst spec 1.2.3.4 dst mask 0.0.0.0
> should much all the ipv4 traffic from the rte_flow API perspective.
> 
> From some kernel perspectives the above rule means to ignore all the
> ipv4 traffic (e.g. Ubuntu 16.04, 4.15.10).
> 
> Due to the fact that the tap PMD should provide the rte_flow meaning,
> it is necessary to ignore the spec in case the mask is zero when it
> forwards such like flows to the kernel.
> So, the above rule should be translated to eth / ipv4 to get the
> correct meaning.
> 
> Ignore spec configurations when the mask is zero.

I would go further, one should be able to match IP address 0.0.0.0 for
instance. The PMD should only trust the mask on all fields without looking
at spec. See below for suggestions.

> Fixes: de96fe68ae95 ("net/tap: add basic flow API patterns and actions")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Matan Azrad <matan@mellanox.com>
> ---
>  drivers/net/tap/tap_flow.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/tap/tap_flow.c b/drivers/net/tap/tap_flow.c
> index 6b60e6d..993e6f6 100644
> --- a/drivers/net/tap/tap_flow.c
> +++ b/drivers/net/tap/tap_flow.c
> @@ -537,7 +537,8 @@ tap_flow_create_eth(const struct rte_flow_item *item, void *data)
>  	if (!flow)
>  		return 0;
>  	msg = &flow->msg;
> -	if (!is_zero_ether_addr(&spec->dst)) {
> +	if (!is_zero_ether_addr(&spec->dst) &&

This check should be removed.

> +	    !is_zero_ether_addr(&mask->dst)) {
>  		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_ETH_DST, ETHER_ADDR_LEN,
>  			   &spec->dst.addr_bytes);
>  		tap_nlattr_add(&msg->nh,
> @@ -651,13 +652,13 @@ tap_flow_create_ipv4(const struct rte_flow_item *item, void *data)
>  		info->eth_type = htons(ETH_P_IP);
>  	if (!spec)
>  		return 0;
> -	if (spec->hdr.dst_addr) {
> +	if (spec->hdr.dst_addr && mask->hdr.dst_addr) {

Ditto (before &&).

>  		tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_DST,
>  			     spec->hdr.dst_addr);
>  		tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_DST_MASK,
>  			     mask->hdr.dst_addr);
>  	}
> -	if (spec->hdr.src_addr) {
> +	if (spec->hdr.src_addr && mask->hdr.src_addr) {

Ditto.

>  		tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_SRC,
>  			     spec->hdr.src_addr);
>  		tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_SRC_MASK,
> @@ -707,13 +708,15 @@ tap_flow_create_ipv6(const struct rte_flow_item *item, void *data)
>  		info->eth_type = htons(ETH_P_IPV6);
>  	if (!spec)
>  		return 0;
> -	if (memcmp(spec->hdr.dst_addr, empty_addr, 16)) {
> +	if (memcmp(spec->hdr.dst_addr, empty_addr, 16) &&

Ditto.

> +	    memcmp(mask->hdr.dst_addr, empty_addr, 16)) {
>  		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_DST,
>  			   sizeof(spec->hdr.dst_addr), &spec->hdr.dst_addr);
>  		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_DST_MASK,
>  			   sizeof(mask->hdr.dst_addr), &mask->hdr.dst_addr);
>  	}
> -	if (memcmp(spec->hdr.src_addr, empty_addr, 16)) {
> +	if (memcmp(spec->hdr.src_addr, empty_addr, 16) &&

Ditto.

