[IPSEC]: Document that policy direction is derived from the index.

Here is a patch that adds a helper called xfrm_policy_id2dir to
document the fact that the policy direction can be and is derived
from the index.

This is based on a patch by YOSHIFUJI Hideaki and 210313105@suda.edu.cn.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 15 insertions, 5 deletions

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 7564b2ce449f..b6e72f890c6c 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -931,4 +931,9 @@ static inline int xfrm_addr_cmp(xfrm_address_t *a, xfrm_address_t *b,
         }
 }
 
+static inline int xfrm_policy_id2dir(u32 index)
+{
+        return index & 7;
+}
+
 #endif  /* _NET_XFRM_H */
diff --git a/net/key/af_key.c b/net/key/af_key.c
index 50d0a31c3ba6..bbf0f69181ba 100644
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -2154,6 +2154,7 @@ out:
 
 static int pfkey_spdget(struct sock *sk, struct sk_buff *skb, struct sadb_msg *hdr, void **ext_hdrs)
 {
+        unsigned int dir;
         int err;
         struct sadb_x_policy *pol;
         struct xfrm_policy *xp;
@@ -2162,7 +2163,11 @@ static int pfkey_spdget(struct sock *sk, struct sk_buff *skb, struct sadb_msg *h
         if ((pol = ext_hdrs[SADB_X_EXT_POLICY-1]) == NULL)
                 return -EINVAL;
 
-        xp = xfrm_policy_byid(0, pol->sadb_x_policy_id,
+        dir = xfrm_policy_id2dir(pol->sadb_x_policy_id);
+        if (dir >= XFRM_POLICY_MAX)
+                return -EINVAL;
+
+        xp = xfrm_policy_byid(dir, pol->sadb_x_policy_id,
                               hdr->sadb_msg_type == SADB_X_SPDDELETE2);
         if (xp == NULL)
                 return -ENOENT;
@@ -2174,9 +2179,9 @@ static int pfkey_spdget(struct sock *sk, struct sk_buff *skb, struct sadb_msg *h
         if (hdr->sadb_msg_type == SADB_X_SPDDELETE2) {
                 c.data.byid = 1;
                 c.event = XFRM_MSG_DELPOLICY;
-                km_policy_notify(xp, pol->sadb_x_policy_dir-1, &c);
+                km_policy_notify(xp, dir, &c);
         } else {
-                err = key_pol_get_resp(sk, xp, hdr, pol->sadb_x_policy_dir-1);
+                err = key_pol_get_resp(sk, xp, hdr, dir);
         }
 
         xfrm_pol_put(xp);
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index c6a0d34fc295..061b44cc2451 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -163,7 +163,7 @@ static void xfrm_policy_timer(unsigned long data)
         if (xp->dead)
                 goto out;
 
-        dir = xp->index & 7;
+        dir = xfrm_policy_id2dir(xp->index);
 
         if (xp->lft.hard_add_expires_seconds) {
                 long tmo = xp->lft.hard_add_expires_seconds +
@@ -417,7 +417,7 @@ struct xfrm_policy *xfrm_policy_byid(int dir, u32 id, int delete)
         struct xfrm_policy *pol, **p;
 
         write_lock_bh(&xfrm_policy_lock);
-        for (p = &xfrm_policy_list[id & 7]; (pol=*p)!=NULL; p = &pol->next) {
+        for (p = &xfrm_policy_list[dir]; (pol=*p)!=NULL; p = &pol->next) {
                 if (pol->index == id) {
                         xfrm_pol_hold(pol);
                         if (delete)