[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>

diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c
index ce8dc0d..94217ec 100644 (file)
--- 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 fb168a3..01ba60a 100644 (file)
--- 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;