> +	    memcmp(mask->hdr.src_addr, empty_addr, 16)) {
>  		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_SRC,
>  			   sizeof(spec->hdr.src_addr), &spec->hdr.src_addr);
>  		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_SRC_MASK,
> -- 
> 2.7.4
>
Matan Azrad Aug. 2, 2018, 5:52 p.m. | #3
Hi Adrien

From: Adrien Mazarguil
> On Thu, Aug 02, 2018 at 10:33:00AM +0000, Matan Azrad wrote:
> > The rte_flow meaning of zero flow mask configuration is to match all
> > the range of the item value.
> > For example, the flow eth / ipv4 dst spec 1.2.3.4 dst mask 0.0.0.0
> > should much all the ipv4 traffic from the rte_flow API perspective.
> >
> > From some kernel perspectives the above rule means to ignore all the
> > ipv4 traffic (e.g. Ubuntu 16.04, 4.15.10).
> >
> > Due to the fact that the tap PMD should provide the rte_flow meaning,
> > it is necessary to ignore the spec in case the mask is zero when it
> > forwards such like flows to the kernel.
> > So, the above rule should be translated to eth / ipv4 to get the
> > correct meaning.
> >
> > Ignore spec configurations when the mask is zero.
> 
> I would go further, one should be able to match IP address 0.0.0.0 for instance.
> The PMD should only trust the mask on all fields without looking at spec.

The PMD should convert the RTE flow API to the device configuration,
So I can think on scenarios that the PMD should look on spec.

 See
> below for suggestions.
> 
> > Fixes: de96fe68ae95 ("net/tap: add basic flow API patterns and
> > actions")
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Matan Azrad <matan@mellanox.com>
> > ---
> >  drivers/net/tap/tap_flow.c | 13 ++++++++-----
> >  1 file changed, 8 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/net/tap/tap_flow.c b/drivers/net/tap/tap_flow.c
> > index 6b60e6d..993e6f6 100644
> > --- a/drivers/net/tap/tap_flow.c
> > +++ b/drivers/net/tap/tap_flow.c
> > @@ -537,7 +537,8 @@ tap_flow_create_eth(const struct rte_flow_item
> *item, void *data)
> >  	if (!flow)
> >  		return 0;
> >  	msg = &flow->msg;
> > -	if (!is_zero_ether_addr(&spec->dst)) {
> > +	if (!is_zero_ether_addr(&spec->dst) &&
> 
> This check should be removed.

I don't know why we need this check, and the below checks
So it should be tested before the change.
It may be a different issue.

> 
> > +	    !is_zero_ether_addr(&mask->dst)) {
> >  		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_ETH_DST,
> ETHER_ADDR_LEN,
> >  			   &spec->dst.addr_bytes);
> >  		tap_nlattr_add(&msg->nh,
> > @@ -651,13 +652,13 @@ tap_flow_create_ipv4(const struct rte_flow_item
> *item, void *data)
> >  		info->eth_type = htons(ETH_P_IP);
> >  	if (!spec)
> >  		return 0;
> > -	if (spec->hdr.dst_addr) {
> > +	if (spec->hdr.dst_addr && mask->hdr.dst_addr) {
> 
> Ditto (before &&).
> 
> >  		tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_DST,
> >  			     spec->hdr.dst_addr);
> >  		tap_nlattr_add32(&msg->nh,
> TCA_FLOWER_KEY_IPV4_DST_MASK,
> >  			     mask->hdr.dst_addr);
> >  	}
> > -	if (spec->hdr.src_addr) {
> > +	if (spec->hdr.src_addr && mask->hdr.src_addr) {
> 
> Ditto.
> 
> >  		tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_SRC,
> >  			     spec->hdr.src_addr);
> >  		tap_nlattr_add32(&msg->nh,
> TCA_FLOWER_KEY_IPV4_SRC_MASK, @@ -707,13
> > +708,15 @@ tap_flow_create_ipv6(const struct rte_flow_item *item, void
> *data)
> >  		info->eth_type = htons(ETH_P_IPV6);
> >  	if (!spec)
> >  		return 0;
> > -	if (memcmp(spec->hdr.dst_addr, empty_addr, 16)) {
> > +	if (memcmp(spec->hdr.dst_addr, empty_addr, 16) &&
> 
> Ditto.
> 
> > +	    memcmp(mask->hdr.dst_addr, empty_addr, 16)) {
> >  		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_DST,
> >  			   sizeof(spec->hdr.dst_addr), &spec->hdr.dst_addr);
> >  		tap_nlattr_add(&msg->nh,
> TCA_FLOWER_KEY_IPV6_DST_MASK,
> >  			   sizeof(mask->hdr.dst_addr), &mask->hdr.dst_addr);
> >  	}
> > -	if (memcmp(spec->hdr.src_addr, empty_addr, 16)) {
> > +	if (memcmp(spec->hdr.src_addr, empty_addr, 16) &&
> 
> Ditto.
> 
> > +	    memcmp(mask->hdr.src_addr, empty_addr, 16)) {
> >  		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_SRC,
> >  			   sizeof(spec->hdr.src_addr), &spec->hdr.src_addr);
> >  		tap_nlattr_add(&msg->nh,
> TCA_FLOWER_KEY_IPV6_SRC_MASK,
> > --
> > 2.7.4
> >
> 
> --
> Adrien Mazarguil
> 6WIND
Adrien Mazarguil Aug. 3, 2018, 8:20 a.m. | #4
Hi Matan,

