[IPSEC]: Add support for combined mode algorithms

This patch adds support for combined mode algorithms with GCM being
the first algorithm supported.

Combined mode algorithms can be added through the xfrm_user interface
using the new algorithm payload type XFRMA_ALG_AEAD.  Each algorithms
is identified by its name and the ICV length.

For the purposes of matching algorithms in xfrm_tmpl structures,
combined mode algorithms occupy the same name space as encryption
algorithms.  This is in line with how they are negotiated using IKE.

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

1 files changed, 58 insertions, 13 deletions

diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index c4047223bfbe..fac4f102c9f9 100644
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -439,32 +439,53 @@ static void esp_destroy(struct xfrm_state *x)
         kfree(esp);
 }
 
-static int esp_init_state(struct xfrm_state *x)
+static int esp_init_aead(struct xfrm_state *x)
 {
-        struct esp_data *esp = NULL;
+        struct esp_data *esp = x->data;
+        struct crypto_aead *aead;
+        int err;
+
+        aead = crypto_alloc_aead(x->aead->alg_name, 0, 0);
+        err = PTR_ERR(aead);
+        if (IS_ERR(aead))
+                goto error;
+
+        esp->aead = aead;
+
+        err = crypto_aead_setkey(aead, x->aead->alg_key,
+                                 (x->aead->alg_key_len + 7) / 8);
+        if (err)
+                goto error;
+
+        err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8);
+        if (err)
+                goto error;
+
+error:
+        return err;
+}
+
+static int esp_init_authenc(struct xfrm_state *x)
+{
+        struct esp_data *esp = x->data;
         struct crypto_aead *aead;
         struct crypto_authenc_key_param *param;
         struct rtattr *rta;
         char *key;
         char *p;
         char authenc_name[CRYPTO_MAX_ALG_NAME];
-        u32 align;
         unsigned int keylen;
         int err;
 
+        err = -EINVAL;
         if (x->ealg == NULL)
-                return -EINVAL;
+                goto error;
 
+        err = -ENAMETOOLONG;
         if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, "authenc(%s,%s)",
                      x->aalg ? x->aalg->alg_name : "digest_null",
                      x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME)
-                return -ENAMETOOLONG;
-
-        esp = kzalloc(sizeof(*esp), GFP_KERNEL);
-        if (esp == NULL)
-                return -ENOMEM;
-
-        x->data = esp;
+                goto error;
 
         aead = crypto_alloc_aead(authenc_name, 0, 0);
         err = PTR_ERR(aead);
@@ -512,8 +533,6 @@ static int esp_init_state(struct xfrm_state *x)
                         goto free_key;
         }
 
-        esp->padlen = 0;
-
         param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8);
         memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8);
 
@@ -522,9 +541,35 @@ static int esp_init_state(struct xfrm_state *x)
 free_key:
         kfree(key);
 
+error:
+        return err;
+}
+
+static int esp_init_state(struct xfrm_state *x)
+{
+        struct esp_data *esp;
+        struct crypto_aead *aead;
+        u32 align;
+        int err;
+
+        esp = kzalloc(sizeof(*esp), GFP_KERNEL);
+        if (esp == NULL)
+                return -ENOMEM;
+
+        x->data = esp;
+
+        if (x->aead)
+                err = esp_init_aead(x);
+        else
+                err = esp_init_authenc(x);
+
         if (err)
                 goto error;
 
+        aead = esp->aead;
+
+        esp->padlen = 0;
+
         x->props.header_len = sizeof(struct ip_esp_hdr) +
                               crypto_aead_ivsize(aead);
         if (x->props.mode == XFRM_MODE_TUNNEL)