SUNRPC: Use xdr_stream for encoding GSS reply verifiers

Done as part of hardening the server-side RPC header encoding path.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c
index 8244895ca4f2298b0ca862450b9d70cbfcfe6e4d..3d82fbd44229ef3f610055780e9111a4ea511f98 100644 (file)
--- a/net/sunrpc/auth_gss/svcauth_gss.c
+++ b/net/sunrpc/auth_gss/svcauth_gss.c
@@ -693,28 +693,6 @@ alreadyseen:
        goto out;
 }
 
-static inline u32 round_up_to_quad(u32 i)
-{
-       return (i + 3 ) & ~3;
-}
-
-static inline int
-svc_safe_putnetobj(struct kvec *resv, struct xdr_netobj *o)
-{
-       u8 *p;
-
-       if (resv->iov_len + 4 > PAGE_SIZE)
-               return -1;
-       svc_putnl(resv, o->len);
-       p = resv->iov_base + resv->iov_len;
-       resv->iov_len += round_up_to_quad(o->len);
-       if (resv->iov_len > PAGE_SIZE)
-               return -1;
-       memcpy(p, o->data, o->len);
-       memset(p + o->len, 0, round_up_to_quad(o->len) - o->len);
-       return 0;
-}
-
 /*
  * Decode and verify a Call's verifier field. For RPC_AUTH_GSS Calls,
  * the body of this field contains a variable length checksum.
@@ -772,42 +750,6 @@ svcauth_gss_verify_header(struct svc_rqst *rqstp, struct rsc *rsci,
        return SVC_OK;
 }
 
-static int
-gss_write_verf(struct svc_rqst *rqstp, struct gss_ctx *ctx_id, u32 seq)
-{
-       __be32                  *xdr_seq;
-       u32                     maj_stat;
-       struct xdr_buf          verf_data;
-       struct xdr_netobj       mic;
-       __be32                  *p;
-       struct kvec             iov;
-       int err = -1;
-
-       svc_putnl(rqstp->rq_res.head, RPC_AUTH_GSS);
-       xdr_seq = kmalloc(4, GFP_KERNEL);
-       if (!xdr_seq)
-               return -ENOMEM;
-       *xdr_seq = htonl(seq);
-
-       iov.iov_base = xdr_seq;
-       iov.iov_len = 4;
-       xdr_buf_from_iov(&iov, &verf_data);
-       p = rqstp->rq_res.head->iov_base + rqstp->rq_res.head->iov_len;
-       mic.data = (u8 *)(p + 1);
-       maj_stat = gss_get_mic(ctx_id, &verf_data, &mic);
-       if (maj_stat != GSS_S_COMPLETE)
-               goto out;
-       *p++ = htonl(mic.len);
-       memset((u8 *)p + mic.len, 0, round_up_to_quad(mic.len) - mic.len);
-       p += XDR_QUADLEN(mic.len);
-       if (!xdr_ressize_check(rqstp, p))
-               goto out;
-       err = 0;
-out:
-       kfree(xdr_seq);
-       return err;
-}
-
 /*
  * Construct and encode a Reply's verifier field. The verifier's body
  * field contains a variable-length checksum of the GSS sequence
@@ -1454,8 +1396,6 @@ svcauth_gss_proc_init(struct svc_rqst *rqstp, struct rpc_gss_wire_cred *gc)
        u32 flavor, len;
        void *body;
 
-       svcxdr_init_encode(rqstp);
-
        /* Call's verf field: */
        if (xdr_stream_decode_opaque_auth(xdr, &flavor, &body, &len) < 0)
                return SVC_GARBAGE;
@@ -1642,15 +1582,15 @@ svcauth_gss_decode_credbody(struct xdr_stream *xdr,
 static int
 svcauth_gss_accept(struct svc_rqst *rqstp)
 {
-       struct kvec     *resv = &rqstp->rq_res.head[0];
        struct gss_svc_data *svcdata = rqstp->rq_auth_data;
        __be32          *rpcstart;
        struct rpc_gss_wire_cred *gc;
        struct rsc      *rsci = NULL;
-       __be32          *reject_stat = resv->iov_base + resv->iov_len;
        int             ret;
        struct sunrpc_net *sn = net_generic(SVC_NET(rqstp), sunrpc_net_id);
 
+       svcxdr_init_encode(rqstp);
+
        rqstp->rq_auth_stat = rpc_autherr_badcred;
        if (!svcdata)
                svcdata = kmalloc(sizeof(*svcdata), GFP_KERNEL);
@@ -1700,28 +1640,25 @@ svcauth_gss_accept(struct svc_rqst *rqstp)
        /* now act upon the command: */
        switch (gc->gc_proc) {
        case RPC_GSS_PROC_DESTROY:
-               if (gss_write_verf(rqstp, rsci->mechctx, gc->gc_seq))
+               if (!svcauth_gss_encode_verf(rqstp, rsci->mechctx, gc->gc_seq))
                        goto auth_err;
                /* Delete the entry from the cache_list and call cache_put */
                sunrpc_cache_unhash(sn->rsc_cache, &rsci->h);
-               if (resv->iov_len + 4 > PAGE_SIZE)
-                       goto drop;
-               svc_putnl(resv, RPC_SUCCESS);
+               if (xdr_stream_encode_u32(&rqstp->rq_res_stream, RPC_SUCCESS) < 0)
+                       goto auth_err;
                goto complete;
        case RPC_GSS_PROC_DATA:
                rqstp->rq_auth_stat = rpcsec_gsserr_ctxproblem;
-               svcdata->verf_start = resv->iov_base + resv->iov_len;
-               if (gss_write_verf(rqstp, rsci->mechctx, gc->gc_seq))
+               svcdata->verf_start = xdr_reserve_space(&rqstp->rq_res_stream, 0);
+               if (!svcauth_gss_encode_verf(rqstp, rsci->mechctx, gc->gc_seq))
                        goto auth_err;
                rqstp->rq_cred = rsci->cred;
                get_group_info(rsci->cred.cr_group_info);
                rqstp->rq_auth_stat = rpc_autherr_badcred;
                switch (gc->gc_svc) {
                case RPC_GSS_SVC_NONE:
-                       svcxdr_init_encode(rqstp);
                        break;
                case RPC_GSS_SVC_INTEGRITY:
-                       svcxdr_init_encode(rqstp);
                        /* placeholders for body length and seq. number: */
                        xdr_reserve_space(&rqstp->rq_res_stream, XDR_UNIT * 2);
                        if (svcauth_gss_unwrap_integ(rqstp, gc->gc_seq,
@@ -1730,7 +1667,6 @@ svcauth_gss_accept(struct svc_rqst *rqstp)
                        svcxdr_set_auth_slack(rqstp, RPC_MAX_AUTH_SIZE);
                        break;
                case RPC_GSS_SVC_PRIVACY:
-                       svcxdr_init_encode(rqstp);
                        /* placeholders for body length and seq. number: */
                        xdr_reserve_space(&rqstp->rq_res_stream, XDR_UNIT * 2);
                        if (svcauth_gss_unwrap_priv(rqstp, gc->gc_seq,
@@ -1755,8 +1691,7 @@ garbage_args:
        ret = SVC_GARBAGE;
        goto out;
 auth_err:
-       /* Restore write pointer to its original value: */
-       xdr_ressize_check(rqstp, reject_stat);
+       xdr_truncate_encode(&rqstp->rq_res_stream, XDR_UNIT * 2);
        ret = SVC_DENIED;
        goto out;
 complete: