[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>

2 files changed, 206 insertions, 3 deletions

diff --git a/net/xfrm/xfrm_algo.c b/net/xfrm/xfrm_algo.c
index 02e3ecf9585d..6cc15250de69 100644
--- a/net/xfrm/xfrm_algo.c
+++ b/net/xfrm/xfrm_algo.c
@@ -28,6 +28,105 @@
  * that instantiated crypto transforms have correct parameters for IPsec
  * purposes.
  */
+static struct xfrm_algo_desc aead_list[] = {
+{
+        .name = "rfc4106(gcm(aes))",
+
+        .uinfo = {
+                .aead = {
+                        .icv_truncbits = 64,
+                }
+        },
+
+        .desc = {
+                .sadb_alg_id = SADB_X_EALG_AES_GCM_ICV8,
+                .sadb_alg_ivlen = 8,
+                .sadb_alg_minbits = 128,
+                .sadb_alg_maxbits = 256
+        }
+},
+{
+        .name = "rfc4106(gcm(aes))",
+
+        .uinfo = {
+                .aead = {
+                        .icv_truncbits = 96,
+                }
+        },
+
+        .desc = {
+                .sadb_alg_id = SADB_X_EALG_AES_GCM_ICV12,
+                .sadb_alg_ivlen = 8,
+                .sadb_alg_minbits = 128,
+                .sadb_alg_maxbits = 256
+        }
+},
+{
+        .name = "rfc4106(gcm(aes))",
+
+        .uinfo = {
+                .aead = {
+                        .icv_truncbits = 128,
+                }
+        },
+
+        .desc = {
+                .sadb_alg_id = SADB_X_EALG_AES_GCM_ICV16,
+                .sadb_alg_ivlen = 8,
+                .sadb_alg_minbits = 128,
+                .sadb_alg_maxbits = 256
+        }
+},
+{
+        .name = "rfc4309(ccm(aes))",
+
+        .uinfo = {
+                .aead = {
+                        .icv_truncbits = 64,
+                }
+        },
+
+        .desc = {
+                .sadb_alg_id = SADB_X_EALG_AES_CCM_ICV8,
+                .sadb_alg_ivlen = 8,
+                .sadb_alg_minbits = 128,
+                .sadb_alg_maxbits = 256
+        }
+},
+{
+        .name = "rfc4309(ccm(aes))",
+
+        .uinfo = {
+                .aead = {
+                        .icv_truncbits = 96,
+                }
+        },
+
+        .desc = {
+                .sadb_alg_id = SADB_X_EALG_AES_CCM_ICV12,
+                .sadb_alg_ivlen = 8,
+                .sadb_alg_minbits = 128,
+                .sadb_alg_maxbits = 256
+        }
+},
+{
+        .name = "rfc4309(ccm(aes))",
+
+        .uinfo = {
+                .aead = {
+                        .icv_truncbits = 128,
+                }
+        },
+
+        .desc = {
+                .sadb_alg_id = SADB_X_EALG_AES_CCM_ICV16,
+                .sadb_alg_ivlen = 8,
+                .sadb_alg_minbits = 128,
+                .sadb_alg_maxbits = 256
+        }
+},
+};
+
 static struct xfrm_algo_desc aalg_list[] = {
 {
         .name = "hmac(digest_null)",
@@ -332,6 +431,11 @@ static struct xfrm_algo_desc calg_list[] = {
 },
 };
 
+static inline int aead_entries(void)
+{
+        return ARRAY_SIZE(aead_list);
+}
+
 static inline int aalg_entries(void)
 {
         return ARRAY_SIZE(aalg_list);
@@ -354,6 +458,13 @@ struct xfrm_algo_list {
         u32 mask;
 };
 
+static const struct xfrm_algo_list xfrm_aead_list = {
+        .algs = aead_list,
+        .entries = ARRAY_SIZE(aead_list),
+        .type = CRYPTO_ALG_TYPE_AEAD,
+        .mask = CRYPTO_ALG_TYPE_MASK,
+};
+
 static const struct xfrm_algo_list xfrm_aalg_list = {
         .algs = aalg_list,
         .entries = ARRAY_SIZE(aalg_list),
@@ -461,6 +572,33 @@ struct xfrm_algo_desc *xfrm_calg_get_byname(char *name, int probe)
 }
 EXPORT_SYMBOL_GPL(xfrm_calg_get_byname);
 
