diff mbox series

[net-next,1/2] seg6: add NEXT-C-SID support for SRv6 End.X behavior

Message ID 20230731175117.17376-2-andrea.mayer@uniroma2.it
State New
Headers
Series seg6: add NEXT-C-SID support for SRv6 End.X behavior |

Commit Message

Andrea Mayer July 31, 2023, 5:51 p.m. UTC 
  The NEXT-C-SID mechanism described in [1] offers the possibility of
encoding several SRv6 segments within a single 128 bit SID address. Such
a SID address is called a Compressed SID (C-SID) container. In this way,
the length of the SID List can be drastically reduced.

A SID instantiated with the NEXT-C-SID flavor considers an IPv6 address
logically structured in three main blocks: i) Locator-Block; ii)
Locator-Node Function; iii) Argument.

                        C-SID container
+------------------------------------------------------------------+
|     Locator-Block      |Loc-Node|            Argument            |
|                        |Function|                                |
+------------------------------------------------------------------+
<--------- B -----------> <- NF -> <------------- A --------------->

   (i) The Locator-Block can be any IPv6 prefix available to the provider;

  (ii) The Locator-Node Function represents the node and the function to
       be triggered when a packet is received on the node;

 (iii) The Argument carries the remaining C-SIDs in the current C-SID
       container.

This patch leverages the NEXT-C-SID mechanism previously introduced in the
Linux SRv6 subsystem [2] to support SID compression capabilities in the
SRv6 End.X behavior [3].
An SRv6 End.X behavior with NEXT-C-SID flavor works as an End.X behavior
but it is capable of processing the compressed SID List encoded in C-SID
containers.

An SRv6 End.X behavior with NEXT-C-SID flavor can be configured to support
user-provided Locator-Block and Locator-Node Function lengths. In this
implementation, such lengths must be evenly divisible by 8 (i.e. must be
byte-aligned), otherwise the kernel informs the user about invalid
values with a meaningful error code and message through netlink_ext_ack.

If Locator-Block and/or Locator-Node Function lengths are not provided
by the user during configuration of an SRv6 End.X behavior instance with
NEXT-C-SID flavor, the kernel will choose their default values i.e.,
32-bit Locator-Block and 16-bit Locator-Node Function.

[1] - https://datatracker.ietf.org/doc/html/draft-ietf-spring-srv6-srh-compression
[2] - https://lore.kernel.org/all/20220912171619.16943-1-andrea.mayer@uniroma2.it/
[3] - https://datatracker.ietf.org/doc/html/rfc8986#name-endx-l3-cross-connect

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
---
 net/ipv6/seg6_local.c | 108 ++++++++++++++++++++++++++++++++++--------
 1 file changed, 88 insertions(+), 20 deletions(-)

Comments

Hangbin Liu Aug. 3, 2023, 9:30 a.m. UTC | #1 
On Mon, Jul 31, 2023 at 07:51:16PM +0200, Andrea Mayer wrote:
> +/* Processing of SRv6 End, End.X, and End.T behaviors can be extended through
> + * the flavors framework. These behaviors must report the subset of (flavor)
> + * operations they currently implement. In this way, if a user specifies a
> + * flavor combination that is not supported by a given End* behavior, the
> + * kernel refuses to instantiate the tunnel reporting the error.
> + */
> +static int seg6_flv_supp_ops_by_action(int action, __u32 *fops)
> +{
> +	switch (action) {
> +	case SEG6_LOCAL_ACTION_END:
> +		*fops = SEG6_LOCAL_END_FLV_SUPP_OPS;
> +		break;
> +	case SEG6_LOCAL_ACTION_END_X:
> +		*fops = SEG6_LOCAL_END_X_FLV_SUPP_OPS;
> +		break;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	return 0;
>  }
>  

...

