[PATCH] knfsd: svcrpc: gss: server-side implementation of rpcsec_gss privacy

Server-side implementation of rpcsec_gss privacy, which enables encryption of
the payload of every rpc request and response.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 148 insertions, 7 deletions

diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c
index ce8dc0db214e..94217ec9e2dd 100644
--- a/net/sunrpc/auth_gss/svcauth_gss.c
+++ b/net/sunrpc/auth_gss/svcauth_gss.c
@@ -832,6 +832,74 @@ out:
         return stat;
 }
 
+static inline int
+total_buf_len(struct xdr_buf *buf)
+{
+        return buf->head[0].iov_len + buf->page_len + buf->tail[0].iov_len;
+}
+
+static void
+fix_priv_head(struct xdr_buf *buf, int pad)
+{
+        if (buf->page_len == 0) {
+                /* We need to adjust head and buf->len in tandem in this
+                 * case to make svc_defer() work--it finds the original
+                 * buffer start using buf->len - buf->head[0].iov_len. */
+                buf->head[0].iov_len -= pad;
+        }
+}
+
+static int
+unwrap_priv_data(struct svc_rqst *rqstp, struct xdr_buf *buf, u32 seq, struct gss_ctx *ctx)
+{
+        u32 priv_len, maj_stat;
+        int pad, saved_len, remaining_len, offset;
+
+        rqstp->rq_sendfile_ok = 0;
+
+        priv_len = ntohl(svc_getu32(&buf->head[0]));
+        if (rqstp->rq_deferred) {
+                /* Already decrypted last time through! The sequence number
+                 * check at out_seq is unnecessary but harmless: */
+                goto out_seq;
+        }
+        /* buf->len is the number of bytes from the original start of the
+         * request to the end, where head[0].iov_len is just the bytes
+         * not yet read from the head, so these two values are different: */
+        remaining_len = total_buf_len(buf);
+        if (priv_len > remaining_len)
+                return -EINVAL;
+        pad = remaining_len - priv_len;
+        buf->len -= pad;
+        fix_priv_head(buf, pad);
+
+        /* Maybe it would be better to give gss_unwrap a length parameter: */
+        saved_len = buf->len;
+        buf->len = priv_len;
+        maj_stat = gss_unwrap(ctx, 0, buf);
+        pad = priv_len - buf->len;
+        buf->len = saved_len;
+        buf->len -= pad;
+        /* The upper layers assume the buffer is aligned on 4-byte boundaries.
+         * In the krb5p case, at least, the data ends up offset, so we need to
+         * move it around. */
+        /* XXX: This is very inefficient.  It would be better to either do
+         * this while we encrypt, or maybe in the receive code, if we can peak
+         * ahead and work out the service and mechanism there. */
+        offset = buf->head[0].iov_len % 4;
+        if (offset) {
+                buf->buflen = RPCSVC_MAXPAYLOAD;
+                xdr_shift_buf(buf, offset);
+                fix_priv_head(buf, pad);
+        }
+        if (maj_stat != GSS_S_COMPLETE)
+                return -EINVAL;
+out_seq:
+        if (ntohl(svc_getu32(&buf->head[0])) != seq)
+                return -EINVAL;
+        return 0;
+}
+
 struct gss_svc_data {
         /* decoded gss client cred: */
         struct rpc_gss_wire_cred        clcred;
@@ -1047,7 +1115,14 @@ svcauth_gss_accept(struct svc_rqst *rqstp, u32 *authp)
                         svc_putu32(resv, 0);
                         break;
                 case RPC_GSS_SVC_PRIVACY:
-                        /* currently unsupported */
+                        if (unwrap_priv_data(rqstp, &rqstp->rq_arg,
+                                        gc->gc_seq, rsci->mechctx))
+                                goto auth_err;
+                        /* placeholders for length and seq. number: */
+                        svcdata->body_start = resv->iov_base + resv->iov_len;
+                        svc_putu32(resv, 0);
+                        svc_putu32(resv, 0);
+                        break;
                 default:
                         goto auth_err;
                 }
@@ -1089,9 +1164,8 @@ svcauth_gss_wrap_resp_integ(struct svc_rqst *rqstp)
         gsd->body_start = NULL;
         /* move accept_stat to right place: */
         memcpy(p, p + 2, 4);
-        /* don't wrap in failure case: */
-        /* Note: counting on not getting here if call was not even
-         * accepted! */
+        /* Don't wrap in failure case: */
+        /* Counting on not getting here if call was not even accepted! */
         if (*p != rpc_success) {
                 resbuf->head[0].iov_len -= 2 * 4;
                 goto out;
@@ -1138,6 +1212,65 @@ out_err:
         return stat;
 }
 
