gss_krb5: add ability to have a keyed checksum (hmac)

Encryption types besides DES may use a keyed checksum (hmac).
Modify the make_checksum() function to allow for a key
and take care of enctype-specific processing such as truncating
the resulting hash.

Signed-off-by: Kevin Coffman <kwc@citi.umich.edu>
Signed-off-by: Steve Dickson <steved@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

6 files changed, 88 insertions, 34 deletions

diff --git a/include/linux/sunrpc/gss_krb5.h b/include/linux/sunrpc/gss_krb5.h
index f94935599d13..abf26efd44ac 100644
--- a/include/linux/sunrpc/gss_krb5.h
+++ b/include/linux/sunrpc/gss_krb5.h
@@ -41,6 +41,9 @@
 #include <linux/sunrpc/gss_err.h>
 #include <linux/sunrpc/gss_asn1.h>
 
+/* Maximum key length (in bytes) for the supported crypto algorithms*/
+#define GSS_KRB5_MAX_KEYLEN (32)
+
 /* Maximum checksum function output for the supported crypto algorithms */
 #define GSS_KRB5_MAX_CKSUM_LEN  (20)
 
@@ -74,6 +77,7 @@ struct krb5_ctx {
         const struct gss_krb5_enctype *gk5e; /* enctype-specific info */
         struct crypto_blkcipher *enc;
         struct crypto_blkcipher *seq;
+        u8                      cksum[GSS_KRB5_MAX_KEYLEN];
         s32                     endtime;
         u32                     seq_send;
         struct xdr_netobj       mech_used;
@@ -159,9 +163,10 @@ enum seal_alg {
         + GSS_KRB5_TOK_HDR_LEN                                   \
         + GSS_KRB5_MAX_CKSUM_LEN)
 
-s32
-make_checksum(char *, char *header, int hdrlen, struct xdr_buf *body,
-                   int body_offset, struct xdr_netobj *cksum);
+u32
+make_checksum(struct krb5_ctx *kctx, char *header, int hdrlen,
+                struct xdr_buf *body, int body_offset, u8 *cksumkey,
+                struct xdr_netobj *cksumout);
 
 u32 gss_get_mic_kerberos(struct gss_ctx *, struct xdr_buf *,
                 struct xdr_netobj *);
diff --git a/net/sunrpc/auth_gss/gss_krb5_crypto.c b/net/sunrpc/auth_gss/gss_krb5_crypto.c
index ccd5236953f7..cae04d7a45a5 100644
--- a/net/sunrpc/auth_gss/gss_krb5_crypto.c
+++ b/net/sunrpc/auth_gss/gss_krb5_crypto.c
@@ -123,21 +123,42 @@ checksummer(struct scatterlist *sg, void *data)
         return crypto_hash_update(desc, sg, sg->length);
 }
 
-/* checksum the plaintext data and hdrlen bytes of the token header */
-s32
-make_checksum(char *cksumname, char *header, int hdrlen, struct xdr_buf *body,
-                   int body_offset, struct xdr_netobj *cksum)
+/*
+ * checksum the plaintext data and hdrlen bytes of the token header
+ * The checksum is performed over the first 8 bytes of the
+ * gss token header and then over the data body
+ */
+u32
+make_checksum(struct krb5_ctx *kctx, char *header, int hdrlen,
+              struct xdr_buf *body, int body_offset, u8 *cksumkey,
+              struct xdr_netobj *cksumout)
 {
-        struct hash_desc                desc; /* XXX add to ctx? */
+        struct hash_desc                desc;
         struct scatterlist              sg[1];
         int err;
+        u8 checksumdata[GSS_KRB5_MAX_CKSUM_LEN];
+        unsigned int checksumlen;
+
+        if (cksumout->len < kctx->gk5e->cksumlength) {
+                dprintk("%s: checksum buffer length, %u, too small for %s\n",
+                        __func__, cksumout->len, kctx->gk5e->name);
+                return GSS_S_FAILURE;
+        }
 