> @@ -2070,7 +2131,8 @@ static int parse_nla_flavors(struct nlattr **attrs, struct seg6_local_lwt *slwt,
>  {
>  	struct seg6_flavors_info *finfo = &slwt->flv_info;
>  	struct nlattr *tb[SEG6_LOCAL_FLV_MAX + 1];
> -	unsigned long fops;
> +	int action = slwt->action;
> +	__u32 fops, supp_fops = 0;
>  	int rc;
>  
>  	rc = nla_parse_nested_deprecated(tb, SEG6_LOCAL_FLV_MAX,
> @@ -2086,7 +2148,8 @@ static int parse_nla_flavors(struct nlattr **attrs, struct seg6_local_lwt *slwt,
>  		return -EINVAL;
>  
>  	fops = nla_get_u32(tb[SEG6_LOCAL_FLV_OPERATION]);
> -	if (fops & ~SEG6_LOCAL_FLV_SUPP_OPS) {
> +	rc = seg6_flv_supp_ops_by_action(action, &supp_fops);
> +	if (rc < 0 || !supp_fops || (fops & ~supp_fops)) {

if rc == 0, the supp_fops won't be 0.

Thanks
Hangbin
Andrea Mayer Aug. 4, 2023, 12:41 p.m. UTC | #2 
Hi Hangbin,
thanks for your time. Please see below.

On Thu, 3 Aug 2023 17:30:28 +0800
Hangbin Liu <liuhangbin@gmail.com> wrote:

> On Mon, Jul 31, 2023 at 07:51:16PM +0200, Andrea Mayer wrote:
> > +/* Processing of SRv6 End, End.X, and End.T behaviors can be extended through
> > + * the flavors framework. These behaviors must report the subset of (flavor)
> > + * operations they currently implement. In this way, if a user specifies a
> > + * flavor combination that is not supported by a given End* behavior, the
> > + * kernel refuses to instantiate the tunnel reporting the error.
> > + */
> > +static int seg6_flv_supp_ops_by_action(int action, __u32 *fops)
> > +{
> > +	switch (action) {
> > +	case SEG6_LOCAL_ACTION_END:
> > +		*fops = SEG6_LOCAL_END_FLV_SUPP_OPS;
> > +		break;
> > +	case SEG6_LOCAL_ACTION_END_X:
> > +		*fops = SEG6_LOCAL_END_X_FLV_SUPP_OPS;
> > +		break;
> > +	default:
> > +		return -EOPNOTSUPP;
> > +	}
> > +
> > +	return 0;
> >  }
> >  
> 
> ...
> 
> > @@ -2070,7 +2131,8 @@ static int parse_nla_flavors(struct nlattr **attrs, struct seg6_local_lwt *slwt,
> >  {
> >  	struct seg6_flavors_info *finfo = &slwt->flv_info;
> >  	struct nlattr *tb[SEG6_LOCAL_FLV_MAX + 1];
> > -	unsigned long fops;
> > +	int action = slwt->action;
> > +	__u32 fops, supp_fops = 0;
> >  	int rc;
> >  
> >  	rc = nla_parse_nested_deprecated(tb, SEG6_LOCAL_FLV_MAX,
> > @@ -2086,7 +2148,8 @@ static int parse_nla_flavors(struct nlattr **attrs, struct seg6_local_lwt *slwt,
> >  		return -EINVAL;
> >  
> >  	fops = nla_get_u32(tb[SEG6_LOCAL_FLV_OPERATION]);
> > -	if (fops & ~SEG6_LOCAL_FLV_SUPP_OPS) {
> > +	rc = seg6_flv_supp_ops_by_action(action, &supp_fops);
> > +	if (rc < 0 || !supp_fops || (fops & ~supp_fops)) {
> 
> if rc == 0, the supp_fops won't be 0.
> 

Yes, you're right.

In this patch, supp_fops is always set properly when rc == 0.
Since seg6_flv_supp_ops_by_action() should be extended in the event that other
behaviors receive flavors support, I added this check in case the "supp_fops"
field was set incorrectly or not set at all.
Note that supp_fops == 0 must be considered an inadmissible value.