On Thu, Aug 02, 2018 at 05:52:18PM +0000, Matan Azrad wrote:
> Hi Adrien
> 
> From: Adrien Mazarguil
> > On Thu, Aug 02, 2018 at 10:33:00AM +0000, Matan Azrad wrote:
> > > The rte_flow meaning of zero flow mask configuration is to match all
> > > the range of the item value.
> > > For example, the flow eth / ipv4 dst spec 1.2.3.4 dst mask 0.0.0.0
> > > should much all the ipv4 traffic from the rte_flow API perspective.
> > >
> > > From some kernel perspectives the above rule means to ignore all the
> > > ipv4 traffic (e.g. Ubuntu 16.04, 4.15.10).
> > >
> > > Due to the fact that the tap PMD should provide the rte_flow meaning,
> > > it is necessary to ignore the spec in case the mask is zero when it
> > > forwards such like flows to the kernel.
> > > So, the above rule should be translated to eth / ipv4 to get the
> > > correct meaning.
> > >
> > > Ignore spec configurations when the mask is zero.
> > 
> > I would go further, one should be able to match IP address 0.0.0.0 for instance.
> > The PMD should only trust the mask on all fields without looking at spec.
> 
> The PMD should convert the RTE flow API to the device configuration,
> So I can think on scenarios that the PMD should look on spec.

Obviously the PMD needs to take spec into account. What I meant is that for
each field, spec must be taken into account according to mask only.

For any given field, when mask is empty, don't look at spec, it's like a
wildcard. When mask is full, take spec as is, even if spec only contains
zeroed bits.

User intent in that case is to match a zero value exactly, so it must not
result in a wildcard match. If supported, when mask is partial, masked bits
are also matched exactly, even if these turn out to be a zero
value. Unmasked bits are considered wildcards.

In short, to address both the issue mentioned in the commit log and the one
I'm talking about, you only need to replace "spec" with "mask" in the
original code. More below.

>  See
> > below for suggestions.
> > 
> > > Fixes: de96fe68ae95 ("net/tap: add basic flow API patterns and
> > > actions")
> > > Cc: stable@dpdk.org
> > >
> > > Signed-off-by: Matan Azrad <matan@mellanox.com>
> > > ---
> > >  drivers/net/tap/tap_flow.c | 13 ++++++++-----
> > >  1 file changed, 8 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/drivers/net/tap/tap_flow.c b/drivers/net/tap/tap_flow.c
> > > index 6b60e6d..993e6f6 100644
> > > --- a/drivers/net/tap/tap_flow.c
> > > +++ b/drivers/net/tap/tap_flow.c
> > > @@ -537,7 +537,8 @@ tap_flow_create_eth(const struct rte_flow_item
> > *item, void *data)
> > >  	if (!flow)
> > >  		return 0;
> > >  	msg = &flow->msg;
> > > -	if (!is_zero_ether_addr(&spec->dst)) {
> > > +	if (!is_zero_ether_addr(&spec->dst) &&
> > 
> > This check should be removed.
> 
> I don't know why we need this check, and the below checks
> So it should be tested before the change.
> It may be a different issue.
> 
> > 
> > > +	    !is_zero_ether_addr(&mask->dst)) {

