[IPSEC] xfrm: Abstract out encapsulation modes

This patch adds the structure xfrm_mode.  It is meant to represent
the operations carried out by transport/tunnel modes.

By doing this we allow additional encapsulation modes to be added
without clogging up the xfrm_input/xfrm_output paths.

Candidate modes include 4-to-6 tunnel mode, 6-to-4 tunnel mode, and
BEET modes.

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

1 files changed, 83 insertions, 0 deletions

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 44b64a593c01..b8936926c24b 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -138,6 +138,89 @@ void xfrm_put_type(struct xfrm_type *type)
         module_put(type->owner);
 }
 
+int xfrm_register_mode(struct xfrm_mode *mode, int family)
+{
+        struct xfrm_policy_afinfo *afinfo;
+        struct xfrm_mode **modemap;
+        int err;
+
+        if (unlikely(mode->encap >= XFRM_MODE_MAX))
+                return -EINVAL;
+
+        afinfo = xfrm_policy_lock_afinfo(family);
+        if (unlikely(afinfo == NULL))
+                return -EAFNOSUPPORT;
+
+        err = -EEXIST;
+        modemap = afinfo->mode_map;
+        if (likely(modemap[mode->encap] == NULL)) {
+                modemap[mode->encap] = mode;
+                err = 0;
+        }
+
+        xfrm_policy_unlock_afinfo(afinfo);
+        return err;
+}
+EXPORT_SYMBOL(xfrm_register_mode);
+
+int xfrm_unregister_mode(struct xfrm_mode *mode, int family)
+{
+        struct xfrm_policy_afinfo *afinfo;
+        struct xfrm_mode **modemap;
+        int err;
+
+        if (unlikely(mode->encap >= XFRM_MODE_MAX))
+                return -EINVAL;
+
+        afinfo = xfrm_policy_lock_afinfo(family);
+        if (unlikely(afinfo == NULL))
+                return -EAFNOSUPPORT;
+
+        err = -ENOENT;
+        modemap = afinfo->mode_map;
+        if (likely(modemap[mode->encap] == mode)) {
+                modemap[mode->encap] = NULL;
+                err = 0;
+        }
+
+        xfrm_policy_unlock_afinfo(afinfo);
+        return err;
+}
+EXPORT_SYMBOL(xfrm_unregister_mode);
+
+struct xfrm_mode *xfrm_get_mode(unsigned int encap, int family)
+{
+        struct xfrm_policy_afinfo *afinfo;
+        struct xfrm_mode *mode;
+        int modload_attempted = 0;
+
+        if (unlikely(encap >= XFRM_MODE_MAX))
+                return NULL;
+
+retry:
+        afinfo = xfrm_policy_get_afinfo(family);
+        if (unlikely(afinfo == NULL))
+                return NULL;
+
+        mode = afinfo->mode_map[encap];
+        if (unlikely(mode && !try_module_get(mode->owner)))
+                mode = NULL;
+        if (!mode && !modload_attempted) {
+                xfrm_policy_put_afinfo(afinfo);
+                request_module("xfrm-mode-%d-%d", family, encap);
+                modload_attempted = 1;
+                goto retry;
+        }
+
+        xfrm_policy_put_afinfo(afinfo);
+        return mode;
+}
+
+void xfrm_put_mode(struct xfrm_mode *mode)
+{
+        module_put(mode->owner);
+}
+
 static inline unsigned long make_jiffies(long secs)
 {
         if (secs >= (MAX_SCHEDULE_TIMEOUT-1)/HZ)