So, I think we have two possibilities:
  i) remove this "defensive" check, assuming that supp_fops will always be set
     correctly by seg6_flv_supp_ops_by_action() (when rc == 0, like in this
     patch); 
 ii) improve the check by explicitly indicating with a pr_warn_once, for
     example, the condition that is occurring is unexpected.

for (ii), something like this:

parse_nla_flavors(...)
{
    [...]
    supp_fops = 0;
    [...]

    rc = seg6_flv_supp_ops_by_action(action, &supp_fops);
    if (!rc && !supp_fops) {
   	 /* supported flavors mask cannot be zero as it is considered to
   	  * be invalid.
   	  */
   	 pr_warn_once("seg6local: invalid Flavor operation(s)");
   	 return -EINVAL;
    }

    fops = nla_get_u32(tb[SEG6_LOCAL_FLV_OPERATION]);
    if (rc < 0 || (fops & ~supp_fops)) {
   	 NL_SET_ERR_MSG(extack, "Unsupported Flavor operation(s)");
   	 return -EOPNOTSUPP;
    }

    finfo->flv_ops = fops;

    [...]
}

parse_nla_flavors() is called in the control path so another check would not
hit performance. I am more inclined to consider solution (ii).

What do you think?

> Thanks
> Hangbin

Ciao,
Andrea
Hangbin Liu Aug. 5, 2023, 8:17 a.m. UTC | #3 
On Fri, Aug 04, 2023 at 02:41:18PM +0200, Andrea Mayer wrote:
> Hi Hangbin,
> thanks for your time. Please see below.
> 
> On Thu, 3 Aug 2023 17:30:28 +0800
> Hangbin Liu <liuhangbin@gmail.com> wrote:
> 
> > On Mon, Jul 31, 2023 at 07:51:16PM +0200, Andrea Mayer wrote:
> > > +/* Processing of SRv6 End, End.X, and End.T behaviors can be extended through
> > > + * the flavors framework. These behaviors must report the subset of (flavor)
> > > + * operations they currently implement. In this way, if a user specifies a
> > > + * flavor combination that is not supported by a given End* behavior, the
> > > + * kernel refuses to instantiate the tunnel reporting the error.
> > > + */
> > > +static int seg6_flv_supp_ops_by_action(int action, __u32 *fops)
> > > +{
> > > +	switch (action) {
> > > +	case SEG6_LOCAL_ACTION_END:
> > > +		*fops = SEG6_LOCAL_END_FLV_SUPP_OPS;
> > > +		break;
> > > +	case SEG6_LOCAL_ACTION_END_X:
> > > +		*fops = SEG6_LOCAL_END_X_FLV_SUPP_OPS;
> > > +		break;
> > > +	default:
> > > +		return -EOPNOTSUPP;
> > > +	}
> > > +
> > > +	return 0;
> > >  }
> > >  
> > 
> > ...
> > 
> > > @@ -2070,7 +2131,8 @@ static int parse_nla_flavors(struct nlattr **attrs, struct seg6_local_lwt *slwt,
> > >  {
> > >  	struct seg6_flavors_info *finfo = &slwt->flv_info;
> > >  	struct nlattr *tb[SEG6_LOCAL_FLV_MAX + 1];
> > > -	unsigned long fops;
> > > +	int action = slwt->action;
> > > +	__u32 fops, supp_fops = 0;
> > >  	int rc;
> > >  
> > >  	rc = nla_parse_nested_deprecated(tb, SEG6_LOCAL_FLV_MAX,
> > > @@ -2086,7 +2148,8 @@ static int parse_nla_flavors(struct nlattr **attrs, struct seg6_local_lwt *slwt,
> > >  		return -EINVAL;
> > >  
> > >  	fops = nla_get_u32(tb[SEG6_LOCAL_FLV_OPERATION]);
> > > -	if (fops & ~SEG6_LOCAL_FLV_SUPP_OPS) {
> > > +	rc = seg6_flv_supp_ops_by_action(action, &supp_fops);
> > > +	if (rc < 0 || !supp_fops || (fops & ~supp_fops)) {
> > 
> > if rc == 0, the supp_fops won't be 0.
> > 
> 
> Yes, you're right.
> 
> In this patch, supp_fops is always set properly when rc == 0.
> Since seg6_flv_supp_ops_by_action() should be extended in the event that other
> behaviors receive flavors support, I added this check in case the "supp_fops"
> field was set incorrectly or not set at all.
> Note that supp_fops == 0 must be considered an inadmissible value.
> 
> 
> So, I think we have two possibilities:
>   i) remove this "defensive" check, assuming that supp_fops will always be set
>      correctly by seg6_flv_supp_ops_by_action() (when rc == 0, like in this
>      patch); 
>  ii) improve the check by explicitly indicating with a pr_warn_once, for
>      example, the condition that is occurring is unexpected.
> 
> for (ii), something like this:
> 
> parse_nla_flavors(...)
> {
>     [...]
>     supp_fops = 0;
>     [...]
> 
>     rc = seg6_flv_supp_ops_by_action(action, &supp_fops);
>     if (!rc && !supp_fops) {
>    	 /* supported flavors mask cannot be zero as it is considered to
>    	  * be invalid.
>    	  */
>    	 pr_warn_once("seg6local: invalid Flavor operation(s)");
>    	 return -EINVAL;
>     }

