git: ad2a0aec2954 - main - nhop: hash ifnet pointer instead of if_index

The branch main has been updated by glebius:

URL: https://cgit.FreeBSD.org/src/commit/?id=ad2a0aec295478e750158b8985422f15deee0e54

commit ad2a0aec295478e750158b8985422f15deee0e54
Author:     Gleb Smirnoff <glebius@FreeBSD.org>
AuthorDate: 2021-12-04 18:05:46 +0000
Commit:     Gleb Smirnoff <glebius@FreeBSD.org>
CommitDate: 2021-12-04 18:05:46 +0000

    nhop: hash ifnet pointer instead of if_index
    
    Yet another problem created by VIMAGE/if_vmove/epair design that
    relocates ifnet between vnets and changes if_index.  Since if_index
    changes, nhop hash values also changes, unlink_nhop() isn't able to
    find entry in hash and leaks the nhop.  Since nhop references ifnet,
    the latter is also leaked.  As result running network tests leaks
    memory on every single test that creates vnet jail.
    
    While here, rewrite whole hash_priv() to use static initializer,
    per Alexander's suggestion.
    
    Reviewed by:    melifaro
---
 sys/net/route/nhop.c | 30 ++++++++++++------------------
 1 file changed, 12 insertions(+), 18 deletions(-)

diff --git a/sys/net/route/nhop.c b/sys/net/route/nhop.c
index ab5e393ae56a..531eae03638f 100644
--- a/sys/net/route/nhop.c
+++ b/sys/net/route/nhop.c
@@ -183,13 +183,13 @@ nhops_destroy_rib(struct rib_head *rh)
  * With that in mind, hash nexthops by the combination of the interface
  *  and GW IP address.
  *
- * To optimize hash calculation, ignore higher bytes of ifindex, as they
- *  give very little entropy.
+ * To optimize hash calculation, ignore lower bits of ifnet pointer,
+ * as they  give very little entropy.
  * Similarly, use lower 4 bytes of IPv6 address to distinguish between the
  *  neighbors.
  */
 struct _hash_data {
-	uint16_t	ifindex;
+	uint16_t	ifentropy;
 	uint8_t		family;
 	uint8_t		nh_type;
 	uint32_t	gw_addr;
@@ -210,21 +210,15 @@ djb_hash(const unsigned char *h, const int len)
 static uint32_t
 hash_priv(const struct nhop_priv *priv)
 {
-	struct nhop_object *nh;
-	uint16_t ifindex;
-	struct _hash_data key;
-
-	nh = priv->nh;
-	ifindex = nh->nh_ifp->if_index & 0xFFFF;
-	memset(&key, 0, sizeof(key));
-
-	key.ifindex = ifindex;
-	key.family = nh->gw_sa.sa_family;
-	key.nh_type = priv->nh_type & 0xFF;
-	if (nh->gw_sa.sa_family == AF_INET6)
-		memcpy(&key.gw_addr, &nh->gw6_sa.sin6_addr.s6_addr32[3], 4);
-	else if (nh->gw_sa.sa_family == AF_INET)
-		memcpy(&key.gw_addr, &nh->gw4_sa.sin_addr, 4);
+	struct nhop_object *nh = priv->nh;
+	struct _hash_data key = {
+	    .ifentropy = (uint16_t)((((uintptr_t)nh->nh_ifp) >> 6) & 0xFFFF),
+	    .family = nh->gw_sa.sa_family,
+	    .nh_type = priv->nh_type & 0xFF,
+	    .gw_addr = (nh->gw_sa.sa_family == AF_INET6) ?
+		nh->gw6_sa.sin6_addr.s6_addr32[3] :
+		nh->gw4_sa.sin_addr.s_addr
+	};
 
 	return (uint32_t)(djb_hash((const unsigned char *)&key, sizeof(key)));
 }