[PATCH 5.4 017/102] SUNRPC: Fix svcauth_gss_proxy_init()

Greg Kroah-Hartman
2020-01-24T09:35:01Z

From: Chuck Lever <chuck.lever@oracle.com>

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>

---
net/sunrpc/auth_gss/svcauth_gss.c | 84 ++++++++++++++++++++++++++++----------
1 file changed, 63 insertions(+), 21 deletions(-)

--- a/net/sunrpc/auth_gss/svcauth_gss.c
+++ b/net/sunrpc/auth_gss/svcauth_gss.c
@@ -1075,24 +1075,32 @@ gss_read_verf(struct rpc_gss_wire_cred *
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)
@@ -1102,10 +1110,36 @@ gss_read_proxy_verf(struct svc_rqst *rqs
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;
}

@@ -1280,8 +1314,11 @@ static int svcauth_gss_proxy_init(struct
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;
@@ -1292,15 +1329,20 @@ static int svcauth_gss_proxy_init(struct

/* 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;
}