Use the new dscp_t type to replace the fc_tos field of fib_config, to ensure IPv4 routes aren't influenced by ECN bits when configured with non-zero rtm_tos.
Before this patch, IPv4 routes specifying an rtm_tos with some of the ECN bits set were accepted. However they wouldn't work (never match) as IPv4 normally clears the ECN bits with IPTOS_RT_MASK before doing a FIB lookup (although a few buggy code paths don't).
After this patch, IPv4 routes specifying an rtm_tos with any ECN bit set is rejected.
Note: IPv6 routes ignore rtm_tos altogether, any rtm_tos is accepted, but treated as if it were 0.
Signed-off-by: Guillaume Nault gnault@redhat.com --- Shuah, FYI, this is the patch I was refering to in our discussion about testing invalid tos values: https://lore.kernel.org/netdev/20220202232555.GC15826@pc-4.home/
include/net/ip_fib.h | 3 +- net/ipv4/fib_frontend.c | 11 +++- net/ipv4/fib_trie.c | 7 ++- tools/testing/selftests/net/fib_tests.sh | 76 ++++++++++++++++++++++++ 4 files changed, 93 insertions(+), 4 deletions(-)
diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h index c4297704bbcb..6a82bcb8813b 100644 --- a/include/net/ip_fib.h +++ b/include/net/ip_fib.h @@ -17,6 +17,7 @@ #include <linux/rcupdate.h> #include <net/fib_notifier.h> #include <net/fib_rules.h> +#include <net/inet_dscp.h> #include <net/inetpeer.h> #include <linux/percpu.h> #include <linux/notifier.h> @@ -24,7 +25,7 @@
struct fib_config { u8 fc_dst_len; - u8 fc_tos; + dscp_t fc_dscp; u8 fc_protocol; u8 fc_scope; u8 fc_type; diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c index 4d61ddd8a0ec..c60e1d1ed2b0 100644 --- a/net/ipv4/fib_frontend.c +++ b/net/ipv4/fib_frontend.c @@ -32,6 +32,7 @@ #include <linux/list.h> #include <linux/slab.h>
+#include <net/inet_dscp.h> #include <net/ip.h> #include <net/protocol.h> #include <net/route.h> @@ -735,8 +736,16 @@ static int rtm_to_fib_config(struct net *net, struct sk_buff *skb, memset(cfg, 0, sizeof(*cfg));
rtm = nlmsg_data(nlh); + + if (!inet_validate_dscp(rtm->rtm_tos)) { + NL_SET_ERR_MSG(extack, + "Invalid dsfield (tos): ECN bits must be 0"); + err = -EINVAL; + goto errout; + } + cfg->fc_dscp = inet_dsfield_to_dscp(rtm->rtm_tos); + cfg->fc_dst_len = rtm->rtm_dst_len; - cfg->fc_tos = rtm->rtm_tos; cfg->fc_table = rtm->rtm_table; cfg->fc_protocol = rtm->rtm_protocol; cfg->fc_scope = rtm->rtm_scope; diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index 8060524f4256..d937eeebb812 100644 --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -61,6 +61,7 @@ #include <linux/vmalloc.h> #include <linux/notifier.h> #include <net/net_namespace.h> +#include <net/inet_dscp.h> #include <net/ip.h> #include <net/protocol.h> #include <net/route.h> @@ -1210,9 +1211,9 @@ int fib_table_insert(struct net *net, struct fib_table *tb, struct fib_info *fi; u8 plen = cfg->fc_dst_len; u8 slen = KEYLENGTH - plen; - u8 tos = cfg->fc_tos; u32 key; int err; + u8 tos;
key = ntohl(cfg->fc_dst);
@@ -1227,6 +1228,7 @@ int fib_table_insert(struct net *net, struct fib_table *tb, goto err; }
+ tos = inet_dscp_to_dsfield(cfg->fc_dscp); l = fib_find_node(t, &tp, key); fa = l ? fib_find_alias(&l->leaf, slen, tos, fi->fib_priority, tb->tb_id, false) : NULL; @@ -1703,8 +1705,8 @@ int fib_table_delete(struct net *net, struct fib_table *tb, struct key_vector *l, *tp; u8 plen = cfg->fc_dst_len; u8 slen = KEYLENGTH - plen; - u8 tos = cfg->fc_tos; u32 key; + u8 tos;
key = ntohl(cfg->fc_dst);