Do you mean there is a possibility *in future* that the supp_fops could be 0
with rc == 0? If yes, this check would make sense(although we can add this
check when it's true). If not. I don't see a need to have this check.

And some static analysis tool would report warn for this code.

Thanks
Hangbin
> 
>     fops = nla_get_u32(tb[SEG6_LOCAL_FLV_OPERATION]);
>     if (rc < 0 || (fops & ~supp_fops)) {
>    	 NL_SET_ERR_MSG(extack, "Unsupported Flavor operation(s)");
>    	 return -EOPNOTSUPP;
>     }
> 
>     finfo->flv_ops = fops;
> 
>     [...]
> }
> 
> parse_nla_flavors() is called in the control path so another check would not
> hit performance. I am more inclined to consider solution (ii).
> 
> What do you think?
> 
> > Thanks
> > Hangbin
> 
> Ciao,
> Andrea
Andrea Mayer Aug. 8, 2023, 1:52 p.m. UTC | #4 
On Sat, 5 Aug 2023 16:17:03 +0800
Hangbin Liu <liuhangbin@gmail.com> wrote:

> On Fri, Aug 04, 2023 at 02:41:18PM +0200, Andrea Mayer wrote:
> > Hi Hangbin,
> > thanks for your time. Please see below.
> > 
> > On Thu, 3 Aug 2023 17:30:28 +0800
> > Hangbin Liu <liuhangbin@gmail.com> wrote:
> > 
> > > On Mon, Jul 31, 2023 at 07:51:16PM +0200, Andrea Mayer wrote:
> > > > +/* Processing of SRv6 End, End.X, and End.T behaviors can be extended through
> > > > + * the flavors framework. These behaviors must report the subset of (flavor)
> > > > + * operations they currently implement. In this way, if a user specifies a
> > > > + * flavor combination that is not supported by a given End* behavior, the
> > > > + * kernel refuses to instantiate the tunnel reporting the error.
> > > > + */
> > > > +static int seg6_flv_supp_ops_by_action(int action, __u32 *fops)
> > > > +{
> > > > +	switch (action) {
> > > > +	case SEG6_LOCAL_ACTION_END:
> > > > +		*fops = SEG6_LOCAL_END_FLV_SUPP_OPS;
> > > > +		break;
> > > > +	case SEG6_LOCAL_ACTION_END_X:
> > > > +		*fops = SEG6_LOCAL_END_X_FLV_SUPP_OPS;
> > > > +		break;
> > > > +	default:
> > > > +		return -EOPNOTSUPP;
> > > > +	}
> > > > +
> > > > +	return 0;
> > > >  }
> > > >  
> > > 
> > > ...
> > > 
> > > > @@ -2070,7 +2131,8 @@ static int parse_nla_flavors(struct nlattr **attrs, struct seg6_local_lwt *slwt,
> > > >  {
> > > >  	struct seg6_flavors_info *finfo = &slwt->flv_info;
> > > >  	struct nlattr *tb[SEG6_LOCAL_FLV_MAX + 1];
> > > > -	unsigned long fops;
> > > > +	int action = slwt->action;
> > > > +	__u32 fops, supp_fops = 0;
> > > >  	int rc;
> > > >  
> > > >  	rc = nla_parse_nested_deprecated(tb, SEG6_LOCAL_FLV_MAX,
> > > > @@ -2086,7 +2148,8 @@ static int parse_nla_flavors(struct nlattr **attrs, struct seg6_local_lwt *slwt,
> > > >  		return -EINVAL;
> > > >  
> > > >  	fops = nla_get_u32(tb[SEG6_LOCAL_FLV_OPERATION]);
