type safety for kernel version

Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: If05c0c5383dceeb65964143f5574d2ee1a484907
diff --git a/bpf_progs/bpf_net_helpers.h b/bpf_progs/bpf_net_helpers.h
index 2383d95..1122f50 100644
--- a/bpf_progs/bpf_net_helpers.h
+++ b/bpf_progs/bpf_net_helpers.h
@@ -102,5 +102,3 @@
 // constants for passing in to 'bool updatetime'
 static const bool NO_UPDATETIME = false;
 static const bool UPDATETIME = true;
-
-#define KVER_4_14 KVER(4, 14, 0)
diff --git a/bpf_progs/clatd.c b/bpf_progs/clatd.c
index 8f0ff84..ae63d2a 100644
--- a/bpf_progs/clatd.c
+++ b/bpf_progs/clatd.c
@@ -56,7 +56,7 @@
 
 static inline __always_inline int nat64(struct __sk_buff* skb,
                                         const bool is_ethernet,
-                                        const unsigned kver) {
+                                        const struct kver_uint kver) {
     // Require ethernet dst mac address to be our unicast address.
     if (is_ethernet && (skb->pkt_type != PACKET_HOST)) return TC_ACT_PIPE;
 
@@ -115,7 +115,7 @@
 
     if (proto == IPPROTO_FRAGMENT) {
         // Fragment handling requires bpf_skb_adjust_room which is 4.14+
-        if (kver < KVER_4_14) return TC_ACT_PIPE;
+        if (!KVER_IS_AT_LEAST(kver, 4, 14, 0)) return TC_ACT_PIPE;
 
         // Must have (ethernet and) ipv6 header and ipv6 fragment extension header
         if (data + l2_header_size + sizeof(*ip6) + sizeof(struct frag_hdr) > data_end)
@@ -233,7 +233,7 @@
     //
     // Note: we currently have no TreeHugger coverage for 4.9-T devices (there are no such
     // Pixel or cuttlefish devices), so likely you won't notice for months if this breaks...
-    if (kver >= KVER_4_14 && frag_off != htons(IP_DF)) {
+    if (KVER_IS_AT_LEAST(kver, 4, 14, 0) && frag_off != htons(IP_DF)) {
         // If we're converting an IPv6 Fragment, we need to trim off 8 more bytes
         // We're beyond recovery on error here... but hard to imagine how this could fail.
         if (bpf_skb_adjust_room(skb, -(__s32)sizeof(struct frag_hdr), BPF_ADJ_ROOM_NET, /*flags*/0))
diff --git a/bpf_progs/netd.c b/bpf_progs/netd.c
index 7a48e8c..7800fbc 100644
--- a/bpf_progs/netd.c
+++ b/bpf_progs/netd.c
@@ -179,7 +179,7 @@
     static __always_inline inline void update_##the_stats_map(const struct __sk_buff* const skb, \
                                                               const TypeOfKey* const key,        \
                                                               const bool egress,                 \
-                                                              const unsigned kver) {             \
+                                                              const struct kver_uint kver) {     \
         StatsValue* value = bpf_##the_stats_map##_lookup_elem(key);                              \
         if (!value) {                                                                            \
             StatsValue newValue = {};                                                            \
@@ -219,7 +219,7 @@
                                                          const int L3_off,
                                                          void* const to,
                                                          const int len,
-                                                         const unsigned kver) {
+                                                         const struct kver_uint kver) {
     // 'kver' (here and throughout) is the compile time guaranteed minimum kernel version,
     // ie. we're building (a version of) the bpf program for kver (or newer!) kernels.
     //
@@ -236,16 +236,16 @@
     //
     // For similar reasons this will fail with non-offloaded VLAN tags on < 4.19 kernels,
     // since those extend the ethernet header from 14 to 18 bytes.
-    return kver >= KVER(4, 19, 0)
+    return KVER_IS_AT_LEAST(kver, 4, 19, 0)
         ? bpf_skb_load_bytes_relative(skb, L3_off, to, len, BPF_HDR_START_NET)
         : bpf_skb_load_bytes(skb, L3_off, to, len);
 }
 
