[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>

1 files changed, 8 insertions, 3 deletions

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);