> > > > -	if (fops & ~SEG6_LOCAL_FLV_SUPP_OPS) {
> > > > +	rc = seg6_flv_supp_ops_by_action(action, &supp_fops);
> > > > +	if (rc < 0 || !supp_fops || (fops & ~supp_fops)) {
> > > 
> > > if rc == 0, the supp_fops won't be 0.
> > > 
> > 
> > Yes, you're right.
> > 
> > In this patch, supp_fops is always set properly when rc == 0.
> > Since seg6_flv_supp_ops_by_action() should be extended in the event that other
> > behaviors receive flavors support, I added this check in case the "supp_fops"
> > field was set incorrectly or not set at all.
> > Note that supp_fops == 0 must be considered an inadmissible value.
> > 
> > 
> > So, I think we have two possibilities:
> >   i) remove this "defensive" check, assuming that supp_fops will always be set
> >      correctly by seg6_flv_supp_ops_by_action() (when rc == 0, like in this
> >      patch); 
> >  ii) improve the check by explicitly indicating with a pr_warn_once, for
> >      example, the condition that is occurring is unexpected.
> > 
> > for (ii), something like this:
> > 
> > parse_nla_flavors(...)
> > {
> >     [...]
> >     supp_fops = 0;
> >     [...]
> > 
> >     rc = seg6_flv_supp_ops_by_action(action, &supp_fops);
> >     if (!rc && !supp_fops) {
> >    	 /* supported flavors mask cannot be zero as it is considered to
> >    	  * be invalid.
> >    	  */
> >    	 pr_warn_once("seg6local: invalid Flavor operation(s)");
> >    	 return -EINVAL;
> >     }
> 
> Do you mean there is a possibility *in future* that the supp_fops could be 0
> with rc == 0? If yes, this check would make sense(although we can add this
> check when it's true). If not. I don't see a need to have this check.
> 
> And some static analysis tool would report warn for this code.
> 

Good points, thanks.
There is no possibility at the moment that supp_fops could be 0 with rc == 0.
That check is going to be removed in v2.

> Thanks
> Hangbin

Ciao,
Andrea

> > 
> >     fops = nla_get_u32(tb[SEG6_LOCAL_FLV_OPERATION]);
> >     if (rc < 0 || (fops & ~supp_fops)) {
> >    	 NL_SET_ERR_MSG(extack, "Unsupported Flavor operation(s)");
> >    	 return -EOPNOTSUPP;
> >     }
> > 
> >     finfo->flv_ops = fops;
> > 
> >     [...]
> > }
> > 
> > parse_nla_flavors() is called in the control path so another check would not
> > hit performance. I am more inclined to consider solution (ii).
> > 
> > What do you think?
> > 
> > > Thanks
> > > Hangbin
> > 
> > Ciao,
> > Andrea
diff mbox series

Patch

diff --git a/net/ipv6/seg6_local.c b/net/ipv6/seg6_local.c
index dd433cc265c8..ea7261872fae 100644
--- a/net/ipv6/seg6_local.c
+++ b/net/ipv6/seg6_local.c
@@ -109,15 +109,19 @@  struct bpf_lwt_prog {
 #define next_csid_chk_lcnode_fn_bits(flen)		\
 	next_csid_chk_lcblock_bits(flen)
 