Should read:

 if (!is_zero_ether_addr(&mask->dst)) {

> > >  		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_ETH_DST,
> > ETHER_ADDR_LEN,
> > >  			   &spec->dst.addr_bytes);
> > >  		tap_nlattr_add(&msg->nh,
> > > @@ -651,13 +652,13 @@ tap_flow_create_ipv4(const struct rte_flow_item
> > *item, void *data)
> > >  		info->eth_type = htons(ETH_P_IP);
> > >  	if (!spec)
> > >  		return 0;
> > > -	if (spec->hdr.dst_addr) {
> > > +	if (spec->hdr.dst_addr && mask->hdr.dst_addr) {
> > 
> > Ditto (before &&).

Should read:

 if (mask->hdr.dst_addr) {

> > 
> > >  		tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_DST,
> > >  			     spec->hdr.dst_addr);
> > >  		tap_nlattr_add32(&msg->nh,
> > TCA_FLOWER_KEY_IPV4_DST_MASK,
> > >  			     mask->hdr.dst_addr);
> > >  	}
> > > -	if (spec->hdr.src_addr) {
> > > +	if (spec->hdr.src_addr && mask->hdr.src_addr) {
> > 
> > Ditto.

Should read:

 if (mask->hdr.dst_addr) {

> > >  		tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_SRC,
> > >  			     spec->hdr.src_addr);
> > >  		tap_nlattr_add32(&msg->nh,
> > TCA_FLOWER_KEY_IPV4_SRC_MASK, @@ -707,13
> > > +708,15 @@ tap_flow_create_ipv6(const struct rte_flow_item *item, void
> > *data)
> > >  		info->eth_type = htons(ETH_P_IPV6);
> > >  	if (!spec)
> > >  		return 0;
> > > -	if (memcmp(spec->hdr.dst_addr, empty_addr, 16)) {
> > > +	if (memcmp(spec->hdr.dst_addr, empty_addr, 16) &&
> > 
> > Ditto.

Should read:

 if (memcmp(mask->hdr.dst_addr, empty_addr, 16)) {

> > 
> > > +	    memcmp(mask->hdr.dst_addr, empty_addr, 16)) {
> > >  		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_DST,
> > >  			   sizeof(spec->hdr.dst_addr), &spec->hdr.dst_addr);
> > >  		tap_nlattr_add(&msg->nh,
> > TCA_FLOWER_KEY_IPV6_DST_MASK,
> > >  			   sizeof(mask->hdr.dst_addr), &mask->hdr.dst_addr);
> > >  	}
> > > -	if (memcmp(spec->hdr.src_addr, empty_addr, 16)) {
> > > +	if (memcmp(spec->hdr.src_addr, empty_addr, 16) &&
> > 
> > Ditto.

Should read:

 if (memcmp(mask->hdr.src_addr, empty_addr, 16)) {

> > 
> > > +	    memcmp(mask->hdr.src_addr, empty_addr, 16)) {
> > >  		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_SRC,
> > >  			   sizeof(spec->hdr.src_addr), &spec->hdr.src_addr);
> > >  		tap_nlattr_add(&msg->nh,
> > TCA_FLOWER_KEY_IPV6_SRC_MASK,
> > > --
> > > 2.7.4
> > >

The same issue exists with UDP and TCP ports by the way:

 -if (spec->hdr.dst_port & mask->hdr.dst_port)
 +if (mask->hdr.dst_port)

 -if (spec->hdr.src_port & mask->hdr.src_port)
 +if (mask->hdr.src_port)


 -if (spec->hdr.dst_port & mask->hdr.dst_port)
 +if (mask->hdr.dst_port)

 -if (spec->hdr.src_port & mask->hdr.src_port)
 +if (mask->hdr.src_port)

Otherwise one can't match traffic where source/destination ports are 0. Yes
such traffic should be invalid, however that's precisely why one would want
to match it: drop before it reaches the protocol stack.
Matan Azrad Aug. 5, 2018, 6:10 a.m. | #5
Hi Adrien