+struct xfrm_aead_name {
+        const char *name;
+        int icvbits;
+};
+
+static int xfrm_aead_name_match(const struct xfrm_algo_desc *entry,
+                                const void *data)
+{
+        const struct xfrm_aead_name *aead = data;
+        const char *name = aead->name;
+
+        return aead->icvbits == entry->uinfo.aead.icv_truncbits && name &&
+               !strcmp(name, entry->name);
+}
+
+struct xfrm_algo_desc *xfrm_aead_get_byname(char *name, int icv_len, int probe)
+{
+        struct xfrm_aead_name data = {
+                .name = name,
+                .icvbits = icv_len,
+        };
+
+        return xfrm_find_algo(&xfrm_aead_list, xfrm_aead_name_match, &data,
+                              probe);
+}
+EXPORT_SYMBOL_GPL(xfrm_aead_get_byname);
+
 struct xfrm_algo_desc *xfrm_aalg_get_byidx(unsigned int idx)
 {
         if (idx >= aalg_entries())
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index e0ccdf267813..78338079b7f5 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -31,6 +31,11 @@
 #include <linux/in6.h>
 #endif
 
+static inline int aead_len(struct xfrm_algo_aead *alg)
+{
+        return sizeof(*alg) + ((alg->alg_key_len + 7) / 8);
+}
+
 static int verify_one_alg(struct nlattr **attrs, enum xfrm_attr_type_t type)
 {
         struct nlattr *rt = attrs[type];
@@ -68,6 +73,22 @@ static int verify_one_alg(struct nlattr **attrs, enum xfrm_attr_type_t type)
         return 0;
 }
 
+static int verify_aead(struct nlattr **attrs)
+{
+        struct nlattr *rt = attrs[XFRMA_ALG_AEAD];
+        struct xfrm_algo_aead *algp;
+
+        if (!rt)
+                return 0;
+
+        algp = nla_data(rt);
+        if (nla_len(rt) < aead_len(algp))
+                return -EINVAL;
+
+        algp->alg_name[CRYPTO_MAX_ALG_NAME - 1] = '\0';
+        return 0;
+}
+
 static void verify_one_addr(struct nlattr **attrs, enum xfrm_attr_type_t type,
                            xfrm_address_t **addrp)
 {
@@ -119,20 +140,28 @@ static int verify_newsa_info(struct xfrm_usersa_info *p,
         switch (p->id.proto) {
         case IPPROTO_AH:
                 if (!attrs[XFRMA_ALG_AUTH]      ||
+                    attrs[XFRMA_ALG_AEAD]       ||
                     attrs[XFRMA_ALG_CRYPT]      ||
                     attrs[XFRMA_ALG_COMP])
                         goto out;
                 break;
 
         case IPPROTO_ESP:
-                if ((!attrs[XFRMA_ALG_AUTH] &&
-                     !attrs[XFRMA_ALG_CRYPT])   ||
-                    attrs[XFRMA_ALG_COMP])
+                if (attrs[XFRMA_ALG_COMP])
+                        goto out;
+                if (!attrs[XFRMA_ALG_AUTH] &&
+                    !attrs[XFRMA_ALG_CRYPT] &&
+                    !attrs[XFRMA_ALG_AEAD])
+                        goto out;
+                if ((attrs[XFRMA_ALG_AUTH] ||
+                     attrs[XFRMA_ALG_CRYPT]) &&
+                    attrs[XFRMA_ALG_AEAD])
                         goto out;
                 break;
 