+/* flag indicating that flavors are set up for a given End* behavior */
+#define SEG6_F_LOCAL_FLAVORS		SEG6_F_ATTR(SEG6_LOCAL_FLAVORS)
+
 #define SEG6_F_LOCAL_FLV_OP(flvname)	BIT(SEG6_LOCAL_FLV_OP_##flvname)
+#define SEG6_F_LOCAL_FLV_NEXT_CSID	SEG6_F_LOCAL_FLV_OP(NEXT_CSID)
 #define SEG6_F_LOCAL_FLV_PSP		SEG6_F_LOCAL_FLV_OP(PSP)
 
 /* Supported RFC8986 Flavor operations are reported in this bitmask */
 #define SEG6_LOCAL_FLV8986_SUPP_OPS	SEG6_F_LOCAL_FLV_PSP
 
-/* Supported Flavor operations are reported in this bitmask */
-#define SEG6_LOCAL_FLV_SUPP_OPS		(SEG6_F_LOCAL_FLV_OP(NEXT_CSID) | \
+#define SEG6_LOCAL_END_FLV_SUPP_OPS	(SEG6_F_LOCAL_FLV_NEXT_CSID | \
 					 SEG6_LOCAL_FLV8986_SUPP_OPS)
+#define SEG6_LOCAL_END_X_FLV_SUPP_OPS	SEG6_F_LOCAL_FLV_NEXT_CSID
 
 struct seg6_flavors_info {
 	/* Flavor operations */
@@ -411,9 +415,72 @@  static int end_next_csid_core(struct sk_buff *skb, struct seg6_local_lwt *slwt)
 	return input_action_end_finish(skb, slwt);
 }
 
+static int input_action_end_x_finish(struct sk_buff *skb,
+				     struct seg6_local_lwt *slwt)
+{
+	seg6_lookup_nexthop(skb, &slwt->nh6, 0);
+
+	return dst_input(skb);
+}
+
+static int input_action_end_x_core(struct sk_buff *skb,
+				   struct seg6_local_lwt *slwt)
+{
+	struct ipv6_sr_hdr *srh;
+
+	srh = get_and_validate_srh(skb);
+	if (!srh)
+		goto drop;
+
+	advance_nextseg(srh, &ipv6_hdr(skb)->daddr);
+
+	return input_action_end_x_finish(skb, slwt);
+
+drop:
+	kfree_skb(skb);
+	return -EINVAL;
+}
+
+static int end_x_next_csid_core(struct sk_buff *skb,
+				struct seg6_local_lwt *slwt)
+{
+	const struct seg6_flavors_info *finfo = &slwt->flv_info;
+	struct in6_addr *daddr = &ipv6_hdr(skb)->daddr;
+
+	if (seg6_next_csid_is_arg_zero(daddr, finfo))
+		return input_action_end_x_core(skb, slwt);
+
+	/* update DA */
+	seg6_next_csid_advance_arg(daddr, finfo);
+
+	return input_action_end_x_finish(skb, slwt);
+}
+
 static bool seg6_next_csid_enabled(__u32 fops)
 {
-	return fops & BIT(SEG6_LOCAL_FLV_OP_NEXT_CSID);
+	return fops & SEG6_F_LOCAL_FLV_NEXT_CSID;
+}
+
+/* Processing of SRv6 End, End.X, and End.T behaviors can be extended through
+ * the flavors framework. These behaviors must report the subset of (flavor)
+ * operations they currently implement. In this way, if a user specifies a
+ * flavor combination that is not supported by a given End* behavior, the
+ * kernel refuses to instantiate the tunnel reporting the error.
+ */
+static int seg6_flv_supp_ops_by_action(int action, __u32 *fops)
+{
+	switch (action) {
+	case SEG6_LOCAL_ACTION_END:
+		*fops = SEG6_LOCAL_END_FLV_SUPP_OPS;
+		break;
+	case SEG6_LOCAL_ACTION_END_X:
+		*fops = SEG6_LOCAL_END_X_FLV_SUPP_OPS;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
 }
 