-        desc.tfm = crypto_alloc_hash(cksumname, 0, CRYPTO_ALG_ASYNC);
+        desc.tfm = crypto_alloc_hash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
         if (IS_ERR(desc.tfm))
                 return GSS_S_FAILURE;
-        cksum->len = crypto_hash_digestsize(desc.tfm);
         desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 
+        checksumlen = crypto_hash_digestsize(desc.tfm);
+
+        if (cksumkey != NULL) {
+                err = crypto_hash_setkey(desc.tfm, cksumkey,
+                                         kctx->gk5e->keylength);
+                if (err)
+                        goto out;
+        }
+
         err = crypto_hash_init(&desc);
         if (err)
                 goto out;
@@ -149,8 +170,25 @@ make_checksum(char *cksumname, char *header, int hdrlen, struct xdr_buf *body,
                               checksummer, &desc);
         if (err)
                 goto out;
-        err = crypto_hash_final(&desc, cksum->data);
+        err = crypto_hash_final(&desc, checksumdata);
+        if (err)
+                goto out;
 
+        switch (kctx->gk5e->ctype) {
+        case CKSUMTYPE_RSA_MD5:
+                err = kctx->gk5e->encrypt(kctx->seq, NULL, checksumdata,
+                                          checksumdata, checksumlen);
+                if (err)
+                        goto out;
+                memcpy(cksumout->data,
+                       checksumdata + checksumlen - kctx->gk5e->cksumlength,
+                       kctx->gk5e->cksumlength);
+                break;
+        default:
+                BUG();
+                break;
+        }
+        cksumout->len = kctx->gk5e->cksumlength;
 out:
         crypto_free_hash(desc.tfm);
         return err ? GSS_S_FAILURE : 0;
diff --git a/net/sunrpc/auth_gss/gss_krb5_mech.c b/net/sunrpc/auth_gss/gss_krb5_mech.c
index a66eb706aeb7..6f93f4752be4 100644
--- a/net/sunrpc/auth_gss/gss_krb5_mech.c
+++ b/net/sunrpc/auth_gss/gss_krb5_mech.c
@@ -66,6 +66,7 @@ static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {
           .keylength = 8,
           .blocksize = 8,
           .cksumlength = 8,
+          .keyed_cksum = 0,
         },
 };
 
diff --git a/net/sunrpc/auth_gss/gss_krb5_seal.c b/net/sunrpc/auth_gss/gss_krb5_seal.c
index 46c6f44e5c3f..cd512719092b 100644
--- a/net/sunrpc/auth_gss/gss_krb5_seal.c
+++ b/net/sunrpc/auth_gss/gss_krb5_seal.c
@@ -101,6 +101,7 @@ gss_get_mic_v1(struct krb5_ctx *ctx, struct xdr_buf *text,
         void                    *ptr;
         s32                     now;
         u32                     seq_send;
+        u8                      *cksumkey;
 
         dprintk("RPC:       %s\n", __func__);
         BUG_ON(ctx == NULL);
@@ -109,15 +110,15 @@ gss_get_mic_v1(struct krb5_ctx *ctx, struct xdr_buf *text,
 
         ptr = setup_token(ctx, token);
 
-        if (make_checksum((char *)ctx->gk5e->cksum_name, ptr, 8,
-                                                text, 0, &md5cksum))
-                return GSS_S_FAILURE;
+        if (ctx->gk5e->keyed_cksum)
+                cksumkey = ctx->cksum;
+        else
+                cksumkey = NULL;
 
-        if (krb5_encrypt(ctx->seq, NULL, md5cksum.data,
-                          md5cksum.data, md5cksum.len))
+        if (make_checksum(ctx, ptr, 8, text, 0, cksumkey, &md5cksum))
                 return GSS_S_FAILURE;
 
-        memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data + md5cksum.len - 8, 8);
+        memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len);
 
         spin_lock(&krb5_seq_lock);
         seq_send = ctx->seq_send++;
diff --git a/net/sunrpc/auth_gss/gss_krb5_unseal.c b/net/sunrpc/auth_gss/gss_krb5_unseal.c
index 10ee641a39d0..7515bffddf15 100644
--- a/net/sunrpc/auth_gss/gss_krb5_unseal.c
+++ b/net/sunrpc/auth_gss/gss_krb5_unseal.c
@@ -84,6 +84,7 @@ gss_verify_mic_v1(struct krb5_ctx *ctx,
         u32                     seqnum;
         unsigned char           *ptr = (unsigned char *)read_token->data;
         int                     bodysize;
+        u8                      *cksumkey;
 
         dprintk("RPC:       krb5_read_token\n");
 
