net: Handle different key sizes between address families in flow cache

With the conversion of struct flowi to a union of AF-specific structs, some
operations on the flow cache need to account for the exact size of the key.

Signed-off-by: David Ward <david.ward@ll.mit.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 36 insertions, 14 deletions

diff --git a/include/net/flow.h b/include/net/flow.h
index 2ec377d9ab9f..a09447749e2d 100644
--- a/include/net/flow.h
+++ b/include/net/flow.h
@@ -7,6 +7,7 @@
 #ifndef _NET_FLOW_H
 #define _NET_FLOW_H
 
+#include <linux/socket.h>
 #include <linux/in6.h>
 #include <linux/atomic.h>
 
@@ -161,6 +162,24 @@ static inline struct flowi *flowidn_to_flowi(struct flowidn *fldn)
         return container_of(fldn, struct flowi, u.dn);
 }
 
+typedef unsigned long flow_compare_t;
+
+static inline size_t flow_key_size(u16 family)
+{
+        switch (family) {
+        case AF_INET:
+                BUILD_BUG_ON(sizeof(struct flowi4) % sizeof(flow_compare_t));
+                return sizeof(struct flowi4) / sizeof(flow_compare_t);
+        case AF_INET6:
+                BUILD_BUG_ON(sizeof(struct flowi6) % sizeof(flow_compare_t));
+                return sizeof(struct flowi6) / sizeof(flow_compare_t);
+        case AF_DECnet:
+                BUILD_BUG_ON(sizeof(struct flowidn) % sizeof(flow_compare_t));
+                return sizeof(struct flowidn) / sizeof(flow_compare_t);
+        }
+        return 0;
+}
+
 #define FLOW_DIR_IN     0
 #define FLOW_DIR_OUT    1
 #define FLOW_DIR_FWD    2
diff --git a/net/core/flow.c b/net/core/flow.c
index 47b6d26c2afb..555a456efb07 100644
--- a/net/core/flow.c
+++ b/net/core/flow.c
@@ -173,29 +173,26 @@ static void flow_new_hash_rnd(struct flow_cache *fc,
 
 static u32 flow_hash_code(struct flow_cache *fc,
                           struct flow_cache_percpu *fcp,
-                          const struct flowi *key)
+                          const struct flowi *key,
+                          size_t keysize)
 {
         const u32 *k = (const u32 *) key;
+        const u32 length = keysize * sizeof(flow_compare_t) / sizeof(u32);
 
-        return jhash2(k, (sizeof(*key) / sizeof(u32)), fcp->hash_rnd)
+        return jhash2(k, length, fcp->hash_rnd)
                 & (flow_cache_hash_size(fc) - 1);
 }
 
-typedef unsigned long flow_compare_t;
-
 /* I hear what you're saying, use memcmp.  But memcmp cannot make
- * important assumptions that we can here, such as alignment and
- * constant size.
+ * important assumptions that we can here, such as alignment.
  */
-static int flow_key_compare(const struct flowi *key1, const struct flowi *key2)
+static int flow_key_compare(const struct flowi *key1, const struct flowi *key2,
+                            size_t keysize)
 {
         const flow_compare_t *k1, *k1_lim, *k2;
-        const int n_elem = sizeof(struct flowi) / sizeof(flow_compare_t);
-
-        BUILD_BUG_ON(sizeof(struct flowi) % sizeof(flow_compare_t));
 
         k1 = (const flow_compare_t *) key1;
-        k1_lim = k1 + n_elem;
+        k1_lim = k1 + keysize;
 
         k2 = (const flow_compare_t *) key2;
 
@@ -216,6 +213,7 @@ flow_cache_lookup(struct net *net, const struct flowi *key, u16 family, u8 dir,
         struct flow_cache_entry *fle, *tfle;
         struct hlist_node *entry;
         struct flow_cache_object *flo;
+        size_t keysize;
         unsigned int hash;
 
         local_bh_disable();
@@ -223,6 +221,11 @@ flow_cache_lookup(struct net *net, const struct flowi *key, u16 family, u8 dir,
 
         fle = NULL;
         flo = NULL;
+
+        keysize = flow_key_size(family);
+        if (!keysize)
+                goto nocache;
+
         /* Packet really early in init?  Making flow_cache_init a
          * pre-smp initcall would solve this.  --RR */
         if (!fcp->hash_table)
@@ -231,12 +234,12 @@ flow_cache_lookup(struct net *net, const struct flowi *key, u16 family, u8 dir,
         if (fcp->hash_rnd_recalc)
                 flow_new_hash_rnd(fc, fcp);
 
-        hash = flow_hash_code(fc, fcp, key);
+        hash = flow_hash_code(fc, fcp, key, keysize);
         hlist_for_each_entry(tfle, entry, &fcp->hash_table[hash], u.hlist) {
                 if (tfle->net == net &&
                     tfle->family == family &&
                     tfle->dir == dir &&
-                    flow_key_compare(key, &tfle->key) == 0) {
+                    flow_key_compare(key, &tfle->key, keysize) == 0) {
                         fle = tfle;
                         break;
                 }
@@ -251,7 +254,7 @@ flow_cache_lookup(struct net *net, const struct flowi *key, u16 family, u8 dir,
                         fle->net = net;
                         fle->family = family;
                         fle->dir = dir;
-                        memcpy(&fle->key, key, sizeof(*key));
+                        memcpy(&fle->key, key, keysize * sizeof(flow_compare_t));
                         fle->object = NULL;
                         hlist_add_head(&fle->u.hlist, &fcp->hash_table[hash]);
                         fcp->hash_count++;