Merge branch 'net-fib_rules-add-dscp-selector-support'

Ido Schimmel says:

====================
net: fib_rules: Add DSCP selector support

Currently, the kernel rejects IPv4 FIB rules that try to match on the
upper three DSCP bits:

 # ip -4 rule add tos 0x1c table 100
 # ip -4 rule add tos 0x3c table 100
 Error: Invalid tos.

The reason for that is that historically users of the FIB lookup API
only populated the lower three DSCP bits in the TOS field of the IPv4
flow key ('flowi4_tos'), which fits the TOS definition from the initial
IPv4 specification (RFC 791).

This is not very useful nowadays and instead some users want to be able
to match on the six bits DSCP field, which replaced the TOS and IP
precedence fields over 25 years ago (RFC 2474). In addition, the current
behavior differs between IPv4 and IPv6 which does allow users to match
on the entire DSCP field using the TOS selector.

Recent patchsets made sure that callers of the FIB lookup API now
populate the entire DSCP field in the IPv4 flow key. Therefore, it is
now possible to extend FIB rules to match on DSCP.

This is done by adding a new DSCP attribute which is implemented for
both IPv4 and IPv6 to provide user space programs a consistent behavior
between both address families.

The behavior of the old TOS selector is unchanged and IPv4 FIB rules
using it will only match on the lower three DSCP bits. The kernel will
reject rules that try to use both selectors.

Patch #1 adds the new DSCP attribute but rejects its usage.

Patches #2-#3 implement IPv4 and IPv6 support.

Patch #4 allows user space to use the new attribute.

Patches #5-#6 add selftests.
====================

Link: https://patch.msgid.link/20240911093748.3662015-1-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 90 insertions, 0 deletions

diff --git a/tools/testing/selftests/net/fib_rule_tests.sh b/tools/testing/selftests/net/fib_rule_tests.sh
index 53c5c1ad437e..1d58b3b87465 100755
--- a/tools/testing/selftests/net/fib_rule_tests.sh
+++ b/tools/testing/selftests/net/fib_rule_tests.sh
@@ -274,6 +274,23 @@ fib_rule6_test()
 			"$getnomatch" "ipproto ipv6-icmp match" \
 			"ipproto ipv6-tcp no match"
 	fi
+
+	fib_check_iproute_support "dscp" "tos"
+	if [ $? -eq 0 ]; then
+		match="dscp 0x3f"
+		getmatch="tos 0xfc"
+		getnomatch="tos 0xf4"
+		fib_rule6_test_match_n_redirect "$match" "$getmatch" \
+			"$getnomatch" "dscp redirect to table" \
+			"dscp no redirect to table"
+
+		match="dscp 0x3f"
+		getmatch="from $SRC_IP6 iif $DEV tos 0xfc"
+		getnomatch="from $SRC_IP6 iif $DEV tos 0xf4"
+		fib_rule6_test_match_n_redirect "$match" "$getmatch" \
+			"$getnomatch" "iif dscp redirect to table" \
+			"iif dscp no redirect to table"
+	fi
 }
 
 fib_rule6_vrf_test()
@@ -319,6 +336,34 @@ fib_rule6_connect_test()
 	log_test $? 1 "rule6 dsfield tcp no connect (dsfield 0x20)"
 
 	$IP -6 rule del dsfield 0x04 table $RTABLE_PEER
+
+	ip rule help 2>&1 | grep -q dscp
+	if [ $? -ne 0 ]; then
+		echo "SKIP: iproute2 iprule too old, missing dscp match"
+		cleanup_peer
+		return
+	fi
+
+	$IP -6 rule add dscp 0x3f table $RTABLE_PEER
+
+	nettest -q -6 -B -t 5 -N $testns -O $peerns -U -D -Q 0xfc \
+		-l 2001:db8::1:11 -r 2001:db8::1:11
+	log_test $? 0 "rule6 dscp udp connect"
+
+	nettest -q -6 -B -t 5 -N $testns -O $peerns -Q 0xfc \
+		-l 2001:db8::1:11 -r 2001:db8::1:11
+	log_test $? 0 "rule6 dscp tcp connect"
+
+	nettest -q -6 -B -t 5 -N $testns -O $peerns -U -D -Q 0xf4 \
+		-l 2001:db8::1:11 -r 2001:db8::1:11
+	log_test $? 1 "rule6 dscp udp no connect"
+
+	nettest -q -6 -B -t 5 -N $testns -O $peerns -Q 0xf4 \
+		-l 2001:db8::1:11 -r 2001:db8::1:11
+	log_test $? 1 "rule6 dscp tcp no connect"
+
+	$IP -6 rule del dscp 0x3f table $RTABLE_PEER
+
 	cleanup_peer
 }
 
@@ -468,6 +513,23 @@ fib_rule4_test()
 			"$getnomatch" "ipproto icmp match" \
 			"ipproto tcp no match"
 	fi
+
+	fib_check_iproute_support "dscp" "tos"
+	if [ $? -eq 0 ]; then
+		match="dscp 0x3f"
+		getmatch="tos 0xfc"
+		getnomatch="tos 0xf4"
+		fib_rule4_test_match_n_redirect "$match" "$getmatch" \
+			"$getnomatch" "dscp redirect to table" \
+			"dscp no redirect to table"
+
+		match="dscp 0x3f"
+		getmatch="from $SRC_IP iif $DEV tos 0xfc"
+		getnomatch="from $SRC_IP iif $DEV tos 0xf4"
+		fib_rule4_test_match_n_redirect "$match" "$getmatch" \
+			"$getnomatch" "iif dscp redirect to table" \
+			"iif dscp no redirect to table"
+	fi
 }
 
 fib_rule4_vrf_test()
@@ -513,6 +575,34 @@ fib_rule4_connect_test()
 	log_test $? 1 "rule4 dsfield tcp no connect (dsfield 0x20)"
 
 	$IP -4 rule del dsfield 0x04 table $RTABLE_PEER
+
+	ip rule help 2>&1 | grep -q dscp
+	if [ $? -ne 0 ]; then
+		echo "SKIP: iproute2 iprule too old, missing dscp match"
+		cleanup_peer
+		return
+	fi
+
+	$IP -4 rule add dscp 0x3f table $RTABLE_PEER
+
+	nettest -q -B -t 5 -N $testns -O $peerns -D -U -Q 0xfc \
+		-l 198.51.100.11 -r 198.51.100.11
+	log_test $? 0 "rule4 dscp udp connect"
+
+	nettest -q -B -t 5 -N $testns -O $peerns -Q 0xfc \
+		-l 198.51.100.11 -r 198.51.100.11
+	log_test $? 0 "rule4 dscp tcp connect"
+
+	nettest -q -B -t 5 -N $testns -O $peerns -D -U -Q 0xf4 \
+		-l 198.51.100.11 -r 198.51.100.11
+	log_test $? 1 "rule4 dscp udp no connect"
+
+	nettest -q -B -t 5 -N $testns -O $peerns -Q 0xf4 \
+		-l 198.51.100.11 -r 198.51.100.11
+	log_test $? 1 "rule4 dscp tcp no connect"
+
+	$IP -4 rule del dscp 0x3f table $RTABLE_PEER
+
 	cleanup_peer
 }
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