@@ -108,14 +109,16 @@ gss_verify_mic_v1(struct krb5_ctx *ctx,
         if ((ptr[6] != 0xff) || (ptr[7] != 0xff))
                 return GSS_S_DEFECTIVE_TOKEN;
 
-        if (make_checksum((char *)ctx->gk5e->cksum_name, ptr, 8,
-                                        message_buffer, 0, &md5cksum))
-                return GSS_S_FAILURE;
+        if (ctx->gk5e->keyed_cksum)
+                cksumkey = ctx->cksum;
+        else
+                cksumkey = NULL;
 
-        if (krb5_encrypt(ctx->seq, NULL, md5cksum.data, md5cksum.data, 16))
+        if (make_checksum(ctx, ptr, 8, message_buffer, 0,
+                          cksumkey, &md5cksum))
                 return GSS_S_FAILURE;
 
-        if (memcmp(md5cksum.data + 8, ptr + GSS_KRB5_TOK_HDR_LEN,
+        if (memcmp(md5cksum.data, ptr + GSS_KRB5_TOK_HDR_LEN,
                                         ctx->gk5e->cksumlength))
                 return GSS_S_BAD_SIG;
 
diff --git a/net/sunrpc/auth_gss/gss_krb5_wrap.c b/net/sunrpc/auth_gss/gss_krb5_wrap.c
index 7188891bcc33..2eb3046a84ea 100644
--- a/net/sunrpc/auth_gss/gss_krb5_wrap.c
+++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c
@@ -167,6 +167,7 @@ gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset,
         int                     headlen;
         struct page             **tmp_pages;
         u32                     seq_send;
+        u8                      *cksumkey;
 
         dprintk("RPC:       %s\n", __func__);
 
@@ -205,18 +206,20 @@ gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset,
 
         make_confounder(msg_start, blocksize);
 
+        if (kctx->gk5e->keyed_cksum)
+                cksumkey = kctx->cksum;
+        else
+                cksumkey = NULL;
+
         /* XXXJBF: UGH!: */
         tmp_pages = buf->pages;
         buf->pages = pages;
-        if (make_checksum((char *)kctx->gk5e->cksum_name, ptr, 8, buf,
-                                offset + headlen - blocksize, &md5cksum))
+        if (make_checksum(kctx, ptr, 8, buf, offset + headlen - blocksize,
+                                        cksumkey, &md5cksum))
                 return GSS_S_FAILURE;
         buf->pages = tmp_pages;
 
-        if (krb5_encrypt(kctx->seq, NULL, md5cksum.data,
-                          md5cksum.data, md5cksum.len))
-                return GSS_S_FAILURE;
-        memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data + md5cksum.len - 8, 8);
+        memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len);
 
         spin_lock(&krb5_seq_lock);
         seq_send = kctx->seq_send++;
@@ -252,6 +255,7 @@ gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf)
         int                     data_len;
         int                     blocksize;
         int                     crypt_offset;
+        u8                      *cksumkey;
 
         dprintk("RPC:       gss_unwrap_kerberos\n");
 
@@ -288,15 +292,17 @@ gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf)
         if (gss_decrypt_xdr_buf(kctx->enc, buf, crypt_offset))
                 return GSS_S_DEFECTIVE_TOKEN;
 
-        if (make_checksum((char *)kctx->gk5e->cksum_name, ptr, 8, buf,
-                                                crypt_offset, &md5cksum))
-                return GSS_S_FAILURE;
+        if (kctx->gk5e->keyed_cksum)
+                cksumkey = kctx->cksum;
+        else
+                cksumkey = NULL;
 
-        if (krb5_encrypt(kctx->seq, NULL, md5cksum.data,
-                           md5cksum.data, md5cksum.len))
+        if (make_checksum(kctx, ptr, 8, buf, crypt_offset,
+                                                cksumkey, &md5cksum))
                 return GSS_S_FAILURE;
 
-        if (memcmp(md5cksum.data + 8, ptr + GSS_KRB5_TOK_HDR_LEN, 8))
+        if (memcmp(md5cksum.data, ptr + GSS_KRB5_TOK_HDR_LEN,
+                                                kctx->gk5e->cksumlength))
                 return GSS_S_BAD_SIG;
 
         /* it got through unscathed.  Make sure the context is unexpired */