         case IPPROTO_COMP:
                 if (!attrs[XFRMA_ALG_COMP]      ||
+                    attrs[XFRMA_ALG_AEAD]       ||
                     attrs[XFRMA_ALG_AUTH]       ||
                     attrs[XFRMA_ALG_CRYPT])
                         goto out;
@@ -143,6 +172,7 @@ static int verify_newsa_info(struct xfrm_usersa_info *p,
         case IPPROTO_ROUTING:
                 if (attrs[XFRMA_ALG_COMP]       ||
                     attrs[XFRMA_ALG_AUTH]       ||
+                    attrs[XFRMA_ALG_AEAD]       ||
                     attrs[XFRMA_ALG_CRYPT]      ||
                     attrs[XFRMA_ENCAP]          ||
                     attrs[XFRMA_SEC_CTX]        ||
@@ -155,6 +185,8 @@ static int verify_newsa_info(struct xfrm_usersa_info *p,
                 goto out;
         }
 
+        if ((err = verify_aead(attrs)))
+                goto out;
         if ((err = verify_one_alg(attrs, XFRMA_ALG_AUTH)))
                 goto out;
         if ((err = verify_one_alg(attrs, XFRMA_ALG_CRYPT)))
@@ -208,6 +240,31 @@ static int attach_one_algo(struct xfrm_algo **algpp, u8 *props,
         return 0;
 }
 
+static int attach_aead(struct xfrm_algo_aead **algpp, u8 *props,
+                       struct nlattr *rta)
+{
+        struct xfrm_algo_aead *p, *ualg;
+        struct xfrm_algo_desc *algo;
+
+        if (!rta)
+                return 0;
+
+        ualg = nla_data(rta);
+
+        algo = xfrm_aead_get_byname(ualg->alg_name, ualg->alg_icv_len, 1);
+        if (!algo)
+                return -ENOSYS;
+        *props = algo->desc.sadb_alg_id;
+
+        p = kmemdup(ualg, aead_len(ualg), GFP_KERNEL);
+        if (!p)
+                return -ENOMEM;
+
+        strcpy(p->alg_name, algo->name);
+        *algpp = p;
+        return 0;
+}
+
 static inline int xfrm_user_sec_ctx_size(struct xfrm_sec_ctx *xfrm_ctx)
 {
         int len = 0;
@@ -286,6 +343,9 @@ static struct xfrm_state *xfrm_state_construct(struct xfrm_usersa_info *p,
 
         copy_from_user_state(x, p);
 
+        if ((err = attach_aead(&x->aead, &x->props.ealgo,
+                               attrs[XFRMA_ALG_AEAD])))
+                goto error;
         if ((err = attach_one_algo(&x->aalg, &x->props.aalgo,
                                    xfrm_aalg_get_byname,
                                    attrs[XFRMA_ALG_AUTH])))
@@ -510,6 +570,8 @@ static int copy_to_user_state_extra(struct xfrm_state *x,
         if (x->lastused)
                 NLA_PUT_U64(skb, XFRMA_LASTUSED, x->lastused);
 
+        if (x->aead)
+                NLA_PUT(skb, XFRMA_ALG_AEAD, aead_len(x->aead), x->aead);
         if (x->aalg)
                 NLA_PUT(skb, XFRMA_ALG_AUTH, xfrm_alg_len(x->aalg), x->aalg);
         if (x->ealg)
@@ -1808,6 +1870,7 @@ static const int xfrm_msg_min[XFRM_NR_MSGTYPES] = {
 #undef XMSGSIZE
 
 static const struct nla_policy xfrma_policy[XFRMA_MAX+1] = {
+        [XFRMA_ALG_AEAD]        = { .len = sizeof(struct xfrm_algo_aead) },
         [XFRMA_ALG_AUTH]        = { .len = sizeof(struct xfrm_algo) },
         [XFRMA_ALG_CRYPT]       = { .len = sizeof(struct xfrm_algo) },
         [XFRMA_ALG_COMP]        = { .len = sizeof(struct xfrm_algo) },
@@ -1972,6 +2035,8 @@ static int xfrm_notify_sa_flush(struct km_event *c)
 static inline size_t xfrm_sa_len(struct xfrm_state *x)
 {
         size_t l = 0;
+        if (x->aead)
+                l += nla_total_size(aead_len(x->aead));
         if (x->aalg)
                 l += nla_total_size(xfrm_alg_len(x->aalg));
         if (x->ealg)