 /* We describe the packet state in relation to the absence/presence of the SRH
@@ -746,21 +813,14 @@  static int input_action_end(struct sk_buff *skb, struct seg6_local_lwt *slwt)
 /* regular endpoint, and forward to specified nexthop */
 static int input_action_end_x(struct sk_buff *skb, struct seg6_local_lwt *slwt)
 {
-	struct ipv6_sr_hdr *srh;
-
-	srh = get_and_validate_srh(skb);
-	if (!srh)
-		goto drop;
-
-	advance_nextseg(srh, &ipv6_hdr(skb)->daddr);
-
-	seg6_lookup_nexthop(skb, &slwt->nh6, 0);
+	const struct seg6_flavors_info *finfo = &slwt->flv_info;
+	__u32 fops = finfo->flv_ops;
 
-	return dst_input(skb);
+	/* check for the presence of NEXT-C-SID since it applies first */
+	if (seg6_next_csid_enabled(fops))
+		return end_x_next_csid_core(skb, slwt);
 
-drop:
-	kfree_skb(skb);
-	return -EINVAL;
+	return input_action_end_x_core(skb, slwt);
 }
 
 static int input_action_end_t(struct sk_buff *skb, struct seg6_local_lwt *slwt)
@@ -1404,13 +1464,14 @@  static struct seg6_action_desc seg6_action_table[] = {
 		.action		= SEG6_LOCAL_ACTION_END,
 		.attrs		= 0,
 		.optattrs	= SEG6_F_LOCAL_COUNTERS |
-				  SEG6_F_ATTR(SEG6_LOCAL_FLAVORS),
+				  SEG6_F_LOCAL_FLAVORS,
 		.input		= input_action_end,
 	},
 	{
 		.action		= SEG6_LOCAL_ACTION_END_X,
 		.attrs		= SEG6_F_ATTR(SEG6_LOCAL_NH6),
-		.optattrs	= SEG6_F_LOCAL_COUNTERS,
+		.optattrs	= SEG6_F_LOCAL_COUNTERS |
+				  SEG6_F_LOCAL_FLAVORS,
 		.input		= input_action_end_x,
 	},
 	{
@@ -2070,7 +2131,8 @@  static int parse_nla_flavors(struct nlattr **attrs, struct seg6_local_lwt *slwt,
 {
 	struct seg6_flavors_info *finfo = &slwt->flv_info;
 	struct nlattr *tb[SEG6_LOCAL_FLV_MAX + 1];
-	unsigned long fops;
+	int action = slwt->action;
+	__u32 fops, supp_fops = 0;
 	int rc;
 
 	rc = nla_parse_nested_deprecated(tb, SEG6_LOCAL_FLV_MAX,
@@ -2086,7 +2148,8 @@  static int parse_nla_flavors(struct nlattr **attrs, struct seg6_local_lwt *slwt,
 		return -EINVAL;
 
 	fops = nla_get_u32(tb[SEG6_LOCAL_FLV_OPERATION]);
-	if (fops & ~SEG6_LOCAL_FLV_SUPP_OPS) {
+	rc = seg6_flv_supp_ops_by_action(action, &supp_fops);
+	if (rc < 0 || !supp_fops || (fops & ~supp_fops)) {
 		NL_SET_ERR_MSG(extack, "Unsupported Flavor operation(s)");
 		return -EOPNOTSUPP;
 	}
@@ -2618,6 +2681,11 @@  int __init seg6_local_init(void)
 	 */
 	BUILD_BUG_ON(SEG6_LOCAL_MAX + 1 > BITS_PER_TYPE(unsigned long));
 
+	/* Check whether the number of defined flavors exceeds the maximum
+	 * allowed value.
+	 */
+	BUILD_BUG_ON(SEG6_LOCAL_FLV_OP_MAX + 1 > BITS_PER_TYPE(__u32));
+
 	/* If the default NEXT-C-SID Locator-Block/Node Function lengths (in
 	 * bits) have been changed with invalid values, kernel build stops
 	 * here.