@@ -1715,6 +1717,7 @@ int fib_table_delete(struct net *net, struct fib_table *tb, if (!l) return -ESRCH;
+ tos = inet_dscp_to_dsfield(cfg->fc_dscp); fa = fib_find_alias(&l->leaf, slen, tos, 0, tb->tb_id, false); if (!fa) return -ESRCH; diff --git a/tools/testing/selftests/net/fib_tests.sh b/tools/testing/selftests/net/fib_tests.sh index 996af1ae3d3d..bb73235976b3 100755 --- a/tools/testing/selftests/net/fib_tests.sh +++ b/tools/testing/selftests/net/fib_tests.sh @@ -1447,6 +1447,81 @@ ipv4_local_rt_cache() log_test $? 0 "Cached route removed from VRF port device" }
+ipv4_rt_dsfield() +{ + echo + echo "IPv4 route with dsfield tests" + + run_cmd "$IP route flush 172.16.102.0/24" + + # New routes should reject dsfield options that interfere with ECN + run_cmd "$IP route add 172.16.102.0/24 dsfield 0x01 via 172.16.101.2" + log_test $? 2 "Reject route with dsfield 0x01" + + run_cmd "$IP route add 172.16.102.0/24 dsfield 0x02 via 172.16.101.2" + log_test $? 2 "Reject route with dsfield 0x02" + + run_cmd "$IP route add 172.16.102.0/24 dsfield 0x03 via 172.16.101.2" + log_test $? 2 "Reject route with dsfield 0x03" + + # A generic route that doesn't take DSCP into account + run_cmd "$IP route add 172.16.102.0/24 via 172.16.101.2" + + # A more specific route for DSCP 0x10 + run_cmd "$IP route add 172.16.102.0/24 dsfield 0x10 via 172.16.103.2" + + # DSCP 0x10 should match the specific route, no matter the ECN bits + $IP route get fibmatch 172.16.102.1 dsfield 0x10 | \ + grep -q "via 172.16.103.2" + log_test $? 0 "IPv4 route with DSCP and ECN:Not-ECT" + + $IP route get fibmatch 172.16.102.1 dsfield 0x11 | \ + grep -q "via 172.16.103.2" + log_test $? 0 "IPv4 route with DSCP and ECN:ECT(1)" + + $IP route get fibmatch 172.16.102.1 dsfield 0x12 | \ + grep -q "via 172.16.103.2" + log_test $? 0 "IPv4 route with DSCP and ECN:ECT(0)" + + $IP route get fibmatch 172.16.102.1 dsfield 0x13 | \ + grep -q "via 172.16.103.2" + log_test $? 0 "IPv4 route with DSCP and ECN:CE" + + # Unknown DSCP should match the generic route, no matter the ECN bits + $IP route get fibmatch 172.16.102.1 dsfield 0x14 | \ + grep -q "via 172.16.101.2" + log_test $? 0 "IPv4 route with unknown DSCP and ECN:Not-ECT" + + $IP route get fibmatch 172.16.102.1 dsfield 0x15 | \ + grep -q "via 172.16.101.2" + log_test $? 0 "IPv4 route with unknown DSCP and ECN:ECT(1)" + + $IP route get fibmatch 172.16.102.1 dsfield 0x16 | \ + grep -q "via 172.16.101.2" + log_test $? 0 "IPv4 route with unknown DSCP and ECN:ECT(0)" + + $IP route get fibmatch 172.16.102.1 dsfield 0x17 | \ + grep -q "via 172.16.101.2" + log_test $? 0 "IPv4 route with unknown DSCP and ECN:CE" + + # Null DSCP should match the generic route, no matter the ECN bits + $IP route get fibmatch 172.16.102.1 dsfield 0x00 | \ + grep -q "via 172.16.101.2" + log_test $? 0 "IPv4 route with no DSCP and ECN:Not-ECT" + + $IP route get fibmatch 172.16.102.1 dsfield 0x01 | \ + grep -q "via 172.16.101.2" + log_test $? 0 "IPv4 route with no DSCP and ECN:ECT(1)" + + $IP route get fibmatch 172.16.102.1 dsfield 0x02 | \ + grep -q "via 172.16.101.2" + log_test $? 0 "IPv4 route with no DSCP and ECN:ECT(0)" + + $IP route get fibmatch 172.16.102.1 dsfield 0x03 | \ + grep -q "via 172.16.101.2" + log_test $? 0 "IPv4 route with no DSCP and ECN:CE" +} + ipv4_route_test() { route_setup @@ -1454,6 +1529,7 @@ ipv4_route_test() ipv4_rt_add ipv4_rt_replace ipv4_local_rt_cache + ipv4_rt_dsfield
route_cleanup }