Merge branch 'ioam-fixes'

Justin Iurman says:

====================
Correct the IOAM behavior for undefined trace type bits

(@Jakub @David: there will be a conflict for #2 when merging net->net-next, due
to commit [1]. The conflict is only 5-10 lines for #2 (#1 should be fine) inside
the file tools/testing/selftests/net/ioam6.sh, so quite short though possibly
ugly. Sorry for that, I didn't expect to post this one... Had I known, I'd have
made the opposite.)

Modify both the input and output behaviors regarding the trace type when one of
the undefined bits is set. The goal is to keep the interoperability when new
fields (aka new bits inside the range 12-21) will be defined.

The draft [2] says the following:
---------------------------------------------------------------
"Bit 12-21  Undefined.  These values are available for future
       assignment in the IOAM Trace-Type Registry (Section 8.2).
       Every future node data field corresponding to one of
       these bits MUST be 4-octets long.  An IOAM encapsulating
       node MUST set the value of each undefined bit to 0.  If
       an IOAM transit node receives a packet with one or more
       of these bits set to 1, it MUST either:

       1.  Add corresponding node data filled with the reserved
           value 0xFFFFFFFF, after the node data fields for the
           IOAM-Trace-Type bits defined above, such that the
           total node data added by this node in units of
           4-octets is equal to NodeLen, or

       2.  Not add any node data fields to the packet, even for
           the IOAM-Trace-Type bits defined above."
---------------------------------------------------------------

The output behavior has been modified to respect the fact that "an IOAM encap
node MUST set the value of each undefined bit to 0" (i.e., undefined bits can't
be set anymore).

As for the input behavior, current implementation is based on the second choice
(i.e., "not add any data fields to the packet [...]"). With this solution, any
interoperability is lost (i.e., if a new bit is defined, then an "old" kernel
implementation wouldn't fill IOAM data when such new bit is set inside the trace
type).

The input behavior is therefore relaxed and these undefined bits are now allowed
to be set. It is only possible thanks to the sentence "every future node data
field corresponding to one of these bits MUST be 4-octets long". Indeed, the
default empty value (the one for 4-octet fields) is inserted whenever an
undefined bit is set.

  [1] cfbe9b002109621bf9a282a4a24f9415ef14b57b
  [2] https://datatracker.ietf.org/doc/html/draft-ietf-ippm-ioam-data#section-5.4.1
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 67 insertions, 9 deletions

diff --git a/net/ipv6/ioam6.c b/net/ipv6/ioam6.c
index 5e8961004832..d128172bb549 100644
--- a/net/ipv6/ioam6.c
+++ b/net/ipv6/ioam6.c
@@ -770,6 +770,66 @@ static void __ioam6_fill_trace_data(struct sk_buff *skb,
 		data += sizeof(__be32);
 	}
 
+	/* bit12 undefined: filled with empty value */
+	if (trace->type.bit12) {
+		*(__be32 *)data = cpu_to_be32(IOAM6_U32_UNAVAILABLE);
+		data += sizeof(__be32);
+	}
+
+	/* bit13 undefined: filled with empty value */
+	if (trace->type.bit13) {
+		*(__be32 *)data = cpu_to_be32(IOAM6_U32_UNAVAILABLE);
+		data += sizeof(__be32);
+	}
+
+	/* bit14 undefined: filled with empty value */
+	if (trace->type.bit14) {
+		*(__be32 *)data = cpu_to_be32(IOAM6_U32_UNAVAILABLE);
+		data += sizeof(__be32);
+	}
+
+	/* bit15 undefined: filled with empty value */
+	if (trace->type.bit15) {
+		*(__be32 *)data = cpu_to_be32(IOAM6_U32_UNAVAILABLE);
+		data += sizeof(__be32);
+	}
+
+	/* bit16 undefined: filled with empty value */
+	if (trace->type.bit16) {
+		*(__be32 *)data = cpu_to_be32(IOAM6_U32_UNAVAILABLE);
+		data += sizeof(__be32);
+	}
+
+	/* bit17 undefined: filled with empty value */
+	if (trace->type.bit17) {
+		*(__be32 *)data = cpu_to_be32(IOAM6_U32_UNAVAILABLE);
+		data += sizeof(__be32);
+	}
+
+	/* bit18 undefined: filled with empty value */
+	if (trace->type.bit18) {
+		*(__be32 *)data = cpu_to_be32(IOAM6_U32_UNAVAILABLE);
+		data += sizeof(__be32);
+	}
+
+	/* bit19 undefined: filled with empty value */
+	if (trace->type.bit19) {
+		*(__be32 *)data = cpu_to_be32(IOAM6_U32_UNAVAILABLE);
+		data += sizeof(__be32);
+	}
+
+	/* bit20 undefined: filled with empty value */
+	if (trace->type.bit20) {
+		*(__be32 *)data = cpu_to_be32(IOAM6_U32_UNAVAILABLE);
+		data += sizeof(__be32);
+	}
+
+	/* bit21 undefined: filled with empty value */
+	if (trace->type.bit21) {
+		*(__be32 *)data = cpu_to_be32(IOAM6_U32_UNAVAILABLE);
+		data += sizeof(__be32);
+	}
+
 	/* opaque state snapshot */
 	if (trace->type.bit22) {
 		if (!sc) {
@@ -791,16 +851,10 @@ void ioam6_fill_trace_data(struct sk_buff *skb,
 	struct ioam6_schema *sc;
 	u8 sclen = 0;
 
-	/* Skip if Overflow flag is set OR
-	 * if an unknown type (bit 12-21) is set
+	/* Skip if Overflow flag is set
 	 */
-	if (trace->overflow ||
-	    trace->type.bit12 | trace->type.bit13 | trace->type.bit14 |
-	    trace->type.bit15 | trace->type.bit16 | trace->type.bit17 |
-	    trace->type.bit18 | trace->type.bit19 | trace->type.bit20 |
-	    trace->type.bit21) {
+	if (trace->overflow)
 		return;
-	}
 
 	/* NodeLen does not include Opaque State Snapshot length. We need to
 	 * take it into account if the corresponding bit is set (bit 22) and
diff --git a/net/ipv6/ioam6_iptunnel.c b/net/ipv6/ioam6_iptunnel.c
index f9ee04541c17..9b7b726f8f45 100644
--- a/net/ipv6/ioam6_iptunnel.c
+++ b/net/ipv6/ioam6_iptunnel.c
@@ -75,7 +75,11 @@ static bool ioam6_validate_trace_hdr(struct ioam6_trace_hdr *trace)
 	u32 fields;
 
 	if (!trace->type_be32 || !trace->remlen ||
-	    trace->remlen > IOAM6_TRACE_DATA_SIZE_MAX / 4)
+	    trace->remlen > IOAM6_TRACE_DATA_SIZE_MAX / 4 ||
+	    trace->type.bit12 | trace->type.bit13 | trace->type.bit14 |
+	    trace->type.bit15 | trace->type.bit16 | trace->type.bit17 |
+	    trace->type.bit18 | trace->type.bit19 | trace->type.bit20 |
+	    trace->type.bit21)
 		return false;
 
 	trace->nodelen = 0;