From: Adrien Mazarguil
> Hi Matan,
> 
> On Thu, Aug 02, 2018 at 05:52:18PM +0000, Matan Azrad wrote:
> > Hi Adrien
> >
> > From: Adrien Mazarguil
> > > On Thu, Aug 02, 2018 at 10:33:00AM +0000, Matan Azrad wrote:
> > > > The rte_flow meaning of zero flow mask configuration is to match
> > > > all the range of the item value.
> > > > For example, the flow eth / ipv4 dst spec 1.2.3.4 dst mask 0.0.0.0
> > > > should much all the ipv4 traffic from the rte_flow API perspective.
> > > >
> > > > From some kernel perspectives the above rule means to ignore all
> > > > the
> > > > ipv4 traffic (e.g. Ubuntu 16.04, 4.15.10).
> > > >
> > > > Due to the fact that the tap PMD should provide the rte_flow
> > > > meaning, it is necessary to ignore the spec in case the mask is
> > > > zero when it forwards such like flows to the kernel.
> > > > So, the above rule should be translated to eth / ipv4 to get the
> > > > correct meaning.
> > > >
> > > > Ignore spec configurations when the mask is zero.
> > >
> > > I would go further, one should be able to match IP address 0.0.0.0 for
> instance.
> > > The PMD should only trust the mask on all fields without looking at spec.
> >
> > The PMD should convert the RTE flow API to the device configuration,
> > So I can think on scenarios that the PMD should look on spec.
> 
> Obviously the PMD needs to take spec into account. What I meant is that for
> each field, spec must be taken into account according to mask only.
> 
> For any given field, when mask is empty, don't look at spec, it's like a wildcard.
> When mask is full, take spec as is, even if spec only contains zeroed bits.
> 
> User intent in that case is to match a zero value exactly, so it must not result in
> a wildcard match. If supported, when mask is partial, masked bits are also
> matched exactly, even if these turn out to be a zero value. Unmasked bits are
> considered wildcards.
> 

Yes I understand your point Adrien, but I mean that maybe sometimes some spec values should be converted to another spec values to get the correct translation of rte_flow for a special device.

Here, maybe IP_spec=0.0.0.0 is a special case that should be taken into account, so we must validate what's happen in Tap for this case to apply your suggestion too, Maybe there was some intentions for spec=0 cases from the current code author.
 

> In short, to address both the issue mentioned in the commit log and the one I'm
> talking about, you only need to replace "spec" with "mask" in the original code.
Adrien Mazarguil Aug. 6, 2018, 9:40 a.m. | #6
On Sun, Aug 05, 2018 at 06:10:55AM +0000, Matan Azrad wrote:
> Hi Adrien
> 
> From: Adrien Mazarguil
> > Hi Matan,
> > 
> > On Thu, Aug 02, 2018 at 05:52:18PM +0000, Matan Azrad wrote:
> > > Hi Adrien
> > >
> > > From: Adrien Mazarguil
> > > > On Thu, Aug 02, 2018 at 10:33:00AM +0000, Matan Azrad wrote:
> > > > > The rte_flow meaning of zero flow mask configuration is to match
> > > > > all the range of the item value.
> > > > > For example, the flow eth / ipv4 dst spec 1.2.3.4 dst mask 0.0.0.0
> > > > > should much all the ipv4 traffic from the rte_flow API perspective.
> > > > >
> > > > > From some kernel perspectives the above rule means to ignore all
> > > > > the
> > > > > ipv4 traffic (e.g. Ubuntu 16.04, 4.15.10).
> > > > >
> > > > > Due to the fact that the tap PMD should provide the rte_flow
> > > > > meaning, it is necessary to ignore the spec in case the mask is
> > > > > zero when it forwards such like flows to the kernel.
> > > > > So, the above rule should be translated to eth / ipv4 to get the
> > > > > correct meaning.
> > > > >
> > > > > Ignore spec configurations when the mask is zero.
> > > >
> > > > I would go further, one should be able to match IP address 0.0.0.0 for
> > instance.
> > > > The PMD should only trust the mask on all fields without looking at spec.
> > >
> > > The PMD should convert the RTE flow API to the device configuration,
> > > So I can think on scenarios that the PMD should look on spec.
> > 
> > Obviously the PMD needs to take spec into account. What I meant is that for
> > each field, spec must be taken into account according to mask only.
> > 
> > For any given field, when mask is empty, don't look at spec, it's like a wildcard.
> > When mask is full, take spec as is, even if spec only contains zeroed bits.
> > 
> > User intent in that case is to match a zero value exactly, so it must not result in
> > a wildcard match. If supported, when mask is partial, masked bits are also
> > matched exactly, even if these turn out to be a zero value. Unmasked bits are
> > considered wildcards.
> > 
> 
> Yes I understand your point Adrien, but I mean that maybe sometimes some spec values should be converted to another spec values to get the correct translation of rte_flow for a special device.
> 
> Here, maybe IP_spec=0.0.0.0 is a special case that should be taken into account, so we must validate what's happen in Tap for this case to apply your suggestion too, Maybe there was some intentions for spec=0 cases from the current code author.

I understand that's a lot of maybes :)

I've checked the code and I'am sure it's a mistake made by the original
author. See tap_flow_create_eth() for instance:

 if (!is_zero_ether_addr(&spec->dst)) {

Followed by:

 if (!is_zero_ether_addr(&mask->src))

This lack of consistency doesn't make any sense, it cannot be on purpose.

To my credentials I wrote a very similar code which uses TC flower in mlx5
and relies on mask (only) in order to retrieve spec. Have a look at
drivers/net/mlx5/mlx5_nl_flow.c. I validated that traffic where addresses
were all zeroes could be successfully matched.
Matan Azrad Aug. 6, 2018, 9:58 a.m. | #7
Hi Adrien

From: Adrien Mazarguil
> On Sun, Aug 05, 2018 at 06:10:55AM +0000, Matan Azrad wrote:
> > Hi Adrien
> >
> > From: Adrien Mazarguil
> > > Hi Matan,
> > >
> > > On Thu, Aug 02, 2018 at 05:52:18PM +0000, Matan Azrad wrote:
> > > > Hi Adrien
> > > >
> > > > From: Adrien Mazarguil
> > > > > On Thu, Aug 02, 2018 at 10:33:00AM +0000, Matan Azrad wrote:
> > > > > > The rte_flow meaning of zero flow mask configuration is to
> > > > > > match all the range of the item value.
> > > > > > For example, the flow eth / ipv4 dst spec 1.2.3.4 dst mask
> > > > > > 0.0.0.0 should much all the ipv4 traffic from the rte_flow API
> perspective.
> > > > > >
> > > > > > From some kernel perspectives the above rule means to ignore
> > > > > > all the
> > > > > > ipv4 traffic (e.g. Ubuntu 16.04, 4.15.10).
> > > > > >
> > > > > > Due to the fact that the tap PMD should provide the rte_flow
> > > > > > meaning, it is necessary to ignore the spec in case the mask
> > > > > > is zero when it forwards such like flows to the kernel.
> > > > > > So, the above rule should be translated to eth / ipv4 to get
> > > > > > the correct meaning.
> > > > > >
> > > > > > Ignore spec configurations when the mask is zero.
> > > > >
> > > > > I would go further, one should be able to match IP address
> > > > > 0.0.0.0 for
> > > instance.
> > > > > The PMD should only trust the mask on all fields without looking at
> spec.
> > > >
> > > > The PMD should convert the RTE flow API to the device
> > > > configuration, So I can think on scenarios that the PMD should look on
> spec.
> > >
> > > Obviously the PMD needs to take spec into account. What I meant is
> > > that for each field, spec must be taken into account according to mask
> only.
> > >
> > > For any given field, when mask is empty, don't look at spec, it's like a
> wildcard.
> > > When mask is full, take spec as is, even if spec only contains zeroed bits.
> > >
> > > User intent in that case is to match a zero value exactly, so it
> > > must not result in a wildcard match. If supported, when mask is
> > > partial, masked bits are also matched exactly, even if these turn
> > > out to be a zero value. Unmasked bits are considered wildcards.
> > >
> >
> > Yes I understand your point Adrien, but I mean that maybe sometimes
> some spec values should be converted to another spec values to get the
> correct translation of rte_flow for a special device.
> >
> > Here, maybe IP_spec=0.0.0.0 is a special case that should be taken into
> account, so we must validate what's happen in Tap for this case to apply your
> suggestion too, Maybe there was some intentions for spec=0 cases from the
> current code author.
> 
> I understand that's a lot of maybes :)
> 
> I've checked the code and I'am sure it's a mistake made by the original
> author. See tap_flow_create_eth() for instance:
> 
>  if (!is_zero_ether_addr(&spec->dst)) {
> 
> Followed by:
> 
>  if (!is_zero_ether_addr(&mask->src))
> 
> This lack of consistency doesn't make any sense, it cannot be on purpose.
> 
> To my credentials I wrote a very similar code which uses TC flower in mlx5
> and relies on mask (only) in order to retrieve spec. Have a look at
> drivers/net/mlx5/mlx5_nl_flow.c. I validated that traffic where addresses
> were all zeroes could be successfully matched.
>

I will check the spec zero cases and will update.

Thanks Adrien!

Patch

diff --git a/drivers/net/tap/tap_flow.c b/drivers/net/tap/tap_flow.c
index 6b60e6d..993e6f6 100644
--- a/drivers/net/tap/tap_flow.c
+++ b/drivers/net/tap/tap_flow.c
@@ -537,7 +537,8 @@  tap_flow_create_eth(const struct rte_flow_item *item, void *data)
 	if (!flow)
 		return 0;
 	msg = &flow->msg;
-	if (!is_zero_ether_addr(&spec->dst)) {
+	if (!is_zero_ether_addr(&spec->dst) &&
+	    !is_zero_ether_addr(&mask->dst)) {
 		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_ETH_DST, ETHER_ADDR_LEN,
 			   &spec->dst.addr_bytes);
 		tap_nlattr_add(&msg->nh,
@@ -651,13 +652,13 @@  tap_flow_create_ipv4(const struct rte_flow_item *item, void *data)
 		info->eth_type = htons(ETH_P_IP);
 	if (!spec)
 		return 0;
-	if (spec->hdr.dst_addr) {
+	if (spec->hdr.dst_addr && mask->hdr.dst_addr) {
 		tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_DST,
 			     spec->hdr.dst_addr);
 		tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_DST_MASK,
 			     mask->hdr.dst_addr);
 	}
-	if (spec->hdr.src_addr) {
+	if (spec->hdr.src_addr && mask->hdr.src_addr) {
 		tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_SRC,
 			     spec->hdr.src_addr);
 		tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_SRC_MASK,
@@ -707,13 +708,15 @@  tap_flow_create_ipv6(const struct rte_flow_item *item, void *data)
 		info->eth_type = htons(ETH_P_IPV6);
 	if (!spec)
 		return 0;
-	if (memcmp(spec->hdr.dst_addr, empty_addr, 16)) {
+	if (memcmp(spec->hdr.dst_addr, empty_addr, 16) &&
+	    memcmp(mask->hdr.dst_addr, empty_addr, 16)) {
 		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_DST,
 			   sizeof(spec->hdr.dst_addr), &spec->hdr.dst_addr);
 		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_DST_MASK,
 			   sizeof(mask->hdr.dst_addr), &mask->hdr.dst_addr);
 	}
-	if (memcmp(spec->hdr.src_addr, empty_addr, 16)) {
+	if (memcmp(spec->hdr.src_addr, empty_addr, 16) &&
+	    memcmp(mask->hdr.src_addr, empty_addr, 16)) {
 		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_SRC,
 			   sizeof(spec->hdr.src_addr), &spec->hdr.src_addr);
 		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_SRC_MASK,