+static inline int
+svcauth_gss_wrap_resp_priv(struct svc_rqst *rqstp)
+{
+        struct gss_svc_data *gsd = (struct gss_svc_data *)rqstp->rq_auth_data;
+        struct rpc_gss_wire_cred *gc = &gsd->clcred;
+        struct xdr_buf *resbuf = &rqstp->rq_res;
+        struct page **inpages = NULL;
+        u32 *p;
+        int offset, *len;
+        int pad;
+
+        p = gsd->body_start;
+        gsd->body_start = NULL;
+        /* move accept_stat to right place: */
+        memcpy(p, p + 2, 4);
+        /* Don't wrap in failure case: */
+        /* Counting on not getting here if call was not even accepted! */
+        if (*p != rpc_success) {
+                resbuf->head[0].iov_len -= 2 * 4;
+                return 0;
+        }
+        p++;
+        len = p++;
+        offset = (u8 *)p - (u8 *)resbuf->head[0].iov_base;
+        *p++ = htonl(gc->gc_seq);
+        inpages = resbuf->pages;
+        /* XXX: Would be better to write some xdr helper functions for
+         * nfs{2,3,4}xdr.c that place the data right, instead of copying: */
+        if (resbuf->tail[0].iov_base && rqstp->rq_restailpage == 0) {
+                BUG_ON(resbuf->tail[0].iov_base >= resbuf->head[0].iov_base
+                                                        + PAGE_SIZE);
+                BUG_ON(resbuf->tail[0].iov_base < resbuf->head[0].iov_base);
+                if (resbuf->tail[0].iov_len + resbuf->head[0].iov_len
+                                + 2 * RPC_MAX_AUTH_SIZE > PAGE_SIZE)
+                        return -ENOMEM;
+                memmove(resbuf->tail[0].iov_base + RPC_MAX_AUTH_SIZE,
+                        resbuf->tail[0].iov_base,
+                        resbuf->tail[0].iov_len);
+                resbuf->tail[0].iov_base += RPC_MAX_AUTH_SIZE;
+        }
+        if (resbuf->tail[0].iov_base == NULL) {
+                if (resbuf->head[0].iov_len + 2*RPC_MAX_AUTH_SIZE > PAGE_SIZE)
+                        return -ENOMEM;
+                resbuf->tail[0].iov_base = resbuf->head[0].iov_base
+                        + resbuf->head[0].iov_len + RPC_MAX_AUTH_SIZE;
+                resbuf->tail[0].iov_len = 0;
+                rqstp->rq_restailpage = 0;
+        }
+        if (gss_wrap(gsd->rsci->mechctx, offset, resbuf, inpages))
+                return -ENOMEM;
+        *len = htonl(resbuf->len - offset);
+        pad = 3 - ((resbuf->len - offset - 1)&3);
+        p = (u32 *)(resbuf->tail[0].iov_base + resbuf->tail[0].iov_len);
+        memset(p, 0, pad);
+        resbuf->tail[0].iov_len += pad;
+        resbuf->len += pad;
+        return 0;
+}
+
 static int
 svcauth_gss_release(struct svc_rqst *rqstp)
 {
@@ -1152,15 +1285,22 @@ svcauth_gss_release(struct svc_rqst *rqstp)
         if (gsd->body_start == NULL)
                 goto out;
         /* normally not set till svc_send, but we need it here: */
-        resbuf->len = resbuf->head[0].iov_len
-                + resbuf->page_len + resbuf->tail[0].iov_len;
+        /* XXX: what for?  Do we mess it up the moment we call svc_putu32
+         * or whatever? */
+        resbuf->len = total_buf_len(resbuf);
         switch (gc->gc_svc) {
         case RPC_GSS_SVC_NONE:
                 break;
         case RPC_GSS_SVC_INTEGRITY:
-                svcauth_gss_wrap_resp_integ(rqstp);
+                stat = svcauth_gss_wrap_resp_integ(rqstp);
+                if (stat)
+                        goto out_err;
                 break;
         case RPC_GSS_SVC_PRIVACY:
+                stat = svcauth_gss_wrap_resp_priv(rqstp);
+                if (stat)
+                        goto out_err;
+                break;
         default:
                 goto out_err;
         }
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index fb168a30fd3f..01ba60a49572 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -280,6 +280,7 @@ svc_process(struct svc_serv *serv, struct svc_rqst *rqstp)
         rqstp->rq_res.page_base = 0;
         rqstp->rq_res.page_len = 0;
         rqstp->rq_res.buflen = PAGE_SIZE;
+        rqstp->rq_res.tail[0].iov_base = NULL;
         rqstp->rq_res.tail[0].iov_len = 0;
         /* Will be turned off only in gss privacy case: */
         rqstp->rq_sendfile_ok = 1;