gss_krb5: Introduce encryption type framework
Make the client and server code consistent regarding the extra buffer
space made available for the auth code when wrapping data.
Add some comments/documentation about the available buffer space
in the xdr_buf head and tail when gss_wrap is called.
Add a compile-time check to make sure we are not exceeding the available
buffer space.
Add a central function to shift head data.
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>
diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index c389ccf..75602ec 100644
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -61,7 +61,7 @@
# define RPCDBG_FACILITY RPCDBG_AUTH
#endif
-#define GSS_CRED_SLACK 1024
+#define GSS_CRED_SLACK (RPC_MAX_AUTH_SIZE * 2)
/* length of a krb5 verifier (48), plus data added before arguments when
* using integrity (two 4-byte integers): */
#define GSS_VERF_SLACK 100
diff --git a/net/sunrpc/auth_gss/gss_krb5_crypto.c b/net/sunrpc/auth_gss/gss_krb5_crypto.c
index e9b6361..746b3e1 100644
--- a/net/sunrpc/auth_gss/gss_krb5_crypto.c
+++ b/net/sunrpc/auth_gss/gss_krb5_crypto.c
@@ -325,3 +325,41 @@
return xdr_process_buf(buf, offset, buf->len - offset, decryptor, &desc);
}
+
+/*
+ * This function makes the assumption that it was ultimately called
+ * from gss_wrap().
+ *
+ * The client auth_gss code moves any existing tail data into a
+ * separate page before calling gss_wrap.
+ * The server svcauth_gss code ensures that both the head and the
+ * tail have slack space of RPC_MAX_AUTH_SIZE before calling gss_wrap.
+ *
+ * Even with that guarantee, this function may be called more than
+ * once in the processing of gss_wrap(). The best we can do is
+ * verify at compile-time (see GSS_KRB5_SLACK_CHECK) that the
+ * largest expected shift will fit within RPC_MAX_AUTH_SIZE.
+ * At run-time we can verify that a single invocation of this
+ * function doesn't attempt to use more the RPC_MAX_AUTH_SIZE.
+ */
+
+int
+xdr_extend_head(struct xdr_buf *buf, unsigned int base, unsigned int shiftlen)
+{
+ u8 *p;
+
+ if (shiftlen == 0)
+ return 0;
+
+ BUILD_BUG_ON(GSS_KRB5_MAX_SLACK_NEEDED > RPC_MAX_AUTH_SIZE);
+ BUG_ON(shiftlen > RPC_MAX_AUTH_SIZE);
+
+ p = buf->head[0].iov_base + base;
+
+ memmove(p + shiftlen, p, buf->head[0].iov_len - base);
+
+ buf->head[0].iov_len += shiftlen;
+ buf->len += shiftlen;
+
+ return 0;
+}
diff --git a/net/sunrpc/auth_gss/gss_krb5_wrap.c b/net/sunrpc/auth_gss/gss_krb5_wrap.c
index a6e9056..496281f 100644
--- a/net/sunrpc/auth_gss/gss_krb5_wrap.c
+++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c
@@ -155,11 +155,9 @@
ptr = buf->head[0].iov_base + offset;
/* shift data to make room for header. */
+ xdr_extend_head(buf, offset, headlen);
+
/* XXX Would be cleverer to encrypt while copying. */
- /* XXX bounds checking, slack, etc. */
- memmove(ptr + headlen, ptr, buf->head[0].iov_len - offset);
- buf->head[0].iov_len += headlen;
- buf->len += headlen;
BUG_ON((buf->len - offset - headlen) % blocksize);
g_make_token_header(&kctx->mech_used,
