RPCSEC_GSS: client-side privacy support

 Add the code to the client side to handle privacy.  This is dead code until
 we actually add privacy support to krb5.

 Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

net/sunrpc/auth_gss/auth_gss.c

@@ -43,6 +43,7 @@
 #include <linux/types.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
+#include <linux/pagemap.h>
 #include <linux/sunrpc/clnt.h>
 #include <linux/sunrpc/auth.h>
 #include <linux/sunrpc/auth_gss.h>
@@ -975,6 +976,114 @@ gss_wrap_req_integ(struct rpc_cred *cred, struct gss_cl_ctx *ctx,
 	return 0;
 }
 
+static void
+priv_release_snd_buf(struct rpc_rqst *rqstp)
+{
+	int i;
+
+	for (i=0; i < rqstp->rq_enc_pages_num; i++)
+		__free_page(rqstp->rq_enc_pages[i]);
+	kfree(rqstp->rq_enc_pages);
+}
+
+static int
+alloc_enc_pages(struct rpc_rqst *rqstp)
+{
+	struct xdr_buf *snd_buf = &rqstp->rq_snd_buf;
+	int first, last, i;
+
+	if (snd_buf->page_len == 0) {
+		rqstp->rq_enc_pages_num = 0;
+		return 0;
+	}
+
+	first = snd_buf->page_base >> PAGE_CACHE_SHIFT;
+	last = (snd_buf->page_base + snd_buf->page_len - 1) >> PAGE_CACHE_SHIFT;
+	rqstp->rq_enc_pages_num = last - first + 1 + 1;
+	rqstp->rq_enc_pages
+		= kmalloc(rqstp->rq_enc_pages_num * sizeof(struct page *),
+				GFP_NOFS);
+	if (!rqstp->rq_enc_pages)
+		goto out;
+	for (i=0; i < rqstp->rq_enc_pages_num; i++) {
+		rqstp->rq_enc_pages[i] = alloc_page(GFP_NOFS);
+		if (rqstp->rq_enc_pages[i] == NULL)
+			goto out_free;
+	}
+	rqstp->rq_release_snd_buf = priv_release_snd_buf;
+	return 0;
+out_free:
+	for (i--; i >= 0; i--) {
+		__free_page(rqstp->rq_enc_pages[i]);
+	}
+out:
+	return -EAGAIN;
+}
+
+static inline int
+gss_wrap_req_priv(struct rpc_cred *cred, struct gss_cl_ctx *ctx,
+		kxdrproc_t encode, struct rpc_rqst *rqstp, u32 *p, void *obj)
+{
+	struct xdr_buf	*snd_buf = &rqstp->rq_snd_buf;
+	u32		offset;
+	u32             maj_stat;
+	int		status;
+	u32		*opaque_len;
+	struct page	**inpages;
+	int		first;
+	int		pad;
+	struct kvec	*iov;
+	char		*tmp;
+
+	opaque_len = p++;
+	offset = (u8 *)p - (u8 *)snd_buf->head[0].iov_base;
+	*p++ = htonl(rqstp->rq_seqno);
+
+	status = encode(rqstp, p, obj);
+	if (status)
+		return status;
+
+	status = alloc_enc_pages(rqstp);
+	if (status)
+		return status;
+	first = snd_buf->page_base >> PAGE_CACHE_SHIFT;
+	inpages = snd_buf->pages + first;
+	snd_buf->pages = rqstp->rq_enc_pages;
+	snd_buf->page_base -= first << PAGE_CACHE_SHIFT;
+	/* Give the tail its own page, in case we need extra space in the
+	 * head when wrapping: */
+	if (snd_buf->page_len || snd_buf->tail[0].iov_len) {
+		tmp = page_address(rqstp->rq_enc_pages[rqstp->rq_enc_pages_num - 1]);
+		memcpy(tmp, snd_buf->tail[0].iov_base, snd_buf->tail[0].iov_len);
+		snd_buf->tail[0].iov_base = tmp;
+	}
+	maj_stat = gss_wrap(ctx->gc_gss_ctx, GSS_C_QOP_DEFAULT, offset,
+				snd_buf, inpages);
+	/* RPC_SLACK_SPACE should prevent this ever happening: */
+	BUG_ON(snd_buf->len > snd_buf->buflen);
+        status = -EIO;
+	/* We're assuming that when GSS_S_CONTEXT_EXPIRED, the encryption was
+	 * done anyway, so it's safe to put the request on the wire: */
+	if (maj_stat == GSS_S_CONTEXT_EXPIRED)
+		cred->cr_flags &= ~RPCAUTH_CRED_UPTODATE;
+	else if (maj_stat)
+		return status;
+
+	*opaque_len = htonl(snd_buf->len - offset);
+	/* guess whether we're in the head or the tail: */
+	if (snd_buf->page_len || snd_buf->tail[0].iov_len)
+		iov = snd_buf->tail;
+	else
+		iov = snd_buf->head;
+	p = iov->iov_base + iov->iov_len;
+	pad = 3 - ((snd_buf->len - offset - 1) & 3);
+	memset(p, 0, pad);
+	iov->iov_len += pad;
+	snd_buf->len += pad;
+
+	return 0;
+}
+
 static int
 gss_wrap_req(struct rpc_task *task,
 	     kxdrproc_t encode, void *rqstp, u32 *p, void *obj)
@@ -1002,6 +1111,8 @@ gss_wrap_req(struct rpc_task *task,
 								rqstp, p, obj);
 			break;
        		case RPC_GSS_SVC_PRIVACY:
+			status = gss_wrap_req_priv(cred, ctx, encode,
+					rqstp, p, obj);
 			break;
 	}
 out:
@@ -1048,6 +1159,36 @@ gss_unwrap_resp_integ(struct rpc_cred *cred, struct gss_cl_ctx *ctx,
 	return 0;
 }
 
+static inline int
+gss_unwrap_resp_priv(struct rpc_cred *cred, struct gss_cl_ctx *ctx,
+		struct rpc_rqst *rqstp, u32 **p)
+{
+	struct xdr_buf  *rcv_buf = &rqstp->rq_rcv_buf;
+	u32 offset;
+	u32 opaque_len;
+	u32 maj_stat;
+	int status = -EIO;
+
+	opaque_len = ntohl(*(*p)++);
+	offset = (u8 *)(*p) - (u8 *)rcv_buf->head[0].iov_base;
+	if (offset + opaque_len > rcv_buf->len)
+		return status;
+	/* remove padding: */
+	rcv_buf->len = offset + opaque_len;
+
+	maj_stat = gss_unwrap(ctx->gc_gss_ctx, NULL,
+			offset, rcv_buf);
+	if (maj_stat == GSS_S_CONTEXT_EXPIRED)
+		cred->cr_flags &= ~RPCAUTH_CRED_UPTODATE;
+	if (maj_stat != GSS_S_COMPLETE)
+		return status;
+	if (ntohl(*(*p)++) != rqstp->rq_seqno)
+		return status;
+
+	return 0;
+}
+
+
 static int
 gss_unwrap_resp(struct rpc_task *task,
 		kxdrproc_t decode, void *rqstp, u32 *p, void *obj)
@@ -1057,6 +1198,8 @@ gss_unwrap_resp(struct rpc_task *task,
 			gc_base);
 	struct gss_cl_ctx *ctx = gss_cred_get_ctx(cred);
 	u32		*savedp = p;
+	struct kvec	*head = ((struct rpc_rqst *)rqstp)->rq_rcv_buf.head;
+	int		savedlen = head->iov_len;
 	int             status = -EIO;
 
 	if (ctx->gc_proc != RPC_GSS_PROC_DATA)
@@ -1070,10 +1213,14 @@ gss_unwrap_resp(struct rpc_task *task,
 				goto out;
 			break;
        		case RPC_GSS_SVC_PRIVACY:
+			status = gss_unwrap_resp_priv(cred, ctx, rqstp, &p);
+			if (status)
+				goto out;
 			break;
 	}
 	/* take into account extra slack for integrity and privacy cases: */
-	task->tk_auth->au_rslack = task->tk_auth->au_verfsize + (p - savedp);
+	task->tk_auth->au_rslack = task->tk_auth->au_verfsize + (p - savedp)
+						+ (savedlen - head->iov_len);
 out_decode:
 	status = decode(rqstp, p, obj);
 out: