SUNRPC: Fix svcauth_gss_proxy_init()

commit 5866efa8cbfbadf3905072798e96652faf02dbe8 upstream.

gss_read_proxy_verf() assumes things about the XDR buffer containing
the RPC Call that are not true for buffers generated by
svc_rdma_recv().

RDMA's buffers look more like what the upper layer generates for
sending: head is a kmalloc'd buffer; it does not point to a page
whose contents are contiguous with the first page in the buffers'
page array. The result is that ACCEPT_SEC_CONTEXT via RPC/RDMA has
stopped working on Linux NFS servers that use gssproxy.

This does not affect clients that use only TCP to send their
ACCEPT_SEC_CONTEXT operation (that's all Linux clients). Other
clients, like Solaris NFS clients, send ACCEPT_SEC_CONTEXT on the
same transport as they send all other NFS operations. Such clients
can send ACCEPT_SEC_CONTEXT via RPC/RDMA.

I thought I had found every direct reference in the server RPC code
to the rqstp->rq_pages field.

Bug found at the 2019 Westford NFS bake-a-thon.

Fixes: 3316f0631139 ("svcrdma: Persistently allocate and DMA- ... ")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Bill Baker <bill.baker@oracle.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c
index 1a65f88..24c7a1e 100644 (file)
--- a/net/sunrpc/auth_gss/svcauth_gss.c
+++ b/net/sunrpc/auth_gss/svcauth_gss.c
@@ -1054,24 +1054,32 @@ gss_read_verf(struct rpc_gss_wire_cred *gc,
        return 0;
 }
 
-/* Ok this is really heavily depending on a set of semantics in
- * how rqstp is set up by svc_recv and pages laid down by the
- * server when reading a request. We are basically guaranteed that
- * the token lays all down linearly across a set of pages, starting
- * at iov_base in rq_arg.head[0] which happens to be the first of a
- * set of pages stored in rq_pages[].
- * rq_arg.head[0].iov_base will provide us the page_base to pass
- * to the upcall.
- */
-static inline int
-gss_read_proxy_verf(struct svc_rqst *rqstp,
-                   struct rpc_gss_wire_cred *gc, __be32 *authp,
-                   struct xdr_netobj *in_handle,
-                   struct gssp_in_token *in_token)
+static void gss_free_in_token_pages(struct gssp_in_token *in_token)
 {
-       struct kvec *argv = &rqstp->rq_arg.head[0];
        u32 inlen;
-       int res;
+       int i;
+
+       i = 0;
+       inlen = in_token->page_len;
+       while (inlen) {
+               if (in_token->pages[i])
+                       put_page(in_token->pages[i]);
+               inlen -= inlen > PAGE_SIZE ? PAGE_SIZE : inlen;
+       }
+
+       kfree(in_token->pages);
+       in_token->pages = NULL;
+}
+
+static int gss_read_proxy_verf(struct svc_rqst *rqstp,
+                              struct rpc_gss_wire_cred *gc, __be32 *authp,
+                              struct xdr_netobj *in_handle,
+                              struct gssp_in_token *in_token)
+{
+       struct kvec *argv = &rqstp->rq_arg.head[0];
+       unsigned int page_base, length;
+       int pages, i, res;
+       size_t inlen;
 
        res = gss_read_common_verf(gc, argv, authp, in_handle);
        if (res)
@@ -1081,10 +1089,36 @@ gss_read_proxy_verf(struct svc_rqst *rqstp,
        if (inlen > (argv->iov_len + rqstp->rq_arg.page_len))
                return SVC_DENIED;
 
-       in_token->pages = rqstp->rq_pages;
-       in_token->page_base = (ulong)argv->iov_base & ~PAGE_MASK;
+       pages = DIV_ROUND_UP(inlen, PAGE_SIZE);
+       in_token->pages = kcalloc(pages, sizeof(struct page *), GFP_KERNEL);
+       if (!in_token->pages)
+               return SVC_DENIED;
+       in_token->page_base = 0;
        in_token->page_len = inlen;
+       for (i = 0; i < pages; i++) {
+               in_token->pages[i] = alloc_page(GFP_KERNEL);
+               if (!in_token->pages[i]) {
+                       gss_free_in_token_pages(in_token);
+                       return SVC_DENIED;
+               }
+       }
 
+       length = min_t(unsigned int, inlen, argv->iov_len);
+       memcpy(page_address(in_token->pages[0]), argv->iov_base, length);
+       inlen -= length;
+
+       i = 1;
+       page_base = rqstp->rq_arg.page_base;
+       while (inlen) {
+               length = min_t(unsigned int, inlen, PAGE_SIZE);
+               memcpy(page_address(in_token->pages[i]),
+                      page_address(rqstp->rq_arg.pages[i]) + page_base,
+                      length);
+
+               inlen -= length;
+               page_base = 0;
+               i++;
+       }
        return 0;
 }
 
@@ -1259,8 +1293,11 @@ static int svcauth_gss_proxy_init(struct svc_rqst *rqstp,
                break;
        case GSS_S_COMPLETE:
                status = gss_proxy_save_rsc(sn->rsc_cache, &ud, &handle);
-               if (status)
+               if (status) {
+                       pr_info("%s: gss_proxy_save_rsc failed (%d)\n",
+                               __func__, status);
                        goto out;
+               }
                cli_handle.data = (u8 *)&handle;
                cli_handle.len = sizeof(handle);
                break;
@@ -1271,15 +1308,20 @@ static int svcauth_gss_proxy_init(struct svc_rqst *rqstp,
 
        /* Got an answer to the upcall; use it: */
        if (gss_write_init_verf(sn->rsc_cache, rqstp,
-                               &cli_handle, &ud.major_status))
+                               &cli_handle, &ud.major_status)) {
+               pr_info("%s: gss_write_init_verf failed\n", __func__);
                goto out;
+       }
        if (gss_write_resv(resv, PAGE_SIZE,
                           &cli_handle, &ud.out_token,
-                          ud.major_status, ud.minor_status))
+                          ud.major_status, ud.minor_status)) {
+               pr_info("%s: gss_write_resv failed\n", __func__);
                goto out;
+       }
 
        ret = SVC_COMPLETE;
 out:
+       gss_free_in_token_pages(&ud.in_token);
        gssp_free_upcall_data(&ud);
        return ret;
 }