[ 47/49] rpc: fix huge kmallocs in gss-proxy

Greg Kroah-Hartman
2013-09-29T19:50:08Z

From: "J. Bruce Fields" <bfields@redhat.com>

commit 9dfd87da1aeb0fd364167ad199f40fe96a6a87be upstream.

The reply to a gssproxy can include up to NGROUPS_MAX gid's, which will
take up more than a page. We therefore need to allocate an array of
pages to hold the reply instead of trying to allocate a single huge
buffer.

Tested-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/gss_rpc_upcall.c | 30 ++++++++++++++++++++++++++++++
net/sunrpc/auth_gss/gss_rpc_xdr.c | 3 +++
net/sunrpc/auth_gss/gss_rpc_xdr.h | 5 ++++-
3 files changed, 37 insertions(+), 1 deletion(-)

--- a/net/sunrpc/auth_gss/gss_rpc_upcall.c
+++ b/net/sunrpc/auth_gss/gss_rpc_upcall.c
@@ -213,6 +213,30 @@ static int gssp_call(struct net *net, st
return status;
}

+static void gssp_free_receive_pages(struct gssx_arg_accept_sec_context *arg)
+{
+ int i;
+
+ for (i = 0; i < arg->npages && arg->pages[i]; i++)
+ __free_page(arg->pages[i]);
+}
+
+static int gssp_alloc_receive_pages(struct gssx_arg_accept_sec_context *arg)
+{
+ int i;
+
+ arg->npages = DIV_ROUND_UP(NGROUPS_MAX * 4, PAGE_SIZE);
+ arg->pages = kzalloc(arg->npages * sizeof(struct page *), GFP_KERNEL);
+
+ for (i=0; i < arg->npages; i++) {
+ arg->pages[i] = alloc_page(GFP_KERNEL);
+ if (arg->pages[i] == NULL) {
+ gssp_free_receive_pages(arg);
+ return -ENOMEM;
+ }
+ }
+ return 0;
+}

/*
* Public functions
@@ -261,10 +285,16 @@ int gssp_accept_sec_context_upcall(struc
arg.context_handle = &ctxh;
res.output_token->len = GSSX_max_output_token_sz;

+ ret = gssp_alloc_receive_pages(&arg);
+ if (ret)
+ return ret;
+
/* use nfs/ for targ_name ? */

ret = gssp_call(net, &msg);

+ gssp_free_receive_pages(&arg);
+
/* we need to fetch all data even in case of error so
* that we can free special strctures is they have been allocated */
data->major_status = res.status.major_status;
--- a/net/sunrpc/auth_gss/gss_rpc_xdr.c
+++ b/net/sunrpc/auth_gss/gss_rpc_xdr.c
@@ -780,6 +780,9 @@ void gssx_enc_accept_sec_context(struct
/* arg->options */
err = dummy_enc_opt_array(xdr, &arg->options);

+ xdr_inline_pages(&req->rq_rcv_buf,
+ PAGE_SIZE/2 /* pretty arbitrary */,
+ arg->pages, 0 /* page base */, arg->npages * PAGE_SIZE);
done:
if (err)
dprintk("RPC: gssx_enc_accept_sec_context: %d\n", err);
--- a/net/sunrpc/auth_gss/gss_rpc_xdr.h
+++ b/net/sunrpc/auth_gss/gss_rpc_xdr.h
@@ -147,6 +147,8 @@ struct gssx_arg_accept_sec_context {
struct gssx_cb *input_cb;
u32 ret_deleg_cred;
struct gssx_option_array options;
+ struct page **pages;
+ unsigned int npages;
};

struct gssx_res_accept_sec_context {
@@ -240,7 +242,8 @@ int gssx_dec_accept_sec_context(struct r
2 * GSSX_max_princ_sz + \
8 + 8 + 4 + 4 + 4)
#define GSSX_max_output_token_sz 1024
-#define GSSX_max_creds_sz (4 + 4 + 4 + NGROUPS_MAX * 4)
+/* grouplist not included; we allocate separate pages for that: */
+#define GSSX_max_creds_sz (4 + 4 + 4 /* + NGROUPS_MAX*4 */)
#define GSSX_RES_accept_sec_context_sz (GSSX_default_status_sz + \
GSSX_default_ctx_sz + \
GSSX_max_output_token_sz + \