 static __always_inline inline void do_packet_tracing(
         const struct __sk_buff* const skb, const bool egress, const uint32_t uid,
-        const uint32_t tag, const bool enable_tracing, const unsigned kver) {
+        const uint32_t tag, const bool enable_tracing, const struct kver_uint kver) {
     if (!enable_tracing) return;
-    if (kver < KVER(5, 8, 0)) return;
+    if (!KVER_IS_AT_LEAST(kver, 5, 8, 0)) return;
 
     uint32_t mapKey = 0;
     bool* traceConfig = bpf_packet_trace_enabled_map_lookup_elem(&mapKey);
@@ -327,7 +327,7 @@
 }
 
 static __always_inline inline bool skip_owner_match(struct __sk_buff* skb, bool egress,
-                                                    const unsigned kver) {
+                                                    const struct kver_uint kver) {
     uint32_t flag = 0;
     if (skb->protocol == htons(ETH_P_IP)) {
         uint8_t proto;
@@ -372,11 +372,11 @@
 }
 
 static __always_inline inline bool ingress_should_discard(struct __sk_buff* skb,
-                                                          const unsigned kver) {
+                                                          const struct kver_uint kver) {
     // Require 4.19, since earlier kernels don't have bpf_skb_load_bytes_relative() which
     // provides relative to L3 header reads.  Without that we could fetch the wrong bytes.
     // Additionally earlier bpf verifiers are much harder to please.
-    if (kver < KVER(4, 19, 0)) return false;
+    if (!KVER_IS_AT_LEAST(kver, 4, 19, 0)) return false;
 
     IngressDiscardKey k = {};
     if (skb->protocol == htons(ETH_P_IP)) {
@@ -401,7 +401,7 @@
 }
 
 static __always_inline inline int bpf_owner_match(struct __sk_buff* skb, uint32_t uid,
-                                                  bool egress, const unsigned kver) {
+                                                  bool egress, const struct kver_uint kver) {
     if (is_system_uid(uid)) return PASS;
 
     if (skip_owner_match(skb, egress, kver)) return PASS;
@@ -435,7 +435,7 @@
                                                             const struct __sk_buff* const skb,
                                                             const StatsKey* const key,
                                                             const bool egress,
-                                                            const unsigned kver) {
+                                                            const struct kver_uint kver) {
     if (selectedMap == SELECT_MAP_A) {
         update_stats_map_A(skb, key, egress, kver);
     } else {
@@ -445,7 +445,7 @@
 
 static __always_inline inline int bpf_traffic_account(struct __sk_buff* skb, bool egress,
                                                       const bool enable_tracing,
-                                                      const unsigned kver) {
+                                                      const struct kver_uint kver) {
     uint32_t sock_uid = bpf_get_socket_uid(skb);
     uint64_t cookie = bpf_get_socket_cookie(skb);
     UidTagValue* utag = bpf_cookie_tag_map_lookup_elem(&cookie);
diff --git a/bpf_progs/offload.c b/bpf_progs/offload.c
index c752779..ae674ed 100644
--- a/bpf_progs/offload.c
+++ b/bpf_progs/offload.c
@@ -125,7 +125,7 @@
                    TETHERING_GID)
 
 static inline __always_inline int do_forward6(struct __sk_buff* skb, const bool is_ethernet,
-        const bool downstream, const unsigned kver) {
+        const bool downstream, const struct kver_uint kver) {
     // Must be meta-ethernet IPv6 frame
     if (skb->protocol != htons(ETH_P_IPV6)) return TC_ACT_PIPE;
 
@@ -358,7 +358,7 @@
         const int l2_header_size, void* data, const void* data_end,
         struct ethhdr* eth, struct iphdr* ip, const bool is_ethernet,
         const bool downstream, const bool updatetime, const bool is_tcp,
-        const unsigned kver) {
+        const struct kver_uint kver) {
     struct tcphdr* tcph = is_tcp ? (void*)(ip + 1) : NULL;
     struct udphdr* udph = is_tcp ? NULL : (void*)(ip + 1);
 
@@ -548,7 +548,7 @@
 }
 
 static inline __always_inline int do_forward4(struct __sk_buff* skb, const bool is_ethernet,
-        const bool downstream, const bool updatetime, const unsigned kver) {
+        const bool downstream, const bool updatetime, const struct kver_uint kver) {
     // Require ethernet dst mac address to be our unicast address.
     if (is_ethernet && (skb->pkt_type != PACKET_HOST)) return TC_ACT_PIPE;